UCLA Health study: chlorpyrifos linked to Parkinson's disease risk

UCLA Health specialists analyzed data from participants in the Parkinson's Environment and Genes study. By comparing information on 829 Parkinson's disease patients and 824 individuals without this diagnosis with California pesticide use records and address histories, the researchers established a link between the disease and prolonged residence in areas exposed to chlorpyrifos.

In laboratory experiments, mice that inhaled chlorpyrifos aerosol for 11 weeks experienced movement difficulties, brain inflammation, and the loss of dopamine-producing neurons, as well as the accumulation of alpha-synuclein protein. Experiments on zebrafish showed that the chemical disrupts autophagy—the natural cellular clearance of damaged proteins. When the researchers restored this mechanism or removed synuclein, the neurons were protected from damage.

Chlorpyrifos has been used in agriculture for decades. In the US, its residential use was banned in 2001, and in 2021 additional restrictions were introduced on agricultural application, yet the pesticide is still used for treating many crops in the US and other countries.

According to senior study author Dr. Jeff Bronstein, professor of neurology at UCLA Health, the work establishes chlorpyrifos as a specific environmental risk factor for Parkinson's disease rather than pesticides as a general class, and the demonstration of the neurotoxicity mechanism points to potential therapeutic strategies.