Key facts
- California has banned paraquat, a highly toxic herbicide, with a phase-out over two years.
- The ban was announced by the California Department of Pesticide Regulation (DPR) after a new state law mandated a re-evaluation of the pesticide's risks.
- Paraquat is linked to Parkinson's disease, cancer, organ failure, and is considered lethal with no antidote.
- The herbicide is already outlawed in over 70 countries, including China, the UK, and the EU.
- The US Environmental Protection Agency (EPA) has reapproved paraquat for use in 2021 and 2024.
- Industry makers, including Syngenta, chose to withdraw use permits rather than share updated risk data with regulators.
California has banned paraquat, a highly toxic and controversial herbicide used on millions of acres of cropland, marking a significant victory for public health advocates. The decision, announced by the California Department of Pesticide Regulation (DPR), will phase out the pesticide over two years.
Paraquat is characterized by health advocates as a deadly substance virtually proven to cause Parkinson’s disease, and it is already outlawed in more than 70 countries, including China, the UK, and the EU. Despite this, the U.S. Environmental Protection Agency (EPA) reapproved it for use in 2021 and again in 2024. California, the largest agricultural producer in the U.S. and a major user of paraquat, is the second state to prohibit the herbicide, following Vermont.
The ban comes after the state legislature passed a law in 2024 requiring the pesticide division to re-evaluate the substance’s health risks. Nathan Donley, environmental health science director with the Center for Biological Diversity, described paraquat as "the most acutely lethal pesticide ever made." Approximately 14 million pounds of paraquat are sprayed annually on various U.S. crops, with its use having tripled between 2008 and 2018.
Exposure to paraquat is linked to severe health consequences, including death, cancer, heart, kidney, and liver failure, and lung scarring. There is no antidote for paraquat poisoning. Research indicates it interferes with dopamine production, and epidemiological studies in California farming communities have shown an increased incidence of Parkinson's disease among those exposed.
The DPR's preliminary review confirmed human health concerns, including associations with thyroid disease, reproductive harm, and birth defects, as well as risks to birds and mammals. Instead of sharing updated data on health and environmental risks, pesticide makers, including the Chinese-owned firm Syngenta, decided to withdraw their use permits. Syngenta also announced it would stop producing the substance altogether.
Advocates believe the industry's decision to withdraw was a strategic move to avoid sharing alarming health data. The California decision is expected to increase pressure on the EPA, which faces ongoing lawsuits from groups like Earthjustice, alleging it has ignored scientific consensus linking paraquat to Parkinson's. Critics point to industry influence and weak federal pesticide laws as reasons for the EPA's continued approval of the substance.