Extremely Low Frequency Electric and Magnetic Fields:
The Phantom Menace
An Editorial by Douglas Taylor, publisher of Environmental Review :
The May/June issue of Sierra magazine, published by the Sierra Club, had an article titled Current Risks, under the headline “Experts finally link electromagnetic fields and cancer.” The Sierra article is ostensibly about the recent study by the National Institute of Environmental Health and Safety which in fact did not report a link between cancer and low frequency electromagnetic fields (EMFs).
How could Sierra take a carefully worded scientific report and turn its results upside down? It turns out there is a long history of confusion about possible health effects of EMFs and the media has not done a good job of reporting the topic.
In the 1970s and 80s Paul Brodeur published a series of articles in The New Yorker magazine claiming that the dangers to peoples’ health of extremely low frequency magnetic and electric fields such as those found near electrical appliances and power lines, were being hidden. This claim is difficult to reconcile with the millions of dollars being spent on research of this issue by numerous public and private agencies including the US Department of Health and Human Services, the US Department of Labor, the US EPA, the American National Standards Institute, the World Health Organization, and the National Academy of Sciences, to name only a few.
However, publicity surrounding Brodeur’s articles and books produced support for more research on the possible health effects of EMFs. So in the late 1980s and early 1990s, a second wave of scientific reviews was funded, and have been coming out at intervals. They have all reached the same conclusion about the health effects of EMFs: not guilty, as far as we can tell. Not surprisingly these findings of no result received little attention by the major media.
What Are EMFs?
We live our lives immersed in low frequency electric and magnetic fields. An example of natural EMFs is the Earth’s magnetic field, which is what we detect when we use a compass, while an example of manmade EMFs are those very much smaller fields around electrical appliances and wires.
The static background from the Earth’s electric field is about 120 volts/meter, about the same as the field found near a kitchen appliance. Electric fields are attenuated by the human body by a factor of about 100 million. That means the electric field that a cell in our body experiences from an unshielded hotplate is tiny compared to the Earth’s static field.
Magnetic fields are a different story. Because our bodies contain almost no magnetic material, magnetic fields penetrate the human body without attenuation, and can generate electric fields in our bodies by the Faraday effect. Electric fields are also generated within our cells by the motion of ions (charged atoms and molecules); these naturally occurring fields are called thermally induced fields. Magnetically induced electric fields our bodies experience from power lines or household appliances are also small compared to thermally induced fields. However, small doses of EMFs does not necessarily mean they are harmless, for we know that many chemicals are toxic in small doses.
In the 1950s concern over the hazards of high frequency EMFs stemmed from soldiers and sailors having to work near radar and other transmitters aboard warships and aircraft; and standards for acceptable exposure to high frequency EMFs were worked out. In the 1970s and 80s epidemiology studies of the possible health effects of extremely low frequency EMFs were conducted by numerous public and private agencies, and the scientific consensus gradually emerged that there is no obvious health effect due to extremely low frequency EMFs. Higher frequency EMFs such as those used in military or medical technology are not under consideration here. In this article I refer to extremely low frequency electric and magnetic fields generated by electrical power lines simply as EMFs.
In the late 1980s further epidemiological studies suggested a possible link between EMFs and some kinds of cancer. Epidemiology works by looking at large populations to see if people with exposure to some toxin, cigarette smoke for example, have higher than average incidence of disease. Epidemiologists are the first to admit that their science is a blunt tool. Epidemiology looks for correlations between exposure and disease, but it does not provide information about cause and effect. The health effects of cigarette smoking are a classic example of epidemiology at its best. Epidemiolgy works well in that case because smoking is so unhealthy that its effects on people are hard to miss: higher rates of many kinds of cancer, heart disease, stroke, susceptibility to infectious diseases and so on. When the toxin to which people are exposed is very dangerous, like cigarette smoke, the epidemiology is consistent from one study to the next. However when epidemiology is used to look for more subtle health effects the results can be inconsistent and confusing. The major media regularly report that scientists have found that some common food like chocolate or coffee or butter is bad for you. A few months later another study comes along finding the opposite result. This scare of the month syndrome is explained by the fact that most reporters and editors don’t understand the limits of epidemiology, and by the fact that the industry has its own ideas about what is newsworthy.
This Sierra article is another example in the long running misunderstanding of the EMF issue which would be comic if it hadn’t cost so many tax dollars and hadn’t caused unnecessary grief and anxiety. In cases where health effects are not obvious, epidemiology is working at the limit of its resolution. Even so, if epidemiology studies keep seeing the same small effect over and over, then scientists will start believing there is a real effect there. This appears to be the case with red wine: there seems to be a small health benefit associated with moderate drinking of red wine. We don’t know why this is so, but the results keep coming back with the same answer so there is probably something to it.
The limitations of epidemiology is an important issue because the only evidence for adverse health effects of EMFs are epidemiological studies. These studies have found small correlations and have been inconsistent. Sometimes they see a correlation between EMFs and one or another kind of cancer, and sometimes they don’t. This inconsistency should suggest caution on the part of those who claim EMFs are dangerous. There is just as much epidemiology suggesting no effect or positive effect of EMFs as there is of bad effects; and the information is equally suspect in both directions. There are other ways of thinking about and investigating possible health effects of EMFs and they have not yet indicated that EMFs are dangerous. The use of electricity in the U.S. has increased enormously in the last one hundred years, with no apparent ill health effects: a natural experiment which appears to have a nil result. Moreover there is no known mechanism by which EMFs might cause disease. (This argument is hardly persuasive since we don’t know how cancers get started anyway.) Finally, EMFs are so small as to be dwarfed by the background of EMFs from natural sources. Taken together, the evidence for adverse health effects of EMFs is shaky to non existent.
The following paragraphs are from the executive summary of the DOE 1992 report.
“This review indicates that there is no convincing evidence in the published literature to support the contention that exposures to extremely low-frequency electric and magnetic fields generated by sources such as household appliances, video display terminals, and local power lines are demonstrable health hazards.”
“Epidemiologic findings of an association between electric and magnetic fields and childhood leukemia or other childhood or adult cancers are inconsistent and inconclusive. No plausible biological mechanism is presented that would explain causality. Neither is there conclusive evidence that these fields initiate cancer, promote cancer, or influence tumor progression. Likewise, there is no convincing evidence to support suggestions that electric and magnetic fields result in birth defects or other reproductive problems.”
The report on health effects of EMFs that caught Sierra's attention was recently published by the National Institute of Environmental Health Sciences. It covered the same ground as the previous reports and reached the same conclusions: not guilty as far as we can tell. The following is from the NIEHS report executive summary: “The scientific evidence suggesting that ELF-EMF exposures pose any health risk is weak.”
Scientists always hedge and never make absolute statements. Our conclusions are always provisional and subject to revision if new information becomes available. Therefore the more precise characterization of the EMF reports would be: not guilty as far as we can tell; we may have missed some health effect of EMFs but if we missed it, it is because it is a small one.
Reading the Sierra article mentioned above the unsuspecting reader would never guess that the NIEHS report reaches the same conclusions as the DOE report quoted above and all the others. The Sierra misrepresents the findings of the NIEHS report. It uses quotations taken out of context, a favorite rhetorical device of anti- environmentalists, to give the impression that the report has uncovered a threat to public health from EMFs when it has not.
This unfortunate article reduces the hard won credibility of the Sierra Club, its prestige, and its reputation for integrity. The anti-environmental propaganda from the radical right can be amusing in a perverse way. Much of its appeal can be likened to the thrill children get from using bad words. One can easily imagine anti- environmentalists saying, If the Sierra Club can’t get its facts straight on EMFs, why should we believe them about anything else? Perhaps the only benefit of advertising is that the American public is trained from an early age to detect and filter out propaganda. Environmental activists and educators must resist the temptation to exaggerate if they want to get people's attention and trust. We must use reason and example and trustworthy information to persuade people to take environmental issues seriously.
I urge you to join the Sierra Club, send them a donation, subscribe to the magazine and thank them for their magnificent conservation work. Having done so you will then be justified in asking the editors to cease and desist trying to scare the bejabbers out of us about EMFs. I would also suggest they organize a panel of scientists to review future articles that deal with technical matters such as EMFs or epidemiology.
Their email address is email@example.com. Their mailing address is 85 Second St, second floor, San Francisco, CA. 94105-3441. Their phone number is 415 977 5500.