Occupational Manganese Exposure and Risk of Parkinson's Disease: A Systematic Review and Meta-Analysis

Background

Parkinson’s disease (PD) is a progressive neurodegenerative disorder characterized by impaired voluntary motor control and is the fastest-growing neurological disorder worldwide in terms of prevalence. Although the etiology of PD remains unclear, environmental and occupational neurotoxicants may contribute to disease development. Manganese (Mn) has received increasing attention as it can accumulate in the brain and disrupt motor function with chronic overexposure leading to neurotoxicity. However, the association between occupational Mn exposure and clinically diagnosed PD has not been comprehensively evaluated. This systematic review and meta-analysis assessed whether occupational Mn exposure is associated with PD risk.

Methods

PubMed and Web of Science were systematically searched from database inception to January 19, 2026. Two reviewers independently screened studies and extracted data. Summary effect estimates were calculated using a random-effects meta-analysis.

Results

Eighteen studies were included. After adjusting for publication bias using the trim-and-fill method, the summary effect estimate was 0.89 (95% CI: 0.85-0.93; p<0.001) suggesting no increased PD risk with occupational Mn exposure. Heterogeneity was low (I² = 0%). Findings were consistent across study designs in subgroup analyses but differed by exposure assessment method with industrial hygiene-based measures suggesting a potential elevated PD risk. Sensitivity analyses confirmed the robustness of results.

Conclusion

This meta-analysis does not support a positive association between occupational Mn exposure and PD. Additional longitudinal studies with improved exposure assessment are needed to further clarify this relationship.