I’ve always heard that living under or near power lines was harmful to your health. The other day after driving by a community located next to a massive power station with so many cables running out of it that you could actually hear the hum of electricity over the traffic, I got to wondering: is there any truth to this common belief? –Carlos G., via e-mail

Two ways you can look at this. To judge solely from the amount of research, we’re facing the gravest threat to humanity since nuclear war. Over the past 30 years, scientists have published close to 25,000 articles on the health effects of nonionizing radiation (the kind emitted by power lines). We’ve had population, occupational, and laboratory studies scrutinizing everything from high-voltage transmission lines to electric blankets. When you look at the results, though, you have to wonder why the fuss. All the investigations to date have yet to produce any clear indication that low-level electromagnetic fields from power lines are a health hazard to the general public. I won’t say there’s no danger whatsoever, but the perception bears no relation to the threat.

Some background. Magnets and moving electric currents radiate energy into space, generating the invisible aura we call an electromagnetic field (EMF). The stronger the magnet or current, the more pronounced the field. These fields penetrate solid objects with relative ease and produce readily detectable effects, one of the better known of which is the broadcasting industry. Long ago some genius realized: Cheezit, if music moguls can turn teenage minds to mush using nine-volt transistor radios, what deviltry might we be unwittingly visiting on ourselves with a 128,000-volt high-tension line? Thus the busy investigative agenda adverted to above.

The first high-profile study to assert a link between power lines and cancer was a 1979 plotting of childhood leukemia rates against residential distance from power lines in Denver–the closer the cables, the higher the incidence of leukemia. This study didn’t actually measure EMF strength in the homes, nor did it control for possible confounding factors such as income levels. (Possibly housing near power lines is occupied predominantly by poor people, whose health is worse overall.) But it did prompt lots of other research, most of which uncovered nothing.

I’ll say this, though. Evidence for a link between EMF exposure and childhood leukemia turns up just often enough that it can’t be entirely dismissed. Although the vast majority of research in the U.S., Canada, and the UK has found little connection between leukemia and proximity to power lines, a large 2005 investigation received a lot of press coverage for showing a modest, if baffling, correlation. This was the so-called Draper study, an examination of most childhood leukemia cases among kids born in Britain between 1962 and 1995. Draper and his colleagues found a clear relationship between the disease and residential distance from high-voltage power lines, even after adjusting for poverty levels. However, the study showed a leukemia increase even at distances where the electromagnetic energy radiated from power lines was much less than that generated by ordinary household wiring and appliances. The researchers conceded, “We have no satisfactory explanation for our results in terms of causation by magnetic fields, and the findings are not supported by convincing laboratory data or any accepted biological mechanism.”

Some contend the increase in leukemia is related to that humming you hear from electrical lines and equipment. High-voltage power lines can ionize the air around them, an effect called corona discharge. In addition to buzzing, these discharges create pollutants such as ozone and nitrogen oxides and ionize other airborne pollutants, making them more likely to stick in your lungs when inhaled. One problem with this theory is that ozone and nitrogen oxides aren’t especially carcinogenic, and no link has been demonstrated between them and leukemia.

Another conjecture is that some people have “electromagnetic hypersensitivity,” or EHS. People claiming to suffer from EHS have a strange assortment of symptoms, including skin disorders, fatigue, difficulty concentrating, heart palpitations, and even digestive problems. However, according to the World Health Organization, EHS doesn’t stand up to double-blind testing and could be attributable to anything from poor ergonomics to stress to psychiatric conditions.

Despite the lack of evidence linking power lines to health problems, consumer advocacy groups still urge limits on exposure, and research plods along. Even if a risk is established, it may not be big enough to warrant action. As the British Medical Journal commented following the Draper study, the net negative health effect of power lines in the UK could be five cases of leukemia annually, compared to 32,000 children injured and 200 killed each year in car accidents. Most will surely concede electricity’s benefits outweigh a few additional cancer cases, provided they’re not one.

Art accompanying story in printed newspaper (not available in this archive): illustration/Slug Signorino.