Exposure to power-frequency magnetic fields and the risk of childhood cancer

Background Previous studies have suggested an association between exposure to power-frequency electromagnetic fields (EMF) and the development of chil dhood malignant disease, especially leukaemia and tumours of the central ne rvous system. We investigated the relation between all childhood cancer and exposure to power-frequency magnetic fields. Methods The UK Childhood Cancer Study was a population case-control study c overing the whole of England, Wales, and Scotland. All children with a conf irmed malignant disorder were potentially eligible. For each case, we match ed two controls on date of birth and sex, randomly chosen from the list of the Family Health Services Authority in England and Wales or Health Board i n Scotland. In the main study, 3838 cases and 7629 controls were interviewe d. The EMF part of the study included only one control per case, and househ old EMF measurements and school measurements where relevant were taken on 2 226 matched pairs. These measurements, adjusted for historical line load an d appliance fields, were used to estimate average exposure in the year befo re the date of diagnosis, or an equivalent date for controls. Analyses were by conditional logistic regression, incorporating a census-derived depriva tion index used as a measure of socioeconomic status. Findings For children with mean exposures of more than 0.2 mu T compared wi th children with mean exposures of less than 0.1 mu T, the adjusted odds ra tios were 0.92 (95% CI 0.47-1.79) for acute lymphoblastic leukaemia, 0.90 ( 0.49-1.63) for all leukaemia, 0.46 (0.11-1.86) for central-nervous-system t umours, 0.97 (0.46-2.05) for other malignant disease, and 0.87 (0.56-1.35) for all malignant disease combined. Higher exposures (>04 mu T) were record ed for only 17 (<0.4%) individuals (eight cases, nine controls). Interpretation This study provides no evidence that exposure to magnetic fi elds associated with the electricity supply in the UK increases risks for c hildhood leukaemia, cancers of the central nervous system, or any other chi ldhood cancer.