Occurrence, maternal transfer, and risk implications of parabens in humpback dolphins from the South China Sea

Parabens (PBs), extensively used as preservatives in food, cosmetics, and pharmaceuticals, are increasingly detected across diverse environmental matrices. Nevertheless, their presence and potential impacts on marine apex predators remain poorly understood. Here, hepatic tissues from 87 Indo-Pacific humpback dolphins collected from the northern South China Sea (NSCS) during 2004-2021 were analyzed for four PBs and five paraben metabolites (m-PBs) to investigate their bioaccumulation characters and potential health risks. Five target compounds were detected, with their total concentrations (4840 ± 4120 ng/g ww) comparable to those of persistent organic pollutants previously detected in this species. All five PBs/m-PBs demonstrated transplacental transfer potential, with OH-MEP showing the highest transfer efficiency (45.78 %). Risk assessment revealed that hepatic methylparaben concentrations in over 45 % of the non-calf dolphins exceeded the estimated hepatic toxicity thresholds. Furthermore, the observed increasing time trends of methylparaben levels suggest that the NSCS humpback dolphin populations may suffer long-lasting high risks in the future. These findings provide the initial evidence of the PB/m-PB occurrence and associated health risks in the NSCS dolphins and underscore the urgency of mitigating paraben contamination in South China.