Department of Ecology
Committees, Boards, and Workgroups

This page is run by the Washington State Department of Ecology and serves as a resource hub for those closely following 6PPD. In addition to this page, we include links to other pages that are relevant to 6PPD below. For more general information about 6PPD, please visit our website. You can also join our email list to receive monthly updates about Ecology's 6PPD work.

What is 6PPD?

In 2020, researchers at the University of Washington-Tacoma, Washington State University, and additional collaborators identified the connection between car tires, 6PPD-quinone, and pre-spawn mortality in coho salmon. In response to this discovery, Washington State is taking action to protect humans and aquatic organisms from these chemicals, including closely monitoring ongoing research and conducting research of our own. 

Informational Resources

• Department of Ecology
  • Alternatives Assessment
    • 6PPD Hazard Assessment (November 2021): reviews existing anti-degradants that could potentially replace 6PPD in tires.
    • 6PPD Alternatives Assessment Hazard Criteria (revised October 2023): provides specific data requirements and standards to assess chemical safety of alternatives to 6PPD.
    • Responsiveness Summary: 6PPD Hazard Criteria (October 2023). The 6PPD Hazard Criteria linked above was revised in response to public input received from June 14, 2023, to July 14, 2023. The responsiveness summary includes this public input and our responses. 
  • Safer Products for Washington 
    • Draft Identification of Priority Chemicals Report to the Legislature: Safer Products for Washington Cycle 2, Implementation Phase 1 (6PPD proposed as a priority chemical)
  • Stormwater
    • 6PPD Stormwater Best Management Practices Research
    • Municipal stormwater permit reissuance (Ecology webpage) 
    • Stormwater Management Manuals: contain guidance for effective 6PPD-q best management practices. Section 1.5: Stormwater Pollutants and Their Adverse Impacts – see “Toxic Organics” and see “Pollutants from Rubber Preservatives (including 6PPD-q).”
      • Emerging Guidance Section: Updated on an ongoing basis to reflect the best 6PPD-q recommendations. Ecology has proposed additional updates to respond to 6PPD as well, to be finalized by August 1, 2024.
    • Stormwater Treatment of Tire Contaminants Best Management Practices Effectiveness (June 2022): best professional judgement on existing BMP options and their likelihood to manage particulate tire wear, 6PPD, and 6PPD-q.
    • Stormwater BMP effectiveness projects (Ecology webpage)
  • Sampling and Monitoring
    • 6PPD in Road Runoff report (October 2022): confirms the complexity of finding 6PPD-q in the environment and identifying the most vulnerable areas
    • 6PPD-q standard operating procedure (June 2023): detailing field sampling and laboratory detection methods. (contact Tanya Williams, tanya.williams@ecy.wa.gov, for a copy)
  • Focus sheets 
    • Focus on: Finding Solutions to 6PPD
    • Focus on: Best Management Practices for 6PPD-q 
    • Focus on: Reducing Sources of 6PPD 
    • Focus on: Monitoring 6PPD-q in the environment
  •  Presentations
    • Part 1 - 6PPD and 6PPD-quinone: Identification of a Problem and the Cause (PowerPoint)
    • Part 2 - 6PPD and 6PPD-quinone: Source Reduction (recorded presentation)
    • Part 3 - Assessing 6PPD-quinone in the Environment (recorded presentation)
    • Part 4 - Stormwater Best Management Practices (recorded presentation)
  • Statewide 6PPD Action Plan 
    • Learn more about the 6PPD Action Plan.
  • Other Ecology project pages
    • Understanding the problem: We are developing methods to test and monitor 6PPD and 6PPD-quinone in the environment so we can identify areas most affected by these chemicals.  Please visit our Evaluating 6PPD in the Environment page to review technical materials related to this work.
    • Reducing sources of 6PPD: Our ultimate goal is to reduce sources of 6PPD-q, which requires finding a safer alternative to 6PPD to use in tires. We will conduct an alternatives assessment to identify possible safer alternatives to replace 6PPD. Please visit our Research and Proposed Alternatives to 6PPD page to review technical materials related to this work.
    • Reducing stormwater pollution: Stormwater best management practices can help reduce the amount of 6PPD-q that makes its way into creeks and streams. Please visit our Stormwater Work Group page to review meeting agendas, notes, and presentations from the 6PPD Subgroup. 
• Department of Health
  • For general questions about human health and 6PPD, contact the Department of Health's Environmental Public Health Division at eha@doh.wa.gov. Tribal inquiries may be directed to the Department of Health's Office of Tribal Public Health and Relations (OTPHR) using otphr@doh.wa.gov. 
  • 6PPD and People's Health
• Department of Transportation
  • WSDOT Stormwater Retrofit
  • WSDOT Stormwater Retrofit: 2023/2024 Prioritization Update Survey123
  • WSDOT Move Ahead Washington Funding & Prioritization Opportunities
• Puget Sound Partnership
  • 6PPD Efforts in Puget Sound
• Other resources
  • Interstate Technology and Regulatory Council (ITRC) Focus Sheet, "What We Know: 6PPD and 6PPD-quinone"

Past Events

Used Tire Lifecycle Study: April 28 from 1:30 to 2:30 PDT

On April 28, Ecology and Eastern Regional Group shared initial results for a Used Tire Assessment in Washington. After presenting their findings, participants had the opportunity to ask questions. You can access the presentation here.

6PPD Webinar: June 21, 2023 from 1 to 3 p.m. PDT

State agencies, including the Department of Ecology, Department of Fish and Wildlife, Department of Health, Department of Transportation, and Puget Sound Partnership prepared materials to share our ongoing work addressing 6PPD and 6PPD-quinone. We invited participants to review informational materials in advance of the event, then submit questions using our online comment form.

During the event, we responded to live questions and questions we received through our comment form. You can read written responses to many of these questions and access resources we shared in our 6PPD interagency webinar follow-up document. 

Webinar Follow-Up Materials

• 6PPD interagency webinar follow-up document
• Written responses to pre-submitted questions

ADA Accessibility

The Department of Ecology is committed to providing people with disabilities access to information and services by meeting or exceeding the requirements of the Americans with Disabilities Act (ADA), Section 504 and 508 of the Rehabilitation Act, and Washington State Policy #188.

To request an ADA accommodation, contact Ecology by phone at 360-407-6700 or hwtrpubs@ecy.wa.gov. For Washington Relay Service or TTY call 711 or 877-833-6341. Visit Ecology’s website for more information.