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.
"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). "
[Show abstract][Hide abstract] ABSTRACT: Background:
Amyotrophic lateral sclerosis (ALS) is a serious and rapidly fatal neurodegenerative disorder with an annual incidence of 1-2.6/100,000 persons. Few known risk factors exist although gene-environment interaction is suspected. We investigated the relationship between suspected neurotoxicant hazardous air pollutants (HAPs) exposure and ALS.
A case-control study involving sporadic ALS cases (n = 51) and matched controls (n = 51) was conducted from 2008 to 2011. Geocoded residential addresses were linked to U.S. EPA NATA data (1999, 2002, and 2005) by census tract. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using conditional logistic regression.
Residential exposure to aromatic solvents significantly elevated the risk of ALS among cases compared to controls in 2002 (OR = 5.03, 95% CI: 1.29, 19.53) and 1999 (OR = 4.27, 95% CI: 1.09, 16.79) following adjustment for education, smoking, and other exposure groups. Metals, pesticides, and other HAPs were not associated with ALS.
A potential relationship is suggested between residential ambient air aromatic solvent exposure and risk of ALS in this study.
"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 , in Australia the level of literacy is high (http://www.abs.gov.au/ausstats), 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. "
[Show abstract][Hide abstract] ABSTRACT: The cause of sporadic amyotrophic lateral sclerosis (SALS) remains unknown. We attempted to find out if occupational exposure to toxicants plays a part in the pathogenesis of this disease. In an Australia-wide case-control study we compared the lifetime occupations of 611 SALS and 775 control individuals. Occupations were coded using country-specific as well as international classifications. The risk of SALS for each occupation was calculated with odds ratios using logistic regression. In addition, the literature was searched for possible toxicant links between our findings and previously-reported occupational associations with SALS. Male occupations in our study that required lower skills and tasks tended to have increased risks of SALS, and conversely, those occupations that required higher skills and tasks had decreased risks of SALS. Of all the occupations, only truck drivers, where exposure to diesel exhaust is common, maintained an increased risk of SALS throughout all occupational groups. Another large case-control study has also found truck drivers to be at risk of SALS, and almost two-thirds of occupations, as well as military duties, that have previously been associated with SALS have potential exposure to diesel exhaust. In conclusion, two of the largest case-control studies of SALS have now found that truck drivers have an increased risk of SALS. Since exposure to diesel exhaust is common in truck drivers, as well as in other occupations that have been linked to SALS, exposure to this toxicant may underlie some of the occupations that are associated with SALS.
PLoS ONE 11/2013; 8(11):e80993. DOI:10.1371/journal.pone.0080993 · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Along with the wide use of pesticides in the world, the concerns over their health impacts are rapidly growing. There is a huge body of evidence on the relation between exposure to pesticides and elevated rate of chronic diseases such as different types of cancers, diabetes, neurodegenerative disorders like Parkinson, Alzheimer, and amyotrophic lateral sclerosis (ALS), birth defects, and reproductive disorders. There is also circumstantial evidence on the association of exposure to pesticides with some other chronic diseases like respiratory problems, particularly asthma and chronic obstructive pulmonary disease (COPD), cardiovascular disease such as atherosclerosis and coronary artery disease, chronic nephropathies, autoimmune diseases like systemic lupus erythematous and rheumatoid arthritis, chronic fatigue syndrome, and aging. The common feature of chronic disorders is a disturbance in cellular homeostasis, which can be induced via pesticides' primary action like perturbation of ion channels, enzymes, receptors, etc., or can as well be mediated via pathways other than the main mechanism. In this review, we present the highlighted evidence on the association of pesticide's exposure with the incidence of chronic diseases and introduce genetic damages, epigenetic modifications, endocrine disruption, mitochondrial dysfunction, oxidative stress, endoplasmic reticulum stress and unfolded protein response (UPR), impairment of ubiquitin proteasome system, and defective autophagy as the effective mechanisms of action.
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