Yikes! While writing the last post, I came across a recent study of another pesticide linked with the development of Parkinson's disease. While the weed killer paraquat has long been linked to Parkinson's disease, certain other pesticides are also linked - such as chlorpyrifos.
Chlorpyrifos is a widely used insecticide in agriculture. While now banned for household use, homeowners used to use it (e.g., in the product Raid) for insect control for many years.
The study researchers (at the medical school at UCLA) found that long-term residential exposure to chlorpyrifos is associated with more than a 2.5 times increased risk of developing Parkinson's disease. They studied humans, mice, and zebrafish to reach their conclusions. They found that chlorpyrifos damages dopamine-producing brain cells - which are the same cells damaged in Parkinson's disease.
From Medical Xpress: Widely used pesticide linked to more than doubled Parkinson's risk
A new study from UCLA Health has found that long-term residential exposure to the pesticide chlorpyrifos is associated with more than a 2.5-fold increased risk of developing Parkinson's disease.
The research, published in the journal Molecular Neurodegeneration, combines human population data with laboratory experiments showing how the pesticide damages dopamine-producing brain cells, providing biological evidence for the link.
Nearly one million Americans live with Parkinson's disease, a progressive neurological disorder that causes tremors, stiffness and difficulty with movement. While genetics plays a role, environmental factors like pesticide exposure are increasingly recognized as important contributors. Chlorpyrifos has been widely used in agriculture for decades.
Though its residential use was banned in 2001, and agricultural use was restricted in 2021, chlorpyrifos is still used on many crops in the US and widely used in other countries.
Researchers analyzed data from 829 people with Parkinson's disease and 824 without the condition, all part of UCLA's long-running Parkinson's Environment and Genes study. The team used California's pesticide use reports along with participants' residential and work addresses to estimate individual exposure to chlorpyrifos over time.
To understand how the pesticide might cause brain damage, researchers exposed mice to aerosolized chlorpyrifos for 11 weeks using inhalation methods that mimic how humans typically encounter the chemical. They also conducted experiments in zebrafish to identify the specific biological mechanisms of damage.
People with long-term residential chlorpyrifos exposure had more than 2.5 times the risk of developing Parkinson's disease compared to those without such exposure. Mice exposed to the pesticide developed movement problems and lost dopamine-producing neurons, the same cells that die in Parkinson's patients.
The exposed mice also showed brain inflammation and abnormal accumulation of alpha-synuclein, a protein that clumps in Parkinson's disease. Zebrafish experiments revealed that chlorpyrifos damages neurons by disrupting autophagy, the cellular process that clears damaged proteins. When researchers restored this cleanup process or removed synuclein protein, the neurons were protected from damage.
The findings identify autophagy dysfunction as a potential target for developing treatments that could protect the brain from pesticide damage. Researchers note that while chlorpyrifos use has been reduced in recent years in the US, many people were exposed in the past and similar pesticides are still used widely.