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Paul Elliott, Mireille Toledano and Kees de Hoogh, Imperial College London and Gavin Shaddick, University of Exeter
Also, formerly:
David Briggs, Catherine Keshishian and Nina Iszatt, Imperial College London and John Swanson, National Grid Transco PLC
(Project no. 0301047, previously 30104)
The study involves estimating residential exposure to overhead powerlines in relation to risk of certain types of cancer. In order to better inform exposure estimates, the migration pattern of individuals living near powerlines over time is required.
Since 1979 (1) there has been concern that the extremely low frequency electromagnetic fields (ELF-EMF) produced by powerlines could be associated with cancer, although studies have shown mixed results. On the basis of analyses of the effects of EMF on childhood cancer, the International Agency for Cancer Research classified ELF-EMF as "possibly carcinogenic to humans" (2). Epidemiological studies have mainly been occupational or based on the magnetic fields produced by domestic appliances, however two studies have been conducted into the effects of residential exposure to powerlines. Li et al (1997) (3) estimated that residential exposure to powerlines in Taiwan was associated with a doubling of risk of leukaemia in adults living within 50m of a powerline, and in 2005, Draper et al (4) found a significant increased rate of leukaemia in children living near powerlines in England and Wales. More than 3 million adults live within 1km of a powerline in England and Wales, so a positive association with cancer could have wide public health consequences. Therefore, after a successful pilot study in 1998, we are carrying out a national case-control study to investigate the risk of adult cancer in relation to residential exposure to powerlines.
Our cases include adults aged 15-74 years diagnosed with certain cancers in England and Wales from 1974 to 2003, living within 1km of a powerline. Our controls comprise adult patients diagnosed with other cancers not thought to be related to ELF-EMF. We obtained cancer data from the National Cancer Register held at SAHSU and annual powerline coverage data from National Grid Transco. Two hypotheses for the possible exposure pathways are being investigated. We aim to quantify the risks of adult cancer in relation to overhead powerlines and estimate the number of adults in England and Wales with residential exposure to significant ELF-EMF from powerlines.
(1) Wertheimer N, Leeper E. Electrical wiring configurations and childhood cancer. Am J Epidemiol 1979; 109(3):273-284.
(2) IARC. Non-Ionizing Radiation, Part 1: Static and Extremely Low-Frequency (ELF) Electric and Magnetic Fields. 80, Section 2.3. 7-3-2002. Lyon, France. Monographs on the Evaluation of Carcinogenic Risk to Humans.
(3) Li CY, Theriault G, Lin RS. Residential exposure to 60-Hertz magnetic fields and adult cancers in Taiwan. Epidemiology 1997; 8(1):25-30.
(4) Draper G, Vincent T, Kroll ME, Swanson J. Childhood cancer in relation to distance from high voltage power lines in England and Wales: a case-control study. BMJ 2005; 330(7503):1290.