Occupational Exposures and Neurodegenerative Diseases—A Systematic Literature Review and Meta-Analyses

Abstract

Objectives: To carry out an integrated and stratified meta-analysis on occupational exposure to electromagnetic fields (EMFs), metals and pesticides and its effects on amyotrophic lateral sclerosis (ALS) and Parkinson’s and Alzheimer’s disease, and investigate the possibility of publication bias. Methods: In the current study, we updated our recently published meta-analyses on occupational exposures in relation to ALS, Alzheimer’s and Parkinson’s disease. Based on 66 original publications of good scientific epidemiological standard, according to the Meta-analysis of Observational Studies in Epidemiology (MOOSE) and the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) guidelines, we analysed subgroups by carrying out stratified meta-analyses on publication year, statistical precision of the relative risk (RR) estimates, inspection of the funnel plots and test of bias. Results: Based on 19 studies the weighted RR for occupational exposure to EMFs was 1.26 (95% confidence interval (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. Thirty-one studies concerned occupational exposure to pesticides and the weighted RR 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. Finally, 14 studies concerned occupational exposure to metals and only exposure to lead (five studies) involved an elevated risk for ALS or Parkinson’s disease and the weighted RR was 1.57 (95% CI 1.11–2.20). The weighted RR for all the non-lead exposures was 0.97 (95% CI 0.88–1.06). Conclusions: Exposure to pesticides increased the risk of getting the mentioned neurodegenerative diseases by at least 50%. Exposure to lead was only studied for ALS and Parkinson’s disease and involved 50% increased risk. Occupational exposure to EMFs seemed to involve some 10% increase in risk for ALS and Alzheimer’s disease only.

Neuropathological Mechanisms Associated with Pesticides in Alzheimer’s Disease

“…Systematic reviews and meta-analyses of reported epidemiological links have been presented [38,51,52]. A meta-analysis of past reports in 2016 (which included 3 cohort studies and 4 case-control studies) has concluded that pesticide exposure is positively associated with AD (OR, 95% CI: 1.34, 1.08-1.67) [51].…”

“…A meta-analysis of past reports in 2016 (which included 3 cohort studies and 4 case-control studies) has concluded that pesticide exposure is positively associated with AD (OR, 95% CI: 1.34, 1.08-1.67) [51]. Another, more recent meta-analysis in 2019 of 19 studies of occupational exposures to multiple agents on neurodegenerative diseases (13 on AD) has also concluded that occupational exposure to pesticides increased the risk of AD (weighted relative risk (RR), 95% CI: 1.50, 0.98-2.29) [52]. A recent cohort data not included in the above meta-analysis came from the Hellenic Longitudinal Investigation of Aging and Diet study in Greece [53], which indicated an association between self-reported pesticide exposure and cognitive function [54].…”

The effects of 50 Hz magnetic field–exposed cell culture medium on cellular functions in FL cells

“…Based on limited epidemiological evidences, in 2002, the International Agency for Research on Cancer (IARC) classified ELF-MF as a possible carcinogen for humans [7]. In addition, some studies have indicated that ELF-MFs could contribute to the etiology of neurodegenerative disorders, in particular of Alzheimer’s disease (AD) and amyotrophic lateral sclerosis (ALS) [8].…”

Gut–Brain Axis: Potential Factors Involved in the Pathogenesis of Parkinson's Disease

“…The link between herbicide and paraquat exposure and neurotoxin MPTP administration and PD has suggested that environmental toxins can cause the disease. A recent metaanalysis from 31 studies with occupational exposure to pesticides suggested a significant association with PD risk (54). Rotenone has been reported to inhibit mitochondrial complex 1 activity, whereas paraquat causes oxidative stress (55)(56)(57)(58).…”