ADDRESSING THE ROLE OF OCCUPATIONAL EXPOSOME ON PARKINSON’S DISEASE AND PARKINSONISM IN A MATCHED CASE-CONTROL STUDY

Background/Objectives Occupational exposure to neurotoxicants such as pesticides, metals, and solvents has long been implicated in Parkinson’s disease (PD) and Parkinsonism, yet the cumulative impact of multiple occupational exposure families over the working life remains insufficiently characterized. This study evaluated whether long-term cumulative occupational exposures, derived from the ALOHA+ Job-Exposure Matrix (ALOHA+-JEM), were associated with PD and Parkinsonism. Methods A hospital-based matched case–control study was conducted in the province of Brescia, Italy, including 668 participants (334 PD/Parkinsonism cases and 334 matched controls). Cases and controls were 1:1 matched based on sex, age, and lifetime occupational duration. Lifetime occupational histories were coded using ISCO-08 and harmonized to ISCO-88 for linkage with ALOHA+-JEM. Conditional logistic regression estimated associations between cumulative exposures (none/low/high) and disease status, adjusting for smoking, parental history of PD/tremor, and SNCA rs356219 genotype. Multi-agent occupational exposure burden indexes were evaluated using positively constrained repeated-holdout Weighted Quantile Sum (WQS) regression (100 bootstraps, 100 holdouts) Results In conditional logistic regression, parental history of PD or tremor (OR = 4.55, 95% CI: 2.44–8.48; q < 0.001) and the SNCA rs356219 CC genotype (OR = 2.17, 95% CI: 1.33–3.52; q = 0.013) were significantly associated with disease. High cumulative all pesticide exposure showed positive associations with combined PD + Parkinsonism (OR = 2.98, 95% CI: 1.23–7.25) and PD alone (OR = 3.56, 95% CI: 1.25–10.15). In WQS analyses, the composite occupational exposure burden index was positively associated with disease (combined PD + Parkinsonism: OR = 1.15, 95% CI: 1.00–1.30). All pesticides received the highest mean weight in all models (w = 0.434 for combined PD + Parkinsonism), followed by metals (w = 0.210), identifying them as contributing most strongly to the composite exposure index. Conclusions Long-term cumulative occupational exposures were associated with increased odds of PD and Parkinsonism. All pesticides and metals were most strongly associated with PD and Parkinsonism, consistent with established neurotoxic mechanisms attributable to occupational environments. These findings underscore the importance of occupational exposure prevention and risk-reduction strategies in occupational settings and highlight workplace exposures as preventable contributors to Parkinsonian disorders.