Exposure to environmental toxins and the risk of sporadic motor neuron disease: an expanded Australian case-control study

Background and purpose It remains unclear what role environmental toxins play in sporadic motor neuron disease (SMND) and its most common subtype, amyotrophic lateral sclerosis (SALS). Most previous studies of this issue have contained only small numbers of SMND cases. We sought to re-examine possible associations between toxins and SMND in a large Australian casecontrol study. Methods Questionnaire data were available from 787 patients with SMND (614 with SALS) and 778 non-related controls. Individuals were asked whether they had been exposed to metals or chemicals/solvents at work or to herbicides/pesticides. Chi-square tests with odds ratios and 95% confidence intervals were calculated for responses, and significance levels were corrected for multiple testing. Results Men were more likely to acquire SALS if they worked with metals (OR similar to=similar to 1.95, 95% CI similar to=similar to 1.243.07) or chemicals/solvents (OR similar to=similar to 1.96, 95% CI similar to=similar to 1.462.61) or if they had been exposed to herbicides or pesticides (OR similar to=similar to 1.77, 95% CI similar to=similar to 1.302.39). Women who had worked with chemicals or solvents also appeared to be at increased risk of acquiring SALS (OR similar to=similar to 1.71, 95% CI similar to=similar to 1.222.40). Conclusions These results support previous reports that exposures to metals or chemicals are associated with SMND. A suggested protocol for future multinational studies of environmental toxins and SMND is presented.