Occupational exposure to electromagnetic fields and adult leukaemia: A review of the epidemiological evidence

The relationship between occupational exposure to extremely low-frequency electromagnetic fields and adult leukaemia has been studied extensively during the last decade. The first studies were based on crude exposure assessments, estimated through job titles, with no or only limited control of confounding factors. The results were often inconsistent, indicating no effects in about 50% of the studies, while the other half showed only small to moderate effects. Concern has been raised that crude exposure-assessment methods might have diluted the effect estimates, and that improvement of the methods used for exposure assessment would result in more consistent associations. The present review emphasises the latest studies with considerably improved exposure assessments, as well as the control of confounding factors. Results from studies where exposure was assessed through measurements of the magnetic fields at the workplace are still inconsistent. These studies provide some support for the hypothesis of an association between magnetic field exposure and adult leukaemia, especially for chronic lymphocytic leukaemia, but inconsistencies between and within studies weaken the evidence. The lack of consistency regarding the type of leukaemia associated with magnetic field exposure might be explained by differences between the study designs or the populations studied, but based on the existing evidence, no firm conclusions can be drawn.