Common Pesticide Linked to More Than Double the Risk of Parkinson's Disease
A UCLA Health study finds that long-term exposure to the agricultural pesticide chlorpyrifos near the home is associated with a more than 2.5-fold increase in Parkinson's disease risk. Laboratory experiments revealed the pesticide damages dopamine-producing neurons and disrupts the cell's autophagy process.
Study Highlights Pesticide Risk
Researchers at UCLA Health have reported that long-term residential exposure to chlorpyrifos, a widely used agricultural pesticide, is linked to a more than 2.5-fold increased risk of developing Parkinson's disease. The study, published in Molecular Neurodegeneration, combined data from hundreds of people with laboratory experiments to uncover the biological mechanism.
Parkinson's disease is a progressive neurological disorder affecting nearly one million Americans. It occurs when dopamine-producing brain cells gradually die, leading to tremors, stiffness, and balance problems.
Chlorpyrifos Usage
Chlorpyrifos has been used on crops for decades. Residential uses were banned in 2001, and agricultural restrictions were introduced in 2021, but the chemical remains in use in the U.S. and many other countries.
Data Analysis and Findings
The team analyzed data from 829 Parkinson's patients and 824 controls enrolled in UCLA's ongoing Parkinson's Environment and Genes study. By combining California pesticide application records with residential and workplace addresses, they estimated each participant's long-term exposure. Those with higher residential exposure had more than 2.5 times the risk of Parkinson's.
Laboratory Experiments
To understand why, researchers exposed mice to aerosolized chlorpyrifos via inhalation for 11 weeks, mimicking human exposure. The mice developed movement problems, lost dopamine-producing neurons, showed brain inflammation, and accumulated alpha-synuclein, a protein associated with Parkinson's.
Further experiments in zebrafish revealed that chlorpyrifos disrupts autophagy, the cell's internal cleanup system. When autophagy was restored or synuclein was removed, nerve cells were protected.
Implications and Future Research
Senior author Dr. Jeff Bronstein, professor of Neurology at UCLA Health, stated that the study establishes chlorpyrifos as a specific environmental risk factor for Parkinson's, not just pesticides in general. The discovery of autophagy dysfunction points to potential therapeutic strategies. Future studies will explore whether other pesticides act similarly and whether treatments that enhance autophagy could reduce Parkinson's risk among exposed individuals.
