First determination of elevated levels of plastic additives in finless porpoises from the South China Sea

Plastic additives, such as organophosphate esters (OPEs) and phthalate esters (PAEs), are raising public concerns due to their widespread presence and potential health risks. Nonetheless, the occurrences and potential health risks of these additives in marine mammals remain limited. Here, we first investigated the accumulation patterns and potential risks of OPEs and metabolites of PAEs (mPAEs) in Indo-Pacific finless porpoises inhabiting the northern South China Sea (NSCS) during 2007-2020. The average hepatic concentrations of E15OPEs and E 16mPAEs in the NSCS finless porpoises were 53.9 +/- 40.7 and 98.6 +/- 54.8 ng/g ww, respectively. The accumulation of mPAEs and OPEs in the finless porpoises is associated with the chemical structures of the compounds. E5halogenated-OPEs were the most dominant category (62.6%) of E15OPEs, followed by E6aryl-OPEs (25.9%) and E6nonhalogenated alkyl-OPEs (11.5%). The accumulation of mPAEs displayed a declining trend with increasing alkyl side chain length (C0-C10). Although the hepatic burden of mPAEs in finless porpoises was sex-independent, some OPEs, including TDCIPP, TBOEP, TCIPP, TCrP, TPHP, and TDBPP, exhibited significantly higher concentrations in adult males than in adult females. TDBPP, as a new-generation OPE, exhibited a gradual increase during the study period, suggesting that TDBPP should be prioritized for monitoring in the coastal regions of South China. The estimated hazard quotient indicated that almost all mPAEs and OPEs pose no hazard to finless porpoises, with only DEHP presenting potential health risks to both adult and juvenile finless porpoises.