LOS ANGELES, May 26 (UPI) -- Combined exposure to three pesticides near any workplace increased Parkinson's disease risk three-fold in California's Central Valley, researchers say.
Senior author Beate Ritz, a professor of epidemiology at the University of California, Los Angeles, School of Public Health, and colleagues said the combined exposure to ziram, maneb and paraquat near any workplace increased the risk of Parkinson's disease three-fold.
However, the combined exposure to ziram and paraquat alone was associated with an 80 percent increase in risk.
"Our estimates of risk for ambient exposure in the workplaces were actually greater than for exposure at residences," Ritz said in a statement. "And, of course, people who both live and work near these fields experience the greatest Parkinson's disease risk. These workplace results give us independent confirmation of our earlier work that focused only on residences, and of the damage these chemicals are doing."
The study provides strong evidence that the combination of the three chemicals confers a greater risk of Parkinson's than exposure to the individual chemicals alone, Ritz said.
The findings appear in the current online edition of the European Journal of Epidemiology.