Unexpected Exposure Risks to Emerging Aromatic Amine Antioxidants and p-Phenylenediamine Quinones to Residents: Evidence from External and Internal Exposure as Well as Hepatotoxicity Evaluation

Aromatic amine Antioxidants (AAs), extensively used in rubber products, and their ozone-photolyzed product p-phenylenediamine Quinones (PPD-Qs) were found to be pervasive in various environments and with potential ecological and health risks. The relationship between external and internal exposure to these contaminants and their exposure risks to the general population remain poorly explored. Herein, dust-handwipe-urine samples (n = 97 pairs) from families in Tianjin, China was collected for analyzing 20 AAs and 6 PPD-Qs (including self-synthesized emerging PPD-Qs). The median concentration of ∑₂₀AAs (1310 ng/g, 354 ng/m², and 18.5 ng/mL, respectively) and ∑₆PPD-Qs (1645 ng/g, 3913 ng/m² and 3.76 ng/mL, respectively) in dust, handwipe, and urine samples indicated a non-negligible contamination of AAs and PPD-Qs in indoor environment. Notably, emerging DPPD-Q and DNPD-Q (oxidation products of DPPD and DNPD, respectively) were prominent, accounting for >90% of PPD-Qs. The correlation analysis and estimated daily intake (EDI) assessments indicated that neither dust ingestion nor dermal exposure may be the primary source of internal exposure to AAs and PPD-Qs in the general population, and Other exposure pathways (e.g., diet and inhalation) may exist. In vitro HepG2 cell experiments demonstrated that both PPD-Qs and PPDs may have potential exposure risk of hepatotoxicity.