A new study by researchers has shown that long-term exposure to the widely used pesticide chlorpyrifos increases the risk of developing Parkinson’s disease by more than 2.5 times. The findings were published in the journal Molecular Neurodegeneration and combine population-level data analysis with laboratory experiments, making the conclusions particularly compelling.

The researchers analyzed data from 829 patients with Parkinson’s disease and 824 healthy participants, comparing long-term residence near areas where chlorpyrifos was used with the incidence of the disease. They found that people with prolonged exposure to this pesticide had a more than 2.5-fold higher risk of developing Parkinson’s disease compared with those who had not been exposed.

To better understand how this chemical may damage the brain, the researchers conducted experiments in animals. Mice were exposed to a chlorpyrifos aerosol for 11 weeks, simulating typical human exposure. These animals developed motor impairments and a loss of dopamine-producing neurons—closely mirroring what is observed in people with Parkinson’s disease.

Additional experiments in zebrafish revealed that chlorpyrifos disrupts autophagy—a cellular process responsible for removing damaged proteins and organelles—which may be one of the mechanisms leading to neuronal death. When researchers restored this process or removed the protein alpha-synuclein, neurons were protected from damage.

Chlorpyrifos was banned for household use in the United States in 2001, and its agricultural use has been restricted since 2021. However, it is still applied to many crops in the U.S. and remains widely used in other countries.

These results add strong evidence that environmental factors play a significant role in the development of Parkinson’s disease, alongside genetic predisposition. Understanding the specific effects of pesticides on the nervous system may help in developing strategies for prevention, early detection, and potential therapeutic interventions.