The preponderance of evidence suggests that the low-power, low-frequency, electromagnetic radiation associated with household current does not constitute a short or long term health hazard, and whilst some biophysical mechanisms for the promotion of cancer have been proposed (such as the electric fields around power lines attracting aerosol pollutants), none have been substantiated. Nevertheless, some research has implicated exposure in a number of adverse health effects.
These include, but are not limited to, childhood leukemia, neurodegenerative diseases (such as amyotrophic lateral sclerosis), miscarriage, and clinical depression.
One response to the potential dangers of overhead power lines is to place them underground. The earth and enclosures surrounding underground cables prevent the electric field from radiating significantly beyond the power lines, and greatly reduce the magnetic field strength radiating from the power lines, into the surrounding area. However, the cost of burying and maintaining cables at transmission voltages is several times greater than overhead power lines.
Leukemia and cancer
Suggesting no significant link
In 1997 the National Cancer Institute (NCI) released a report published in the New England Journal of Medicine, the result of a seven-year epidemiological investigation.
The study investigated 638 children with acute lymphoblastic leukemia (ALL) and 620 controls and concluded that their study provided "little evidence that living in homes characterized by high measured time-weighted average magnetic-field levels or by the highest wire-code category increases the risk of ALL in children."
Following the report, the US Department of Energy disbanded the EMF Research and Public Information Dissemination (RAPID) Program, saying that its services were no longer needed.
In 2005 the Canadian government said, "The outcome of a recently conducted pooled analysis of several epidemiological studies shows a two-fold increase in the risk of leukemia in children living in homes, where the average magnetic field levels are greater than 0.4 microtesla (4 milligauss). it is the opinion of [this committee that the epidemiological evidence to date is not strong enough to justify a conclusion that EMFs in Canadian homes, regardless of locations from power lines, cause leukemia in children."
The World Health Organization issued a fact sheet, No. 322, in June, 2007 based on the findings of a WHO work group (2007), the IARC (2002) and the ICNIRP (2003), which reviewed research conducted since the earlier publication.
The fact sheet says "that there are no substantive health issues related to ELF electric fields at levels generally encountered by members of the public." For ELF magnetic fields, the fact sheet says, "the evidence related to childhood leukaemia is not strong enough to be considered causal", and "regards other childhood cancers, cancers in adults, ... The WHO Task Group concluded that scientific evidence supporting an association between ELF magnetic field exposure and all of these health effects is much weaker than for childhood leukaemia. In some instances (i.e., for ... breast cancer) the evidence suggests that these fields do not cause them."
In 2010, Maslanyj ''et al.'', applying the Bradford-Hill criteria to available evidence, considered the application of low-cost exposure reduction measures as appropriate precautionary responses to "small and uncertain public health risks". Even after pooling all the data, they found it fell short of establishing "strength of association, dose-response relationship, biological plausibility and coherence, and analogy". They recognised that controversy would continue so long as other interpretations of the data were possible.
Suggesting a significant link
In 2001, Ahlbom ''et al.'' conducted a review into EMFs and Health, and found that there was a doubling in childhood leukemia for magnetic fields of over 0.4 µT, but said that "This is difficult to interpret in the absence of a known mechanism or reproducible experimental support".
In 2002 a study by Michelozzi ''et al.'' found a relationship between leukemia and proximity to the Vatican Radio station transmitters.
In 2005 Draper ''et al.'' found a 70% increase in childhood leukemia for those living within of an overhead transmission line, and a 23% increase for those living between . Both of these results were statistically significant. The authors considered it unlikely that the increase from 200 m to 600 m is related to magnetic fields as they are well below 0.4 µT at this distance. Bristol University (UK) has published work on a theory that could account for this increase, and would also provide a potential mechanism, being that the electric fields around power lines attract aerosol pollutants.
In 2007, the UK Health Protection Agency produced a paper showing that 43% of homes with magnetic fields of over 0.4 µT are associated with overground or underground circuits of 132 kV and above.
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