Adult glioma in relation to residential power frequency electromagnetic field exposures in the San Francisco Bay area

In a population-based study, we examined residential power frequency electr omagnetic field exposures for 492 adults newly diagnosed with histologicall y confirmed glioma between Au gust 1, 1991 and April 30, 1994, in the San F rancisco Bay area and 462 controls, obtained through random-digit dialing f requency, matched to cases for age, gender, and race Residential exposure a ssessment consisted of spot measures with EMDEX (Enertech Consultants, Camp bell, CA) meters and wire codes based on characterization and location of n earby power lines. We considered the index residence at the time of the cas e's diagnosis or the control's interview and all other California residence s of each subject for 7 years before study entry. We obtained wire codes fo r eligible residences of 76% and for index residences of 99% of subjects. U sing the Kaune-Savitz wire code classification, the relative risk for longe st held residences coded as "high" compared with "low" was 0.9 [95% confide nce interval (CI) = 0.7-1.3], while relative risk and 95% CIs for front doo r spot measures of 1.01-2 milligauss, 2.01-3 milligauss, and higher than 3 milligauss compared with less than or equal to 1 milligauss were 1.0 (0.7-1 .4), 0.6 (0.3-1.1), and 1.7 (0.8-3.6). Adjustment for age, gender, race, an d whether the subject owned the residence did not meaningfully alter these findings, nor did comparisons using index or highest coded residence. Becau se of potential exposure misclassification and the unknown pertinent exposu re period, these data cannot provide strong support against, but clearly do not support an association between, adult glioma and residential power fre quency electromagnetic field exposures.