Chlorpyrifos exposure associated with higher Parkinson’s disease risk

Researchers analyzed 829 people with Parkinson’s disease and 824 controls enrolled in UCLA’s Parkinson’s Environment and Genes study. They combined participants’ residential and workplace histories with California pesticide-application records to estimate chlorpyrifos exposure. The main human finding was that prolonged residential exposure was associated with more than 2.5 times the risk of Parkinson’s disease compared with no recorded exposure; the report provides no confidence interval or other effect estimate details.

In experiments, mice exposed to chlorpyrifos aerosol for 11 weeks developed movement difficulties, dopamine-producing neuron loss, brain inflammation and alpha-synuclein accumulation. Zebrafish experiments implicated disrupted autophagy, the cellular process that removes damaged material. Restoring this process or removing synuclein protected neurons in the laboratory models.

The findings support further investigation of a possible link and biological pathway, but the human analysis is observational and cannot show that chlorpyrifos caused disease. Protective effects were demonstrated only in laboratory models, not in people. The study does not establish a clinical monitoring strategy or treatment. The source notes that residential use of chlorpyrifos was banned in the United States in 2001, with additional restrictions on agricultural use in 2021.