Washington lawmakers are considering a bill (SB 6119/HB 2421) that would protect the health of salmon and people by banning toxic 6PPD in motor vehicle tires, creating a practical, science-based path toward innovation and safer solutions.
The science is settled on the extreme hazard of 6PPD
6PPD is widely used as an additive in rubber products, including motor vehicle tires. Among other paths, it enters our waterways through tire dust in run-off from roads. In the process, it readily transforms to the toxic 6PPD-quinone (6PPD-Q), notorious for causing the death of young salmon. The problem is so severe that scientists, led by those at the University of Washington and Washington State University, created a term to refer to pre-spawn mortality of salmon and general aquatic toxicity as a result of 6PPD-Q exposure: urban runoff mortality syndrome (URMS).
6PPD is one member of the class of chemicals known as para– or p-phenylenediamines, or PPDs. PPD and PPD derivatives like 6PPD can directly harm our health, too. 6PPD can act as a skin sensitizer, meaning it can cause adverse effects on the skin. Emerging evidence suggests 6PPD-Q is associated with additional adverse health outcomes, including reproductive toxicity. Moreover, the Environmental Protection Agency (EPA) has designated 6PPD as a High Production Volume chemical, meaning it is produced or imported into the United States annually in amounts of at least 1,000,000 pounds.
The costs of 6PPD are exorbitant
Washington state has been spending tens of millions of dollars on the 6PPD problem, conducting research studies and carrying out mitigation, among other efforts. For example, the Legislature approved more than $500 million over 16 years for retrofits intended to mitigate the effects of stormwater pollutants such as 6PPD.
Sick and tired of 6PPD: the road ahead
Due to the urgency of the environmental health crisis caused by 6PPD, Washington lawmakers are considering SB 6119 (Senator Liias-D, Edmonds)/HB 2421 Rep. Hall D-Issaquah), an innovative bill that would restrict 6PPD and regrettable 6PPD substitutes in tires. The bill provides adequate time for innovation and compliance, prohibiting 6PPD in tires by 2035. The bill also includes a fee on tires.
The nine-year timeline proposed by this bill allows more than enough time for the industry to test any alternative chemicals to ensure they are truly safer, and to conduct performance testing in tires.
The provision in the bill that also bans regrettable substitutes is critical. We are concerned that the tire industry is considering moving to 7PPD, which would be a bad option. There is nothing that prevents the industry from moving to this concerning chemical, or other regrettable substitutes, without action from the legislature.
This bill is critical to salmon health, human health, and ecological health; sensitive populations and aquatic ecosystems are especially threatened by 6PPD. Please support this bill and take action here.
Science Director
Ryan Babadi joined Toxic-Free Future in May 2025 as Science Director, bringing his expertise in environmental epidemiology, toxicology, and data science.
Director of Government and Market Policy
Cheri Peele joined Toxic-Free Future in 2022 to play a leadership role in both the Retailer Report Card and public policy advocacy. She has worked for over 20 years to create and implement leadership strategies for the transition to safer chemicals.
