This whole saga began when two Denver researchers, puzzled by small clusters of cancer in children, came to believe that living in close proximity to high-voltage power lines was a cause of leukemia.4 The analysis they published in 1979 was crude and relied on distances from homes to power lines and on wiring configurations rather than on direct measures of exposure to electromagnetic fields. They found that the risk of childhood leukemia was more than doubled among children living near such power lines, a finding that led to more studies and more concern. Soon activists and the media began to spread the word that electromagnetic fields cause cancer.
The hypothesized cause was exposure to extremely-low-frequency magnetic fields generated by the electrical current in power lines. Physicists understand these invisible fields well, but most physicians, parents, and patients do not. The movement of any electrical charge creates a magnetic field that can be measured.5 Even the 60-Hz residential electric current (50 Hz in Europe) creates a very weak oscillating field, which, like all magnetic fields, penetrates living tissue. These low-frequency electromagnetic fields are known as nonionizing radiation, since the amount of energy in them is far below that required to break molecular bonds such as those in DNA.
One ironic fact about low-frequency electromagnetic fields is that we live and worry about them within the Earth’s static magnetic field of 50 μT, which is hundreds of times greater than the oscillating magnetic field produced by 110/220-V current in houses (0.01 to 0.05 μT).5,6 Even directly under high-voltage transmission lines, the magnetic field is only about 3 to 10 μT, which is less than that in an electric railway car and much weaker than the magnetic field close to my head when I use an electric razor (about 60 μT).
Although most physicists find it inconceivable that power-line electromagnetic fields could pose a hazard to health, dozens of epidemiologic studies have reported weak positive associations between proximity to high-voltage power lines and the risk of cancer.6,7 The negative or equivocal studies did not end the controversy. Fear of leukemia is a powerful force, and the media response amplified the perception of electromagnetic fields as a health hazard. In 1989 The New Yorker published three articles by journalist Paul Brodeur that described in mesmerizing detail how maverick researchers had discovered a cause of cancer that the establishment refused to accept.8-10 Like many of the epidemiologic studies themselves, these widely quoted articles described biologic mechanisms of action for electromagnetic fields that were hypothetical, even fanciful.
Peru, Lima, City,
San Marino, San Marino,
Burkina Faso, Ouagadougou,
Green Bay Wisconsin USA
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