A recent study by researchers at the Harvard School of Public Health in Boston, MA examined the relationship between Parkinson's Disease and pesticide use in over 143,000 individuals who participated in the Cancer Prevention Study II Nutrition Cohort. The study covered the 10-year period from 1992 to 2001.
Exposure to pesticides was reported by 7,864 participants (5.7%), including 1,956 farmers, ranchers, or fishermen. People reporting exposure to pesticides were found to have a 70 percent higher incidence of Parkinson's than those without exposure.
There was no increased risk of Parkinson's disease associated with exposure to asbestos, chemicals/acids/solvents, coal or stone dust, or eight other occupational exposures that are known to cause other health problems.
Parkinson's disease may have developed 5 to 20 or more years after exposure to pesticides. Exposure for the non-farmers, ranchers and fishermen may have occurred by household use of bug sprays, lawn sprays or fumigants. The most commonly used termite fumigant, Vikane (sulfuryl flouride), lists the result of overexposure as poor coordination, slurring words and confusion, all potential neurological symptoms.
From a study on nervous system health noted below, Tocotrienols, a form of vitamin E, may help maintain the health of the nervous system, explaining the inconsistent results of previous Parkinson's studies and drawing attention to this least studied form of vitamin E. The researchers concluded, “it is prudent to conclude that orally supplemented alpha-tocotrienol may protect neurons from toxic insults.”
OBJECTIVE: Chronic, low-dose exposure to pesticides is suspected to increase the risk for Parkinson's disease (PD), but data are inconclusive. METHODS: We prospectively examined whether individuals exposed to pesticides have higher risk for PD than those not exposed. The study population comprised participants in the Cancer Prevention Study II Nutrition Cohort, a longitudinal investigation of US men and women initiated in 1992 by the American Cancer Society. Follow-up surveys were conducted in 1997, 1999, and 2001. The 143,325 individuals who returned the 2001 survey and did not have a diagnosis or symptoms of PD at baseline (1992) were included in the analyses. RESULTS: Exposure to pesticides was reported by 7,864 participants (5.7%), including 1,956 farmers, ranchers, or fishermen. Individuals exposed to pesticides had a 70% higher incidence of PD than those not exposed (adjusted relative risk, 1.7; 95% confidence interval, 1.2-2.3; p = 0.002). The relative risk for pesticide exposure was similar in farmers and non-farmers. No relation was found between risk for PD and exposure to asbestos, chemical/acids/solvents, coal or stone dust, or eight other occupational exposures. INTERPRETATION: These data support the hypothesis that exposure to pesticides may increase risk for PD. Future studies should seek to identify the specific chemicals responsible for this association.
Ascherio A, Chen H, Weisskopf MG, O'Reilly E, McCullough ML, Calle EE, Schwarzschild MA, Thun MJ. Pesticide exposure and risk for Parkinson's disease. Ann Neurol. 2006 Aug;60(2):197-203.