Environmental Assis for Orono Substation Expansion

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The study of cancer in relation to ELF magnetic fields has been a topic of study since the late 1970s. Since that time there have been several epidemiological studies that have explored the possible association of not only cancer risks, including brain tumors, leukemia, and breast cancer, but other potential human maladies including mental health issues. Studies have focused on both occupational exposures for individuals working in electrical industries and public exposures for children and adults living and working around common magnetic field sources (in-home wiring, transmission lines, home and office appliances/equipment). The results of the various studies conducted over the last three decades, specifically those regarding the relationship between EMF and childhood leukemia and other cancer risks, have been mixed; some have found an association while others have not (National Cancer Institute, 2005). Where there is association suggested in epidemiological studies, it is usually very near the statistical threshold of significance. However, when these studies are repeated in a laboratory, the results have not reproduced or identified a biological mechanism to support a link between health impacts and magnetic fields. Researchers continue to look at magnetic fields until more certain conclusions can be reached. In a 2007 report the World Health Organization (WHO) concluded that, although some studies have noted a weak statistical link between exposure to EMF and incidence of childhood leukemia, laboratory evidence does not support these findings and that a similar link has not been noted with other types of cancer: epidemiological evidence is weakened by methodological problems, such as potential selection bias. In addition, there are no accepted biophysical mechanisms that would suggest that lose -level exposures are involved in cancer development. ... Additionally, animal studies have been largely negative. Thus, on balance, the evidence related to childhood leukaemia is not strong enough to be considered causal. ... Re arding long-term effects, given the weakness of the evidence for a link between exposure to ELF extremely low frequency] magnetic fields and childhood leukaemia, the benefits of exposure reduction on health are unclear. (WHO, 2007) Although scientists are still debating whether EMF is a hazard to health, at the current time in the United States, there are no federal standards for occupational or residential exposure to magnetic fields. Florida, New York, and Massachusetts are the only three states in the country that have set standards for magnetic field exposure (Table 10). These standards were not in response to health - based analysis, but rather on maintaining transmission systems within historic levels. The International Commission on Non -Ionizing Radiation Protection (ICNIRP) has developed occupational and residential guidelines for EMF exposure (Table 11). The exposure guidelines established by the ICNIRP have typically been the guidelines adopted by most countries and organizations. They have also concluded that available data regarding potential long-term effects, such as increased risk of cancer, is insufficient to provide a basis for setting exposure restrictions. Xcel Energy prepared estimates of magnetic fields for the structure type and voltage at both average and peak system conditions have been calculated at various distances from the centerline, as presented in Table 14. Environmental Assessment PUC Docket E002/TL-11-223 Page 35