More Evidence for Parkinson’s Disease and Pesticide Link

Michael A. Schwarzschild, MD, Ph.D.
Department of Neurology, Massachusetts General Hospital
R01ES10804

A large epidemiologic study shows that individuals reporting regular exposure to pesticides had a 70 percent higher incidence of Parkinson’s disease than those reporting no exposure. The study, funded by NIEHS and conducted by researchers at the Harvard School of Public Health, is the first large­scale prospective study to examine the possible links between chronic pesticide exposure and Parkinson’s disease.

Previous studies suggested pesticide exposure as a risk factor for the dreaded neurological disorder; however, the results were inconclusive probably because of the relatively small number of participants. The current study included more than 143,000 subjects; 7,800 reported exposure to pesticides. No increased risk for Parkinson’s disease was found from other occupational hazards including exposure to other chemicals or solvents.

Research utilizing twins has established that genetics probably plays a minor role in Parkinson’s disease and thus has made environmental exposures the focus of much interest. A compound known as MPTP, a by­product of the production of a heroin­like illicit drug and structurally similar to the herbicide paraquat, causes death of neurons in the substantia nigra, the part of the brain affected by Parkinsons’s disease. For that reason pesticides and herbicides exposures are considered likely to cause or contribute to the development of Parkinson’s disease.

Citation: Ascherio A, Chen H, Weisskopf MG, O'reilly E, McCullough ML, Calle EE, Schwarzschild MA, Thun MJ. Pesticide exposure and risk for Parkinson's disease. Ann Neurol. 2006 Jun 26; [Epub ahead of print]