(Beyond Pesticides, January 11, 2010) Yet another study has been published that further supports the causative link between pesticide exposure and Parkinson’s disease. The study, funded by the National Institute of Environmental Health Sciences (NIEHS), is published in the January issue of Epidemiology. The University of California, Los Angeles researchers looked at the association between Parkinson’s disease, organophosphate pesticides and the common gene variant, paraoxonase-1 gene Leu-Met 55 polymorphism (PON1-55 MM). The findings show that study participants with two copies of gene variant have a significantly increased risk of developing Parkinson’s disease when exposed to certain organophosphate pesticides used in agriculture.
The population-based case-control study examined the DNA of 351 incident cases and 363 controls from three rural counties in California. The researchers then used pesticide usage reports and a geographic information system (GIS) approach to determine the study participants’ residential exposure to organophosphates. The PON1 gene codes for an enzyme that metabolizes organophosphate pesticides.
Individuals with the variant MM PONI1-55 genotype that are exposed to organophosphates exhibit more than twice the risk of Parkinson’s disease compared to carriers of wildtype or heterozygous genotype and no exposure. In regards to exposure to diazinon, carriers of variant MM PONI-55 genotype show a 2.2 increase in risk of Parkinson’s disease; and exposure to chlorpyrifos show a 2.6 increase in risk of the disease. For younger-onset cases and controls (less than or equal to 60 years), the study finds a 5.3-fold increase in risk for chlorpyrifos exposure.
“Our research suggests that the impact of organophosphate exposure depends on the activity of a detoxifying enzyme produced by the body,” stated Beate Ritz, M.D., Ph.D., co-author of the study, in the NIEHS Environmental Factor.
The second most common neurodegenerative disease, Parkinson’s, occurs when nerve cells in the substantia nigra region of the brain are damaged or destroyed and can no longer produce dopamine, a nerve-signaling molecule that helps control muscle movement. People with Parkinson’s have a variety of symptoms including loss of muscle control, trembling and lack of coordination.
Previous studies have linked pesticide exposure to the onset of Parkinson’s disease, including several published in the last year alone.
For more on Parkinson’s disease, please read “Pesticides Trigger Parkinson’s Disease,” a review of published toxicological and epidemiological studies that link exposure to pesticides, as well as gene-pesticide interactions, to Parkinson’s disease and published in Pesticides and You (Spring 2008).
Support organic farming and protect farmers, farmworkers, and their families and neighbors from toxic chemicals. Organic agriculture does not allow the use toxic chemicals that have been shown to cause a myriad of chronic health effects, such as cancer, endocrine disruption and a series of degenerative diseases like Parkinson’s disease. For more information of the many benefits of organic food, please visit Beyond Pesticides’ Organic Food program page.