Mutagenic activity of airborne particulate matter from the urban area of Porto Alegre, Brazil

Abstract

The mutagenic activity of airborne particulate matter collected from three different sites within the urban area of Porto Alegre, Brazil, was investigated using a Salmonella/microsome assay. Samples were extracted by sonication, sequentially, with cyclohexane (CX), and dichloromethane (DCM), for a rough fractionation by polarity. The different fractions were tested for mutagenicity using Salmonella typhimurium strains TA98, with and without metabolic activation (S9 mix fraction), and TA98NR and TA98/1,8-DNP6, without metabolic activation. Mutagenic response was observed for frameshift strain TA98 in assays with and without metabolization for two sites (sites 2 and 3), which had considerable risk of environmental contamination by nonpolar (CX) and/or moderately polar (DCM) compounds. However, the values of revertants/m3 (rev/m3) were highest on the site subject to automobile exhaust (site 3) in assays without (9.56 rev/m3) and with metabolization (5.08 rev/m3). Maximum mutagenic activity was detected in the moderately polar fraction, decreasing after metabolization. Nevertheless, the nonpolar fractions (CX) gave higher mutagenic activity in the presence of metabolization than in the absence of the S9 mix fraction. The responses observed for TA98NR and TA98/1,8-DNP6 strains suggest the activity of nitrocompounds.<br>Foi investigada a atividade mutagênica de material particulado de amostras de ar coletadas em três diferentes locais dentro da área urbana da cidade de Porto Alegre, Brasil, através do ensaio Salmonella/microssoma. As amostras foram extraídas, em ultra-som, por fracionamento seqüencial de acordo com a polaridade, utilizando os solventes ciclohexano (CX) e diclorometano (DCM). As diferentes frações foram testadas para mutagenicidade com as linhagens de Salmonella typhimurium TA98, em presença e ausência de ativação metabólica, e TA98NR e TA98/1,8-DNP6 em ausência de metabolização. Observou-se resposta mutagênica positiva, do tipo erro no quadro de leitura, na linhagem TA98 (em ensaios em presença e ausência de metabolização) para compostos não polares (CX) e/ou moderadamente polares (DCM) nos locais com considerável risco de contaminação ambiental (locais 2 e 3). No entanto, os valores de revertentes por m3 (rev/m³) foram mais elevados no local sujeito a maior influência de veículos automotores (local 3), tanto em ensaios em ausência (9,56 rev/m³) como em presença de metabolização (5,08 rev/m³). A atividade mutagênica máxima foi detectada na fração moderadamente polar, decrescendo após metabolização. No entanto, as frações não polares (CX) apresentaram atividade mutagênica mais elevada na presença do que na ausência de fração S9mix. As respostas observadas para as linhagens TA98NR e TA98/1,8-DNP6 sugerem a contribuição de nitrocompostos na atividade mutagênica observada

Genetic Biomarkers Applied to Environmental Air Quality: Ecological and Human Health Aspects

“…One of these areas was under the specific influence of a petrochemical industry and another was influenced by contaminants from an oil refinery, but inserted in an urban area. The site studied in Porto Alegre city had been used as a reference for the urban area (RS, Brazil) presenting absence or low mutagenic activity in previous studies (Ducatti & Vargas, 2003;Vargas et al, 1998). These studies evaluated TSP organic extracts, which might account for the low mutagenic response, since the lowest particle fractions concentrate organic and mutagenic compounds (Hayakawa et al, 1995;Pagano et al, 1996).…”

“…Each pooled or simple sample was submitted to extraction by sonication with dichloromethane (DCM, CASRN. 75-09-2) (Vargas et al, 1998). Dichloromethane extracts the moderately polar compounds and is the most representative fraction of mutagenic activity (De Martinis et al, 1999) extracting a wide range of compounds from airborne particulate matter.…”

“…Studies in different areas of the city, airborne size fractions and periods were performed by our research group (Ducatti & Vargas, 2003;Vargas et al, 1998;Vargas, 2003). The area located in the Botanical Gardens District (30°03'12"S, 51°10'29"W) about 1 km from an avenue with traffic ranging from 72,000 to 120,000 vehicles/day during the studied periods, far from large industrial areas was selected to evaluate the mutagenicity of an urban area.…”

“…The studies reported were performed during three different periods using different particulate matter sizes: TSP (first period), Summer (December) of 1994 (Vargas et al, 1998), Spring (October) and Summer (December) of 1997 (Ducatti & Vargas, 2003;Vargas, 2003); PM10 (second period), Spring (October/November) and Summer (December) of 2006; PM2.5 (third period), Winter (August) and Spring (September/October) of 2010 ( Table 1). The first studies evaluated TSP (Ducatti & Vargas, 2003;Vargas et al, 1998;Vargas, 2003), and negative results were observed in most of the samples (Figure 2). The concentration of TSP particles agreed with what was expected for the area according to the institutional monitoring of air quality standards and below the legally established limit for Brazil (ranging from 17 to 60 µg/m 3 for October and December, respectively).…”

Seasonal variations in the level of mutagenicity: an assessment of respirable particulate matter in Rio de Janeiro, Brazil

“…Four monthly samplings were performed for each site. The filters were weighed and stabilized before and after samples (45% humidity) for the determination of particulate concentration, expressed in µg/m 3 units of sampled air [12][13][14]. At the end of the sampling, the filters were combined to form a pool sample.…”