Pooled analysis of recent studies on magnetic fields and childhood leukaemia

Previous pooled analyses have reported an association between magnetic fields and childhood leukaemia. We presenta pooled analysis based on primary data from studies on residential magnetic fields and childhood leukaemia published after 2000.METHODS: Seven studies with a total of 10 865 cases and 12 853 controls were included. The main analysis focused on 24-h magneticfield measurements or calculated fields in residences.RESULTS: In the combined results, risk increased with increase in exposure, but the estimates were imprecise. The odds ratiosfor exposure categories of 0.1–0.2 mT, 0.2–0.3 mT and X0.3 mT, compared with o0.1 mT, were 1.07 (95% CI 0.81–1.41), 1.16(0.69–1.93) and 1.44 (0.88–2.36), respectively. Without the most influential study from Brazil, the odds ratios increased somewhat.An increasing trend was also suggested by a nonparametric analysis conducted using a generalised additive model.CONCLUSIONS: Our results are in line with previous pooled analyses showing an association between magnetic fields and childhoodleukaemia. Overall, the association is weaker in the most recently conducted studies, but these studies are small and lackmethodological improvements needed to resolve the apparent association. We conclude that recent studies on magnetic fieldsand childhood leukaemia do not alter the previous assessment that magnetic fields are possibly carcinogenic.