Researchers from the School of Civil and Environmental Engineering at Georgia Institute of Technology in Atlanta studied the cadavers of 14 Parkinson's patients and 12 similarly aged patients without the disease and found that levels of dieldrin -- an organochlorine pesticide -- were more than three times higher in the Parkinson's patients' brain tissue.
"We can't say at this point that pesticides cause Parkinson's disease, but we feel it accelerates the process," says researcher Kurt Pennell, an associate professor at Georgia Institute of Technology.
Pennell and his research group also exposed mice to low-level doses of dieldrin to simulate typical human exposure to the chemical, and found that the mice's brain tissue showed significant reduction in the uptake of the neurotransmitter dopamine, as well as increased levels of carbonyls -- indicators of oxidative stress.
"Our research shows that elevated levels of dieldrin are associated with Parkinson's disease in humans, which is supported by an animal model study that correlates low-level exposure to dieldrin with early markers of Parkinson's disease," Pennell says.
Though dieldrin was banned in 1987, Pennell says the chemical pesticide still persists in the ground and eventually accumulates in the body's fatty tissues, which include the brain. Researcher Gary Miller says levels of dieldrin in the ground are much lower today than they were 30 to 40 years ago, and that cases of Parkinson's could be similarly lower in the next few decades.