ABSTRACT. Risk assessment can provide a comprehensive estimate of potential effects of contaminants under specific, well-defined, and well-described circumstances, providing quantitative relationships between exposure and effects to identify and to define areas of concern. We investigated the mutagenic activity of particulate matter in air samples collected from three sites in Rio de Janeiro city. Samples were collected using a high-volume sampler at Avenida Brasil, at Campus of Universidade do Estado do Rio de Janeiro, and at Rebouças Tunnel. Six polycyclic aromatic hydrocarbons were quantified by gas chromatography/mass spectrometry. Salmonella typhimurium TA98 and the derivative strains TA98/1.8-DNP 6 , YG1021, and YG1024, Health risk in urban airborne in Rio de Janeiro commonly used in mutagenicity assays, were treated (10-50 µg/plate), with and without exogenous metabolization. The highest values for the polycyclic aromatic hydrocarbons were detected at Rebouças Tunnel. For chrysene, as an example, the concentration was nearly 200 times higher than that established by the US Environmental Protection Agency. Frequent traffic jams can place bus drivers who go through the Rebouças Tunnel at risk of exposure to up to 0.69 ng/m 3 benzo(a) pyrene. Independent of exogenous metabolization, mutagenicity was detected in strains YG1021 and YG1024 at all the sites, suggesting nitro and amino derivatives of polycyclic aromatic hydrocarbons. Rebouças Tunnel air samples gave the highest values for rev/µg and rev/m 3 . This could be due to the fact that the long, enclosed passageway through a mountain restricts ventilation. The cancer risk estimate in this study was 10 -3 for the benzo(a)pyrene, at the two sites, indicating a high risk.

Air pollution toxic effects are mainly attributed to small inhalable particulates with an aerodynamic diameter of less than 2.5 µm (PM 2.5). Our objective was to investigate mutagenic and clastogenic activity in PM samples collected in Rio de Janeiro. Samples were collected using a high-volume sampler at three sites: with low traffic and (2) and (3) with a heavy traffic. Six polycyclic aromatic hydrocarbons (PAHs) were quantified by gas chromatography/mass spectrometry (GC/MS). Salmonella typhimurium TA98 and the derivative strains YG1021 and YG1024 were used in mutagenicity assays in the presence of organic extracts (10–50 µg/ plate) with and without exogenous metabolization. Allium cepa test was performed to evaluate possible cytotoxic and clastogenic activities. The highest PM 2.5 µm (132.73 µm/m3) and PAH values (1.22 ng/m3 for benzo(a)pyrene) were detected at site 3. High mutagenic frameshift responses in absence and presence of metabolic activation were detected at site 3. The participation of nitroarenes and dinitroarenes was detected in the total mutagenicity of the extracts studied. The cytotoxic effect and the abnormalities detected by Allium cepa test can be attributed to the PAH nitroderivatives in the organic extracts. Evaluation of the genotoxicity of urban airborne particulate matter is important as a basis for decision making by regulatory authorities.

N -nitroso compounds, such as N -nitrosodiethylamine (NDEA), can be formed by the reaction of secundary amines with nitrosating agents, and are suspected to be involved in tumors in humans. NDEA has been considered a weak carcinogen in genotoxic assays probably due to the inefficient nitrosamine activation system that is used and/or to the efficient repair system. In this work, we evaluated the sensibility of Allium cepa L. root tips and Tradescantia stamen hair mutation assay (Trad-SH) using Tradescantia pallida var. purpurea for NDEA (0.1; 0.5; 5 and 25mM) genotoxicity and mutagenicity induction. Allium cepa L. was treated with different NDEA concentrations for 3h, for 3 consecutive days, including negative control (distilled water) and positive control maleic hydrazide (MH 30μg/mL). After treatment, the roots were hydrolyzed, squashed, and the mitotic index (MI) and cytological abnormalities were scored. The results revealed a cytostatic effect of NDEA (0.5 and 5mM), showing a significant reduction in the MI. Chromosome stickiness suggests a NDEA toxic effect. T. pallida purpurea did not respond to mutagens with a dosedependent pattern. In conclusion, our study indicates that the root tips of Allium cepa L. have sensibility to detect NDEA genotoxicity, but not for Trad-SH test.

Several epidemiological studies have associated PM2.5 (particulate matter, aerodynamic diameter 2.5 µm) exposure with an increase in morbidity and mortality attributed to cardiopulmonary diseases. Based upon these observations and the growing effort to replace the use of animals in research, in vitro A549 cells cultured in three dimensions (3D), an alternative method to the use of animals, as well as monolayers were investigated to examine whether organic PM2.5 extract induced equivalent cytotoxic changes in vitro as compared to in vivo. PM2.5 was collected on Brazil Avenue, Rio de Janeiro, Brazil, from November 2010 to May 2011, except March, and analyzed for the ability to induce cytotoxicity in A549 cells using various established assays. Samples collected in all months significantly decreased viability of A549 cells using both types of cell death assays, and those collected in November showed lower cytotoxicity. It is worthwhile noting that for samples collected in all months except for April, PM2.5 induced greater toxicity in cells grown in monolayers than in 3D. Data demonstrated that cell behavior varied based upon type of culture system employed. Since the 3D cell culture mimics the architecture of in vivo tissue to a greater extent than monolayers, it is suggested that data from 3D studies resemble more closely human exposure conditions and thus may provide more reliable findings to be utilized in risk assessment following PM exposure than results obtained in traditional culture system.

Respirable particles (PM2.5) can become associated with organic matter containing several compounds such as polycyclic aromatic hydrocarbons (PAHs). Many PAHs have been identified as cancer-inducing chemicals. The mutagenicity of airborne particles is generally associated with PAHs, but recent reviews show that PAHs may not be the predominant mutagens in atmospheric pollution, and that nitroaromatic compounds, aromatic amines and aromatic ketones, often found in moderately polar or highly polar organic fractions, are potent mutagens. Nitro-polycyclicaromatics (nitro-PAHs) are persistent environmental mutagens and can be found in airborne suspended particles from direct sources such as diesel and gasoline exhausts, or may be products of atmospheric reactions in the presence of NO 2 and NO 3 radicals. In the present work we compared PAH levels and mutagenicity using gas chromatography spectrometry and the Salmonella/microsome assay on organic extracts of PM2.5 for Salmonella typhimurium strain TA98. The samples were collected in two periods: (I) July to October 2010 and (II) November 2010 to May 2011 at three sites in Rio de Janeiro -(1) low urban traffic at the University campus; (2) heavy . Mutagenic frameshift responses in the absence of metabolic activation were detected at all the sites in periods I and II. In the presence of metabolic activation this response was observed for all three sites in period I, but only for site 3 in period II. Nitroarenes and dinitroarenes were detected at all three sites in period I. In period II, the presence of nitroarenes was also detected at all sites, but dinitroarenes were only detected at sites 2 and 3. The information generated in this study shows that different levels of PAHs and nitroderivatives, influenced by seasonal variations in climatic conditions, probably contribute to the detected airborne mutagenicity.

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ABSTRACT. The use of strains of Salmonella enterica serovar Typhimurium with different metabolic capacities can indicate the class or classes of compounds present in an environmental sample and enable the diagnosis of the mutagenic activity of these pollutants adsorbed on particulate matter (PM) in the air. In the present study, the sensitivity of Salmonella strains TA98NR, TA98/1,8-DNP 6 , YG1021, and YG1024 to detect nitro compounds adsorbed on samples of PM 2.5 was compared from three sites in Rio de Janeiro city. Samples were collected using a high-volume sampler at three sites: one with light traffic and two with heavy traffic. The assays were performed in the presence of 10-50 μg/ plate organic extracts with and without exogenous metabolization. The YG1021 and YG1024 strains showed the highest rev/m 3 values, confirming their enhanced sensitivity. As YG1024 also demonstrated sensitivity to nitro and amino compounds, we suggest its use in research into environmental contamination.

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