The concentrations of heavy metals and the incidence of micronucleated erythrocytes and liver EROD activity in two edible fish from the Paraiba do Sul river basin in Brazil

The Paraiba do Sul river (PSR) basin crosses one of the most populated and industrialized regions of Brazil and receives effluent from the metallurgic, paper mill and agricultural industries. PSR water has multiple uses, including being a supply of potable water and riverine populations which consume some species of its fish. In the present study, we investigated the responses of two biomarkers of aquatic pollution, EROD activity in the liver and micronuclei frequency in peripheral blood, as well as the concentrations of seven heavy metals in the muscle tissue of two species of fish native to the PSR: Geophagus brasiliensis and Hypostomus sp. Sampling was performed in both the wet and dry seasons of 2003, with a total of 339 fish collected from 16 sites along the PSR basin. Fish collected at Levy Gasparian, Barra Mansa and Tres Rios both had higher EROD activity and micronuclei frequency. The results also suggested a moderate induction of EROD activity in fish collected from S.L. Paraitinga and Sapucaia. Micronuclei frequency was elevated in fish from S.J. Campos, Alem Paraiba, Campos and S.J. Barra. In all cases, heavy metal concentrations did not exceed the maximum considered safe for fish meat consumption.