Case–control study of environmental risk factors for Parkinson's disease in Belgium

The aetiology of Parkinson's disease (PD) is unknown and said to be multifactorial. We report on a retrospective epidemiological case control study, performed in Flanders during a 3-year period, investigating known and potential environmental risk factors for PD by means of questionnaires. We investigated 423 prevalent patients and 205 spouse-controls. We found familial occurrence in 15% of the patients, a mean age of onset of 58 years, and a clear male preponderance (male/female ratio 1.53). Our results suggest more nulliparity among female PD patients (95% CI: 1.08–5.76). We found a discrete clustering of patients in areas with intensive metallurgic activity. Patients were more frequently employed in metallurgy than controls (95% CI: 1.04–9.20). Furthermore, patients were clearly more exposed to zinc (95% CI: 1.51–90.90) and toluene (95% CI: 1.03–58.82). Male patients report more prostatectomy-surgery (95% CI: 1.54–17.24).