Power line consultant’s report released

Feb 9, 2018 by

Published in the February 9, 2018 edition.


WAKEFIELD — The final, written report of the independent consultant hired by the town to evaluate the health and safety issues associated with the 345kV Woburn to Wakefield underground power transmission line has been released. Dr. Robert Kavet, of Kavet Consulting in Oakland, Calif. was retained by the town in December to evaluate the possible health and safety effects of electromagnetic field (EMF) exposure along the Wakefield portion of the route.

The 3.5-mile Wakefield portion is part of a proposed 8.5-mile National Grid/Eversource underground transmission line that would run from Woburn through Winchester and Stoneham before entering Wakefield. The proposed route of the project through Wakefield would come down Albion Street and Broadway, cross North Avenue and then follow the abandoned railroad bed for approximately one mile, running across Bennett Street, Richardson Street and Water Street. The line would then turn down Salem Street to Montrose Avenue and up the access road to the National Grid Substation.

Kavet was hired in the wake of a contentious public hearing in December, when many residents expressed concern over the possible adverse health effects of EMF exposure from the line, citing epidemiology studies showing an association between living near transmission lines and diseases like childhood leukemia.

Dr. Kavet has been involved with researching EMF health and safety issues since 1978. He was closely involved in studies that included epidemiology, exposure assessment and laboratory studies covering cancer and pregnancy risks. He currently serves as co-chair of the Institute for Electrical and Electronic Engineers’ subcommittee on electromagnetic safety concerned with establishing exposure standards. He has authored or co-authored about 100 peer-reviewed publications on EMF topics.

He holds masters degrees in electrical engineering (Cornell University) and environmental health sciences (Harvard School of Public Health) and a doctoral degree in respiratory physiology from Harvard School of Public Health. He is currently affiliated with the Harvard T.H. Chan School of Public Health as an instructor.

The state Energy Facilities siting Board (EFSB) was originally expected to decide last December whether it would approve the Woburn to Wakefield project, but local officials are now hearing that a decision may come next week.

Kavet reviewed documents filed with the EFSB related to the proposed project, including the so called Gradient Report, the result of an EMF analysis done by Gradient Corp. of Cambridge at the request of National Grid and Eversource, the two companies that are proposing the transmission line.

His report concludes that EMF exposure level for homes along the Wakefield portion of the route would fall below the cutpoints established in those epidemiological studies and well below the exposure limits set by the Institute of Electrical and Electronics Engineers (IEEE) and the International Commission on Non-Ionizing Radiation Protection (ICNIRP).

Based on other scientific studies, Kavet further concludes that there is insufficient evidence to conclude that EMF exposure is is a causal factor in childhood leukemia or other health issues.

In his report, Kavet goes into the fundamentals of magnetic fields and the background of EMF health research. He also cites scientific studies that have failed to find a biophysical mechanism linking EMF at residential levels to childhood leukemia as well as the results of long-term animal studies that have failed to show a connection between EMF and cancer.

“In the late 1980s-early 1990s the results of several epidemiology studies had spurred concerns regarding potential health effects from power frequency magnetic fields,” Kavet writes. “Although there were no biophysical mechanisms known to explain biological effects of fields of the magnitude typical of residences (and there are still none), it was nonetheless a high priority to characterize the magnetic fields within residential environments (and others, such as workplaces, schools, day care centers, etc.), as well as the sources of those fields.”

According to Kavet’s report, the ‘modern era’ of health research on power frequency electric and magnetic fields (EMF) dates back to the 1970s with the advent of transmission lines rated at voltages of up to 765 kV. He notes that a 1979 study was the first to suggest a possible link between power lines and childhood cancer. However Kavet notes that the study included few residents near overhead transmission lines but rather looked at proximity to lower voltage distribution lines. He also stresses that factors beyond just an “association” must be present to establish a causal relationship.

Kavet cites a later federal EMF research program initiated under the 1992 Energy Policy Act and managed by the National Institute of Environmental Health Sciences, which submitted its final report to the US Congress in 1999.

Kavet quotes from that report. “The scientific evidence suggesting that ELF-EMF exposures pose any health risk is weak.” The report points to the limits of epidemiological studies and notes that virtually all of the laboratory evidence in animals and humans and most of the mechanistic work done in cells fail to support a causal relationship between exposure to EMF at environmental levels and disease.

He also cited a 2007 World Health Organization analysis of all aspects of EMF heath research, including cancer. The report concluded that, “on balance, the evidence is not strong enough to be considered causal, but sufficiently strong to remain a concern.”

Kavet notes that of all the childhood leukemia epidemiology studies, only one conducted in the UK was concerned exclusively with underground transmission lines. “Though this study produced no evidence suggestive of excess risk associated with either proximity to underground lines or calculated fields, the number of subjects was small, producing relatively imprecise estimates of relative risk,” Kavet adds.

He quotes a 2012 European study that concluded, “There is limited evidence for an association between magnetic fields and the risk of leukemia in children…but the observed association alone is not sufficient to conclude a causal relationship.”

Kavet refers to a report by an expert panel of European scientists that reviewed the EMF literature since 2007 with updates published on a continuing basis. The last report, published in 2015 concluded: that “Overall, existing studies do not provide convincing evidence for a causal relationship between EMF exposure and self-reported symptoms.”

He also discusses the levels of EMF to which homes in the United States are typically exposed. Noting that magnetic fields are measured in units of “milligauss” (mG), he cites a 1993 study which showed that 5.1 percent of households have have magnetic field exposure greater than 3 mG and just 2.8 percent are above 4 mG. Those are the the two primary cutpoints used in the epidemiology studies of EMF exposure.

Kavet also produced tables showing what exposure levels would be at various distances from the proposed Wakefield transmission line. He notes that house-to-line distances were available for 32 houses on Salem Street. Based on the data, Kavet concludes that “Under average loading conditions of 100 A, all of the residences along Salem Street would be below the 3- and 4-mG cutpoints used in the epidemiological analyses. It is reasonable to expect similar results for New Salem Street, but a definitive statement is not possible without the appropriate data.”

Moving on to animal studies, Kavet cites a National Toxicology Program study released in 1999.

He notes that in these long-term studies, 100 rats and mice of each sex were exposed to either 0 mG, 20 mG, 2,000 mG and 10,000 mG plus 10,000 mG with one hour on followed by one hour off. For rats, the authors stated: “These data, when considered as a whole, are interpreted as indicating that chronic exposure to pure linearly polarized 60 Hz magnetic fields has little or no effect on cancer development.” For mice: “These data do not support the hypothesis that chronic exposure to pure, linearly polarized 60 Hz magnetic fields is a significant risk factor for neoplastic development in mice.”

Finally, Kavet addresses the issue of mitigating the levels of EMF along the length of the route in Wakefield. He discusses two engineering strategies possible for mitigating exposure levels from a theoretical perspective: (1) increasing the line’s burial depth, and (2) compacting the conductors.

While noting that hypothetical scenarios indicate that each or both of these measures would mitigate magnetic field levels above the ground, Kavet notes that other factors may have to be considered.

“Either or both of these options may pose collateral issues that either limit or nullify their respective feasibilities,” Kavet writes. “For example, and as indicated in the docket, selecting a greater burial depth may entail excavating into pre-existing infrastructure, or compaction may create thermal stresses beyond the cables’ tolerances.”

He goes on to say that an alternative measure to mitigate the magnetic field is to use HPFF cable instead of XLPE. “However,” Kavet concludes, “The recommendations and decisions for their implementation go beyond the scope of this report, involving other factors as deliberated in the docket proceedings.”

Kavet will be at the Board of Selectmen’s meeting on Monday, Feb. 12, to discuss his report.

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