Commentary: Magnetic field exposure and childhood leukaemia—moving the research agenda forward

Abstract

Nevertheless, the relationship remains questionable because the risks were observed at exposure levels where biological effects are not assumed to occur. 4 Animal data have mostly been negative and a plausible and reproducible biological mechanism is still lacking. 5 Studies on adult leukaemia in populations with much higher occupational ELF-MF exposures are inconclusive, though a trend towards an increased risk among highly exposed workers has been noted by the International Commission on Non-IonizingRadiationProtection. 3 Thus, there isongoingdebate among scientists as to whether the observed statistical association between incidence of childhood leukaemia and exposure to residential ELF-MF is primarily due to bias. Three main sources of bias have been identified as being potentially important to this field of inquiry: confounding, exposure misclassification, and selection bias. It has previously been shown that confounding due to an unknown, aetiologically relevant correlate of ELF-MF levels (e.g. traffic density) is unlikely to be important in this context. 6,7 Exposure misclassification is likely to be non-differential and is expected to result in an underestimation of the true exposure–response association. 7