In November 2025, EPA said there is more uncertainty than it once thought about whether paraquat can turn into vapor after it is sprayed. It said it would require manufacturers to provide more data, and a data call-in notice was posted to EPA’s public docket in June 2026. The update is about how people near fields might breathe in paraquat. It does not address whether paraquat causes Parkinson’s disease.
Spray drift and vapor are different
Spray drift is when droplets move off target while the product is being sprayed, carried by wind. EPA already requires drift-reducing steps for paraquat. Its 2021 interim decision added a buffer from homes for aerial spraying and required spray-drift label language. (EPA)
Volatilization is different. It happens after spraying, when residue on plants or soil turns into a gas that can move through the air. How easily this happens depends partly on a chemical’s vapor pressure.
EPA’s November 2025 update is about volatilization, not spray drift.
What changed
In January 2024, Syngenta Crop Protection gave EPA a new study on paraquat’s vapor pressure. Federal law says companies must tell EPA about new information on possible harm. The study showed a higher vapor pressure than EPA had used before. EPA finished reviewing it in March 2024 and began a broader review. (EPA)
On November 13, 2025, EPA released that review. It combined the new study with earlier data and concluded that “there is greater uncertainty regarding the potential for paraquat to volatilize than previously considered.” EPA said this matters because vapor could reach “workers and bystanders who live or work near or adjacent to treated fields.” (EPA)
What EPA is doing next
To clear up the uncertainty, EPA said it would issue a data call-in. That is a formal order telling paraquat makers to provide more data. A Paraquat Generic Data Call-In Notice was posted to EPA’s public paraquat docket on June 8, 2026. (Regulations.gov)
When the data come in, EPA says it will review them and publish an updated analysis. This is part of its regular safety review of paraquat, called registration review. EPA may also update its estimate of how much paraquat bystanders could breathe in. Before it makes a final decision, EPA also plans to study effects on endangered species and on the body’s hormone system. (EPA) As of October 3, 2026, we found no later EPA announcement replacing the November 2025 update.
What the update does not say
The update is about how sure EPA can be of one exposure estimate. It does not find that paraquat vapor has harmed anyone, and it does not find that paraquat causes Parkinson’s disease. EPA’s separate position on Parkinson’s disease is that it has not found a clear link from labeled uses. (EPA)
The update also does not change today’s safety rules. Paraquat products remain restricted-use pesticides that only certified applicators may use. Those rules have changed over the years, so the rules today may not be the ones that applied when someone was exposed.
For people who lived or worked near treated fields, being nearby is not, by itself, evidence of exposure. A review would still need to identify the product, the spraying, and the location. Our paraquat page explains what a review considers. This article is general information, not legal or medical advice.
This article is general information about how these cases work. It is not legal advice, it does not create an attorney-client relationship, and no two claims are alike. If something here sounds like your situation, the useful next step is a conversation about the facts.
