Occurrence and Health Risk Assessment of Organochlorine Residues in Cowpea Grains Marketed in Abuja, Nigeria

The main objective of this study was to determine the prevalence and concentration level of organochlorine residue in marketed cowpea grains in the Federal Capital Territory (FCT) -Abuja, Nigeria, and assessed the health risk to the consumers. The randomly collected 140 samples were bulked into 28 laboratory samples for analysis. The samples were extracted and cleanup using Quick Easy Cheap Efficient Rugged and Safe (QuEChERS) methods. Twenty organochlorine compounds comprising benzene hexachloride (BHC), heptachlor, aldrin, chlordane, endosulfan, dichlorodiphenyltrichloroethane, methoxychlor, heptachlor, endosulfan, and their metabolites were quantified using gas chromatography-mass spectrophotometer (GC-MS). The recovery percentage of OCs residues were in the range of 90.1 to 93.7% and the limit of detection ranged between 0.00003 and 0.00020 mg kg-1. The prevalence of the contaminated cowpeas samples with p,p’-dichlorodiphenyltrichloethane (DDT), endosulfan sulphate, and endrin ketone was 89.29%. Aldrin, dieldrin pp’- p,p’-dichlorodiphenyldichloethylene (DDE), alpha BHC, Delta-BHC had an incidence of 75.00, 32.14 and 57.14 % respectively. None of the OC residues were detected in the cowpea grains obtained from Utako market (UW). Mean residual concentration of the OCs insecticides in the samples ranged between 0.000068 to 0.006633 mg kg-1. The mean concentration level of heptachlor epoxide (0.0550 mg kg-1), methoxychlor (0.0147 mg kg-1), and endrin ketone (0.0663 mg kg-1) were above the EU limits of 0.020, 0.010 and 0.050 mg kg-1 respectively.and the concentration level of all the other 17 compounds in all the samples were below the EU maximum limit. Human risk assessment indicated that all the detected OCs residues were within Acceptable Daily Intake (ADI). The mean value for Hazard index (HI) revealed that endrin ketone (27.2616) was > 1 while the combined health hazard of OCs was < 100 and consumption of the samples might poses health risk due to presence of the banned OCs. This study suggests that cowpea grains sold in the study area pose a potential health risk to the consumers.