Occurrence and human health implications of organochlorine pesticides in Nile tilapia from Al Massira Reservoir (Morocco) across consumer groups

Organochlorine pesticides (OCPs) are persistent environmental contaminants that continue to occur in aquatic ecosystems due to their high stability and bioaccumulative properties.This study quantified the OCP residues in the muscle tissue of Nile tilapia (Oreochromis niloticus) collected from the Al Massira Reservoir (Morocco) and evaluated the potential human health risks associated with fish consumption.A total of 120 specimens collected between July 2022 and June 2023 were analyzed for eight OCPs (α-HCH, β-HCH, γ-HCH, aldrin, dieldrin, p,p′-DDD, p,p′-DDE, and p,p′-DDT) using gas chromatography-mass spectrometry (GC-MS).Human exposure was assessed through estimated daily intake (EDI) and hazard ratio (HR).All target compounds were detected, with concentrations ranging from below the detection limit to 8.445 ng g⁻¹ wet weight.Dieldrin and p,p′-DDT were the predominant residues, whereas p,p′-DDD occurred at the lowest concentrations.No significant temporal variation was observed during the sampling period (ANOVA, p > 0.05).OCP concentrations showed no significant relationship with fish total length, whereas dieldrin concentration exhibited a significant positive relationship with fish body weight (R² = 0.238; p = 0.016).All measured residue concentrations remained below the international maximum residue limits, and the estimated daily intake as well as hazard ratio values for all consumer groups were below the recommended safety thresholds, indicating a low health risk associated with Nile tilapia consumption.This study provides one of the first comprehensive assessments of the OCP contamination in Nile tilapia from the Al Massira Reservoir, one of Morocco's largest freshwater reservoirs.The findings establish valuable baseline data for future environmental monitoring, ecological risk assessment, and food safety management of Moroccan freshwater ecosystems.