Risk assessment of pesticide residues in fish samples from Nwaniba River, Akwa Ibom state, Nigeria

Abstract

This study was conducted to determine the levels of contamination of organochlorine pesticide residues in fish from Nwaniba River in Uruan Local  Government Area of Akwa Ibom State. A total of 18 samples of different species of fish were obtained at two stations within Nwaniba River. The analysis  of residual pesticides was carried out using Gas Chromatography coupled with electron capture detector (GC-ECD). The obtained results revealed the  predominance of Dieldrin in the different samples of fish analysed from Ufak Effiong in the southern District (station 1) and Akani Obio in Uruan Central  District (station 2) of Uruan. Pesticide levels were found to be significantly higher than the World Health Organization/Food and Agricultural Association  (WHO/FAO) Maximum Residue Limits (MRL). The levels of organochlorine pesticides (OCPs) ranged from Below detection limit (BDL) to 8.53 × 10^-2 ng/µL  for fish samples. Carcinogenic risk values for gamma - BHC, delta - BHC, Dieldrin, Endosulfan I and Heptachlor epoxide in the fish samples were found to  be less than 1.0 × 10^-5 , thus posing no potentially serious cancer risk to consumers. The values of cancer risk obtained in this study were lower (6.448 × 10^-11 and 7.208 × 10^-11) than the established maximum limit. This study also revealed that hazard index (HI) of OCPs in fish were higher in children than  adults except silver catfish in adults from Akani Obio (0.78807), showing no potential risk since HI is less than or equal to 1. The hazard index of OCPs in  other fish species (Nile tilapia and Upside-down catfish) exceeded the threshold value of 1, which is evidence that daily exposure could pose potential  ecological and public Health concern.