Biota occurrence, accumulation, disposition and toxic effect of chlorinated paraffins

Chlorinated paraffins (CPs) are high-production-volume synthetic chlorinated n-alkanes that categorized as short- (SCCPs), medium- (MCCPs) and long- (LCCPs) chain CPs based on carbon chain length. CPs have received growing attention due to their wide usage, ubiquitous detection, persistence and potential toxicity. The present study reviewed the current production and emission status, biota occurrence, accumulation, toxicokinetic and toxicity of CPs. Commercial CPs are highly complex mixtures, and their physicochemical properties vary across a wide range. High detection rates and concentrations of CPs in aquatic non-vertebrates, fish and birds were reported. SCCPs and MCCPs in birds and other organisms are relatively higher in Asia. Bioaccumulation and biomagnification of SCCPs and MCCPs occurred in both aquatic and terrestrial food webs. Early studies indicated low acute toxicity, while recent evidence suggests CPs exposure elicits potential risk on liver, kidney, endocrine system, immune system and embryonic development. Significant data gaps persist in accurate production reporting, predicting their environmental emissions and distribution because of their structural complexity. As CPs are proved to persistent and bioaccumulative, the impacts of long-lasting exposure for both ecosystem and human health required continuous monitoring and evaluation.