RESUMO
Oil refinery effluents contain many chemicals at variable concentrations. Therefore, it is difficult to predict potential effects on the environment. The Atibaia River (SP, Brazil), which serves as a source of water supply for many municipalities, receives the effluents of one of the biggest oil refinery of this country. The aim of this study was to identify the (eco)toxicity of fresh water sediments under the influence of this oil refinery through neutral red (cytotoxicity) and ethoxyresorufin-O-deethylase (EROD) assays (AhR-mediated toxicity) in RTL-W1 cells (derived from fish liver). Once the refinery captures the waters of Jaguarí River for the development of its activities and discharges its effluents after treatment into the Atibaia River, which then flows into Piracicaba River, sediments from both river systems were also investigated. The samples showed a high cytotoxic potential, even when compared to well-known pollution sites. However, the cytotoxicity of samples collected downstream the effluent was not higher than that of sediments collected upstream, which suggested that the refinery discharges are not the main source of pollution in those areas. No EROD activity could be recorded, which could be confirmed by chemical analyses of polycyclic aromatic hydrocarbons (PAHs) that revealed a high concentration of phenanthrene, anthracene, fluoranthene, and pyrene, which are not EROD inducers in RTL-W1 cells. In contrast, high concentrations of PAHs were found upstream the refinery effluent, corroborating cytotoxicity results from the neutral red assay. A decrease of PAHs was recorded from upstream to downstream the refinery effluent, probably due to dilution of compounds following water discharges. On the other hand, these discharges apparently contribute specifically to the amount of anthracene in the river, since an increase of anthracene concentrations could be recorded downstream the effluent. Since the extrapolation of results from acute toxicity to specific toxic effects with different modes of action is a complex task, complementary bioassays covering additional specific effects should be applied in future studies for better understanding of the overall ecotoxicity of those environments.
Assuntos
Monitoramento Ambiental/estatística & dados numéricos , Peixes/metabolismo , Sedimentos Geológicos/química , Hidrocarbonetos Policíclicos Aromáticos/toxicidade , Rios , Poluentes Químicos da Água/toxicidade , Animais , Brasil , Linhagem Celular , Citocromo P-450 CYP1A1 , Monitoramento Ambiental/métodos , Fígado/metabolismo , Vermelho Neutro , Hidrocarbonetos Policíclicos Aromáticos/análise , Testes de Toxicidade , Poluentes Químicos da Água/análiseRESUMO
The Tietê River and its tributary Pinheiros River receive a highly complex organic and inorganic pollutants load from sanitary sewage and industrial sources, as well as agricultural and agroindustrial activities. The aim of the present study was to evaluate the embryotoxic and teratogenic effects of sediments from selected locations in the Tietê River Basin by means of the sediment contact embryo toxicity assay with Danio rerio, in order to provide a comprehensive and realistic insight into the bioavailable hazard potential of these sediment samples. Lethal and sub-lethal effects were recorded, and high embryo toxicity could be found in the samples not only in the vicinity of the megacity São Paulo (Billings reservoir and Pinheiros River samples), but also downstream (in the reservoirs Barra Bonita, Promissão and Três Irmãos). Results confirm that most toxicity is due to the discharges of the metropolitan area of São Paulo. However, they also indicate additional sources of pollutants along the river course, probably from industrial, agricultural and agroindustrial residues, which contribute to the degradation of each area. The sediment contact fish embryo test showed to be powerful tool to detect embryo toxicity in sediments, not only by being a sensitive method, but also for taking into account bioavailability. This test provides an ecological highly realistic and relevant exposure scenario, and should therefore be added in ecotoxicological sediment quality assessments.
Assuntos
Embrião não Mamífero/efeitos dos fármacos , Rios/química , Testes de Toxicidade/métodos , Poluentes Químicos da Água/toxicidade , Peixe-Zebra/embriologia , Animais , Brasil , Ecotoxicologia/métodos , Monitoramento Ambiental/métodos , Sedimentos Geológicos/química , Teratogênicos/toxicidadeRESUMO
Acute cytotoxicity (neutral red assay), AhR-mediated toxicity (CYP P450 1A induction potential-EROD assay) and concentrations of PAHs were recorded in RTL-W1 cells to assess the ecotoxicological potential of sediments from reservoirs along the Tietê River and the Pinheiros River (Brazil). Almost all sediments tested induced cytotoxicity and stimulated cytochrome P450-associated EROD activity. Toxicity increases from Tietê River spring to São Paulo city region and decreases towards downstream. A closer analysis of chemical measurements of PAHs and results from bioassay revealed that the PAHs analyzed could not explain more than 7% of the EROD-inducing potencies. Results confirm that most of the toxicity is due to the discharges of the metropolitan area of São Paulo. Moreover, they indicate additional sources of pollutants along the river course, which contribute to the degradation of each reservoir.
Assuntos
Dioxinas/toxicidade , Monitoramento Ambiental , Sedimentos Geológicos/análise , Hidrocarbonetos Policíclicos Aromáticos/toxicidade , Rios/química , Poluentes Químicos da Água/toxicidade , Animais , Brasil , Linhagem Celular , Citocromo P-450 CYP1A1/análise , Dioxinas/análise , Ecotoxicologia , Hidrocarbonetos Policíclicos Aromáticos/análise , Poluentes Químicos da Água/análiseRESUMO
The in vitro comet assay with the permanent fish cell line RTL-W1 and the in situ micronucleus assay using erythrocytes from indigenous tilapia (Oreochromis niloticus) were used to detect genotoxicity in Tietê River sediments (São Paulo, Brazil). Either test was successful in identifying site-specific differences in genotoxicity, with a high correlation between in situ and in vitro results indicating the relevance of the latter even for environmental studies. Discharges from São Paulo city have major impact on genotoxic effects by sediment-bound contaminants; however, overall genotoxicity decreases downstream. The high genotoxic burden of the Tietê River warrants measures to reduce the input of toxic effluents.