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 m³/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 m³/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. Environ. Mol. Mutagen. 55:510–517, 2014. © 2014 Wiley Periodicals, Inc.     

Mutagenicity of blue rayon extracts of fish bile as a biomarker in a field study

Blue rayon (BR) in combination with the Salmonella/microsome assay was used to evaluate the mutagenicity of fish bile samples. Specimens of Mugil curema from two sites were collected over a 1‐year period. Piaçaguera channel contains high concentrations of total polycyclic aromatic hydrocarbons (PAHs) and other contaminants, while Bertioga channel was considered the reference sites in this study. Bile was extracted with BR and tested with TA98, TA100, and YG1041 strains with and without S9 in dose response experiments. PAH metabolite equivalents were analyzed using reverse‐phase high performance liquid chromatography /fluorescence. Higher mutagenic responses were observed for the contaminated site; YG1041 with S9 was the most sensitive strain/condition. Mutagenicity ranged from 3,900 to 14,000 rev./mg at the contaminated site and from 1,200 to 2,500 rev./mg of BR at the reference site. The responses of YG1041 were much higher in comparison with the TA98 indicating the presence of polycyclic compounds from the aromatic amine class that cause frameshift mutation. TA100 showed a positive mutagenic response that was enhanced following S9 treatment at both sites suggesting the presence of polycyclic compounds that require metabolic activation. benzo(a)pyrene, naphthalene, and phenanthrene metabolite equivalents were also higher in the bile of fish collected at the contaminated site. It was not possible to correlate the PAH metabolite quantities with the mutagenic potency. Thus, a combination of the Salmonella/microsome assay with YG1041 with S9 from BR bile extract seems to be an acceptable biomarker for monitoring the exposure of fish to mutagenic polycyclic compounds. Environ. Mol. Mutagen., 2010. © 2009 Wiley‐Liss, 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.     

A promising Ames battery for mutagenicity characterization of new dyes

When testing new products, potential new products, or their impurities for genotoxicity in the Ames test, the quantity available for testing can be a limiting factor. This is the case for a dye repository of around 98,000 substances the Max Weaver Dye Library (MWDL). Mutagenicity data on dyes in the literature, although vast, in several cases is not reliable, compromising the performance of the in silico models. In this report, we propose a strategy for the generation of high‐quality mutagenicity data for dyes using a minimum amount of sample. We evaluated 15 dyes from different chemical classes selected from 150 representative dyes of the MWDL. The purity and molecular confirmation of each dye were determined, and the microplate agar protocol (MPA) was used. Dyes were tested at the limit of solubility in single and concentration‐response experiments using seven strains without and with metabolic activation except for anthraquinone dyes which were tested with eight strains. Six dyes were mutagenic. The most sensitive was YG1041, followed by TA97a > TA98 > TA100 = TA1538 > TA102. YG7108 as well as TA1537 did not detect any mutagenic response. We concluded that the MPA was successful in identifying the mutagenicity of dyes using less than 12.5 mg of sample. We propose that dyes should be tested in a tiered approach using YG1041 followed by TA97a, TA98, and TA100 in concentration‐response experiments. This work provides additional information on the dye mutagenicity database available in the literature.     

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.     

1-nitropyrene as a marker for the mutagenicity of diesel exhaust-derived particulate matter in workplace atmospheres

The use of 1-nitropyrene (1-NP) as a marker for the occupational exposure to diesel exhaust (DE) mutagens was investigated in workplace atmospheres contaminated with DE from a variety of emission sources, such as power supplies, forklifts, trucks, caterpillar vehicles, trains, ships' engines, and vehicles in city traffic. Total suspended particulate matter was collected by area sampling. The 1-NP content of acetone extracts of these samples as determined by gas chromatography-high resolution mass spectrometry varied from 0.080 to 17 μg/g acetone extractable matter, corresponding to air concentrations of 0.012 to 1.2 ng/m³. A sample collected in a rural area contained 0.0017 ng/m³ 1-NP. The mutagenicity of the extracts was tested in the Salmonella typhimurium strains TA98 and TA1538, using the microsuspension assay with and without metabolic activation by an exogeneous metabolizing system (rat liver S9-fraction). In addition, the S. typhimurium strains YG1021 and YG1024 were used because of their high sensitivity towards the mutagenicity of nitro polycyclic aromatic hydrocarbons. When plotting the mutagenic potency of the air sample extracts as determined in the absence of liver S9 versus the particle-associated 1-NP level, a relatively high correlation (r = 0.80–0.91) was observed in all of the S. typhimurium strains. High correlations (r = 0.80–0.93) were also observed when plotting the results of mutagenicity testing after activation by S9 versus the outcome of chemical analysis. These results show that the 1-NP content of workplace air samples is associated with their mutagenic potency, suggesting that 1-NP may be used as a marker for occupational exposure to DE-de-rived particle-associated mutagens © 1995 Wiley-Liss, Inc.     

Combining different assays and chemical analysis to characterize the genotoxicity of waters impacted by textile discharges

Waters receiving textile discharges can exhibit genotoxic and mutagenic activity, which has been related to the presence of dyes and aromatic amines as synthesis precursors or byproducts. The aim of this study was to identify dyes and aromatic amines in water samples impacted by textile discharges, and to evaluate the genotoxic responses of these samples using the Salmonella/microsome assay in strains TA98 and YG1041, and the Fpg‐modified comet assay in the RTL‐W1 fish cell line. The genotoxicity of river samples downstream of the discharge was greater than the upstream samples in both of the Ames tests. The Fpg‐modified comet assay detected similar levels of DNA damage in the upstream and downstream samples. Mutagenicity was not detected with TA98, except for the Quilombo River samples, but when YG1041 was used as the tester strain mutagenicity was detected for all sites with a very different profile in upstream sites relative to the other sites. The mutagenic response strongly indicated that aromatic amines or dyes were contributing to the mutagenic activity downstream. The impact of textile discharges was also confirmed by chemical analysis, because the highest concentrations of azo dyes and aromatic amines were detected in the river downstream. This study shows the value of combining assays measuring complementary endpoints to better characterize the mutagenicity of environmental samples, with the advantage that this approach provides an indication of what classes of compounds are responsible for the effect. Environ. Mol. Mutagen. 57:559–571, 2016. © 2016 Wiley Periodicals, Inc.     

Mutagenicity of an aged gasworks soil during bioslurry treatment

This study investigated changes in the mutagenic activity of organic fractions from soil contaminated with polycyclic aromatic hydrocarbons (PAHs) during pilot‐scale bioslurry remediation. Slurry samples were previously analyzed for changes in PAH and polycyclic aromatic compound content, and this study examined the correspondence between the chemical and toxicological metrics. Nonpolar neutral and semipolar aromatic fractions of samples obtained on days 0, 3, 7, 24, and 29 of treatment were assayed for mutagenicity using the Salmonella mutation assay. Most samples elicited a significant positive response on Salmonella strains TA98, YG1041, and YG1042 with and without S9 metabolic activation; however, TA100 failed to detect mutagenicity in any sample. Changes in the mutagenic activity of the fractions across treatment time and metabolic activation conditions suggests a pattern of formation and transformation of mutagenic compounds that may include a wide range of PAH derivatives such as aromatic amines, oxygenated PAHs, and S‐heterocyclic compounds. The prior chemical analyses documented the formation of oxygenated PAHs during the treatment (e.g., 4‐oxapyrene‐5‐one), and the mutagenicity analyses showed high corresponding activity in the semipolar fraction with and without metabolic activation. However, it could not be verified that these specific compounds were the underlying cause of the observed changes in mutagenic activity. The results highlight the need for concurrent chemical and toxicological profiling of contaminated sites undergoing remediation to ensure elimination of priority contaminants as well as a reduction in toxicological hazard. Moreover, the results imply that remediation efficacy and utility be evaluated using both chemical and toxicological metrics. Environ. Mol. Mutagen. 2009. © 2009 Wiley‐Liss, Inc.     

Physical‐chemical and microbiological characterization,and mutagenic activity of airborne PM sampled in a biomass‐fueled electrical production facility

Biomass combustion is used in heating and electric power generation in many areas of the world. Airborne particulate matter (PM) is released when biomass is brought to a facility, stored, and combusted. Occupational exposure to airborne PM within biomass‐fueled facilities may lead to health problems. In March and August of 2006, airborne PM was collected from a biomass‐fueled facility located in Denmark. In addition, source‐specific PM was generated from straw and wood pellets using a rotating drum. The PM was analyzed for polycyclic aromatic hydrocarbons (PAHs), metals, microbial components, mutagenic activity, and ability to generate highly reactive oxygen species (hROS) in cell‐free aqueous suspensions. PM collected from the boiler room and the biomass storage hall had higher levels of mutagenic activity, PAHs and metals, and a higher hROS generating potential than the source specific PM. The mutagenic activity was generally more potent without S9 activation, and on the metabolically enhanced strain YG1041, relative to TA98. Significant correlations were found between mutagenicity on YG1041 (without S9) and PAH concentration and mutagenicity on YG1041 (with S9) and hROS generating ability. PM collected in March was more toxic than PM collected in August. Overall, airborne PM collected from the facility, especially that from the boiler room, were more toxic than PM generated from straw and wood chips. The results suggest that exposure to combustion PM in a biomass‐fueled facility, which likely includes PM from biomass combustion as well as internal combustion vehicles, may contribute to an elevated risk of adverse health effects. Environ. Mol. Mutagen., 2011. © 2010 Wiley‐Liss, Inc.     

Mutagenicity and chemical analysis of airborne particulates from a rural area in italy

Mutagenic activities of a sample of characterized airborne particulates collected in a rural location near Ispra (Italy) during the summer of 1980 were detected by the Ames test using TA 1537, TA 1538, TA 98, and TA 100 Salmonella strains. Eight chemical classes fractionated from the CH₂Cl₂ extract of the particulates were bioassayed, and their mutagenicities (TA 98 plus S9) were as follows: organic bases I > polar neutrals > insolubles in cyclohexane > organic acid II > aerosol “in toto” > intermediate neutrals > polycyclic aromatic hydrocarbons > organic acids I > nonpolar neutrals. Periodical samples were taken in the same location from March to December 1981, extracted in dimethyl sulfoxide (DMSO), and directly tested with TA 1537, TA 98, and TA 100 Salmonella strains. For all the strains the mutagenicity varied markedly according to the season, the cold-month samples being much more mutagenic than the summer-month samples. The additional of S9 increased the mutagenicity (twofold) of the cold-month samples. The higher mutagenicity of the samples collected during the cold months could be due to greater amounts of mutagens produced by the combustion processes of domestic heating.     

Mutagenicity of some benzidine congeners and their N-acetylated and N,N′-diacetylated derivatives in different strains of Salmonella typhimurium

The Ames Salmonella/microsome test was used to compare the mutagenic response of Salmonella typhimurium TA100, TA98, TA1538, and TA1535 to 12 benzidine derivatives, ie, benzidine, 3,3′-dimethoxybenzidine, 3,3′-dimethylbenzidine, 3,3′-dichlorobenzidine, and the corresponding N- and W,W-diacetylated derivatives. With a few exceptions, the mutagenic response to this series of compounds varied in the order TA98 > TA1538 > TA100 > TA1535 = 0, and the N-monoacetylated derivatives were more mutagenic than either the parent diamines or the N,N′-diacetyl derivatives. The relative mutagenicities of the parent amines for TA98 were 3,3′-dichlorobenzidine > > 3,3′-dimethoxybenzidine > benzidine > 3,3′-dimethylbenzidine.     

Structure-mutagenicity relationships of four amino-imidazonaphthyridines and imidazoquinolines

We tested four isomeric imidazonaphthyridines and one imidazoquinoline compound for mutagenic activity in the Ames/Salmonella mutagenicity assay, using strain TA98 and strain YG1024, an analogue of strain TA98 with elevated O-acetyl-transferase levels. Their potency was related to calculated electronic parameters. Five compounds with a linear arrangement of 3 rings showed a positive response in strain YG1024. Compound 2 (1-methyl-imidazo[4,5-b][1,7]naphthyridin-2-amine) is the most mutagenic in both strains, giving specific activities of about 200 and 30 revertants per microgram in strains YG1024 and TA98, respectively. Three of the compounds were weak mutagens, giving a positive dose-response only in strain YG1024, with 3–5 revertants per microgram. A higher response of all five compounds in strain YG1024 as opposed to TA98 indicates that they require O-acetyltransferase activity for their metabolism. Mutagenic potencies in strain YG1024 were positively correlated to the energy of the LUMO (lowest unoccupied molecular orbital) of the nitrenium ion. © 1995 Wiley-Liss, Inc.     

SOS induction in Escherichia coli and Salmonella mutagenicity: a comparison using 330 compounds

To examine the concordance of two microbial genotoxicity short-termassays, 330 experimental results for the SOS chromotest usingtester strain Escherichia coli PQ37 were compared with the resultsof the Salmonella/mammalian microsome mutagenicity assay withSalmonella typhimurium TA97, TA98, TA100, TA102, TA104, TA1535,TA1537 and/or TA1538. With respect to qualitative features,the concordance between SOS chromotest and Salmonella mutagenicitytest results was 86.4% (sensitivity, 78.6%; specificity, 100%;     

Reduction in the mutagenicity of synthetic dyes by successive treatment with activated sludge and the ligninolytic fungus, Irpex lacteus

Synthetic dyes are released in wastewater from textile manufacturing plants, and many of these dyes are genotoxic. In the present study, the mutagenicity of azo, anthraquinone, and triphenyl methane dyes was investigated before and after successive biodegradation with activated sludge and the ligninolytic fungus, Irpex lacteus. Two biodegradation systems were used to reduce the genotoxicity of dyes that were not efficiently inactivated by activated sludge alone. Mutagenicity was monitored with the Salmonella reversion assay conducted with the base-pair substitution detector strains, TA100 and YG1042, and the frame-shift detector strains, TA98 and YG1041, with and without rat liver S9. All dyes except for Congo Red (CR) were mutagenic with S9 activation. Assays conducted with the dyes indicated that only the azo dye Reactive Orange 16 (RO16) was mutagenic in both TA98 and TA100. Methyl Red and Disperse Blue 3 (DB3) were mutagenic in TA98, YG1041 and YG1042, while Reactive Black 5 was mutagenic in YG1041 and YG1042. Remazol Brilliant Blue R (RBBR), Crystal violet (CV) and Bromophenol Blue (BPB) were mutagenic only in TA98, but the toxicity of the latter two dyes complicated the evaluation of their mutagenicity. CR was not mutagenic in any of the tester strains. Biodegradation studies conducted with RO16 and DB3 indicated that the two-step biodegradation process reduced the mutagenic potential of RO16 and DB3 to a greater extent than activated sludge alone; the mutagenicity of the two dyes was reduced by 95.2% and 77.8%, respectively, by the two-step process. These data indicate that the combined biodegradation process may be useful for reducing the mutagenicity associated with wastewater from textile factories that contain recalcitrant dyes.     

Mutagenicity of the organic fraction of World Trade Center dust

Most studies of the health effects and chemical characterization of the dust resulting from the catastrophic collapse of the World Trade Center (WTC) on September 11, 2001, have focused on the large inorganic fraction of the dust; however, chemical analyses have identified mutagens and carcinogens in the smaller organic fraction. Here, we determined the mutagenicity of the organic fraction of WTC dust in Salmonella. Only 0.74% of the mass of the particulate matter (PM) <53 μm in diameter was extractable organic matter (EOM). Because the EOM was 10 times more mutagenic in TA100 +S9 than in TA98 +S9 and was negative in TA98 −S9, we inferred, respectively, that polycyclic aromatic hydrocarbons (PAHs) played a role in the mutagenicity and not nitroarenes. In TA98 +S9, the mutagenic potency of the EOM (0.1 revertant/μg EOM) was within the range of EOMs from air and combustion emissions. However, the EOM-based mutagenic potency of the particles (0.0007 revertants/μg PM) was 1–2 orders of magnitude lower than values from a review of 50 combustion emissions and various air samples. We calculated that 37 PAHs analyzed previously in WTC EOM were 5.4% of the EOM mass and 0.04% of the PM mass; some air contained 0.3 μg WTC EOM/m³ (0.02 μg PAHs/m³). Populations exposed to WTC dust have elevated levels of prostate and thyroid cancer but not lung cancer. Our data support earlier estimates that PAH-associated cancer risk among this population, for example, PAH-associated lung cancer, was unlikely to be significantly elevated relative to background PAH exposures.     

Evaluation of the genotoxicity of river sediments from industrialized and unaffected areas using a battery of short-term bioassays

The present investigation evaluated the capacity of the Salmonella mutagenicity test, the comet assay, and the micronucleus assay to detect and characterize the genotoxic profile of river sediments. Three stations were selected on an urban river (Bouches du Rhône, France) exposed to various sources of industrial and urban pollution (StA, StB, and StC) and one station on its tributary (StD). One station in a nonurban river was included (REF). The concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) were determined by HPLC, and the genotoxicity of the sediments was monitored by the Salmonella mutagenicity test (TA98 + S9, YG1041 ± S9), the comet assay, and the micronucleus assay on CHO cells. Chemical analysis showed that the total PAH concentrations ranged from 23 μg kg^?1 dw (REF) to 1285 μg kg^?1 dw (StD). All the sediments were mutagenic in the Salmonella mutagenicity test. The mutagenicity was probably induced by the presence of nitroarenes (StA, StB, StC, and StD) and aromatic amines (REF) as deduced from the mutagenicity profiles of strains YG1041 ± S9 and TA98 + S9. The comet assay revealed direct DNA lesions in REF, StA, and StB sediments and metabolization‐dependent DNA damage in StC and StD. The micronucleus assay showed an absence of clastogenicity for StA ± S9 and StC‐S9, and a significant clastogenicity ± S9 for the three other stations. The genotoxicity ranking determined by the comet assay + S9 matched the ranking of total and carcinogenic PAH concentrations, and this assay was found to be the most sensitive. Environ. Mol. Mutagen., 2008. © 2008 Wiley‐Liss, Inc.     

Mutagens in urban air particulate.

Extracts of airborne particulate matter were demonstrated to be mutagenic in the Salmonella/microsome test. Urban airborne particulate was collected with high-volume samplers in an Italian town mainly polluted by traffic exhaust fumes. After being weighted for determination of total dust, the particulate was extracted with CH2Cl2/methanol and assayed by Salmonella/microsome assay on strains TA98, TA100 and TA98NR. All samples were mutagenic on strain TA98, with a mutagenic potency of 50 +/- 14 (-S9), 128 +/- 63 (+S9) and 104 +/- 51 (-S9), 211 +/- 97 (+S9) revertants/mg of particulate for summer (n = 23) and winter (n = 22) determinations, respectively. The mutagenic activity on strain TA98NR was about one-half that on strain TA98, indicating a large contribution of nitroaromatic mutagenic compounds. Mutagens from airborne particulate were less active on strain TA100. The summer and winter mean values of urban total dust were 0.15 +/- 0.07 and 0.35 +/- 0.18 mg/m3 respectively, and the mutagenicity of urban air on strain TA98 was 8 +/- 5 (-S9), 22 +/- 17 (+S9) and 30 +/- 11 (-S9), 61 +/- 21 (+S9) revertants/m3 in the two seasons, respectively. In winter, besides an increase in urban air mutagenicity, there also was a change in direct particulate activity per milligram, which was double that of summer.     

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. Environ. Mol. Mutagen. 2008. © 2008 Wiley‐Liss, Inc.     

Characterization of mutagenic activity in instant hot beverage powders

Extracts of several grain-based coffee-substitute blends and instant coffees were mutagenic in the Ames/Salmonella test using TA98, YG1024, and YG1029 with metabolic activation. The beverage powders induced 150 to 500 TA98 and 1,150 to 4,050 YG1024 revertant colonies/g, respectively. Increased sensitivity was achieved using strain YG1024. No mutagenic activity was found in instant hot cocoa products. The mutagenic activity in the beverage powders was shown to be stable to heat and the products varied in resistance to acid nitrite treatment. Differential bacterial strain specificity, and a requirement for metabolic activation suggest that aromatic amines are present. Characterization of the mutagenic activity, using HPLC and the Ames test of the collected fractions, showed the coffee-substitute blends and instant coffees contain several mutagenic compounds. Known heterocyclic amines are not responsible for the major part of the mutagenic activity. The main mutagenic activity in grain-based coffee-substitute blends and instant coffees is due to several unidentified compounds, which are most likely aromatic amines. © 1995 Wiley-Liss, Inc.     

Identification of mutagens in freshwater sediments by the Ames-fluctuation assay using nitroreductase and acetyltransferase overproducing test strains

Extracts of sediments from an area of concern in the Elbe river basins (Spittelwasser creek) were analyzed with the Ames-fluctuation test and in parallel with gas chromatography/mass spectrometry for compound identification. The standard test strains TA 98 and TA 100 showed mutagenicity mainly in medium-polar fractions of the sediment extracts. PAHs contribute to the overall mutagenic potential of the sample. Especially, cyclopenta[c,d]pyrene that was previously not defined as a priority hazardous substance has to be considered as well. The addition of metabolically competent test strains, which overexpress nitroreductase and acetyltransferase (e.g., YG1041 and YG1042) to the test battery, increased significantly the sensitivity of the Ames test for medium polar to polar genotoxins. The increased mutagenicity that was found in these bacterial strains indicates the presence of nitroarenes and/or aromatic amines. In fact, a number of heterocyclic and nitrogen-substituted aromatic compounds were identified in the sediments of the Spittelwasser creek of which methyl parathion, 1-naphthylamine, and N-phenyl-2-naphthylamine are mutagenic.