The Distribution Characteristics and Risk Assessments of Organochlorine Pesticides in the Sediments of Sanshan Lake, China

Situated in the middle reaches of the Yangtze River, Sanshan Lake represents a typical rural-urban junction lake. In May 2019, sediment core samples were gathered from five distinct sites within the lake to assess contamination levels and potential health hazards stemming from organochlorine pesticides (OCPs). The OCPs scrutinized included p,p'-DDE, alpha-HCH, gamma-HCH, beta-HCH, and delta-HCH, with concentrations of n-ary sumation DDTs and n-ary sumation HCHs ranging from 0.03 to 1.49 mg/kg and from 0.03 to 1.42 mg/kg, respectively. Average DDT and HCH residues stood at 0.04 +/- 0.03 and 0.51 +/- 0.41 mg/kg, respectively. This study unveiled substantial OCP contamination in Sanshan Lake, notably with remarkably elevated HCH residue levels compared to other analyzed compounds. The predominant OCP detected was beta-HCH, prevalent across all samples. Moreover, the average HCH residue concentrations were an order of magnitude higher than those found in soils of the United States and Italy. At some sampling points, DDT residue levels surpassed both the ecological screening benchmark for soil DDT established by the U.S. Environmental Protection Agency (0.0025 mg/kg) and China's primary standard as per soil environmental quality regulations (GB15618-2008, 0.05 mg/kg). Source analysis indicated that historical agricultural practices primarily contributed to DDT contamination, while technical blends accounted for HCH pollution. Carcinogenic risk assessments conducted on HCH exposure through ingestion, inhalation, and dermal contact revealed higher non-carcinogenic risks for children, with alpha-HCH posing the most significant carcinogenic risk among the various homologues studied. Conversely, the associated carcinogenic and non-carcinogenic risks linked with DDT residue exposure were minimal or negligible.