Leukemia effects confirmed
Two new studies show a clear link between low magnetic fields from power sources and childhood leukemia.
In 1979 Nancy Wertheimer released the results of a five year investigation which showed that children who lived near high-current wiring were twice as likely to develop cancer as those living near low-current wiring. This remarkable and unexpected discovery suggested, for the first time, that exposures from the power system might pose a serious public health hazard.
While Wertheimer expected that her findings would generate a will to investigate the issue, they did not. The study was at first dismissed and later condemned, while scientific bodies and utilities continued to maintain that the power system posed no risk to health.
For two decades controversy has persisted.
During this time numerous studies have produced evidence that extremely low frequencies (ELF) generated by the power system are injurious to health. Yet politicians have been loathe to so much as concede risk. In Australia the government has persistently maintained that the weight of scientific evidence is that there are no adverse health effects at exposures too low to cause significant tissue heating. Accordingly, it has implemented guidelines that allow people to be exposed to 1000 milligauss (mG) in residences and 5000 mG in industry.
However, two important new papers have been released which suggest that levels of ELF too low to cause heating are a serious risk to health and which challenge the adequacy of existing guidelines and standards worldwide.
Studies by Sander Greenland and Anders Ahlbom found that exposure to just 3-4 mG is associated with a higher risk of childhood leukemia. Both are meta-analyses - analyses of the pooled data of previous studies.
Greenland’s study reviewed 15 studies of magnetic fields or wire codes and leukemia. It found that there was little risk for exposure under 3 mG, but that risk was 1.7 times the average at exposures of 3 mG and above.
The study by Ahlbom analysed data from nine earlier studies, comprising 3 247 children with leukemia and 10 400 controls. It found that children exposed to 4 mG or more had double the usual rate of leukemia.
Together the studies provide strong and consistent evidence of an effect at very low exposures. However, is the evidence strong enough to constitute proof? In an interview with Microwave News, Ahlbom stated, “if we had supporting experimental data, the epidemiology would have been strong enough for a causal interpretation quite some time ago.” (MWN Sept/Oct 2000).
The results of the two studies reinforce what has long been observed in the community - namely, that some people are developing health problems when exposed to the higher fields encountered in everyday life.
If, as indicated by these studies, exposures of 4 mG and over constitute a significant health risk, the implications are enormous. Not only are existing guidelines and standards shown to be inadequate, but so is the very rationale for their creation. The new data puts Australia’s limit for public exposure at 250 times the indicated danger levels and its industrial exposure limit at 1250 times this level.
EMRAA News Dec 2000, Vol 5 No 4