Bioassay-directed chemical analysis of genotoxic components in urban airborne particulate matter from Barcelona (Spain)

Bioassay-directed analysis-based identification of relevant pyrrolizidine alkaloids

Pyrrolizidine alkaloids (PAs) are produced by various plant species and have been detected as contaminants in food and feed. Monitoring programmes should include PAs that are present in relevant matrices and that exhibit a high toxic potential. The aim of the present study was to use a bioassay-directed analysis approach to identify relevant PAs not yet included in monitoring programmes. To that end, extracts of Heliotropium europaeum and H. popovii were prepared and analysed with LC–MS/MS for the presence of 35 PAs included in monitoring programmes, as well as for genotoxic activity in the HepaRG/γH2AX assay. Europine, heliotrine and lasiocarpine were found to be the most abundant PAs. The extracts showed a higher γH2AX activity than related artificial mixtures of quantified known PAs, which might point to the presence of unknown toxic PAs. The H. europaeum extract was fractionated and γH2AX activities of individual fractions were determined. Fractions were further analysed applying LC–Orbitrap-MS analysis and Compound Discoverer software, identifying various candidate PAs responsible for the non-explained genotoxic activity. Altogether, the results obtained show that bioassay-directed analysis allows identification of candidate PAs that can be included in monitoring programmes.

Identification of persulfate oxidation products of polycyclic aromatic hydrocarbon during remediation of contaminated soil

The extent of PAH transformation, the formation and transformation of reaction byproducts during persulfate oxidation of polycyclic aromatic hydrocarbons (PAHs) in coking plant soil was investigated. Pre-oxidation analyses indicated that oxygen-containing PAHs (oxy-PAHs) existed in the soil. Oxy-PAHs including 1H-phenalen-1-one, 9H-fluoren-9-one, and 1,8-naphthalic anhydride were also produced during persulfate oxidation of PAHs. Concentration of 1,8-naphthalic anhydride at 4h in thermally activated (50°C) persulfate oxidation (TAPO) treatment increased 12.7 times relative to the oxidant-free control. Additionally, the oxy-PAHs originally present and those generated during oxidation can be oxidized by unactivated or thermally activated persulfate oxidation. For example, 9H-fluoren-9-one concentration decreased 99% at 4h in TAPO treatment relative to the control. Thermally activated persulfate resulted in greater oxy-PAHs removal than unactivated persulfate. Overall, both unactivated and thermally activated persulfate oxidation of PAH-contaminated soil reduced PAH mass, and oxidized most of the reaction byproducts. Consequently, this treatment process could limit environmental risk related to the parent compound and associated reaction byproducts.

Effects-directed analysis of sediments from polluted marine sites in Norway

The environmental status of two polluted marine sites in Norway was investigated by a combination of target chemical analysis and effect-directed analysis (EDA). The two selected sites, the Grenland area and Oslo harbor, in addition to two reference sites, were classified according to the Norwegian environmental classification system based upon results of the target chemical analyses. The polluted sites were characterized by high levels of metals, polycyclic aromatic hydrocarbons (PAH), and polychlorinated biphenyls (PCB). High levels of organotin compounds were also detected in Oslo harbor. The aryl hydrocarbon receptor (AhR) agonist activity in extracts of sediments from marine sites close to Oslo, Oslo harbor, and Grenland were investigated using the CALUX (chemical-activated luciferase expression) assay, which showed elevated levels of activity. As expected from the history of dioxin release into the Grenland area, the results were highest in this area. The presence of estrogen receptor (ER) and androgen receptor (AR) antagonists was also detected in the sediment extracts. Following fractionation of the sediment extracts, EDA was used to tentatively identify the AhR agonists. The compounds responsible for AhR agonist activity in samples from Oslo harbor were isolated in fraction 13, and to a lesser extent in fractions 9-11. In Grenland, the main activity was found in the more polar fractions, namely fractions 14-18. The AhR agonists identified in Oslo harbor were mainly PAH, while in the Grenland area the compounds identified were mainly nitrogen/oxygen-containing polyaromatic compounds (N/O-PAC).

Activated toxicity of diesel particulate extract by ultraviolet a radiation in mammalian cells: role of singlet oxygen

BACKGROUND

Diesel exhaust [diesel exhaust particles (DEPs) and their extracts (DPE)] and ultraviolet A radiation (UVA) are two ubiquitous environmental factors that have been identified as essential risk factors for various benign or malignant human diseases, either alone or in combination with other agents.

OBJECTIVES

We aimed to investigate the synergistic effects of DPE and UVA at low-dose exposures in human-hamster hybrid (AL) cells and their underlying mechanisms.

METHODS

We exposed exponentially growing AL cells to DPE and/or UVA radiation with or without reactive oxygen species (ROS) quenchers and then assayed the cells for survival, mutation induction, apoptosis, and micronucleus generation. In addition, using a singlet oxygen (1O2) trapping probe, 2,2,6,6-tetramethyl-4-piperidone, coupled with electron paramagnetic resonance spectroscopy, we determined the production of 1O2.

RESULTS

Treatment of AL cells with DPE+UVA induced significant cytotoxic and genotoxic damage. In contrast, we found no significant damage in cells treated with either UVA or DPE alone at the same doses. Mutation spectra of CD59- mutants showed that treatment with DPE+UVA easily induces multilocus deletions. Sodium azide significantly inhibited both cellular and DNA damage induced by DPE+UVA treatment, whereas other ROS inhibitors had little protecting effect. Furthermore, we found a significant increase of 1O2 in the cells that received DPE+UVA treatment.

CONCLUSION

These findings suggest that UVA activated the genotoxicity and cytotoxicity of DPE in mammalian cells and that 1O2 played an important role in these processes.

Aryl hydrocarbon receptor and estrogen receptor ligand activity of organic extracts from road dust and diesel exhaust particulates

A wide variety of contaminants derived from diesel and gasoline engines, tire, asphalt, and natural organic compounds is found in road dust. Polycyclic aromatic compounds (PACs) are the important toxic targets among various contents in road dust and diesel exhaust particulates (DEPs), and endocrine-disrupting activity of PACs was suggested. In the present study, aryl hydrocarbon receptor (AhR) ligand activity was confirmed in the extract of both road dust and DEPs. In the separation of the extracts for both road dust and DEPs with reversed-phase HPLC, it was found that polar fractions contributed to significant AhR ligand activity in both a mouse hepatoma (H1L1) cell system and a yeast system. Furthermore, the contribution of these polar fractions was higher in DEPs than in road dust, probably because of the greater concentration of oxy-PAHs in DEPs than in road dust. The contribution of contaminants associated with the polar region to AhR ligand activity was also evident following the separation of road dust with normal-phase HPLC. Additionally, remarkable estrogen receptor (ER) ligand activity was detected in the highly polar region separated with normal-phase HPLC. It is suggested that many unknown AhR or ER ligand active compounds are contained in the polar region.

Sources, fate, and toxic hazards of oxygenated polycyclic aromatic hydrocarbons (PAHs) at PAH-contaminated sites

In this paper we show that oxygenated polycyclic aromatic hydrocarbons (oxy-PAHs) are important cocontaminants that should be taken into account during risk assessment and remediation of sites with high levels of PAHs. The presented data, which have been collected both from our own research and the published literature, demonstrate that oxy-PAHs are abundant but neglected contaminants at these sites. The oxy-PAHs show relatively high persistency and because they are formed through transformation of PAHs, their concentrations in the environment may even increase as the sites are remediated by methods that promote PAH degradation. Furthermore, we show that oxy-PAHs are toxic to both humans and the environment, although the toxicity seems to be manifested through other effects than those known to be important for polycyclic aromatic compounds in general, that is, mutagenicity and carcinogenicity. Finally, we present data that support the hypothesis that oxy-PAHs are more mobile in the environment than PAHs, due to their polarity, and thus have a higher tendency to spread from contaminated sites via surface water and groundwater. We believe that oxy-PAHs should be included in monitoring programs at PAH-contaminated sites, even if a number of other toxicologically relevant compounds that may also be present, such as nitro-PAHs and azaarenes, are not monitored. This is because oxy-PAH levels are difficult to predict from the PAH levels, because their environmental behavior differs substantially from that of PAHs, and oxy-PAHs may be formed as PAHs are degraded.

Biodirected mutagenic chemical assay of PM(10) extractable organic matter in Southwest Mexico City

The concentration of breathable particles (PM(10)) in urban areas has been associated with increases in morbidity and mortality of the exposed populations, therein the importance of this study. Organic compounds adsorbed to PM(10) are related to the increased risk to human health. Although some studies have shown the lack of correlation between specific mutagenic compounds in an organic complex mixture (OCM) and the mutagenic response in several bioassays, the same organic compounds selectively separated in less complex groups can show higher or lower mutagenic responses than in the OCM. In this study, we fractionated the OCM, from the PM(10) in four organic fractions of increasing polarity (F1-F4). The Salmonella bioassay with plate incorporation was applied for each one using TA98, with and without S9 (mammalian metabolic activation), and YG1021 (without S9) strains. The most polar fraction (F4) contained the greatest mass followed by F1 (non-polar), F2 and F3 (moderately polar). The concentrations of the OCM as well as the F4 were the only variables correlated with PM(10), atmospheric thermal inversions, fire-prone area, NO(2), SO(2), CO, rain and relative humidity. This indicated that polar organic compounds were originated in gas precursors formed during the atmospheric thermal inversions as well as the product of the incomplete combustion of vehicular exhausts and of burned vegetation. The percentages of the total PAH, and the individual PAH with molecular weight > or = 228 g mol(-1) (except retene) correlated with the percentages of indirect-acting mutagenicity in TA98+S9. The percentages of the total nitro-PAH and most of the analyzed individual nitro-PAH correlated with percentages of the direct-acting mutagenicity in both TA98-S9 and YG1021, the latter being more sensitive. In general, the highest mutagenic activity (indirect and direct) was found in F3 (moderately polar) and in F4 (polar). The non-polar fraction (F1) did not exhibit any kind of mutagenicity. In 77% of the cases, mutagenic activity was higher in the sum fractions with respect to their OCM. The combinations between F1, F2 and F4, with F3 under different or equal proportions suggested that mutagenicity reduction, in the combined matter of January (with TA98+S9 and YG1021) and of May (with YG1021), was due to concentrations of mutagens and non-mutagens in each fraction, and not to an antimutagenic effect. The organic compounds present in the non-polar fractions showed no antagonism, inhibition or reduction in the most mutagenic fractions in both indirect- and direct-acting mutagenicity, and the less polar organic compounds in F3 reduced mutagenicity in F4, in both months.

Aryl hydrocarbon receptor plays a significant role in mediating airborne particulate-induced carcinogenesis in mice

Urban particulate air pollution is associated with an increased incidence of cancers, and especially lung cancer. Organic extracts of airborne particulate matter (APM) cause cancer in mice, and PAHs adsorbed to APM are associated with particle-induced carcinogenesis. PAHs are agonists for AhR and are predominantly responsible for lung cancer through induction of highly carcinogenic metabolites. PAH metabolization requires CYP1A1 induction through activation of AhR, and therefore we hypothesized that carcinogenesis due to PAHs in APM would be reduced in AhR-/- mice. To examine this hypothesis, we performed a long-term continuous-application study of carcinogenesis in AhR-/- mice using airborne particulate extract (APE) of APM collected in Sapporo. Tumor development (squamous cell carcinoma) occurred in 8 of 17 AhR+/+ mice (47%), but no tumors were found in AhR-/-mice, and CYP1A1 was induced in AhR+/+ mice but not in AhR-/- mice. These results demonstrate that AhR plays a significant role in APE-induced carcinogenesis in AhR+/+ mice and CYP1A1 activation of carcinogenic PAHs is also of importance. Therefore, measurement of CYP1A1 induction in vitro may be useful for assessment of APM-induced carcinogenesis in humans. We also show that PAH-like compounds are major contributors to AhR-mediated carcinogenesis, whereas TCDD and related compounds make a smaller contribution.

Development of analytical methods for polycyclic aromatic hydrocarbons (PAHs) in airborne particulates: a review

In the present work, the different sample collection, pretreatment and analytical methods for polycyclic aromatic hydrocarbons (PAHs) in airborne particulates is systematacially reviewed, and the applications of these pretreatment and analytical methods for PAHs are compared in detail. Some comments on the future expectation are also presented.

Characterization and classification of complex PAH samples using GC-qMS and GC-TOFMS

The aim of this study was to compare the polycyclic aromatic hydrocarbon (PAH) contents in a number of complex samples, including soil samples from industrial sites, anti-skid sand, urban dust and ash samples from municipal solid waste incinerators. The samples were characterized by routine analysis of PAHs (gas chromatography-quadrupole mass spectrometry) and gas chromatography-time of flight mass spectrometry (GC-TOFMS). Classification of the samples by principal component analysis (PCA) according to their composition of PAHs revealed that samples associated with traffic and the municipal incinerator formed homogeneous clusters, while the PAH-contaminated soils clustered in separate groups. Using spectral data to resolve co-eluting chromatographic peaks, 962 peaks could be identified in the GC-TOFMS analysis of a pooled sample and 123-527 peaks in the individual samples. Many of the studied extracts included a unique set of chemicals, indicating that they had a much more diverse contamination profile than their PAH contents suggested. Compared to routine analysis, GC-TOFMS provided more detailed information about each sample and in this study a large number of alkylated PAHs were found to be associated with the corresponding unsubstituted PAHs. The possibility to filter peaks according to different criteria (e.g. to include only peaks that were detected in the analysis of another sample) was explored and used to identify unique as well as common compounds within samples. This procedure could prove to be valuable for obtaining relevant chemical data for use in conjunction with results from various biological test systems.

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.

Development of an analytical method for polycyclic aromatic hydrocarbons and their derivatives

The possibilities of utilising pressurised liquid extraction for five nitro-polycyclic aromatic hydrocarbons from an inert matrix are shown. Different extraction temperatures and pressures were tested. The highest recoveries were obtained at extraction pressure 14 MPa and temperature 100 C. Separation of non-polar, aromatic and polar fractions by the silica gel column chromatography is shown. n-Hexane, cyclohexane and dichloromethane as a solvent were tested. The best separations of monitored fractions were obtained, when extract was dissolved in cyclohexane. Non-polar and aromatic fractions eluted together when the extract was dissolved in dichloromethane.

Human-cell mutagens in respirable airborne particles in the northeastern United States. 1. Mutagenicity of fractionated samples

Few studies have characterized the regional scale (300-500 km) variability of the mutagenicity of respirable airborne particles (PM2.5). We previously collected 24-h PM2.5 samples for 1 year from background, suburban, and urban sites in Massachusetts (MA) and rural and urban sites in upstate New York (NY) (n = 53-60 samples per site). Bimonthly composites of these samples were mutagenic to human cells. The present report describes our effort to identify chemical classes responsible for the mutagenicity of the samples, to quantify spatial differences in mutagenicity, and to compare the mutagenicity of samples composited in different ways. Organic extracts and HPLC fractions (two nonpolar, one semipolar, and one polar) of annual composites were tested for mutagenicity in the h1A1v2 cells, a line of human B-lymphoblastoid cells that express cytochrome P450 CYP1A1 cDNA. The mutagenic potency (induced mutant fraction per microg organic carbon) of the semipolarfractions was the highest at all five sites, accounting for 35-82% of total mutagenic potency of the samples, vs the nonpolar (4-38%) and polar (14-32%) fractions. These results are consistent with previous studies. While unfractionated extracts exhibited no spatial variations, the mutagenicity of semipolar fractions at the NY sites was approximately 2-fold higher than at the MA sites. This suggests there may be significant regional differences in the sources and/ or transport and transformation of mutagenic compounds in PM2.5. In addition, mutagenic potency was sensitive to whether samples were fractionated and how they were composited: unfractionated annual composite samples at the NY sites were significantly less mutagenic than their semipolar fractions and the annual average of bimonthly composites; spatial differences in the mutagenic potency of bimonthly composites and the semipolar fractions were not apparent in the annual composites.

Linking exposure to environmental pollutants with biological effects

Exposure to ambient air pollution has been associated with cancer. Ambient air contains a complex mixture of toxics, including particulate matter (PM) and benzene. Carcinogenic effects of PM may relate both to the content of PAH and to oxidative DNA damage generated by transition metals, benzene, metabolism and inflammation. By means of personal monitoring and biomarkers of internal dose, biologically effective dose and susceptibility, it should be possible to characterize individual exposure and identify air pollution sources with relevant biological effects. In a series of studies, individual exposure to PM(2.5), nitrogen dioxide (NO(2)) and benzene has been measured in groups of 40-50 subjects. Measured biomarkers included 1-hydroxypyrene, benzene metabolites (phenylmercapturic acid (PMA) and trans-trans-muconic acid (ttMA)), 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) in urine, DNA strand breaks, base oxidation, 8-oxodG and PAH bulky adducts in lymphocytes, markers of oxidative stress in plasma and genotypes of glutathione transferases (GSTs) and NADPH:quinone reductase (NQO1). With respect to benzene, the main result indicates that DNA base oxidation is correlated with PMA excretion. With respect to exposure to PM, biomarkers of oxidative damage showed significant positive association with the individual exposure. Thus, 8-oxodG in lymphocyte DNA and markers of oxidative damage to lipids and protein in plasma associated with PM(2.5) exposure. Several types of DNA damage showed seasonal variation. PAH adduct levels, DNA strand breaks and 8-oxodG in lymphocytes increased significantly in the summer period, requiring control of confounders. Similar seasonal effects on strand breaks and expression of the relevant DNA repair genes ERCC1 and OGG1 have been reported. In the present setting, biological effects of air pollutants appear mainly related to oxidative stress via personal exposure and not to urban background levels. Future developments include personal time-resolved monitors for exposure to ultrafine PM and PM(2.5,) use of GPS, as well as genomics and proteomics based biomarkers.

Development of a sequential supercritical fluid extraction method for the analysis of nitrated and oxygenated derivatives of polycyclic aromatic hydrocarbons in urban aerosols

A two-step supercritical fluid extraction (SFE) method has been developed for the analysis of oxygenated and nitrated polycyclic aromatic hydrocarbons (oxy- and nitro-PAHs, respectively) present in urban aerosol samples. The proposed SFE procedure first involves an extraction step using pure CO2 in order to remove the less polar compounds from the matrix and a second consecutive step using toluene-modified CO2. The oxy- and nitro-PAHs are obtained in the second step. Parameters affecting both collection efficiencies and the selective extraction of oxy- and nitro-PAHs in the second SFE step were optimised. Analysis of the extracts was performed using gas chromatography with electron-capture detection and coupled to mass spectrometry. The proposed SFE method was compared with a conventional extraction technique such as sonication and good agreement in the results was obtained. Nevertheless, clean up of sonication extracts was needed, whereas no purification was necessary for SFE extracts. The SFE method was applied to the analysis of oxy- and nitro-PAHs in urban aerosol samples and 9-fluorenone, 9,10-anthraquinone, 2-methyl-9,10-anthraquinone, benzanthrone, benz[a]anthracene-7,12-dione and 1-nitropyrene were identified at concentrations ranging between 15 and 364 pg m(-3).

Isolation and taxonomic and catabolic characterization of a 3,6-dimethylphenanthrene-utilizing strain of Sphingomonas sp

A bacterial strain capable of utilizing 3,6-dimethylphenanthrene (3,6-DMP) as its sole source of carbon and energy was isolated from a creosote-contaminated soil. The isolate was identified as a strain of Sphingomonas sp. and was designated strain JS1. Utilization of 3,6-DMP was demonstrated by an increase in bacterial biomass concomitant with a decrease in 3,6-DMP in a liquid mineral medium with this compound as its sole source of carbon and energy. Strain JS1 showed a high specificity in the use of the most abundant alkylderivatives of crude oils, such as alkylnaphthalenes and other alkylphenanthrenes, as the sole source of carbon and energy. It can also use several polycyclic aromatic hydrocarbons of three and four rings and their alkylated derivatives as growth substrates or transform them. The identification of several intermediate metabolites points to extensive metabolic activity, including the following: (i) aromatic ring oxidation and cleavage, (ii) methyl group oxidations, and (iii) methylenic oxidations. The metabolic actions of Sphingomonas sp. JS1 on the aromatic fraction extracted from a creosote-contaminated soil are also examined.

Bioassay-directed chemical analysis of River Elbe surface water including large volume extractions and high performance fractionation

A bioassay-directed fractionation and identification (toxicity identification evaluation procedure) was performed on extracts of 10 1 River Elbe water samples. The experimental method included a SDB-1 solid phase extraction followed by RP-HPLC fractionation and subfractionation. Chemical analysis by GC-MS as well as acute toxicity testing using a luminescent bacteria assay were conducted in the respective fractions. Many substances were identified, among which were pesticides and pharmaceuticals, but many compounds remained unknown.

Quantitative analysis of polycyclic aromatic hydrocarbons in sewage sludge from wastewater treatment plants

Polycyclic aromatic hydrocarbons (PAHs) are an important group of organic contaminants present in sewage sludge. Due to their persistence and toxic potential, information about their presence in sewage sludge is needed in order to assess applicability on agricultural land. A method for the gas chromatographic-mass spectrometric (GC-MS) determination was developed and applied to the trace determination of PAHs present in sewage sludge samples from six wastewater treatment plants (WWTPs) differing in the type of treatment and the origin of wastewater. PAHs were extracted from freeze-dried samples by a dichloromethane-methanol (2:1) mixture in a sonication bath. The sludge extracts were cleaned-up by an alumina column. The method showed recovery values varying from 60 to 98%. Four surrogate standards ([2H8]naphthalene, [2H10]anthracene, [2H12]benzo[a]anthracene, and [2H12]benzo[ghi]perylene) were used for quantitation by GC-MS. A reference sludge sample was analysed in order to validate the method. The sum of the 16 US Environmental Protection Agency PAHs analysed in the sewage sludge samples varied from 1.13 to 5.52 mg/kg. No significant difference between the different WWTPs was found.

Urban airborne particulate: genotoxicity evaluation of different size fractions by mutagenesis tests on microorganisms and comet assay

The genotoxic effects of different size fractions of airborne particulate (Total, PM10 and PM25), extracted with acetone or toluene, were evaluated by: the Ames plate test (TA98 and TA100 strains, w/o S9), gene conversion and reversion (w/o endogenous metabolic activation) in the Saccharomyces cerevisiae D7 strain, and the comet assay on human leukocytes. The data on human leukocytes confirm the sensitivity of the comet assay and its applicability to assess genotoxicity in environmental samples. The PM2.5 fraction of airborne particulate generally shows the highest concentration of DNA-damaging compounds. Genotoxic response, in all the test systems applied, is highly dependent on extraction solvent used. Acetone seems to extract compounds with more similar genotoxic responses in the three test systems used than toluene extracts. Toluene appears to extract air pollutants genotoxic on yeast and leukocytes but is mainly cytotoxic on Salmonella.

Photolysis of PAHs in aqueous phase by UV irradiation

The photooxidation of polycyclic aromatic hydrocarbons (PAHs) was investigated in an aqueous ethanolic solution irradiated with a medium-pressure mercury lamp in laboratory photoreactors equipped with a quartz immersion well. Degradation photolysis of fluorene was more efficient than sensitized photolytic oxidation in the presence of TiO2 suspensions. Photolysis kinetics was dependent on molecular weight and the presence and type of substituents. During the photolytic degradation of fluorene and its derivatives, 9-fluorenone and its corresponding derivatives, which were more resistant to photolysis, were formed.

The influence of automobile exhausts on mutagenicity of soils: contamination with, fractionation, separation, and preliminary identification of mutagens in the Salmonella/reversion assay and effects of solvent fractions on the sister-chromatid exchanges in human lymphocyte cultures and in the in vivo mouse bone marrow micronucleus assay

To test the assumption that automobile exhausts contribute to soil mutagenicity, two soils with low levels of mutagenic activities were exposed to traffic exhausts at a heavily charged junction of German motorways (Autobahnen) for 3, 7, 10, 13, 17, 21, and 26 weeks. Indeed, in the presence of a metabolic activation system from rat liver (S9), an average increase of 8 and 9 (4 and 12) revertants per gram per week was found in Salmonella typhimurium TA 98 (TA 100). In the absence of S9, meaningful measurements were impossible on account of a concurrent dose dependent increase of toxicity. No correlation between the increase of mutagenicity and the contents of polycyclic aromatic hydrocarbons (PAH) could be detected. In another series, soils sampled at the roadside and at distances of 10 and 50m of five roads near Mainz expressed 10-20-fold higher mutagenicity (revertants per gram) under identical test conditions as compared with the average of agricultural soils. Toxic effects, however, again confounded the results and no correlation between the distance from roads and the levels of mutagenicity could be demonstrated. Subsequently, Soxhlet-extraction with the solvent sequence dichloromethane, acetone, and toluene/diethylketone was found to be an optimum procedure for soils at roadsides. The mass balance of solvent fractionation of such soils revealed that <2% each belonged to organic acids and bases, approximately 4% to fractions designed polar neutrals, approximately 8% to polar aromatics, approximately 7% to dichloromethane solubles, and approximately 79% to cylohexane solubles, among them approximately 63% acetone soluble compounds. The major part of mutagenicity (55-65%) was present in the fraction of polar aromatics, followed by polar neutrals and the acetone subfraction of cyclohexane solubles ( approximately 10% each) summarizing the results obtained with S. typhimurium TA 98, TA 98NR, YG 1021, YG 1024, TA 100, YG 1026, and YG 1029 with and without addition of S9. The modified tester strains, either deficient in nitroreductase (TA 98NR) or overproducing nitroreductase (YG 1021, 1026) or O-acetyl-transferase (YG 1024, 1026), indicated a major contribution of nitroarenes to soil mutagenicity. With respect to mutagenic PAH, high pressure liquid chromatography (HPLC) revealed that >90% of dibenz[a,h]anthracene (4.18mg/kg soil), benzo[a]pyrene (1.96mg), benzofluoranthenes (0.14mg), and benz[a]anthracene (0. 18mg) were present in the acetone subfraction of cyclohexane solubles. Concentrations and mutagenic activities, however, did not correlate. Additional preparative and analytical HPLC of the solvent fractions of polar neutrals and polar aromatics, resulted in the tentative identification of 2-nitrofluorene. Analysis of the vertical profile of soil revealed an increase of mutagenicity per gram from the surface to a maximum at 5-15cm depth and a subsequent decrease with very little activity remaining deeper than 35cm. In human lymphocyte cultures, the fraction of polar aromatics, 0.01-0. 3microg/ml, induced 11.27+/-4.76-20.70+/-6.19 sister-chromatid exchanges (SCE) per cell in the absence of S9 (solvent control: 10. 16+/-4.83 SCE per cell) and 12.77+/-6.53-17.87+/-4.93 SCE per cell in the presence of S9 (solvent control: 8.37+/-3.92 SCE per cell). However, no activities could be detected in the fractions of polar neutrals and non-polar neutrals. Again, negative results were obtained in the in vivo mouse bone marrow micronucleus assay at 2000mg/kg p.o. with all fractions.

Chemicals in Diesel Exhaust Particles Generate Reactive Oxygen Radicals and Induce Apoptosis in Macrophages

There is increasing evidence that particulate air pollutants, such as diesel exhaust particles (DEP), potentiate chronic inflammatory processes as well as acute symptomatic responses in the respiratory tract. The mechanisms of action as well as the cellular targets for DEP remain to be elucidated. We show in this paper that the phagocytosis of DEP by primary alveolar macrophages or macrophage cell lines, RAW 264.7 and THP-1, leads to the induction of apoptosis through generation of reactive oxygen radicals (ROR). This oxidative stress initiates two caspase cascades and a series of cellular events, including loss of surface membrane asymmetry and DNA damage. The apoptotic effect on macrophages is cell specific, because DEP did not induce similar effects in nonphagocytic cells. DEP that had their organic constituents extracted were no longer able to induce apoptosis or generate ROR. The organic extracts were, however, able to induce apoptosis. DEP chemicals also induced the activation of stress-activated protein kinases, which play a role in cellular apoptotic pathways. The injurious effects of native particles or DEP extracts on macrophages could be reversed by the antioxidant, N-acetyl-cysteine. Taken together, these data suggest that organic compounds contained in DEP may exert acute toxic effects via the generation of ROR in macrophages.

Genotoxicity and embryotoxicity of urban air particulate matter collected during winter and summer period in two different districts of the Czech Republic

This study is the in vitro part of a long-term program to investigate the impact of air pollution on the health of a population in a polluted region of Northern Bohemia. In order to assess the possible health risks associated with a complex mixture of hundreds of organic compounds adsorbed to air particles, we used a biomarker-directed fractionation procedure to evaluate biological activities of different chemical compound classes. The extractable organic compounds from the air particles collected in both the polluted and the control districts during the summers and winters of 1993-1994 were investigated. The principal aim of this study was to compare the DNA binding activities of those compound classes using an in vitro acellular assay coupled with 32P-postlabeling and an embryotoxicity assay using Chick Embryotoxicity Screening Test (CHEST). In both assays, the highest activity was due to the neutral fractions from which the aromatic subfractions containing mainly polycyclic aromatic hydrocarbons (PAHs) and their methyl-derivates were the most active for both localities and seasons. A good correlation between the levels of DNA adduct formation using S9 metabolic activation and the ED50 for all different complex mixtures of organic compounds was observed (r=0.773, p<0.001). DNA adduct maps and high performance liquid chromatography (HPLC) profiles were similar for samples from both districts and seasons. The major DNA adducts resulting from the crude extracts were identical to those derived from aromatic fractions. The DNA adducts tentatively identified constituted about 50% of the total adducts formed by the crude extracts following S9-metabolic activation. Our results confirmed the similarities of the major ubiquitous emission sources of organic compounds in both districts. This is the first report in which the biological activities of complex mixtures in short-term assays with remarkably different endpoints such as DNA adduct formation and embryotoxicity have been compared.

Genotoxicity of coke-oven and urban air particulate matter in in vitro acellular assays coupled with 32P-postlabeling and HPLC analysis of DNA adducts

This study is an in vitro part of the ongoing biomarker studies with population from a polluted region of Northern Bohemia and coke-oven workers from Czech and Slovak Republics. The aim of this study is to compare DNA adduct forming ability of chemical compound classes from both the urban and coke-oven extractable organic mass (EOM) of airborne particles. The crude extracts were fractionated into seven fractions by acid-base partitioning and silica gel column chromatography. In in vitro acellular assays we used calf thymus DNA (CT DNA) with oxidative (+S9) and reductive activation mediated by xanthine oxidase (+XO) under anaerobic conditions. Both the butanol and nuclease P1 versions of 32P-postlabeling for detection of bulky aromatic and/or hydrophobic adducts were used. The results showed that the spectra of major DNA adducts resulting from both the in vitro assays are within the fractions similar for both the urban and coke-oven samples. The highest DNA adduct levels with S9-activation were detected for the neutral aromatic fraction, followed by slightly polar and acidic fractions for both samples. With XO-mediated metabolism, the highest DNA adduct levels were detected for both the acidic fractions. Assuming additivity of compound activities, then the acidic fraction, which in the urban sample comprises a major portion of EOM mass (28%), may contain the greatest activity in both in vitro assays (39 and 69%, +S9 and +XO, respectively). In contrast, the aromatic fraction constituting only 8% of total urban EOM mass may account for comparable activity (34%) with organic acids. The highest DNA adduct forming activity of the coke-oven sample accounts for the aromatic fraction (82 and 63%, +S9 and +XO, respectively) that also contains the greatest portion of the total EOM (48%). To characterize some of the specific DNA adducts formed, we coupled TLC on 20x20 cm plates with HPLC analysis of 32P-postlabeled adducts. In both S9-treated samples of the aromatic fraction, we tentatively identified DNA adducts presumably diolepoxide-derived from: 9-hydroxy-benzo[a]pyrene (9-OH-B[a]P), benzo[a]pyrene-r-7,t-8-dihydrodiol-t-9,10-epoxide[+/-] (anti-BPDE), benzo[b,j,k]fluoranthenes (B[b]F, B[j]F, B[k]F), chrysene (CHRY), benz[a]-anthracene (B[a]A) and indeno[cd]pyrene (I[cd]P). These DNA adducts accounted for about 57% of total DNA adducts detected in both S9-treated samples of the aromatic fraction. DNA adducts of XO-treated samples were sensitive to nuclease P1 and HPLC profiles of the major adducts were markedly different from the major adducts of S9-treated samples. However, the combination of TLC and HPLC did not confirm the presence of DNA adducts derived from 1-nitropyrene (1 NP), 9-nitroanthracene (9 NA) and 3-nitrofluoranthene (3 NF) that were detected by GC-MS in the slightly polar fraction. We concluded that the chemical fractionation procedure facilitates the assessing of DNA adduct forming ability of different chemical compound classes. However, based on the results obtained with the whole extracts, it does not fulfil a task of the actual contribution of individual fractions within the activity of the whole extracts. Our results are the first in detecting of DNA adducts derived from urban air and coke-oven particulate matter.

New metabolites in the degradation of fluorene by Arthrobacter sp. strain F101

Identification of new metabolites and demonstration of key enzyme activities support and extend the pathways previously reported for fluorene metabolism by Arthrobacter sp. strain F101. Washed-cell suspensions of strain F101 with fluorene accumulated 9-fluorenone, 4-hydroxy-9-fluorenone, 3-hydroxy-1-indanone, 1-indanone, 2-indanone, 3-(2-hydroxyphenyl) propionate, and a compound tentatively identified as a formyl indanone. Incubations with 2-indanone produced 3-isochromanone. The growth yield with fluorene as a sole source of carbon and energy corresponded to an assimilation of about 34% of fluorene carbon. About 7.4% was transformed into 9-fluorenol, 9-fluorenone, and 4-hydroxy-9-fluorenone. Crude extracts from fluorene-induced cells showed 3,4-dihydrocoumarin hydrolase and catechol 2,3-dioxygenase activities. These results and biodegradation experiments with the identified metabolites indicate that metabolism of fluorene by Arthrobacter sp. strain F101 proceeds through three independent pathways. Two productive routes are initiated by dioxygenation at positions 1,2 and 3,4, respectively. meta cleavage followed by an aldolase reaction and loss of C-1 yield the detected indanones. Subsequent biological Baeyer-Villiger reactions produce the aromatic lactones 3,4-dihydrocoumarin and 3-isochromanone. Enzymatic hydrolysis of the former gives 3-(2-hydroxyphenyl) propionate, which could be a substrate for a beta oxidation cycle, to give salicylate. Further oxidation of the latter via catechol and 2-hydroxymuconic semialdehyde connects with the central metabolism, allowing the utilization of all fluorene carbons. Identification of 4-hydroxy-9-fluorenone is consistent with an alternative pathway initiated by monooxygenation at C-9 to give 9-fluorenol and then 9-fluorenone. Although dioxygenation at 3,4 positions of the ketone apparently occurs, this reaction fails to furnish a subsequent productive oxidation of this compound.