What We Know—and Don’t Know—about Electromagnetic Radiation from Wi-Fi and Phones

EMR Basics

1. •EMR comes in a spectrum, from gamma rays to visible light to radio waves. Wi-Fi and cell phones use microwave radiation that falls between visible light and radio waves.
2. •Regulatory agencies and much of the scientific community agree that, based on a great deal of research, the microwave radiation used for Wi-Fi, 3G, 4G, cell phones, and microwaves is safe when used properly. But improper use that results in the heating of tissues can have adverse effects.
3. •There is controversy over the significance of nonthermal effects of EMR. Rates of childhood leukemia, brain cancer, and miscarriage have been correlated with levels of exposure to EMR in some but not all studies.
4. •The strength of EMR decreases exponentially with distance from the source. The head’s radiation exposure from a cell phone is lower when the phone is held a few centimeters away from the head than when it’s held directly against the head. EMR exposure can be measured by a portable device.
5. •Because it is difficult to estimate the amount of EMR people were exposed to during the years prior to developing a disease, data linking EMR with disease is not considered high-quality. Further, this kind of observational research does not demonstrate causation—it demonstrates associations that may turn out to be coincidental.
6. •So far, there has not been evidence of unique health effects from 5G. On the other hand, we do not yet have evidence that use of 5G as planned will be completely safe.
7. •Scientists and regulatory agencies agree that further research is required to understand how to safely use EMR in the future.

Types of EMR

EMR is not a very useful term because it’s not specific. EMR comes in a spectrum of wavelengths, with the shortest wavelengths—the high-energy gamma rays and X-rays—being the most dangerous. X-rays and gamma rays are types of ionizing radiation that damage molecules and cells. Because of this, they are used at high levels in radiation therapy to destroy tumors. However, many years later, new tumors may occur as a result of damage to DNA from the radiation therapy.

We are exposed to ionizing radiation from medical X-rays and CT scans and also from natural sources, like radon gas. Radon gas comes from certain soil types, accumulates in homes, and is a major cause of lung cancer. Largely due to increased use of CT scans, medical imaging has overtaken natural background radiation as the largest source of ionizing radiation exposure in the US.

Ultraviolet light comprises wavelengths a little longer than X-rays on the light spectrum. It is another form of ionizing radiation that is dangerous, causing sunburns and increasing risk of skin cancers.

Next on the spectrum are various forms of nonionizing radiation: visible light, infrared light, microwaves, and radio waves. Visible light, infrared light, and radio waves do not pose any known danger. Microwave radiation—the type people are concerned about—falls in between infrared light and radio waves on the spectrum. Microwave radiation includes the wavelengths used for microwave ovens, 3G, 4G, 5G, and Wi-Fi.

The first rollout of 5G uses wavelengths already in use for other wireless systems. More-powerful iterations of 5G will use subclasses of microwave radiation called centimeter and millimeter waves (MMW). In talking about the effects of EMR, it’s important to specify the type of wave and take into account the amount, or strength, of the radiation.

Courtesy of NIH/DOHS

Proper Use of EMR

Much of the scientific community agrees that, based on a great deal of research, the microwave radiation used for Wi-Fi, 3G, 4G, cell phones, and microwaves is safe when used properly, although some health professionals still question this conclusion. The potential for adverse consequences when EMR is not used properly, such as when body tissue is heated, is not disputed. Because sperm production is sensitive to temperature, the testes may be particularly affected by heating from a cell phone kept in a pants pocket. EMR from cell phones has been shown in some but not all animal studies to decrease sperm count and motility. Chronic exposure to heat from radiation can also damage the skin and eyes, so the Federal Communications Commission (FCC) has set limits for how much radiation we can be exposed to.

The scientific community is still wrestling with the issue of safe use levels for cell phone radiation. Extensive measurements from a study in France showed that most cell phones don’t meet standards for microwave radiation exposure and greatly exceed radiation exposure limits when touching the body. Cell phone manufacturers try to make up for this by recommending that cell phones be held five to twenty-five millimeters away from the head. It’s not clear whether this is a good solution, and more research is needed on this.

More Controversial Effects of EMR

The biggest controversy around EMR lies in the possibility of nonthermal effects. People have questioned whether microwave radiation from cell phones or Wi-Fi can cause breaks in DNA, leakage in the blood-brain barrier, or cancer. In human studies, a link between EMR exposure and an increased risk of miscarriage has been suggested by correlating rates of miscarriage and exposure to EMR-emitting devices such as cell phones. It is not uncommon for this sort of study to yield misleading results because it is difficult to rule out all of the other lifestyle factors that could be causing miscarriage. It’s crucial to gather more data and carry out well-controlled trials to resolve this.

EMR and Cancer

There is confusion about the strength of the evidence linking EMR and cancer. In 2011, the WHO classified EMR as a class 2B carcinogen, a classification that is widely misinterpreted. This does not mean that the WHO said that EMR causes cancer. It means that there is limited evidence in humans and none in animals and that additional research is called for. Other things characterized as class 2B carcinogens include aloe vera leaf extract, bracken fern, and goldenseal root powder. Since then, a large amount of research has been published and overall the evidence is suggestive, not definitive.

To understand why the scientific community is hesitant to accept that EMR could be carcinogenic, it helps to envision what it would take to clearly demonstrate that it causes cancer: a large-scale double-blind placebo-controlled study. People would be randomized to receive exposure to controlled amounts of EMR for many years while others would be randomized to protection from any EMR exposure during this time. These sorts of controlled clinical trials are not possible, and furthermore, they are unethical because we don’t yet know what the health effects of EMR exposure are. The next best choice is to carry out controlled experiments with animals and do observational studies, following people to see whether those with higher exposure to EMR have higher rates of cancer over time. These kinds of studies have found that if there is a true effect of EMR on cancer, it is small and difficult to measure.

Human Studies on Childhood Leukemia

In several reviews of observational studies, childhood leukemia has been linked to EMR produced by high-power electrical transmission lines. The amount of radiation exposure from power lines decreases exponentially the farther you are from the source. A very small percentage of children in the studies who lived or were born closest to transmission lines and received the highest exposure were found to have higher rates of leukemia.

Taking all of the evidence into account, in 2015, the European Commission Scientific Committee on Emerging and Newly Identified Health Risks stated that there was a correlation between high exposure to EMR and childhood leukemia. However, the commission also stated that it was not clear that EMR was causing the leukemia. The association could be due to the EMR generated by the power lines, or it could be due to other factors that the people who lived nearest power lines have in common, such as socioeconomic status. And it is very difficult to accurately determine the amount of radiation that the children were exposed to years in the past, making these finding unreliable.

Large studies carried out by the UCLA Fielding School of Public Health in 2016 and 2017 have reported that they have not found clear evidence that EMR exposure is correlated with increased risk of leukemia, but that a small level of risk is not yet ruled out.

Human Studies on Brain Cancer

In addition to leukemia, some studies have suggested that brain cancer is linked to EMR. Researchers have correlated longer-term or higher exposure to EMR from cell phones with the development of a brain cancer called glioma. This research entails asking people to recall their cell phone use—and sometimes their use of cordless phones—for many years in the past. From this type of retrospective study, it will never be clear whether the correlation is a coincidence, or whether there is direct causation. However, a strong correlation may justify additional research that can discern cause-and-effect relationships.

Keep in mind that the accuracy of human studies using self-reporting measures depends on people being able to remember how many hours they spent on the phone over the past ten years and longer. Memories may be altered by a suspicion that the phone caused their brain cancer—this is recall bias. This may be likely if someone develops a brain cancer on the side of their head that they hold their phone to. It would be natural to want an explanation for a diagnosis of brain cancer and to subconsciously overestimate cell phone use.

In 2010, authors of an international study called INTERPHONE concluded that their results did not demonstrate a link between cell phone use and brain cancer. The researchers determined whether people with brain cancer had used cell phones more than people who did not have brain cancer. People were asked to recall their cell phone usage for more than ten years. A few of the numerous statistical comparisons showed a correlation between high cell phone use and rates of cancer. On the other hand, more than forty statistical comparisons correlated cell phone use with decreased likelihood of cancer.

In 2015, scientists from Umeå University in Sweden came to a different conclusion: They reported that cell phone use was associated with increased occurrence of glioma. Their data showed a two- to threefold higher risk of glioma in people who reported the very highest or longest use of cell phones. Risk of glioma was highest on the side of the head that the phone was used on, and in the part of the brain nearest the ear (the temporal lobe). Risk was also highest in people who started using cell phones before age twenty. This study had the same limitations discussed above, including potential recall bias from relying on people remembering how often they had used cell phones in years past, and it also included a smaller number of people than the INTERPHONE study.

Largely because of the problems inherent in this type of research, there is not yet agreement on whether cell phone use has a meaningful impact on risk of brain cancer. The European Commission Scientific Committee on Emerging and Newly Identified Health Risks concluded in 2015 that there was no increased risk of brain tumors or other cancers of the head and neck in adults or children as a result of EMR exposure.

More recently, two meta-analyses published in 2017 concluded that an increased risk of glioma is not seen in people who have used cell phones for less than ten years but that studies have consistently found increased risk of glioma correlating with the use of cell phones for more than ten years. They also concluded that there was no evidence for increased risk of other types of brain tumors, such as meningioma or acoustic neuroma. However, both analyses stated that the evidence was of poor quality and recommended further research before drawing firm conclusions.

It’s important to remember that poor-quality evidence can be misleading. Here’s an example that is not related to EMR: the observational studies that were cited for many years to justify the use of estrogen and progesterone hormone replacement therapy by menopausal women. Large observational studies reported that hormone therapy was associated with better cardiovascular health. When controlled trials were done, the opposite was found to be true.

Animal Studies on Cancer

Research on EMR and cancer in animals has been inconclusive and of inconsistent quality. To address these problems, a major study from the US National Toxicology Program looked at the relationship between controlled exposure to EMR and the development of cancer in rats and mice. Rats were exposed to two types of EMR that are used in 2G and 3G wireless networks, starting in utero and continuing through their lives.

Exposure of pregnant rats to radiation did not cause miscarriage, although exposed pups weighed less than control pups. Male—but not female—rats exposed to EMR developed more gliomas and heart tumors (schwannomas) than unexposed rats. The number of tumors was low, but the results were considered significant. As with most of the research on EMR, there is a caveat: Under the best of circumstances, rats will develop gliomas, and the initial report on this research stated that the number of gliomas was not more than normally expected for this species of rat.

This study also reported something unexpected that either casts doubt on the entire experiment or raises new questions: All groups of male rats exposed to both kinds of EMR at three different levels lived significantly longer than the control rats. As with any research but especially because of the unexpected difference in life span in the animals exposed to EMR, these results require additional well-controlled research to confirm that they are not spurious.

5G Thermal Effects

So far, there has not been evidence of unique health effects from 5G, and government agencies report that moderate levels of exposure are not of concern. On the other hand, we do not yet have evidence that use of 5G will be completely safe. This type of research requires data from large numbers of people exposed to high levels of 5G.

The potential that 5G may have some adverse effects is not disputed: The FCC and the International Commission on Non-Ionizing Radiation Protection (ICNIRP) have both adopted guidelines for the amount of MMW radiation—a subclass of microwave radiation used in 5G—that people can safely be exposed to. MMW is absorbed by skin cells, heating them, and at high enough levels, it can burn skin. The ability of high levels of MMW to heat cells has potential for multiple uses. Applying microwave radiation directly to tumors in order to generate heat and to sensitize them to chemotherapy is being investigated as an adjunct cancer therapy.

The Institute of Electrical and Electronics Engineers International Committee on Electromagnetic Safety has concluded that thermal effects are the only health concerns for MMW, based on an extensive review of over 1,300 primary peer-reviewed studies. The question is: Do existing policies and regulations adequately protect us from thermal effects? 5G will allow increased use of virtual reality, autonomous vehicles, and smart cities, but we do not yet know the long-term consequences of heating the eyes and skin through cell phone and electronic use at real-life levels.

Doubts and Remaining Questions About 5G

Some scientists have proposed that MMW has harmful effects that are not related to thermal damage. For example, when skin cells were exposed to maximum allowable levels of MMW, causing their temperature to be significantly increased, they responded with many changes in gene expression. Some of these changes were not seen when the cells were heated in another way. In 2019, an extensive analysis of the published research on MMW concluded that there are not yet enough blind, well-controlled experiments that have been independently verified to know whether nonthermal damage is a real issue or not. Whether further research will confirm nonthermal effects of MMW is not yet known.

Research scientists from the NYU Department of Radiology and the NYU Polytechnic School of Engineering have clearly stated that more research on 5G radiation is called for in order to ensure its safe use: “Biological study of mm Waves is needed to ensure safety and to enhance our fundamental understanding of the interactions of mm Wave systems with the human body.… It is important to note that many governments presently rely on regulations that were developed before the year 2000, well before the rapid growth of wireless communications and low-cost mm Wave devices.”

Learning More

For those interested in learning more about existing research, the Institute of Occupational Medicine in Germany has an open-access website called EMF-Portal, which has over 21,000 scientific papers on the effects of EMF on human health and biological systems.