The fertile soil of Californiaâ€™s Central Valley has long made it famous as the nationâ€™s breadbasket. But itâ€™s not just the soil that allows for such productivity. Crops like potatoes, dry beans, and tomatoes have long been protected from bugs and weeds by the fungicide maneb and the herbicide paraquat.
Scientists know that in animal models and cell cultures, such pesticides trigger a neurodegenerative process that leads to Parkinsonâ€™s disease. Now scientists at UCLA provide the first evidence for a similar process in humans.
In a new epidemiological study of Central Valley residents who had been diagnosed with Parkinsonâ€™s disease (PD), it was found that years of exposure to the combination of these two pesticides had increased the risk of PD by 75 percent.
Further, for people 60 years old and younger diagnosed with PD, earlier exposure had increased their risk to the disease by as much as four-to-six-fold.
Reporting in the current issue of the American Journal of Epidemiology, senior author Beate Ritz, professor of epidemiology at the UCLA School of Public Health, and first author Sadie Costello, a former doctoral student at UCLA, now at the University of California, Berkeley, found that Valley residents who lived within 500 meters of fields sprayed between the years of 1974-1999 had a 75 percent increased risk to Parkinsonâ€™s.
Further, people who were diagnosed with Parkinson’s Disease at age 60 or younger were found to have been at much higher risk because they had been exposed to either maneb or paraquat alone or to both pesticides in combination, between the years 1974â€“1989, a time when they would have been children, teens, or young adults.