Occupational Exposure Assessment in Epidemiological Studies of EMF (invited paper)

Numerous epidemiological studies have examined associations between occupational exposures to electric and magnetic fields (EMF) and adult cancers, with a particular focus on leukaemia and brain cancer. Meta-analyses that explored the patterns of these results with a particular emphasis on the qualitative aspects of exposure assessment are reviewed. Comparative analysis of the studies of electric utility employees are presented, along with an assessment of whether methodological differences among the studies might explain reported inconsistencies. Exposure assessment remains a foremost challenge in EMF studies. Most epidemiological studies have relied on magnetic field measurements linked to job titles. However, job titles alone explain only a small amount of variability in exposure. Recent results indicate that magnetic field exposure assessment should consider work environment in addition to job title to reduce exposure misclassification. The paper concludes with a discussion of numerous difficulties in occupational exposure assessment and offers suggestions for research. (author)