With summer in full swing, many green-thumbs are donning their gloves and taking spade, bug-and weed-killer in hand to do some serious gardening.But the findings of a new study from the Harvard School of Public Health (HSPH) published in the July issue of Annals of Neurology may is worth considering first.

In the first large-scale prospective study to look at the link between chronic, low-dose exposure to pesticides and Parkinson’s disease, researchers showed that individuals who reported exposure to pesticides had a 70% higher incidence of Parkinson’s disease than those who did not, after adjusting for age, sex, smoking and potential risk factors. Parkinson’s disease is a progressive condition that affects the nerve cells in the part of the brain that controls movement.

Participants were drawn for the HSPH study from the Cancer Prevention Study II Nutrition Cohort, started in 1992 by the American Cancer Society, if they responded to the 2001 follow-up survey. (The exposure data was taken from information gathered in 1982 during a related study.) Of the 143,325 participants, about 8% (5,203 people) reported exposure to pesticides and they were more likely to be male and report their occupation as farmer, rancher, fisherman or blue-collar worker than those who reported no exposure. Ten to 20 years after exposure, 413 cases of Parkinson’s disease were identified.

What it means: Exposure to pesticides and herbicides in the garden, while limited, is still something to consider. Non-toxic alternatives to common pesticides are increasingly popular and a variety are on the market, either in garden shops or online.

This study supports on a larger scale what other studies have found: a correlation between pesticide and herbicide exposure and increased risk of Parkinson’s disease. Certain compounds in pesticides are believed to cause oxidative stress, cellular dysfunction, inflammation and adversely affect dopamine levels, but the relation of these mechanisms to Parkinson’s has yet to be clearly understood. Exposure to pesticides could also indicate other aspect of rural living not accounted for in the study, but there is strong evidence from previous studies to back the current findings. The study does not, however, specify the kinds of pesticides that might trigger mechanisms that lead to Parkinson’s, an objective that the researchers pose to future studies. They suggest that attempts to reduce overall exposure to pesticides, to avoid being at higher risk of the disease, might be "insufficient and impractical".

From the archives:
06/12/06 The Grass-Fed Revolution
04/17/06 The Green Home