Supplementary Material for: Environmental and Occupational Exposures and Amyotrophic Lateral Sclerosis in New England

Background: Recent data provide support for the concept
that potentially modifiable exposures are responsible for sporadic
amyotrophic lateral sclerosis (ALS). Objective: To evaluate environmental and occupational exposures as risk factors for sporadic ALS. Methods:
We performed a case-control study of ALS among residents of New
England, USA. The analysis compared questionnaire responses from 295
patients with a confirmed ALS diagnosis to those of 225 controls without
neurodegenerative illness. Results: Self-reported job- or
hobby-related exposure to one or more chemicals, such as pesticides,
solvents, or heavy metals, increased the risk of ALS (adjusted OR 2.51;
95% CI 1.64-3.89). Industries with a higher toxicant exposure potential
(construction, manufacturing, mechanical, military, or painting) were
associated with an elevated occupational risk (adjusted OR 3.95; 95% CI
2.04-8.30). We also identified increases in the risk of ALS associated
with frequent participation in water sports, particularly waterskiing
(adjusted OR 3.89; 95% CI 1.97-8.44). Occupation and waterskiing both
retained independent statistical significance in a composite model
containing age, gender, and smoking status. Conclusions:
Our study contributes to a growing body of literature implicating
occupational- and hobby-related toxicant exposures in ALS etiology.
These epidemiologic study results also provide motivation for future
evaluation of water-body-related risk factors.