Chlorpyrifos is an organophosphate insecticide, a class of chemicals developed from nerve-agent research. It kills insects by blocking an enzyme the nervous system needs. The same mechanism is why scientists have worried about its effect on developing human brains since the 1990s. Dow introduced it in 1965 under the Dursban and Lorsban brands; Corteva, spun off from DowDuPont, inherited the line and stopped producing Lorsban in 2020.
The regulatory arc
1995. The EPA fines DowElanco $732,000 for failing to report adverse health incidents, including chronic neurological effects.
2000. Residential uses are withdrawn. Agricultural uses continue.
2021. After years of litigation by health groups, the EPA revokes all food tolerances, concluding it cannot find any level safe for children. A federal appeals court later sends the rule back on procedural grounds, and the agency has since pursued narrower restrictions. California banned it in 2020.
The science that drove the ban — prospective birth-cohort studies at Columbia, UC Berkeley, and Mount Sinai — is the same science the lawsuits rely on. The regulatory record does the plaintiffs' work of showing what was knowable and when.
Direct2Attorney · Legal ExplainerTwo litigation tracks
Neurodevelopmental claims
Children; California state courts since 2021- Defendants: Corteva, Dow, applicators, growers, and municipalities
- Theories: design defect, failure to warn, negligence, nuisance
- Injuries: autism, ADHD, cognitive and motor deficits
- Status: active; Corteva has accrued for certain claims
Parkinson's claims
Adults; first filed June 2026- Defendants: Corteva, Dow, FMC
- Theory: chronic occupational exposure caused Parkinson's
- Model: the paraquat MDL
- Status: single case in federal court in Pennsylvania; more expected
What plaintiffs must prove
Exposure is the first hurdle: where the plaintiff lived or worked, what was applied nearby, and when. California’s pesticide use reporting system makes this unusually documentable there. Causation is the second: expert testimony connecting the exposure to the diagnosis, supported by the epidemiological literature. The third is knowledge: what the manufacturer knew about neurological risk and what it disclosed. The 1995 enforcement action and internal documents are central to that.
Why there is no MDL yet
The children’s cases have been filed in state courts, often against local defendants, which keeps them out of federal consolidation. If the adult Parkinson’s cases multiply in federal court, an MDL request is likely. That pattern — state cases first, federal MDL later — is common in pesticide litigation.
What this means if you're considering a claim
This is a litigation where exposure history matters more than almost anything else. If you can place yourself or a family member near treated agriculture or in a job handling the product, and there is a qualifying diagnosis, a free review can assess whether a participating firm sees a claim on either track.
Think your exposure fits?
Free, confidential review by a participating firm.
Common Questions
Some agricultural uses remain under narrowed federal rules; California and several other states have banned it. Residential products were withdrawn in 2000.
Complaints have named both. Applicators and growers have duties around drift and notification.
Lorsban, Dursban, Cobalt, Nufos, Warhawk, and others. Product confirmation is part of case development.
The filed case involves long-term occupational handling. Screening criteria are still developing.
No. Direct2Attorney’s review is free, and participating law firms typically work on contingency, meaning fees are generally paid only if there is a recovery. Confirm fee terms in writing with the firm.
