Contamination of Pesticide residues and Human Health Risk Assessment of the Selected Agricultural Soils in Oyo State, Nigeria

<title>Abstract</title> <p>This study investigated pesticide residues contamination in agricultural soils from Ibarapa and Oke - Ogun regions of Oyo state, Nigeria. Soil samples were collected from four farms, located in Ibarapa (Araromi and Jakode) and Oke - Ogun (Itasa and Oke - Ola). Ten sub-samples collected within a 10–20 m radius at a depth of 0–20 cm and bulked in each location and analysed for pesticide residues (organochlorine, and pyrethroid) using GC–MS. The data were compared with World Health Organisation/Food and Agriculture Organisation (WHO/FAO) Limits and subjected to statistical analyses [hierarchical Clustering (HC), Discriminant Analysis (DA), Pincipal Conponent Analysis (PCA)], Toxicity Assessment (spatial mapping, chemometric profiling), and Health Risk assessment [Risk Quotient (RQ) and probabilistic risk (Monte Carlo simulation) modelling]. Multiple residues were detected in all sites, with Pyrethroid (heptachlor, heptachlor epoxide, aldrin, dieldrin, endosulfan I/II, endosulfan sulfate), and Organochlorine (p,p′-DDT/DDD, chlorothalonil, lambda-cyhalothrin, and cypermethrin isomers). Concentrations were highest in Jakode and several analytes exceeded WHO/FAO residue limits in all locations. PCA, HC, and DA separated a legacy organochlorine domain from a pyrethroid-associated domain. Co-occurrence network analysis demonstrated that the residue mixture was not random, but organized into tightly linked organochlorine and pyrethroid clusters. Health-risk screening showed that RQs for heptachlor epoxide and dieldrin (critical), aldrin and endosulfan (very high), and other compounds (high). Monte Carlo simulation showed &gt; 90% probability that Health Quotient exceeded unity under realistic exposure assumptions. However, the results show that the study areas are affected by both historical pesticide persistence and current agricultural inputs.</p>