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

The Stacey Motor Neuron Disease Laboratory, Department of Pathology, The University of Sydney, Sydney, NSW, Australia.
European Journal of Neurology (Impact Factor: 4.06). 05/2012; 19(10):1343-8. DOI: 10.1111/j.1468-1331.2012.03769.x
Source: PubMed


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 case-control study.
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.
Men were more likely to acquire SALS if they worked with metals (OR = 1.95, 95% CI = 1.24-3.07) or chemicals/solvents (OR = 1.96, 95% CI = 1.46-2.61) or if they had been exposed to herbicides or pesticides (OR = 1.77, 95% CI = 1.30-2.39). Women who had worked with chemicals or solvents also appeared to be at increased risk of acquiring SALS (OR = 1.71, 95% CI = 1.22-2.40).
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.

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    • "One study also included a panel of industrial hygienists (McGuire et al., 1997). Some studies have reported a significant association between exposure to solvents or occupations involving solvent exposure and ALS or MND (Morahan and Pamphlett, 2006; Chio et al., 1991; Chancellor et al., 1993; Graham et al., 1997; Park et al., 2005; Pamphlett, 2012), while others have not (Malek et al., 2014; McGuire et al., 1997; Fang et al., 2009; Gunnarsson et al., 1992; Hawkes and Fox, 1981; Gait et al., 2003; Strickland et al., 1996; Savettieri et al., 1991; Granieri et al., 1988; Welp et al., 1996; Gunnarsson et al., 1991). Two studies reported increased mortality from MND among leather workers (Hawkes and Fox, 1981; Buckley et al., 1983), but another did not find this association (Gunnarsson and Lindberg, 1989; Martyn, 1989). "
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    • "For example, neither active military service, nor whether service was in the army, navy or air force, could be determined; (6) a difference in levels of education between patients and controls could lead to differences in the way the questionnaire was completed. However, as has been noted before in relation to this cohort [46], in Australia the level of literacy is high (, with free compulsory education until the age of 17 years. Close matching of cases and controls (e.g., partners) would add to the likelihood of similar education and social levels. "
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