Freshwater environment risk assessment and derivation of human health ambient water quality criteria for SCCPs in China

Short-chain chlorinated paraffins (SCCPs, CxH2x+2-yCly, where x = 10 to 13 and y = 3 to x) are a complex family of emerging contaminants that have been identified as persistent, bioaccumulative and toxic (PBT) substances. Because of their persistence, high toxicity, bioaccumulation and long-distance mobility, SCCPs were added to the list of controlled POPs in the Stockholm Convention in 2017. China is the largest producer and user of SCCPs all over the world, thus SCCPs have been widely distributed in the freshwater environment. But the ecological risk and human health risk of SCCPs in China were still less evaluated. This study collected and screened the exposure data of SCCPs in freshwater environment in China, and then evaluated the freshwater and sediments ecological risk of SCCPs by risk quotient (RQ) method and the human health risk by margin of exposure (MOE) method. Our results showed that the pollution of SCCPs in the freshwater environment in China was not optimistic. The ecological risks and human health risks had occurred, and even there were high ecological risks occurred in some regions in China. Besides, because of the absence of the concentration threshold of SCCPs to protect human health in freshwater at present, we derived the human health ambient water quality criteria (AWQC) values of SCCPs based on exposure data and bioaccumulation factor (BAF) in China. The human health AWQC values of SCCPs ranged from 14.99 ng L-1 to 154.54 ng L-1 in different regions in China, and the national human health AWQC value was determined as 24.08 ng L-1. This study will provide the scientific references for the management and control of SCCPs in China, especially for the formulation of standard of water environmental quality for SCCPs.