Common pesticide chlorpyrifos linked to dramatically higher Parkinson's risk

A new UCLA study published in Molecular Neurodegeneration has found a striking link between long-term exposure to chlorpyrifos — a pesticide used extensively in agriculture for decades — and Parkinson's disease. Analyzing data from over 1,600 participants in UCLA's Parkinson's Environment and Genes study, researchers found that people with prolonged residential exposure to the chemical had more than 2.5 times the risk of developing Parkinson's compared to those with no exposure.

But the team didn't stop at correlation. Using mouse and zebrafish models, they showed that chlorpyrifos disrupts autophagy — the brain's natural cellular recycling system — causing toxic proteins (like alpha-synuclein) to accumulate and dopamine-producing neurons to die off. These are hallmark features of Parkinson's disease. Crucially, when researchers restored the autophagy process or removed the problematic protein in lab models, neurons were protected from damage.

Key Takeaways:

• Chlorpyrifos residential use was banned in the U.S. in 2001, but agricultural use continued until 2021 — and it remains in use globally
• The pesticide triggers dopamine neuron loss, brain inflammation, and abnormal alpha-synuclein buildup in animal models
• Restoring autophagy function shielded neurons, pointing to a potential therapeutic target

Why it matters: With nearly 1 million Americans living with Parkinson's, identifying specific environmental triggers — and the biological pathways they exploit — is a major step toward prevention and treatment. People with significant past pesticide exposure may benefit from closer neurological monitoring.