Unraveling Hidden Toxic Potential of 6PPD-quinone: A New Threat to Environment and Human

Tire wear particles (TWP) are responsible for emitting around 0.23 to 1.90 kg of contaminants per year worldwide thus demanding high attention because of their huge detection, high toxicity, small size and mobility. Among these, N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine quinone (6PPD-Q), released by the oxidation of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD) due to its acute toxicity, highlighted as an evolving pollutant of major concern. They can be found in sediment water, soil, dust and air, globally, signifying their meaning as emerging contaminant. Despite increased interest in 6PPD-Q, considerable knowledge gaps persist, particularly about its long-term toxicity, environmental fate, bioaccumulation mechanisms, and chronic exposure consequences in both wildlife and humans. This review analyzes the molecular structure, physicochemical properties, production mechanisms, environmental occurrence, and toxicological effects of 6PPD-quinone. It also assesses the feasibility and current stage of development of current mitigation strategies, such as microbial biodegradation, alternative tire additives, and photocatalytic degradation. The paper further highlights different industrial and biomedical applications of 6PPD-Q and its toxicity to human and environment. The study further deals with regulatory framework, current regulations, future regulatory trends, research and innovation and collaborative research efforts that are still demanded, even though interested in this topic, there are still gaps in research for reducing the deleterious effects of 6PPD-Q on environment and society.