Environmental emission, transport, and exposure risk of polychlorobutadienes and chlorinated benzenes from light industries

Limited research has been conducted on source and transport of polychlorobutadienes (polyCBDs) and chlorinated benzenes (CBs) through various media, some of whose congeners have been listed as persistent organic pollutants in the Stockholm Convention and pose serious risks to human health. This study analyzed 9 polyCBDs (Cl: 4-6) and 11 CBs (Cl: 2-6) in 11 types of environmental media from a typical light industry area in East China. Dyeing, paper, and waste incineration were identified as important sources, where the concentrations of target pollutants in dyeing (∑polyCBDs: 22.8 ng L^-1; ∑CBs: 2203 ng L^-1) and paper wastewater (17.7 ng L^-1; 131 ng L^-1) were 2-3 orders higher than those in river (0.09 ng L^-1; 1.36 ng L^-1). Hexachlorobutadiene (HCBD) was widely detected in solid media with the average concentrations in the order of road dust > land leaves > road surface soil > water hyacinth > river sediment > subsoil > river-bank soil. The fugacity model showed that the intermedia transfer fluxes of HCBD and CBs between water-to-sediment were higher than those between sediment-to-water and soil-to-water in aquatic environment. Besides, polyCBDs and CBs showed a long-term pattern of infiltration from shallow to deep layers in subsoil. The non-carcinogenic and carcinogenic risk of polyCBDs and CBs in the investigated area were minimal. Nevertheless, ingestion as the major human exposure route to polyCBDs and CBs needs more attention. This comprehensive study enhanced the acknowledge of polyCBDs and CBs contamination in light industries, providing theoretical foundation for scientific prevention of these emerging pollutants.