California begins paraquat phase-out after manufacturer withdrawals

California is beginning a phase-out of the widely used herbicide paraquat after all manufacturers withdrew their product registrations rather than submitting required health and safety data to state regulators. The California Department of Pesticide Regulation announced the move following a June 5 deadline for companies to provide scientific data to address gaps in the human health toxicology database.

Preliminary scientific assessments by the state identified potential links between paraquat exposure and thyroid impacts, birth defects, and risks to birds. While the phase-out is underway, licensed dealers may continue to sell existing stock for up to two years following each product's cancellation, meaning the chemical could remain in commerce in California until 2028.

The decision follows growing health concerns, as studies have associated the chemical with Parkinson’s disease. While environmental advocates and some state regulators push for its removal, many farmers argue the herbicide is an essential tool for managing weeds and preventing soil erosion. Syngenta, one of the major producers, previously announced it would stop producing the chemical following numerous lawsuits, though the company has maintained that claims linking the product to illnesses are meritless.