O2D.5 Risk of parkinson disease in solvent exposed workers in finland

Epidemiologic studies indicate that occupational exposure to solvents may increase risk of Parkinson disease (PD). We constructed a population-based case-control study of incident PD using a register of Reimbursement of medicine costs of the Social Insurance Institution of Finland, along with the Population Information System, including census records for all Finnish residents. PD cases were diagnosed between 1995–2014. Controls were randomly selected from the population while matching on diagnosis year, birth year (1930–1950), and sex. A total of 11,757 PD cases and 23 236 controls had data from the occupational census in 1990, ensuring ≥4 years exposure lagging and 21 years of occupational history data (5 censuses from 1970–1990). We used the Finnish Job Exposure Matrix to assess cumulative exposure (CE) to four groups of solvents (aliphatic/alicyclic hydrocarbon, aromatic hydrocarbon, chlorinated hydrocarbon, other). We estimated PD-solvent odds ratios (ORs) and 95% confidence intervals (CIs) using unconditional logistic regression, while adjusting for age, sex, socioeconomic status and smoking (a_OR), or additionally for CE to chromium and one of the other solvent groups (ab_OR). In total, 3758 cases (30.4%) and 7445 controls (32.0%) were potentially exposed to solvents (a_OR 0.99; CI: 0.94–1.05). Exposure to chlorinated hydrocarbons was associated with PD (a_OR 1.20; CI: 1.05–1.36; ab_OR 1.21 CI: 1.04–1.40) at the highest CE group (20–145 ppm-years, n=409 cases and 728 controls) but not at lower CE levels. Overall, CE to chlorinated hydrocarbons (n=1840 cases and 3693 controls) was associated with increased risk of PD (p-for-trend=0.01). There was no evidence of a positive association for any of the other solvent groups. We observed a positive association between occupational exposure to chlorinated hydrocarbons and risk of PD. This was especially true for greatest duration and/or level of exposure.