) - In the first large-scale, prospective study to examine possible
links between chronic, low-dose exposure to pesticides and
Parkinson's disease ( PD ), researchers at the Harvard School of
Public Health ( HSPH ) have shown that individuals reporting
exposure to pesticides had a 70 percent higher incidence of
Parkinson's disease than those not reporting exposure. No increased
risk of Parkinson's disease was found from reported exposure to
other occupational hazards, including asbestos, coal or stone dust,
chemicals, acids, or solvents.
The study is published in the Annals of Neurology.

Previous studies had suggested a link between Parkinson's disease
and low-level exposure to pesticides, though the data remains
inconclusive. The researchers, led by Alberto Ascherio, at HSPH,
looked at data from the Cancer Prevention Study II Nutrition Cohort,
a prospective study begun in 1992 by the American Cancer Society.
Some 143,325 participants who responded to a follow-up survey in
2001 were included in the HSPH study. Researchers then contacted
those individuals in the 2001 survey who reported a diagnosis of
Parkinson's disease to ask if their medical records could be
reviewed to confirm the diagnosis. Ultimately, Ascherio and his
colleagues included in their study a total of 413 cases of
Parkinson's disease with onset of symptoms and diagnosis after 1992.

The researchers used exposure data collected in 1982 from the CPS II
mortality study, a study from which the Nutrition Cohort was drawn.
Exposure to pesticides was reported by 5,203 men ( 8.2 percent ) and
2,661 women ( 3.3 percent ). Among those reporting exposure, after
adjusting for age, sex, and other risk factors for Parkinson's
disease, there was a 70 percent higher incidence of Parkinson's
disease than among people who reported no exposure. Those reporting
exposure were more likely to be male than female to report their
occupation as farmer, rancher or fisherman and to be blue-collar
workers, but none of these factors could account for the increased
risk of Parkinson's disease, which was similar in men or women, and
in non-farmers as well as farmers. The significant association
between pesticide exposure and Parkinson's disease among individuals
who are not farmers is most likely explained by use of pesticides at
home or in gardening.

Future studies will need to examine which specific pesticides or
classes of pesticides are likely to cause Parkinson's disease.


12/27/06(Harvard School of Public Health