Electric and magnetic fields created by power transmission and distribution are not connected to causes of cancer in general or of leukæmia in children, according to the UK’s NRPB (National Radiological Protection Board); but its newly published report (ELF Electromagnetic Fields and the Risk of Cancer) was not able to rule out absolutely the possibility that intense and prolonged exposures to magnetic fields can increase the risk to children, because of a statistical link between exposure to strong electromagnetic fields in the home and childhood leukæmia. The report states that “there is no good evidence that extremely low frequency electromagnetic fields are capable of producing cancer in general.” and that “in the absence of clear evidence of carcinogenic effect in adults, or a plausible explanation from experiments on animals or isolated cells, the epidemiological evidence is … not strong enough to justify a firm conclusion that such fields cause leukemia in children”.
So evidence to date has failed to establish any causal link between electromagnetic fields and cancer; but the report indicated that in any case overhead power lines could not be the main culprit. It turns out that 80 per cent of homes with high levels of magnetic fields are not situated near power lines, but no reason is known for the high levels in such homes. The threshold for a possible link was shown to be a field of 0.4 microtesla, compared to a value of 0.04 microtesla in the majority of British and European homes.
The latest findings are based on the results of nine major studies conducted since 1994. The original researchers converted their data into common formats, allowing the data to be pooled. It is the pooled data that has formed the basis of this most extensive study to date, and led epidemiologist Sir Richard Doll’s group to its conclusions, one of which statistically links E-M fields and leukæmia. However, the link is not causal, and is so tenuous that it might be attributable to flawed research, according to Sir Richard, whose reputation was made in the sixties when he established the link between cancer and smoking. One reason is that it is very difficult to get a statistical grip on a condition that is so rare, which is why twenty years of research has produced so little in the way of definitive results.
The Electricity Association, which represents the view of the UK electricity industry, has adopted the NRPB’s position, namely that the exposure levels undergone by 99 per cent of the population are not a risk, but that there remains some uncertainty about the effect of the very high fields experienced by around 0.4 per cent of the child population the UK. But even in these cases, the evidence falls far short of establishing cause and effect. And although research is not going to come to a halt, the NRPB Board has stated that the report provides no reason for a change in exposure guidelines. Moreover, it sees no purpose in further research into childhood leukemia because that would be unable to provide any better information than already exists. The case is different when applied to occupational risk, where exposures may be as high as a few tens of microtesla. The Board considers that such studies should be supported by governmental and other funding bodies.
