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PDF Interprets: Pesticides and Parkinson's in the Workplace

People who use certain chemicals as part of their job may be at an increased risk for Parkinson’s disease (PD), according to a report in the September issue of Archives of Neurology

Lead investigator Caroline Tanner, M.D., Ph.D., of the Parkinson’s Institute and her colleagues, conducted a nationwide study of occupation, chemical use, and risk of Parkinson’s disease.  They asked the question: do some occupations and the chemicals they employ carry more risk than others for the development of Parkinson’s disease?

Evidence has continued to accumulate demonstrating that environmental risk factors may play a role in Parkinson’s disease, either acting as a trigger for inherited mechanisms, or causing the disease pathology independently.  Exposure to industrial and agricultural chemicals has been proposed as a risk factor, thus occupations that involve chronic contact with chemicals may significantly increase the risk of developing Parkinson’s disease. 

In the study, Dr. Tanner and colleagues surveyed 519 people with Parkinson’s and 511 control subjects from around the country about their work history, including the kind of chemicals they were exposed to in their jobs. 

They found that occupations that had previously been proposed as increasing the risk of Parkinson’s disease, such as farming and welding, did not show up as significant risk factors.  In fact, no specific occupations were associated with increased incidence of Parkinson’s disease.  However, the research team found that regardless of occupation, use of pesticides was associated with a nearly 80 percent higher risk of Parkinsonism.  Three pesticides in particular were identified with a particularly high risk increase: the insecticide permethrin, and the herbicides paraquat and 2,4-dichlorophenoxyacetic acid all increased the risk of Parkinson’s by more than three times. 

Paraquat has previously been associated with Parkinson’s disease.  The associations with permethrin and 2,4-dichlorophenoxyacetic acid, however, are new, and are notable in part for how commonly these chemicals are used.  Permethrin, for instance, is used as an antimalarial treatment for fabrics and mosquito netting, and 2,4-dichlorophenoxyacetic acid is among the most commonly used agricultural herbicides in the world.

Although these pesticides are in wide use, the study’s authors emphasize that the study was concerned only with occupational exposure.  The risk carried by other routes of contact, like gardening or wearing permethrin-treated garments, is unknown, but in the words of the authors, “Because these exposures may affect many more subjects, future attention is warranted.”


Source Date: Sep 22 2009