[S25.005] Prospective Study of Chemical Exposures and Amyotrophic Lateral Sclerosis Mortality

Marc Weisskopf, Natalia Morozova, Eilis O'Reilly, Marjorie McCullough, Eugenia Calle, Michael Thun, Atlanta, GA, Alberto Ascherio, Boston, MA

OBJECTIVE: To assess the association between exposure to chemicals and risk of amyotrophic lateral sclerosis (ALS) in a prospective cohort study. BACKGROUND: Environmental toxins, including pesticides, are suspected of contributing to the risk of ALS. Results of case-control studies, and genetic studies implicating genes involved in pesticide detoxification provide some support for this hypothesis, but there are no data from large prospective investigations. DESIGN/METHODS: We prospectively assessed the relation between self-report of regular exposure to 12 different chemical classes and ALS mortality among over 1 million participants in the Cancer Prevention Study II of the American Cancer Society. Follow-up from 1989 through 2002 identified 507 deaths from ALS among men and 430 among women. We calculated adjusted rate ratios (RR) using Mantel-Haenszel weights and Cox proportional hazards. RESULTS: There was no difference in risk of ALS mortality by pesticide/herbicide exposure. The RR for ALS mortality among the exposed compared to the unexposed was 1.1 (95% confidence interval (CI): 0.8-1.5). The only exposure that showed an increased RR for ALS was formaldehyde (RR: 1.5; 95% CI: 1.0-2.1). Among those reporting duration of formaldehyde exposure, there was an increasing dose-response relation with increasing years of exposure, with RRs of 1.7 (95% CI: 0.6-4.7), 2.4 (95% CI: 0.9-6.2), and 4.3 (95% CI: 2.1-8.7) for those reporting <4 years, 4-10 years, and >10 years of exposure, respectively, compared to the unexposed (p-trend=0.03). There was little difference by sex. CONCLUSIONS/RELEVANCE: We did not find evidence of an association between pesticides and ALS. In contrast, we found evidence suggesting an increased risk of ALS with formaldehyde exposure. Because of the longitudinal design, this result is unlikely to be due to bias, but it should nevertheless be interpreted cautiously and needs to be independently verified. Supported by: Grant #W81XWH-05-1-0117 from the Department of Defense.
Category - Neuroepidemiology/Health Services and Outcomes Research
SubCategory - Other

Wednesday, April 16, 2008 3:00 PM

Scientific Sessions: Stroke Care Quality; Risk Factors for Neurologic Diseases (2:00 PM-3:30 PM)

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