Every year, 50,000 Americans are diagnosed with Parkinson's disease. Less than 5 percent of these cases can be traced to genetic predisposition.

So what's causing the rest? Pesticides may be one culprit, according to a recent study. Research conducted at Rutgers University showed that male mice exposed to the commonly used fungicide maneb before birth, then to the herbicide paraquat as adults, sustained considerable damage to dopamine-producing cells and lost 90 percent of their motor function (Environmental Health Perspectives, 2005, vol. 113, no. 9). Neither chemical had this effect without exposure to the other, a concern because the U.S. Environmental Protection Agency does not test pesticides together for safety.

"[These chemicals] are in the food you eat, the water you drink, and the air you breathe," says lead author Deborah Cory-Slechta, PhD. "The less you're exposed, the better." To minimize ingesting pesticides in food, wash fruits and vegetables thoroughly, she suggests. And buy organic as often as possible. If you have a lawn or garden, cut down or avoid pesticide use altogether by opting for nontoxic gardening solutions.