A piece of the ecotoxicology puzzle: how can current and future research inform PPD regulations?

2-((4-Methylpentan-2-yl)amino)-5-(phenylamino)cyclohexa-2,5-diene-1,4-dione commonly known as 6PPD-Quinone (6PPD-Q), is the ozonized derivative of, N-(1,3-dimethylbutyl)-N’-phenyl-p-phenylenediamine, 6PPD. 6PPD is a common tire coating that prevents rubber degradation by acting as an antioxidant. Research efforts elucidating 6PPD-Q’s toxicity surged after a 2021 study identified 6PPD-Q as an acute mortality inducing toxicant to coho salmon. This commentary functions as a compilation of 6PPD and 6PPD-Q’s interaction with aquatic and terrestrial organisms. We also encompass studies providing toxicological explanations of dysregulation of intracellular activity and metabolite transformation. We aim to concurrently impart an overview of the most current 6PPD and 6PPD-Q studies at organismal and cellular levels, emphasize research gaps, such as the lack of global regulations, and propose possible routes for future studies, like the expansion into different model organisms, lifecycle effects, fertility and transgenerational effects, and cancer cell studies.