Evaluation of allowed parameters for nickel in freshwater bodies using the Allium cepa test

Abstract

Compostos de níquel são descartados em grandes quantidades no ambiente, fazendo dele um contaminante de relevância ecotoxicológica, uma vez que podem se bioacumular ao longo da cadeia trófica e/ou induzir danos genéticos aos organismos expostos. Nesse sentido, a legislação brasileira estabelece o limite máximo da concentração total de níquel permitida em corpos de água doce em 0,025 mg/l, que consiste em um quarto do estabelecido pela Agência de Proteção Ambiental dos Estados Unidos (EPA). O presente trabalho avaliou três concentrações de níquel, na forma de cloreto de níquel (NiCl2), tendo como referência àquela estabelecida como limite pela resolução 357/2005 do CONAMA (National Environmental Council), utilizando sementes de Allium cepa, com o intuito de mensurar o potencial tóxico, citotóxico, genotóxico e mutagênico deste elemento. Em tais concentrações, não foi verificada toxicidade ou citotoxicidade, ao passo que, para as três concentrações empregadas, observou-se a indução de efeitos genotóxicos e potencialmente mutagênicos, principalmente de células portadoras de micronúcleos, brotos e aderências cromossômicas. Dessa forma, infere-se que o cloreto de níquel possui ação aneugênica e/ou clastogênica. Esse estudo também serve de alerta para a contaminação aquática por metais, visto que a menor concentração utilizada e a permitida pela legislação brasileira induziram danos no organismo testado. Sugere-se a necessidade de revisar os parâmetros estabelecidos para este metal em corpos de água doce. Palavras-chave: Mutagênese ambiental. Metais pesados. Genotoxicidade. Mutagenicidade. AbstractNickel compounds are disposed in large amounts in the environment, making it an ecotoxicological relevant contaminant, since these can bioaccumulate along the food chain and/or can cause DNA damage to the exposed organisms. In this sense, Brazilian law establishes 0.025 mg/l as the utmost boundary for the total nickel concentration allowed in freshwater bodies that consists in a quarter of the established by United States Environmental Protection Agency (EPA). This study evaluated three nickel concentrations, in nickel chloride (NiCl2) shape, having as reference the limit established by CONAMA (National Environmental Council), using seeds of Allium cepa, in order to measure the cytotoxic, genotoxic and mutagenic potentials of this element. At such concentrations, it was not observed toxicity or cytotoxicity, whereas for all three concentrations employed, there was induction of genotoxic and potentially mutagenic effects, especially cells bearing micronuclei, buds and chromosome stickiness. Thus, it is inferred that nickel chloride has aneugenic and/or clastogenic action. This study is also an alert for the water contamination by metals, since both concentration used, the lowest one and the one permitted by Brazilian law induced damage to the tested organism. The study suggests the necessity of review in the established parameters for such metal in freshwater bodies.

Toxicity of two effluents from agricultural activity: Comparing the genotoxicity of sugar cane and orange vinasse

“…The metals aluminum, cobalt, copper, iron, manganese and nickel were measured in higher concentrations than allowed only in sugar cane vinasse. As for barium, these metals are also related to genotoxicity in different organisms (Boeck et al, 1998;Francisco et al, 2014;Lima et al, 2011;Van Goethem et al, 1997;Yildiz et al, 2009). In cells, metals lead to genotoxicity through different processes, but oxidative stress is the most common for nickel (Chen et al, 2003), copper (Thounaojam et al, 2012), cobalt (Alarifi et al, 2013) and iron (Ahamed et al, 2013).…”

Sugarcane Vinasse, a Residue of Ethanol Industry: Toxic, Cytotoxic and Genotoxic Potential Using the <i>Allium cepa</i> Test

“…The sensitivity of tests with A. cepa has been reported as superior in 82% of the results obtained with rodents [15]. Tests with A. cepa have received special attention, maily after being adapted to evaluate the effects of pollutants in the soil and water, such as metals [16], chemical compounds from industrial effluents [17] and pesticides [18] [19].…”