Occurrence, sources, and risks of short-, medium-, and long-chain chlorinated paraffins in sediments from an e-waste recycling area in China

) were moderate globally and relative to other flame retardants in the same river. CP levels showed a clear spatial pattern: lowest at headwaters, highest around Guiyu, and declining downstream, identifying e-waste as their primary source. Domestic wastewater and sedimentary organic carbon content also significantly influenced the CP distribution. Source analysis revealed that imported e-waste and China's CP-52 products contributed over 50% of the river's CP burden, followed by SCCP-containing products/waste (13-29%) and domestic CP-70 applications (8-33%). Hazard quotient (HQ) results indicated acceptable ecological risk (HQ < 1) at all sites except two in Guiyu. SCCPs showed the highest HQs despite intermediate concentrations; MCCPs contributed the most mass but intermediate HQs; and LCCPs exhibited the lowest concentrations and risks. These findings provide the first comprehensive pollution and risk assessment of all CP classes along a sediment transect encompassing an e-waste recycling zone, providing critical insights into emerging LCCP contamination.