Emerging tire additives and their quinone derivatives in marine species: Characteristics, sources, and health risks

p-phenylenediamines (PPDs), effective rubber antioxidants, and their derived quinones (PPDQs) are prevalent in the environment. However, limited data are available regarding their presence in marine species and associated health risks. In this study, we analyzed seven common PPDs and five related PPDQs in marine fish and shellfish from Pearl River Delta coastal waters, investigating contamination emission sources and assessing associated human health risks. The results revealed that concentrations of Σ₇PPDs and Σ₅PPDQs ranged from 45.65 to 3168.14 pg/g wet weight (ww) and 14.09 to 1491.29 pg/g ww, respectively. Distinct profiles were observed in marine organisms, with N,N'-Bis(1,4-dimethylpentyl)-p-phenylenediamine (77PD, 104.03 pg/g ww) dominating the PPDs and 2-[(1-Methylethyl)amino]-5-(phenylamino)-2,5-cyclohexadiene-1,4-dione (IPPDQ, 78.66 pg/g ww) prevailing in the PPDQs, contrasting with patterns reported in environmental matrices. Absolute principal component scores-multivariate linear regression and positive matrix factorization models identified industrial and domestic emission sources as the predominant contributors to PPD and PPDQ contamination in marine organisms. Estimated dietary intakes through seafood consumption among adolescents and adults ranged from 0.03 to 3.31 ng/(kg·day) for Σ₇PPDs and 0.01 to 1.56 ng/(kg·day) for Σ₅PPDQs, respectively. No apparent non-carcinogenic health risks were identified for residents consuming marine organisms contaminated with PPDs. This study underscores the imperative of monitoring emerging contaminants in seafood, as these pollutants may pose latent risks to human health through dietary intake.