On June 10, the U.S. Environmental Protection Agency (EPA) released water quality screening values under the Clean Water Act concerning short-term concentrations of 6PPD and 6PPD-quinone (6PPD-q). These chemicals, linked to runoff from automotive tire dust and debris, have been found in freshwater ecosystems and are known toxins that can cause fish-kill events.
The EPA's non-regulatory and non-binding screening values provide information that tribes, states, and local governments can use to monitor their waterways and help protect aquatic life from these harmful pollutants. "Achieving clean water that protects aquatic life and supports commercial, recreational, and cultural fishing practices takes partnership at all levels of government," said EPA Acting Assistant Administrator for Water Bruno Pigott. "6PPD and 6PPD-q can be lethal to fish, so it’s important we know where it’s polluting waterways. The EPA’s screening values provide important information that our partners can use to protect fish populations—especially coho salmon on the Pacific coast. Solutions like stormwater treatment and green infrastructure are effective at reducing concentrations of these chemicals in freshwater ecosystems."
This announcement is part of a series of actions by the EPA aimed at understanding and reducing freshwater aquatic life exposure to these harmful chemicals. In November 2023, the agency committed to considering regulations prohibiting the manufacturing, processing, use, and distribution of 6PPD in tires. It also announced its intent to publish an advanced notice of proposed rulemaking under the Toxic Substances Control Act (TSCA). Additionally, plans were revealed to finalize a rule requiring manufacturers (including importers) of 6PPD to report lists and copies of unpublished health and safety studies to the agency.
In January 2024, the EPA published a draft testing method to assist tribes, states, and key stakeholders in determining where and when 6PPD-q is present in local stormwater and surface waters. By March 2024, investments were announced in Washington state aimed at treating and controlling stormwater runoff containing 6PPD and 6PPD-q.
The EPA's screening values are based on current scientific knowledge about the short-term toxicity of 6PPD and 6PPD-q to freshwater aquatic life. According to current science, concentrations of these chemicals at or below the recommended screening values are likely to protect freshwater aquatic life. However, these recommended screening values do not impose any legally binding requirements.
Learn more about the EPA’s screening values for 6PPD and 6PPD-q as well as other related work.
