Risk assessment and influence factors of organochlorine pesticides (OCPs) in agricultural soils of the hill region: A case study from Ningde, southeast China

• The OCP residues in agricultural soil from Ningde were investigated and assessed for the first time.
• HCHs, DDTs and Endosulfans were the most dominant contaminant among the 20 OCPs.
• The OCP residues especially DDTs were remarkably influenced by land-use type.
• The residue levels of OCPs in agricultural soils were slightly controlled by TOC.
• The agricultural soils polluted by OCPs may pose a high potential carcinogenic risk for exposed populations.

Surface soil samples from farmlands in Ningde were analyzed for 20 organochlorine pesticides (OCPs) with the aim of elucidating contamination profiles, distribution characteristics, influencing factors and carcinogenic risks of these compounds in this hilly region. The total concentrations of OCPs ranged from 3.66 to 658.42 ng/g, with a mean of 78.83 ng/g. HCHs, DDTs and Endosulfans were the predominant contaminants in agricultural soils. The residual levels of OCPs on vegetable farmlands were significantly higher than those of corresponding counterparts on paddy farmlands, mainly attributed to variations in pesticide application and OCP degradation in the soils. Potential source analysis traced the occurrence of high residual levels of DDTs and HCHs to historical applications. Spearman correlation analysis pointed to TOC as a significant variable controlling OCP distribution, and artificial influences possibly contributed to the fate of OCPs in the soils. The OCP contamination levels in the agricultural soils based on national standards are generally considered safe for crop production, but they however, pose significant carcinogenic risks to exposed populations based on the calculated results of the incremental lifetime cancer risk (ILCR) parameters.