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On October 31, 1996 - Halloween, a day of ghosts, goblins and the macabre - the National Academy of Sciences released the findings of its research arm, the National Research Council (NRC), from its three-year review of the scientific evidence of disease associated with exposure to residential electric and magnetic fields. This review was prompted by concerns about possible adverse health effects from proximity to electric power lines carrying high currents. The magnetic field from these power lines has been assumed to be responsible for the cancers that have been associated with proximity to such power lines, although studies have shown that such disease does not correlate as well with the measured magnetic field strength at the cancer case residences as it does with the '4wire codes" that were initially developed by Nancy Wertheimer and Ed Leeper, who published the first report of such an association in 1979.

There are two major findings of note from the study carried out under the auspices of the National Research Council. One is that the association of childhood leukemia with "wire codes" is real. What this means is that the committee carrying out research review satisfied itself that the apparent association between cases of childhood leukemia and the "wire code" category of a child's residence is a real association, not a coincidence or a statistical artifact.

Because it is real, we can expect to see it occur over and over again in future studies. Indeed, because this association is real, the assignment of a residence to one of the high-risk categories or "wire code" may properly be regarded as a risk factor for the development of childhood leukemia, although neither the committee conducting the review nor the National Research Council itself explicitly said so.

The report also concluded that it could not confirm an association between other childhood cancers, or childhood cancers in general, from either "wire codes" or magnetic field strength.

It should be pointed out, though, that as more evidence is accumulated, it may happen that the evidence for such associations will grow to the point that similar conclusions can be drawn for one or more of these associations, too. At present, however, the National Research Council believes that the scientific evidence is not strong enough to justify such a conclusion for any association except the one between childhood leukemia and wire codes. The other conclusion that was reached is the one that has drawn all the media attention and given rise to all the headlines in the popular press: that there exists no clear, convincing evidence that exposure to the electric and magnetic fields in residences at power frequencies - that is, at 50 or 60 Hz - is a threat to human health.

Why couldn't the committee performing this research review conclude that there was a real threat to human health? Because it addressed the question of cause, rather than merely risk factor. It established inordinately high criteria that had to be met in order to conclude that residential electric and magnetic fields cause disease. This included not only evidence of association from epidemiological studies, but also corroborating evidence from laboratory studies, both on whole animals and on cells and tissues. It was primarily the lack of corroborating evidence from laboratory studies that prevented the committee from concluding that exposure to residential electric and magnetic fields cause diseases such as childhood cancer.

Had the committee explicitly addressed the question of risk factors, instead of confining itself to the question of cause, it would have been forced to acknowledge that the high-risk categories of "wire codes" are indeed a risk factor for the development of childhood leukemia. This would have raised all sorts of questions in the mind of the public. For example, should all houses near electric power lines be categorized by a "wire code?" If so, who should assign the category to a house? Would a high-risk "wire code" category mean that children ought not to live in such a house, but it was safe for adults? Or should adults avoid living in such a house, too?

Neither the National Research Council nor the committee that conducted the EMF research review wanted to raise these questions. So they carefully focused the attention of the media on the conclusion that there is no conclusive evidence of a health threat from the electric and magnetic fields in residences. The media fell for it. Both Newsweek and U.S. News and World Report did report on the committee's findings, the former an accurate full-page one November 11, 1996, page 67); the latter, a brief report containing errors. Both these reports carried headlines suggesting that the fields from electric power lines have been exonerated of responsibility for the diseases that have been allegedly associated with them - a conclusion that is not warranted by either the scientific data or the totality of the conclusions from the NRC report.

Most of us are aware of the many studies of the associations of lung cancer with cigarette smoking. For decades there was a clear evidence of an association between the two, although scientific evidence that cigarette smoking caused lung cancer was lacking. The scientific evidence showed that cigarette smoking was a risk factor for the development of lung cancer, and on this basis, the federal government took regulatory action: because cigarettes themselves are legal, the Surgeon General simply required a warning on cigarette packages.

Does the finding of the NRC committee that the association between childhood leukemia and "wire codes" is real constitute a basis for regulatory action by the government? In principle, yes, though the NRC report doesn't provide a quantitative basis for regulatory action. Because the association is between disease and "wire code" category, not magnetic field strength, the appropriate entity,' to regulate is what makes up wire codes, not magnetic field strength. Wire codes are based on two factors: the distance of the residence from the power line, and the (presumed) maximum current carrying capacity of the line. So any regulation undertaken on the basis of the NRC report should address distance and/or maximum current in the power line, not magnetic field strength.

This article by Dr. Lundquist originally appeared in the Fall/Winter 1996 edition of Network News.

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