Ecotoxicidad de nanopartículas metálicas y superparamagnéticas de óxido de hierro en dos especies / Ecotoxicity of metalic and superparamagnetics iron oxide nanoparticles in two species

Introducción: la nanotecnología y el empleo de materiales a nano escala son un área relativamente nueva de la ciencia y la tecnología con un gran crecimiento en el mercado global. Muchos de los productos no cuentan con estudios que garanticen su uso seguro, tanto para el hombre como para los ecosistemas. Los estudios ecotoxicológicos permiten evaluar los efectos de un determinado xenobiótico sobre especies representativas de los diferentes compartimentos ambientales. Objetivo: evaluar los efectos tóxicos de nanopartículas de Ag, Au, Ag/Ag y superparamagnéticas de óxido de hierro, en dos especies bioindicadoras de los ecosistemas terrestre y acuático. Métodos: como parte de los estudios de seguridad se realizaron ensayos de toxicidad aguda por contacto en lombriz de tierra de la especie Eisenia andrei, con una duración de 96 horas y estudios en anfibios de la especie Osteopillus septentrionales en diferentes etapas del desarrollo (embrionario y larval). Se evaluó la ocurrencia de mortalidad y de efectos tóxicos, en el caso del ensayo en lombriz de tierra; se determinó además la viabilidad celular. Resultados: los efectos tóxicos más significativos en el caso de la lombriz de tierra fueron, la ocurrencia de alteraciones fisiológicas y conductuales al ser expuesta a NPs de Ag de 3 nm y superparamagnéticas de óxido de hierro, estas últimas provocaron citotoxicidad a la concentración 1,38 mg/mL. En el caso de los anfibios se evidenció toxicidad en NPs de Ag 3 nm y superparamagnéticas de óxido de hierro. Conclusiones: todas las nanopartículas mostraron efectos tóxicos en las especies bioindicadoras evaluadas(AU)

Introduction: Nanotechnology and the use of nanoscale materials are a relatively new area of science and technology with big growth in the global market. Many of these products don't have studies that guarantee their safe use, both for man and for ecosystems. Ecotoxicological studies allow the evaluation of the effects of a particular xenobiotic on representative species of the different environmental compartments. Objective: To evaluate the toxic effects of nanoparticles of Ag, Au, Ag / Ag and super paramagnetic iron oxide in two bioindicators of terrestrial and aquatic ecosystems. Methods: Acute contact toxicity tests were carried out on ground worm of the Eisenia andrei species, with a duration of 96 hours and studies on amphibians of the species Osteopillus septentrionales at different stages of development (embryonic and larval). The occurrence of mortality and toxic effects was evaluated in the case of earthworm test; cell viability was also determined. Results: The most significant toxic effects in the case of earthworms were the occurrence of physiological and behavioral alterations when exposed to 3 nm Ag of superparamagnetic iron oxide nanoparticles, where the latter caused cytotoxicity at concentration of 1.38 mg / mL. In the case of amphibians, toxicity was evidenced in Ag 3 nm nanoparticles and superparamagnetic iron oxide. Conclusions: All nanoparticles showed toxic effects in the evaluated bioindicator species(AU)

Mycoremediation of Congo red dye by filamentous fungi

Azo, anthroquinone and triphenylmethane dyes are the major classes of synthetic colourants, which are difficult to degrade and have received considerable attention. Congo red, a diazo dye, is considered as a xenobiotic compound, and is recalcitrant to biodegradative processes. Nevertheless, during the last few years it has been demonstrated that several fungi, under certain environmental conditions, are able to transfer azo dyes to non toxic products using laccases. The aim of this work was to study the factors influencing mycoremediation of Congo red. Several basidiomycetes and deuteromycetes species were tested for the decolourisation of Congo red (0.05 g/l) in a semi synthetic broth at static and shaking conditions. Poor decolourisation was observed when the dye acted as the sole source of nitrogen, whereas semi synthetic broth supplemented with fertilizer resulted in better decolourisation. Decolourisation of Congo red was checked in the presence of salts of heavy metals such as mercuric chloride, lead acetate and zinc sulphate. Decolourisation parameters such as temperature, pH, and rpm were optimized and the decolourisation obtained at optimized conditions varied between 29.25- 97.28 percent at static condition and 82.1- 100 percent at shaking condition. Sodium dodecyl sulphate polyacrylamide gel electrophoretic analysis revealed bands with molecular weights ranging between 66.5 to 71 kDa, a characteristic of the fungal laccases. High efficiency decolourisation of Congo red makes these fungal forms a promising choice in biological treatment of waste water containing Congo red.

Conceitos e derivação de valores de referência para biomonitorização humana de contaminantes ambientais / Concepts and determination of reference values for human biomonitoring of environmental contaminants

Human biomonitoring (HBM) of environmental contaminants plays an important role in estimating exposure and evaluating risk, and thus it has been increasingly applied in the environmental field. The results of HBM must be compared with reference values (RV). The term "reference values" has always been related to the interpretation of clinical laboratory tests. For physicians, RV indicate "normal values" or "limits of normal"; in turn, toxicologists prefer the terms "background values" or "baseline values" to refer to the presence of contaminants in biological fluids. This discrepancy leads to the discussion concerning which should be the population selected to determine RV. Whereas clinical chemistry employs an altered health state as the main exclusion criterion to select a reference population (that is, a "healthy" population would be selected), in environmental toxicology the exclusion criterion is the abnormal exposure to xenobiotics. Therefore, the choice of population to determine RV is based on the very purpose of the RV to be determined. The present paper discusses the concepts and methodology used to determine RV for biomarkers of chemical environmental contaminants.

Xenobiotics enhance laccase activity in alkali-tolerant gama-proteobacterium JB / Xenobióticos aumentam a atividade de lacase em gama-Proteobacterium JB alcali-tolerante

Various genotoxic textile dyes, xenobiotics, substrates (10 µM) and agrochemicals (100 µg/ml) were tested for enhancement of alkalophilic laccase activity inã-proteobacterium JB. Neutral Red, Indigo Carmine, Naphthol Base Bordears and Sulphast Ruby dyes increased the activity by 3.7, 2.7, 2.6 and 2.3 fold respectively. Xenobiotics/substrates like p-toluidine, 8-hydroxyquinoline and anthracine increased it by 3.4, 2.8 and 2.3 fold respectively. Atrazine and trycyclozole pesticides enhanced the activityby 1.95 and 1.5 fold respectively.

Vários corantes têxteis genotóxicos, xenobióticos, substratos (10 mM) e agroquímicos (100 mM/mL) foram testados quanto ao aumento da atividade de lacase em ã-Proteobacterium JB. Os corantes Neutral Red, Indigo Carmine, Naphtol Base Bordears e Sulphast Ruby aumentaram a atividade em 3,7, 2,7, 2,6 e 2,3 vezes, respectivamente. Xenobióticos/substratos como p-toluidina, 8-hidroxiquinolina e antracina aumentaram a atividade em 3,4, 2,8 e 2,3 vezes, respectivamente. Atrazina e pesticidas triciclozol aumentaram a atividade em 1,95 e 1,5 vezes, respectivamente.

Validacao de metodos cromatograficos em analises toxicologicas / Validation of chromatographic methods in toxicological analyses

A identificacao e quantificacao de xenobioticos em amostras biologicas pressupoe a utilizacao de metodologia cuja validacao tenha sido devidamente estabelecida. Agencias internacionais, tais como, Environmental Protection Agency, Food and Drug Administration, American Industry Hygiene Association, etc., responsaveis por programas de seguranca da qualidade em analises toxicologicas exigem relatos dos processos de validacao. A maxima "faca o que esta escrito e escreva o que e feito" mostra a enfase dada a tal documentacao. A validacao de um metodo analitico inclui todos os procedimentos realizados para garantir a qualidade dos dados produzidos. Independentemente do processo analitico a ser utilizado, preconiza-se um protocolo composto, basicamente, de tres estagios. O primeiro relaciona-se a procedimentos de afericao de instrumentos e calibracao de equipamentos visando assegurar a confiabilidade das medidas. O segundo diz respeito ao estudo da estabilidade do xenobiotico na matriz, considerando as condicoes de armazenamento e ciclos de congelamento e descongelamento, recuperacao, precisao, exatidao, limites de deteccao e quantificacao, especificidade e intervalo dinamico. O terceiro estagio baseia-se nos procedimentos adotados pelo laboratorio para garantir que o procedimento, como um todo, esta sob controle. Neste trabalho descrevem-se principios praticos e recomendacoes gerais no sentido de indicar diretrizes para o estabelecimento de protocolos que atestem a validade do resultado analitico