The Department of Toxic Substances Control (DTSC) in California has implemented a rule that requires producers of vehicle tires for sale in the state to investigate safer alternatives to the chemical 6PPD which is used by manufacturers to reduce tire cracking and enhance service life.
The ruling was adopted to protect public and environmental health, and comes as 6PPD has been found to react with ozone in the air, resulting in 6PPD-quinone. Traces were discovered in California’s streams, with the chemical found to kill coho salmon as the species migrates upstream to spawn.
DTSC’s regulation to add vehicle tires containing 6PPD to California’s list of Priority Products, which was initially proposed in 2022, will come into effect on October 1, 2023. The DTSC has also announced that domestic and foreign manufacturers must let the department know by November 30 if the tires that they produce for the Californian market contain 6PPD.
The department is working in collaboration with the US Tire Manufacturers Association (USTMA) to guide tire manufacturers through the new process.
“We are working with the US EPA, other states, researchers and the Tire Manufacturers Association to find a path to make tires safer for our environment without compromising on-road safety,” said Dr Meredith Williams, director, DTSC.
The new regulation come after scientists in the US Pacific Northwest linked 6PPD from vehicle tires with coho salmon deaths. The confirmed presence of 6PPD-quinone in the state’s waterways has resulted in the salmon species now being classified as endangered or threatened.
“DTSC’s Alternatives Analysis process requires manufacturers to identify and compare the impacts of potential alternatives with those of the Chemical of Concern across a product’s life cycle,” explained Karl Palmer, deputy director, DTSC.
“6PPD plays a crucial role in the safety of tires on California’s roads and, currently, there are no widely available safer alternatives. For this reason, our framework is ideally suited for identifying alternatives to 6PPD that ensure the continued safety of the tires on California’s roads while protecting California’s fish populations and the communities that rely on them.”