Occurrence and remediation of chlorinated paraffins in global environmental matrices: Levels, trends, and future prospects

Abstract

Chlorinated paraffins (CPs), especially short-chain (SCCPs) and medium-chain (MCCPs) homologues, have become a global concern due to their highly toxic and persistent. However, there remains a limited and fragmented understanding of their distribution and hotspots across diverse environmental matrices worldwide, and research on effective control measures is even more deficient. This study investigated the global occurrence of CPs in multiple environmental matrices and reviewed existing degradation technologies. Emissions from industrial activities, product usage and environmental matrices exchanges have led to widespread CPs contamination mainly encompassing SCCPs and MCCPs, with average concentrations of 10⁻³–10³ ng/m³ in atmosphere, 10–10³ ng/L in water and 1–10⁵ ng/g dw in sediment, as well as 1–10⁶ ng/g dw in soil. In contrast, data on long-chain CPs (LCCPs) remain extremely limited. The available long-term atmospheric monitoring demonstrated both the effectiveness of regulatory controls and the delayed environmental response due to long-range atmospheric transport. The environmental migration of CPs is strongly influenced by carbon chain length and degree of chlorination. Current degradation technologies primarily focus on pyrolysis, photolysis, photocatalysis, microbial degradation, and phytoremediation. Mechanisms and efficiency analyses revealed that major challenges include by-products and the limited scalability of technologies beyond laboratory settings. By systematically linking contaminations profiles to suitable treatment options, we proposed a targeted CPs pollution remediation strategy. These insights aim to advance global CPs government and support the implementation of the Stockholm Convention.