Assessing the recency of organochlorine pesticides (OCPs) inputs and their related risks in the soils of a heavily anthropized area

AbstractThe Sarno River Basin (SRB) is among the most polluted rivers in Europe. The contamination derives from industrial activities, intensive agriculture and dense urbanization. To assess the geochemical–environmental conditions of the SRB, OCP concentrations from 42 topsoil samples falling within the study area were evaluated to investigate their distribution patterns and infer pollution sources.The concentration of Ʃ24OCPs ranges from 0.15 to 345 µg/kg. Dichlorodiphenyltrichloroethane (DDT) and its isomers and metabolites represent the most abundant compounds (0.021–339 µg/kg), with p,p′–dichlorodiphenyldichloroethylene (p,p′–DDE) showing the highest concentrations (up to 230 µg/kg).Isomeric ratios were calculated to determine whether the detected concentrations are consistent with relatively fresh applications or historical residues of these substances. An OCP Recency Index (ORI) was developed by integrating multiple diagnostic ratios across OCP groups to provide a spatially consistent indicator of the relative contribution of recent versus legacy inputs. Results showed that, although the use of most OCPs is currently banned, more recent applications of pesticide mixtures presumably contribute to high soil concentrations found in some parts of the study area.In addition, a human health risk assessment was conducted, focusing on adult workers. The analysis revealed that carcinogenic risks associated with DDT isomers are widespread, in some cases well above the levels considered acceptable according to USEPA guidelines, indicating a significant potential health concern for individuals engaged in agricultural activities. In contrast, risks associated with other OCP groups were limited to a few isolated samples or were absent.