research on cell phone radiation

Cell Phones and Cancer Risk

Why has there been concern that cell phones may cause cancer.

There are two main reasons why people are concerned that cell (or mobile) phones might have the potential to cause certain types of cancer or other health problems: Cell phones emit radiation (in the form of radiofrequency radiation , or radio waves ), and cell phone use is widespread. Even a small increase in cancer risk from cell phones would be of concern given how many people use them.

Brain and central nervous system cancers have been of particular concern because hand-held phones are used close to the head and because ionizing radiation—a higher energy form of radiation than what cell phones emit—has been found to cause some brain cancers. Many different kinds of studies have been carried out to try to investigate whether cell phone use is dangerous to human health.

However, the evidence to date suggests that cell phone use does not cause brain or other kinds of cancer in humans.

Is the radiation from cell phones harmful?

Cell phones emit radiation in the radiofrequency region of the electromagnetic spectrum . Second-, third-, and fourth-generation cell phones (2G, 3G, 4G) emit radiofrequency in the frequency range of 0.7–2.7 GHz. Fifth-generation (5G) cell phones are anticipated to use the frequency spectrum up to 80 GHz. 

These frequencies all fall in the nonionizing range of the spectrum, which is low frequency and low energy. The energy is too low to damage DNA. By contrast, ionizing radiation , which includes x-rays , radon , and cosmic rays, is high frequency and high energy. Energy from ionizing radiation can damage DNA. DNA damage can cause changes to genes that may increase the risk of cancer.

The NCI fact sheet Electromagnetic Fields and Cancer lists sources of radiofrequency radiation . More information about ionizing radiation can be found on the Radiation page.

The human body does absorb energy from devices that emit radiofrequency radiation. The only consistently recognized biological effect of radiofrequency radiation absorption in humans that the general public might encounter is heating to the area of the body where a cell phone is held (e.g., the ear and head). However, that heating is not sufficient to measurably increase core body temperature. There are no other clearly established dangerous health effects on the human body from radiofrequency radiation.

Has the incidence of brain and central nervous system cancers changed during the time cell phone use increased?

No. Investigators have studied whether the incidence of brain or other central nervous system cancers (that is, the number of new cases of these cancers diagnosed each year) has changed during the time that cell phone use increased dramatically. These studies found:

• stable incidence rates for adult gliomas in the United States ( 1 ), Nordic countries ( 2 ) and Australia ( 3 ) during the past several decades
• stable incidence rates for pediatric brain tumors in the United States during 1993–2013 ( 4 )
• stable incidence rates for acoustic neuroma ( 5 ), which are nonmalignant tumors , and meningioma ( 6 ), which are usually nonmalignant, among US adults since 2009 

In addition, studies using cancer incidence data have tested different scenarios (simulations) determining whether the incidence trends are in line with various levels of risk as reported in studies of cell phone use and brain tumors between 1979 and 2008 ( 7 , 8 ). These simulations showed that many risk changes reported in case-control studies  were not consistent with incidence data, implying that biases  and errors in the study may have distorted the findings.

Because these studies examine cancer incidence trends over time in populations rather than comparing risk in people who do and don’t use cell phones, their ability to observe potential small differences in risk among heavy users or susceptible populations is limited. Observational/epidemiologic studies—including case–control and cohort studies  (described below)—are designed to measure individual exposure to cell phone radiation and ascertain specific health outcomes.

How is radiofrequency radiation exposure measured in studies of groups of people?

Epidemiologic  studies use information from several sources, including questionnaires and data from cell phone service providers, to estimate radiofrequency radiation exposure in groups of people. Direct measurements are not yet possible outside of a laboratory setting. Estimates from studies reported to date take into account the following:

• How regularly study participants use cell phones (the number of calls per week or month)
• The age and the year when study participants first used a cell phone and the age and the year of last use (allows calculation of the duration of use and time since the start of use)
• The average number of cell phone calls per day, week, or month (frequency)
• The average length of a typical cell phone call
• The total hours of lifetime use, calculated from the length of typical call times, the frequency of use, and the duration of use

What has research shown about the link between cell phone use and cancer risk?

Researchers have carried out several types of population studies to investigate the possibility of a relationship between cell phone use and the risk of tumors, both malignant (cancerous) and nonmalignant (not cancer). Epidemiologic  studies (also called observational studies ) are research studies in which investigators observe groups of individuals (populations) and collect information about them but do not try to change anything about the groups. 

Two main types of epidemiologic studies— cohort studies  and case-control studies —have been used to examine associations between cell phone use and cancer risk. In a case–control study, cell phone use is compared between people who have tumors and people who don’t. In a cohort study, a large group of people who do not have cancer at the beginning of the study is followed over time and tumor development in people who did and didn’t use cell phones is compared. Cohort studies are limited by the fact that they may only be able to look at cell phone subscribers, who are not necessarily the cell phone users.

The tumors that have been investigated in epidemiologic studies include malignant brain tumors, such as gliomas , as well as nonmalignant tumors, such as acoustic neuroma (tumors in the cells of the nerve responsible for hearing that are also known as vestibular schwannomas), meningiomas (usually nonmalignant tumors in the membranes that cover and protect the brain and spinal cord ), parotid gland tumors (tumors in the salivary glands ), skin cancer, and thyroid gland tumors.

Three large epidemiologic studies have examined the possible association between cell phone use and cancer: Interphone, a case–control study; the Danish Study, a cohort study; and the Million Women Study, another cohort study. These studies have been critically evaluated in reviews reported in 2015 ( 9 ) and in 2019 ( 10 ). The findings of these studies are mixed, but overall, they do not show an association between cell phone use and cancer ( 11 – 22 ).   

Interphone Case–Control Study

How the study was done: This is the largest case–control study of cell phone use and the risk of head and neck tumors. It was conducted by a consortium of researchers from 13 countries. The data came from questionnaires that were completed by study participants in Europe, Israel, Canada, Australia, New Zealand, and Japan.

What the study showed: Most published analyses from this study have shown no increases overall in brain or other central nervous system cancers (glioma and meningioma) related to higher amounts of cell phone use. One analysis showed a statistically significant , although small, increase in the risk of glioma among study participants who spent the most total time on cell phone calls. However, for a variety of reasons the researchers considered this finding inconclusive ( 11 – 13 ).

An analysis of data from all 13 countries reported a statistically significant association between intracranial distribution of tumors within the brain and self-reported location of the phone ( 14 ). However, the authors of this study noted that it is not possible to draw firm conclusions about cause and effect based on their findings.

An analysis of data from five Northern European countries showed an increased risk of acoustic neuroma in those who had used a cell phone for 10 or more years ( 15 ). 

In subsequent analyses of Interphone data, investigators investigated whether tumors were more likely to form in areas of the brain with the highest exposure. One analysis showed no relationship between tumor location and level of radiation ( 16 ). However, another found evidence that glioma and, to a lesser extent, meningioma were more likely to develop where exposure was highest ( 17 ).

Danish Cohort Study

How the study was done: This cohort study linked billing information from more than 358,000 cell phone subscribers with brain tumor incidence data from the Danish Cancer Registry.

What the study showed: No association was observed between cell phone use and the incidence of glioma, meningioma, or acoustic neuroma, even among people who had been cell phone subscribers for 13 or more years ( 18 – 20 ).

Million Women Cohort Study

How the study was done: This prospective cohort study conducted in the United Kingdom used data obtained from questionnaires that were completed by study participants.

What the study showed: Self-reported cell phone use was not associated with an increased risk of glioma, meningioma, or non-central nervous system tumors. Although the original published findings reported an association with an increased risk of acoustic neuroma ( 21 ), it was not observed with additional years of follow-up of the cohort ( 22) .

Other Epidemiologic Studies

In addition to these three large studies, other, smaller epidemiologic studies have looked for associations between cell phone use and individual cancers in both adults and children. These include:

• Two NCI-sponsored case–control studies, each conducted in multiple US academic medical centers or hospitals between 1994 and 1998 that used data from questionnaires ( 23 ) or computer-assisted personal interviews ( 24 ). Neither study showed a relationship between cell phone use and the risk of glioma, meningioma, or acoustic neuroma in adults.
• The CERENAT study, another case–control study conducted in multiple areas in France from 2004 to 2006 using data collected in face-to-face interviews using standardized questionnaires ( 25 ). This study found no association for either gliomas or meningiomas when comparing adults who were regular cell phone users with non-users. However, the heaviest users had significantly increased risks of both gliomas and meningiomas.
• A pooled analysis of two case–control studies conducted in Sweden that reported statistically significant trends of increasing brain cancer risk for the total amount of cell phone use and the years of use among people who began using cell phones before age 20 ( 26 ).
• Another case–control study in Sweden, part of the Interphone pooled studies, did not find an increased risk of brain cancer among long-term cell phone users between the ages of 20 and 69 ( 27 ).
• The CEFALO study, an international case–control study of children diagnosed with brain cancer between ages 7 and 19, found no relationship between their cell phone use and risk for brain cancer ( 28 ).
• The MOBI-Kids study, a large international case–control study of young people ages 10 to 24 years diagnosed with brain tumors, found no evidence of an association between wireless phone use and the risk of brain tumors ( 29 ). 
• A population-based case–control study conducted in Connecticut found no association between cell phone use and the risk of thyroid cancer ( 30 ).

What are the findings from studies of the human body?

Researchers have carried out several kinds of studies to investigate possible effects of cell phone use on the human body. In 2011, two small studies were published that examined brain glucose metabolism in people after they had used cell phones. The results were inconsistent. One study showed increased glucose metabolism in the region of the brain close to the antenna compared with tissues on the opposite side of the brain ( 31 ); the other study ( 32 ) found reduced glucose metabolism on the side of the brain where the phone was used.

The authors of these studies noted that the results were preliminary and that possible health outcomes from changes in glucose metabolism in humans were unknown. Such inconsistent findings are not uncommon in experimental studies of the physiological effects of radiofrequency electromagnetic radiation in people ( 11 ). Some factors that can contribute to inconsistencies across such studies include assumptions used to estimate doses, failure to consider temperature effects, and investigators not being blinded to exposure status.

Another study investigated blood flow in the brain of people exposed to radiofrequency radiation from cell phones and found no evidence of an effect on blood flow in the brain ( 33 ).

What are the findings from experiments in laboratory animals?

Early studies involving laboratory animals showed no evidence that radiofrequency radiation increased cancer risk or enhanced the cancer-causing effects of known chemical carcinogens ( 34 – 37 ).

Because of inconsistent findings from epidemiologic studies in humans and the lack of clear data from previous experimental studies in animals, in 1999 the Food and Drug Administration (FDA) nominated radiofrequency radiation exposure associated with cell phone exposures for study in animal models by the US National Toxicology Program (NTP). NTP is an interagency program that coordinates toxicology research and testing across the US Department of Health and Human Services and is headquartered at the National Institute of Environmental Health Sciences, part of NIH.

The NTP studied radiofrequency radiation (2G and 3G frequencies) in rats and mice ( 38 , 39 ). This large project was conducted in highly specialized labs. The rodents experienced whole-body exposures of 3, 6, or 9 watts per kilogram of body weight for 5 or 7 days per week for 18 hours per day in cycles of 10 minutes on, 10 minutes off. A research overview of the rodent studies , with links to the peer-review summary, is available on the NTP website. The primary outcomes observed were a small number of cancers of Schwann cells  in the heart and non-cancerous changes ( hyperplasia ) in the same tissues for male rats, but not female rats, nor in mice overall.

These experimental findings raise new questions because cancers in the heart are extremely rare in humans. Schwann cells of the heart in rodents are similar to the kind of cells in humans that give rise to acoustic neuromas (also known as vestibular schwannomas), which some studies have suggested are increased in people who reported the heaviest use of cell phones. The NTP plans to continue to study radiofrequency exposure in animal models to provide insights into the biological changes that might explain the outcomes observed in their study.

Another animal study, in which rats were exposed 7 days per week for 19 hours per day to radiofrequency radiation at 0.001, 0.03, and 0.1 watts per kilogram of body weight was reported by investigators at the Italian Ramazzini Institute ( 40 ). Among the rats with the highest exposure levels, the researchers noted an increase in heart schwannomas in male rats and nonmalignant Schwann cell growth in the heart in male and female rats. However, key details necessary for interpretation of the results were missing: exposure methods, other standard operating procedures, and nutritional/feeding aspects. The gaps in the report from the study raise questions that have not been resolved.

ICNIRP (an independent nonprofit organization that provides scientific advice and guidance on the health and environmental effects of nonionizing radiation) critically evaluated both studies. It concluded that both followed good laboratory practice, including using more animals than earlier research and exposing the animals to radiofrequency radiation throughout their lifetimes. However, it also identified what it considered major weaknesses in how the studies were conducted and statistically analyzed and concluded that these limitations prevent drawing conclusions about the ability of radiofrequency exposures to cause cancer ( 41 ).

Why are the findings from different studies of cell phone use and cancer risk inconsistent?

A few studies have shown some evidence of statistical association of cell phone use and brain tumor risks in humans, but most studies have found no association. Reasons for these discrepancies include the following:

• Recall bias , which can occur when data about prior habits and exposures are collected from study participants using questionnaires administered after diagnosis of a disease in some of the participants. Study participants who have brain tumors, for example, may remember their cell phone use differently from individuals without brain tumors.
• Inaccurate reporting , which can happen when people say that something has happened more often or less often than it actually did. For example, people may not remember how much they used cell phones in a given time period.
• Morbidity and mortality among study participants who have brain cancer. Gliomas are particularly difficult to study because of their high death rate and the short survival of people who develop these tumors. Patients who survive initial treatment are often impaired, which may affect their responses to questions.
• Participation bias , which can happen when people who are diagnosed with brain tumors are more likely than healthy people (known as controls) to enroll in a research study.
• Changing technology. Older studies evaluated radiofrequency radiation exposure from analog cell phones. Today, cell phones use digital technology, which operates at a different frequency and a lower power level than analog phones, and cellular technology continues to change ( 42 ). 
• Exposure assessment limitations. Different studies measure exposure differently, which makes it difficult to compare the results of different studies ( 43 ). Investigations of sources and levels of exposure, particularly in children, are ongoing ( 44 ).
• Insufficient follow-up of highly exposed populations. It may take a very long time to develop symptoms after exposure to radiofrequency radiation, and current studies may not yet have followed participants long enough.
• Inadequate statistical power and methods to detect very small risks or risks that affect small subgroups of people specifically 
• Chance as an explanation of apparent effects may not have been considered.

What are other possible health effects from cell phone use?

The most consistent health risk associated with cell phone use is distracted driving and vehicle accidents ( 45 , 46 ). Several other potential health effects have been reported with cell phone use. Neurologic effects are of particular concern in young persons. However, studies of memory, learning, and cognitive function have generally produced inconsistent results ( 47 – 50 ).

What have expert organizations said about the cancer risk from cell phone use?

In 2011, the International Agency for Research on Cancer (IARC) , a component of the World Health Organization, appointed an expert working group to review all available evidence on the use of cell phones. The working group classified cell phone use as “possibly carcinogenic to humans,” based on limited evidence from human studies, limited evidence from studies of radiofrequency radiation and cancer in rodents, and inconsistent evidence from mechanistic studies ( 11 ).

The working group indicated that, although the human studies were susceptible to bias, the findings could not be dismissed as reflecting bias alone, and that a causal interpretation could not be excluded. The working group noted that any interpretation of the evidence should also consider that the observed associations could reflect chance, bias, or confounding variables rather than an underlying causal effect. In addition, the working group stated that the investigation of brain cancer risk associated with cell phone use poses complex research challenges.

The American Cancer Society’s cell phones page states “It is not clear at this time that RF (radiofrequency) waves from cell phones cause dangerous health effects in people, but studies now being done should give a clearer picture of the possible health effects in the future.” 

The National Institute of Environmental Health Sciences (NIEHS) states that the weight of the current scientific evidence has not conclusively linked cell phone use with any adverse health problems, but more research is needed.

The US Food and Drug Administration (FDA) notes that studies reporting biological changes associated with radiofrequency radiation have failed to be replicated and that the majority of human epidemiologic studies have failed to show a relationship between exposure to radiofrequency radiation from cell phones and health problems. FDA, which originally nominated this exposure for review by the NTP in 1999, issued a statement on the draft NTP reports released in February 2018, saying “based on this current information, we believe the current safety limits for cell phones are acceptable for protecting the public health.” FDA and the Federal Communications Commission (FCC) share responsibility for regulating cell phone technologies.

The US Centers for Disease Control and Prevention (CDC) states that no scientific evidence definitively answers whether cell phone use causes cancer.

The Federal Communications Commission (FCC) concludes that currently no scientific evidence establishes a definite link between wireless device use and cancer or other illnesses.

In 2015, the European Commission Scientific Committee on Emerging and Newly Identified Health Risks concluded that, overall, the epidemiologic studies on cell phone radiofrequency electromagnetic radiation exposure do not show an increased risk of brain tumors or of other cancers of the head and neck region ( 9 ). The committee also stated that epidemiologic studies do not indicate increased risk for other malignant diseases, including childhood cancer ( 9 ).

What studies of cell phone health effects are under way?

A large prospective cohort study of cell phone use and its possible long-term health effects was launched in Europe in March 2010. This study, known as Cohort Study of Mobile Phone Use and Health (or COSMOS ), has enrolled approximately 290,000 cell phone users aged 18 years or older to date and will follow them for 20 to 30 years ( 51 , 52 ).

Participants in COSMOS completed a questionnaire about their health, lifestyle, and current and past cell phone use when they joined the study. This information will be supplemented with information from health records and cell phone records. Research updates are posted to the COSMOS website .

The challenge of this ambitious study is to continue following the participants for a range of health effects over many decades. Researchers will need to determine whether participants who leave the study are somehow different from those who remain throughout the follow-up period.

Although recall bias is minimized in studies such as COSMOS that link participants to their cell phone records, such studies face other problems. For example, it is impossible to know who is using the listed cell phone or whether that individual also places calls using other cell phones. To a lesser extent, it is not clear whether multiple users of a single phone, for example family members who may share a device, will be represented on a single phone company account. Additionally, for many long-term cohort studies, participation tends to decline over time.

Has radiofrequency radiation from cell phone use been associated with cancer risk in children?

There are theoretical considerations as to why the potential health effects of cell phone use should be investigated separately in children. Their nervous systems are still developing and, therefore, more vulnerable to factors that may cause cancer. Their heads are smaller than those of adults and consequently have a greater proportional exposure to radiation emitted by cell phones. And, children have the potential of accumulating more years of cell phone exposure than adults.

Thus far, the data from studies of children with cancer do not suggest that children are at increased risk of developing cancer from cell phone use. The first published analysis came from a large case–control study called CEFALO, which was conducted in Europe. The study included 352 children who were diagnosed with brain tumors between 2004 and 2008 at the ages of 7 to 19 years. They were matched by age, sex, and geographical region with 646 young people randomly selected from population registries. Researchers did not find an association between cell phone use and brain tumor risk by amount of use or by the location of the tumor ( 28 ).

The largest case–control study among children, a 14-country study known as MOBI-Kids , included 899 young people ages 10 to 24 years who were diagnosed with brain tumors between 2010 and 2015. They were matched by sex, age, and region with 1,910 young people who were undergoing surgery for appendicitis. Researchers found no evidence of an association between wireless phone use and brain tumors in young people ( 29 ).

Which US federal agencies have a role in evaluating the effects of or regulating cell phones?

The National Institutes of Health (NIH), including the National Cancer Institute (NCI), conducts research on cell phone use and the risks of cancer and other diseases.

FDA and FCC share regulatory responsibilities for cell phones. FDA is responsible for testing and evaluating electronic product radiation and providing information for the public about the radiofrequency energy emitted by cell phones. FCC sets limits on the emissions of radiofrequency energy by cell phones and similar wireless products.

Where can I find more information about radiofrequency radiation from my cell phone?

The dose of the energy that people absorb from any source of radiation is estimated using a measure called the specific absorption rate (SAR), which is expressed in watts per kilogram of body weight ( 53 ). The SAR decreases very quickly as the distance to the exposure source increases. For cell phone users who hold their phones next to their head during voice calls, the highest exposure is to the brain, acoustic nerve, salivary gland, and thyroid.

The FCC provides information about the SAR of cell phones produced and marketed within the previous 1 to 2 years. Consumers can access this information using the phone’s FCC ID number, which is usually located on the case of the phone, and the FCC’s ID search form . SARs for older phones can be found by checking the phone settings or by contacting the manufacturer.

What can cell phone users do to reduce their exposure to radiofrequency radiation?

FDA has suggested some steps that concerned cell phone users can take to reduce their exposure to radiofrequency radiation ( 54 ):

• Reserve the use of cell phones for shorter conversations or for times when a landline phone is not available.
• Use a device with hands-free technology, such as wired headsets, which place more distance between the phone and the head of the user.

Use of wired or wireless headsets reduces the amount of radiofrequency radiation exposure to the head because the phone is not placed against the head ( 55 ). Exposures decline dramatically when cell phones are used hands-free.

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• Review Article
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• Published: 16 March 2021

5G mobile networks and health—a state-of-the-science review of the research into low-level RF fields above 6 GHz

• Ken Karipidis   ORCID: orcid.org/0000-0001-7538-7447 1 ,
• Rohan Mate 1 ,
• David Urban 1 ,
• Rick Tinker 1 &
• Andrew Wood 2  

Journal of Exposure Science & Environmental Epidemiology volume  31 ,  pages 585–605 ( 2021 ) Cite this article

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The increased use of radiofrequency (RF) fields above 6 GHz, particularly for the 5 G mobile phone network, has given rise to public concern about any possible adverse effects to human health. Public exposure to RF fields from 5 G and other sources is below the human exposure limits specified by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). This state-of-the science review examined the research into the biological and health effects of RF fields above 6 GHz at exposure levels below the ICNIRP occupational limits. The review included 107 experimental studies that investigated various bioeffects including genotoxicity, cell proliferation, gene expression, cell signalling, membrane function and other effects. Reported bioeffects were generally not independently replicated and the majority of the studies employed low quality methods of exposure assessment and control. Effects due to heating from high RF energy deposition cannot be excluded from many of the results. The review also included 31 epidemiological studies that investigated exposure to radar, which uses RF fields above 6 GHz similar to 5 G. The epidemiological studies showed little evidence of health effects including cancer at different sites, effects on reproduction and other diseases. This review showed no confirmed evidence that low-level RF fields above 6 GHz such as those used by the 5 G network are hazardous to human health. Future experimental studies should improve the experimental design with particular attention to dosimetry and temperature control. Future epidemiological studies should continue to monitor long-term health effects in the population related to wireless telecommunications.

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Introduction

There are continually emerging technologies that use radiofrequency (RF) electromagnetic fields particularly in telecommunications. Most telecommunication sources currently operate at frequencies below 6 GHz, including radio and TV broadcasting and wireless sources such as local area networks and mobile telephony. With the increasing demand for higher data rates, better quality of service and lower latency to users, future wireless telecommunication sources are planned to operate at frequencies above 6 GHz and into the ‘millimetre wave’ range (30–300 GHz) [ 1 ]. Frequencies above 6 GHz have been in use for many years in various applications such as radar, microwave links, airport security screening and in medicine for therapeutic applications. However, the planned use of millimetre waves by future wireless telecommunications, particularly the 5th generation (5 G) of mobile networks, has given rise to public concern about any possible adverse effects to human health.

The interaction mechanisms of RF fields with the human body have been extensively described and tissue heating is the main effect for RF fields above 100 kHz (e.g. HPA; SCENHIR) [ 2 , 3 ]. RF fields become less penetrating into body tissue with increasing frequency and for frequencies above 6 GHz the depth of penetration is relatively short with surface heating being the predominant effect [ 4 ].

International exposure guidelines for RF fields have been developed on the basis of current scientific knowledge to ensure that RF exposure is not harmful to human health [ 5 , 6 ]. The guidelines developed by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) in particular form the basis for regulations in the majority of countries worldwide [ 7 ]. In the frequency range above 6 GHz and up to 300 GHz the ICNIRP guidelines prevent excessive heating at the surface of the skin and in the eye.

Although not as extensively studied as RF fields at lower frequencies, a number of studies have investigated the effects of RF fields at frequencies above 6 GHz. Previous reviews have reported studies investigating frequencies above 6 GHz that show effects although many of the reported effects occurred at levels greater than the ICNIRP guidelines [ 1 , 8 ]. Given the public concern over the planned roll-out of 5 G using millimetre waves, it is important to determine whether there are any related adverse health consequences at levels encountered in the environment. The aim of this paper is to present a state-of-the-science review of the bioeffects research into RF fields above 6 GHz at low levels of exposure (exposure below the occupational limits of the ICNIRP guidelines). A meta-analysis of in vitro and in vivo studies, providing quantitative effect estimates for each study, is presented separately in a companion paper [ 9 ].

The state-of-the-science review included a comprehensive search of all available literature and examined the extent, range and nature of evidence into the bioeffects of RF fields above 6 GHz, at levels below the ICNIRP occupational limits. The review consisted of biomedical studies on low-level RF electromagnetic fields from 6 GHz to 300 GHz published at any starting date up to December 2019. Studies were initially found by searching the databases PubMed, EMF-Portal, Google Scholar, Embase and Web of Science using the search terms “millimeter wave”, “millimetre wave”, “gigahertz”, “GHz” and “radar”. We further searched major reviews published by health authorities on RF and health [ 2 , 3 , 10 , 11 ]. Finally, we searched the reference list of all the studies included. Studies were only included if the full paper was available in English.

Although over 300 studies were considered, this review was limited to experimental studies (in vitro, in vivo, human) where the stated RF exposure level was at or below the occupational whole-body limits specified by the ICNIRP (2020) guidelines: power density (PD) reference level of 50 W/m 2 or specific absorption rate (SAR) basic restriction of 0.4 W/kg. Since the PD occupational limits for local exposure are more relevant to in vitro studies, and since these limits are higher, we have included those studies with PD up to 100–200 W/m 2 , depending on frequency. The review included studies below the ICNIRP general public limits that are lower than the occupational limits.

The review also included epidemiological studies (cohort, case-control, cross-sectional) investigating exposure to radar but excluded studies where the stated radar frequencies were below 6 GHz. Epidemiological studies on radar were included as they represent occupational exposure below the ICNIRP guidelines. Case reports or case series were excluded. Studies investigating therapeutical outcomes were also excluded unless they reported specific bio-effects.

The state-of-the-science review appraised the quality of the included studies, but unlike a systematic review it did not exclude any studies based on quality. The review also identified gaps in knowledge for future investigation and research. The reporting of results in this paper is narrative with tabular accompaniment showing study characteristics. In this paper, the acronym “MMWs” (or millimetre waves) is used to denote RF fields above 6 GHz.

The review included 107 experimental studies (91 in vitro, 15 in vivo, and 1 human) that investigated various bioeffects, including genotoxicity, cell proliferation, gene expression, cell signalling, membrane function and other effects. The exposure characteristics and biological system investigated in experimental studies for the various bioeffects are shown in Tables  1 – 6 . The results of the meta-analysis of the in vitro and in vivo studies are presented separately in Wood et al. [ 9 ].

Genotoxicity

Studies have examined the effects of exposing whole human or mouse blood samples or lymphocytes and leucocytes to low-level MMWs to determine possible genotoxicity. Some of the genotoxicity studies have looked at the possible effects of MMWs on chromosome aberrations [ 12 , 13 , 14 ]. At exposure levels below the ICNIRP limits, the results have been inconsistent, with either a statistically significant increase [ 14 ] or no significant increase [ 12 , 13 ] in chromosome aberrations.

MMWs do not penetrate past the skin therefore epithelial and skin cells have been a common model of examination for possible genotoxic effects. DNA damage in a number of epithelial and skin cell types and at varied exposure parameters both below and above the ICNIRP limits have been examined using comet assays [ 15 , 16 , 17 , 18 , 19 ]. Despite the varied exposure models and methods used, no statistically significant evidence of DNA damage was identified in these studies. Evidence of genotoxic damage was further assessed in skin cells by the occurrence of micro-nucleation. De Amicis et al. [ 18 ] and Franchini et al. [ 19 ] reported a statistically significant increase in micro-nucleation, however, Hintzsche et al. [ 15 ] and Koyama et al. [ 16 , 17 ] did not find an effect. Two of the studies also examined telomere length and found no statistically significant difference between exposed and unexposed cells [ 15 , 19 ]. Last, a Ukrainian research group examined different skin cell types in three studies and reported an increase in chromosome condensation in the nucleus [ 20 , 21 , 22 ]; these results have not been independently verified. Overall, there was no confirmed evidence of MMWs causing genotoxic damage in epithelial and skin cells.

Three studies from an Indian research group have examined indicators of DNA damage and reactive oxygen species (ROS) production in rats exposed in vivo to MMWs. The studies reported DNA strand breaks based on evidence from comet assays [ 23 , 24 ] and changes in enzymes that control the build-up of ROS [ 24 ]. Kumar et al. also reported an increase in ROS production [ 25 ]. All the studies from this research group had low animal numbers (six animals exposed) and their results have not been independently replicated. An in vitro study that investigated ROS production in yeast cultures reported an increase in free radicals exposed to high-level but not low-level MMWs [ 26 ].

Other studies have looked at the effect of low-level MMWs on DNA in a range of different ways. Two studies reported that MMWs induce colicin synthesis and prophage induction in bacterial cells, both of which are suggested as indicative of DNA damage [ 27 , 28 ]. Another study suggested that DNA exposed to MMWs undergoes polymerase chain reaction synthesis differently than unexposed DNA [ 29 ], although no statistical analysis was presented. Hintzsche et al. reported statistically significant occurrence of spindle disturbance in hybrid cells exposed to MMWs [ 30 ]. Zeni et al. found no evidence of DNA damage or alteration of cell cycle kinetics in blood cells exposed to MMWs [ 31 ]. Last, two studies from a Russian research group examined the protective effects of MMWs where mouse blood leukocytes were pre-exposed to low-level MMWs and then to X-rays [ 32 , 33 ]. The studies reported that there was statistically significant less DNA damage in the leucocytes that were pre-exposed to MMWs than those exposed to X-rays alone. Overall, these studies had no independent replication.

Cell proliferation

A number of studies have examined the effects of low-level MMWs on cell proliferation and they have used a variety of cellular models and methods of investigation. Studies have exposed bacterial cells to low-level MMWs alone or in conjunction with other agents. Two early studies reported changes in the growth rate of E. coli cultures exposed to low-level MMWs; however, both of these studies were preliminary in nature without appropriate dosimetry or statistical analysis [ 34 , 35 ]. Two studies exposed E. coli cultures and one study exposed yeast cell cultures to MMWs alone, and before and after UVC exposure [ 36 , 37 , 38 ]. All three studies reported that MMWs alone had no significant effect on bacterial cell proliferation or survival. Rojavin et al., however, did report that when E. coli bacteria were exposed to MMWs after UVC sterilisation treatment, there was an increase in their survival rate [ 36 ]. The authors suggested this could be due to the MMW activation of bacterial DNA repair mechanisms. Other studies by an Armenian research group reported a reduction in E. coli cell growth when exposed to MMWs [ 39 , 40 , 41 , 42 , 43 , 44 , 45 ]. These studies reported that when E.coli cultures were exposed to MMWs in the presence of antibiotics, there was a greater reduction in the bacterial growth rate and an increase in the time between bacterial cell division compared with antibiotics exposure alone. Two of these studies investigated if these effects could be due to a reduction in the activity of the E. coli ATPase when exposed to MMWs. The studies reported exposure to MMWs in combination with particular antibiotics changed the concentration of H + and K + ions in the E.coli cells, which the authors linked to changes in ATPase activity [ 43 , 44 ]. Overall, the results from studies on cell proliferation of bacterial cells have been inconsistent with different research groups reporting conflicting results.

Studies have also examined how exposure to low-level MMWs could affect cell proliferation in yeast. Two early studies by a German research group reported changes in yeast cell growth [ 46 , 47 ]. However, another two independent studies did not report any changes in the growth rate of exposed yeast [ 48 , 49 ]. Furia et al. [ 48 ] noted that the Grundler and Keilmann studies [ 46 , 47 ] had a number of methodical issues, which may have skewed their results, such as poor exposure control and analysis of results. Another study exposed yeast to MMWs before and after UVC exposure and reported that MMWs did not change the rates of cell survival [ 37 ].

Studies have also examined the possible effect of low-level MMWs on tumour cells with some studies reporting a possible anti-proliferative effect. Chidichimo et al. reported a reduction in the growth of a variety of tumour cells exposed to MMWs; however, the results of the study did not support this conclusion [ 50 ]. An Italian research group published a number of studies investigating proliferation effects on human melanoma cell lines with conflicting results. Two of the studies reported reduced growth rate [ 51 , 52 ] and a third study showed no change in proliferation or in the cell cycle [ 53 ]. Beneduci et al. also reported changes in the morphology of MMW exposed cells; however, the authors did not present quantitative data for these reported changes [ 51 , 52 ]. In another study by the same Italian group, Beneduci et al. reported that exposure to low-level MMWs had a greater than 40% reduction in the number of viable erythromyeloid leukaemia cells compared with controls; however, there was no significant change in the number of dead cells [ 54 ]. More recently, Yaekashiwa et al. reported no statistically significant effect in proliferation or cellular activity in glioblastoma cells exposed to low-level MMWs [ 55 ].

Other studies did not report statistically significant effects on proliferation in chicken embryo cell cultures, rat nerve cells or human skin fibroblasts exposed to low-level MMWs [ 55 , 56 , 57 ].

Gene expression

Some studies have investigated whether low-level MMWs can influence gene expression. Le Queument et al. examined a multitude of genes using microarray analyses and reported transient expression changes in five of them. However, the authors concluded that these results were extremely minor, especially when compared with studies using microarrays to study known pollutants [ 58 ]. Studies by a French research group have examined the effect of MMWs on stress sensitive genes, stress sensitive gene promotors and chaperone proteins in human glial cell lines. In two studies, glial cells were exposed to low-level MMWs and there was no observed modification in the expression of stress sensitive gene promotors when compared with sham exposed cells [ 59 , 60 , 61 ]. Further, glial cells were examined for the expression of the chaperone protein clusterin (CLU) and heat shock protein HSP70. These proteins are activated in times of cellular stress to maintain protein functions and help with the repair process [ 60 ]. There was no observed modification in gene expression of the chaperone proteins. Other studies have examined the endoplasmic reticulum of glial cells exposed to MMWs [ 62 , 63 ]. The endoplasmic reticulum is the site of synthesis and folding of secreted proteins and has been shown to be sensitive to environmental insults [ 62 ]. The authors reported that there was no elevation in mRNA expression levels of endoplasmic reticulum specific chaperone proteins. Studies of stress sensitive genes in glial cells have consistently shown no modification due to low-level MMW exposure [ 59 , 60 , 61 , 62 , 63 ].

Belyaev and co-authors have studied a possible resonance effect of low-level MMWs primarily on Escherichia Coli (E. coli) cells and cultures. The Belyaev research group reported that the resonance effect of MMWs can change the conformation state of chromosomal DNA complexes [ 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 ]; however, most of these experiments were not temperature controlled. This resonance effect was not supported by earlier experiments on a number of different cell types conducted by Gandhi et al. and Bush et al. [ 75 , 76 ].

The results of Belyaev and co-workers have primarily been based on evidence from the anomalous viscosity time dependence (AVTD) method [ 77 ]. The research group argued that changes in the AVTD curve can indicate changes to the DNA conformation state and DNA-protein bonds. Belyaev and co-workers have reported in a number of studies that differences in the AVTD curve were dependent on several parameter including MMW characteristics (frequency, exposure level, and polarisation), cellular concentration and cell growth rate [ 69 , 71 , 72 , 73 , 74 ]. In some of the Belyaev studies E. coli were pre-exposed to X-rays, which was reported to change the AVTD curve; however, if the cells were then exposed to MMWs there was no longer a change in the AVTD curve [ 64 , 65 , 66 , 67 ]. The authors suggested that exposure to MMWs increased the rate of recovery in bacterial cells previously exposed to ionising radiation. The Belyaev group also used rat thymocytes in another study and they concluded that the results closely paralleled those found in E. coli cells [ 67 ]. The studies on the DNA conformation state change relied heavily on the AVTD method that has only been used by the Balyaev group and has not been independently validated [ 78 ].

Cell signalling and electrical activity

Studies examining effects of low-level MMWs on cell signalling have mainly involved MMW exposure to nervous system tissue of various animals. An in vivo study on rats recorded extracellular background electrical spike activity from neurons in the supraoptic nucleus of the hypothalamus after MMW exposure [ 79 ]. The study reported that there were changes in inter-spike interval and spike activity in the cells of exposed animals when compared with controls. There was also a mixture of significant shifts in neuron population proportions and spike frequency. The effect on the regularity of neuron spike activity was greater at higher frequencies. An in vitro study on rat cortical tissue slices reported that neuron firing rates decreased in half of the samples exposed to low-level MMWs [ 80 ]. The width of the signals was also decreased but all effects were short lived. The observed changes were not consistent between the two studies, but this could be a consequence of different brain regions being studied.

In vitro experiments by a Japanese research group conducted on crayfish exposed the dissected optical components and brain to MMWs [ 81 , 82 ]. Munemori and Ikeda reported that there was no significant change in the inter-spike intervals or amplitude of spontaneous discharges [ 81 ]. However, there was a change in the distribution of inter-spike intervals where the initial standard deviation decreased and then restored in a short time to a rhythm comparable to the control. A follow-up study on the same tissues and a wide range of exposure levels (many above the ICNIRP limits) reported similar results with the distribution of spike intervals decreasing with increasing exposure level [ 82 ]. These results on action potentials in crayfish tissue have not been independently investigated.

Mixed results were reported in experiments conducted by a US research group on sciatic frog nerve preparations. These studies applied electrical stimulation to the nerve and examined the effect of MMWs on the compound action potentials (CAPs) conductivity through the neurological tissue fibre. Pakhomov et al. found a reduction in CAP latency accompanied by an amplitude increase for MMWs above the ICNIRP limits but not for low-level MMWs [ 83 ]. However, in two follow-up studies, Pakhomov et al. reported that the attenuation in amplitude of test CAPs caused by high-rate stimulus was significantly reduced to the same magnitude at various MMW exposure levels [ 84 , 85 ]. In all of these studies, the observed effect on the CAPs was temporal and reversible, but there were implications of a frequency specific resonance interaction with the nervous tissue. These results on action potentials in frog sciatic nerves have not been investigated by others.

Other common experimental systems involved low-level MMW exposure to isolated ganglia of leeches. Pikov and Siegel reported that there was a decrease in the firing rate in one of the tested neurons and, through the measurement of input resistance in an inserted electrode, there was a transient dose-dependent change in membrane permeability [ 86 ]. However, Romanenko et al. found that low-level MMWs did not cause suppression of neuron firing rate [ 87 ]. Further experiments by Romanenko et al. reported that MMWs at the ICNIRP public exposure limit and above reported similar action potential firing rate suppression [ 88 ]. Significant differences were reported between MMW effects and effects due to an equivalent rise in temperature caused by heating the bathing solution by conventional means.

Membrane effects

Studies examining membrane interactions with low-level MMWs have all been conducted at frequencies above 40 GHz in in vitro experiments. A number of studies investigated membrane phase transitions involving exposure to a range of phospholipid vesicles prepared to mimic biological cell membranes. One group of studies by an Italian research group reported effects on membrane hydration dynamics and phase transition [ 89 , 90 , 91 ]. Observations included transition delays from the gel to liquid phase or vice versa when compared with sham exposures maintained at the same temperature; the effect was reversed after exposure. These reported changes remain unconfirmed by independent groups.

A number of studies investigated membrane permeability. One study focussed on Ca 2+ activated K + channels on the membrane surface of cultured kidney cells of African Green Marmosets [ 92 ]. The study reported modifications to the Hill coefficient and apparent affinity of the Ca 2+ by the K + channels. Another study reported that the effectiveness of a chemical to supress membrane permeability in the gap junction was transiently reduced when the cells were exposed to MMWs [ 93 , 94 ]. Two studies by one research group reported increases in the movement of molecules into skin cells during MMW exposure and suggested this indicates increased cell membrane permeability [ 21 , 91 ]. Permeability changes based on membrane pressure differences were also investigated in relation to phospholipid organisation [ 95 ]. Although there was no evidence of effects on phospholipid organisation on exposed model membranes, the authors reported a measurable difference in membrane pressure at low exposure levels. Another study reported neuron shrinkage and dehydration of brain tissues [ 96 ]. The study reported this was due to influences of low-level MMWs on the cellular bathing medium and intracellular water. Further, the authors suggested this influence of MMWs may have led to formation of unknown messengers, which are able to modulate brain cell hydration. A study using an artificial axon system consisting of a network of cells containing aqueous phospholipid vesicles reported permeability changes with exposure to MMWs by measuring K + efflux [ 97 ]. In this case, the authors emphasised limitations in applying this model to processes within a living organism. The varied effects of low-level MMWs on membrane permeability lack replication.

Other studies have examined the shape or size of vesicles to determine possible effects on membrane permeability. Ramundo-Orlando et al., reported effects on the shape of giant unilamellar vesicles (GUVs), specifically elongation, attributed to permeability changes [ 98 ]. However, another study reported that only smaller diameter vesicles demonstrated a statistically significant change when exposed to MMWs [ 99 ]. A study by Cosentino et al. examined the effect of MMWs on the size distributions of both large unilamellar vesicles (LUVs) and GUVs in in vitro preparations [ 100 ]. It was reported that size distribution was only affected when the vesicles were under osmotic stress, resulting in a statistically significant reduction in their size. In this case, the effect was attributed to dehydration as a result of membrane permeability changes. There is, generally, lack of replication on physical changes to phospholipid vesicles due to low-level MMWs.

Studies on E. coli and E. hirae cultures have reported resonance effects on membrane proteins and phospholipid constituents or within the media suspension [ 39 , 40 , 41 , 42 ]. These studies observed cell proliferation effects such as changes to cell growth rate, viability and lag phase duration. These effects were reported to be more pronounced at specific MMW frequencies. The authors suggested this could be due to a resonance effect on the cell membrane or the suspension medium. Torgomyan et al. and Hovnanyan et al. reported similar changes to proliferation that they attributed to changes in membrane permeability from MMW exposure [ 43 , 45 ]. These experiments were all conducted by an Armenian research group and have not been replicated by others.

Other effects

A number of studies have reported on the experimental results of other effects. Reproductive effects were examined in three studies on mice, rats and human spermatozoa. An in vivo study on mice exposed to low-level MMWs reported that spermatogonial cells had significantly more metaphase translocation disturbances than controls and an increased number of cells with unpaired chromosomes [ 101 ]. Another in vivo study on rats reported increased morphological abnormalities to spermatozoa following exposure, however, there was no statistical analysis presented [ 102 ]. Conversely, an in vitro study on human spermatozoa reported that there was an increase in motility after a short time of exposure to MMWs with no changes in membrane integrity and no generation of apoptosis [ 103 ]. All three of these studies looked at different effects on spermatozoa making it difficult to make an overall conclusion. A further two studies exposed rats to MMWs and examined their sperm for indicators of ROS production. One study reported both increases and decreases in enzymes that control the build-up of ROS [ 104 ]. The other study reported a decrease in the activity of histone kinase and an increase in ROS [ 105 ]. Both studies had low animal numbers (six animals exposed) and these results have not been independently replicated.

Immune function was also examined in a limited number of studies focussing on the effects of low-level MMWs on antigens and antibody systems. Three studies by a Russian research group that exposed neutrophils to MMWs reported frequency dependant changes in ROS production [ 106 , 107 , 108 ]. Another study reported a statistically significant decrease in antigen binding to antibodies when exposed to MMWs [ 109 ]; the study also reported that exposure decreased the stability of previously formed antigen–antibody complexes.

The effect on fatty acid composition in mice exposed to MMWs has been examined by a Russian research group using a number of experimental methods [ 110 , 111 , 112 ]. One study that exposed mice afflicted with an inflammatory condition to low-level MMWs reported no change in the fatty acid concentrations in the blood plasma. However, there was a significant increase in the omega-3 and omega-6 polyunsaturated fatty acid content of the thymus [ 110 ]. Another study exposed tumour-bearing mice and reported that monounsaturated fatty acids decreased and polyunsaturated fatty acids increased in both the thymus and tumour tissue. These changes resulted in fatty acid composition of the thymus tissue more closely resembling that of the healthy control animals [ 111 ]. The authors also examined the effect of exposure to X-rays of healthy mice, which was reported to reduce the total weight of the thymus. However, when the thymus was exposed to MMWs before or after exposure to X-rays, the fatty acid content was restored and was no longer significantly different from controls [ 112 ]. Overall, the authors reported a potential protective effect of MMWs on the recovery of fatty acids, however, all the results came from the same research group with a lack of replication from others.

Physiological effects were examined by a study conducted on mice exposed to WWMs to assess the safety of police radar [ 113 ]. The authors reported no statistically significant changes in the physiological parameters tested, which included body mass and temperature, peripheral blood and the mass and cellular composition, and number of cells in several important organs. Another study exposing human volunteers to low-level MMWs specifically examined cardiovascular function of exposed and sham exposed groups by electrocardiogram (ECG) and atrioventricular conduction velocity derivation [ 114 ]. This study reported that there were no significant differences in the physiological indicators assessed in test subjects.

Other individual studies have looked at various other effects. An early study reported differences in the attenuation of MMWs at specific frequencies in healthy and tumour cells [ 115 ]. Another early study reported no effect in the morphology of BHK-21/C13 cell cultures when exposed to low-level MMWs; the study did report morphological changes at higher levels, which were related to heating [ 116 ]. One study examined whether low-level MMWs induced cancer promotion in leukaemia and Lewis tumour cell grafted mice. The study reported no statistically significant growth promotion in either of the grafted cancer cell types [ 117 ]. Another study looked at the activity of gamma-glutamyl transpeptidase enzyme in rats after treatment with hydrocortisone and exposure to MMWs [ 118 ]. The study reported no effects at exposures below the ICNIRP limit, however, at levels above authors reported a range of effects. Another study exposed saline liquid solutions to continuous low and high level MMWs and reported temperature oscillations within the liquid medium but lacked a statistical analysis [ 119 ]. Another study reported that low-level MMWs decrease the mobility of the protozoa S. ambiguum offspring [ 120 ]. None of the reported effects in all of these other studies have been investigated elsewhere.

Epidemiological studies

There are no epidemiological studies that have directly investigated 5 G and potential health effects. There are however epidemiological studies that have looked at occupational exposure to radar, which could potentially include the frequency range from 6 to 300 GHz. Epidemiological studies on radar were included as they represent occupational exposure below the ICNIRP guidelines. The review included 31 epidemiological studies (8 cohort, 13 case-control, 9 cross-sectional and 1 meta-analysis) that investigated exposure to radar and various health outcomes including cancer at different sites, effects on reproduction and other diseases. The risk estimates as well as limitations of the epidemiological studies are shown in Table  7 .

Three large cohort studies investigated mortality in military personnel with potential exposure to MMWs from radar. Studies reporting on over 40-year follow-up of US navy veterans of the Korean War found that radar exposure had little effect on all-cause or cancer mortality with the second study reporting risk estimates below unity [ 121 , 122 ]. Similarly, in a 40-year follow-up of Belgian military radar operators, there was no statistically significant increase in all-cause mortality [ 123 , 124 ]; the study did, however, find a small increase in cancer mortality. More recently in a 25-year follow-up of military personnel who served in the French Navy, there was no increase in all-cause or cancer mortality for personnel exposed to radar [ 125 ]. The main limitation in the cohort studies was the lack of individual levels of RF exposure with most studies based on job-title. Comparisons were made between occupations with presumed high exposure to RF fields and other occupations with presumed lower exposure. This type of non-differential misclassification in dichotomous exposure assessment is associated mostly with an effect measure biased towards a null effect if there is a true effect of RF fields. If there is no true effect of RF fields, non-differential exposure misclassification will not bias the effect estimate (which will be close to the null value, but may vary because of random error). The military personnel in these studies were compared with the general population and this ‘healthy worker effect’ presents possible bias since military personnel are on average in better health than the general population; the healthy worker effect tends to underestimate the risk. The cohort studies also lacked information on possible confounding factors including other occupational exposures such as chemicals and lifestyle factors such as smoking.

Several epidemiological studies have specifically investigated radar exposure and testicular cancer. In a case-control study where most of the subjects were selected from military hospitals in Washington DC, USA, Hayes et al. found no increased risk between exposure to radar and testicular cancer [ 126 ]; exposure to radar was self-reported and thus subject to misclassification. In this study, the misclassification was likely non-differential, biasing the result towards the null. Davis and Mostofi reported a cluster of testicular cancer within a small cohort of 340 police officers in Washington State (USA) where the cases routinely used handheld traffic radar guns [ 127 ]; however, exposure was not assessed for the full cohort, which may have overestimated the risk. In a population-based case-control study conducted in Sweden, Hardell et al. did not find a statistically significant association between radar work and testicular cancer; however, the result was based on only five radar workers questioning the validity of this result [ 128 ]. In a larger population-based case control study in Germany, Baumgardt-Elms et al. also reported no association between working near radar units (both self-reported and expert assessed) and testicular cancer [ 129 ]; a limitation of this study was the low participation of identified controls (57%), however, there was no difference compared with the characteristics of the cases so selection bias was unlikely. In the cohort study of US navy veterans previously mentioned exposure to radar was not associated with testicular cancer [ 122 ]; the limitations of this cohort study mentioned earlier may have underestimated the risk. Finally, in a hospital-based case-control study in France, radar workers were also not associated with risk of testicular cancer [ 130 ]; a limitation was the low participation of controls (37%) with a difference in education level between participating and non-participating controls, which may have underestimated this result.

A limited number of studies have investigated radar exposure and brain cancer. In a nested case-control study within a cohort of male US Air Force personnel, Grayson reported a small association between brain cancer and RF exposure, which included radar [ 131 ]; no potential confounders were included in the analysis, which may have overestimated the result. However, in a case-control study of personnel in the Brazilian Navy, Santana et al. reported no association between naval occupations likely to be exposed to radar and brain cancer [ 132 ]; the small number of cases and lack of diagnosis confirmation may have biased the results towards the null. All of the cohort studies on military personnel previously mentioned also examined brain cancer mortality and found no association with exposure to radar [ 122 , 124 , 125 ].

A limited number of studies have investigated radar exposure and ocular cancer. Holly et al. in a population-based case-control study in the US reported an association between self-reported exposure to radar or microwaves and uveal melanoma [ 133 ]; the study investigated many different exposures and the result is prone to multiple testing. In another case-control study, which used both hospital and population controls, Stang et al. did not find an association between self-reported exposure to radar and uveal melanoma [ 134 ]; a high non-response in the population controls (52%) and exposure misclassification may have underestimated this result. The cohort studies of the Belgian military and French navy also found no association between exposure to radar and ocular cancer [ 124 , 125 ].

A few other studies have examined the potential association between radar and other cancers. In a hospital-based case-control study in Italy, La Vecchia investigated 14 occupational agents and risk of bladder cancer and found no association with radar, although no risk estimate was reported [ 135 ]; non-differential self-reporting of exposure may have underestimated this finding if there is a true effect. Finkelstein found an increased risk for melanoma in a large cohort of Ontario police officers exposed to traffic radar and followed for 31 years [ 136 ]; there was significant loss to follow up which may have biased this result in either direction. Finkelstein found no statistically significant associations with other types of cancer and the study reported a statistically significant risk estimate just below unity for all cancers, which is reflective of the healthy worker effect [ 136 ]. In a large population-based case-control study in France, Fabbro-Peray et al. investigated a large number of occupational and environmental risk factors in relation to non-Hodgkin lymphoma and found no association with radar operators based on job-title; however, the result was based on a small number of radar operators [ 137 ]. The cohort studies on military personnel did not find statistically significant associations between exposure to radar and other cancers [ 122 , 124 , 125 ].

Variani et al. conducted a recent systematic review and meta-analysis investigating occupational exposure to radar and cancer risk [ 138 ]. The meta-analysis included three cohort studies [ 122 , 124 , 125 ] and three case-control studies [ 129 , 130 , 131 ] for a total sample size of 53,000 subjects. The meta-analysis reported a decrease in cancer risk for workers exposed to radar but noted the small number of studies included with significant heterogeneity between the studies.

Apart from cancer, a number of epidemiological studies have investigated radar exposure and reproductive outcomes. Two early studies on military personnel in the US [ 139 ] and Denmark [ 140 ] reported differences in semen parameters between personnel using radar and personnel on other duty assignments; these studies included only volunteers with potential fertility concerns and are prone to bias. A further volunteer study on US military personnel did not find a difference in semen parameters in a similar comparison [ 141 ]; in general these type of cross-sectional investigations on volunteers provide limited evidence on possible risk. In a case-control study of personnel in the French military, Velez de la Calle et al. reported no association between exposure to radar and male infertility [ 142 ]; non-differential self-reporting of exposure may have underestimated this finding if there is a true effect. In two separate cross-sectional studies of personnel in the Norwegian navy, Baste et al. and Møllerløkken et al. reported an association between exposure to radar and male infertility, but there has been no follow up cohort or case control studies to confirm these results [ 143 , 144 ].

Again considering reproduction, a number of studies investigated pregnancy and offspring outcomes. In a population-based case-control study conducted in the US and Canada, De Roos et al. found no statistically significant association between parental occupational exposure to radar and neuroblastoma in offspring; however, the result was based on a small number of cases and controls exposed to radar [ 145 ]. In another cross-sectional study of the Norwegian navy, Mageroy et al. reported a higher risk of congenital anomalies in the offspring of personnel who were exposed to radar; the study found positive associations with a large number of other chemical and physical exposures, but the study involved multiple comparisons so is prone to over-interpretation [ 146 ]. Finally, a number of pregnancy outcomes were investigated in a cohort study of Norwegian navy personnel enlisted between 1950 and 2004 [ 147 ]. The study reported an increase in perinatal mortality for parental service aboard fast patrol boats during a short period (3 months); exposure to radar was one of many possible exposures when serving on fast patrol boats and the result is prone to multiple testing. No associations were found between long-term exposure and any pregnancy outcomes.

There is limited research investigating exposure to radar and other diseases. In a large case-control study of US military veterans investigating a range of risk factors and amyotrophic lateral sclerosis, Beard et al. did not find a statistically significant association with radar [ 148 ]; the study reported a likely under-ascertainment of non-exposed cases, which may have biased the result away from the null. The cohort studies on military personnel did not find statistically significant associations between exposure to radar and other diseases [ 122 , 124 , 125 ].

A number of observational studies have investigated outcomes measured on volunteers in the laboratory. They are categorised as epidemiological studies because exposure to radar was not based on provocation. These studies investigated genotoxicity [ 149 ], oxidative stress [ 149 ], cognitive effects [ 150 ] and endocrine function [ 151 ]; the studies generally reported positive associations with radar. These volunteer studies did not sample from a defined population and are prone to bias [ 152 ].

The experimental studies investigating exposure to MMWs at levels below the ICNIRP occupational limits have looked at a variety of biological effects. Genotoxicity was mainly examined by using comet assays of exposed cells. This approach has consistently found no evidence of DNA damage in skin cells in well-designed studies. However, animal studies conducted by one research group reported DNA strand breaks and changes in enzymes that control the build-up of ROS, noting that these studies had low animal numbers (six animals exposed); these results have not been independently replicated. Studies have also investigated other indications of genotoxicity including chromosome aberrations, micro-nucleation and spindle disturbances. The methods used to investigate these indicators have generally been rigorous; however, the studies have reported contradictory results. Two studies by a Russian research group have also reported indicators of DNA damage in bacteria, however, these results have not been verified by other investigators.

The studies of the effect of MMWs on cell proliferation primarily focused on bacteria, yeast cells and tumour cells. Studies of bacteria were mainly from an Armenian research group that reported a reduction in the bacterial growth rate of exposed E. coli cells at different MMW frequencies; however, the studies suffered from inadequate dosimetry and temperature control and heating due to high RF energy deposition may have contributed to the results. Other authors have reported no effect of MMWs on E. coli cell growth rate. The results on cell proliferation of yeast exposed to MMWs were also contradictory. An Italian research group that has conducted the majority of the studies on tumour cells reported either a reduction or no change in the proliferation of exposed cells; however, these studies also suffered from inadequate dosimetry and temperature control.

The studies on gene expression mainly examined two different indicators, expression of stress sensitive genes and chaperone proteins and the occurrence of a resonance effect in cells to explain DNA conformation state changes. Most studies reported no effect of low-level MMWs on the expression of stress sensitive genes or chaperone proteins using a range of experimental methods to confirm these results; noting that these studies did not use blinding so experimental bias cannot be excluded from the results. A number of studies from a Russian research group reported a resonance effect of MMWs, which they propose can change the conformation state of chromosomal DNA complexes. Their results relied heavily on the AVTD method for testing changes in the DNA conformation state, however, the biological relevance of results obtained through the AVTD method has not been independently validated.

Studies on cell signalling and electrical activity reported a range of different outcomes including increases or decreases in signal amplitude and changes in signal rhythm, with no consistent effect noting the lack of blinding in most of the studies. Further, temperature contributions could not be eliminated from the studies and in some cases thermal interactions by conventional heating were studied and found to differ from the MMW effects. The results from some studies were based on small sample sizes, some being confined to a single specimen, or by observed effects only occurring in a small number of the samples tested. Overall, the reported electrical activity effects could not be dismissed as being within normal variability. This is indicated by studies reporting the restoration of normal function within a short time during ongoing exposure. In this case there is no implication of an expected negative health outcome.

Studies on membrane effects examined changes in membrane properties and permeability. Some studies observed changes in transitions from liquid to gel phase or vice versa and the authors implied that MMWs influenced cell hydration, however the statistical methods used in these studies were not described so it is difficult to examine the validity of these results. Other studies observing membrane properties in artificial cell suspensions and dissected tissue reported changes in vesicle shape, reduced cell volume and morphological changes although most of these studies suffered from various methodological problems including poor temperature control and no blinding. Experiments on bacteria and yeast were conducted by the same research group reporting changes in membrane permeability, which was attributed to cell proliferation effects, however, the studies suffered from inadequate dosimetry and temperature control. Overall, although there were a variety of membrane bioeffects reported, these have not been independently replicated.

The limited number of studies on a number of other effects from exposure to MMWs below the ICNIRP limits generally reported little to no consistent effects. The single in vivo study on cancer promotion did not find an effect although the study did not include sham controls. Effects on reproduction were contradictory that may have been influenced by opposing objectives of examining adverse health effects or infertility treatment. Further, the only study on human sperm found no effects of low-level MMWs. The studies on reproduction suffered from inadequate dosimetry and temperature control, and since sperm is sensitive to temperature, the effect of heating due to high RF energy deposition may have contributed to the studies showing an effect. A number of studies from two research groups reported effects on ROS production in relation to reproduction and immune function; the in vivo studies had low animal numbers (six animals per exposure) and the in vitro studies generally had inadequate dosimetry and temperature control. Studies on fatty acid composition and physiological indicators did not generally show any effects; poor temperature control was also a problem in the majority of these studies. A number of other studies investigating various other biological effects reported mixed results.

Although a range of bioeffects have been reported in many of the experimental studies, the results were generally not independently reproduced. Approximately half of the studies were from just five laboratories and several studies represented a collaboration between one or more laboratories. The exposure characteristics varied considerably among the different studies with studies showing the highest effect size clustered around a PD of approximately 1 W/m 2 . The meta-analysis of the experimental studies in our companion paper [ 9 ] showed that there was no dose-response relationship between the exposure (either PD or SAR) and the effect size. In fact, studies with a higher exposure tended to show a lower effect size, which is counterfactual. Most of the studies showing a large effect size were conducted in the frequency range around 40–55 GHz, representing investigations into the use of MMWs for therapeutic purposes, rather than deleterious health consequences. Future experimental research would benefit from investigating bioeffects at the specific frequency range of the next stage of the 5 G network roll-out in the range 26–28 GHz. Mobile communications beyond the 5 G network plan to use frequencies higher than 30 GHz so research across the MMW band is relevant.

An investigation into the methods of the experimental studies showed that the majority of studies were lacking in a number of quality criteria including proper attention to dosimetry, incorporating positive controls, using blind evaluation or accurately measuring or controlling the temperature of the biological system being tested. Our meta-analysis showed that the bulk of the studies had a quality score lower than 2 out of a possible 5, with only one study achieving a maximum quality score of 5 [ 9 ]. The meta-analysis further showed that studies with a low quality score were more likely to show a greater effect. Future research should pay careful attention to the experimental design to reduce possible sources of artefact.

The experimental studies included in this review reported PDs below the ICNIRP exposure limits. Many of the authors suggested that the resulting biological effects may be related to non-thermal mechanisms. However, as is shown in our meta-analysis, data from these studies should be treated with caution because the estimated SAR values in many of the studies were much higher than the ICNIRP SAR limits [ 9 ]. SAR values much higher than the ICNIRP guidelines are certainly capable of producing significant temperature rise and are far beyond the levels expected for 5 G telecommunication devices [ 1 ]. Future research into the low-level effects of MMWs should pay particular attention to appropriate temperature control in order to avoid possible heating effects.

Although a systematic review of experimental studies was not conducted, this paper presents a critical appraisal of study design and quality of all available studies into the bioeffects of low level MMWs. The conclusions from the review of experimental studies are supported by a meta-analysis in our companion paper [ 9 ]. Given the low-quality methods of the majority of the experimental studies we infer that a systematic review of different bioeffects is not possible at present. Our review includes recommendations for future experimental research. A search of the available literature showed a further 44 non-English papers that were not included in our review. Although the non-English papers may have some important results it is noted that the majority are from research groups that have published English papers that are included in our review.

The epidemiological studies on MMW exposure from radar that has a similar frequency range to that of 5 G and exposure levels below the ICNIRP occupational limits in most situations, provided little evidence of an association with any adverse health effects. Only a small number of studies reported positive associations with various methodological issues such as risk of bias, confounding and multiple testing questioning the result. The three large cohort studies of military personnel exposed to radar in particular did not generally show an association with cancer or other diseases. A key concern across all the epidemiological studies was the quality of exposure assessment. Various challenges such as variability in complex occupational environments that also include other co-exposures, retrospective estimation of exposure and an appropriate exposure metric remain central in studies of this nature [ 153 ]. Exposure in most of the epidemiological studies was self-reported or based on job-title, which may not necessarily be an adequate proxy for exposure to RF fields above 6 GHz. Some studies improved on exposure assessment by using expert assessment and job-exposure matrices, however, the possibility of exposure misclassification is not eliminated. Another limitation in many of the studies was the poor assessment of possible confounding including other occupational exposures and lifestyle factors. It should also be noted that close proximity to certain very powerful radar units could have exceeded the ICNIRP occupational limits, therefore the reported effects especially related to reproductive outcomes could potentially be related to heating.

Given that wireless communications have only recently started to use RF frequencies above 6 GHz there are no epidemiological studies investigating 5 G directly as yet. Some previous epidemiological studies have reported a possible weak association between mobile phone use (from older networks using frequencies below 6 GHz) and brain cancer [ 11 ]. However, methodological limitations in these studies prevent conclusions of causality being drawn from the observations [ 152 ]. Recent investigations have not shown an increase in the incidence of brain cancer in the population that can be attributed to mobile phone use [ 154 , 155 ]. Future epidemiological research should continue to monitor long-term health effects in the population related to wireless telecommunications.

The review of experimental studies provided no confirmed evidence that low-level MMWs are associated with biological effects relevant to human health. Many of the studies reporting effects came from the same research groups and the results have not been independently reproduced. The majority of the studies employed low quality methods of exposure assessment and control so the possibility of experimental artefact cannot be excluded. Further, many of the effects reported may have been related to heating from high RF energy deposition so the assertion of a ‘low-level’ effect is questionable in many of the studies. Future studies into the low-level effects of MMWs should improve the experimental design with particular attention to dosimetry and temperature control. The results from epidemiological studies presented little evidence of an association between low-level MMWs and any adverse health effects. Future epidemiological research would benefit from specific investigation on the impact of 5 G and future telecommunication technologies.

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This work was supported by the Australian Government’s Electromagnetic Energy Program. This work was also partly supported by National Health and Medical Research Council grant no. 1042464. 

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Karipidis, K., Mate, R., Urban, D. et al. 5G mobile networks and health—a state-of-the-science review of the research into low-level RF fields above 6 GHz. J Expo Sci Environ Epidemiol 31 , 585–605 (2021). https://doi.org/10.1038/s41370-021-00297-6

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Do I Need to Worry About Smartphone Radiation?

Some studies have linked cellphone use with cancer, so we asked some experts to explain the risk.

Credit... Eric Helgas for The New York Times

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By Caroline Hopkins

• Nov. 14, 2023

Q: I’m constantly on my phone, and it’s usually near my body when I’m not. Should I worry about radiation exposure?

Spending all day glued to your smartphone probably isn’t doing you any favors. Excess phone use has been linked with a range of concerns, including sleep issues , elevated cortisol levels , joint pain and even relationship woes .

But if it’s radiation you’re worried about, experts say you don’t have to ditch your phone.

“There’s no risk of anything hazardous or dangerous with radiation from cellphones,” said Gayle Woloschak, an associate dean and professor of radiology at the Northwestern University Feinberg School of Medicine.

As with all cellphones (along with Wi-Fi networks, radio stations, remote controls and GPS), smartphones do emit radiation, said Emily Caffrey, an assistant professor of health physics at the University of Alabama at Birmingham. They use invisible energy waves to transmit voices, texts, photos and emails to nearby cell towers, which can shuttle them to virtually anywhere in the world.

But nearly three decades of scientific research has not linked such exposures to medical issues like cancer, health authorities including the Food and Drug Administration say. Here’s what we know.

Not all radiation is harmful

“Radiation” describes many types of energy, some of which do carry risks, said Dr. Howard Fine, director of the Brain Tumor Center at NewYork-Presbyterian Weill Cornell Medical Center in New York City.

Atomic bombs, or, to a far lesser degree, X-ray machines, emit energy called ionizing radiation that — in high enough or frequent enough doses — can damage DNA and cause cancer, Dr. Fine said.

This is why you usually wear a protective lead blanket during X-rays.

But smartphone energy falls into a category called non-ionizing radiation, Dr. Caffrey said, which isn’t powerful enough to cause this damage.

“A lot of people think ‘radiation is radiation,’ but it’s not all the same.” Dr. Woloschak said. “There’s no DNA damage seen from cellphone use.”

The more dangerous ionizing radiation can separate electrons from atoms, which make up our DNA. Over time, DNA damage can cause cancer.

Why is there still concern?

Most experts and health authorities like the F.D.A., Centers for Disease Control and Prevention and World Health Organization agree that there’s no evidence that smartphone radiation causes health problems. Still, several studies over the years have made headlines for suggesting their links to brain tumors. Many of these studies have since been debunked, Dr. Fine said, including those focused on fifth-generation mobile networks, or 5G .

In one study published in 2010 , for instance, researchers found a small association between one type of brain tumor and the highest levels of cellphone use. But the study’s own researchers noted that “biases and error” prevented them from proving cause and effect. Of the study’s various flaws, according to its authors, one was that it relied on people with brain cancer to correctly remember exactly how much they used their phones over many years.

All of the experts interviewed for this story said that the few studies that have suggested that smartphones pose radiation risks didn’t actually prove that cellphones caused those health issues.

Most people in the United States own cellphones, according to the Pew Research Center — and it would be nearly impossible to single out cellphones as a reason someone developed cancer, Dr. Fine said. Unrelated risk factors, such as exposure to air pollution, smoking, unhealthy habits or even just chance, could have been the culprits.

Yet studies with flaws like these have muddied perceptions about phone safety, the National Cancer Institute says.

Staying on the safe side

Cellphones today are nothing like the brick phones of the early 2000s. The phones we’ll use next decade will be different, too. This makes it challenging to study the long-term risks from any one phone. But Dr. Fine said radiation has actually decreased with newer technology, and Dr. Woloschak said new networks aren’t riskier than older ones, either.

“5G radiation is no higher than the 4G was,” she said. “It just allows for greater data transfer.”

Still, the Federal Communications Commission and its international counterparts set radiation limits for new phones . This explains why, in September, French authorities told Apple that it must lower the radiation levels emitted by the iPhone 12 to comply with its maximum limits. Apple rolled out a software update to fix the issue.

Dr. Caffrey said these limits are based on radiation levels that could theoretically raise our body temperatures a fraction of a degree. According to Dr. Woloschak, radiation would need to heat our bodies several full degrees to pose health risks like burns or a fever. “A cellphone’s never going to do that,” she said.

Caroline Hopkins is a health and science journalist based in Brooklyn.

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Trying to spend less time on your phone? The “Do Not Disturb” mode can help you set boundaries and signal that it may take you a while to respond .

To comply with recent European regulations, Apple will make a switch to USB-C charging for its iPhones. Here is how to navigate the change .

Photo apps have been using A.I. for years to give you control over the look of your images. Here’s how to take advantage of that .

The loss of your smartphone can be disruptive and stressful. Taking a few simple steps ahead of time can make things easier if disaster strikes .

Many default settings make us share superfluous amounts of data with tech companies. Here’s how to shut those off .

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March 29, 2018

New Studies Link Cell Phone Radiation with Cancer

Researchers call for greater caution, but skeptics say the evidence from rat studies is not convincing

By Charles Schmidt

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Does cell phone radiation cause cancer? New studies show a correlation in lab rats, but the evidence may not resolve ongoing debates over causality or whether any effects arise in people.

The ionizing radiation given off by sources such as x-ray machines and the sun boosts cancer risk by shredding molecules in the body. But the non-ionizing radio-frequency (RF) radiation that cell phones and other wireless devices emit has just one known biological effect: an ability to heat tissue by exciting its molecules.

Still, evidence advanced by the studies shows prolonged exposure to even very low levels of RF radiation, perhaps by mechanisms other than heating that remain unknown, makes rats uniquely prone to a rare tumor called a schwannoma, which affects a type of neuron (or nerve cell) called a Schwann cell.

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The studies are notable for their sizes. Researchers at the National Toxicology Program, a federal interagency group under the National Institutes of Health, tested 3,000 rats and mice of both sexes for two years—the largest investigation of RF radiation and cancer in rodents ever undertaken in the U.S. European investigators at the Ramazzini Institute in Italy were similarly ambitious; in their recent study they investigated RF effects in nearly 2,500 rats from the fetal stage until death.

Also noteworthy is that the studies evaluated radiation exposures in different ways. The NTP looked at “near-field” exposures, which approximate how people are dosed while using cell phones. Ramazzini researchers looked at “far-field” exposures, which approximate the wireless RF radiation that bombards us from sources all around us, including wireless devices such as tablet and laptop computers. Yet they generated comparable results: Male rats in both studies (but not mice or female animals) developed schwannomas of the heart at statistically higher rates than control animals that were not exposed.

Taken together, the findings “confirm that RF radiation exposure has biological effects” in rats, some of them “relevant to carcinogenesis,” says Jon Samet, a professor of preventive medicine and dean of the Colorado School of Public Health, who did not participate in either study. Samet, however, cautioned the jury is still out as to whether wireless technology is similarly risky to people. Indeed, heart schwannomas are exceedingly rare in humans; only a handful of cases have ever been documented in the medical literature.

When turned on, cell phones and other wireless devices emit RF radiation continually, even if they are not being actively used, because they are always communicating with cell towers. The dose intensity tails off with increasing distance from the body, and reaches a maximum when the devices are used next to the head during phone calls or in front of the body during texting or tweeting.

Launched at the U.S. Food and Drug Administration’s request 10 years ago, the NTP study dosed rats and mice of both sexes with RF radiation at either 1.5, 3 or 6 watts of radiation per kilogram of body weight, or W/kg. The lowest dose is about the same as the Federal Communications Commission’s limit for public exposure from cell phones, which is 1.6 watts W/kg. The animals were exposed nine hours a day for two years (about the average life span for a rat), and the exposures were cranked up steadily as the animals grew, so the absorbed doses per unit body weight remained constant over time.

Initially leaked in 2016 , results from that $25-million study provided the most compelling evidence yet that RF energy may be linked to cancer in lab rodents. The strongest finding connected RF with heart schwannomas in male rats, but the researchers also reported elevated rates of lymphoma as well as cancers affecting the prostate, skin, lung, liver and brain in the exposed animals. Rates for those cancers increased as the doses got higher but the evidence linking them with cell phone radiation specifically was weak by comparison, and the researchers could not rule out that they might have increased for reasons other than RF exposure. Paradoxically, the radiation-treated animals also lived longer than the nonexposed controls. The study results were reviewed by a panel of outside experts during a three-day meeting that ended on March 28. They concluded there was "clear evidence" linking RF radiation with heart schwannomas and "some evidence" linking it to gliomas of the brain. It is now up to the NTP to either accept or reject the reviewer's conclusions. A final report is expected within several months.

Limited to rats only, the Ramazzini study tested three doses expressed as the amount of radiation striking the animal’s bodies: either 5, 25 or 50 volts per meter. The exposure measures therefore differed from the absorbed doses calculated during the NTP study. But the Ramazzini scientists also converted their measures to W/kg, to show how the doses compared with RF limits for cell phones and cell towers set by the FCC and the International Commission on Non-Ionizing Radiation Protection; they ranged down to a 1,000 times lower. The exposures began when the rats were fetuses and continued for 19 hours a day until the animals died from natural causes.

As in the NTP study, Ramazzini investigators detected statistically elevated rates of heart schwannomas in male rats at the highest dose. They also had weaker findings linking RF exposure to cancer of glial cells in the brain, which were limited to females. Ronald Melnick, a retired NTP toxicologist who designed the NTP study, says a measure of consistency between the two studies is important, because “reproducibility in science increases our confidence in the observed results.”

Just why Schwann and glial cells appear to be targets of cell phone radiation is not clear. David Carpenter, a physician who directs the Institute for Health and the Environment at the University at Albany, S.U.N.Y., explained the purpose of these cells is to insulate nerve fibers throughout the body. These are electrical systems, so that may be some sort of factor, he wrote in an e-mail. “But this is only speculation.”

A few epidemiology studies have reported higher rates of tumors inside the skull among people who use cell phones heavily for 10 years or more. Of particular concern are benign Schwann cell tumors called acoustic neuromas, which affect nerve cells connecting the inner ear with structures inside the brain. These growths can in some instances progress to malignant cancer with time. But other studies have found no evidence of acoustic neuromas or brain tumors in heavy cell phone users.

Samet adds a major challenge now would be to draw a biologically relevant connection between acoustic neuromas and other glial tumors in the brains of humans with Schwann tumors in rat hearts. “The mechanism is uncertain,” he says. “There’s a lot of information we still need to fill in.”

Since 2011 RF radiation has been classified as a Group 2B “possible” human carcinogen by the International Agency on Cancer (IARC), an agency of the World Health Organization. Based on the new animal findings, and limited epidemiological evidence linking heavy and prolonged cell phone use with brain gliomas in humans, Fiorella Belpoggi, director of research at the Ramazzini Institute and the study’s lead author, says IARC should consider changing the RF radiation designation to a “probable” human carcinogen. Even if the hazard is low, billions of people are exposed, she says, alluding to the estimated number of wireless subscriptions worldwide. Véronique Terrasse, an IARC spokesperson, says a reevaluation may occur after the NTP delivers its final report.

Stephen Chanock, who directs the Division of Cancer Epidemiology and Genetics at the National Cancer Institute, remains skeptical, however. Cancer monitoring by the institute and other organizations has yet to show increasing numbers of brain tumors in the general population, he says. Tracking of benign brain tumors, such as acoustic neuromas, was initiated in 2004 by investigators at the institute’s Surveillance, Epidemiology and End Results program, which monitors and publishes statistics on cancer incidence rates. According to Chanock’s spokesperson, the acoustic neuroma data “haven’t accumulated to the point that we can say something meaningful about them.”

Asked if brain cancer’s long latency might explain why higher rates in the population have not appeared yet, Chanock says, “Cell phones have been around a long time. We are by no means dismissing the evidence, and the Ramazzini study raises interesting questions. But it has to be factored in with other reports, and this is still work in progress.”

Epidemiology studies investigating cell phone use patterns with human cancer risk have produced inconsistent results. Some studies enrolled people who already had tumors with suspected links to RF radiation, such as gliomas, acoustic neuromas and salivary gland tumors. Researchers compared the self-reported cell phone use habits of the cancer patients with those of other people who did not have the same diseases. Other studies enrolled people while they were still healthy, and then followed them over time to see if new cancer diagnoses tracked with how they used cell phones. All the epidemiology studies, however, have troubling limitations, including that enrolled subjects often do not report their cell phone use habits accurately on questionnaires.

In a February 2 statement, Jeffrey Shuren, director of the FDA’s Center for Devices and Radiological Health, wrote that despite the NTP study’s results, the combined evidence on RF exposure and human cancer—which by now amounts to hundreds of studies—has “given us confidence that the current safety limits for cell phone radiation remain acceptable for protecting the public health.” Chonock says that for him, evidence from the Ramazzini study does not alter that conclusion. “We continue to agree with the FDA statement,” he says.

UW researcher’s wake-up call on cellphone radiation is finally getting heard

Can radiation from cellphones damage DNA in our brains? When a UW researcher found disturbing data, funding became tight and one industry leader threatened legal action.

By Rob Harrill | March 2005 issue

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H enry Lai has a vivid recollection of his introduction to the politics of big science. It was 1994, and he had just received a message from the National Institutes of Health, which was funding work he was doing on the effects of microwave radiation, similar to that emitted by cellular phones, on the brain. He and UW colleague Narendra “N.P.” Singh had results indicating that the radiation could cause DNA damage in brain cells.

The news was apparently unwelcome in some quarters.

Someone had called the NIH to report that Lai was misusing his research funding by doing work not specified in the grant (the grant didn’t mention DNA). And the agency wanted to know what was going on.

“It really scared the hell out of me,” says Lai, a research professor in the UW’s Department of Bioengineering who earned his Ph.D. from the UW in 1977. “I was awake all night, worrying about it, wondering what to do.”

In the morning, he sent a fax to the agency, explaining how the research fell within the parameters of the grant. The NIH accepted his explanation and assured him that all was well. “They are usually fairly liberal in that regard,” Lai says. “To do otherwise would stifle the scientific process.”

The incident, he says, was only the beginning in a David-and-Goliath conflict pitting him — and other researchers — against an emerging technology that would rapidly become one of the most lucrative and powerful businesses on the planet: the cell phone industry.

UW Research Professor Henry Lai with a few of his laboratory rats. Photo by Kathy Sauber.

The controversy goes back to a study by Lai and Singh published in a 1995 issue of Bioelectromagnetics . They found an increase in damaged DNA in the brain cells of rats after a single two-hour exposure to microwave radiation at levels considered “safe” by government standards.

The idea behind that study was relatively simple: expose rats to microwave radiation similar to that emitted by cell phones, then examine their brain cells to see if any DNA damage resulted. Such damage is worrisome because DNA carries the body’s genetic code and breaks, if not repaired properly, could lead to mutations and even cancer.

When the study was first published, a spokesperson from the cell phone industry said it was “not very relevant because they didn’t use the [same] cellular frequency or cellular power.”

True, responds Lai. But effects at one frequency could also happen at another frequency, and the exposure level in the experiment was actually lower than one can get from a cell phone. What it indicated was potential problems with the type of radiation the devices emit.

To this day, the cell phone industry continues to dispute Lai and Singh’s findings.

“I don’t believe any of those studies have ever been replicated,” says Joe Farren, director of public affairs for CTIA-The Wireless Association, a Washington, D.C.-based industry consortium that provides $1 million a year in funding for cell phone research. “We believe you should follow the science. The science to date shows there is not a health risk associated with the use of any wireless device.”

Technically, Farren may be correct about Lai’s study, but that’s because no one has tried to replicate Lai and Singh’s exact experiment. And a 1998 experiment that used common cell phone frequencies did find biological damage in some cases. More recently, a European research effort by 12 groups in seven countries also documented DNA damage from cell phone radiation.

“ It’s all about science, politics and money, and not necessarily in that order. ”

Louis Slesin, editor of Microwave News

While Lai is the first to say there are “no solid answers” to the controversy over cell phones and DNA damage, there is “cause for concern” and more work needs to be done. Instead, Lai says, he and his colleague have been the focus of a campaign to discredit their research. Consider:

• Internal documents from Motorola in the 1990s point to an organized plan to “war-game” Lai’s work.
• When a scientist in California published results that seemed to support Lai’s findings, he lost research funding and eventually left the field.
• At one point, the director of a group created to manage $25 million in industry-donated research money sent a memo to then-UW President Richard McCormick saying that Lai and Singh should be fired.
• Federal money for scientific investigation in the field has dried up, supplanted by funding from the industry-funding that Lai and others say can come with restrictions so oppressive they hamper scientific inquiry.

The stakes, both in terms of potential ramifications and profits, are high. According to consulting firm Deloitte & Touche, the global wireless market is expected to grow to two billion subscribers by the end of this year. An overall dollar figure for the industry would easily be in the hundreds of billions, according to Louis Slesin, who as editor of Microwave News has followed the ins and outs of research in the field of bioelectromagnetics for more than 20 years.

“It’s all about science, politics and money, and not necessarily in that order,” Slesin says. “Henry and N.P. had the courage to buck the system, and they have paid dearly for that.”

In preparing this article, some industry officials didn’t return phone calls asking about Lai’s work and the controversy surrounding it. Others said they didn’t have specific knowledge of the original study and the events it set into motion — it was more than 10 years ago — but they characterized such research as outside mainstream findings, which they say show that wireless technology is safe.

“ I’m just a simple scientist trying to do my research. ”

Still others maintain that possible hazards from recent studies could be discounted because those studies focus on older analog phones, which send out a steady wave of radiation. Newer digital phones operate at a lower intensity, sending out a pulsed stream.

A Swedish study published last fall that tracked 750 subjects who had used cell phones for at least 10 years made note of that difference, and included the following caveat:

“At the time the study was conducted, only analog mobile phones had been in use for more than 10 years and therefore we cannot determine if the results are confined to the use of analog phones or if the results would be similar after long-term use of digital phones.”

But it would be a mistake to use that to support a stance that digital phones are proven safe, according to Slesin. The problem, he says, is that pulsed radiation is more likely than continuous wave radiation to have an effect on living things.

“There is a lot of work out there showing that digital signals are more biologically active,” Slesin says. “At this point, no one knows whether the enhanced biological activity might compensate for the weaker signals.”

Lai, a soft-spoken bespectacled man with an understated sense of humor — he once deadpanned to a national television reporter that the most difficult part of his research involved getting the rats to use tiny cell phones — still expresses surprise at being at the center of the ongoing, swirling debate.

“I’m just a simple scientist trying to do my research,” he says. He sees the path that led to controversy as marked by chance and serendipity.

A Hong Kong native, Lai earned his bachelor’s degree in physiology from McGill University in Montreal and came to the UW in 1972 to do graduate work. He earned his doctoral degree in psychology and did post-doc work in pharmacology with Akira Horita. His initial research involved the effects of alcohol on the brain. He also worked on a new compound to treat schizophrenia.

A shift came in 1979. Bill Guy, UW emeritus professor and a pioneer in the field of radio wave physics, offered Lai a chance to do research on microwaves through a grant from the Office of Naval Research.

According to internal documents that later came to light, Motorola started working behind the scenes to minimize any damage Lai’s research might cause.

The pair first examined whether microwaves can affect drug interactions (they can), then if there appears to be an effect on learning (there does). Then, in the early ’90s, Singh arrived in Seattle. He approached Lai about joining his lab. “He was an expert on DNA damage,” Lai recalls. “I said, ‘Well, why not?’”

Singh is one of the world’s foremost experts on a DNA analysis called the “comet assay.” The assay gets its name from the appearance of a damaged cell. First, the cell is set in a gel and “lysed” or punctured. Then an electric current is run across the cell. When strands of DNA break, the broken pieces are charged. The electric current causes those pieces to migrate through the gel. As a result, a damaged cell takes on the appearance of a comet, with the bits of damaged DNA forming the tail. The longer the tail, the more damage has resulted.

With Singh’s expertise now at hand, Lai decided to look at how microwaves affect DNA. Lai and Singh compared rats exposed to a low dose of microwave radiation for two hours to a control group of rats that spent the same amount of time in the exposure device, but didn’t receive any radiation. The exposed rats showed about a 30 percent increase in single -strand breaks in brain cell DNA compared to the control group.

As Lai and Singh sought funding to conduct follow-up studies, word of the research began to get out. According to internal documents that later came to light, Motorola started working behind the scenes to minimize any damage Lai’s research might cause. In a memo and a draft position paper dated Dec. 13, 1994, officials talked about how they had “war-gamed the Lai-Singh issue” and were in the process of lining up experts who would be willing to point out weaknesses in Lai’s study and reassure the public. This was before the study was published in 1995.

A couple of years later, Lai got money from Wireless Technology Research (WTR), a group organized by CTIA to administer $25 million in industry research funding, to do some follow-up studies. But the conditions that came with the funding were restrictive. So much so that Lai and Singh wrote an open letter to Microwave News recounting their experience. The letter, published in 1999, cited irregularities in processes and procedures that the two called “highly suspicious.”

“In the 20 years or so that we have conducted experiments, for a variety of funding agencies, we have never encountered anything like this in the management of a scientific contract,” the two wrote.

Recent findings from overseas, more than 10 years after Lai’s work, seem to finally be providing support for a closer look at cell phone radiation.

WTR leader George Carlo responded with a six-page letter to then-UW President Richard McCormick, complaining of the “libelous” letter to Microwave News and “a pattern of slanderous conduct by these men over the past several years.” The letter closed with a threat of legal action and stated that Lai and Singh should be fired from the project. An answering letter from Vice Provost Steven Olswang stated that the University “encourages legitimate academic discourse” and would not intervene in the dispute.

While Lai and Singh were attempting to do their industry-funded follow-up study, the industry was looking for another opinion. Motorola approached Jerry Phillips, a researcher who worked in a lab at the Veteran’s Administration Medical Center in Loma Linda, Calif. He was investigating electromagnetic fields and their biological effects. The lab had done work with Motorola before, and Phillips was interested. He made a proposal and was funded.

He sent people to Seattle to learn how to do the comet assay. And he decided to expose the animals in his experiment to actual cell phone frequencies. What they found were increases in DNA damage at some levels of exposure and decreases at others.

“That’s not unusual,” Phillips says. “It happens with chemicals. One dose can do one thing, while a higher or lower dose does the opposite. In this case, if you produce a little bit of DNA damage, you are stimulating the repair mechanisms and you could actually see a net decrease because the repair will be done. However, if you overwhelm the repair mechanism, then you could see an increase.

“Based on the data, I told them that we need to start looking at repair mechanisms,” Phillips recalls.

Motorola disagreed. Phillips says he was told the results were not ready for publication, was encouraged to do more work, and was offered additional money to continue the experiment.

“I said as much as I would like the money, this part of the study is done,” he recalls. “I said it’s time to move on.” The study was published in Nov. 1998. Once the findings were released, Phillips’ source of funding dried up.

Since then, another group, working out of Washington University in St. Louis with industry funding, has tried to replicate the experiment, but without success. According to Lai and Phillips, that group is doing the study differently, including using a different technique to gauge DNA damage.

“They haven’t properly replicated the work that Henry did, or that I did,” Phillips says.

In the meantime, recent findings from overseas, more than 10 years after Lai’s work, seem to finally be providing support for a closer look at cell phone radiation.

“ Everyone uses the analogy of the tobacco industry and what happened there. It’s like letting the fox watch the henhouse. ”

Last fall, the journal Epidemiology published research results from a Swedish group that showed an increase in a rare type of non-cancerous brain tumor among cell phone users on the side of the head where the phone was most often held.

In December, a pan-European organization released results from an extensive four-year study carried out by 12 research groups in seven countries. Known as the REFLEX study, that research found significant increases in DNA damage in human and animal cells exposed to cell phone radiation in the laboratory. While not a cause for alarm, the results, which have yet to be published, underline the need for further study, scientists said.

A spokeswoman for the UK-based Mobile Operators Association called the results “preliminary,” adding that, “It is not possible to draw conclusions from this preliminary data.”

In 2000, Sir William Stewart, former chair of a British group that looked into the cell phone debate issued a report urging “a precautionary stance” while scientific data is gathered. This January he repeated that warning, adding that children should not use the devices for the time being.

Industry spokesman Farren says his organization sticks to its position. “Any official precautionary measures need to be based on the science,” he says. “The majority of studies have shown there are no health effects.”

It’s a point well taken, Lai says. However, what the science seems to say depends on how you quantify it.

Lai says there have been about 200 studies on the biological effects of cell-phone-related radiation. If you put all the ones that say there is a biological effect on one side and those that say there is no effect on the other, you’d have two piles roughly equal in size. The research splits about 50-50.

“That, in and of itself, is alarming,” Lai says. But it’s not the whole story. If you divide up the same 200 studies by who sponsored the research, the numbers change.

“When you look at the non-industry sponsored research, it’s about three to one — three out of every four papers shows an effect,” Lai says. “Then, if you look at the industry-funded research, it’s almost opposite — only one out of every four papers shows an effect.”

The problem, he adds, is that there is no longer funding available in the United States that isn’t attached to the industry. Lai, for one, refuses to take any more industry money.

“There are too many strings attached,” he maintains. “Everyone uses the analogy of the tobacco industry and what happened there. It’s like letting the fox watch the henhouse.” While the FDA administers cell phone radiation studies, the money comes from the industry, he adds.

Microwave News Editor Slesin says he has pondered why government funding isn’t available. His hypothesis is that it’s a matter of attitude.

“There is a view out there among many scientists that this is just impossible — the radiation is too weak and there cannot be any effects,” Slesin says. “We all know that ionizing radiation is bad. Ions are more reactive, there’s no doubt it can lead to cancer, it’s nasty stuff.”

The people who work with ionizing radiation see EMF radiation — that from electromagnetic fields — as a 97-pound weakling, he continues. They believe it’s not capable of doing anything.

“Yet, when you see effects like Henry reported, especially at the low power intensities, you have to ask what is going on to cause this?” he says. “As long as that attitude remains unchanged, you won’t get more funding and you don’t get anywhere.”

“ We are making some fundamental changes to the electromagnetic environment in which we live. ”

As a result, many U.S. scientists have moved on, either focusing on other areas or leaving the research arena altogether, relying on the rest of the world to pick up the slack. In Lai’s case, he is pursuing other research directions, where he can get funding. The most promising involves artemisinin, a derivative from the wormwood plant currently used to treat malaria. Lai’s research shows it has promise as a powerful anti-cancer agent. Late last year, the UW licensed the technology to a Chinese pharmaceutical company that plans to take it to human trials and, if successful, to market.

After what happened in Loma Linda, Phillips and his wife left research altogether. They now live in Colorado Springs, Colo., where he works for a company that develops science curricula. “I do have a lot of regret for those lost opportunities,” Phillips says. “We were really in a position to develop some good basic understandings of how radio frequency affects biological systems.”

It’s an issue that desperately needs to be explored, according to Slesin. Right now, a solid understanding doesn’t exist. If anyone says they absolutely have the answer, he cautions, absolutely don’t believe them. “We are swimming in uncertainty.”

And the issue becomes increasingly relevant with each passing day.

“We are making some fundamental changes to the electromagnetic environment in which we live,” Slesin continues. “Soon entire cities will be online so you can take your laptop anywhere and be on the Internet. What that means is we will all be exposed to electromagnetic radiation 24/7. I don’t know if there’s a problem, but I think we owe it to society to find out.”

In the meantime, Lai prefers to err on the side of caution. He doesn’t use a cell phone and requires that cell-savvy family members use headsets. He doesn’t see the problem as intractable, just one that needs serious attention. We engineered the technology, he says, and he’s confident that we can engineer our way out of any problems. But first, we need to take a close look at the data and admit that there may be a problem.

Either way, the answers will come, given time, Lai says. The question is will we get those answers in the way we want?

“We see effects, but we don’t know what the consequences are,” Lai says. “With so many people using cell phones, we will eventually know. The largest experiment in the history of the world is already under way. We will know, in about 10 or 15 years, maybe.”

Old medicine, new cure?

As funding for cellphone-related research has become increasingly scarce in this country, University of Washington Bioengineer Henry Lai has pursued other areas of interest. Chief among them is a foray into the ancient arts of Chinese folk medicine to find a promising potential treatment for cancer.

Lai and colleague Narendra Singh have exploited the chemical properties of a wormwood derivative called artemisinin to target cancer cells, with surprisingly effective results. Last fall, the UW TechTransfer Office signed a licensing agreement with a Chinese pharmaceutical company to develop a group of artemisinin-based compounds for possible use in humans.

The compounds are promising, officials say, but medical applications are still years away. Lai says he became interested in artemisinin about 10 years ago. The chemical isn’t new — wormwood was apparently used by the Chinese thousands of years ago to combat malaria.

The treatment became lost, but was rediscovered in the 1970s in an ancient record listing medical remedies. It’s now widely used to fight malaria in Asia and Africa.

The chemical helps control malaria because it reacts with the high iron concentrations found in the single-cell malaria parasite. When artemisinin comes into contact with iron, a chemical reaction ensues, spawning charged atoms that chemists call “free radicals.” The free radicals attack cell membranes and other molecules, breaking them apart and killing the single-cell parasite.

Lai began to wonder if the process might work with cancer, too. “Cancer cells need a lot of iron to replicate DNA when they divide,” Lai explains. “As a result, cancer cells have much higher iron concentrations than normal cells.”

Most recently, Lai and Singh looked at a method that involves the use of the protein transferrin, to which the researchers bound artemisinin at the molecular level. Transferrin is an iron-carrying protein found in blood, and it is transported into cells via transferrin receptors on the cell’s surface.

Iron-hungry cancer cells take in the transferrin without detecting the attached artemisinin. “We call it a Trojan horse because a cancer cell recognizes transferrin as a natural, harmless protein and picks up the tagged compound without knowing that a bomb — artemisinin — is hidden inside,” Lai says.

According to a study published in January in the journal Life Sciences , the compound is 34,000 times more effective in selecting and killing cancer cells than normal cells. Artemisinin alone is 100 times more effective.

“So we’ve greatly enhanced the selectivity,” Lai said.

Rob Harrill is the engineering writer in the UW's College of Engineering.

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Frequently Asked Questions about Cell Phones and Your Health

There is no scientific evidence that provides a definite answer to that question. Some organizations recommend caution in cell phone use. More research is needed before we know if using cell phones causes health effects.

Yes – cell phones and cordless phones use radiofrequency radiation (RF) to send signals. RF is different from other types of radiation (like x-rays) that we know can be harmful. We don’t know for sure if RF radiation from cell phones can cause health problems years later. The International Agency for Research on Cancer (IARC) has classified RF radiation as a “possible human carcinogen.” (A carcinogen is an agent that causes cancer.)

At this time we do not have the science to link health problems to cell phone use. Scientific studies are underway to determine whether cell phone use may cause health effects. It is also important to consider the benefits of cell phones. Their use can be valuable in an urgent or emergency situation – and even save lives.

If you are worried about cell phone use, follow the tips below.

Why has the information on this page been updated?

CDC has not changed its position on health effects associated with the use of cell phones. The agency updated these cell phone FAQs in June 2014 as part of efforts to ensure that health information for the public followed best practices, including the use of plain, easy-to-understand, language. During this process, revisions were introduced which inadvertently led some visitors to the web page to believe that a change in position had occurred. The corrected FAQs are now available on this page.

CDC announces changes in public health policy and recommendations through publication in the peer-reviewed literature, usually accompanied by outreach to partners and a media announcement. We apologize for any confusion that resulted from our efforts to ensure that agency information is presented in easy-to-understand language. 

View previous version of FAQ pdf icon [PDF – 735K]

To reduce radio frequency radiation near your body:

• Get a hands-free headset that connects directly to your phone.
• Use speaker-phone more often.
• In the past, RF interfered with the operation of some pacemakers. If you have a pacemaker and are concerned about how your cell phone use may affect it, contact your health care provider.

Scientists are continuing to study the possible health effects of cell phone use. For example, the World Health Organization (WHO) is currently looking into how cell phones may affect:

• Some types of tumors (a lump or growth)

In the News: Acoustic Neuroma

Where can i get more information about cell phones and health.

For more information, visit:

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• The Food and Drug Administration external icon

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Radio Frequency Radiation and Cell Phones

Radiation is energy that comes from a source and travels through space. For example, an electric heater operates by heating metal wires and the wires radiate that energy as heat (infrared radiation).

Radio frequency radiation is a type of electromagnetic radiation , which is a combination of electric and magnetic fields that move through space together as waves. Electromagnetic radiation falls into two categories:

Generally, when people hear the word radiation , they’re thinking of ionizing radiation , like X-rays and gamma rays. Ionizing radiation carries enough energy to break chemical bonds, knock electrons out of atoms, and cause direct damage to cells in organic matter. In fact, ionizing radiation carries more than a billion times more energy than does non-ionizing radiation. A little ionizing radiation can be used to produce x-ray images for diagnosis. A lot of ionizing radiation is needed to kill cancer cells in radiation therapy.

By contrast, non-ionizing radiation does not have enough energy to break chemical bonds or strip electrons from atoms. Scientific consensus shows that non-ionizing radiation is not a carcinogen and, at or below the radio frequency exposure limits set by the FCC, non-ionizing radiation has not been shown to cause any harm to people.

Cell phones emit low levels of non-ionizing radiation while in use. The type of radiation emitted by cell phones is also referred to as radio frequency (RF) energy. As stated by the National Cancer Institute , "there is currently no consistent evidence that non-ionizing radiation increases cancer risk in humans. The only consistently recognized biological effect of radiofrequency radiation in humans is heating."

For a more detailed description of radio frequency radiation, see Microwaves, Radio Waves, and Other Types of Radiofrequency Radiation from the American Cancer Society.

For more information about the electromagnetic spectrum, see NASA’s Tour of the Electromagnetic Spectrum .

For more information about radio frequency safety, see the FCC’s RF Safety FAQ .

Cell phones and cancer: New UC Berkeley study suggests cell phones sharply increase tumor risk

File of cell phone user. New UC Berkeley research draws link between cell phone use and increase risk of tumors. (Photo by Justin Sullivan/Getty Images).

BERKELEY, Calif. - New UC Berkeley research draws a strong link between cell phone radiation and tumors, particularly in the brain.

Researchers took a comprehensive look at statistical findings from 46 different studies around the globe and found that the use of a cell phone for more than 1,000 hours, or about 17 minutes a day over a ten year period, increased the risk of tumors by 60 percent.

Researchers also pointed to findings that showed cell phone use for 10 or more years doubled the risk of brain tumors.  

Joel Moskowitz, director of the Center for Family and Community Health with the UC Berkeley School of Public Health conducted the research in partnership with Korea’s National Cancer Center, and Seoul National University. Their analysis took a comprehensive look at statistical findings from case control studies from 16 countries including the U.S., Sweden, United Kingdom, Japan, Korea, and New Zealand.  

"Cell phone use highlights a host of public health issues and it has received little attention in the scientific community, unfortunately," said Moskowitz. 

Cell phone use has increasingly become part of people’s daily lives, especially with the emergence of smartphones. Recent figures from the Pew Research Center showed that 97% of Americans now own a cell phone of some kind.

This, as more and more people have become dependent on their mobile phones as an integral mode of communication. In fact, an increasing number of people have ditched their landlines at home, relying on their cell phone as their sole device for telephone communication. 

Figures from the Center for Disease Control and Prevention's National Center for Health Statistics found 61.8% of adults have decided to go wireless-only. 

With the increased use of mobile devices, the research has been vast on their potential link to cancer. The findings have varied and at times been controversial. 

Many studies looking into the health risks of cell phone use have been funded or partially funded by the cellular phone industry, which critics argue can skew research results. 

"Moskowitz emphasized that these studies have been controversial as it is a highly sensitive political topic with significant economic ramifications for a powerful industry," Berkeley Public Health noted. 

The position held by federal regulators point to a lack of evidence showing a direct link.

"To date, there is no consistent or credible scientific evidence of health problems caused by the exposure to radio frequency energy emitted by cell phones," the Food and Drug Administration stated on its website. 

The FDA also said that the Federal Communications Commission has set a limit on radio frequency energy that "remains acceptable for protecting the public health."

SEE ALSO: San Jose neighbors oppose 5G cell equipment installed feet from homes

UC Berkeley researchers noted that in 2017, California regulators alerted the public of potential health risks related to cell phone use, although some felt the warning did not go far enough.

In its alert, the California Department of Public Health said, "Although the science is still evolving, some laboratory experiments and human health studies have suggested the possibility that long-term, high use of cell phones may be linked to certain types of cancer and other health effects."

The agency also provided advice on how to reduce exposure, including keeping phones away from your body and carrying devices in a backpack, briefcase, or purse. Health experts said cell phones should not be held in a pocket, bra, or belt holster, as a phone’s antenna tries to stay connected with a cell tower whenever it’s on, emitting radio frequency (RF) energy even when not in use. 

A view of cellular communication towers in Emeryville, California. (Photo by Justin Sullivan/Getty Images)

Experts also suggested when not in use, putting the phone in airplane mode, which turns off cellular, Wi-Fi, and Bluetooth. 

When on a call, experts advised avoid holding the phone up to your head and instead use the speaker feature or a headset.

Experts also said you should reduce or avoid use of your phone when there’s only one or two bars displayed showing the strength of connectivity. "Cell phones put out more RF energy to connect with cell towers when the signal is weak," health officials noted.

That’s also true when using a mobile device in a fast-moving car, bus, or train because the phone emits more RF energy to maintain connections to avoid dropping calls as it switches connections from cell tower to cell tower.

Ultimately, when it comes to cell phones, "distance is your friend," Moskowitz said. "Keeping your cellphone 10 inches away from your body, as compared to one-tenth of an inch, results in a 10,000-fold reduction in exposure. So, keep your phone away from your head and body," he advised.

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Mobile phones have been around for decades, becoming widely accessible to the mainstream public in the 1980's. And as more people spend more time on the devices, researchers warned that could increase the risk of health problems related to their use. The study called for further in-depth research using exact data on the time spent on cell phones to confirm the latest findings.

Moskowitz, who has been researching and writing about the dangers of radiation from cell phones and cell towers for more than a decade, said publication of his findings have consistently led to increased calls for continued research. "…as soon as those stories went public in the media," he said, "I was contacted from survivors of cell phone radiation begging me to stay on this topic." 

This latest study has been published in the International Journal of Environmental Research and Public Health .

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Risks to Health and Well-Being From Radio-Frequency Radiation Emitted by Cell Phones and Other Wireless Devices

Anthony b. miller.

1 Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada

Margaret E. Sears

2 Ottawa Hospital Research Institute, Prevent Cancer Now, Ottawa, ON, Canada

L. Lloyd Morgan

3 Environmental Health Trust, Teton Village, WY, United States

Devra L. Davis

Lennart hardell.

4 The Environment and Cancer Research Foundation, Örebro, Sweden

Mark Oremus

5 School of Public Health and Health Systems, University of Waterloo, Waterloo, ON, Canada

Colin L. Soskolne

6 School of Public Health, University of Alberta, Edmonton, AB, Canada

7 Health Research Institute, University of Canberra, Canberra, ACT, Australia

Radiation exposure has long been a concern for the public, policy makers, and health researchers. Beginning with radar during World War II, human exposure to radio-frequency radiation 1 (RFR) technologies has grown substantially over time. In 2011, the International Agency for Research on Cancer (IARC) reviewed the published literature and categorized RFR as a “possible” (Group 2B) human carcinogen. A broad range of adverse human health effects associated with RFR have been reported since the IARC review. In addition, three large-scale carcinogenicity studies in rodents exposed to levels of RFR that mimic lifetime human exposures have shown significantly increased rates of Schwannomas and malignant gliomas, as well as chromosomal DNA damage. Of particular concern are the effects of RFR exposure on the developing brain in children. Compared with an adult male, a cell phone held against the head of a child exposes deeper brain structures to greater radiation doses per unit volume, and the young, thin skull's bone marrow absorbs a roughly 10-fold higher local dose. Experimental and observational studies also suggest that men who keep cell phones in their trouser pockets have significantly lower sperm counts and significantly impaired sperm motility and morphology, including mitochondrial DNA damage. Based on the accumulated evidence, we recommend that IARC re-evaluate its 2011 classification of the human carcinogenicity of RFR, and that WHO complete a systematic review of multiple other health effects such as sperm damage. In the interim, current knowledge provides justification for governments, public health authorities, and physicians/allied health professionals to warn the population that having a cell phone next to the body is harmful, and to support measures to reduce all exposures to RFR.

Introduction

We live in a generation that relies heavily on technology. Whether for personal use or work, wireless devices, such as cell phones, are commonly used around the world, and exposure to radio-frequency radiation (RFR) is widespread, including in public spaces ( 1 , 2 ).

In this review, we address the current scientific evidence on health risks from exposure to RFR, which is in the non-ionizing frequency range. We focus here on human health effects, but also note evidence that RFR can cause physiological and/or morphological effects on bees, plants and trees ( 3 – 5 ).

We recognize a diversity of opinions on the potential adverse effects of RFR exposure from cell or mobile phones and other wireless transmitting devices (WTDs) including cordless phones and Wi-Fi. The paradigmatic approach in cancer epidemiology, which considers the body of epidemiological, toxicological, and mechanistic/cellular evidence when assessing causality, is applied.

Carcinogenicity

Since 1998, the International Commission on Non-Ionizing Radiation Protection (ICNIRP) has maintained that no evidence of adverse biological effects of RFR exist, other than tissue heating at exposures above prescribed thresholds ( 6 ).

In contrast, in 2011, an expert working group of the International Agency for Research on Cancer (IARC) categorized RFR emitted by cell phones and other WTDs as a Group 2B (“possible”) human carcinogen ( 7 ).

Since the IARC categorization, analyses of the large international Interphone study, a series of studies by the Hardell group in Sweden, and the French CERENAT case-control studies, signal increased risks of brain tumors, particularly with ipsilateral use ( 8 ). The largest case-control studies on cell phone exposure and glioma and acoustic neuroma demonstrated significantly elevated risks that tended to increase with increasing latency, increasing cumulative duration of use, ipsilateral phone use, and earlier age at first exposure ( 8 ).

Pooled analyses by the Hardell group that examined risk of glioma and acoustic neuroma stratified by age at first exposure to cell phones found the highest odds ratios among those first exposed before age 20 years ( 9 – 11 ). For glioma, first use of cell phones before age 20 years resulted in an odds ratio (OR) of 1.8 (95% confidence interval [CI] 1.2–2.8). For ipsilateral use, the OR was 2.3 (CI 1.3-4.2); contralateral use was 1.9 (CI 0.9-3.7). Use of cordless phone before age 20 yielded OR 2.3 (CI 1.4–3.9), ipsilateral OR 3.1 (CI 1.6–6.3) and contralateral use OR 1.5 (CI 0.6–3.8) ( 9 ).

Although Karipidis et al. ( 12 ) and Nilsson et al. ( 13 ) found no evidence of an increased incidence of gliomas in recent years in Australia and Sweden, respectively, Karipidis et al. ( 12 ) only reported on brain tumor data for ages 20–59 and Nilsson et al. ( 13 ) failed to include data for high grade glioma. In contrast, others have reported evidence that increases in specific types of brain tumors seen in laboratory studies are occurring in Britain and the US:

• The incidence of neuro-epithelial brain cancers has significantly increased in all children, adolescent, and young adult age groupings from birth to 24 years in the United States ( 14 , 15 ).
• A sustained and statistically significant rise in glioblastoma multiforme across all ages has been described in the UK ( 16 ).

The incidence of several brain tumors are increasing at statistically significant rates, according to the 2010–2017 Central Brain Tumor Registry of the U.S . (CBTRUS) dataset ( 17 ).

• There was a significant increase in incidence of radiographically diagnosed tumors of the pituitary from 2006 to 2012 (APC = 7.3% [95% CI: 4.1%, 10.5%]), with no significant change in incidence from 2012 to 2015 ( 18 ).
• Meningioma rates have increased in all age groups from 15 through 85+ years.
• Nerve sheath tumor (Schwannoma) rates have increased in all age groups from age 20 through 84 years.
• Vestibular Schwannoma rates, as a percentage of nerve sheath tumors, have also increased from 58% in 2004 to 95% in 2010-2014.

Epidemiological evidence was subsequently reviewed and incorporated in a meta-analysis by Röösli et al. ( 19 ). They concluded that overall, epidemiological evidence does not suggest increased brain or salivary gland tumor risk with mobile phone (MP) use, although the authors admitted that some uncertainty remains regarding long latency periods (>15 years), rare brain tumor subtypes, and MP usage during childhood. Of concern is that these analyses included cohort studies with poor exposure classification ( 20 ).

In epidemiological studies, recall bias can play a substantial role in the attenuation of odds ratios toward the null hypothesis. An analysis of data from one large multicenter case-control study of RFR exposure, did not find that recall bias was an issue ( 21 ). In another multi-country study it was found that young people can recall phone use moderately well, with recall depending on the amount of phone use and participants' characteristics ( 22 ). With less rigorous querying of exposure, prospective cohort studies are unfortunately vulnerable to exposure misclassification and imprecision in identifying risk from rare events, to the point that negative results from such studies are misleading ( 8 , 23 ).

Another example of disparate results from studies of different design focuses on prognosis for patients with gliomas, depending upon cell phone use. A Swedish study on glioma found lower survival in patients with glioblastoma associated with long term use of wireless phones ( 24 ). Ollson et al. ( 25 ), however, reported no indication of reduced survival among glioblastoma patients in Denmark, Finland and Sweden with a history of mobile phone use (ever regular use, time since start of regular use, cumulative call time overall or in the last 12 months) relative to no or non-regular use. Notably, Olsson et al. ( 25 ) differed from Carlberg and Hardell ( 24 ) in that the study did not include use of cordless phones, used shorter latency time and excluded patients older than 69 years. Furthermore, a major shortcoming was that patients with the worst prognosis were excluded, as in Finland inoperable cases were excluded, all of which would bias the risk estimate toward unity.

In the interim, three large-scale toxicological (animal carcinogenicity) studies support the human evidence, as do modeling, cellular and DNA studies identifying vulnerable sub-groups of the population.

The U.S. National Toxicology Program (NTP) (National Toxicology Program ( 26 , 27 ) has reported significantly increased incidence of glioma and malignant Schwannoma (mostly on the nerves on the heart, but also additional organs) in large animal carcinogenicity studies with exposure to levels of RFR that did not significantly heat tissue. Multiple organs (e.g., brain, heart) also had evidence of DNA damage. Although these findings have been dismissed by the ICNIRP ( 28 ), one of the key originators of the NTP study has refuted the criticisms ( 29 ).

A study by Italy's Ramazzini Institute has evaluated lifespan environmental exposure of rodents to RFR, as generated by 1.8 GHz GSM antennae of cell phone radio base stations. Although the exposures were 60 to 6,000 times lower than those in the NTP study, statistically significant increases in Schwannomas of the heart in male rodents exposed to the highest dose, and Schwann-cell hyperplasia in the heart in male and female rodents were observed ( 30 ). A non-statistically significant increase in malignant glial tumors in female rodents also was detected. These findings with far field exposure to RFR are consistent with and reinforce the results of the NTP study on near field exposure. Both reported an increase in the incidence of tumors of the brain and heart in RFR-exposed Sprague-Dawley rats, which are tumors of the same histological type as those observed in some epidemiological studies on cell phone users.

Further, in a 2015 animal carcinogenicity study, tumor promotion by exposure of mice to RFR at levels below exposure limits for humans was demonstrated ( 31 ). Co-carcinogenicity of RFR was also demonstrated by Soffritti and Giuliani ( 32 ) who examined both power-line frequency magnetic fields as well as 1.8 GHz modulated RFR. They found that exposure to Sinusoidal-50 Hz Magnetic Field (S-50 Hz MF) combined with acute exposure to gamma radiation or to chronic administration of formaldehyde in drinking water induced a significantly increased incidence of malignant tumors in male and female Sprague Dawley rats. In the same report, preliminary results indicate higher incidence of malignant Schwannoma of the heart after exposure to RFR in male rats. Given the ubiquity of many of these co-carcinogens, this provides further evidence to support the recommendation to reduce the public's exposure to RFR to as low as is reasonably achievable.

Finally, a case series highlights potential cancer risk from cell phones carried close to the body. West et al. ( 33 ) reported four “extraordinary” multifocal breast cancers that arose directly under the antennae of the cell phones habitually carried within the bra, on the sternal side of the breast (the opposite of the norm). We note that case reports can point to major unrecognized hazards and avenues for further investigation, although they do not usually provide direct causal evidence.

In a study of four groups of men, of which one group did not use mobile phones, it was found that DNA damage indicators in hair follicle cells in the ear canal were higher in the RFR exposure groups than in the control subjects. In addition, DNA damage increased with the daily duration of exposure ( 34 ).

Many profess that RFR cannot be carcinogenic as it has insufficient energy to cause direct DNA damage. In a review, Vijayalaxmi and Prihoda ( 35 ) found some studies suggested significantly increased damage in cells exposed to RF energy compared to unexposed and/or sham-exposed control cells, others did not. Unfortunately, however, in grading the evidence, these authors failed to consider baseline DNA status or the fact that genotoxicity has been poorly predicted using tissue culture studies ( 36 ). As well funding, a strong source of bias in this field of enquiry, was not considered ( 37 ).

Children and Reproduction

As a result of rapid growth rates and the greater vulnerability of developing nervous systems, the long-term risks to children from RFR exposure from cell phones and other WTDs are expected to be greater than those to adults ( 38 ). By analogy with other carcinogens, longer opportunities for exposure due to earlier use of cell phones and other WTDs could be associated with greater cancer risks in later life.

Modeling of energy absorption can be an indicator of potential exposure to RFR. A study modeling the exposure of children 3–14 years of age to RFR has indicated that a cell phone held against the head of a child exposes deeper brain structures to roughly double the radiation doses (including fluctuating electrical and magnetic fields) per unit volume than in adults, and also that the marrow in the young, thin skull absorbs a roughly 10-fold higher local dose than in the skull of an adult male ( 39 ). Thus, pediatric populations are among the most vulnerable to RFR exposure.

The increasing use of cell phones in children, which can be regarded as a form of addictive behavior ( 40 ), has been shown to be associated with emotional and behavioral disorders. Divan et al. ( 41 ) studied 13,000 mothers and children and found that prenatal exposure to cell phones was associated with behavioral problems and hyperactivity in children. A subsequent Danish study of 24,499 children found a 23% increased odds of emotional and behavioral difficulties at age 11 years among children whose mothers reported any cell phone use at age 7 years, compared to children whose mothers reported no use at age 7 years ( 42 ). A cross-sectional study of 4,524 US children aged 8–11 years from 20 study sites indicated that shorter screen time and longer sleep periods independently improved child cognition, with maximum benefits achieved with low screen time and age-appropriate sleep times ( 43 ). Similarly, a cohort study of Swiss adolescents suggested a potential adverse effect of RFR on cognitive functions that involve brain regions mostly exposed during mobile phone use ( 44 ). Sage and Burgio et al. ( 45 ) posit that epigenetic drivers and DNA damage underlie adverse effects of wireless devices on childhood development.

RFR exposure occurs in the context of other exposures, both beneficial (e.g., nutrition) and adverse (e.g., toxicants or stress). Two studies identified that RFR potentiated adverse effects of lead on neurodevelopment, with higher maternal use of mobile phones during pregnancy [1,198 mother-child pairs, ( 46 )] and Attention Deficit Hyper-activity Disorder (ADHD) with higher cell phone use and higher blood lead levels, in 2,422 elementary school children ( 47 ).

A study of Mobile Phone Base Station Tower settings adjacent to school buildings has found that high exposure of male students to RFR from these towers was associated with delayed fine and gross motor skills, spatial working memory, and attention in adolescent students, compared with students who were exposed to low RFR ( 48 ). A recent prospective cohort study showed a potential adverse effect of RFR brain dose on adolescents' cognitive functions including spatial memory that involve brain regions exposed during cell phone use ( 44 ).

In a review, Pall ( 49 ) concluded that various non-thermal microwave EMF exposures produce diverse neuropsychiatric effects. Both animal research ( 50 – 52 ) and human studies of brain imaging research ( 53 – 56 ) indicate potential roles of RFR in these outcomes.

Male fertility has been addressed in cross-sectional studies in men. Associations between keeping cell phones in trouser pockets and lower sperm quantity and quality have been reported ( 57 ). Both in vivo and in vitro studies with human sperm confirm adverse effects of RFR on the testicular proteome and other indicators of male reproductive health ( 57 , 58 ), including infertility ( 59 ). Rago et al. ( 60 ) found significantly altered sperm DNA fragmentation in subjects who use mobile phones for more than 4 h/day and in particular those who place the device in the trousers pocket. In a cohort study, Zhang et al. ( 61 ) found that cell phone use may negatively affect sperm quality in men by decreasing the semen volume, sperm concentration, or sperm count, thus impairing male fertility. Gautam et al. ( 62 ) studied the effect of 3G (1.8–2.5 GHz) mobile phone radiation on the reproductive system of male Wistar rats. They found that exposure to mobile phone radiation induces oxidative stress in the rats which may lead to alteration in sperm parameters affecting their fertility.

Related Observations, Implications and Strengths of Current Evidence

An extensive review of numerous published studies confirms non-thermally induced biological effects or damage (e.g., oxidative stress, damaged DNA, gene and protein expression, breakdown of the blood-brain barrier) from exposure to RFR ( 63 ), as well as adverse (chronic) health effects from long-term exposure ( 64 ). Biological effects of typical population exposures to RFR are largely attributed to fluctuating electrical and magnetic fields ( 65 – 67 ).

Indeed, an increasing number of people have developed constellations of symptoms attributed to exposure to RFR (e.g., headaches, fatigue, appetite loss, insomnia), a syndrome termed Microwave Sickness or Electro-Hyper-Sensitivity (EHS) ( 68 – 70 ).

Causal inference is supported by consistency between epidemiological studies of the effects of RFR on induction of human cancer, especially glioma and vestibular Schwannomas, and evidence from animal studies ( 8 ). The combined weight of the evidence linking RFR to public health risks includes a broad array of findings: experimental biological evidence of non-thermal effects of RFR; concordance of evidence regarding carcinogenicity of RFR; human evidence of male reproductive damage; human and animal evidence of developmental harms; and limited human and animal evidence of potentiation of effects from chemical toxicants. Thus, diverse, independent evidence of a potentially troubling and escalating problem warrants policy intervention.

Challenges to Research, From Rapid Technological Advances

Advances in RFR-related technologies have been and continue to be rapid. Changes in carrier frequencies and the growing complexity of modulation technologies can quickly render “yesterdays” technologies obsolete. This rapid obsolescence restricts the amount of data on human RFR exposure to particular frequencies, modulations and related health outcomes that can be collected during the lifespan of the technology in question.

Epidemiological studies with adequate statistical power must be based upon large numbers of participants with sufficient latency and intensity of exposure to specific technologies. Therefore, a lack of epidemiological evidence does not necessarily indicate an absence of effect, but rather an inability to study an exposure for the length of time necessary, with an adequate sample size and unexposed comparators, to draw clear conclusions. For example, no case-control study has been published on fourth generation (4G; 2–8 GHz) Long-term Evolution (LTE) modulation, even though the modulation was introduced in 2010 and achieved a 39% market share worldwide by 2018 ( 71 ).

With this absence of human evidence, governments must require large-scale animal studies (or other appropriate studies of indicators of carcinogenicity and other adverse health effects) to determine whether the newest modulation technologies incur risks, prior to release into the marketplace. Governments should also investigate short-term impacts such as insomnia, memory, reaction time, hearing and vision, especially those that can occur in children and adolescents, whose use of wireless devices has grown exponentially within the past few years.

The Telecom industry's fifth generation (5G) wireless service will require the placement of many times more small antennae/cell towers close to all recipients of the service, because solid structures, rain and foliage block the associated millimeter wave RFR ( 72 ). Frequency bands for 5G are separated into two different frequency ranges. Frequency Range 1 (FR1) includes sub-6 GHz frequency bands, some of which are bands traditionally used by previous standards, but has been extended to cover potential new spectrum offerings from 410 to 7,125 MHz. Frequency Range 2 (FR2) includes higher frequency bands from 24.25 to 52.6 GHz. Bands in FR2 are largely of millimeter wave length, these have a shorter range but a higher available bandwidth than bands in the FR1. 5G technology is being developed as it is also being deployed, with large arrays of directional, steerable, beam-forming antennae, operating at higher power than previous technologies. 5G is not stand-alone—it will operate and interface with other (including 3G and 4G) frequencies and modulations to enable diverse devices under continual development for the “internet of things,” driverless vehicles and more ( 72 ).

Novel 5G technology is being rolled out in several densely populated cities, although potential chronic health or environmental impacts have not been evaluated and are not being followed. Higher frequency (shorter wavelength) radiation associated with 5G does not penetrate the body as deeply as frequencies from older technologies although its effects may be systemic ( 73 , 74 ). The range and magnitude of potential impacts of 5G technologies are under-researched, although important biological outcomes have been reported with millimeter wavelength exposure. These include oxidative stress and altered gene expression, effects on skin and systemic effects such as on immune function ( 74 ). In vivo studies reporting resonance with human sweat ducts ( 73 ), acceleration of bacterial and viral replication, and other endpoints indicate the potential for novel as well as more commonly recognized biological impacts from this range of frequencies, and highlight the need for research before population-wide continuous exposures.

Gaps in Applying Current Evidence

Current exposure limits are based on an assumption that the only adverse health effect from RFR is heating from short-term (acute), time-averaged exposures ( 75 ). Unfortunately, in some countries, notably the US, scientific evidence of the potential hazards of RFR has been largely dismissed ( 76 ). Findings of carcinogenicity, infertility and cell damage occurring at daily exposure levels—within current limits—indicate that existing exposure standards are not sufficiently protective of public health. Evidence of carcinogenicity alone, such as that from the NTP study, should be sufficient to recognize that current exposure limits are inadequate.

Public health authorities in many jurisdictions have not yet incorporated the latest science from the U.S. NTP or other groups. Many cite 28-year old guidelines by the Institute of Electrical and Electronic Engineers which claimed that “Research on the effects of chronic exposure and speculations on the biological significance of non-thermal interactions have not yet resulted in any meaningful basis for alteration of the standard” ( 77 ) 2 .

Conversely, some authorities have taken specific actions to reduce exposure to their citizens ( 78 ), including testing and recalling phones that exceed current exposure limits.

While we do not know how risks to individuals from using cell phones may be offset by the benefits to public health of being able to summon timely health, fire and police emergency services, the findings reported above underscore the importance of evaluating potential adverse health effects from RFR exposure, and taking pragmatic, practical actions to minimize exposure.

We propose the following considerations to address gaps in the current body of evidence:

• As many claim that we should by now be seeing an increase in the incidence of brain tumors if RFR causes them, ignoring the increases in brain tumors summarized above, a detailed evaluation of age-specific, location-specific trends in the incidence of gliomas in many countries is warranted.
• ➢ Population-based case-control designs can be more statistically powerful to determine relationships with rare outcomes such as glioma, than cohort studies. Such studies should explore the relationship between energy absorption (SAR 3 ), duration of exposure, and adverse outcomes, especially brain cancer, cardiomyopathies and abnormal cardiac rythms, hematologic malignancies, thyroid cancer.
• ➢ Cohort studies are inefficient in the study of rare outcomes with long latencies, such as glioma, because of cost-considerations relating to the follow-up required of very large cohorts needed for the study of rare outcomes. In addition, without continual resource-consuming follow-up at frequent intervals, it is not possible to ascertain ongoing information about changing technologies, uses (e.g., phoning vs. texting or accessing the Internet) and/or exposures.
• ➢ Cross-sectional studies comparing high-, medium-, and low-exposure persons may yield hypothesis-generating information about a range of outcomes relating to memory, vision, hearing, reaction-time, pain, fertility, and sleep patterns.
• Exposure assessment is poor in this field, with very little fine-grained detail as to frequencies and modulations, doses and dose rates, and peak exposures, particularly over the long-term. Solutions such as wearable meters and phone apps have not yet been incorporated in large-scale research.
• Systematic reviews on the topic could use existing databases of research reports, such as the one created by Oceania Radiofrequency Science Advisory Association ( 79 ) or EMF Portal ( 80 ), to facilitate literature searches.
• Studies should be conducted to determine appropriate locations for installation of antennae and other broadcasting systems; these studies should include examination of biomarkers of inflammation, genotoxicity, and other health indicators in persons who live at different radiuses around these installations. This is difficult to study in the general population because many people's greatest exposure arises from their personal devices.
• Further work should be undertaken to determine the distance that wireless technology antennae should be kept away from humans to ensure acceptable levels of safety, distinguishing among a broad range of sources (e.g., from commercial transmitters to Bluetooth devices), recognizing that exposures fall with the inverse of the square of the distance (The inverse-square law specifies that intensity is inversely proportional to the square of the distance from the source of radiation). The effective radiated power from cell towers needs to be regularly measured and monitored.

Policy Recommendations Based on the Evidence to Date

At the time of writing, a total of 32 countries or governmental bodies within these countries 4 have issued policies and health recommendations concerning exposure to RFR ( 78 ). Three U.S. states have issued advisories to limit exposure to RFR ( 81 – 83 ) and the Worcester Massachusetts Public Schools ( 84 ) voted to post precautionary guidelines on Wi-Fi radiation on its website. In France, Wi-Fi has been removed from pre-schools and ordered to be shut off in elementary schools when not in use, and children aged 16 years or under are banned from bringing cell phones to school ( 85 ). Because the national test agency found 9 out of 10 phones exceeded permissible radiation limits, France is also recalling several million phones.

We therefore recommend the following:

• Governmental and institutional support of data collection and analysis to monitor potential links between RFR associated with wireless technology and cancers, sperm, the heart, the nervous system, sleep, vision and hearing, and effects on children.
• Further dissemination of information regarding potential health risk information that is in wireless devices and manuals is necessary to respect users' Right To Know . Cautionary statements and protective measures should be posted on packaging and at points of sale. Governments should follow the practice of France, Israel and Belgium and mandate labeling, as for tobacco and alcohol.
• Regulations should require that any WTD that could be used or carried directly against the skin (e.g., a cell phone) or in close proximity (e.g., a device being used on the lap of a small child) be tested appropriately as used, and that this information be prominently displayed at point of sale, on packaging, and both on the exterior and within the device.
• IARC should convene a new working group to update the categorization of RFR, including current scientific findings that highlight, in particular, risks to youngsters of subsequent cancers. We note that an IARC Advisory Group has recently recommended that RFR should be re-evaluated by the IARC Monographs program with high priority.
• The World Health Organization (WHO) should complete its long-standing RFR systematic review project, using strong modern scientific methods. National and regional public health authorities similarly need to update their understanding and to provide adequate precautionary guidance for the public to minimize potential health risks.
• Emerging human evidence is confirming animal evidence of developmental problems with RFR exposure during pregnancy. RFR sources should be avoided and distanced from expectant mothers, as recommended by physicians and scientists ( babysafeproject.org ).
• Other countries should follow France, limiting RFR exposure in children under 16 years of age.
• Cell towers should be distanced from homes, daycare centers, schools, and places frequented by pregnant women, men who wish to father healthy children, and the young.

Specific examples of how the health policy recommendations above, invoking the Precautionary Principle, might be practically applied to protect public health, are provided in the Annex .

Author Contributions

All authors listed have made a substantial, direct and intellectual contribution to the work, and approved it for publication.

Conflict of Interest Statement

The authors declare that this manuscript was drafted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest, although subsequent to its preparation, DD became a consultant to legal counsel representing persons with glioma attributed to radiation from cell phones.

Acknowledgments

The authors acknowledge the contributions of Mr. Ali Siddiqui in drafting the Policy Recommendations, and those from members of the Board of the International Network for Epidemiology in Policy (INEP) into previous iterations of this manuscript. We are grateful to external reviewers for their thoughtful critiques that have served to improve both accuracy and presentation.This manuscript was initially developed by the authors as a draft of a Position Statement of INEP. The opportunity was then provided to INEP's 23 member organizations to endorse what the INEP Board had recommended, but 12 of those member organizations elected not to vote. Of the 11 that did vote, three endorsed the statement, two voted against it, and six abstained. Ultimately, the Board voted to abandon its involvement with what it determined to be a divisive topic. The authors then decided that, in the public interest, the document should be published independent of INEP.

1 Per IEEE C95.1-1991, the radio-frequency radiation frequency range is from 3 kHz to 300 GHz and is non-ionizing.

2 The FCC adopted the IEEE C95.1 1991 standard in 1996.

3 When necessary, SAR values should be adjusted for age of child in W/kg.

4 Argentina, Australia, Austria, Belgium, Canada, Chile, Cyprus, Denmark, European Environmental Agency, European Parliament, Finland, France, French Polynesia, Germany, Greece, Italy, India, Ireland, Israel, Namibia, New Zealand, Poland, Romania, Russia, Singapore, Spain, Switzerland, Taiwan, Tanzania, Turkey, United Kingdom, United States.

Annex: Examples of Actions for Reducing RFR Exposure

• Focus actions for reducing exposure to RFR on pregnant women, infants, children and adolescents, as well as males who might wish to become fathers.
• Reduce, as much as possible, the extent to which infants and young children are exposed to RFR from Wi-Fi-enabled devices such as baby monitors, wearable devices, cell phones, tablets, etc.
• Avoid placing cell towers and small cell antennae close to schools and homes pending further research and revision of the existing exposure limits. In schools, homes and the workplace, cable or optical fiber connections to the Internet are preferred. Wi-Fi routers in schools and daycares/kindergartens should be strongly discouraged and programs instituted to provide Internet access via cable or fiber.
• Ensure that WTDs minimize radiation by transmitting only when necessary, and as infrequently as is feasible. Examples include transmitting only in response to a signal (e.g., accessing a router or querying a device, a cordless phone handset being turned on, or voice or motion activation). Prominent, visible power switches are needed to ensure that WTDs can be easily turned on only when needed, and off when not required (e.g., Wi-Fi when sleeping).
• Lower permitted power densities in close proximity to fixed-site antennae, from “occupational” limits to exposure limits for the general public.
• Update current exposure limits to be protective against the non-thermal effects of RFR. Such action should be taken by all heath ministries and public health agencies, as well as industry regulatory bodies. Exposure limits should be based on measurements of RFR levels related to biological effects ( 2 ).
• Ensure that advisories relating to cell phone use are placed in such a way that purchasers can find them easily, similar to the Berkeley Cell Phone “Right to Know” Ordinance ( 86 ).
• Advise the public that texting and speaker mode are preferable to holding cell phones to the ear. Alternatively, use hands-free accessories for cell phones, including air tube headsets that interrupt the transmission of RFR.
• When possible, keep cell phones away from the body (e.g., on a nearby desk, in a purse or bag, or on a mounted hands-free accessory in motor vehicles).
• Delay the widespread implementation of 5G (and any other new technology) until studies can be conducted to assess safety. This includes a wide range of household and community-wide infrastructure WTDs and self-driving vehicles, as well as the building of 5G minicells.
• Fiber-optic connections for the Internet should be made available to every home, office, school, warehouse and factory, when and where possible.

Safety & Prevention

Cell phone radiation & children’s health: what parents need to know.

​Children are not just little adults; their growing minds and bodies make them uniquely vulnerable to the effects of the environment around them, including cell phone radiation. Because technology is being adopted by children at younger ages than ever before, it's even more important to investigate if cell phone usage is a health hazard.

What is cell phone radiation, anyway?

There are two types of radiation: ionizing and non-ionizing. 

Ionizing radiation (e.g., x-rays, radon, sunlight) is high frequency (and high energy).

Non-ionizing is low frequency (low energy) radiation.

Cell phones have non-ionizing radiation. Your phone sends radio frequency waves from its antenna to nearby cell towers. When you make a call, text, or use data, your phone receives radio frequency waves to its antenna from cell towers.

What does the latest research say?  

Several studies have been done to find out if cell phone use can lead to cancer. These types of studies in people have not shown clear evidence of an increased cancer risk with cell phone use. While there was a slight increase in a type of brain tumor, called a glioma, in a small group of people who spent the most total time on cell phone calls in one study, other studies have not found this to be true. 

In May 2016, the US National Toxicology Program, which is part of the National Institutes of Health (NIH), released partial findings from a two-year  study  that exposed rats to the types of radio frequency radiation that cell phones give off and compared them with a non-exposed group. Some rats developed cancerous tumors after being exposed to the radiation—showing a potential connection between exposure to radiation and an increased risk of cancer.

A few words of caution about this study:

This study was only done on rats. While rats can be good test subjects for medical research, they are not the same as humans. We do not yet know if the same results would occur in people.

The rats were exposed to very large amounts of radiation—nine hours a day, seven days a week, for two years. This is far more than most people spend holding their cell phones.

More male rats developed cancerous tumors after being exposed to the radiation than female rats. Some of the rats who developed tumors lived longer than the control group rats that were not exposed to radiation.

The analysis of all of the data from this study is not yet complete.

Why is more research needed?

Parents should not panic over the latest research, but it can be used as a good reminder to limit both children's screen time  and exposure from cell phones and other devices emitting radiation from  electomagnetic fields (EMF) . Partial findings from studies like this one give scientists reason to look into the issue more. The American Academy of Pediatrics (AAP) supports more research into how cell phone exposure affects human health long term, particularly children's health.

How can we limit cell phone radiation for ourselves and our children?

The AAP reinforces its existing recommendations on limiting cell phone use for children and teenagers. The AAP also reminds parents that cell phones are not toys, and are not recommended for infants and toddlers to play with.

Cell phone safety tips for families:

Use text messaging when possible, and use cell phones in speaker mode or with the use of hands-free kits.

When talking on the cell phone, try holding it an inch or more away from your head.

Make only short or essential calls on cell phones.

Avoid carrying your phone against the body like in a pocket, sock, or bra. Cell phone manufacturers can't guarantee that the amount of radiation you're absorbing will be at a safe level.

Do not talk on the phone or text while driving . This increases the risk of automobile crashes.

Exercise caution when using a phone or texting while walking or performing other activities. “Distracted walking” injuries are also on the rise.

If you plan to watch a movie on your device, download it first, then switch to airplane mode while you watch in order to avoid unnecessary radiation exposure.

Keep an eye on your signal strength (i.e. how many bars you have). The weaker your cell signal, the harder your phone has to work and the more radiation it gives off. It's better to wait until you have a stronger signal before using your device.

Avoid making calls in cars, elevators, trains, and buses. The cell phone works harder to get a signal through metal, so the power level increases. 

Remember that cell phones are not toys or teething items. 

Are there any regulations in place to limit cell phone radiation in the United States?

The Federal Communications Commission (FCC) decides how much radiation cell phones are allowed to give off in the US. Currently, the FCC limit is at 1.6 W/Kg. The FCC, however, has not revised the standard for cell phone radiation since 1996, and a lot has changed since then.

There are now more cell phones in the United States than there are people.

The number of cell phone calls per day, the length of each call, and the amount of time people use cell phones has increased.

Cell phone and wireless technology have had huge changes over the years. For example, how many cell phone models have you had since 1996?

Another problem is that the cell phone radiation test used by the FCC is based on the devices' possible effect on large adults—not children. Children's skulls are thinner and can absorb more radiation. ​

Where the AAP stands:

The AAP supports the review of radiation standards for cell phones in an effort to protect children's health, reflect current cell phone use patterns, and provide meaningful consumer disclosure. Providing parents with information about any potential risks arms them with the information they need to make informed decisions for their families. The AAP advocates for more research into how cell phone exposure affects human health long term, particularly children’s health. ​

Additional Information & Resources:

Cell Phones: What's the Right Age to Start?

Parents of Young Children: Put Down Your Smartphones

Cell Phones (National Institute of Environmental Health Sciences)   

Cell Phones and Cancer Risk Fact Sheet (National Cancer Institute)  ​

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Volume 65, Issue 2, March 2024

Fundamental radiation science, regular papers, anti-radiation effect of mrn-100: a hydro-ferrate fluid, in vivo.

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divert power to shields —

Shields up: new ideas might make active shielding viable, active shielding was first proposed in the '60s. we’re finally close to making it work..

Jacek Krywko - Mar 11, 2024 10:00 am UTC

On October 19, 1989, at 12:29 UT, a monstrous X13 class solar flare triggered a geomagnetic storm so strong that auroras lit up the skies in Japan, America, Australia, and even Germany the following day. Had you been flying around the Moon at that time, you would have absorbed well over 6 Sieverts of radiation—a dose that would most likely kill you within a month or so.

This is why the Orion spacecraft that is supposed to take humans on a Moon fly-by mission this year has a heavily shielded storm shelter for the crew. But shelters like that aren’t sufficient for a flight to Mars—Orion’s shield is designed for a 30-day mission.

To obtain protection comparable to what we enjoy on Earth would require hundreds of tons of material, and that's simply not possible in orbit. The primary alternative—using active shields that deflect charged particles just like the Earth’s magnetic field does—was first proposed in the 1960s. Today, we’re finally close to making it work.

Deep-space radiation

Space radiation comes in two different flavors. Solar events like flares or coronal mass ejections can cause very high fluxes of charged particles (mostly protons). They're nasty when you have no shelter but are relatively easy to shield against since solar protons are mostly low energy. The majority of solar particle events flux is between 30 Mega-electronVolts to 100 MeV and could be stopped by Orion-like shelters.

Then there are galactic cosmic rays: particles coming from outside the Solar System, set in motion by faraway supernovas or neutron stars. These are relatively rare but are coming at you all the time from all directions. They also have high energies, starting at 200 MeV and going to several GeVs, which makes them extremely penetrating. Thick masses don’t provide much shielding against them. When high-energy cosmic ray particles hit thin shields, they produce many lower-energy particles—you’d be better off with no shield at all.

The particles with energies between 70 MeV and 500 MeV are responsible for 95 percent of the radiation dose that astronauts get in space. On short flights, solar storms are the main concern because they can be quite violent and do lots of damage very quickly. The longer you fly, though, GCRs become more of an issue because their dose accumulates over time, and they can go through pretty much everything we try to put in their way.

What keeps us safe at home

The reason nearly none of this radiation can reach us is that Earth has a natural, multi-stage shielding system. It begins with its magnetic field, which deflects most of the incoming particles toward the poles. A charged particle in a magnetic field follows a curve—the stronger the field, the tighter the curve. Earth’s magnetic field is very weak and barely bends incoming particles, but it is huge, extending thousands of kilometers into space.

Anything that makes it through the magnetic field runs into the atmosphere, which, when it comes to shielding, is the equivalent of an aluminum wall that's 3 meters thick. Finally, there is the planet itself, which essentially cuts the radiation in half since you always have 6.5 billion trillion tons of rock shielding you from the bottom.

To put that in perspective, the Apollo crew module had on average 5 grams of mass per square centimeter standing between the crew and radiation. A typical ISS module has twice that, about 10 g/cm2. The Orion shelter has 35–45 g/cm2, depending on where you sit exactly, and it weighs 36 tons. On Earth, the atmosphere alone gives you 810 g/cm2—roughly 20 times more than our best shielded spaceships.

The two options are to add more mass—which gets expensive quickly—or to shorten the length of the mission, which isn’t always possible. So solving radiation with passive mass won't cut it for longer missions, even using the best shielding materials like polyethylene or water. This is why making a miniaturized, portable version of the Earth’s magnetic field was on the table from the first days of space exploration. Unfortunately, we discovered it was far easier said than done.

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Channel ars technica.