Accumulation, toxicity, and underlying mechanisms of short-chain chlorinated paraffins in early life stages of Chlamys farreri

Abstract

Short-chain chlorinated paraffins (SCCPs) have attracted extensive attention due to their wide distribution and associated human exposure risks. Although marine bivalves exhibit a high accumulation capacity for SCCPs, their toxicological effects and underlying mechanisms remain poorly understood. To address this, the accumulation, toxicity, and molecular mechanisms of SCCPs were evaluated by using Chlamys farreri as model animals and exposing them to three concentrations (2, 20, and 100 μg/L) for 30 days. The results suggested that SCCP accumulation was more pronounced in scallops with smaller shell length. Throughout the exposure period, the relative abundance of C 10 -C 13 congeners remained nearly consistent, with Cl 6–8 identified as the major homologues. Exposure to 20 and 100 μg/L SCCPs induced notable developmental toxicity in scallops, including malformations, increased mortality rate, and decreased development rate. Oxidative stress, histopathological damage, and disruption of endocrine-related indicators were also observed in gill tissues of juveniles. Transcriptomic and metabolomic analyses collectively revealed that SCCP toxicity might be attributed to oxidative stress and disturbance in the metabolism of fatty acids, phospholipids, amino acids, and nucleotides. Excessive consumption of lipids and suppression of biomacromolecule synthesis appeared to jointly contribute to the growth retardation of scallops. This study provides novel insights for evaluating the potential effects of SCCPs on marine organisms and ecosystems.