This article was originally published back in 2006 by Harvard.
Individuals reporting exposure to pesticides had a 70% higher incidence of Parkinson's (PD) than those not reporting exposure. On a positive note, no increased risk of PD was found from exposure to other occupational hazards, such as: asbestos, coal dust, chemicals, or acids.
Taken from the article:
"Exposure to pesticides was reported by 5,203 men (8.2 percent) and 2,661 women (3.3 percent). Among those reporting exposure, after adjusting for age, sex, and other risk factors for Parkinson's disease, there was a 70 percent higher incidence of PD than among people who reported no exposure."
Exposure to these pesticides were more often found in males who's occupation was either a farmer or rancher. However, the data indicated regardless of occupations, the risk of PD was the same across the board. It is likely the others included in this study were exposed while at home or gardening.
As always, I encourage people to research these topics on their own, encourage feedback or comments. The study appeared in the July issue of Annals of Neurology (Ann Neurol. 2006; 60:197-203).