An initial study in 2000 implicated exposure to pesticides as a possible risk factor in the development of Parkinson’s disease. Fourteen years later, we know even more about how these chemicals damage the brain.
In 2000, a meta-analysis linked confirmed and presumed pesticide exposure with increased risk of Parkinson’s. Subsequent work supported this connection, including a large 2006 study that followed patients for nine years. The patients exposed to pesticides had a 70% higher incidence of Parkinson’s when the study ended; the risk was the same for exposed farmers and exposed non-farmers, hence some other farm-related factor wasn’t to blame. The study didn’t report on specific toxins, but more recent work out of The Parkinson’s Institute in Sunnyvale, CA, founded by Langston after the MPTP discovery, did. The authors took detailed occupational and exposure histories from farmers and their families. Paraquat upped Parkinson’s risk 2.5-fold.