Distribution and exposure risk assessment of short- and medium-chain chlorinated paraffins in marine organisms from the North Yellow Sea of China

The ocean is a treasure trove of resources that supports future development and a strategic space. Protecting marine resources is crucial for economic development and food security. As a sink for terrestrial pollutants, it is urgent to conduct surveys and research on the distribution characteristics and risks of emerging pollutants in marine environments and marine organisms .Chlorinated paraffins (CPs) are a class of widely used industrial chemicals, which have been commonly used as flame retardants, plasticizers, and other additives in plastics and their products. Among them, short-chain chlorinated paraffins (SCCPs) and medium-chain chlorinated paraffins (MCCPs) have received global attentions due to their persistence in the environment, bioaccumulation, and aquatic toxicity. China is the largest producer and user for CPs, and the distribution and ecological risks of SCCPs and MCCPs in marine environments are particularly worthy of attention. In this study, a total of 12 marine species were sampled from the North Yellow Sea of China, encompassing seven fish species and five benthic organisms. Stable nitrogen/carbon isotope analysis was adopted to determine their trophic level. Quantitative analysis of SCCPs and MCCPs was conducted using gas chromatography-electrostatic field orbitrap high resolution mass spectrometry (GC-Orbitrap-HRMS). This study revealed the presence of SCCPs and MCCPs in all specimens. The SCCP concentrations ranged from 29.2 to 2450.4 ng/g dry weight (dw) which was higher than MCCPs in the range of 12.1-1362.8 ng/g dw. The concentrations of SCCPs and MCCPs in the marine species were strongly correlated with lipid content (r²=0.61, p<0.05). The congener patterns of SCCPs were dominated by C₁₀-CPs and C₁₁-CPs, while MCCPs was dominated by C₁₄-CPs. The Cl_7-8 congeners predominated in the distribution of both SCCPs and MCCPs. The biomagnification factors (BMF) of SCCP and MCCP congeners decreased with an increase in their octanol-water partition coefficient (log Kow). SCCPs (BMF=0.23) and MCCPs (BMF=0.14) showed biological dilution effect between the predator Sebastes schlegelii and its prey Larimichthys polyactis. In addition, the potential exposure risk of SCCPs and MCCPs from fish consumption were assessed, with the maximum hazard quotient (HQ) values of 0.04 and 0.06, respectively. For both rural and urban residents, the levels of SCCPs and MCCPs ingested through consumption of these fish would not have a significant impact on human health.