Mutagenicity of airborne particulate organic material from urban and industrial areas of São Paulo, Brazil

A comprehensive overview of genotoxicity and mutagenicity associated with outdoor air pollution exposure in Brazil

This review examined the mutagenicity and genotoxicity associated with exposure to outdoor air pollutants in Brazil. A search was performed on the Web of Science database using a combination of keywords that resulted in 134 articles. After applying exclusion criteria, a total of 75 articles were obtained. The articles were classified into three categories: (1) studies with plants and animals, (2) in vitro studies, and (3) human biomonitoring. The investigations were conducted in 11 of 27 Brazilian states with the highest prevalence in the southeast and south regions. Only 5 investigations focused on the effects of burning biomass on the quality of outdoor air. Plants, especially Tradescantia pallida, were the main air pollution biomonitoring tool. When available, a significant association between levels of air pollutants and genetic damage was described. Among the in vitro studies, Salmonella/microsome is the most used test to evaluate mutagenesis of outdoor air in Brazil (n = 26). Human biomonitoring studies were the least frequent category (n = 18). Most of the investigations utilized micronucleus bioassay, in oral mucosa cells (n = 15) and lymphocytes (n = 5), and the comet assay (n = 6). The analysis in this study points to the existence of gaps in genotoxicity studies and our findings indicate that future studies need to address the variety of potential sources of pollution existing in Brazil. In addition to extent of the impacts, consideration should be given to the enormous Brazilian biodiversity, as well as the determination of the role of socioeconomic inequality of the population in the observed outcomes.

Genotoxicity of organic material extracted from particulate matter of alternative fuels

Global demand for energy is rapidly increasing, and resources for the production of petroleum-based fuels are running out. For this, renewable fuels like biodiesel and hydrotreated vegetable oil biofuel are considered important alternatives to replace such fuels. In this study, we evaluated the in vitro genotoxicity effect on HepG2 cells of organic material extracted from particulate matter emissions of an engine fueled with conventional diesel or mixtures of diesel with 10% of biomass. The emissions were collected in two operational modes, 2410 rpm (slope simulation) and 1890 rpm (plane). Genotoxicity was evaluated through two methods, chromosomal aberration test and the alkaline comet assay. The former did not show any genotoxic effect, but the latter exhibited a statistically significant effect despite the operational mode of the engine and the concentration organic material extracted. In conclusion, regardless of the concentration of organic material extracted from particulate matter, the operational mode of the engine, or the fuel used, a significant damage of the DNA was found. In general, at the physicochemical level, a decrease in the amount of emissions of the used fuels is not directly related to a decrease in the genotoxicity potential.

Similar polycyclic aromatic hydrocarbon and genotoxicity profiles of atmospheric particulate matter from cities on three different continents

The extractable organic material (EOM) from atmospheric total suspended particles (TSP) contains several organic compounds including non-substituted polycyclic aromatic hydrocarbons (PAHs), alkyl-PAHs, and nitro-PAHs. These chemicals seem to be among the key drivers of TSP genotoxicity. We have shown previously that the mutagenic potencies of the EOM from Limeira, Stockholm, and Kyoto, cities with markedly different meteorological conditions and pollution sources are similar. Here we compare the profiles of non-substituted PAHs (27 congeners), alkyl-PAHs (15 congeners), and nitro-PAHs (7 congeners) from the same EOM samples from these cities. We also compared the genotoxicity profiles using comet and micronucleus assays in human bronchial epithelial cells. The profiles of PAHs, as well as the cytotoxic and genotoxic potencies when expressed in EOM, were quite similar among the studied cities. It seems that despite the differences in meteorological conditions and pollution sources of the cities, removal, mixing, and different atmospheric transformation processes may be contributing to the similarity of the PAHs composition and genotoxicity profiles. More studies are required to verify if this would be a general rule applicable to other cities. Although these profiles were similar for all three cities, the EOM concentration in the atmospheres is markedly different. Thus, the population of Limeira (∼10-fold more EOM/m³ than Stockholm and ∼6-fold more than Kyoto) is exposed to higher concentrations of genotoxic pollutants, and Kyoto's population is 1.5-fold more exposed than Stockholm's. Therefore, to reduce the risk of human exposure to TSP genotoxins, the volume of emissions needs to be reduced.

Mutagenicity as a parameter in surface water monitoring programs-opportunity for water quality improvement

Effect-based analyses are being recognized as excellent tools to a comprehensive and reliable water quality evaluation to complement physical and chemical parameters. The Salmonella/microsome mutagenicity test was introduced in the São Paulo State water quality-monitoring program in 1999 and waters from 104 sites used to the production of drinking water were analyzed. Samples were tested after organic extraction, using the microsuspension version of the Salmonella/microsome assay with strains TA98 and TA100 with and without S9-mammalian metabolic system. Of the 1720 water samples analyzed in 20 years, 20% were positive; TA98 was the most sensitive strain, detecting alone 99%. Results were presented in hazard categories to facilitate water managers' understanding and general public communication. Hot spots of mutagenicity were identified, and pollution sources investigated. A flow scheme with instructions of how to proceed in case of mutagenic samples was developed and implemented in the monitoring program. Enforcement actions were taken to reduce exposure of humans and aquatic biota to mutagenic compounds. The results presented provide scientific basis for the incorporation of the Salmonella/microsome assay in a regulatory framework, and to guide water-quality managers. The inclusion of a mutagenicity assay using standardized conditions proved to be an opportunity to improve the quality of water, and the strategy presented here could be applied by any environmental agency around the world. Environ. Mol. Mutagen. 61:200-211, 2020. © 2019 Wiley Periodicals, Inc.

Comparative mutagenic activity of atmospheric particulate matter from limeira, stockholm, and kyoto

Atmospheric particulate matter (PM) organic fractions from urban centers are frequently mutagenic for the Salmonella/microsome assay. This mutagenicity is related to both primary and secondary pollutants, and meteorological conditions have great influence on the secondary pollutant's formation. Our objective was to compare the mutagenicity of atmospheric total suspended particulates (TSP) from three cities with marked different meteorological conditions and TSP concentrations: Limeira (Brazil) with 99.0 μg/m³ , Stockholm (Sweden) with 6.2 μg/m³ , and Kyoto (Japan) with 28.0 μg/m³ . For comparison, we used the same batch of filters, sample extraction method, and Salmonella/microsome testing protocol with 11 strains of Salmonella with and without metabolic activation. Samples were collected during winter and pooled into one single extract representing each city. All samples were mutagenic for all tested strains, except for TA102. Based on the strain's selectivity, nitroarenes, polycyclic aromatic hydrocarbons, and aromatic amines play a predominant role in the mutagenicity of these samples. The mutagenic potencies expressed by mass of extracted organic material (EOM; revertants/μg EOM) were similar (~twofold difference) among the cities, despite differences in meteorological conditions and pollution sources. In contrast, the mutagenic potencies expressed by air volume (rev/m³ ) varied ~20-fold, with Limeira > Kyoto ≈ Stockholm. These results are the first systematic assessment of air mutagenicity from cities on three continents using the same protocols. The results confirm that the mutagenic potency expressed by EOM mass is similar regardless of continent of origin, whereas the mutagenic potency expressed by air volume can vary by orders of magnitude. Environ. Mol. Mutagen. 2019. © 2019 Wiley Periodicals, Inc.

Effect of urbanization on the micronucleus frequency in birds from forest fragments

The urbanization contributes to environment contamination, mainly by the increased vehicle traffic. This intense traffic releases in the air chemical compounds with mutagenic properties that can affect the entire ecosystem. The birds for the flight accumulate air, absorbing gases or particles. The absorption of this polluted air may be causative agent responsible for micronucleus (MN) induction in bird erythrocytes. The quantitative analysis of MN in birds can assists in the monitoring environmental quality of various places. The study aimed to quantify the MN frequency in birds and compare their variation: I) among forest fragments distant from and near to urbanization, II) among species and populations of birds and III) to find if there is a relation between vehicle traffic and MN induction. The capture of the birds took place in four forest fragments in central Brazil (two distant and two near the city) using mist nets. Blood smears were prepared with blood collected from the tarso-metatarsal vein. A total of 354 individuals were analyzed and MN were found in 52% of the individuals analyzed. All sampled birds were identified and resulted to belong to 50 different species, only 4 of which were captured in all the 4 forest fragments. The average MN frequency, regardless of bird species and sampling area, was 1.04/10,000 erythrocytes. From an overall analysis carried out on all birds, the MN frequencies were found to vary among forest fragments distant from and near to urbanization (x² =15.513; p < 0.001) and demonstrated positive correlation between vehicle traffic intensity and the MN frequency (r = 0.988; df=2; p = 0.011). The species of birds presented variation in the amount of MN (x² = 84.64; df=49; p = 0.001). Therefore, a restricted analysis carried out on the 4 species of birds present in all the forest fragments showed that the populations of Antilophia galeata (x² =6.029; p = 0.014), Basileuterus culicivorus (x² =9.53; p = 0.002), Eucometis penicillata (x² =8.067; p = 0.005) and Myiothlypis flaveola (x² =4.771; p = 0.029) showed difference in the MN frequency, when compared between forest fragments distant from and near to cities. The analysis demonstrated that birds living in forest areas near to the city presented higher MN frequency, probably because pollutants generated by urbanization affect birds and that the larger the vehicle traffic the greater the induced MN in the birds.

Mutagenicity profile of atmospheric particulate matter in a small urban center subjected to airborne emission from vehicle traffic and sugar cane burning

Atmospheric particulate matter (PM) is genotoxic and recently was classified as carcinogenic to humans by the International Agency for Research on Cancer. PM chemical composition varies depending on source and atmospheric conditions. The Salmonella/microsome assay is the most used mutagenicity test and can identify the major chemical classes responsible for observed mutagenicity. The objective of this work was to characterize the mutagenicity of PM samples from a countryside city, Limeira, Brazil, which is influenced by heavy traffic and sugar cane biomass burning. Six samples of total PM were collected. Air mass backward trajectories were calculated. Organic extracts were assayed using the Salmonella/microsome microsuspension mutagenicity assay using TA98, YG1041, and TA1538, with and without metabolic activation (S9). YG1041 was the most sensitive strain and mutagenicity reached 9,700 revertants per m(3) without metabolic activation. Potency for TA1538 was higher than TA98, indicating that this strain should be considered in air mutagenicity studies. The increased response to YG1041 relative to TA98, and the decreased response with S9, suggests that nitroaromatics are the major contributors. Limeira is among the most mutagenic cities in the world. High mutagenicity in Limeira seems to occur when the air mass from the area of sugarcane production is mixed with air from the region impacted by anthropogenic activities such as traffic. An increase in the formation of nitro-polycyclic aromatic hydrocarbons may result from longer contact time between the aromatic compounds and the atmosphere with high NOx and ozone concentration, although more studies are required to confirm this hypothesis.

Sensitivity of Salmonella YG5161 for detecting PAH-associated mutagenicity in air particulate matter

The Salmonella/microsome assay is the most used assay for the evaluation of air particulate matter (PM) mutagenicity and a positive correlation between strain TA98 responses and benzo[a]pyrene (B[a]P) levels in PM has been found. However, it seems that the major causes of PM mutagenicity in this assay are the nitro and oxy-PAHs. Salmonella YG5161, a 30-times more responsive strain to B[a]P has been developed. To verify if YG5161 strain was sufficiently sensitive to detect mutagenicity associated with B[a]P mutagenicity, PM samples were collected in Brazil and Sweden, extracted with toluene and tested in the Salmonella/microsome microsuspension assay. PAHs and B[a]P were determined and the extracts were tested with YG5161 and its parental strain TA1538. The extracts were also tested with YG1041 and its parental strain TA98. For sensitivity comparisons, we tested B[a]P and 1-nitropyrene (1-NP) using the same conditions. The minimal effective dose of B[a]P was 155 ng/plate for TA1538 and 7 ng/plate for YG5161. Although the maximum tested dose, 10 m(3) /plate containing 9 ng of B[a]P in the case of Brazilian sample, was sufficient to elicit a response in YG5161, mutagenicity was detected at a dose as low as 1 m(3) /plate (0.9 ng). This is probably caused by nitro-compounds that have been shown to be even more potent than B[a]P for YG5161. It seems that the mutagenicity of B[a]P present in PM is not detectable even with the use of YG5161 unless more efficient separation to remove the nitro-compounds from the PAH extract is performed.

Genetic damage of organic matter in the Brazilian Amazon: a comparative study between intense and moderate biomass burning

BACKGROUND

The biomass burning that occurs in the Amazon region has an adverse effect on environmental and human health. However, in this region, there are limited studies linking atmospheric pollution and genetic damage.

OBJECTIVE

We conducted a comparative study during intense and moderate biomass burning periods focusing on the genetic damage and physicochemical analyses of the particulate matter (PM).

METHOD

PM and black carbon (BC) were determined; organic compounds were identified and quantified using gas chromatography with flame ionization detection, the cyto-genotoxicity test was performed using two bioassays: cytokinesis-block micronucleus (CBMN) in A549 cells and Tradescantia pallida micronucleus (Trad-MCN) assay.

RESULTS

The PM10 concentrations were lower than the World Health Organization air quality standard for 24h. The n-alkanes analyses indicate anthropogenic and biogenic influences during intense and moderate biomass burning periods, respectively. Retene was identified as the most abundant polycyclic aromatic hydrocarbon during both sampling periods. Carcinogenic and mutagenic compounds were identified. The genotoxic analysis through CBMN and Trad-MCN tests showed that the frequency MCN from the intense burning period is significantly higher compared to moderate burning period.

CONCLUSIONS

This is the first study using human alveolar cells to show the genotoxic effects of organic PM from biomass burning samples collected in Amazon region. The genotoxicity of PM can be associated with the presence of several mutagenic and carcinogenic compounds, mainly benzo[a]pyrene. These findings have potential implications for the development of pollution abatement strategies and can minimize negative impact on health.

Genotoxicity of polycyclic aromatic hydrocarbons and nitro-derived in respirable airborne particulate matter collected from urban areas of Rio de Janeiro (Brazil)

Air pollution toxic effects are mainly attributed to small inhalable particulates with an aerodynamic diameter of less than 2.5 µ m (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 µ g/ plate) with and without exogenous metabolization. Allium cepa test was performed to evaluate possible cytotoxic and clastogenic activities. The highest PM 2.5 µ m (132.73 µ m/m(3)) and PAH values (1.22 ng/m(3) 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.

The azo dye Disperse Orange 1 induces DNA damage and cytotoxic effects but does not cause ecotoxic effects in Daphnia similis and Vibrio fischeri

Azo dyes constitute the largest group of colorants used in industry and can pass through municipal waste water plants nearly unchanged due to their resistance to aerobic treatment, which potentially exposes humans and local biota to adverse effects. Unfortunately, little is known about their environmental fate. Under anaerobic conditions, some azo dyes are cleaved by microorganisms forming potentially carcinogenic aromatic amines. In the present study, the azo dye Disperse Orange 1, widely used in textile dyeing, was tested using the comet, Salmonella/microsome mutagenicity, cell viability, Daphnia similis and Microtox(®) assays. The human hepatoma cell line (HepG2) was used in the comet assay and for cell viability. In the mutagenicity assay, Salmonella typhimurium strains with different levels of nitroreductase and o-acetyltransferase were used. The dye showed genotoxic effects with respect to HepG2 cells at concentrations of 0.2, 0.4, 1.0, 2.0 and 4.0μg/mL. In the mutagenicity assay, greater responses were obtained with the strains TA98 and YG1041, suggesting that this compound mainly induces frameshift mutations. Moreover, the mutagenicity was greatly enhanced with the strains overproducing nitroreductase and o-acetyltransferase, showing the importance of these enzymes in the mutagenicity of this dye. In addition, the compound induced apoptosis after 72h in contact with the HepG2 cells. No toxic effects were observed for either D. similis or Vibrio fischeri.

Determination of anthropogenic and biogenic compounds on atmospheric aerosol collected in urban, biomass burning and forest areas in São Paulo, Brazil

This study was conducted at three sites of different characteristics in São Paulo State: São Paulo (SPA), Piracicaba (PRB) and Mata Atlântica Forest (MAT). PM(10), n-alkanes, pristane and phytane, PAHs, water-soluble ions and biomass burning tracers like levoglucosan and retene, were determined in quartz fiber filters. Samplings occurred on May 8th to August 8th, 2007 at the MAT site; on August 15th to 29th in 2007 and November 10th to 29th in 2008 at the PRB site and, March 13th to April 4th in 2007 and August 7th to 29th in 2008 at the SPA site. Aliphatic compounds emitted biogenically were less abundant at the urban sites than at the forest site, and its distribution showed the influence of tropical vascular plants. Air mass transport from biomass burning regions is likely to impact the sites with specific molecular markers. The concentrations of all species were variable and dependent of seasonal changes. In the most dry and polluted seasons, n-alkane and cation total concentrations were similar between the megacity and the biomass burning site. PAHs and inorganic ion abundances were higher at São Paulo than Piracicaba, yet, the site influenced by biomass burning seems to be the most impacted by the organic anion abundance in the atmosphere. Pristane and phytane confirm the contamination by petroleum residues at urban sites; at the MAT site, biological activity and long range transport of pollutants might influence the levels of pristane.

Comparison of the Salmonella/microsome microsuspension assay with the new microplate fluctuation protocol for testing the mutagenicity of environmental samples

The objective of this study was to compare the responses of the Salmonella/microsome microsuspension assay with the new microplate fluctuation protocol (MPF) for the evaluation of the mutagenic activity of environmental samples. Organic extracts of total particulate atmospheric air samples, surface waters, and effluents were tested in dose-response experiments. The assays were performed with strain TA98 in the absence and presence of S9 mix. Both protocols produced similar results, despite the fact that the maximum score of the MPF is limited to 48 wells, whereas in the regular plate assay it is possible to count up to 1,500 colonies using an automatic counter. Similar sensitivities based on the lowest dose that resulted in a positive response were obtained for both assays. The MPF procedure is less laborious (e.g., all-liquid format, use of multichannel pipettors) and allows for automation of the pipetting and dispensing steps, thus, reducing time of the analysis which is particularly important in environmental quality monitoring programs or in effect-directed analysis. The results show that the MPF procedure is a promising tool to test environmental samples for mutagenic activity.

A preliminary characterization of the mutagenicity of atmospheric particulate matter collected during sugar cane harvesting using the Salmonella/microsome microsuspension assay

During sugar cane harvesting season, which occurs from May to November of each year, the crops are burnt, cut, and transported to the mills. There are reports showing that mutagenic activity and PAH content increase during harvesting season in some areas of São Paulo State in comparison with nonharvesting periods. The objective of this work was to preliminarily characterize the mutagenic activity of the total organic extracts as well as corresponding organic fractions of airborne particulate matter (PM) collected twice from two cities, Araraquara (ARQ) and Piracicaba (PRB), during sugar cane harvesting season using the Salmonella/microsome microssuspension assay. One sample collected in São Paulo metropolitan area was also included. The mutagenicity of the total extracts ranged from 55 to 320 revertants per cubic meter without the addition of S9 and from not detected to 57 revertants per cubic meter in the presence of S9 in areas with sugar cane plantations. Of the three fractions analyzed, the most polar ones (nitro and oxy) were the most potent. A comparison of the response of TA98 with YG1041 and the increased potencies without S9 indicated that nitro compounds are causing the observed effect. More studies are necessary to verify the sources of the mutagenic activity such as burning of vegetal biomass and combustion of heavy duty vehicles used to transport the sugar cane to the mills. The Salmonella/microsome assay can be an important tool to monitor the atmosphere for mutagenicity during sugar cane harvesting season.

Mutagenicity and DNA adduct formation of PAH, nitro-PAH, and oxy-PAH fractions of atmospheric particulate matter from São Paulo, Brazil

Urban particulate matter (UPM) contributes to lung cancer incidence. Here, we have studied the mutagenic activity and DNA adduct-forming ability of fractionated UPM extractable organic matter (EOM). UPM was collected with a high-volume sampler in June 2004 at two sites, one at street level adjacent to a roadway and the other inside a park within the urban area of the city of São Paulo, Brazil. UPM was extracted using dichloromethane, and the resulting EOM was separated by HPLC to obtain PAH, nitro-PAH, and oxy-PAH fractions which were tested for mutagenicity with the Salmonella strains TA98 and YG1041 with and without S9 metabolic activation. The PAH fraction from both sites showed negligible mutagenic activity in both strains. The highest mutagenic activity was found for the nitro-PAH fraction using YG1041 without metabolic activation; however, results were comparable for both sites. The nitro-PAH and oxy-PAH fractions were incubated with calf thymus DNA under reductive conditions appropriate for the activation of nitro aromatic compounds, then DNA adduct patterns and levels were determined with thin-layer chromatography (TLC) 32P-postlabeling method using two enrichment procedures-nuclease P1 digestion and butanol extraction. Reductively activated fractions from both sites produced diagonal radioactive zones (DRZ) of putative aromatic DNA adducts on thin layer plates with both enrichment procedures. No such DRZ were observed in control experiments using fractions from unexposed filters or from incubations without activating system. Total adduct levels produced by the nitro-PAH fractions were similar for both sites ranging from 30 to 45 adducts per 10(8) normal nucleotides. In contrast, the DNA binding of reductively activated oxy-PAH fractions was three times higher and the adduct pattern consisted of multiple discrete spots along the diagonal line on the thin layer plates. However, DNA adduct levels were not significantly different between the sampling sites. Both samples presented the same levels of mutagenic activity. The response in the Salmonella assay was typical of nitroaromatics. Although, more mutagenic activity was related to the nitro-PAH fraction in the Salmonella assay, the oxy-PAH fractions showed the highest DNA adduct levels. More studies are needed to elucidate the nature of the genotoxicants occurring in São Paulo atmospheric samples.

Effects of genetic polymorphisms CYP1A1, GSTM1, GSTT1 and GSTP1 on urinary 1-hydroxypyrene levels in sugarcane workers

Sugarcane workers in Brazil are exposed to various genotoxic compounds, including polycyclic aromatic hydrocarbons (PAHs), derived from an incomplete combustion process of burnt sugarcane fields. The effects of the occupational exposure to sugarcane fields burning were measured in urine samples of sugarcane workers from the northwest of the State of São Paulo when exposed (harvesting) and when non-exposed (non-harvesting). The urinary levels of 1-hydroxypyrene (1-OHP) and the influence of the genetic polymorphisms CYP1A1, GSTM1, GSTT1 and GSTP1 were evaluated. Our results showed that the 1-OHP levels were significantly higher (P<0.0000) in the exposed sugarcane workers (0.318 mumol mol(-1) creatinine) than in the non-exposed workers (0.035 mumol mol(-1) creatinine). In an unvaried analysis, no influence regarding the polymorphisms was observed. However, multivariate regression analysis showed that the CYP1A1()4 polymorphism in the exposed group, and age and the GSTP1 polymorphism in the non-exposed group significantly influenced urinary 1-OHP excretion levels (P<0.10). The same group of sugarcane workers was significantly more exposed to PAHs during the harvesting period than during the non-harvesting period.

Toxicological assessment of ambient and traffic-related particulate matter: a review of recent studies

Particulate air pollution (PM) is an important environmental health risk factor for many different diseases. This is indicated by numerous epidemiological studies on associations between PM exposure and occurrence of acute respiratory infections, lung cancer and chronic respiratory and cardiovascular diseases. The biological mechanisms behind these associations are not fully understood, but the results of in vitro toxicological research have shown that PM induces several types of adverse cellular effects, including cytotoxicity, mutagenicity, DNA damage and stimulation of proinflammatory cytokine production. Because traffic is an important source of PM emission, it seems obvious that traffic intensity has an important impact on both quantitative and qualitative aspects of ambient PM, including its chemical, physical and toxicological characteristics. In this review, the results are summarized of the most recent studies investigating physical and chemical characteristics of ambient and traffic-related PM in relation to its toxicological activity. This evaluation shows that, in general, the smaller PM size fractions (<PM(10)) have the highest toxicity, contain higher concentrations of extractable organic matter (comprising a wide spectrum of chemical substances), and possess a relatively high radical-generating capacity. Also, associations between chemical characteristics and PM toxicity tend to be stronger for the smaller PM size fractions. Most importantly, traffic intensity does not always explain local differences in PM toxicity, and these differences are not necessarily related to PM mass concentrations. This implies that PM regulatory strategies should take PM-size fractions smaller than PM(10) into account. Therefore, future research should aim at establishing the relationship between toxicity of these smaller fractions in relation to their specific sources.

Genotoxicity and physicochemical characteristics of traffic-related ambient particulate matter

Exposure to ambient particulate matter (PM) has been linked to several adverse health effects. Since vehicular traffic is a PM source of growing importance, we sampled total suspended particulate (TSP), PM(10), and PM(2.5) at six urban locations with pronounced differences in traffic intensity. The mutagenicity, DNA-adduct formation, and induction of oxidative DNA damage by the samples were studied as genotoxicological parameters, in relation to polycyclic aromatic hydrocarbon (PAH) levels, elemental composition, and radical-generating capacity (RGC) as chemical characteristics. We found pronounced differences in the genotoxicity and chemical characteristics of PM from the various locations, although we could not establish a correlation between traffic intensity and any of these characteristics for any of the PM size fractions. Therefore, the differences between locations may be due to local sources of PM, other than traffic. The concentration of total (carcinogenic) PAHs correlated positively with RGC, direct and S9-mediated mutagenicity, as well as the induction of DNA adducts and oxidative DNA damage. The interaction between total PAHs and transition metals correlated positively with DNA-adduct formation, particularly from the PM(2.5) fraction. RGC was not associated with one specific PM size fraction, but mutagenicity and DNA reactivity after metabolic activation were relatively high in PM(10) and PM(2.5), when compared with TSP. We conclude that the toxicological characteristics of urban PM samples show pronounced differences, even when PM concentrations at the sample sites are comparable. This implies that emission reduction strategies that take chemical and toxicological characteristics of PM into account may be useful for reducing the health risks associated with PM exposure.

Diesel emissions significantly influence composition and mutagenicity of ambient particles: a case study in São Paulo, Brazil

In 2003, a bus strike paralyzed the fleet of buses in Sao Paulo, Brazil during 3 days, from 6 to 8 of April, the complete interruption of services being achieved on the 7th. We evaluated the effect of the absence of this source of pollution on the composition, mutagenicity, and toxicity of the fine particulate material collected during this period. Particles were sampled in glass fiber filters on days 7 and 15 of April of 2003 (strike and nonstrike days, respectively), using a high-volume sampler. Trace element determinations (As, Br, Co, Cl, Fe, La, Mn, Sb, Sc, and Th) of particulate material samples were carried out by neutron activation analysis. Sulfur determination was done by X-ray fluorescence analysis. The ratio between nonstrike/strike concentrations of hydrocarbons associated with automotive emissions (benzene, toluene, ethyl-benzene, and xylenes; BTEX) was determined by gas chromatography/mass spectrometry. Mutagenesis of testing solutions was determined by means of the Tradescantia micronucleus assay in early tetrads of Tradescantia pallida. The inhibition of mitosis of the cells of the primary meristema of the root tips of Allium cepa was used as an index of the toxicity. Fine particle trace element contents were lower during the strike. The concentrations of sulfur and BTEX were 50% and 39.3% lower, respectively, on the strike day. A significant (P=0.038) reduction of micronuclei induced by fine particles sampled during the strike was observed. No effect of the strike on toxicity was detected. These results indicate that a program aiming to reduce emissions of the bus fleet in our town may impact positively the air quality by reducing the mutagenic potential of ambient particles.

The genotoxicity of ambient outdoor air, a review: Salmonella mutagenicity

Mutagens in urban air pollution come from anthropogenic sources (especially combustion sources) and are products of airborne chemical reactions. Bacterial mutation tests have been used for large, multi-site, and/or time series studies, for bioassay-directed fractionation studies, for identifying the presence of specific classes of mutagens, and for doing site- or source-comparisons for relative levels of airborne mutagens. Early research recognized that although carcinogenic PAHs were present in air samples they could not account for the majority of the mutagenic activity detected. The mutagenicity of airborne particulate organics is due to at least 500 identified compounds from varying chemical classes. Bioassay-directed fractionation studies for identifying toxicants are difficult to compare because they do not identify all of the mutagens present, and both the analytical and bioassay protocols vary from study to study. However, these studies show that the majority of mutagenicity is usually associated with moderately polar/highly polar classes of compounds that tend to contain nitroaromatic compounds, aromatic amines, and aromatic ketones. Smog chamber studies have shown that mutagenic aliphatic and aromatic nitrogen-containing compounds are produced in the atmosphere when organic compounds (even non-mutagenic compounds) are exposed to nitrogen oxides and sunlight. Reactions that occur in the atmosphere, therefore, can have a profound effect on the genotoxic burden of ambient air. This review illustrates that the mutagenesis protocol and tester strains should be selected based on the design and purpose of the study and that the correlation with animal cancer bioassay results depends upon chemical class. Future emphasis needs to be placed on volatile and semi-volatile genotoxicants, and on multi-national studies that identify, quantify, and apportion mutagenicity. Initial efforts at replacing the Salmonella assay for ambient air studies with some emerging technology should be initiated.

The effects of seasonal weather on the genotoxicity, cytokinetic properties, cytotoxicity and organochemical content of extracts of airborne particulates in Mexico City

Extracted organic material (EOM) from PM10 airborne particles collected during three distinct seasons in Mexico City was assayed for genotoxicity, cytokinetic effects and cytotoxicity. Using sister chromatid exchange (SCE) for genotoxicity, replication index (RI) and mitotic index (MI) for cytokinetics, and microscopic evaluation (cell death) for cytotoxicity on human lymphocytes exposed to increasing concentrations of EOM, this study showed that the extent of genotoxic, cytokinetic, and cytotoxic change caused by pollutants depended at least in part on the seasonal weather. Bioactivated extracts of samplings in April (warm and dry), August (warm and rainy) and November (cool and dry) produced the highest rate of genotoxicity (SCE) in November and the lowest rate in April. Without bioactivation the rates were still highest in November but equally low in April and August. Thus, almost all of the genotoxic responses in the bioactivation experiments during these latter months were from promutagens. However, in November equally large amounts of mutagens and promutagens were present. Cytokinetics (RI and MI) showed steady decreases as the concentration of EOM was increased, independent of bioactivation and weather. Cytotoxicity (cell death) occurred when higher concentrations of EOM were used. EOM was the least cytotoxic in April and most cytotoxic in November. Bioactivation was not required for cytokinetic change and cytotoxicity, suggesting that the agents involved may be different from the genotoxic agents. Using gas chromatography/mass spectroscopy (GC/MS) it could be shown that the type of pollutant chemicals in the EOM also depended on the weather. In particular, all 15 polycyclic aromatic hydrocarbons (PAH) studied were present in November EOM whereas four different PAH were absent in the other 2 months. Generally the amounts were less in the EOM collected in April and August. Conversely, nitro-PAH compounds were greater in number in April EOM but higher in amount in November EOM. The significance of these findings is discussed.

Mutagenic activity as a parameter to assess ambient air quality for protection of the environment and human health

Atmospheric pollution has significant effects on maintaining the integrity of ecosystems and on the population's quality of life. Epidemiological studies have clearly associated related health problems, especially respiratory diseases, with exposure to air pollution. Organic compounds adsorbed to the airborne particulate matter are mutagenic in the Salmonella/microsome assay, and a considerable number of them are known to be carcinogenic to rodents. Studies performed at four sites within the urban area of Porto Alegre, capital of the state of Rio Grande do Sul, identified higher mutagenic activity at the sites with heavier vehicle traffic in assays without and with metabolic activation. The responses varied at different seasons of the year, and the highest revertants per cubic meter (rev/m(3)) values were observed in spring for moderately polar compounds, and in summer for non-polar ones. A pilot study was also performed in the region under the influence of a industrial petrochemical area. Most of the sites studied within the industrial area, as compared to others sampled in the nearby environment, presented higher levels of mutagenic activity independent of total suspended particulates (TSP) concentration in the sample. In the urban and industrial regions, the observed mutagenic activities were strongly associated with the presence of polycyclic aromatic hydrocarbons (PAHs). The responses observed in the TA98NR and TA98/1,8-DNP(6) strains suggest the activity of nitrocompounds in both studies. The Salmonella/microsome assay is a sensitive method to define areas contaminated by these compounds, even in samples with TSP values that are consistent with the legal environmental quality standards.

Mutagenic activity of airborne particulate matter as an indicative measure of atmospheric pollution

Mutagenic activity of organic extracts of airborne particulate matter at four different sites within the urban area of the city of Porto Alegre, Brazil, was investigated using the Salmonella/microsome assay, with the Kado microsuspension method. The extracts were obtained by sonication, sequentially extracted according to polarity, with cyclohexane (CX) and dichloromethane (DCM) solvents. The different fractions were tested for mutagenicity with the Salmonella typhimurium strains TA98, TA98NR and TA98/1,8-DNP6, without S9 mix metabolic activation. A positive frameshift mutagenic response was observed for non-polar (CX) and/or moderately polar (DCM) compounds at the different sites. The responses varied at different seasons of the year, and the highest revertants per m3 (rev/m3) values were observed at the site subject to the strongest influence of automotive vehicles (site 3) in spring (17.13 rev/m3) in DCM fractions, and in summer (13.01 rev/m3) in CX fractions. The responses observed for the TA98NR and TA98/1,8-DNP6 strains suggest the contribution of nitrocompounds to the mutagenic activity observed. Although there appears to be an indicative association between the increased mass per unit volume of air (TSP) and the mutagenicity of organic extracts of airborne particulate matter in the present study, the Salmonella/microsome assay was a sensitive method to define areas contaminated by genotoxic compounds, even in samples that present TPS values acceptable by the environmental quality standards established by law.

Urban air pollution induces micronuclei in peripheral erythrocytes of mice in vivo

In this study, we explored the role of chronic exposure to urban air pollution in causing DNA damage (micronuclei frequency in peripheral erythrocytes) in rodents in vivo. Mice (n=20) were exposed to the urban atmosphere of São Paulo for 120 days (February to June 1999) and compared to animals (n=20) maintained in the countryside (Atibaia) for the same period. Daily levels of inhalable particles (PM10), CO, NO(2), and SO(2), were available for São Paulo. Occasional measurements of CO and O(3) were made in Atibaia, showing negligible levels of pollution in the area. The frequency of micronuclei (repeated-measures ANOVA) increased with aging, the highest values obtained for the 90th day of experiment (P<0.001). The exposure to urban air pollution elicited a significant (P=0.016) increase of micronuclei frequency, with no significant interaction with time of study. Associations (Spearman's correlation) between pollution levels of the week that precede blood sampling and micronuclei counts were observed in São Paulo. The associations between micronuclei counts and air pollution were particularly strong for pollutants associated with automotive emissions, such as CO (P=0.037), NO(2) (P<0.001), and PM10 (P<0.001). Our results support the concept that urban levels of air pollution may cause somatic mutations.

Biological activities of organic compounds adsorbed onto ambient air particles: comparison between the cities of Teplice and Prague during the summer and winter seasons 2000-2001

The capital of the Czech Republic, Prague, appears today to be one of the most polluted residential areas in the country, whereas air pollution in the Northern Bohemia region (the former "Black Triangle Region") has substantially decreased during the last decade, especially with respect to the gaseous pollutant SO(2). This study evaluated the biological activities of complex mixtures of organic compounds adsorbed onto ambient air particles (PM10) collected during the summer and winter seasons of 2000-2001 at three monitoring sites--Teplice (TP), Prague-Smíchov (PRG-SM) (city centre) and Prague-Libus (PRG-LB) (suburban area). The following short-term in vitro assays with strikingly different endpoints were used: a bacterial mutagenicity test using the Salmonella typhimurium tester strain TA98 and YG1041, an acellular assay (CT DNA) combined with 32P-postlabelling to evaluate DNA adduct-forming potency and the chick embryotoxicity screening test (CHEST). The results of the mutagenicity test with the YG1041 strain, the acellular genotoxicity (DNA adducts) and the embryotoxicity tests responded to the amount of eight carcinogenic polycyclic aromatic hydrocarbons (PAHs) analysed in the EOM (dichloromethane extractable organic matter) samples tested. Nevertheless, the biological effects of the EOM did not differ between locations. The highest biological activity of the ambient air in terms of organic compounds associated with particles (per unit volume of air) was seen in the Prague city centre during both summer and winter seasons. At this location, B[a]P concentration ranged from 0.1 to 8.9 ng/m(3) (mean 0.3 and 3.6 ng/m(3) for summer and winter seasons, respectively), 13 PAHs ranged from 11 to 343 ng/m(3) (mean 52 and 160 ng/m(3) for summer and winter seasons, respectively). Generally, using in vitro tests, higher ambient air activity was found in the winter season as compared with the summer season at all three monitoring sites (TA98 +S9, approximately 4-fold; YG1041 -S9, approximately 5-fold; YG1041 +S9, approximately 8-fold; CT DNA +S9, approximately 10-fold; CHEST, approximately 10-fold; B[a]P, carcinogenic PAHs and total PAHs analysed, more than 10-fold). The different proportions of individual PAHs found in the summer and winter samples suggested traffic as a major emission source in the summer and, additionally, residential heating in the winter season at all three monitoring sites. The DNA adduct patterns resulting from the in vitro acellular assay also demonstrated similar major emission sources at all three locations. The study shows that particle-bound carcinogenic-PAH concentrations may be taken as an index for the biologically active (mutagenic, genotoxic, embryotoxic) components in air particulate samples. Therefore, high-quality monitoring data of carcinogenic PAHs may be useful for epidemiological studies of the impact of air pollution on the health of the population and for helping decision makers to improve our environment.

Genotoxicity of fractionated organic material in airborne particles from São Paulo, Brazil

Particulate matter less than 10 microns aerodynamic diameter (PM10) is associated with adverse health effects including increased respiratory problems and mortality. PM10 is also associated with increases in cancer in some urban areas. Identification of toxic compounds in PM10 is a step toward estimating exposure to these compounds and evaluating their public health risk. However, the toxic compounds on PM10 are part of a highly complex mixture of compounds that makes chemical characterization difficult. Before this study, there has been little investigation of genotoxic compounds in particulate matter from Latin American cities. Here, both bioassay (mutagenicity) and chemical analyses were conducted with organic solvent extracts of PM10 collected from São Paulo, a major Brazilian city. Sequential extraction in dichloromethane (DCM) followed by acetone (ACE) yielded 20.3% and 10.2% of the total mass, respectively. Non-polar and moderately polar organic material solubilized in DCM. ACE extracted more polar organic species and some inorganic ions. Both extracts were fractionated separately using cyanopropyl-bonded silica chromatography with organic solvents of increasing polarity. The mass distribution among the fractions was measured. The mutagenic activity of the fractions was assayed using the microsuspension procedure with the Salmonella typhimurium tester strain TA98, with and without addition of metabolic enzymes (S9). The DCM extract had about four times higher mutagenic activity than the ACE extract. In general, addition of S9 resulted in an increase in mutagenicity of DCM fractions, but a decrease for the ACE extract. Most of the activity was concentrated in fractions in the mid-range of polarity within both the DCM and ACE extracts. The fractions were analyzed by gas chromatography with mass selective detection (GC/MS) without derivatization. The most mutagenic fractions in the DCM extract contained ketones, aldehydes, and quinolines. The most mutagenic ACE fraction had ketones, carboxylic acids, and aldehydes.

Genotoxicity of organic extracts of airborne particles in somatic cells of Drosophila melanogaster

Complex mixtures extracted from air filters exposed for 24 h in two sessions (27 July and 02 August 1991) and at two locations (Merced, downtown, and Pedregal de San Angel, south-west) in Mexico City were analysed. The organic extracts were from airborne particles equal or smaller than 10 microns (PM10), and from total suspended particles (TSP). These organic extracts were assayed in the somatic mutation and recombination test (SMART) in wings of Drosophila melanogaster using two different crosses as well as in the Salmonella/microsome assay using strain TA98 with and without S9 fraction. The presence of polycyclic aromatic hydrocarbons (PAH) in the extracts was determined by gas chromatography. The genotoxic activities observed in the two test systems were comparable with the indirect mutagens producing greater response than the direct mutagens. The quantities of particulate matter as well as the genotoxic activities were higher on 02 August than on 27 July 1991 for both locations. The amounts of airborne particles and the resulting genotoxic activities were higher at Merced than at Pedregal. In both biological systems, PM10 were more genotoxic than TSP. These results demonstrate the sensitivity of the Drosophila wing SMART-which is an in vivo eukaryotic genotoxicity assay-as a biological monitor of environmental pollution related to airborne particles.

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

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.