Avaliação do potencial de risco mutagênico dos poluentes presentes na exaustão de motor diesel por meio do bioensaio Trad-SH
Data
2017-11-15
Autores
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Biblioteca Digital de Teses e Dissertações da USP
Universidade de São Paulo
Escola de Engenharia de São Carlos
Universidade de São Paulo
Escola de Engenharia de São Carlos
Resumo
Descrição
A poluição atmosférica já é considerada um caso de saúde pública nos grandes centros urbanos. Freqüentemente as emissões veiculares são as principais causas dessa poluição, principalmente as provenientes dos motores diesel, os quais, além da produção de material particulado (MP), em cuja superfície são adsorvidas substâncias carcinogênicas e mutagênicas, produzem poluentes como os hidrocarbonetos policíclicos aromáticos (HPAs). Contudo não existe uma avaliação direta dos riscos dessas emissões nos seres vivos. Plantas bioindicadoras podem dar idéia desses riscos. Este trabalho teve como objetivo avaliar o potencial de risco mutagênico da exaustão proveniente de um motor diesel, utilizando o bioensaio Trad-SH (clone KU-20) como bioindicador da poluição do ar. Nos experimentos, a exaustão do motor diesel aspirado de 2.0 L de deslocamento volumétrico foi diluído com ar atmosférico de modo a atingir concentrações de uma atmosfera pesadamente poluída (aproximadamente 50, 100 e 150 ppm de CO). Obtidos estes níveis de diluição, as inflorescências foram expostas a esta mistura de poluentes por duas horas (doses agudas). A concentração de CO foi monitorada continuamente por meio de um analisador de gases Horiba Enda utilizando o princípio de absorção seletiva no infravermelho. Para se avaliar o efeito mutagênico foi feita uma comparação entre as inflorescências não expostas aos poluentes (grupo 1) e as inflorescências expostas (grupos 2, 3 e 4) com aproximadamente 50, 100 e 150 ppm de CO respectivamente. Os dados obtidos foram analisados estatisticamente observando-se que, a freqüência média das mutações no grupo 1 (controle), foi significativamente mais baixa do que aquela dos grupos 3 e 4, porém foi similar à do grupo 2. Por sua vez, não houve diferenças significativas nas freqüências de mutações entre os grupos 3 e 4. Os resultados indicam que a exaustão do motor a diesel teve um papel significativo no desenvolvimento de mutações, mas somente quando diluída para concentrações de CO acima de 100 ppm.
Air pollution caused by vehicle emission has been considered as a major public health concern in the urban centers. Emission from diesel engine powered vehicles, in particular, are highly toxic, since carcinogenic and mutagenic compounds can adsorb on the expelled particles leading to the formation of the so-called polycyclic aromatic hydrocarbons (PAH\'s). A detailed investigation on the risks of those compounds on the living beings using the methodology applied in the work has not been carried out so far. This work is aimed at evaluating the mutagenic potential of the emission from a diesel engine using the Tradescantia stamen hair assay (TSH), by monitoring the stamen hair mutation in the clone KU-20. Experimentally, the inflorescence of the KU-20 clones was kept for 2 h under a simulated urban heavily polluted atmosphere, obtained by mixing the emission from a diesel engine and atmospheric air. The CO concentration in the atmosphere was monitored using a Horiba-Enda gas analyzer. The mutagenic effects of the atmosphere were analyzed by comparing a group of non-exposed control inflorescence (group 1) to inflorescences kept under polluted atmospheres containing 50, 100 and 150 ppm of CO, assigned to as groups 2, 3 and 4. The experimental data were analyzed using statistical methods. The frequency of mutations observed in the inflorescences from group 2 was slightly higher than that observed in the group 1. In the groups 3 and 4, however, the frequency of mutations was significantly higher than that exhibited by the control group. The latter suggests that the emission from a diesel engine plays an important role in the development of plants mutation, specially for atmospheres containing more than 100 ppm of CO.
Air pollution caused by vehicle emission has been considered as a major public health concern in the urban centers. Emission from diesel engine powered vehicles, in particular, are highly toxic, since carcinogenic and mutagenic compounds can adsorb on the expelled particles leading to the formation of the so-called polycyclic aromatic hydrocarbons (PAH\'s). A detailed investigation on the risks of those compounds on the living beings using the methodology applied in the work has not been carried out so far. This work is aimed at evaluating the mutagenic potential of the emission from a diesel engine using the Tradescantia stamen hair assay (TSH), by monitoring the stamen hair mutation in the clone KU-20. Experimentally, the inflorescence of the KU-20 clones was kept for 2 h under a simulated urban heavily polluted atmosphere, obtained by mixing the emission from a diesel engine and atmospheric air. The CO concentration in the atmosphere was monitored using a Horiba-Enda gas analyzer. The mutagenic effects of the atmosphere were analyzed by comparing a group of non-exposed control inflorescence (group 1) to inflorescences kept under polluted atmospheres containing 50, 100 and 150 ppm of CO, assigned to as groups 2, 3 and 4. The experimental data were analyzed using statistical methods. The frequency of mutations observed in the inflorescences from group 2 was slightly higher than that observed in the group 1. In the groups 3 and 4, however, the frequency of mutations was significantly higher than that exhibited by the control group. The latter suggests that the emission from a diesel engine plays an important role in the development of plants mutation, specially for atmospheres containing more than 100 ppm of CO.
Palavras-chave
Poluição do ar, Poluente orgânico, Bioensaio Trad-SH, Motor diesel, Mutagenicidade, Organic pollutants, Mutagenic, Diesel engine, Bioassay Trad-SH, Air pollution