By Jamie Martin
A new California lawsuit involving chlorpyrifos is bringing renewed attention to potential health risks associated with long-term pesticide exposure and the importance of preventing agricultural chemicals from moving beyond the intended application area.
Wisner Baum LLP has filed a lawsuit in Los Angeles County Superior Court against The Dow Chemical Company, Corteva and three commercial nurseries on behalf of a man diagnosed with early-onset Parkinson’s disease.
The complaint alleges the plaintiff was exposed to chlorpyrifos for years while living next to commercial nursery operations in Los Angeles County. It claims pesticide manufacturers failed to adequately investigate and disclose potential neurological risks associated with the insecticide.
The allegations have not been proven in court.
Lawsuit alleges years of chlorpyrifos exposure
According to the complaint, the plaintiff lived near commercial nurseries where chlorpyrifos was allegedly applied from approximately 2003 through 2020.
For about a decade, his home was reportedly only 20 feet from one nursery, with no barrier separating the properties. At a later residence, his backyard fence directly bordered another nursery, according to the lawsuit.
The complaint names Abeja Nursery, Azul & Verde Nursery and ABC Nursery, Inc., alleging they failed to take adequate precautions to prevent pesticide drift and other off-site exposure.
The lawsuit also names Corteva, Inc., Corteva Agriscience LLC and The Dow Chemical Company. It alleges the companies designed, manufactured, marketed, sold or distributed chlorpyrifos products without adequately warning about potential long-term neurological effects.
“People living near pesticide applications should not have to guess what is being sprayed or whether it could affect their health,” said Sasha Shariati, a Wisner Baum attorney representing the plaintiff.
“This case will examine what the defendants knew, how they communicated about chlorpyrifos, and whether reasonable precautions could have reduced exposure to nearby residents.”
Research examining Parkinson’s connection
Chlorpyrifos is an organophosphate insecticide that affects the nervous system through inhibition of acetylcholinesterase, an enzyme necessary for normal nerve function.
Researchers have increasingly examined whether long-term exposure to the insecticide could also be associated with Parkinson’s disease.
Recent research involving California agricultural communities found that people estimated to have the highest long-term chlorpyrifos exposure were more than 2.5 times as likely to develop Parkinson’s disease compared with those without the exposure.
An association identified in an epidemiological study does not establish that chlorpyrifos caused an individual person’s Parkinson’s disease. Parkinson’s is a complex condition potentially involving genetic, environmental and other factors.
The lawsuit nevertheless argues that pesticide manufacturers should have done more to investigate and communicate potential long-term neurological risks.
“Chlorpyrifos manufacturers had decades to study what this chemical does to the human nervous system,” Shariati said. “This lawsuit seeks to hold them accountable for what they knew and what they chose not to tell the public.”
Chlorpyrifos can still be used on some U.S. crops
The lawsuit comes during an evolving regulatory period for chlorpyrifos in the United States.
The U.S. Environmental Protection Agency revoked food tolerances for chlorpyrifos in 2021, effectively stopping its use on food crops. However, that rule was vacated by the U.S. Court of Appeals for the Eighth Circuit in 2023, resulting in the reinstatement of the tolerances.
Registrants have since voluntarily cancelled most food and feed uses.
EPA-approved amended labels retain food uses on 11 crops: alfalfa, apples, asparagus, tart cherries, citrus, cotton, peaches, soybeans, strawberries, sugar beets and spring and winter wheat.
Those uses are limited geographically and are subject to application restrictions. EPA's registration review of chlorpyrifos continues.
That makes it particularly important for farmers and professional applicators who still use chlorpyrifos products to confirm that the crop, state and intended application are permitted by the current product label before spraying.
Drift remains an important agricultural issue
Regardless of the outcome of the California lawsuit, the case highlights an issue affecting virtually every pesticide application: keeping crop protection products on the intended target.
Modern pesticide labels can establish requirements related to application methods, weather conditions, buffers, equipment and other measures intended to reduce unacceptable exposure.
Good recordkeeping is also important. Application date and time, product and rate, field location, weather conditions and other required information can help document that an application was conducted according to applicable requirements.
Those practices can become particularly important where cropland, greenhouses or nurseries are located close to residential properties.
The California complaint specifically alleges that the nursery defendants failed to maintain adequate buffers and application controls or appropriately notify nearby residents.
California ended chlorpyrifos use
Chlorpyrifos is no longer available for the agricultural uses at issue in the California lawsuit.
California regulators reached an agreement with pesticide manufacturers that ended sales of chlorpyrifos products to growers in February 2020. Growers were no longer permitted to possess or use the products after December 31, 2020.
The state had previously imposed additional restrictions, including a prohibition on aerial application and buffer requirements.
Chlorpyrifos faces international phase-out
Restrictions are expanding beyond California and the United States.
Parties to the Stockholm Convention on Persistent Organic Pollutants agreed in 2025 to list chlorpyrifos for elimination under Annex A of the Convention.
The listing enters into force December 16, 2026, although the agreement provides for specific exemptions under which registered parties may continue certain production or uses.
Case could increase focus on historical pesticide exposure
The California lawsuit could contribute to a broader debate around the long-term effects of pesticide exposure.
While much of the previous regulatory attention around chlorpyrifos concentrated on developmental neurotoxicity and exposure among children, Parkinson’s research raises different questions about chronic exposure over many years.
That may bring additional attention to historical exposure among agricultural workers, pesticide applicators and people who lived near farms, nurseries and other operations where chlorpyrifos was regularly applied.
Wisner Baum says it is evaluating additional claims involving people diagnosed with Parkinson’s disease following chlorpyrifos exposure or possible exposure.
For agriculture, the case offers another reminder that decisions surrounding pesticide use can extend well beyond the season in which an application occurs.
Photo Credit:gettyimages-pattanaphong-khuankaew
Categories: National