Occupational Exposures and Neurodegenerative Diseases-A Systematic Literature Review and Meta-Analyses.
Level 3 - non-randomized controlled study
Systematic review and meta-analysis of observational epidemiological studies
PubMed 30691095 · doi:10.3390/ijerph16030337
What was done
The authors conducted an updated systematic literature review and stratified meta-analysis of 66 epidemiological publications evaluating occupational exposures to electromagnetic fields, metals, and pesticides in relation to amyotrophic lateral sclerosis, Alzheimer's disease, and Parkinson's disease. Following MOOSE and GRADE guidelines, analyses stratified results by publication year, statistical precision of relative risk estimates, funnel plot inspections, and bias testing.
What was found
For electromagnetic fields across 19 studies, the weighted relative risk was 1.26 (95% CI 1.07-1.50) for ALS, 1.33 (95% CI 1.07-1.64) for Alzheimer's disease, and 1.02 (95% CI 0.83-1.26) for Parkinson's disease. For pesticides across 31 studies, the weighted relative risk was 1.35 (95% CI 1.02-1.79) for ALS, 1.50 (95% CI 0.98-2.29) for Alzheimer's disease, and 1.66 (95% CI 1.42-1.94) for Parkinson's disease. For metals across 14 studies, lead exposure in 5 studies had a weighted relative risk of 1.57 (95% CI 1.11-2.20) for ALS or Parkinson's disease, whereas non-lead metal exposures had a weighted relative risk of 0.97 (95% CI 0.88-1.06).
Why it matters
This review synthesizes observational findings across several decades to quantify workplace hazard risks for major neurodegenerative diseases and identify specific exposures of concern.
Limits
All included data derive from observational studies vulnerable to residual confounding, exposure misclassification, and recall bias. The confidence interval for pesticide exposure and Alzheimer's disease crossed the null value, lead exposure analysis relied on only five studies grouping two distinct diseases, and total participant counts were not reported in the abstract.
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