Long-Term Exposure to Pesticides May Raise Dementia Risk

Long term exposure to pesticides may be linked to the development of dementia.  Isabelle Baldi, from the Institut de Sante Publique d'Epidemiologie et de Developpement (France), and colleagues studied 614 vineyard workers in South West France whose intellectual capacity was monitored for up to six years as part of the PHYTONER study.  The team categorized the subjects’ levels of exposure to pesticides based on job calendars, identifying each as 'directly exposed' (mixing or applying pesticides, cleaning or repairing spraying equipment); 'certainly indirectly exposed' (contact with treated plants); 'possibly indirectly exposed' (work in buildings, offices, cellars); and 'not exposed' if they had done none of the above.  Just under 1,000 workers enrolled in the study between 1997 and 1998, 614 of whom were monitored between 2001 and 2003. On both occasions they completed a questionnaire and nine neurobehavioral tests designed to measure memory and recall; language retrieval and verbal skills; and reaction time speeds.  One in five had never been exposed to pesticides as part of their job; over half had been directly exposed, and the remainder had been possibly or certainly indirectly exposed.  With the exception of two of the nine tests, those who had been exposed to pesticides were the most likely to perform worse second time around.  These workers were up to five times as likely to obtain lower test scores on both occasions, and they were twice as likely to register a drop of two points in the mini mental state exam (MMSE). Concluding that: “These results suggest long-term cognitive effects of chronic exposure to pesticides and raise the issue of the risk of evolution towards dementia,” the team submits that: “The PHYTONER study is the first to provide prospective data on the natural history of neurological disorders associated with pesticide exposure.”