Determination of the Lethal Concentration 50% (LC<sub>50</sub>) of Hexavalent Chromium in Nile Tilapia (Oreochromis niloticus)

Abstract

The contamination of heavy metals in water is a worldwide issue which is increasing day by day due to the different types of anthropogenic activities. These heavy metals pose a serious health risk on aquatic organisms. One such heavy metal is chromium. The present study is about to determine 24h, 48h, 72h and 96 hours LC₅₀ value of hexavalent chromium for the Nile Tilapia, Oreochromis niloticus. In the present study, 24h, 48h, 72h and 96h of exposure of Nile Tilapia (Oreochromis niloticus) to potassium dichromate (K₂Cr₂O₇) was able to measure the hexavalent chromium lethal concentration 50 (LC₅₀) in Nile Tilapia (Oreochromis niloticus). A kind of computational and graphical technique can be applied to obtain an LC₅₀ (median lethal concentration) from the response of concentration-mortality data produced by an acute mortality experiment. No process should be applied that does not evaluate both LC₅₀ and its 95% confidence limits. The data were statistically analyzed by the application of SPSS software based on Finney's Probit Analysis Method and a 24h, 48h, 72h, and 96 h LC₅₀ values for Oreochromis niloticus were found to be 121.06mg/l, 108.30mg/l, 99.31mg/l, and 93.49mg/l respectively. With the increase of the concentration of metal, the response of the fish mortality increased gradually. The mortality of the fish is directly proportional to the concentration of the exposed metals. The results indicate that hexavalent chromium revealed acute toxicity to fish when exposed for 96 hours and this could release the fact that exposure to hexavalent chromium may outcome in deleterious toxic effects to fish that influences the health of the aquatic environment.