Environmental protection Agency
November 26, 2024
Vehicle tires contain the chemical known as 6PPD to prevent tires from breaking down due to reactions with ozone and other reactive oxygen species in the air. When 6PPD reacts with ozone in the air, it forms 6PPD-quinone. Tires wear down through contact with roads, releasing particles into the environment. When it rains, stormwater from hard surfaces like parking lots and streets washes these particles into streams and other water bodies. As a result, 6PPD-quinone may be present and aquatic organisms can be exposed to it.
Available information on 6PPD-quinone indicates that it is toxic enough to quickly kill some fish. A 2021 publication in the journal Science linked coho salmon death to 6PPD-quinone in stormwater. Concentrations in stormwater were found to be lethal for coho salmon following exposures lasting only a few hours. Subsequent work identified some other fish species as vulnerable to 6PPD-quinone.
The potential of 6PPD-quinone to have ecotoxic effects and impact salmon populations is a key issue. These fish species have cultural, commercial, and ecological importance, and some coho salmon populations are endangered and threatened. Many Tribes rely heavily on salmon and other aquatic resources for food and cultural practices. Healthy and accessible salmon populations are critical to the health and wellbeing of Tribes, including the practice and protection of Tribal Treaty Rights.
Limited information is available regarding emissions, fate and transport, and human health effects of 6PPD-quinone. Research regarding promising stormwater treatment options, such as engineered green infrastructure systems, is ongoing. EPA’s researchers and partners across the country are working hard to address these information gaps about 6PPD-quinone. This information will help EPA and state, local, and Tribal partners make more informed decisions on how best to protect human health and the environment.