Long-Term Exposure to Chlorpyrifos Doubles Parkinson's Risk, Study Finds

A UCLA study links prolonged residential exposure to the pesticide chlorpyrifos with more than a 2.5-fold increase in Parkinson’s disease risk. The research identifies how the chemical disrupts cellular protein clearance, leading to neuron damage. These findings point to potential protective strategies against environmental triggers of neurodegeneration.

A 2026 UCLA study found that long-term residential exposure to chlorpyrifos, a widely used pesticide, is associated with more than a 2.5-fold increase in Parkinson’s disease risk among individuals who lived or worked in areas with documented applications of the chemical. The research analyzed data from 829 Parkinson’s patients and 824 controls enrolled in the university’s long-running Parkinson’s Environment and Genes study, cross-referencing California’s pesticide application records with participants’ historical residential and workplace addresses. Although chlorpyrifos was banned for residential use in the U.S. in 2001 and faced agricultural restrictions in 2021, it remains in use on many crops domestically and is still applied globally. The study’s findings are particularly significant given that Parkinson’s symptoms may appear decades after exposure, underscoring the long-term health consequences of environmental toxins. In lab models, chlorpyrifos-exposed mice developed motor impairments and lost dopamine-producing neurons—hallmarks of Parkinson’s—alongside brain inflammation and abnormal alpha-synuclein accumulation, a protein linked to disease progression. Zebrafish experiments further revealed that chlorpyrifos disrupts autophagy, the cellular process responsible for clearing damaged proteins, suggesting a direct biological mechanism behind neurodegeneration.

The research team at UCLA Health, led by scientists studying environmental influences on neurodegenerative d