Reporting in the April 15 issue of the American Journal of Epidemiology, Beate Ritz, Professor of Epidemiology at UCLA and colleagues found that Central Valley residents who lived within 500 metres of fields sprayed between 1974 and 1999 had a 75% increased risk for Parkinson's.
In addition, people who were diagnosed with Parkinson's at age 60 or younger were found to have been at much higher risk because they had been exposed to maneb, paraquat or both in combination between 1974 and 1989, years when they would have been children, teens or young adults.
The results confirmed previous observations from animal studies that exposure to multiple chemicals may increase the effect of each chemical (which is important as humans are often exposed to more than one pesticide in the environment) and that the timing of exposure is also important.
The researchers noted that this is the first epidemiological study to provide strong evidence that maneb and paraquat act synergistically to become neurotoxic and strongly increase the risk of Parkinson's disease in humans. Of particular concern, and consistent with other theories regarding the progression of Parkinson's pathology, is that the data suggests that the critical window of exposure to toxicants may have occurred years before the onset of motor symptoms when a diagnosis of Parkinson's is made.
The researchers had enrolled 368 longtime residents diagnosed with Parkinson's and 341 others as a control group.
Courtesy of PAN UK www.pan-uk.org
First Published in 2009
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