Researchers at the University of California, Los Angeles (UCLA) have demonstrated a link between the pesticide chlorpyrifos and a significantly increased risk of Parkinson's disease. The study was published on June 28, 2026, in the journal Molecular Neurodegeneration.
The team analyzed data from 829 Parkinson's patients and 824 healthy control subjects from the ongoing "Parkinson's Environment and Genes" study. Individuals with long-term residential exposure to chlorpyrifos were more than 2.5 times more likely to develop Parkinson's disease than unexposed individuals. California pesticide registries allowed for the estimation of exposure over many years.
Additional laboratory experiments on mice confirmed the suspicion: after 11 weeks of inhaling the substance, the animals showed motor impairments and a loss of dopamine-producing neurons – precisely the cells that also die off in humans with Parkinson's disease. Furthermore, toxic alpha-synuclein proteins accumulated in the brain.
The researchers identified a disruption of autophagy – the cellular recycling system – as the underlying mechanism. When this process was restored, nerve cells could be protected.
Although chlorpyrifos was banned for domestic use in 2001 and received agricultural restrictions in 2021, the substance continues to be used worldwide. The study underscores the need to take environmental exposures seriously as a risk factor for Parkinson's disease and points to autophagy as a potential therapeutic approach.
