|
 | ||
|
| back to electropollution | [Microwave News] September/October 2000 Leading Epidemiologists See Childhood Leukemia Risk at 4 mG A pooled analysis of raw data from nine different electromagnetic field (EMF) studies has found that children exposed to 4 mG or more were twice as likely to develop leukemia. There was no excess risk at lower exposures. "The level of [statistical] significance that we see for the excess risk at high exposure makes chance an unlikely explanation," an international team of leading epidemiologists writes in the September issue of the British Journal of Cancer (83,p.692-698, 2000). Led by Dr. Anders Ahlbom of the Karolinska Institute in Stockholm, the study team includes Drs. Nicholas Day of the U.K., Maria Feychting of Sweden, Martha Linet of the U.S., Mary McBride of Canada, Jsrg Michaelis of Germany, J¿rgen Olsen of Denmark, Tore Tynes of Norway and Pia Verkasalo of Finland, each of whom has led an important study in his or her own country. The new findings are similar to those announced last year by Dr. Sander Greenland of the University of California, Los Angeles (see MWN,S/O99), in an analysis that combined data from many of the same studies. "It's a pretty consistent picture. It's more consistent than one would have any right to expect, given the differences in how these studies were carried out," Greenland told Microwave News this September. "The main point is, you don't see anything until you get into the higher categories." Greenland's findings will be published in the November issue of Epidemiology. The Ahlbom and Greenland papers reflect a growing consensus on the apparent association between magnetic fields and childhood leukemia. But there is no consensus on what those data mean. (Story continues) ------------------------------------------------------------------------ Views on the News: What 4 Milligauss Means A consensus is emerging on EMFs and childhood leukemia that is nothing short of remarkable. Not long ago many people, including well-informed researchers, would have characterized the existing epidemiological studies as a muddle some finding a health risk, others finding nothing at all. But when the data are pulled together, a different picture emerges: a clear and consistent pattern of significant risks for average exposures above 4 mG. You wouldn't know it from the mass media, but the evidence for an association between magnetic field exposure and childhood leukemia is now stronger than ever. In particular, it is far stronger than it was in the early 1990s, when newspapers covered the story on the front page. Today there is less debate over whether there is an association and more about what it means. Even if the link is not due to bias, Dr. Martha Linet of the National Cancer Institute favors focusing research on other possible causes. "There is no risk for the 99.2% of kids with exposures under 4 mG," she argues. "There are a lot of other things we could study that would explain more than 0.8% of one type of childhood cancer." Linet is right to emphasize how little we know about children's cancer, but it is wrong to think that this makes the EMF childhood leukemia connection unimportant. First, while most children do not live in high-EMF environments, there are millions around the world who do. Second, the idea that there may be a health effect at four milligauss is a scientific bombshell, and this cannot be left unresolved. Third, public opposition to new power lines is an expensive problem for the electric utility industry and it is not going to go away. If the risk observed above 4 mG reflects a real health effect, that means that around a million children are at increased risk for leukemia in the U.S. alone (see MWN, M/J98). Over a million Americans, including hundreds of thousands of children, have average daily exposures above 10 mG. The percentage of high-exposure homes is larger in North America than in Europe, due to different ways of distributing electricity, but on every continent there are millions of workers with reason to be concerned. If a 4 mG exposure can injure human health, what does that mean for garment workers? Sewing machine operators can easily average 20 or 30 mG for eight hours a day, with their legs exposed to 200 mG or more (see MWN,S/O95). A biological effect from a 4 mG magnetic field is supposed to be impossible. The traditional view of non-ionizing radiation is that such exposure is safe as long as you don't get shocked or cooked. Once unquestioned, that paradigm is now in retreat. There is increasing agreement among biologists that nonthermal biological effects do exist, and there is evidence that some such effects may injure health. Impossible, according to the old theory but it may be happening every day. If our scientific understanding of extremely-low-frequency magnetic fields might have been so wrong, what does that mean for higher-frequency RF/MW radiation? From power lines to mobile phones to military radar, our safety standards are on shaky ground. From the IEEE to ICNIRP, it is clear they need an overhaul. It is less clear what should replace them. Until these scientific and regulatory issues are resolved, we can be sure of one thing: Public concern about EMFs is here to stay. Parents in high-exposure homes have reason to be anxious about their children's health, and the data linking EMFs and childhood leukemia are robust enough that this is not likely to change. That has important implications for the utility industry. Even with less of a media spotlight on EMFs in recent years, public concern has put a damper on new power line construction. Now rising demand for electricity has converged with deregulation and the decline of conservation measures to produce a loud industry campaign for more plants and more transmission lines. But anyone who thinks parents are about to welcome high-voltage lines into their backyards is in for a rude surprise. Suburban neighborhoods have sprawled into formerly open land, which makes it more difficult than ever to build new transmission lines without plowing through population centers. The utility industry is on a collision course with the soccer moms, and the moms are not about to get out of the way. For the sake of public health, the sake of science and the sake of economics, we need better answers about the effects of low-energy radiation. The ubiquity of technology in modern life means that we take a bath in it every day, and we're only going to be spending more time in the tub. ------------------------------------------------------------------------ Don Maisch
| |||