Correlation between decreased cognitive performance and increased pesticide exposure. Furthermore, the decrease in cognitive performance was “striking,” they said, given the “short duration of the follow-up and the relatively young age of the participants.”

8 Mar

Pesticides and Dementia - The Link

© AFP/Jacques Demarthon

Rose Sneyd summarizes a study into the effects of exposure to pesticides on French vineyard workers.
Posted Monday, 11-Jun-2012

A Bordeaux-based study on the cognitive performance of vineyard workers reveals a correlation between prolonged exposure to pesticides and a heightened risk of developing Alzheimer’s disease or other forms of dementia.

The study, entitled Phytoner, is the work of the Laboratoire Santé Travail Environnement at the University of Bordeaux Segalen. It was launched in the late-1990s with the recruitment of 929 subjects in south-west France. Participants had to have worked in agriculture for at least 20 years, including a minimum of 1000 hours in 1995, and to be aged between 40 and 55 years.

On enrolment, the workers sat nine neurobehavioral tests. Of this initial group, 614 completed the follow-up, which involved another battery of tests between 2001 and 2003.

All candidates were categorized according to their level of exposure to pesticides, based upon the nature of their jobs. Those considered to have been directly exposed had mixed or applied pesticides in vineyards or cleaned or repaired spraying equipment. Those who had been indirectly exposed had either worked in contact with treated plants or had worked in a vineyard. There was also a category for those who had not been exposed to pesticides.

While the subjects’ pesticide exposure was codified, the specific pesticides with which they worked were not identified in the Phytoner study, for two reasons. Firstly, the participants were unaware which pesticides they were using and, secondly, wine production involves an arsenal of different substances, particularly against various fungi.

However, the researchers deduced that the pesticides of “primary concern” were those used during the 1970s and 80s. These included fungicides (dithiocarbamates, phtalimides, dicarboximides, triazoles and inorganic substances such as copper, sulphate and arsenic), insecticides (organophosphates, organochlorines and carbamates) and some herbicides (triazines or sulfamides).

Once the participants had completed the follow-up, the difference between their performance on enrolment (1997–98) and at the second stage (2001–03) was compared according to their exposure to pesticides.

The first phase of the study showed that workers directly exposed to pesticides performed worse in the neurobehavioral tests than those indirectly exposed. The follow-up confirmed this finding.

Importantly, when the exposed workers were compared with the non-exposed workers in the follow-up, the difference in performance was statistically significant in all tests except one (the Wechsler Similarities Test), and the “increase in risk was seen in both directly and indirectly exposed subjects,” the researchers reported.

In addition, those participants whose scores showed the most significant decreases “were more frequently exposed subjects” – except in two of the tests (the Wechsler Similarities Test and the Wechsler Paired Test).

These results led the researchers to conclude that there was a correlation between decreased cognitive performance and increased pesticide exposure. Furthermore, the decrease in cognitive performance was “striking,” they said, given the “short duration of the follow-up and the relatively young age of the participants.”

The study’s authors also noted that their findings were consistent with previous studies on the cognitive effects of chronic pesticide exposure on farm workers.

To read the full article, published in “Occupational and Environmental Medicine,” click here.

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