Human risk Assessment of heavy metals in fishes from Dadin-Kowa Dam, Yamaltu, Gombe State, Nigeria

This study was designed to detect occurrence and levels of concentration of Arsenic (As), Lead (Pb) and Cadmium (Cd), and their relationship with species, age and sex of fish as well as health risk to man. A total of 201 fishes were sampled using systematic random sampling from Dadin-Kowa Dam, Yamaltu Deba Local Government Area of Gombe State, Nigeria. Heavy metals (HMs) concentrations were determined by Atomic Absorption Spectrophotometer. HMs frequency of occurrence observed was 37% in the muscle of the fish samples analyzed with As recording the highest 36%, followed by Pb 1% and then Cd 0%. Likewise, the percentage proportion for As among all the positive samples was 97% and that of Pb was 3%. The mean concentration for As (0.0216 ± 0.041) and Pb (0.0002 ± 0.002) were significantly (p < 0.0001) lower than their respective Maximum Allowable Limits (MAL) values of 1 mg/kg for As and 0.5 mg/kg for Pb. Unlike sex, there was a significant association (p= 0.002) between species and As contamination with L. niloticus recording the highest frequency of occurrence (57%), followed by 54%, 29% and 25% for O. niloticus, C. gariepinus and S. membranaceus respectively. Young fishes had significantly (p < 0.05) higher levels (0.0317 ± 0.052) and frequency of occurrence 35 (49%) compared to adult (0.0160 ± 0.033) and 37 (29%) respectively. The non-carcinogenic and carcinogenic risk values of As and Pb were estimated to be less than one; thus, fish from the dam is safe and harmless for human consumption.