'No health hazard from exposure to electric fields'

By Our Science Correspondent

BANGALORE, AUG. 20. Despite hundreds of studies which have been carried out, there is no evidence of any health hazards caused by exposure to high-voltage electric and magnetic fields, according to Dr. P. Sarma Maruvada, a consulting engineer from Canada.

There had been concerns that high-voltage power transmissions could affect the health of people in their vicinity. Initially, the concerns were about shocks people received when they touched vehicles and other large metallic objects near power transmission lines.

Possible health effects due to exposure to power-frequency electric fields became an issue almost 30 years ago when a paper was published in the Soviet Union, says Dr. Maruvada in a keynote speech to be delivered at the four-day International Symposium on High Voltage Engineering which began here today. An epidemiological study published in 1979 in the United States first raised the possibility of cancer being associated with exposure to power-frequency magnetic fields. This triggered an avalanche of studies worldwide on the possible biological effects of short and longer-term exposure to electric and magnetic fields (EMF).

The studies included studies on human volunteers, laboratory work on individual cells, issues and animals as well as epidemiological research. A recent review by the National Research Council concluded that a comprehensive evaluation of published studies showed no evidence that exposure to electrical and magnetic fields presented any human health hazard.

Nevertheless, power utilities were adopting strategies of "prudent avoidance" to reduce human exposure to power-frequency EMF. While reducing the strength of electric fields was comparatively easy, reduction of magnetic fields created by power systems was much more difficult. Conventional shielding would be prohibitively expensive, and a variety of passive and active techniques were developed for substantially reducing the strength of magnetic fields near power systems.

The 12th International Symposium on High Voltage Engineering (ISH) is being held in India for the first time. As it happens, the Indian Institute of Science's Department of High Voltage Engineering, which is hosting the event, is celebrating its golden jubilee this year. Studies in high voltage engineering at the institute go back even further, having started in 1926.

The ISH provides an international forum where those doing basic research can meet and discuss issues with people involved in practical applications, according to Prof. Michael Muir of the Technical University of Graz in Austria, and a member of the ISH's International Steering Committee.

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