Concentration evaluation and risk assessment of pesticide residues in selected vegetables sold in major markets of Port Harcourt South-South Nigeria

Abstract

Abstract Concentration levels and health risk assessment of residues of organochlorine and organophosphate pesticides in four commonly vegetables (Cucumber, carrot, cabbage, and eggplant) collected from major markets of Port Harcourt city, South-south Nigeria were assessed. The collected samples were analysed using QuEChERS (quick, easy, cheap, effective, rugged, and safe) extraction method by gas chromatography coupled with Electron Capture Detector (ECD). Pesticide concentrations were compared with UK/EU maximum residual limits (MRLs). Health risk estimates were analysed using estimated daily intake (EDI), hazard quotient (HQ), and hazard ratio (HR) for children (16.7 kg) and adults (60 kg) weight groups. The results of this study showed that 80% of the vegetable samples contained detectable pesticide residues, of which 70% had residues that exceeded MRLs while 20% had residues below detectable levels. The highest concentrations of HCH residues are present in cabbage with a concentration of 0.25 ± 0.15 mg/kg for α-HCH while the least are present in eggplant with concentration of 0.038 ± 0.025 mg/kg in lindane. Pirimophos-methyl was detected in cucumber at 0.017 mg/kg while parathion and isofenfos was detected only in eggplants at concentration of 0.042 mg/kg and 0.022 mg/kg respectively. Concentrations of parathion, chlorpyrifos, and pirimophos-methyl residues were lower than MRLs in all the detected vegetable samples analysed. Non-carcinogenic health risk estimates for the children consumer groups showed that mevinfos, p, pʹ DDD, aldrin, and heptachlor epoxide detected in eggplant, carrot, and cabbage had HQ > 1. While for adults, only p, pʹ DDD and heptachlor epoxide revealed non-carcinogenic effect in cabbage. Risk was highest for child consumers. However, most of the pesticide residues were less than 1 for the HQs value which is indicative of insignificant health risk. Human risk estimations for the carcinogenic health effect for the studied vegetables showed that lindane and delta HCH could pose carcinogenic health risks to adult, while aldrin, dieldrin, heptachlor, α HCH, β HCH, delta HCH, and heptachlor epoxide could pose carcinogenic health risks to children. The HRI values in some of the detected residues indicate that the cancer benchmark concentrations exceeded the EDI for the respective organochlorine pesticide in the vegetable samples, thus raising serious concerns of possible carcinogenicity. Non carcinogenic and carcinogenic risk assessment of organochlorine pesticide residues in the studied vegetable indicates health threat. Hence, strict monitoring and control of pesticide residues in agricultural products is being suggested, to protect consumers, especially the children who are vulnerable to the adverse effects of pesticides.