Scientists and environmental researchers are increasing their focus on 6PPD-Quinone (6PPD-Q), a chemical byproduct formed when the tire additive 6PPD reacts with ozone in the environment, as studies continue to examine its effects on aquatic ecosystems.

6PPD has been widely used in tire manufacturing since the late 1960s as an antioxidant and antiozonant that helps protect tires from cracking and degradation, extending service life and improving performance. However, when tire materials wear down during use, compounds released in tire and road wear particles (TRWP) can transform into 6PPD-Q through atmospheric reactions.

Researchers are studying how these particles move through stormwater systems and into rivers, streams, and other freshwater environments, where the compound has been associated with toxic effects in certain fish species.

Research links 6PPD-Q exposure to aquatic toxicity

Multiple studies have identified 6PPD-Q as highly toxic to coho salmon, with exposure linked to rapid mortality in laboratory and field observations. Researchers have reported that exposure can affect blood vessel integrity and neurological function, leading to severe physiological stress in fish.

Additional field research in waterways connected to urban runoff has found elevated mortality rates among juvenile fish exposed to stormwater containing 6PPD-Q following rainfall events.

These findings have increased scientific and regulatory interest in how tire wear compounds interact with aquatic systems and what mitigation measures may reduce environmental exposure.

Tire wear particles and runoff pathways

The primary pathway under study is runoff from roads, where tire wear particles generated through braking, acceleration, and everyday driving can be carried into drainage systems during rainfall.

Researchers have also examined runoff from artificial turf fields that use crumb rubber infill derived from recycled tires. Studies suggest these surfaces can also contribute 6PPD-Q runoff over time, although heavily trafficked roads are often considered a major source because of larger volumes of tire wear.

This issue connects environmental monitoring with broader discussions around tire recycling, product design, and material lifecycle management.

Treatment and mitigation efforts

Researchers say 6PPD-Q can be treated through filtration and stormwater treatment technologies, and multiple projects are underway to improve runoff capture and treatment systems.

Authorities in Washington have launched several studies and funded stormwater mitigation projects, including filtration upgrades and replacement of crumb rubber infill in some sports fields with alternative materials such as cork or thermoplastic elastomers.

At the same time, regulators and industry stakeholders are examining long-term approaches, including the development of alternative tire additives that can provide similar performance without creating harmful environmental byproducts.

In 2023, the U.S. Environmental Protection Agency began formal work to build a scientific basis for future regulatory decisions related to 6PPD-Q, including development of testing methods to detect the compound in stormwater and surface waters.

Implications for recycling and sustainable materials

The issue also has implications for rubber recycling and circular material development. As the tire industry expands sustainability efforts, researchers are exploring ways to remove or neutralize compounds of concern during recycling and material recovery processes.

In 2024, researchers at University of Delaware reported progress on a chemical extraction method designed to remove 6PPD from tire materials and convert it into potentially safer reusable substances. While the technology remains under development, it may support future advances in tire recycling, cleaner crumb rubber production, and safer material reuse pathways.

As research continues, 6PPD-Q is likely to remain a key topic in discussions around tire chemistry, environmental management, and the future of more sustainable tire materials and recycling systems.

Article source: Jefferson Public Radio.