Exposure to certain chemicals found in pesticides and herbicides may increase the risk of Parkinson’s disease in people with a family history of the disease, according to a new study.

Researchers say the findings support evidence of a possible link between environmental toxins and Parkinson’s disease and may help explain why some people with genetic risk factors for the disease get it while others do not.

Parkinson’s disease is a common neurological disorder that can occur randomly or as the result of inherited gene mutations.

In the study, which appears in Current Biology, researchers looked at fruit flies lacking both forms of a gene that is associated with the inherited form of Parkinson’s disease. These specially bred fruit flies became extremely sensitive to the herbicide paraquat and the insecticide rotenone and died after exposure.

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New Proof of Environmental Link to Parkinson’s Disease

Researchers based their study on previous findings that show exposure to environmental toxins may raise the risk of developing the disease by increasing the rate of oxidative stress. Oxidative stress is related to the body’s ability to eliminate free radicals in the body and can result in cell damage within the body.

In the study, researchers showed that flies lacking forms of the DJ-1 gene were normal under standard conditions. But when they were exposed to high doses of the herbicide paraquat and insecticide rotenone, which have previously been linked to Parkinson’s disease, the flies suffered from extreme oxidative stress and died.

Researchers say these findings suggest that a loss of DJ-1 gene function increases sensitivity to chemicals that cause oxidative stress.

Together, researchers say the results shed new light on the biological connections between the inherited and sporadic forms of Parkinson’s disease and may lead to more effective treatments.

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By Jennifer Warner, reviewed by Louise Chang, MD

SOURCES: Meulener, M. Current Biology, Sept. 6, 2005; vol 15: pp 1572-1577. News release, Cell Press.