Chlorpyrifos: Health Risks, Exposure Dangers and Safety Concerns

Chlorpyrifos is a broad-spectrum pesticide designed to kill insects. It belongs to the organophosphate class of chemicals that kill bugs by affecting their nervous systems and brains. Farmers most often use it against pests that damage agricultural crops.

Commercial products combine chlorpyrifos with solvents and other ingredients so farmers can spray it, mix it into soil or apply it in another form allowed by the product label. Because the chemical can contaminate air and water, people mainly experience chlorpyrifos exposure when working in agriculture or living near a heavily sprayed area. People who work with the pesticide in commercial farming or other agricultural jobs are most at risk of exposure.

Common Uses and Trade Names

The most common chlorpyrifos products were available under trade names like Lorsban and Dursban. Dow developed and marketed major chlorpyrifos products, and after Dow’s merger with DuPont, the company formed Corteva Agriscience as a subsidiary of its agricultural business. Corteva stopped making Lorsban in 2020.

The EPA negotiated an end to most residential chlorpyrifos uses in 2000, which removed many indoor and around-the-home applications. Current federal food-use labels are much narrower. Today, the EPA restricts chlorpyrifos use to 11 crops in specific states: Alfalfa, apples, asparagus, tart cherries, citrus, cotton, peaches, soybeans, strawberries, sugar beets and spring and winter wheat.

Chlorpyrifos interferes with the breakdown of acetylcholine, an enzyme that nerve cells need to function normally. As a result of this interference, too much acetylcholine builds up in the body, leading to overstimulation of cells.

In insects, this causes neurotoxicity and eventually death. In humans, nerves and muscles may not function correctly, and the body makes more enzymes to keep functioning normally. Typically, the body breaks down the chlorpyrifos and excretes most of it in feces and urine within a few days. But sometimes, chlorpyrifos can find its way into the nervous system and stay in the body for a longer time.

The Neurotoxic Mechanism Behind the Lawsuits

Chlorpyrifos kills insects by affecting enzymes in their brains. This same mechanism also affects the human brain, leading to Parkinson’s disease in adults and neurological problems in children, according to lawsuits.

Neurodevelopmental harm in children, Parkinson’s disease risk and acute chlorpyrifos poisoning are some of the biggest safety concerns linked to chlorpyrifos.

Neurodevelopmental Harm in Children

Several studies have followed children whose mothers experienced chlorpyrifos exposure during pregnancy and linked the pesticide to an increased risk of neurodevelopmental harm. A 2025 study in JAMA Neurology reported children exposed to chlorpyrifos in the womb had differences in brain structure and function as well as poorer motor performance.

In 2014, the CHARGE study found that children whose mothers lived within a mile of organophosphate application sites had a 60% higher risk of autism spectrum disorder and developmental delay.

Parkinson’s Disease Risk

Studies have associated long-term chlorpyrifos exposure with developing Parkinson’s disease. For example, a 2025 study in Molecular Neurodegeneration evaluated 829 people with Parkinson’s disease alongside 824 control subjects. People with long-term exposure to chlorpyrifos at work had more than 2.5 times the risk of developing Parkinson’s disease compared to people who weren’t exposed to chlorpyrifos.

Farmworker and Bystander Exposure

Farm and agricultural workers who mix, load or apply chlorpyrifos may have direct contact with concentrated products or exposure from spraying the product. Field workers may come into contact with pesticide residues when they enter treated areas.

Pesticides drift and spread beyond the spraying area, potentially reaching neighboring homes, schools, vehicles or workplaces. Workers may bring home contaminated clothing, shoes and equipment that can bring residue into a vehicle or home, exposing family members.

Signs and Symptoms to Watch For

Indications of chlorpyrifos exposure may appear within a few minutes to hours and can last for weeks. Small amounts of chlorpyrifos exposure may cause runny nose, tears and increased saliva production. Sweating, headaches, nausea and dizziness may also occur.

More serious exposures can cause abdominal muscle cramps, vomiting, muscular twitching, loss of coordination and tremors or weakness. Some people may develop diarrhea or blurred or darkened vision. Severe poisoning symptoms include unconsciousness, convulsions, loss of bladder and bowel control, breathing problems and paralysis.

Chlorpyrifos regulation has changed over the years through EPA decisions, court rulings, product cancellations and label changes. Before using any chlorpyrifos product, check the current labeling and state law for proper uses and safety considerations.

Any chlorpyrifos bans were temporary, and the government still allows its use on specific crops. However, the EPA heavily restricts its commercial use to 11 crops. In residential settings, companies can still use chlorpyrifos in ant and roach bait.

Chlorpyrifos Ban Timeline

Where Do People Still Use Chlorpyrifos?

Chlorpyrifos currently has commercial registrations for use on alfalfa, apples, asparagus, tart cherries, citrus, cotton, peaches, soybeans, strawberries, sugar beets and wheat. Each state may note additional restrictions or uses on the label.

Global Bans

The European Union chose not to renew chlorpyrifos in 2020, effectively banning its use. Other countries that have banned chlorpyrifos outright include Canada, Thailand and the United Kingdom.

People diagnosed with Parkinson’s disease after long-term occupational or residential chlorpyrifos exposure are investigating claims against pesticide manufacturers, such as Dow and Corteva. In addition, parents of children who developed neurodevelopmental disorders after receiving chlorpyrifos exposure in the womb or in the first four years of life may also qualify to file chlorpyrifos lawsuits.

Lawsuits say enough information was available for manufacturers to know chlorpyrifos was dangerous, but they failed to warn the public. These claims also say manufacturers defectively designed the pesticide because it can cause dangerous health problems, and that safer alternatives exist. Similar lawsuits over paraquat and Roundup highlight the ongoing risks of commercial pesticide use.