Cytotoxicity of Waters of a Tropical Lagoon and Contamination of Tilapia Guineensis by Lead, Zinc, Copper and Cadmium: Case of Agbokou and Porto-Novo bridge sites (South of Benin)

Abstract

The demographic explosion and the industrial revolution had consequences as the discharge of domestic and industrial waste in the lakes and lagoons which polluted them, involving serious environmental problems and of public health. The objective of this study is to know the level of total toxicity of two sites of the Porto-Novo lagoon and to determine the content of lead, zinc, copper and cadmium in the fish Tilapia guineensis. The aim of this study is to evaluate the toxicity of water of two sites by the test of cytotoxicity on the inhibition of the growth of the roots of onions and to determine the content of the Metal Elements Traces (MET) such as lead, zinc, copper and cadmium in the flesh, the head, the liver and the edges of the fish Tilapia guineensis fished in the Porto-Novo lagoon by the spectrophotometric method of atomic absorption. The test of cytotoxicity showed that waters of sampling of two sites do not have global toxicity because the average lengths of the roots of onions exposed to various concentrations of water of the two sites does not depend on those. Thus the inhibition of the growth of the roots of onions does not depend of the concentrations on water on the two sites. But the malformations observed such as the deformed or turned over roots constitute precursory signs of a genotoxicity. The mineralisation of various parts of the fishes Tilapia guineensis was made by protocol HACH and the content of lead, zinc, copper and cadmium was determined using the spectrophotometer of atomic absorption. The analyses revealed that the Metal Elements Traces such as lead, zinc, copper and cadmium are concentrated in the various parts of the fish tilapia guineensis to the variables degrees.