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.     

Mutagenicity and oxidative damage induced by an organic extract of the particulate emissions from a simulation of the deepwater horizon surface oil burns

Emissions from oil fires associated with the “Deepwater Horizon” explosion and oil discharge that began on April 20, 2010 in the Gulf of Mexico were analyzed chemically to only a limited extent at the time but were shown to induce oxidative damage in vitro and in mice. To extend this work, we burned oil floating on sea water and performed extensive chemical analyses of the emissions (Gullett et al., Marine Pollut Bull, in press, 2017 ). Here, we examine the ability of a dichloromethane extract of the particulate material with an aerodynamic size ≤ 2.5 µm (PM_2.5) from those emissions to induce oxidative damage in human lung cells in vitro and mutagenicity in 6 strains of Salmonella. The extract had a percentage of extractable organic material (EOM) of 7.0% and increased expression of the heme oxygenase (HMOX1) gene in BEAS‐2B cells after exposure for 4 hr at 20 µg of EOM/ml. However, the extract did not alter mitochondrial respiration rate as measured by extracellular flux analysis. The extract was most mutagenic in TA100 +S9, indicative of a role for polycyclic aromatic hydrocarbons (PAHs), reflective of the high concentrations of PAHs in the emissions (1 g/kg of oil consumed). The extract had a mutagenicity emission factor of 1.8 ± 0.1 × 10⁵ revertants/megajoule_thermal in TA98 +S9, which was greater than that of diesel exhaust and within an order of magnitude of open burning of wood and plastic. Thus, organics from PM_2.5 of burning oil can induce oxidative responses in human airway epithelial cells and are highly mutagenic. Environ. Mol. Mutagen. 58:162–171, 2017. © 2017 Wiley Periodicals, 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.     

Comparative mutagenicity of a coal combustion fly ash extract in Salmonella typhimurium and Chinese hamster ovary cells

The dichloromethane extract of a coal combustion fly ash sample obtained from an experimental fluidized bed coal combustor was tested for mutagenicity in Salmonella typhimurium and cultured Chinese hamster ovary (CHO) cells. The extract was directly mutagenic in S typhimurium strain TA98 and the nitroreductase deficient strains TA98NR and TA98/1,8DNP6. The mutagenicity observed in TA98NR and TA98/1,8DNP6 was lower than that in TA98. Addition of exogenous Aroclor 1254-induced rat liver supernatant (liver S9) decreased the bacterial mutagenicity of the extract. A different mutagenic response was observed in CHO cells. In the absence of liver S9, although the extract was cytotoxic to CHO cells, no significant mutagenicity was observed. Addition of exogenous liver S9 decreased the cytotoxicity and increased the mutagenicity at both Na+-K+-ATPase and hypoxanthine-guanine phosphoribosyl transferase (HGPRT) gene loci in CHO cells. Using gas chromatography/mass spectrometry (GC/MS) and tandem quadruple mass spectrometry, a number of polynuclear aromatic hydrocarbons (PAHs) and nitrated PAHs (nitro-PAHs) were tentatively identified and quantitated. A possible explanation of the difference in bacterial and mammalian mutagenicity of the extract is that the bacterial mutagenicity was induced by the nitro-PAHs that are potent bacterial mutagens and mammalian mutagenicity was induced by both PAHs and nitro-PAHs that are promutagens.     

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 m³ 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. Environ. Mol. Mutagen. 57:41–50, 2016. © 2015 Wiley Periodicals, Inc.     

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.     

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 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.     

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.     

Bioassay‐directed fractionation and sub‐fractionation for mutagenicity and chemical analysis of diesel exhaust particles

Several types of diesel exhaust particles (DEPs) have been used for toxicology studies, including a high‐organic automobile DEP (A‐DEP) from Japan, and a low‐organic forklift DEP developed by the National Institute of Standards and Technology (N‐DEP). However, these DEPs were not characterized extensively for chemical composition or sub‐fractionated and tested extensively for mutagenicity. We collected a compressor‐generated DEP (C‐DEP) and characterized it by conducting bioassay‐directed fractionation of the extractable organics in Salmonella and correlating the results by hierarchical clustering with the concentrations of 32 polycyclic aromatic hydrocarbons (PAHs). Relative to A‐ and N‐DEP, the mutagenic potency of C‐DEP was intermediate in TA100 +S9 (PAH mutagenicity) but was lowest in TA98 –S9 (nitroarene mutagenicity). More than 50% of the mass of the extractable organics of C‐DEP eluted in the nonpolar Fraction 1, and only ～20% eluted in the moderately polar Fractions 2 and 3. However, most of the mutagenicity eluted in Fractions 2 and 3, similar to A‐DEP but different from N‐DEP. HPLC‐derived mutagrams of 62 sub‐fractions per fraction confirmed that most of the mutagenicity was due to moderately polar compounds. The diagnostic strains identified a strong role for PAHs, nitroarenes, aromatic amines, and oxy‐PAHs in the mutagenicity of C‐DEP. Hierarchical clustering confirmed the importance of oxy‐PAHs but not that of nitroarenes. To our knowledge this is the first use of hierarchical clustering to correlate chemical composition with the mutagenicity of a complex mixture. The chemical analysis and mutagenicity of C‐DEP described here makes C‐DEP suitable for additional toxicological studies. Environ. Mol. Mutagen. 54:719–736, 2013. © 2013 Wiley Periodicals, Inc.     

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.     

Correlation between meteorological conditions and mutagenicity of airborne particupate samples in a tropical monsoon climate area from Kaohsiung City,Taiwan

Kaohsiung is a city of 1.5 million located in the southern part of Taiwan. It has a serious air pollution problem mainly attributable to much industrial and commercial activity. In order to estimate the effects of traffic, season, and meteorological conditions on the mutagenicity of Kaohsiung City's urban ambient particulate matter, 624 airborne particulate samples were collected on a weekly basis from 12 locations for an entire year. The mutagenic potential of acetone extracts of air samples was evaluated by the Salmonella/microsomal test with S. typhimurium TA98 in the presence and absence of S9 mixtures. The air samples from November 1990 showed the highest direct and indirect mutagenicity among the 12 months, whereas those from June and July 1991 had the lowest direct and indirect mutagenic activity, respectively. The mutagenicity showed a good correlation with amounts of the acetone extractable matter of airborne particulates. The meteorological conditions, monthly mean precipitation, and wind speed also showed a good correspondence with mutagenicity. Wind direction and temperature had a moderate relationship. The major mutagenic fractions of air samples that had the highest mutagenic activity in a month were purified using Sephadex LH-20 column chromatography, and the contents of PAHs, 1-NP, and DNPs were analyzed by HPLC. The characteristic concentration ratios of PAHs indicated that, for the main pollution sources of airborne particulates from Kaohsiung city, the mobile sources were more important than the stationary ones. The total amounts of 1-NP and DNPs in airborne particulates seemed to correspond to their mutagenicity. Although the total amounts of 1-NP and DNPs in the air samples correlated with their mutagenicity, the major mutagenic chemicals in the airborne particulate samples from Kaohsiung City need further investigation. © 1994 Wiley-Liss, Inc.     

Structure-mutagenicity relationships of benzidine analogues

The mutagenic activities of benzidine, its dihydrochloride salt, and 12 of their analogues were compared in the Ames test using strains TA100 and TA98 with and without rat liver S9 activation. With the exceptions of 4,4'-methylenebis(3-nitroaniline) in both strains and 3,3-dichlorobenzidine in TA98, little or no mutagenicity was observed in the series when tested without S9 activation. All compounds, except tetramethylbenzidine, exhibited some activity in TA100 with S9 activation; dichlorobenzidine and 4-aminobiphenyl were significantly more mutagenic than the other compounds. This was in contrast to the TA98 results where the bridged diphenyl compounds, with the exception of the nitroaniline derivative, were only slightly mutagenic compared to the more planar biphenyl series. Only the nitroaniline compound was mutagenic in both strains in the presence or absence of S9 activation. For benzidine and the 3,3'-disubstituted benzidines (the dimethoxy-, diamino-, and dichloro- compounds), an increase in mutagenicity correlated to a decrease in basicity of the parent anilines in both TA100 and TA98.     

Mutagenicity of carbon tetrachloride and chloroform in Salmonella typhimurium TA98, TA100, TA1535, and TA1537, and Escherichia coli WP2uvrA/pKM101 and WP2/pKM101, using a gas exposure method

The volatile solvents carbon tetrachloride and chloroform are carcinogens that are often reported as nonmutagenic in bacterial mutagenicity assays. In this study, we evaluated the mutagenicity of these compounds in Salmonella typhimurium TA98, TA100, TA1535, and TA1537, and Escherichia coli WP2uvrA/pKM101 and WP2/pKM101, with and without S9 mix, using a gas exposure method. Tests were also conducted with a glutathione-supplemented S9 mix. Carbon tetrachloride was mutagenic in TA98 without S9 mix, and in WP2/pKM101 and WP2uvrA/pKM101 with and without S9 mix; carbon tetrachloride was not mutagenic in TA100, TA1535 or TA1537. Chloroform was mutagenic in WP2/pKM101, but only in the presence of glutathione-supplemented S9 mix. Chloroform was not mutagenic in TA98, TA100, TA1535, TA1537, or WP2uvrA/pKM101 with or without S9 mix, and was not mutagenic in TA98, TA100, TA1535, TA1537, or WP2uvrA/pKM101 in the presence of glutathione-supplemented S9 mix. The data indicate that carbon tetrachloride and chloroform are bacterial mutagens when adequate exposure conditions are employed and suggest that a genotoxic mode of action could contribute to the carcinogenicity of these compounds.     

Evaluation of the mutagenicity of azo dyes in Salmonella typhimurium: a study of structure-activity relationships

In order to explore structure-activity relationships, 4,4'-diaminoazobenzene and four structurally related azo dyes were tested for their ability to induce gene mutations in Salmonella typhimurium strains TA1535, TA100, TA1537, TA1538, and TA98. Only 4,4'-diaminoazobenzene and 4,4'-N(beta-hydroxyethylamino)azobenzene were found to be active in the two frameshift strains TA1538 and TA98. Further tests were performed in strain TA98, both in the presence and in the absence of Aroclor 1254-induced rat or hamster liver S9 preparations. The amount of S9 used per plate was 50, 100, 150 or 300 microliters, which corresponds to 10, 20, 30 or 60% of S9 in S9 mix. 4,4'-Diaminoazobenzene was found to be mutagenic, and its mutagenicity depended on the percentage of S9 in S9 mix and the type of S9 fraction used. 4,4'-N-(beta-Hydroxyethylamino)azobenzene was less mutagenic than 4,4'-diaminoazobenzene, indicating a reduction in mutagenicity associated with the beta-hydroxyalkyl substituents. The other three azo dyes [4'-methyl-4-N,N-di(beta-hydroxyethylamino) azobenzene; 4'-amino-6-methyl-4-N,N-di(beta-hydroxyethylamino)azobenzene; and 4'-N(beta-hydroxyethyl-amino)4-N,N-di(beta-hydroxyethylamino)azobe nzene] were inactive, both in the presence and in the absence of the metabolic activation system. The use of the preincubation test did not alter the observed positive or negative response of these compounds. The importance of this finding is that the non-mutagenicity or decreased mutagenicity of these four compounds is predictable on the basis of their chemical structures. These azo dyes, like the non-mutagenic members of series of monocyclic aromatic amines, contain large substituents on one or both of the amino groups of the parent compound, in this case 4,4'-diaminoazobenzene. From our earlier data and the experiments discussed in this paper, we conclude that the study of structure--activity relationships can provide useful information for the prediction and interpretation of mutagenic responses.     

Mutagenic potentials of dental cements as detected by the Salmonella/microsome test

The potential mutagenicity of a zinc phosphate (Poscal), a polycarboxylate (Aqualox) and glass ionomer cements with (Argion) and without (Meron) silver reinforcement were characterized by employing the Ames Salmonella/microsome test. The materials were eluted in dimethyl sulphoxide or physiologic saline and the aliquots were used either immediately or after an incubation period of 24h at 37 degrees C. Mutagenic effects of the materials were tested on Salmonella typhimurium strains TA 98, TA 100, TA 102 and TA 1535 using the standard plate incorporation assay, and in the presence or absence of S9 fraction from rat liver. Poscal and Aqualox elicited mutagenic effects on S. typhimurium TA 98 and TA 1535, whereas Meron exhibited mutagenic effects on S. typhimurium TA 98. No mutagenic effects were detected for Argion. The type of solvent, dose of the material and incubation as well as the interactions between these factors exhibited varying degrees of influences on the mutagenic activities of the cements (P<0.05 and P<0.1). We conclude that zinc phosphate, polycarboxylate, and glass ionomer cements may have possible mutagenic activities.     

Salmonella/human S9 mutagenicity test: a collaborative study with 58 compounds

A large and extensive body of data on the use of human liver S9 fractions in the Salmonella mutagenicity test (Ames test) is presented; the data were obtained from a collaborative study by JEMS/BMS (Bacterial Mutagenicity Test Study Group) members and the Human and Animal Bridging Research Organization (HAB). In this study, the mutagenicity of 58 chemicals, many of which were judged to be human carcinogens by the IARC, was determined by the Ames test (the pre-incubation method at 37 degrees C for 20 min) in the presence of a selected human liver S9 fraction with a high drug-metabolic activity or a pooled human liver S9 fraction with a moderate drug-metabolic activity. For reference, mutagenicity was also examined in the presence of a phenobarbital/5,6-benzoflavone-pretreated rat liver S9 fraction, which is normally used in mutagenicity testing systems. The bacterial test strains consisted of Salmonella typhimurium TA100, TA98 or YG7108. The data indicated that the mutagenicity of chemicals in the rat and human liver S9 fractions varied considerably, depending on the chemicals in question. In addition, a large inter-individual diversity in the mutagenic response to mutagens, depending on the chemical structures of the mutagens, was also demonstrated using two selected human S9 fractions. Most of the mutagens tested in this study (75%; 36 out of 48 compounds that were judged to be mutagenic in at least one S9 fraction) were less mutagenic in the presence of the two human S9 fractions than in the presence of the rat S9 fraction. On the other hand, the other compounds (25%), including some aromatic amines and nitrosamines, showed a more potent mutagenicity in the presence of either one of the two human S9 fractions than in the presence of the rat S9 fraction. These data strongly suggest that the use of human liver S9 fraction in mutagenicity testing systems may be useful for a better understanding of the mutagenic effects of chemicals on humans.     

Mutagenic evaluation of trichlorfon using different assay methods with Salmonella typhimurium

Evaluation of the mutagenicity of trichlorfon pesticide was carried out with strains TA1535, TA100, TA97, TA98 and TA104 of Salmonella typhimurium by means of several assay methods: (i) spot test; (ii) standard plate incorporation test; (iii) plate incorporation test with preincubation; (iv) fluctuation test and (v) fluctuation test with preincubation, with and without post-mitochondrial liver fraction (S9) from Wistar rats pretreated with phenobarbital and 5,6-benzoflavone as a metabolic activation system. Trichlorfon induced base-pair substitution mutations, and its mutagenic activity was decreased by the addition of S9 mix. The fluctuation test and fluctuation test with preincubation were the most sensitive assay methods for detecting the mutagenicity of trichlorfon.     

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.     

Examination of Alternaria alternata mutagenicity and effects of nitrosylation using the Ames Salmonella test.

Molds of the genus Alternaria are common food pathogens responsible for the spoilage of fruits, vegetables, grains, and nuts. Although consumption of Alternaria alternata-contaminated foodstuffs has been implicated in an elevated incidence of esophageal carcinogenesis, the mutagenic potencies of several A. alternata toxins seem unable to account for the levels of activity found using crude mycelial extracts. In this study, the mutagenic effects of nitrosylation were examined with the major Alternaria metabolites Altenuene (ALT), Alternariol (AOH), Alternariol Monomethyl Ether (AME), Altertoxin I (ATX I), Tentoxin (TENT), Tenuazonic Acid (TA), and Radicinin (RAD) using the Ames Salmonella strains TA98 and TA100. In the absence of nitrosylation, ATX I was mutagenic when tested from 1 to 100 microg/plate in TA98 with rat liver S9 for activation, while AOH and ATX I were weakly mutagenic +/- S9 in TA100. Incubation with nitrite generally increased mutagenic potencies with ATX I strongly mutagenic +/- S9 in both TA98 and TA100, while ALT, AOH, AME, and RAD responses were enhanced in TA100 + S9. However, subsequent examination of three extracts made from A. alternata culture broth, acetone-washed mycelia, and the acetone washes showed a different mutagenic response with both broth and acetone washes directly mutagenic in TA98 and TA100 but with a reduced response + S9. The acetone-washed mycelial extract was found to have the lowest mutagenic activity of the three extracts tested. Nitrosylation had little effect on the mutagenicity of any of the extracts. Thus, while nitrosylation increases the mutagenicity of ATX I, and to a lesser extent that of several other Alternaria toxins, the results demonstrate that Alternaria produces a major mutagenic activity with a S. typhimurium response different from that found with the purified toxins. Efforts are currently underway to chemically identify this mutagenic species. Published 2001 Wiley-Liss, Inc.