Prospective Study of Occupation and Amyotrophic Lateral Sclerosis Mortality

Abstract

Occupational exposures are suspected of contributing to the risk of amyotrophic lateral sclerosis (ALS), but results of epidemiologic studies have been inconsistent. The authors prospectively assessed the relation between occupation and ALS mortality among more than 1 million participants in the Cancer Prevention Study II of the American Cancer Society. Follow-up from 1989 through 2002 identified 507 ALS deaths among men and 430 among women. Adjusted rate ratios were calculated by using Mantel-Haenszel weights and Cox proportional hazards. Among men, elevated ALS mortality was found for programmers (rate ratio = 4.55, 95% confidence interval: 1.46, 14.2; p = 0.009) and laboratory technicians (rate ratio = 1.96, 95% confidence interval: 1.04, 3.66; p = 0.04). Occupations previously associated with increased risk of ALS for which no increased risk was found included farmers, electricians, and welders, although the numbers of electricians (eight ALS deaths) and welders (two ALS deaths) were small. Among women, only machine assemblers had significantly increased ALS mortality (rate ratio = 2.81, 95% confidence interval: 1.05, 7.53; p = 0.04). Results, which suggest that male programmers and laboratory technicians and female machine assemblers may be at increased risk of death from ALS, should be interpreted cautiously, however, because they are based on small numbers.

Epidemiology of amyotrophic lateral sclerosis patients in a centre in Buenos Aires

“…Some of them have associated certain work activities with an increased risk for the disease, like football players and war veterans 19,20 . Others activities that have been associated with sALS risk factor are veterinarians, health workers, athletes, hairdressers, power-production plant workers and electricians 21,22 . In our series, we used the International Standard Classification of Occupation (ISCO), which is a coding system that classifies jobs into occupational groups according to similarity in skill levels and specialization of tasks and duties performed.…”

Environmental and Occupational Risk Factors for Amyotrophic Lateral Sclerosis: A Case-Control Study

“…Exact logistic regression was performed to explore the association of exposure to individual metals and pesticides with risk of ALS. Earlier studies have suggested a relationship between education and ALS; therefore, final conditional logistic regression models were fit adjusting for smoking (ever vs. never) and education (high school or less vs. more than high school) [26,27]. SPSS (Statistical Package for the Social Sciences) version 19 (IBM, Chicago, Ill., USA) and SAS (Statistical Analysis System) version 9.3 (SAS Institute Inc., Cary, N.C., USA) were used to conduct all statistical analyses [36,37].…”

“…The relationship between exposure to pesticides, agricultural occupations and residing in a rural area and risk of ALS has been inconsistent as only about half of the epidemiologic studies, including two meta-analyses, have found an association [14,20,21,22,23,24,25]. However, this finding has not been replicated by some studies [26,27,28,29]. The association of occupational electromagnetic field exposure with ALS has also been investigated, with most published reports indicating a positive relationship [30].…”

Conjugal amyotrophic lateral sclerosis in Brazil

“…Thus, ALS has appeared associated with heavy manual work, electric trauma, and employment in the plastic industry, exposure to heavy metals, acids and animal carcasses, high increased exercises as seen in soccer players in Italy 11,12 . Besides genetic and environmental factors, the existence of a yet-unidentified transmissible agent cannot be excluded.…”