USTMA supports listing 6PPD in tires as a priority product for review

Washington, DC – The U.S. Tire Manufacturers Association (USTMA) announced that it supports the proposed rulemaking released by the California Department of Toxic Substances Control (DTSC) to designate 6PPD in automobile tires as a priority product for review under the state’s Safer Consumer Products green chemistry program.
USTMA and its member companies recommended adding 6PPD to the Priority Products Work Plan immediately following the December 2020 Tian et al. study that suggested a link between Coho salmon mortality and a transformation product of 6PPD from tire and road wear particles (TRWP) called 6PPD-Quinone. Tire manufacturers have taken seriously the Tian et al. study and more recent scientific findings which indicate that 6PPD-Quinone, a previously unknown transformation product of 6PPD – an essential antioxidant and antiozonant used in tires – has contributed to the mortality of coho salmon and potentially poses risks to other aquatic species in the Pacific Northwest.
“USTMA supports the decision by the California DTSC to list 6PPD as a priority product under the state’s green chemistry program,” said USTMA President and CEO Anne Forristall Luke. “USTMA members are committed to producing the safest, most durable and most efficient tires possible. This is why we made the request to the DTSC to list 6PPD as a priority product a few weeks after the release of the Tian et al. study – and why we have been working with the agency and many other stakeholders ever since. We are fully committed to continuing to work with the DTSC team to find a viable alternative.”
Since the release of the Tian et al. study 18 months ago, USTMA has worked with researchers, regulators and legislators to more fully understand the implications of these findings and to seek solutions, including: filling research gaps around 6PPD-Quinone; advocating for a 6PPD alternatives analysis in California; and supporting mitigation efforts to treat stormwater runoff.
The tire industry uses 6PPD, an antioxidant and antiozonant that prevents tires from cracking and failing to help tires resist degradation, which is vital for passenger safety. Any viable alternative to 6PPD in tires must provide the same critical protection as 6PPD to ensure driver and passenger safety. Importantly, any potential substitute must also avoid any regrettable environmental impacts of its own.
“We are pleased that there have been many advancements in the body of research on 6PPD-Quinone,” said Sarah Amick, Vice President of EHS&S and Senior Counsel for USTMA. “However, many data gaps still remain, so we remain committed to collaborating with researchers, regulators and stakeholders to fill these knowledge gaps and help find a viable alternative to 6PPD that does not compromise tire performance or driver safety and also ensures environmental safety.”
Additionally, recognizing the challenges associated with the study of TRWP – a source of 6PPD-Quinone in the environment – USTMA announced in November 2021 it is producing cryogenically milled tire tread (CMTT) and making samples available to researchers to advance ongoing studies.
As global leaders in manufacturing, USTMA member companies embrace a shared responsibility of helping to achieve a more sustainable society. Tire manufacturers are dedicated to understanding and reducing the environmental impact of their products. USTMA members — both individually and through partnerships — are working to incorporate more renewable and recycled materials into tires, enhancing biodiversity and reducing dependence on non-renewable feedstocks.
While continued research is underway, USTMA supports the increased implementation of bioretention technologies, such as raingardens and bioswales, which have been proven to reduce the impact of 6PPD-Quione on coho salmon.