California passes law ordering review of paraquat weed killer

By Carey Gillam

Efforts by some California lawmakers to ban the controversial weed killing chemical paraquat ended this week with passage of a law that keeps the chemical in use but requires a reevaluation by regulators within the next five years.

Backers of a ban cited scientific evidence linking paraquat to a range of health problems, including the incurable brain disease known as Parkinson’s, as a key reason to outlaw paraquat use in the state.

The California State Assembly earlier this year had approved what was referred to as a “moratorium” on paraquat that would have taken effect in January 2026 and provided for a process that have would have given state regulators an opportunity to reevaluate paraquat and potentially reapprove the chemical with or without new restrictions.

But state Senate amendments killed any moratorium or restriction on use. The bill, as passed, now only requires state pesticide regulators to complete a reevaluation of paraquat by January 2029.

California Assemblymember Laura Friedman said the fact that the legislature passed requirements for a regulatory reevaluation is still a win.

“With the mounting medical evidence indicating that paraquat is simply too toxic to remain in wide use, I am very confident that [state regulators] will not only do a thorough re-evaluation of paraquat, but either ban it outright or place greater restrictions on its use,” Friedman said in a statement.

“The legislature has spoken loud and clear,” Bill Allayaud, vice president of government affairs for the Environmental Working Group (EWG) said in a press release. EWG was a key backer of the bill. “They want the science on paraquat to be considered now while farmworkers and nearby residents are exposed – not down the road.”

There was staunch opposition to a ban on paraquat. A legislative analysis of the law cites a “coalition of opponents, including pesticide manufacturers, chemical industry trade associations, and agricultural trade organizations,” opposing the law.

The industry opponents also object to a regulatory reevaluation of paraquat, saying it will “constitute a significant fiscal impact” on state regulators who could be reviewing other products, according to the analysis.  

California Gov. Gavin Newsom has until the end of September to sign or veto the law.

This summer, state lawmakers passed a related bill that increases fees on pesticide sales to helped fund enhanced regulatory oversight programs within the state.

Paraquat has been in use for decades as a widely used weedkiller. But a large body of scientific evidence has linked chronic use of the chemical to Parkinson’s disease, which has become a top cause of death in the United States.

Several thousand farmers, agricultural workers and others are suing paraquat maker Syngenta, alleging they developed Parkinson’s because of long-term chronic effects of paraquat, and alleging Syngenta hid the risks from the public and regulators.

The New Lede has previously revealed that Syngenta’s internal research found adverse effects of paraquat on brain tissue decades ago but the company withheld that information from regulators, instead working to discredit independent science linking the chemical to brain disease and developing a “SWAT team” to counter critics.  

“It’s just inconceivable that this herbicide still exists and is widely used in the United States,” California Assemblymember Rick Zbur said in a press conference in April discussing the efforts to ban paraquat. “We should not be widely spraying an herbicide known to cause high blood pressure, heart failure, kidney failure, Parkinson’s disease, childhood leukemia and cancer.”