California will phase out paraquat, a pesticide tied to birth defects and thyroid issues, after manufacturers withdrew their products following new state health assessments. The move follows years of advocacy and recent regulatory review.
California regulators have announced that paraquat, a widely used pesticide associated with birth defects and thyroid problems, will be phased out across the state. The decision comes after the California Department of Pesticide Regulation required manufacturers to provide new scientific data addressing gaps in the agency's toxicology database. Instead, companies voluntarily canceled their product registrations, effectively ending paraquat's legal use in California.
Paraquat, also known as paraquat-dichloride, has been banned in dozens of countries and was recently prohibited in Vermont, according to the Environmental Working Group. California is the largest user of paraquat in the United States, with most applications concentrated in the San Joaquin Valley. The state's decision follows a 2024 reevaluation of the chemical, which identified potential links between paraquat exposure and both thyroid impacts and birth defects. The review also found evidence that paraquat may harm wildlife, particularly birds.
Existing Stocks May Remain for Two Years
The last product cancellation occurred on Thursday, marking the end of new paraquat sales in California. Under state law, licensed dealers may continue to possess and sell existing stocks of paraquat for up to two years from the date of cancellation. This means paraquat could remain in limited use until 2026, but no new product registrations will be accepted.
Farmworker and environmental groups have long advocated for a ban on paraquat, citing health risks to agricultural workers and nearby communities. The Environmental Working Group noted that the phaseout follows a March incident in Dorris, California, where a container of paraquat fell from a truck, spilling about 60 gallons and prompting a lockdown of 600 residents, including an elementary school. Bernadette Del Chiaro, senior vice president for California with the Environmental Working Group, called the state's action overdue, pointing to the lack of protection for farmworkers and residents in areas where paraquat is used.
Farmers Raise Concerns Over Fewer Weed-Control Options
California Farm Bureau spokesperson Isabella Quinonez told the Los Angeles Times that paraquat has been an important tool for farmers and expressed concern about the increasing difficulty of the state's agricultural marketplace as more pesticides are restricted or banned. Meanwhile, thousands of lawsuits have been filed against Syngenta, a major manufacturer of paraquat, alleging a link between the chemical and Parkinson's disease. While some studies have suggested a possible connection, results have been mixed and Syngenta has denied the allegations, according to the Times.
California's phaseout of paraquat is part of a broader trend toward stricter pesticide regulation and increased scrutiny of chemicals with potential health and environmental risks. A 2024 state law requires ongoing reevaluation of pesticides, and the Department of Pesticide Regulation has indicated it will continue to assess other products as new scientific information becomes available.
Phaseout Could Reshape Agricultural Practices
Paraquat's removal from the California market is expected to affect growers who have relied on the chemical for weed control, particularly in the state's major agricultural regions. The Department of Pesticide Regulation has encouraged the adoption of alternative pest management practices that prioritize health and environmental safety.
California's regulatory process for pesticides involves periodic scientific review, public comment, and coordination with manufacturers. When new health or environmental concerns are identified, the department can require additional data or restrict use. If manufacturers do not comply, product registrations may be canceled, as occurred with paraquat. The state's approach reflects a growing emphasis on precaution and transparency in agricultural chemical oversight.
