Scientists at UCLA Health have found that a widely used pesticide called chlorpyrifos may hurt the brain more than we thought. People who lived close to where this chemical is used have a 2.5 times higher chance of getting Parkinson’s disease.
What Is Parkinson’s Disease?
Parkinson’s is a brain disorder that makes it hard to move. It happens when special brain cells that make a chemical called dopamine die. Dopamine helps us control movement, balance, and coordination. When there isn’t enough dopamine, people may shake, feel stiff, move slowly, or lose balance.
Why Look at Pesticides?
Scientists know that some chemicals used in farming can damage nerves. But it is hard to point to one exact pesticide and explain how it hurts the brain. Chlorpyrifos has been used for many years on farms. Even though it was banned for home use in 2001 and its farm use was limited in 2021, it is still applied to many crops in the U.S. and other countries.
How the Study Measured Exposure
The researchers used data from 829 people with Parkinson’s and 824 people without the disease. All participants are part of UCLA’s long‑term study of Parkinson’s and the environment. By matching each person’s home and work addresses with California’s pesticide‑use records, the team estimated how much chlorpyrifos each person breathed over many years.
They discovered that those who lived where chlorpyrifos was sprayed had more than two‑and‑a‑half times the risk of developing Parkinson’s compared with people who had little or no exposure.
What the Lab Tests Showed
To see why the pesticide might cause disease, scientists exposed mice to tiny droplets of chlorpyrifos for 11 weeks, copying the way humans might inhale the chemical from the air. The mice started to move poorly and lost dopamine‑producing brain cells—the same cells that die in Parkinson’s.
They also found swelling in the brain and a build‑up of a protein called alpha‑synuclein. This protein can clump together and block normal brain function in people with Parkinson’s.
Disrupting the Brain’s Clean‑Up Crew
Further experiments with zebrafish revealed that chlorpyrifos interferes with a process called autophagy. Autophagy is like a cell’s recycling system; it removes damaged proteins and waste. When this system stops working, nerve cells become easy targets for injury.
When researchers helped the cells restore autophagy or removed the harmful alpha‑synuclein protein, the nerve cells were protected. This suggests the pesticide may raise Parkinson’s risk by blocking the brain’s natural clean‑up system.
What Comes Next?
The study points to autophagy as a possible target for new medicines that could shield the brain from pesticide damage. Although chlorpyrifos use has dropped in the United States, many people were exposed before the restrictions, and similar chemicals are still used worldwide.
Future research will test whether other common pesticides also block autophagy and whether boosting this clean‑up process can lower Parkinson’s risk for people who have been exposed.
Doctors may start watching people with known past exposure more closely for early signs of neurological problems.