What is 6PPD and Why Is It Making Headlines?

Emerging Contaminant: 6PPD

If you’ve been following environmental news, you may have seen the term 6PPD popping up in discussions among regulators, scientists, and advocacy groups. But what exactly is 6PPD, and why is it drawing so much attention?

What Is 6PPD?

Chemically known as N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine, 6PPD is an antioxidant and antiozonant widely used in the rubber industry—especially in vehicle tires. Its primary role is to protect rubber from cracking and degradation caused by ozone and other reactive oxygen species in the atmosphere.

This protection is critical for tire safety and longevity, preventing premature failure under environmental stressors such as UV exposure and flex fatigue. Beyond tires, 6PPD is also used in other rubber products to extend their service life. Originally developed in the 1960s, it became widely adopted in the 1970s and remains common today.

Why Is 6PPD an Emerging Contaminant?

When 6PPD reacts with ozone, it forms 6PPD-quinone (6PPD-Q)—a compound now recognized as a contaminant of emerging concern. Tire wear releases particles containing 6PPD and 6PPD-Q into the environment, often through roadway runoff during rain events.

Research shows that 6PPD-Q can be toxic to certain aquatic species at concentrations found in stormwater runoff. It has been detected in waterways, sediments, and even human biological samples, prompting significant scientific and regulatory attention.

Regulatory agencies, including the U.S. Environmental Protection Agency (EPA), have initiated actions under the Toxic Substances Control Act (TSCA) to gather data on 6PPD and its transformation products. An Advance Notice of Proposed Rulemaking (ANPRM) was issued to solicit information on environmental fate, exposure pathways, toxicity, and potential alternatives.

What Are Stakeholders Saying?

Public discourse around 6PPD reflects growing concern about its ecological impact, particularly on salmon populations in the Pacific Northwest. Tribal nations, environmental groups, and industry stakeholders are actively engaged in discussions about mitigation strategies, regulatory frameworks, and research priorities.

While there is consensus on the need for more data, opinions vary on the pace and scope of potential regulatory actions. Tire manufacturers emphasize that 6PPD is critical for tire safety because it prevents cracking and degradation. Without it, tire integrity would be compromised, posing a serious safety risk for motorists. Currently, there is no commercially available alternative that meets federal performance and durability standards, though a consortium of manufacturers is working to identify potential options.

How RJ Lee Group Can Help

Based on decades of experience assisting clients with emerging contaminant concerns, we strongly recommend against a “wait-and-see” approach. If future 6PPD regulations could affect your operations, now is the time to establish a baseline so you know where you stand.

Our capabilities include:

• Raw Material Analysis
  Testing rubber compounds, additives, and other raw materials for 6PPD and related compounds.

• Finished Goods Testing
  Comprehensive analysis of tires and other rubber products to ensure compliance readiness and support product stewardship.

• Soil and Water Assessment
  Detecting trace levels of 6PPD and 6PPD-Q in environmental samples, providing defensible data for stormwater, runoff, and site investigations.

• Alternative Evaluation
  Characterizing new materials, validating performance, and assessing environmental impact as the industry explores substitutes for 6PPD.

Our fixed laboratories deliver high-precision results, while our mobile labs bring advanced instrumentation—such as PTR-TOF-MS and AIMS—directly to your site for real-time monitoring. This combination ensures rapid turnaround, actionable insights, and compliance support wherever you operate.

Looking Ahead

The conversation around 6PPD underscores the importance of proactive monitoring and collaborative research. As regulations evolve and scientific understanding deepens, RJ Lee Group remains committed to supporting clients with cutting-edge technology and expert guidance.

Contact us today to learn how we can help you prepare for potential 6PPD regulations.

References

1. EPA: https://www.epa.gov/chemicals-under-tsca/6ppd-and-6ppd-quinone
2. Tian et al., Science of the Total Environment: https://www.sciencedirect.com/science/article/pii/S004896972100993X
3. Panko et al., Environmental Science & Technology: https://pubs.acs.org/doi/10.1021/acs.est.1c00910
4. Federal Register: https://www.federalregister.gov/documents/2023/11/02/2023-24241/6ppd-and-6ppd-quinone-request-for-information
5. Washington State Ecology: https://ecology.wa.gov/Regulations-Permits/Guidance-technical-assistance/Stormwater/6PPD-quinone