Comprehensive review on environmental pollution caused by 6PPD-quinone and remediation strategies
Sivakumar Sivalingam, Jayagopi Gayathri, G. Boopathy, Dongjin Choi, Kumar Sangeetha Selvan · 2026 · 11 citationsRead the paper
-phenylenediamine-quinone) due to tyre wear and is emitted along with road particles into the air, resulting in a severe impact on the environment. It has been found that 6PPD increases the mortality rate of silver salmon, an aquatic fauna having rich omega-3 fatty acid content and many essential nutrients. Further, this 6PPD-quinone affects higher organisms by entering the aquatic food chain. Hence, this bioaccumulation severely affects the top predators, including humans. The scientific and regulatory bodies are working hard to find a safer alternative to 6PPD to eradicate the environmental pollution due to 6PPD-Q, a degradation product of 6PPD. The current review article addresses the various approaches to reducing 6PPD release in the environment, removing the existing 6PPD from the surrounding environment, and finding a safer alternative to 6PPD to increase the tyre lifetime. Remediation strategies involve potential substitutes for 6PPD and 6PPD-Q, including alternative PPDs such as IPPD, DPPD, 7PPD, and CCPD, as well as non-PPD options like specialized graphene, octyl gallate, lignin, and nano-calcium carbonate modified with gallic acid. These candidates offer protection against ozone, oxidation, and wear while maintaining tire performance and safety. In addition, the review provides details on potential alternatives and the mechanisms through which they protect the environment. The existing knowledge gaps and directing researchers in establishing research in the various fields to protect against this kind of pollution.
What the full text shows
Shown in the lab- 6PPD-quinone (6PPD-Q) causes acute mortality in coho salmon. — LC50 of 80.4 ng L−1 (12 h exposure) (In vivo coho salmon)
- UV-activated peroxymonosulphate (UV/PMS) system achieves complete degradation of 6PPD-Q. — 100% degradation at 1:60 ratio of 6PPD-Q to PMS (Aquatic environment)
- Environmental levels of 6PPD-Q are sufficient to be toxic to coho salmon. — 95 ng L−1 (Environmental estimate)
- Chinook salmon exhibit lower sensitivity to 6PPD-Q than coho salmon. — Sensitive at concentrations >25 µg L−1 (approx. 10x environmental levels) (In vivo)
- Rainbow trout cells exhibit metabolic effects from 6PPD-Q. — EC50 of 68 µg L−1 (In vitro RTG-2 cells)
- 77PD exhibits rapid hydrolysis compared to water. — 181-fold higher rate (half-life of 5.3 h at pH 7) (Environmental air or water)
- Setup
- Review of in vivo and in vitro studies (including CSE-119, CHSE-214, and SSE-5 cell lines) and chemical property analyses of PPD and non-PPD alternatives.
- How
- The paper is a comprehensive review analyzing existing literature on 6PPD/6PPD-Q toxicity, remediation techniques (adsorption, oxidation, green infrastructure), and potential chemical alternatives for tire manufacturing.
- Limitations
- Ecotoxicity of intermediate by-products from UV/PMS degradation is not fully understood. · Biochar adsorption efficiency varies based on pH, type, and dosage. · Octyl gallate lacks long-lasting protection under UV radiation. · Uncertainty in measuring hydrolysis and absorption rates of 77PD.
Summarized by Gemma 4 from the open-access full text · 8 Oct 2026. Read it