HEAVY METALS IN THE MYONEMATIC, HEPATIC AND RENAL TISSUES OF THE AFRICAN CAT FISH (Clarias gariepinus) FROM OGBA RIVER, BENIN CITY, NIGERIA.

Abstract

The concentrations of heavy metals (Pb, Cd, Zn, Cu, Cr and As) in the myonematic, hepatic and renal tissues of the African catfish (Clarias gariepinus) from Ogba river, Benin City, Nigeria, were determined using a Unicam 929 series atomic absorption spectrophotometer. The concentrations of the aforementioned metals were also determined in water. The mean concentration of Pb ranged from 0.19mg/kg (muscle) to 0.39mg/kg (liver) while the mean concentration of Cd ranged from 0.03mg/kg (muscle) to 0.09mg/kg (liver). The mean concentration of Zn ranged from 0.09mg/kg( muscle) to 0.33mg/kg (liver) while the mean concentration of Cu ranged from 0.23mg/kg (muscle) to 0.76mg/kg(liver). The mean concentration of Cr ranged from 0.19mg/kg (muscle) to 0.41mg/kg (liver) while the mean concentration of As ranged from 0.36mg/kg (kidney) to 0.54mg/kg (muscle). The mean concentrations of the heavy metals in water were Pb(0.09mg/l), Cd(0.04mg/l), Zn(0.01mg/l), Cu(0.53mg/l), Cr(0.38mg/l) and As(0.59mg/l). With the exception of Cu, the mean concentrations of the heavy metals in water were generally above the World Health Organization (WHO) maximum allowable limit for the respective metals in drinking water implying that water from the river is unfit for human consumption owing to heavy metal contamination. The mean concentrations of Cr and As exceeded the WHO maximum allowable limits for fish food. The direct implication of this finding is that people who consume fish from the river are liable to potential health hazards resulting from Cr and As contamination.