Speaker
Description
During more than four decades, there has been a discussion about whether exposure to extremely low frequency (ELF) magnetic fields (MF) below guideline levels may be associated with an increased risk of childhood leukaemia. Results from epidemiological studies have unusually consistently showed an increased risk. Original data from studies of ELF-MF and childhood leukaemia of sufficient quality have been included in consecutive pooled analyses allowing harmonized exposure definitions and cutpoints, and a similar effort has been done for distance to power lines. There is evidence from these pooling efforts, and from individual studies that cover a long calendar period, suggesting that the association between ELF-MF and childhood leukaemia has declined over time. This decline is unlikely to be explained by changes in study quality. It could be a true causal association that has declined over time, or an association that was biased by confounding from an unknown risk factor for childhood leukaemia which has declined in prevalence over time or is no longer associated with ELF-MF, or simply random variation. Further research would be needed to determine the reason for the decline.
