Residential exposure to electromagnetic fields and childhood leukaemia: a meta-analysis

Although individual epidemiological investigations have suggested associati ons: between residential exposure to electromagnetic fields (EMFs) and chil dhood leukaemia, overall the findings have been inconclusive. Several of th ese studies do, however, lend themselves to application of the meta-analysi s technique. For this purpose we carried out searches using MEDLINE and oth er sources, and 14 case-control studies and one cohort study were identifie d and evaluated for epidemiological quality and included in the mete-analys is. Relative risk estimates were extracted from each of the studies and poo led. Separate meta-analyses were performed on the basis of the assessed EMF exposure (wiring configuration codes, distance to power distribution equip ment, spot and 24-h measures of magnetic field strength (magnetic flux dens ity) and calculated magnetic field), the meta-analysis based on wiring conf iguration codes yielded a pooled relative risk estimate of 1.46 (95% confid ence interval (Cl) = 1.05-2.04, P = 0.024) and for that for exposure to 24- h measurements of magnetic fields, 1.59 (95% CI = 1.14-2.22, P = 0.006), in dicating a potential effect of residential EMF exposure on childhood leukae mia. In most cases, lower risk estimates were obtained by pooling high-qual ity studies than pooling low-quality studies. There appears to be a clear t rend for more recent studies to be of higher quality. Enough evidence exist s to conclude that dismissing concerns about residential EMFs and childhood leukaemia is unwarranted. Additional high-quality epidemiological studies incorporating comparable measures for bath exposure and outcomes are, howev er, needed to confirm these findings and, should they prove to be true, the case options for minimizing-exposure should be thoroughly investigated to provide definitive answers for policy-makers.