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Original article
Study of occupation and amyotrophic lateral sclerosis in a Danish cohort
  1. Aisha S Dickerson1,2,
  2. Johnni Hansen3,
  3. Marianthi-Anna Kioumourtzoglou4,
  4. Aaron J Specht2,
  5. Ole Gredal3,
  6. Marc G Weisskopf1,2
  1. 1 Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
  2. 2 Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
  3. 3 Danish Cancer Society, Institute of Cancer Epidemiology, Copenhagen, Denmark
  4. 4 Department of Environmental Health Sciences, Columbia University Mailman School of Public Health, New York, USA
  1. Correspondence to Dr Aisha S Dickerson, Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; adickerson{at}


Objectives Several manuscripts have proposed associations between amyotrophic lateral sclerosis (ALS) and occupational toxicant exposures—not to mention physical activity and trauma/injury. Some have also reported associations in investigations of specific occupations. Using data from a prospective Danish cohort study, we investigated the association between employment in certain industries and ALS diagnosis.

Methods We identified 1826 ALS cases who were 25 years old or less in 1964 and diagnosed from 1982 to 2013 from the Danish National Patient Registry then matched 100 population controls to each case based on birth year and sex. Demographic data were linked to the Danish Pension Fund to determine occupation history. Conditional logistic regression models were adjusted for socioeconomic status, marital status and residential location at the index date.

Results There was an increase in odds of ALS among men who worked in agriculture, hunting, forestry or fishing (adjusted OR (aOR)=1.21; 95% CI 1.02 to 1.45). There was also a positive association for men employed in construction (aOR=1.21; 95% CI 1.05 to 1.39). In women, a protective association was seen with employment in the cleaning industry (aOR=0.69; 95% CI 0.52 to 0.93).

Conclusions Our study shows various occupations with exposure to toxicants, such as diesel exhaust and lead, and strenuous physical activity associated with increased odds of ALS in men. Future studies should have a particular focus on gathering detailed information on physical exertion and toxicant exposures specific to certain job tasks.

  • epidemiology
  • environment
  • international occupational health
  • amyotrophic lateral sclerosis
  • neurodegeneration
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  • Contributors MGW and JH: designed the study and directed its implementation. JH and OG: gathered data. ASD: performed data analysis and drafted the article. M-AK and MGW contributed to the analyses. AJS: reviewed and revised the analysis results. MGW, JH, AJS and MAK revised the manuscript.

  • Funding This work was supported by the National Institute of Environmental Health Sciences (grant R01 ES019188). ASD was supported in part by an NIH training grant (grant T32 ES007069).

  • Competing interests None declared.

  • Patient consent Not required.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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