(Beyond Pesticides, April 24, 2007) Three recent studies were presented earlier this month at the Parkinsonâ€™s Disease Environmental Research meeting in California strengthening the theory that pesticides increase risk of the disease. The studies clarify how pesticide exposure can lead to the development of Parkinsonâ€™s.
Two pesticides named in the studies are paraquat and dieldrin, both of which have been linked to Parkinsonâ€™s in the past. The three new studies, however, combine information from human and animal studies to show how exposure can lead to onset of the disease. As William Langston, M.D., founder of the Parkinsonâ€™s Institute, told Reuters, â€śAll of these pieces really look like they are coming together now.”
The first study examined a cohort of 80,000 licensed private pesticide applicators and spouses. Researchers found farm workers exposed to paraquat had twice the expected risk of Parkinsonâ€™s.
The second and third studies address a protein called alpha-synuclein. The second study shows the protein builds up in rodents exposed to paraquat. The third study connects this protein to Parkinsonâ€™s by finding that the protein kills the dopamine-producing brain cells affected by the disease.
One common difficulty in tracking pesticide-induced diseases is the amount of time that passes between exposure and the onset of disease. In these studies, pesticide exposure could be accurately tracked by records of pesticide purchase, details of which will be published later, according to Dr. Langston.
The study of laboratory animals could be the missing link in proving causation of Parkinsonâ€™s. Donato Di Monte, M.D., of the Parkinsonâ€™s Institute, said of the protein buildup, â€śThis increase in alpha-synuclein in the brain could be the missing link between the exposure to this agent and how this agent causes the disease.” In addition, Dr. Langston said brain inflammation during pesticide exposure greatly increased the risk of Parkinsonâ€™s in later years, as â€śsystemic inflammation may somehow sensitize the brain.”
These studies are only the latest linking pesticides, particularly paraquat, to Parkinsonâ€™s disease. For previous Daily News stories on the subject (and other health effects), click here.