Commentary on epidemiological evidence for an association between exposure to 50 and 60 Hz magnetic fields and cancer.
Hydro-Electric Development: Environmental Impacts, James Bay Publication Series, Paper No. 6. Karamessines, C, ed., Montreal, Quebec, Canada: North Wind Information Services, Inc., 1994 Nov; :18-19
My concern as an occupational health researcher has been measuring magnetic field exposures in order to assess the possible health risk for workers. Dr. Carpenter's review demonstrates that exposure assessments have been particularly important in deciding whether 50/60 Hz magnetic fields are a risk factor for cancer. When Savitz et al. (1987) and London et al. (1991) took short-term area measurements of the magnetic field, no associations with childhood cancer risks were found. However, a significant association with leukemia in children was revealed when Feychting and Ahlbom (1993) calculated historical averages of the magnetic field in the home. These results are consistent with the theorem that non-differential or random errors in the exposure assessment tends to bias risk estimates in most cases towards the null hypothesis (i.e., no association with the exposure (Armstrong, 1990). To address the question of occupational cancer risk, the most important epidemiological evidence therefore comes from studies with the best exposure assessment: full-shift personal measurements of magnetic fields. Dr. Carpenter reviews four such studies (Table III) which examine workers from all occupations in central Sweden (Floderus et al., 1993), telephone workers (Matanoski et al., 1993), and electric utility workers (Sahl et al., 1993); Theriault et al., 1994). In addition, a new study of electrical occupations by London et al. (1994) reports that magnetic field exposures above 0.18 microT (1.8 mG) have a leukemia odds ratio of 1.3 (1.0-1.6). Taken together, these studies provide some evidence that time-weighted average magnetic fields above 0.2 microT (2 mG) are weakly associated with leukemia and, to a lesser degree, with brain tumours.
Magnetic-fields; Electrical-fields; Cancer; Leukemogenesis; Hematopoietic-system; Brain-tumors; Children; Epidemiology; Exposure-assessment; Exposure-levels; Risk-analysis; Risk-factors; Electromagnetic-fields; Electrical-workers; Public-utilities; Telephone-operators; Occupations; Time-weighted-average-exposure
Hydro-Electric Development: Environmental Impacts