Case-control study of occupational exposure to electric shocks and magnetic fields and mortality from amyotrophic lateral sclerosis in the US, 1991-1999

We investigated the relationship between occupational exposure to electric shocks (ES) and magnetic fields (MF) and amyotrophic lateral sclerosis (ALS) using 1991-1999 US mortality data. For each of the 5886 included ALS deaths, 10 controls-matched on sex-, age-, year- and region-were selected from among other deaths. Usual occupation as reported on death certificates was linked to job-exposure matrices for ES and MF. Education and electric occupations were associated with moderately increased ALS risks (odds ratio (OR) = 1.85, 95% confidence interval (CI) = 1.67, 2.04; OR = 1.23, 95% CI = 1.04, 1.47, respectively). For ES, ALS mortality OR were 0.73 (95% CI = 0.67, 0.79) for high and 0.90 (95% CI = 0.84, 0.97) for medium exposure compared with low exposure. For MF, ALS ORs were 1.09 (95% CI = 1.00, 1.19) for high and 1.09 (95% CI = 0.96, 1.23) for medium exposure as compared with low exposure. For electric occupations, ALS ORs were insensitive to adjustments for ES, MF or both. Consistent with previous publications, an association between electric occupations and ALS was observed. Findings do not support occupational exposure to ES or MF as an explanation.