6PPD-Quinone

6PPD-Quinone – At a Glance

6PPD is a chemical currently used in tires to protect the rubber in the tire from degrading and make the tire last longer. Concerns have been raised about the breakdown of 6PPD when it reacts with ozone and forms 6PPD-quinone (6PPD-Q). 6PPD-Q can enter streams and water bodies and have potential environmental impacts.

The National Toxicology Program (NTP), in coordination with the National Science and Technology Council (NSTC) Joint Subcommittee on Environment, Innovation and Public Health (JEEP), has formed a work group to coordinate federal efforts related to the potential human health effects of 6PPD-Q.

Background

6PPD [N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine] is a chemical currently used in tire production to protect tire rubber from degrading due to reactions with ozone and other reactive oxygen species in the air. This antioxidant helps prevent tires from forming cracks and deteriorating when exposed to sunlight and other environmental factors. When 6PPD reacts with ozone, it forms the transformation product 6PPD-Q.

As vehicles travel, their tires undergo constant wear and tear resulting in the release of tiny tire-wear particles, and when it rains, stormwaters can wash these particles into streams and other water bodies. As a result, aquatic species can be exposed to 6PPD and 6PPD-Q. Concerns have been raised specifically about contamination from 6PPD-Q and its potential environmental impact. Coho salmon seem to be exceptionally sensitive to the toxic effects of 6PPD-Q. Tian et al. (2021) showed that 6PPD-Q was present in runoff at levels high enough to cause death among juvenile coho salmon and explain acute mortality events in the Pacific Northwest.

While additional research is needed to address 6PPD-Q in the environment, a key area is whether 6PPD-Q exposure has adverse effects on human health.

Work Group

In early 2023, the White House Office of Science and Technology Policy’s NSTC JEEP identified 6PPD-Q as an emerging contaminant that would benefit from coordination across federal agencies. In response to this outreach, the NTP formed a work group as a focal point for federal efforts related to 6PPD-Q. While the work group has a focus on understanding the effects on human health, the coordination effort is broad reflecting the diversity of activities and interests of the participating agencies with broader expertise including ecotoxicological and environmental exposure science.

Work Group Objectives

The role of the work group is to facilitate coordinated efforts and information sharing about research and other activities occurring across the federal government related to 6PPD-Q and associated chemicals. The NTP hopes this information sharing will raise awareness about the extent of federal research, identify activities that are complementary, reduce duplicative effort, and focus research on key data needs that will advance scientific understanding around any potential adverse human health effects of 6PPD-Q exposure.

6PPD-Q Literature Portals, Data Resources, Publications, and Other Resources

These portals and resources include scientific literature and information related to 6PPD-Q that appear in PubMed and other databases. These can be used by the research community and members of the public.

Literature Search Portals

Data Resources/Publications

Other 6PPD-Q and related chemicals resources

Presentations
Select Publications of Work Group Members
  • Brown, M. L., Ivy, N., Gonzalez, M., Greer, J. B., Hansen, J. D., Kolodziej, E., & McIntyre, J. K. (2026). Roadway runoff induced acute mortality in juvenile coho salmon during spring storm events. Environmental Science & Technology. https://doi.org/10.1021/acs.est.5c13992.
  • Greer, J. B., Dalsky, E. M., Bachand, P., Hansen, J. D., & Manahan, C. (2026). Toxicity of 6PPD alternatives to salmonid cell lines. Washington Department of Ecology. https://pubs.usgs.gov/publication/70273838.
  • Harris, F. R., Jankowski, M. D., Villeneuve, D. L., & Harrill, J. A. (2025). Phenotypic Profiling of 6PPD, 6PPD-Quinone, and Structurally Diverse Antiozonants in RTgill-W1 Cells Using the Cell Painting Assay. Environmental Science & Technology Letters, 12(6), 695-701. https://doi.org/10.1021/acs.estlett.5c00327.
  • Jankowski, M. D., Carpenter, A. F., Harrill, J. A., Harris, F. R., Hill, B., Labiosa, R., ... & Villeneuve, D. L. (2025). Bioactivity of the ubiquitous tire preservative 6PPD and degradant, 6PPD-quinone in fish-and mammalian-based assays. Toxicological sciences, 204(2), 198-217. https://doi.org/10.1093/toxsci/kfaf008.
  • Jarvis, A., Prossner, K., Schnitker, B., & Gallagher, K. (2025). Derivation of acute aquatic life screening values for 6PPD and 6PPD-quinone in freshwaters by USEPA Office of Water. Environmental Toxicology and Chemistry, 44(11), 3109-3117. https://doi.org/10.1093/etojnl/vgaf189.
  • Rachael F. Lane, Kelly L. Smalling b, Paul M. Bradley, Justin B. Greer, Stephanie E. Gordon, John D. Hansen, Dana W. Kolpin, Andrew R. Spanjer, Jason R. Masoner. Tire-derived contaminants 6PPD and 6PPD-Q: Analysis, sample handling, and reconnaissance of United States stream exposures. Chemosphere. https://doi.org/10.1016/j.chemosphere.2024.142830
  • Lane, R.F., Smalling, K.L., Bradley, P.M., Tush, D.L., Dietze, J.E., Greer, J.B., Hansen, J.D., Spanjer, A.R., Lucena, Z.N., Masoner, J.R., Stack, J.K., Sinclair, D.A., Johnson, A.G., Riskin, M.L., and Lambert, M.R., 2024, Concentrations of 6PPD and 6PPD-Quinone in a United States reconnaissance of stormwater, surface water, and groundwater, 2018-24: U.S. Geological Survey data release, https://doi.org/10.5066/P1A6RSGW.
  • Moody, A. H., Soucek, D. J., & Alvarez, D. A. (2025). Targeted quantitation of 6PPD-quinone in fish tissue samples with liquid chromatography–tandem mass spectrometry. Environmental Toxicology and Chemistry, 44(10), 2807-2817. https://doi.org/10.1093/etojnl/vgaf151.
  • Nyffeler, J., Harris, F. R., Willis, C., Byrd, G., Blackwell, B., Escher, B. I., ... & Harrill, J. A. (2025). A combination of high-throughput in vitro and in silico new approach methods for ecotoxicology hazard assessment for fish. Environmental Toxicology and Chemistry, 44(9), 2599-2621. https://doi.org/10.1093/etojnl/vgae083.
  • Seo, J. E., Li, X., Le, Y., Mei, N., Zhou, T., & Guo, X. (2023). High-throughput micronucleus assay using three-dimensional HepaRG spheroids for in vitro genotoxicity testing. Archives of toxicology, 97(4), 1163-1175. https://doi.org/10.1007/s00204-023-03461-z.
  • Shankar, P., Dalsky, E. M., Salzer, J. E., Lane, R. F., Hammond, S., Batts, W. N., ... & Hansen, J. D. (2025). Evaluation of 6PPD-quinone lethal toxicity and sublethal effects on disease resistance and swimming performance in coastal cutthroat trout (Oncorhynchus clarkii clarkii). Environmental Science & Technology, 59(23), 11505-11514. https://doi.org/10.1021/acs.est.5c03697.
  • Soucek, D. J., Dorman, R. A., Candrl, J. S., Moody, A. H., Lane, R. F., Greer, J. B., ... & Steevens, J. A. (2026). Time course of effects and tissue concentrations of 6PPDQ in three sensitive salmonids with additional data for two centrarchid species. Environmental Science & Technology, 60(8), 6002-6010. https://doi.org/10.1021/acs.est.5c12991.
  • Soucek, D. J., Dorman, R. A., Steevens, J. A., Yargeau, V., Pineda, M., Bennett, E. R., & Metcalfe, C. D. (2025). Acute Toxicity of 4-hydroxydiphenylamine (4-HDPA) and N-(1, 3-dimethylbutyl)-N'-phenyl-p-phenylenediamine-quinone (6PPDQ), transformation products of 6PPD, to early instars of the mayfly, Neocloeon triangulifer. Environmental Toxicology and Chemistry, 44(5), 1369-1377. https://doi.org/10.1093/etojnl/vgaf062.
  • Yeisley, D. J., Ren, L., Papineau, K. S., Schnackenberg, L. K., da Costa, G. G., Patterson, T. A., ... & Shi, Q. (2025). Toxicity of ubiquitous tire rubber antiozonant N-(1, 3-dimethylbutyl)-N′-phenyl-p-phenylenediamine (6PPD) and its transformation product 6PPD-quinone (6PPD-Q) in primary human hepatocytes and liver spheroids. Biochemistry and Biophysics Reports, 43, 102199. https://doi.org/10.1016/j.bbrep.2025.102199.
Other Presentations and Publications of Interest
  • Presentation at the 2025 ITRC Training Webinar:
  • Halama, J. J., McKane, R. B., Barnhart, B. L., Pettus, P. P., Brookes, A. F., Adams, A. K., ... & Kolodziej, E. P. (2024). Watershed analysis of urban stormwater contaminant 6PPD-Quinone hotspots and stream concentrations using a process-based ecohydrological model. Frontiers in environmental science, 12, 1364673. https://doi.org/10.3389/fenvs.2024.1364673.
  • Tian, Z., Zhao, H., Peter, K. T., Gonzalez, M., Wetzel, J., Wu, C., ... & Kolodziej, E. P. (2021). A ubiquitous tire rubber–derived chemical induces acute mortality in coho salmon. Science, 371(6525), 185-189. https://doi.org/10.1126/science.abd6951.

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