I am a scientist in the field of evidence-based medicine and public health. Basically, I am a science translator and communicator. I help healthcare workers use current science when treating patients, and developing policies and programs. Much of what I do involves working with world experts on a wide variety of topics to determine answers to health-related science issues. We ask questions about effectiveness of medical treatments. Which treatment is better? What treatments might cause harms? What are the risk factors for disease? We analyze results of clinical studies to figure out exactly what the results mean, and what we should do with this information.
In addition to my career, I live the typical life of a working mother. I have two kids (a girl and a boy), a three-bedroom house in the suburbs, a two-car garage, a cat, a dog, two fish, and an amazing husband. Rarely does my profession and personal life interact, but a few years ago on my daughter’s first day of school in first grade my worlds collided. One day while the children were having fun on the playground after school, one of the other mothers threw me what I call a panic science bomb. It seems that her daughter has eye twitches, and she has concluded that they are caused by electromagnetic fields (EMF) emanating from a transformer outside of her daughter’s classroom. The transformer also happens to be in front of my daughter’s new classroom, so that got my attention. Oh, and EMF causes cancer in children, she continued, suggesting that our daughters’ lives are at stake!
I call this a panic bomb because, although I am a scientist, I knew little about the health effects of EMFs, so for a moment I began to panic! What exactly are EMFs? And what might they be doing to my daughter and the other children at the school? My heart started racing. This is, of course, a natural reaction, for as Dr. Daniel Kahneman describes in his book Thinking Fast and Slow,1 people tend to react first with rapid intuition and emotion. But after a few moments my more thoughtful and critical thinking kicked in. I asked the mother what her daughter’s pediatrician or eye doctor had said about the eye twitches. Her response was completely unexpected. She had not taken her daughter to either a pediatrician or eye doctor. Presumably her medical information came from the Interweb. She said she has a very high standard of health for her family and was demanding that the school move the transformer.
That night, after my kids went to sleep, I spent hours online: PubMed, WHO, NIH, American Academy of Pediatrics, OSHA, Mayo Clinic. All of these organizations unequivocally stated that EMF is not associated with any health issue in adults, and there was certainly no evidence that it is associated with eye twitches. A 2002 report from the National Institute of Environmental Health Sciences, a branch of the National Institutes of Health, titled “EMF: Electric and Magnetic Fields Associated with the Use of Electric Power”, suggests that there may be a weak association between EMF and childhood leukemia.2 To those who do not have training in epidemiology and evidence-based medicine, this may sound alarming. But with a strong scientific background, I understood that association does not necessarily mean causality. The NIH document describes that the first report of an association between EMF and childhood leukemia was published in 1979,3 but that more recent, large scale studies did not find an association. I also came across a systematic review, which compiled the results of seven studies with more than 23,000 subjects, which concluded that “the association [between EMF and childhood leukemia] is weaker in the most recently conducted studies, but these studies are small and lack methodological improvements needed to resolve the apparent association.”4
At first glance, this systematic review seems to indicate that there might be a risk. But as a scientist, I do not rely solely on the authors’ conclusions of any study. I also look at the data, which in this case was presented as odds ratios,5 which is a measure of the strength of any association. A few things need to be known in order to correctly interpret odds ratios. The null value for an odds ratio, or number at which there is no difference between the exposed and unexposed groups, is 1. So any odds ratio greater than 1 represents an association. It is generally well known in the evidence-based medicine community that odds ratios between 1 and 3, especially for rare outcomes (like childhood leukemia), are not clinically significant. An assessment of statistical significances for an odds ratio is whether or not the 95% confidence interval crosses the null, in other words the entire interval must be greater than 1 in order for the results to be statistically significant. So, if there were an association between EMF and childhood leukemia, I would expect to see odds ratios greater than 3 (clinically significant) with corresponding confidence intervals all greater than 1 (statistically significant). But this is not what I found in the data! The odds ratio ranged from 1.07 to 1.44, with confidence intervals ranging from less than 1 to greater than 1. So the results of this systematic review were neither clinically significant nor statistically significant, and in the discussion section of the paper the authors noted “our results are compatible with no effect.”
Collectively, the evidence on EMF does not meet the well-established Bradford-Hill criteria used to determine causality—whether or not the exposure in question actually causes a disease.6 There is no known biological mechanism for non-ionizing EMFs (i.e. power lines, cellphones, and wifi) to cause DNA damage, and thus cancer. Both the WHO and NIH state that any risks from EMF, if they exist at all, are extremely small. The most these organizations suggest is possibly using “no or low-cost” interventions to reduce exposure, for example not standing in front of a running microwave or fridge for long periods of time. They specifically advise to not move electrical wires, much less a transformer, because the known risks of electrical work—electrocution—greatly exceeds any potentially low risk of EMF exposure.
Despite this information, evidence in support of the parents’ fears continued to be presented to the community, including a World Health Organization report on EMF hypersensitivity.7 Ironically, the WHO report includes the following conclusions about EMF Hypersensitivity: large well controlled and conducted double-blind studies have shown that symptoms do not seem to be correlated with EMF exposure; these symptoms may be due to pre-existing psychiatric conditions as well as stress reactions as a result of worrying about believed EMF health effects, rather than the EMF exposure itself; and there is no scientific basis to link symptoms to EMF exposure. Recommendations for medical care of those claiming to be hypersensitive to EMF include a medical evaluation to identify undiagnosed conditions, assessment of home and workplace for other factors that might contribute to the symptoms, and assessment of psychiatric and psychological conditions that may be responsible for the symptoms.
Sharing all of the information that I had gathered with the community did relieve the fears of many, but not everyone. I was invited by the Board of Education to give a presentation at the school about EMFs and health concerns. Many parents were thankful. Some expressed shame at their own actions in falling for the panic science bomb before gathering more information. Other parents who understood and supported the science still indicated that I had a lot of guts to speak out, because there would be repercussions in the small town where we reside. They were right. Some parents, if they looked at me at all, shot me dirty looks, even refusing to let their children play with mine. This small cohort of parents continued to be alarmed, wanting absolute proof that there is no risk. As a scientist, we know that it is impossible to prove a negative, so the standards set by the parents would never be achievable.
The topic continued to be a significant part of Board of Education meetings for almost a year, where concerned parents voiced their panic over EMFs. It got ugly. People were yelling, calling each other names. Parents were crying in desperation, fearful that their children were at great risk while the school was doing nothing!
I sincerely could not understand why these parents were not relieved to learn that there was essentially no threat. What were they so scared of, and what was I missing? For awhile I began to question my own trust in science. Were they right, and could I be wrong? I understood that if I was wrong this could impact my daughter and the other children at the school. The stakes were high! So I went a bit overboard, sharing the evidence with every epidemiologist and statistician I encountered, not giving my opinion but rather waiting to see what their independent conclusion might be. I used my connections to speak with people at the CDC and public health researchers on this topic. And it turned out that I was wrong. I was wrong in questioning the science. Any concern about EMF was based on problematic study design, misunderstanding, randomly skewed results, and fear mongering. The risks were negligible, if they exist at all, and my message to parents should have been much stronger.
In the years since this event occurred, a pivotal case control study of over 53,000 cases of children with cancer from 1962–2008 was published in the British Journal of Cancer, which unequivocally conclude that EMF is not associated with cancer.8 Ironically, this study was published by the same group that had previously published results indicating that there was an association,9 but in this more recent study they concluded about cancer that “A risk declining over time is unlikely to arise from any physical effect of the powerlines and is more likely to be the result of changing population characteristics among those living near powerlines.” It turns out that there is an overall decline in risk documented in the larger body of evidence on EMF, and because of this many of the scientists who had originally raised the red flag on EMF have changed their opinion.10 In fact, David Savitz, an epidemiologist from Brown University who published one of the first rigorous studies demonstrating an association between EMF and cancer in children in 1988, now states “The likely impact of electromagnetic fields, if I had to pick a single number that is the most likely, it would be zero.”11
So how can science, and the opinion of scientists, change over time? This may be explained by the concept of regression to the mean12–14. When an extreme result is randomly derived from a study, subsequent studies have less extreme results, so over time the cumulative results tend to approach the mean. There are many examples of this in science, and this is another reason why the scientific method, including and especially repeating experiments, is so important, and also why it is critical to look at the whole body of research on a topic, not just those studies that confirm your pre-existing beliefs. The hallmark of critical thinking is being willing to change your opinion when faced with robust evidence, as was the case with these early EMF investigators.
The outcome of this story: My daughter’s classroom was moved by Halloween, and over the holiday break the transformer was moved. But not because of concerns about EMF. Rather, because of “small traces of polychlorinated biphenyl (PCB)” detected in the transformer that was previously noted to be “PCB free.”15
Since then, the dust has settled, and people talk little about the issue. But it turns out that my community was not unique in their fears of EMF. This situation has happened elsewhere and has been studied.16 Investigators have documented that the following circumstances can raise alarm regarding EMF or other perceived hazards:
Being unfamiliar with the nature of a perceived risk, and underlying sources of exposure.
Perceived lack of control about the exposure.
Perceived lack of personal benefit that compensates for the exposure.
Dreaded possible health effects.
Inadequate, conflicting, or incomplete information about scientific studies.
Lack of access to easily understood scientific information.
Media skewed to report the suspected health concern and ignore the studies that report no health effect.
Lack of a process for a fair hearing of all viewpoints within a community.
Throughout this journey, I realized that as scientists we deal with uncertainty all the time. We deal with statistics, p-values, risk ratios, odds ratios, and relative risks. This is part of our everyday vocabulary. But the general public does not think in this way. And to most parents the only acceptable risk is no risk. Science can say that the risks are likely to be very, very small, or likely nonexistent, but it cannot say with absolutely certainty that there are no risks. Scientists live in a world of statistics, probabilities, and likelihoods, but most people in the general public want absolutes.
I also realized that I had the privilege of having a level of comfort and reassurance that no other mother or father at the school had. Science was my comfort. It was then that I realized that science is not just what I do, it is who I am at heart. I see science all around me (in a glass of beer or wine, in the weather, in the process of cooking food). And I use science every day for my work and for my family (should we eat organic food? Should I be scared of GMOs? Should we get the flu vaccine?). Science is everywhere, and it is comforting and beautiful.
I also realized the importance of science communication. Everyone is a consumer of science, and needs to make decisions based on science. But as scientists we have not done the best job of making science accessible and clearly understood. We need to take the time to understand not only what people know and believe, but also why they perceive things as they do. We need to develop strategies for more effective communications so that the public can have the same comfort in and reliance on science as we do.
I also came away from the experience realizing that I need to make sure my children are critical thinkers so as adults they will make sound, rational decisions, and I have spent every day since helping to foster this. One Halloween my children asked me “Are ghosts real?” My response: “Well, what do you think?” My daughter’s reply: “All my friends say that they are real, but it doesn’t make sense. Where would they be, and what would they do? How could they exist? I do not think that ghosts are real.” With a proud smile on my face I said “You are correct. Ghosts are not real.” I took great pride in realizing that I am raising critical thinkers. My children may not choose science for their careers, but they will be critical thinkers at heart…as I am.
Addendum: Do Cell Phones Cause Cancer?
Since submitting this article to Skeptic, news reports of a study linking cell phones and cancer in rats have been published.17–19 These articles were based on a draft report of partial findings, which have not yet undergone peer review, based on an evaluation of 9 hours a day of total radiofrequency (RF) radiation to the whole body of rats, starting in utero, and found a statistically significant (1 or 2 cases) increased rate of brain gliomas and heart schwannomas in male rats only.20, 21
Click image to enlarge
Although several forms of non-ionizing radiation are frequently referred to as Electromagnetic fields (EMF), there are actually 3 different types of EMF, characterized by different frequencies. EMF produced by electrical systems, such appliances and powerlines, are known as extremely low frequency (ELF) fields (frequencies up to 300 Hz).22–24 This is the type of EMF that was of concern at the school in my article. Other types of EMF have higher frequencies: intermediate frequency (IF), sometimes referred to as very low frequency (VLF) fields (300 Hz to 10 MHz), and radio frequency (RF) fields (10 MHz to 300 GHz).22–24 Radio, television, radar, and cellular phones are the main sources of radio frequency (RF) fields. Thus, the reports of a possible link between radio frequency (RF) fields and cancer in rats is very distinct from the extremely low frequency (ELF) electromagnetic fields (EMF) discussed in my article.
Nevertheless, for those seeking information about cancer risks from cell phone use, the National Cancer Institute (NCI) has very useful and comprehensive information about the overall current state of the science.25 The NCI states that “A limited number of studies have shown some evidence of statistical association of cell phone use and brain tumor risks, but most studies have found no association” and goes on to lists possible reasons for the discrepancies, including recall bias, participant bias, and inaccurate reporting. Furthermore, the NCI lists several organizations that have released statements to the effect that current evidence does not demonstrate a causal relationship between radio frequency (RF) fields from cell phones and cancer, including the National Institute of Environmental Health and Sciences (an institute of the NIH), the US Food and Drug Administration, the US Centers for Disease Control and Prevention, and the Federal Communications Commission. Of note, however, the NCI does state that the preliminary results from the rat study “are being reviewed by NCI experts.” Furthermore, only preliminary and non-peer reviewed data about the rat study has been released thus far, with the full report anticipated to be released in fall 2017. Caution about drawing conclusions until experts are able to fully appraise all of the data from the rat study—after peer review—is warranted.
About the Author
Dr. Julie Frantsve-Hawley is the Editor-in-Chief of the International Journal of Evidence-Based Practice for Dental Hygienists, and editor of the textbook Evidence-Based Dentistry for the Dental Hygienist, and is currently Executive Director of the American Association of Public Health Dentistry. She was the senior director of the American Dental Association’s Center for Evidence-based Dentistry for 10 years, and has been a research investigator on several grants from the National Institute for Dental and Craniofacial Research, the National Library of Medicine, and the Agency for Healthcare Research and Quality. She is involved in dissemination and implementation research projects aimed at helping clinicians implement science into practice, is a member of the National Dental Practice-Based Research Network and is the secretary for the Evidence-Based Dentistry Network of the American Association for Dental Research. Dr. Hawley’s interests are in the area of science communication and the understanding and use of science by healthcare workers, policy makers, and the public. Dr. Hawley received her Ph.D. in Biomedical Sciences from Harvard University.
References
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