A new study from UCLA Health has found that living near areas where the pesticide chlorpyrifos was used for long periods may increase the risk of developing Parkinson’s disease by more than 2.5 times.
This research helps explain how exposure to this chemical might damage brain cells and lead to serious health problems later in life.
Parkinson’s disease is a brain disorder that affects nearly one million Americans. It causes symptoms like shaking, stiffness, and trouble moving. While some people are born with genes that increase their risk, scientists now believe that environmental factors, like contact with harmful chemicals, also play a big role.
Chlorpyrifos is one of those chemicals. It has been used for decades on farms to control insects. While it was banned for use in homes in 2001 and limited for farming in 2021, it is still used on some crops in the U.S. and in many other countries.
In this new study, researchers wanted to find out how much chlorpyrifos might affect people who live near areas where it is sprayed. They used data from 829 people with Parkinson’s disease and 824 people without it.
All of them were part of a long-term study at UCLA. The team looked at where these people lived and worked and compared that with pesticide use records in California to estimate how much chlorpyrifos they were exposed to over time.
The results were striking. People who lived near areas with heavy chlorpyrifos use had more than double the risk of getting Parkinson’s. But the researchers didn’t stop there. They also did lab experiments to understand how this pesticide could hurt the brain.
In one experiment, mice were exposed to the pesticide through the air for 11 weeks, similar to how people might breathe it in from the environment. These mice developed movement problems and lost brain cells that produce dopamine—a key chemical that helps control movement. These are the same types of cells that are damaged in people with Parkinson’s.
The study also found that the brains of the exposed mice had more inflammation and buildups of a harmful protein called alpha-synuclein. This protein forms clumps in the brains of people with Parkinson’s.
In another part of the study, the scientists used zebrafish and discovered that chlorpyrifos interferes with autophagy, a natural process the body uses to clean out damaged cells and proteins. When this process was restored or the harmful protein was removed, the brain cells were protected.
These results are important because they show not only a strong link between the pesticide and Parkinson’s disease but also explain how the chemical may cause damage. The findings suggest that chlorpyrifos is not just one pesticide among many—it may be a key trigger of the disease for people exposed to it over time.
Even though chlorpyrifos use has gone down in the U.S., many people were exposed in the past. Also, other similar chemicals are still being used today.
That’s why scientists are calling for more research on other pesticides and ways to protect the brain. They also say that people who lived near areas with heavy pesticide use might benefit from early screening or future treatments that protect the brain.
The researchers, led by Dr. Jeff Bronstein from UCLA Health, believe this study shows clear evidence that chlorpyrifos raises the risk of Parkinson’s. They also believe that finding new ways to support the brain’s natural cleaning system, called autophagy, might help prevent or slow the disease in people who have already been exposed.
This research is an important step forward. It reminds us that the environment around us—especially what we breathe and are exposed to daily—can have lasting effects on our health.
It also shows that even long-banned chemicals can still affect people years later. With this new understanding, scientists hope to find better ways to protect people from Parkinson’s and develop new treatments in the future.
If you care about Parkinson’s disease, please read studies that Vitamin B may slow down cognitive decline, and Mediterranean diet could help lower risk of Parkinson’s.
For more health information, please see recent studies about how wheat gluten might be influencing our brain health, and Olive oil: a daily dose for better brain health..
The study is published in Molecular Neurodegeneration.
Copyright © 2025 Knowridge Science Report. All rights reserved.
