WASHINGTON— Following years of advocacy from farmworker groups, environmentalists and health organizations, the California Department of Pesticide Regulation has announced that the last paraquat pesticide product was canceled in the state and existing stocks of the products must be sold or destroyed in two years.

The Parkinson’s disease-linked pesticide is banned in more than 70 countries and is one of the most lethal herbicides approved for use in the United States. There is no antidote for paraquat poisoning and the pesticide’s severe toxicity is highlighted on an Environmental Protection Act website titled “Paraquat Dichloride: One Sip Can Kill.”

California’s phase out follows Vermont’s first-in-the-nation ban of paraquat and contrasts sharply with inaction by the EPA at the federal level. Following years of analysis paralysis, the agency recently announced that it will host a roundtable to discuss paraquat regulation with stakeholders.

“California and other states are taking aggressive steps to protect people from this dangerous poison, but the EPA continues to spin a web of red tape to obscure paraquat’s well-documented harms,” said Nathan Donley, environmental health science director at the Center for Biological Diversity. “The writing is on the wall — paraquat is on its way out. The question now is how long it will take the EPA to actually do its job and start protecting people instead of the profits of pesticide companies.”

California is the largest U.S. user of paraquat. The pesticide’s use is heavily concentrated in the San Joaquin Valley, with more than three-quarters of the total used in just eight San Joaquin Valley counties. Paraquat is one of the state’s five most-used pesticides.

California’s Department of Pesticide Regulation initiated reevaluation of paraquat after conservation and public health groups requested that it reassess approval of the herbicide and ban its use in the state. In 2024 California passed A.B. 1963, which required the department to continue reevaluating the use of paraquat.

The state’s preliminary assessment identified potential risks for birds and mammals, including some of California’s most imperiled species like the San Joaquin kit fox and Swainson’s hawk. It also found that reducing the risks to wildlife with mitigation measures that restrict paraquat’s use may not be effective because the herbicide is so persistent in the environment.

The preliminary findings also confirmed substantial public health harms such as an association between paraquat and thyroid disease, as well as birth and reproductive harms.

Ingesting or inhaling paraquat, or exposing it to the skin, can lead to a range of health risks short of death, including cancer, heart failure, kidney failure, liver failure and scarring of the lungs. Farmworkers and agricultural communities are at greater risk of inhaling paraquat because the herbicide can spread on dust that blows across fields and into neighborhoods.

Paraquat has been linked to Parkinson’s disease, a devastating neurological condition with no known cure. Researchers found that paraquat exposure in California’s agricultural communities leads to increased risks of Parkinson’s and thyroid cancer.

In 2021 farmworker groups, environmentalists and health organizations, represented by Earthjustice, filed a lawsuit challenging the EPA’s reapproval of paraquat. That legal challenge is ongoing while the agency reviews the risks of the herbicide.