delta 1-Tetrahydrocannabinol and 1 alpha, 2 alpha-epoxyhexahydrocannabinol: mutagenicity investigation in the Ames test.

1,2-Epoxyhexahydrocannabinol is a metabolite of delta 1-tetrahydrocannabinol. Because many epoxides are mutagens, we investigated 1,2-epoxyhexahydrocannabinol as well as delta 1-tetrahydrocannabinol for mutagenicity with Salmonella typhimurium TA1535, TA1537, TA98 and TA100 in the presence and in the absence of S9 mix from liver homogenate of rats treated with Aroclor 1254. Additionally, an epoxide hydratase inhibitor was used in some experiments. Whereas several other epoxides and further positive controls, not requiring activation or activated under the same conditions, respectively, showed strong mutagenicity, no indications of a mutagenic hazard by 1,2-epoxyhexahydrocannabinol or by delta 1-tetrahydrocannabinol were found.     

Studies on the mutagenicity of p-phenylenediamine in Salmonella typhimurium. Presence of PCB's in rat-liver microsomal fraction induced by Aroclor.

The mutagenicity of fresh solutions of p-phenylenediamine (PPD) and Aroclor 1254 was investigated. The histidine-requiring strains of Salmonella typhimurium were used in the absence and presence of uninduced and/or Aroclor-induced rat-liver homogenate. The presence of polychlorinated biphenyls (PCBs) was also examined by chromatographic methods in Aroclor-induced rat-liver homogenate. In the absence of metabolic activation, as well as in the presence of uninduced rat-liver homogenate, PPD was not mutagenic in the strains used. In the presence of Aroclor-induced S9 a twofold increase (or less) was observed in the number of revertant colonies over those of the controls in TA1538 and TA98. There was no increase in the number of revertant colonies over those of the controls when PPD was dissolved in NH4OH solution and the solution mixed with H2O2 before the addition of S9 mix. Aroclor 1254 was not mutagenic in TA1538 or TA98. However, the presence of PCBs in Aroclor-induced rat-liver homogenate (induced S9) was identified by gas-liquid chromatography (GLC), high-performance liquid chromatography (HPLC) and gas--liquid chromatography/mass spectrometry (GC/MS).     

Bacterial mutagenicity of some methyl 2-cyanoacrylates and methyl 2-cyano-3-phenylacrylates

The mutagenic potential of three alkyl 2-cyanoacrylate adhesives, three commercial alkyl 2-cyanoacrylate adhesives and three methyl 2-cyano-3-phenylacrylates, was assessed using the Salmonella/microsome mutagenicity assay. Compounds were tested with and without Aroclor 1254-induced rat-liver homogenate (S9 mix). The methyl 2-cyanoacrylate adhesives were mutagenic in the standard plate test with S. typhimurium strain TA100 with and without S9 activation. Methyl 2-cyano-3-(2-bromophenyl)acrylate revealed a direct mutagenic action to S. typhimurium strain TA1535. The compounds most toxic towards the bacterium S. typhimurium, were the methyl 2-cyanoacrylate adhesives (greater than 500 micrograms/plate). All alkyl 2-cyanoacrylate adhesives were tested in a modified spot test for volatile compounds with tester strain TA100. Mutagenic and toxic effects were observed with the three methyl 2-cyanoacrylate adhesives. It can be concluded from the results that the bacterial toxicity and mutagenicity of methyl 2-cyanoacrylate adhesives may be due to the methyl 2-cyanoacrylate monomer.     

Mutagenicity of 43 structurally related heterocyclic compounds and its relationship to their carcinogenicity.

43 heteropolycyclic compounds belonging to a homologous series were investigated for mutagenicity. The results are compared with carcinogenicity data obtained with the same batches of compounds under conditions identical for all of them. Mutagenicity was tested in the Ames test with Salmonella typhimurium strains TA1535, TA1537 and TA100 in the presence and absence of liver 10 000 g supernatant from rats treated with Aroclor 1254. Carcinogenicity was tested by injection of the compounds into subcutaneous tissue of XVIInc/Z mice. 18 test compounds showed carcinogenic activity, some strongly, others only weakly. Of these, 17 were detected as mutagens: one weak carcinogen did not revert the Salmonella strains. No quantitative correlation was observed between the extents of the mutagenic and the carcinogenic effects. Of the 25 substances that did not produce tumours, 13 showed mutagenicity (12 in the presence, 2 in the absence, of the liver homogenate). The mutagenic effects of these compounds were quantitatively similar to those of the compounds that produced tumours. The most sensitive strain of Salmonella typhimurium was TA100. It detected all 30 mutagens. TA98 was mutated by 25 compounds, TA1537 by 16 compounds. No mutagenic effects were seen with TA1535. Possible reasons for the high percentage of apparently "false positives" in the Ames test and the lack of a quantitative correlation between the potency of the mutagenic and carcinogenic effects are discussed. It is suggested that the complexity of the metabolism of these heterocyclic compounds may lead to critical differences in metabolism in mouse subcutaneous tissue in vivo and in liver homogenates from rats treated with Aroclor. Therefore the present study will be extended to life-long oral and intrahepatic carcinogenicity tests leading to a higher proportion of metabolism in the liver.     

Biphenyl and fluorinated derivatives: liver enzyme-mediated mutagenicity detected in Salmonella typhimurium and Chinese hamster V79 cells.

Hepatocarcinogenic polychlorinated and polybrominated biphenyls usually show negative results in in vitro mutagenicity assays. Problems in their testing result from their low water solubility and their slow rate of metabolism. We therefore investigated better soluble model compounds, namely biphenyl and its 3 possible monofluorinated derivatives. In the direct test, these compounds proved to be nonmutagenic in Salmonella typhimurium TA98 and TA100 (reversion to histidine prototrophy) and in Chinese hamster V79 cells (acquisition of resistance to 6-thioguanine). However, when the exposure was carried out in the presence of NADPH-fortified postmitochondrial fraction of liver homogenate from Aroclor 1254-treated rats, all 4 compounds showed mutagenic activity in V79 cells. 3-Fluorobiphenyl produced strong mutagenic effects in S. typhimurium TA100 as well, whereas the other biphenyls were inactive. In strain TA98, 3- and 4-fluorobiphenyl showed mutagenic activity. This mutagenicity was enhanced in the presence of 1,1,1-trichloropropene 2,3-oxide, an inhibitor of microsomal epoxide hydrolase, thus suggesting that epoxides may be active metabolites.     

Investigation of the mutagenic activity of tobacco smoke

The genotoxic effect of whole tobacco smoke was studied employing the Salmonella/microsome mutagenicity assay, the micronucleus test in mouse bone marrow and UDS in peripheral human lymphocytes. It was established that tobacco smoke (120-480 cm3 in a 16-1 glass chamber, at 1-10 min exposure time) induced a 3-9-fold increase of spontaneous his+ reversion mutation rate in S. typhimurium TA98, but not in strains TA97a, TA100 and TA102. Addition of S9 mix obtained from the liver of Aroclor 1254-treated rats was necessary to reveal the mutagenic activity of tobacco smoke. Treatment of BDF1 mice placed in a 14-1 glass chamber with tobacco smoke (600 cm3 smoke, 2 exposures of 30 min each, with a 1-min interval between them) caused a 2-fold dose-dependent elevation of the number of micronucleated PCE in bone marrow. No cumulative effect was detected when mice were treated with tobacco smoke during 2-28 consecutive days. The effect observed 24 h after tobacco-smoke exposure was abolished 48 h later. Tobacco smoke (180 or 360 cm3) passed through the culture medium (with or without S9 mix) of human peripheral lymphocytes (the cells were then incubated for 60 min at 37 degrees C) did not increase the spontaneous rate of UDS. Both the Salmonella/microsome mutagenicity assay employing S. typhimurium TA98 strain and the micronucleus test in mouse bone marrow might be useful in studying tobacco smoke-induced mutagenesis.     

Detection of 1-nitropyrene in yakitori (grilled chicken)

Pieces of raw chicken with or without a marinating sauce were grilled over a city gas flame, extracted with benzene-ethanol (4:1) by ultrasonication and fractionated into diethyl ether-soluble neutral, acidic and basic fractions. The mutagenicity of these fractions was measured with Salmonella typhimurium strains TA100, TA98, TA98NR and TA98/1,8-DNP6 in the presence and absence of a 9000 X g post-mitochondrial supernatant from Aroclor 1254-treated Sprague-Dawley rat liver (S9 mix). The basic fraction of yakitori without the sauce was more mutagenic than the other fractions for S. typhimurium strain TA98 in the presence of S9 mix. This is probably due to the presence of amino acid or protein pyrolysates. However, when the chicken was grilled with the sauce, the basic fraction showed lower mutagenicity for strain TA98 in the presence of S9 mix than did the same fraction without the sauce. The neutral fraction of yakitori with sauce showed high mutagenicity for strain TA98 in the absence of S9 mix, but low mutagenicity for strains TA98NR and TA98/1,8-DNP6, suggesting that this fraction might contain nitropyrenes (NPs). The neutral fraction of yakitori was analyzed by high-performance liquid chromatography (HPLC). The neutral fraction of the chicken grilled with the sauce for 3, 5 and 7 min contained 3.8, 19 and 43 ng, respectively, of 1-NP per gram of yakitori accounting for 3.0, 2.7 and 1.3%, respectively, of the total mutagenicity.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of the hepatic S9 fraction from aroclor-1254-treated rats on the mutagenicity of benzo[alpha]pyrene and 2-aminoanthracene in the Salmonella/microsome assay.

The mutagenicity of benzo[alpha]pyrene and 2-aminoanthracene for Salmonella typhimurium TA98 in the plate-incorporation test was studied using liver S9 from untreated and aroclor-1254-treated rats. The induction of liver S9 protein, arylhydrocarbon hydroxylase (AHH), and cytochrome P448/450 was followed with time. There was no change in protein concentrations with induction; AHH and cytochrome levels were increased at 1, 3, 5 and 7 days post Aroclor treatment. Benzo[alpha]pyrene mutagenicity was enhanced with Aroclor treatment while 2-aminoanthracene mutagenicity was depressed. The benzo[alpha]pyrene mutagenicity showed a positive correlation with the levels of AHH and cytochrome on the plate; 2-aminoanthracene showed a negative correlation with activity in induced samples.     

Genetic effects of isoniazid and the relationship to in vivo and in vitro biotransformation

The mutagenic activity of isoniazid, N-acetyl-isoniazid and hydrazine dihydrochloride was investigated in S. typhimurium. Isoniazid was found to possess a weak mutagenic activity only in repair-deficient strains TA1535 and TA100 as well as in the plasmid-containing strain TA92 (10-30 mg/plate) in the Ames test without metabolic activation. Addition of microsomal enzymes by S9 mix decreased this direct mutagenic activity. In contrast, preincubation of isoniazid with crude liver homogenate from mice, rats or Syrian golden hamsters for 4 h prior to plating with bacteria liberated a mutagenic compound which is equally active in both repair-deficient and repair wild-type strains (0.5-5 mg/plate). This activation pathway is independent of NADPH, is heat-sensitive and is operative only in a total liver homogenate in suspension. The highest capacity for mutagenic activation was achieved with liver homogenate from hamsters, followed by that from mice and rats. Furthermore, this mutagenic activation is paralleled by formation of hydrazine, as demonstrated in colorimetric measurements with p-dimethylaminobenzaldehyde. N-Acetyl-isoniazid is without mutagenic activity under similar conditions, and liberation of hydrazine was never detected. This means that, besides having a weak direct genetic activity, isoniazid is a promutagen, and formation of hydrazine is the first step in metabolic activation. It is concluded that the genotoxic properties of isoniazid in mammals are primarily determined by the pharmacokinetic behavior of the ultimate reactive metabolite. This result must be taken into consideration in risk assessment performed for mutagenic and carcinogenic properties of isoniazid in man.     

Genotoxicity evaluation of tetramethylbenzenes

The three tetramethyl isomers of benzene (prenitene, 1,2,3,4-; izodurene, 1,2,3,5-; and durene, 1,2,4,5-tetramethylben- zene) were studied using in vitro mutagenicity and in vivo genotoxicity tests. Potency of mutate induction by these solvents was evaluated in Salmonella typhimurium cells with, and without S9-mix made from Aroclor 1254-induced rat liver S9. The potency of induction of micronuclei (MN) and sister chromatid exchanges (SCEs) by solvents was evaluated in bone marrow of mice. Izodurene displayed mutagenic potency in strains TA97a, TA98 and TA100 only in the absence of the S9-mix. In MN tests, all three tetramethylbenzenes demonstrated no clastogenic activity on the bone marrow cells. All the tested solvents were active as genotoxic compounds in the SCE tests, demonstrating a dose-response relationships.     

Genotoxic activity of m-nitrobenzaldehyde

m-Nitrobenzaldehyde (MNB) was evaluated for mutagenic activity using the Ames microbial mutagenicity test and for its ability to induce DNA single-strand breaks in rat hepatocytes as measured by alkaline elution. MNB was tested in S. typhimurium strains TA1535, TA1537, TA1538, TA98, and TA100, both with and without pretreatment with liver microsomes (S9) isolated from rats pretreated with Aroclor 1254. MNB produced 2-fold or greater increases in revertants in TA1538, both with and without S9, and in TA100 with S9 only. A 2-fold increase in revertants was seen in TA98, but only at the highest dose tested which did not produce inhibition of background growth. MNB caused a greater than 3-fold increase in elution slope, with DNA alkaline elution assay, but only at highly cytotoxic doses and, therefore, is not considered genotoxic in this system. It is concluded that MNB possesses weak genotoxic activity.     

Selenium inhibition of benzo[a]pyrene, 3-methylcholanthrene, and 3-methylcholanthrylene mutagenicity in Salmonella typhimurium strains TA98 and TA100

Selenium (Se) decreased the mutagenicity of benzo[a]pyrene (BP), 3-methylcholanthrene (3MC), and 3-methylcholanthrylene (3MCE) in Salmonella typhimurium strains TA98 and TA100. Metabolism of BP, 3MC and 3MCE to mutagens was accomplished with the liver S9 fraction from Aroclor 1254-treated male Sprague-Dawley rats. Exposure of the bacteria to 4 nmoles BP, 10 nmoles 3MC, or 10 nmoles 3MCE in the presence of S9, and up to 200 nmoles Se as Na2SeO3 resulted in decreased mutagenicities up to 39, 66 and 60% of their respective control activities without Se in TA98 and up to 46, 52 and 64% of their respective control activities without Se in TA100. Se (200 nmoles) alone was not mutagenic in strains TA98 or TA100 with or without S9. BP, 3MC and 3MCE were not mutagenic in either strain without S9. None of the tested concentrations of BP, 3MC, 3MCE and Se were cytotoxic. Assays of the aryl hydrocarbon hydroxylase (AHH) activity in the S9 preparation revealed decreased AHH activity with increase in Se concentration. The decreased mutagenicity and AHH activity were Se (as Na2SeO3) dependent and could not be duplicated by sulfur (S as Na2SO3). Inhibition of AHH activity by Se provides an explanation of the mechanism of Se inhibition of BP, 3MC and 3MCE mutagenicities in S. typhimurium TA98 and TA100.     

The hair-dye reagent 2-(2',4'-diaminophenoxy)ethanol is mutagenic to Salmonella typhimurium

A new hair-dye ingredient, 2-(2',4'-diaminophenoxy)ethanol (2,4-DAPE), was described as being devoid of any genotoxic activity on the basis of a multi-laboratory study. Since 2,4-DAPE is a close analogue of 2,4-diaminoanisole (2,4-DAA), which is mutagenic and carcinogenic, we tested this claim by assaying 2,4-DAPE for bacterial mutagenicity. Two samples of 2,4-DAPE X 2HCl were synthesized by reduction of the corresponding dinitrophenoxyethanol and identity and purity were established by elemental analysis, NMR spectrometry, mass-spectrometry, UV-spectrophotometry, TLC and HPLC. Fresh aqueous solutions of 2,4-DAPE X 2HCl were assayed in several separate plate tests using S. typhimurium TA1538, TA97, TA98 and TA100, and E. coli WP2uvrA (pKM101), 3 plates per dose and 0%, 4%, 10% and 30% Aroclor 1254-induced rat-liver S9 in S9 mixes. We obtained negative results in TA100 and E. coli. Reproducible, statistically significant dose-related increases in revertants (up to 14 times the background) were obtained in frame-shift mutants of S. typhimurium in the dose range 10-80 micrograms per plate. Mutagenicity was S9-dependent, significant increases in revertants being obtained only with 50 microliter per plate or more of S9. 2,4-DAPE induced significant mutagenic effects at doses of less than 1 micrograms per ml in TA1538 and TA98 in fluctuation tests using 2% S9 in the S9 mix. In plate tests, 2,4-DAPE was less mutagenic (by a factor of about 8) than 2,4-DAA, which gave the highest mutant yields with 20 microliter S9 per plate (4% S9 in the S9 mix). 2,4-DAPE obtained commercially was about 8 times more mutagenic than our sample of 2,4-DAPE. After purification, the commercial product, now chromatographically identical with our own sample, gave plate-test results close to those obtained for our samples of 2,4-DAPE. A review of the published reports (in which 2,4-DAPE was claimed to be inactive in a variety of short-term tests) revealed: (a) the use of protocols for bacterial mutagenicity testing which, in the light of our own results, were probably too limited in scope, especially in the choice of conditions for metabolic activation; (b) insufficient information on the identification and purity of the samples of 2,4-DAPE tested in the published collaborative study.     

Mutagenicity of some derivatives of dipyrido[1,2-a:3',2'-d]imidazoles in Salmonella typhimurium with metabolic activation by rat liver and small intestine subcellular fractions

The mutagenic effect of 2-amino-dipyrido[1,2-a:3',2'-d]imidazole (Glu-P-2) was compared with that of the 3-amino, 3-nitro, or 3-N-hydroxylated derivatives of the same base ring with methyl groups at positions 4 and 6 of the molecule. The compounds were tested in Salmonella typhimurium strain TA98 without metabolic activation and in the presence of different concentrations of subcellular fractions from livers or small intestines of rats pretreated with different P448/P450 inducers. The 4,6-dimethyl compounds are always more mutagenic than Glu-P-2. Pretreatment with Aroclor 1254 (ARO) is the most effective inducer in the activation of the 2- and 3-amino compounds by liver S9, whereas the same fraction decreases the mutagenicity of the 3-nitro derivative. S9 from small intestine increased the mutagenic effect of the 3-nitro and 3-N-hydroxylated compounds, but it was unable to activate the amino compounds.     

1-Hydroxypyrene as an indicator of the mutagenicity of coal tar after activation with human liver preparations

Liver S9 fractions were prepared from male Wistar rats, either non-induced or induced with Aroclor 1254 and from 5 human kidney transplant donors. The preparations were compared for their ability to metabolize the premutagens present in coal tar to mutagenic metabolites in the Salmonella mutagenicity assay towards strain TA98. Low levels of mutagenicity of coal tar were seen with human S9 preparations. The differences between the S9 mix of the 5 donors in capacity to activate premutagens were approximately 6-fold. The activation of coal tar by rat liver S9 preparations was higher than by the human S9 preparations. The metabolic conversion of pyrene in coal tar to 1-hydroxypyrene by the same human S9 preparations was determined in a parallel assay. 3 human preparations showed a high correlation between the formation of 1-hydroxypyrene and bioactivation of coal tar to mutagenic metabolites. The slope values of the individual regression lines were equal, suggesting that 1-hydroxypyrene is a good indicator for the activation of premutagens present in coal tar.     

Arylamine activation following chronic ethanol ingestion by rats: studies on the liver S9, microsomal and cytosolic fractions and comparison with Aroclor 1254 pretreatment

That enzyme fractions derived from animals chronically fed alcohol can alter the metabolism of carcinogenic xenobiotic compounds has been documented. To further understand this relationship the mutagenicity of 3 aromatic amines was determined in the Ames test, employing activation systems derived from rats maintained on an alcohol-containing liquid diet, an isocaloric control liquid diet or Aroclor 1254-pretreated animals fed standard laboratory chow. Depending upon protein and substrate concentrations, S9 from ethanol-fed rats was 30-50% less efficient than S9 from pair-fed rats in activating arylamines (2-aminofluorene, 2-aminoanthracene and 2-acetylaminofluorene) to mutagens in Salmonella typhimurium TA98 and TA100. Cytosolic fractions from ethanol-fed animals always resulted in greater arylamine activation than that of controls whereas the opposite was true of the microsomal compartment in which the ethanol-treated group was consistently less active than the controls. The cytosolic N-acetyltransferase activities with respect to 2 different substrates, isoniazid and 2-aminofluorene, were unaffected by ethanol consumption, indicating that this activity probably does not account for the different activation profiles exhibited by the ethanol and pair-fed cytosolic systems. Both the cytosolic and microsomal compartments are required for maximal expression of the mutagenicity of each arylamine however, each compartment can activate arylamines independently of the other. Reconstituting cytosol with microsomes from ethanol- and pair-fed rats, but not Aroclor-pretreated rats, resulted in a synergistic activation of the aromatic amines and displayed an effect similar to that of S9. Compared to Aroclor pretreatment and pair-fed controls, microsomes from ethanol-fed rats displayed the least capacity for activating any of the arylamines to mutagens. Microsomes from Aroclor-pretreated rats accounted for at least 80% of the S9-mediated activation of each of the arylamines to mutagenic metabolites which was in marked contrast to the contribution of the microsomal fractions to the S9 activity in the ethanol- (5-20% of S9 activity) and pair-fed systems (22-30% of S9 activity). The data indicate that 2 opposing reactions occur in S9, a cytosolic activity that augments and a microsomal activity that attenuates the mutagenicity of arylamines. Both activities are modified by ethanol consumption and Aroclor pretreatment.     

Mutagenicity of N,N'-dimethylurea and methylamine hydrochloride in the Ames Salmonella/microsome test: absence of mutagenic response.

Methyl isocyanate (MIC) in aqueous solution forms methylamine (MA) and N,N'-dimethylurea (DMU). MA in buffered system further converts into its salt form, methylamine hydrochloride (MAH). Therefore, MAH and DMU were evaluated for their mutagenic activity in the in vitro Ames Salmonella/microsome mutagenicity test. The liquid preincubation protocol was followed, using tester strains TA98, TA100 and TA104 of Salmonella typhimurium, in the presence of 0, 5, 15 and 30% Aroclor 1254-induced rat liver S9 mixture. DMU and MAH did not induce a mutagenic response in any of the tester strains, both in the presence and in the absence of S9 mixture. The results therefore confirm that MIC in its native form or as its unknown metabolites is responsible for the mutagenic activity reported earlier by us in the his tester strains TA100 and TA104 of Salmonella typhimurium (Mutation Res., 204 (1988) 123-129) and not due to its hydrolysis products, MA or DMU.     

Mutagen levels in urine from snuff users, cigarette smokers and non tobacco users--a comparison

The mutagenic activity of concentrates of urine from snuff users, cigarette smokers and non tobacco users has been investigated. A concentration procedure involving use of Sep-Pak C18 columns and elution with methylene chloride was used. The concentrates were assayed for mutagenicity towards strain TA98 of Salmonella typhimurium, both in the presence and absence of a metabolic activation system, the post-mitochondrial liver fraction (S9) from Aroclor 1254 induced rats. The mean mutagenic activity of smokers' urine concentrates was 8.6 X 10(3) revertants per 24 h and significantly higher than the corresponding values for snuff users, abstinent snuff users and non tobacco users, which were (1.3, 1.3 and 0.9) X 10(3), respectively. No significant difference in mutagenic activity was found between urine from snuff users, whether using or abstaining from snuff, and urine from non tobacco users. It could thus be concluded that the level of urinary mutagens, isolated by adsorption on Sep-Pak C18 columns, is not elevated by habitual usage of Swedish wet snuff.     

The mutagenic and clastogenic activity of tobacco smoke

Employing the Salmonella/microsome mutagenicity assay it was established that the mutagenic effect of tobacco smoke (TS) (240 cm3 in a 16-l glass chamber, at 1 min or 5 min exposure time) in S. typhimurium TA98 depended on the type of S9 mix used. Addition of S9 mix obtained from the liver of 3-methylcholanthrene- or Aroclor-1254-pretreated rats but not from the liver of phenobarbital-pretreated or untreated rats was required to demonstrate the mutagenic activity of TS. One might suggest that polycyclic aromatic hydrocarbons were involved in TS-induced mutagenesis in S. typhimurium TA98. In addition, treatment of BDF1 mice with TS (600 cm3 TS in a 14-l glass chamber, 2-6 exposures of 30 min each with a 1-min interval between them during which a total change of the air was made) caused an up to 3.5-fold increase of the number of micronucleated polychromatic erythrocytes (PCE) in mouse bone marrow detected 24 h after the TS exposure. Furthermore, a stable 2-5-fold elevation of the number of micronucleated normochromatic erythrocytes (NCE) was detected in the peripheral blood of mice treated daily (2 x 30 min) with TS, starting 48 h after the first TS exposure. The application of the micronucleus test in mouse peripheral blood, a more convenient and useful approach for detecting the chronic clastogenic activity of TS, allowed us to establish the cumulative genotoxic effect of TS in mice.     

Mutagenicity of 2-methylacrolein, 2-ethylacrolein and 2-propylacrolein in Salmonella typhimurium TA100. A comparative study.

The C2-alkylated acrolein derivatives 2-methylacrolein, 2-ethylacrolein and 2-propylacrolein are mutagenic in Salmonella typhimurium TA100. They are direct mutagens, their mutagenic potency being inversely proportional to the size of the alkylating substituent in the C2 position. In the presence of S9 mix, the mutagenicity of all these substances is considerably reduced; the reduction in mutagenicity is inversely proportional to the direct mutagenic potential of the substance. As shown for 2-methylacrolein, the reduction in mutagenicity is dependent on the concentration of S9 in the S9 mix and is not significantly influenced by heat inactivation of the S9 mix or by addition of TCPO, an inhibitor of epoxide hydrolase, to the testing system. There are no indications of enzymatic activation by the metabolizing microsomal system.