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The sublethal effects of water-soluble fraction of gasoline (WSFG, 1.5 % v/v) were evaluated in the freshwater fish, Astynax altiparanae, after acute exposure (96 h) under a semi-static system. In addition, the recovery process was assessed in the fish following contaminant depuration. Recovery treatments were carried out with gradual depuration (GD), consisting of 7 days in the WSFG, followed by 8 days in clean water; and treatments with total depuration in clean water for 15 (DEP 15) and 30 days (DEP 30). The effects were evaluated through the piscine micronucleus test and by differential counting of organic defense cells. Acute exposure increased the frequency of neutrophils. In the GD treatment, the thrombocyte count and erythrocytic nuclear abnormalities (ENA) increased. In the DEP 15 treatment, there was a reduction of ENA; and following 30 days of depuration (i.e., DEP 30), the number of lymphocytes increased and the thrombocyte count remained high. These results indicate a long-term response to a condition of stress from WSFG.

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Metallic nanoparticles are one of the most produced and used engineered nanomaterial and their wide applications lead to environmental contamination. The aquatic environment is the major recipient of wastes containing nanoparticles and other co-occuring contaminants. We aimed to evaluate genotoxic and biochemical effects of acute exposure to nano-TiO 2 in the fish Hoplias intermedius and the interaction to metals. Besides assessing the nanoparticles' physical-chemical properties we performed an acute exposure with 0.1; 1; 10 µg g-1 nano-TiO 2 , alone and with lead (21 µgg-1) and aluminium (50 µgg-1). A set of biomarkers were evaluated in the liver such as genotoxicity by comet assay and biochemical biomarkers (SOD, CAT, GPx, GSH, EROD, GST). Most of the biomarkers were altered by the metals, and the nanoparticles caused decrease in SOD (0.1 and 1µg g-1), GSH (1µg g-1), and GST (0.1 µg g-1). In co-exposure, some metal effects were attenuated. There was an increase in EROD activity for most co-exposure groups. Nano-TiO 2 was not genotoxic in the experimental conditions. We did not observe any increase in DNA breaks in co-exposure, although, nanoparticles changed the response of some biochemical biomarkers.