Harvard Study Strengthens Link between Parkinson’s and Pesticides

By Daniel Hawn

Published on December 28, 2006

The Harvard study, published in the Annals of Neurology, provides the clearest correlation to date between pesticides and Parkinson’s, though data are still inconclusive.

Led by Alberto Ascherio, Harvard researchers used data from a 1992 American Cancer Society lifestyle study in which over 143,000 participants responded to a 2001 follow-up survey. The Harvard study ultimately included 413 cases of Parkinson's diagnosed after 1992.

Individuals who reported exposure to pesticides had a 70 percent greater incidence of Parkinson’s than those who reported no exposure. The increased incidence occurred regardless of whether the exposure was work related or not, implying that home-use of pesticides, such as in gardening, is just as risky as use by farmers and ranchers.

While the exact cause of Parkinson’s is as yet unknown, decreased dopamine production in the brain accounts for many of the symptoms of Parkinson’s, including muscle tremors and rigidity.

Future studies will need to examine which pesticide chemical compounds adversely affect the brain and its ability to produce dopamine.

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