Occupational exposures and the risk of amyotrophic lateral sclerosis

Abstract

Objectives To examine the associations of specific occupations and occupational exposures with the risk of amyotrophic lateral sclerosis (ALS) in the Swedish population. Methods A nested case-control study was conducted in Sweden. ALS patients diagnosed during 1991–2010 (n=5,020) were identified from the National Patient Register and five controls per case (n=25,100) were randomly selected from the general Swedish population, individually matched to cases by birth year and sex. Occupational history was obtained from the Swedish Censuses in 1970, 1980, and 1990. The Nordic Occupational Cancer Study Job Exposure Matrix was used to identify exposures related to individual occupations. Conditional logistic regression was used to estimate odds ratios (ORs) and their 95% confidence intervals (CIs). Results Higher risk of ALS was associated with precision-tool manufacturing (OR: 1.68, 95% CI: 1.11, 2.52) and glass, pottery and tile work (OR: 1.76, 95% CI: 1.03, 3.00), whereas lower risk was associated with textile work (OR: 0.44, 95% CI: 0.21, 0.91). None of the examined occupational exposures were associated with ALS risk overall. However, among individuals younger than 65 years of age, an association with a higher risk of ALS was found for formaldehyde (OR: 1.29, 95% CI: 1.00, 1.65), and an association with a lower risk of ALS was found for methylene chloride (OR: 0.49, 95% CI: 0.26, 0.93). Conclusions We identified several occupations and occupational exposures that may be associated with the risk of ALS in Sweden. Occupational history obtained from censuses every ten years remains a limitation of the study.

Amyotrophic Lateral Sclerosis and Occupational Exposures: A Systematic Literature Review and Meta-Analyses

“…The weighted RR was 1.35 (95% CI 1.02–1.79). Exposure to other chemicals was considered in eight studies [24,27,38,40,42,43,49,52] and the weighted RR was 1.14 (95% CI 1.02–1.28). The two exposure strata had similar heterogeneity as the combined data and their RRs were not different in the meta-regression test, p = 0.44.…”

“…The weighted RR for exposure to lead [21,35,42] was 1.51 (95% CI 0.96–2.38) and exposure to metals from different sources (plants, shipyards, grinding) [24,27,38] resulted in a weighted RR of 1.43 (95% CI 0.95–2.14). The overall weighted RR was statistically significantly elevated at 1.45 (95% CI 1.07–1.96) (Figure 4).…”

“…Only studies [18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54] fulfilling good scientific standards (Armon class II or III) were used in our meta-analyses; see Table 1. Another 46 relevant publications [3,9,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,…”

Occupational causes of amyotrophic lateral sclerosis: where to from here?

“…The paper by Peters et al 8 in this issue of the journal is therefore potentially of considerable interest. It involves a case–control study conducted in Sweden during 1991–2010 which used the Nordic Occupational Cancer Study job-exposure matrix (NOCCA-JEM) to identify exposures related to individual occupations.…”

Occupational physician and amyotrophic lateral sclerosis: needs and training and information tools

“…Although some neurotoxic effects have been known for a long time, their role in neurodegeneration and in neurodegenerative diseases was understood recently. Studies in literature on the relationship between occupational and environmental exposures, and Amyotrophic Lateral Sclerosis are various and range from clinical or occupational case reports to case control studies, retrospective cohort studies and prospective, based on clinical data and death certificates and do not allow at the moment definitive conclusions (1,8,9). Exposure to pesticides has been assessed in several case-control studies (10)(11)(12)(13)(14)(15)(16) and in a cohort study (17); the exposure is generally associated with an increased risk in case-control studies, although the relationship was not always statistically significant.…”