Nonylphenol ethoxylate (NPE) is widely used as a component of detergents, paints, pesticides, and many other products. In the aquatic environment NPE breakdown to 4-nonylphenol (NP), which is more stable and persistent. NP is estrogenic in fish, avian, and mammals and is described as an environmental pollutant with endocrine disruptor characteristics. The genotoxicity of NP was evaluated through micronuclei assay and single cell gel electrophoresis (Comet assay) in peripheral erythrocytes of Oreochromis niloticus exposed in vivo. The study on reproductive development was also carried out in male and female gonads of O. niloticus. Lethal concentration (LC 50%) of 0.032 ml l -1 was previously determined. We ran assays with O. niloticus exposed to concentrations of 1.0, 10.0, and 16.0 ll l -1 of NP diluted in water. Our results showed that NP was not genotoxic. However, 3-day exposure to NP in concentrations of 1.0, 10.0, and 16.0 ll l -1 of water increased the frequency of reproductive stages in males and females. The histology of the reproductive tract of the treated fish was significantly altered in females treated with 16.0 ll l -1 of water when compared to controls. Analogous estrogenic effects were observed, such as accelerated maturation of oocytes and spermatogenesis. These results showed that the O. niloticus reproductive system is sensitive to NP estrogenicity.

This study evaluated the effects of [D-Leu(1)]Microcystin-LR variants, by the exposure of Hypophthalmichthys molitrix to Microcystis aeruginosa NPLJ4. Fish was placed in aquariums and exposed to 10(5) cells mL(-1). For 15 days, 05 individuals were removed every 05 days, and tissue samples of liver, skeletal muscle and intestinal tract were collected for histopathologic analyses. Following exposure, those surviving were placed in clean water for 15 days to evaluate their recovery. A control without toxins was maintained in the same conditions and exhibited normal histology and no tissue damage. In exposed fish, samples were characterized by serious damages that similarly affected the different organs, such as dissociation of cells, necrosis and haemorrhage. Samples showed signs of recovery but severe damages were still observed. The results should be valuable to analyze the potency of microcystin toxicity and to help in the diagnosis of fish deaths.

ABSTRACT. 17-α-methyltestosterone (MT) is a synthetic hormone used in fish hatcheries to induce male monosex. Snails hold promise as possible test models to assess chemicals acting on the endocrine system. Biomphalaria glabrata is an aquatic gastropod mollusk (Pulmonata, Planorbidae) that can be easily maintained in aquaria, predisposing the species for use in ecotoxicological testing. This study evaluated the reproductive effects of MT on B. glabrata by examining histological changes and its reproductive performance. Ten snails per group were exposed for 4 weeks to different concentrations of MT (0.01, 0.1, and 1.0 mg/L). The total number of laid eggs, egg mass per group, size of type V oocytes, and production of spermatozoids were determined. Reproduction of B. glabrata was affected by MT. At the lowest concentration (0.01 mg/L), MT caused a statistically significant increase in the number of egg mass per snail compared with controls unexposed to MT. Histopathology analyses showed an increase in the sperm production at the higher MT concentrations of 0.1 and 1.0 mg/L. Chromatographic analyses of water samples showed that MT concentrations rapidly declined within a 96-h period. These results highlight the importance of giving more support to regulatory authorities, since MT is not registered for use on fish hatcheries in many countries around the world. Wastewater from fish farms discharged into aquatic ecosystems should be monitored for MT residues, since its presence could compromise the reproduction of other native snail species.

ABSTRACT. The synthetic hormone, 17-α-methyltestosterone (MT), is used in fish hatcheries to induce male monosex. Androgenic effects on various fish species have been reported; however, few studies have assessed possible genotoxic effects, although there are concerns about such effects in target and non-target species. We evaluated genotoxic and gonadal effects of MT in adult tilapia (Oreochromis niloticus) and Astyanax bimaculatus (a common native non-target fish in Brazil). Fish were fed for 28 days with ration containing MT (60 mg/L), a normal dose used in fish farming. Evaluation of MT genotoxicity was carried out through micronucleus test, nuclear abnormality, and comet assay analyses on peripheral erythrocyte cells collected by cardiac puncture. There were no significant differences in micronucleus frequencies and DNA damage in both species; however, MT caused cytogenetic toxicity in the non-target species, A. bimaculatus, with significantly increased erythrocyte nuclear abnormalities. Histopathological analyses of the female gonads of O. niloticus revealed that MT significantly inhibited the development of mature oocytes, while in A. bimaculatus it provoked Methyltestosterone's genotoxic and gonadal effects significant inhibition of spermatozoa production. We concluded that discharge of fish-hatcheries water onto the surface of aquatic ecosystems should be avoided due to risks to reproduction of native species.

Residual insecticide activity of BHC vapors from various building materials in controlled humidity chambers in the laboratory were significantly different. Laboratory-reared, first instar nymphs of Dipetalogaster maximus were exposed to vapors of BHC which were being released from the treated surfaces of building materials taken from Mambaí, Goiás.

The pyrometallurgical process of mining for obtaining ferronickel involves a stage of calcinations. At this stage a residue is generated described as a calcination dust of fine black grains. Analysis of this material revealed a significant presence of Fe, around 53,000 ppm and Ni, around 14,000, beyond of other metals as Al, Mn, and Cr. Adults and larvae of Oreochromis niloticus were used to evaluate acute toxicity, cytotoxicity and genotoxicity, and histopathological effects. The data obtained show absence of toxicity in concentrations of 5, 10 and 50% but a considerable potential for bioaccumulation in the fish's body.

ABSTRACT. 17α-Methyltestosterone (MT) is widely used in fish hatcheries of many countries to produce male monosex populations. Its genotoxic risk to fish species is not well known and studies in other in vivo models are still inconclusive. MT was tested for genotoxicity in the fish species Oreochromis niloticus (tilapia), a target species, and Astyanax bimaculatus (lambari), a native non-target species. Genotoxicity was evaluated by the micronucleus test (MN), nuclear abnormalities (NA), and comet assay using peripheral erythrocytes of both species after a 96-h exposure to MT at concentrations of 0.01, 0.1, and 1.0 mg/L in the water. At the lowest exposure level of 0.01 These effects were not observed in the comet assay. Chromatographic analysis of water samples collected from aquariums at the beginning and end of each experiment showed that MT was consumed during the 96-h exposure. At the highest level of exposure (1.0 mg/L), 81.69% of the hormone was consumed during the exposure period. The chromatogram showed that at the lowest concentration level of 0.01 mg/L, 99.56% MT was consumed by the end of the exposure period. Thus, exposure to MT did not cause genotoxicity in either fish species.

Mining to obtain ferronickel by the pyrometallurgical process involves a calcination stage that generates a highly metallic solid dust. This study evaluated the bioavailability of metals from calcination dust after being ingested by Oreochromis niloticus. Chemical analysis was performed on the whole body and histological analysis was performed on the gills and gastrointestinal tract of fish to evaluate potential bioaccumulation. After 96 h of exposure to the dust, gill tissue contained a small amount of particulate matter, while the gastrointestinal tract was filled with the material, generating high values of metals in the fish whole body chemical analysis. However, after 15 and 30 days in clean water, both the gills and gastrointestinal tract were nearly devoid of particles and metal concentrations in the fish whole body had largely returned to baseline levels.