Papers by Larry D Claxton
Dilute mixtures of automobile emissions (comprising 50% exhaust and 50% surrogate evaporative emi... more Dilute mixtures of automobile emissions (comprising 50% exhaust and 50% surrogate evaporative emissions) were irradiated in a 22.7 m 3 smog chamber and tested for mutagenic activity by using a variant of the Ames test. The exhaust was taken from a single vehicle, a t 977 Ford Mustang equipped with a catalytic converter. Irradiated and nonirradiated gas-phase emissions were used in exposures of the bacteria, Salmonella typhimurium, strains TA100 and TA98. A single set of vehicular operating conditions was used to perform multiple exposures. The mutagenic activities of extracts from the particulate phase were also measured with the standard plate incorporation assay. (In most experiments only direct-acting mutagenic compounds were measured.) The gas-phase data for TAtOO and TA98 showed increased activity for the irradiated emissions when compared to the nonirradiated mixture, which exhibited negligible activity with respect to the control values. The particulate phase for both the irradiated and nonirradiated mixtures showed negligible activity When results were compared to the control values for both strains. However, the experimental conditions limited the amount of extractable mass which could be collected in the particulate phase. The measured activities from the gas phase and particulate phase were converted to the number of revertants per cubic meter of effluent (i.e. the mutagenic density) to compare the contributions of each of these phases to the total mutagenic activity for each strain. Under the experimental conditions of this study, the mutagenic density of the gas-phase component of the irradiated mixture contributed approximately two orders of magnitude more of the total TA100 activity than did the particulate phase. For TA98 the gas-phase component contributed approximately one order of magnitude more. However, caution must be exercised in extrapolating these results to urban atmospheres heavily impacted by automotive emissions, because the bacterial mutagenicity assay was used as a screening method, and additional assays using mammalian systems have not yet been conducted. In addition, only limited number of conditions were able to be tested. The significance and limitations of the results are discussed.
Salmonella typhimurium, strain TAIOO was ex in the exposure chamber and the exposure time. posed ... more Salmonella typhimurium, strain TAIOO was ex in the exposure chamber and the exposure time. posed to a series of peroxyacyl nitrates including The mutagenic activity for each compound deter peroxyacetyl nitrate (PAN), peroxyprapionyl ni mined from the dose-response relationship gave trate (PPN). peroxybutyryl nitrate (PBN). peroxy values ranging from 250 (PBN) to 6,500 (PBzN) benzoyl nitrate (PBzN). and chloroperoxyacetyl revertants/....mol. The mutagenic activity for nitrate (CPAN). Gas-phase concentrations for CPAN could not be determined, due to an inter the individual exposures were in the high part ference from chloroacetaldehyde. The difficulties per billion by volume ppbv range. The dose was of quantifying the acfual gas-phase chemical determined from the deposition rate and mea dose the bacferia are exposed to in this variant sured from the net decrease of the test compound of the Ames test are delineated.
Dilute mixtures of wood combustion emissions (with and without additional NO,) were irradiated in... more Dilute mixtures of wood combustion emissions (with and without additional NO,) were irradiated in a 22.7-m3 Teflon smog chamber. The effluent was tested for mutagenic activity by exposing Salmonella typhimurium, strains TAlOO and TA98, to the filtered gas-phase components. The particulate matter was tested by using the plate incorporation procedure. Without added NO,, irradiated dilute wood smoke showed a measurable increase in mutagenic activity for gas-phase products only. Additional NO, was added in other irradiations to enhance the formation of gas-and particulate-phase products. Although only lower and upper limits were obtainable, the gas-phase products showed considerably more activity (1.1-8.2 revertants/pg) in TAlOO exposures than did the particulate product extracts. With TA98 the activities of both phases were comparable on a mass basis. Since the total quantity of gas-phase components was greater than the particulate-phase components, the mutagenic activity on a volume basis was greater for the gas phase.
Literature Cited 7439-93-2. affect the overall variability in ash composition. Extrapolations con... more Literature Cited 7439-93-2. affect the overall variability in ash composition. Extrapolations concerning sampling designs might be made to other coal-fired plants, provided extreme differences do not exist in the plant operations. For example, a highly variable coal source might result in time variabilities in ash composition greater than those measured in these studies. The basic approach and equations can be used in sampling designs for other waste discharges from point sources, provided the time variability can be described by a normal distribution.
The metabolism of r 14 C}-1-nitropyrene by human, rat, and mouse intestinal microflora and a bioa... more The metabolism of r 14 C}-1-nitropyrene by human, rat, and mouse intestinal microflora and a bioassay-directed chemical analysis of the isolated metabolites by assaying HPLC fractions with a microsuspension reverse mutation assay were examined. r 74 Cl 1~Nitropyrene was metabolized by human, rat, and mouse intestinal microflora to 1 am inopyren e, N-acetyl-1-aminopyrene, N-formyl-1-aminopyrene, and two unknown metabolites identified as A and B. The predominant metabolite produced by human, rat, or mouse intestinal microflora following a 12-h incubation with / 14 Cl-1-nitropyrene was 1-aminopyrene, which accounted for 93, 79, and 88% of the total '4 c, respectively.
rn Dilute wood smoke from a residential wood stove was added to two 25-m3 outdoor Teflon film cha... more rn Dilute wood smoke from a residential wood stove was added to two 25-m3 outdoor Teflon film chambers. The smoke was permitted to age by itself or react with sub-ppm levels of NO2, NO2 + 03, or O3 in the presence and absence of natural sunlight. Most wood smoke particles fell into the 0.07-0.23 pm size range. The shape of the particle size distributions did not subsequently change during a 4-h reaction period. After reaction with O3 + NO,, the direct-acting bacterial mutagenicity (TA98-S9) of wood smoke extracts increased 2-10-fold. These changes occurred very rapidly. Increases were also observed when wood smoke was exposed to NO2 alone, but these increases were not as great as those resulting from combined effects of O3 + NO2. Preliminary experiments with wood smoke aged in the dark or in the light in the presence of low levels of NO, and O3 (i.e., <0.06 ppm) did not show increases in bacterial mutagenicity.
w Dilute wood smoke from a residential wood stove was added to 25-m3 outdoor Teflon chambers and ... more w Dilute wood smoke from a residential wood stove was added to 25-m3 outdoor Teflon chambers and then reacted in the dark with sub-ppm levels of O3 and NOz. Chemical fractionation of unreacted and O3 and NO2 reacted wood smoke indicated that most of the extracted mass as well as the mutagenicity was contained within the most polar fractions. The PAH fraction contributed 12-17% of the total TA98+S9 mutagenicity of unreacted wood smoke.
w Dilute wood smoke from a residential wood stove was added to 25-m3 outdoor Teflon chambers and ... more w Dilute wood smoke from a residential wood stove was added to 25-m3 outdoor Teflon chambers and then reacted in the dark with sub-ppm levels of O3 and NOz. Chemical fractionation of unreacted and O3 and NO2 reacted wood smoke indicated that most of the extracted mass as well as the mutagenicity was contained within the most polar fractions. The PAH fraction contributed 12-17% of the total TA98+S9 mutagenicity of unreacted wood smoke.
The role of the eN(CH 2 CH 2 OH) 2 group in producing a mutagenic response from 4-((3-(2-hydroxye... more The role of the eN(CH 2 CH 2 OH) 2 group in producing a mutagenic response from 4-((3-(2-hydroxyethoxy) 4-amino)phenylazo)-N,N-bis(2-hydroxyethyl)-aniline has been investigated. To accomplish this goal, a group of substituted 4,4 0 -diaminoazobenzene dyes was synthesized, and their structures were confirmed using 1H NMR, TOF-LC-ESI mass spectrometry, and combustion analysis. Mutagenicity was determined using the standard Ames test in Salmonella strains TA98, TA100, and TA1538 with and without S9 enzyme activation. The results of this study provide evidence that the mutagenicity of the parent dye arises from the metabolic cleavage of N-hydroxyethyl groups to give the corresponding eNHCH 2 CH 2 OH and eNH 2 substituted monoazo dyes as direct-acting mutagens. All 5 of the dyes studied were mutagenic at various levels with and without S9 enzyme activation in TA1538. In addition, the results show that removing one N-hydroxyethyl group and capping both eOH groups in the parent dye did not affect mutagenicity, whereas removing both N-hydroxyethyl groups produced a strong directacting mutagen in all three bacterial strains. Increasing the length of the N-alkyl chain from two to three carbon atoms eliminated mutagenicity in TA98 without S9 activation.
The role of the eN(CH 2 CH 2 OH) 2 group in producing a mutagenic response from 4-((3-(2-hydroxye... more The role of the eN(CH 2 CH 2 OH) 2 group in producing a mutagenic response from 4-((3-(2-hydroxyethoxy) 4-amino)phenylazo)-N,N-bis(2-hydroxyethyl)aniline has been investigated. To accomplish this goal, a group of substituted 4,4 0 -diaminoazobenzene dyes was synthesized, and their structures were confirmed using 1H NMR, TOF-LC-ESI mass spectrometry, and combustion analysis. Mutagenicity was determined using the standard Ames test in Salmonella strains TA98, TA100, and TA1538 with and without S9 enzyme activation. The results of this study provide evidence that the mutagenicity of the parent dye arises from the metabolic cleavage of N-hydroxyethyl groups to give the corresponding eNHCH 2 CH 2 OH and eNH 2 substituted monoazo dyes as direct-acting mutagens. All 5 of the dyes studied were mutagenic at various levels with and without S9 enzyme activation in TA1538. In addition, the results show that removing one N-hydroxyethyl group and capping both eOH groups in the parent dye did not affect mutagenicity, whereas removing both N-hydroxyethyl groups produced a strong directacting mutagen in all three bacterial strains. Increasing the length of the N-alkyl chain from two to three carbon atoms eliminated mutagenicity in TA98 without S9 activation. Dyes and Pigments xxx (2010) 1e9 Please cite this article in press as: Jeong E, et al., Synthesis and characterization of selected 4,4 0 -diaminoalkoxyazobenzenes, Dyes and Pigments (2010),
An in vitro approach was used to measure the genotoxicity of creosote-contaminated soil before an... more An in vitro approach was used to measure the genotoxicity of creosote-contaminated soil before and after four bioremediation processes. The soil was taken from the Reilly Tar site, a closed Superfund site in Saint Louis Park, Minnesota. The creosote soil was bioremediated in bioslurry, biopile, compost, and land treatment, which were optimized for effective treatment. Mutagenicity profiles of dichloromethane extracts of the five soils were determined in the Spiral technique of the Salmonella assay with seven tester strains. Quantitative mutagenic responses in the plate incorporation technique were then determined in the most sensitive strains, YG1041 and YG1042. Mutagenic potency (revertants per microgram extract) in YG1041 suggested that compost, land treatment, and untreated creosote soil extracts were moderately mutagenic with Arochlor-induced rat liver (S9) but were nonmutagenic without S9. However, the bioslurry extract was strongly mutagenic and the biopile extract was moderately mutagenic either with or without S9. A similar trend was obtained in strain YG1042. The strong mutagenic activity in the bioslurry extract was reduced by 50% in TA98NR, which suggested the presence of mutagenic nitrohydrocarbons. Variation in reproducibility was 15% or less for the bioassay and extraction procedures. Bioavailability of mutagens in the biopile soil was determined with six solvents; water-soluble mutagens accounted for 40% of the total mutagenic activity and they were stable at room temperature. The mutagenic activity in the bioslurry and biopile samples was due to either the processes themselves or to the added sludge/manure amendments. The in vitro approach was effective in monitoring bioremediated soils for genotoxicity and will be useful in future laboratory and in situ studies.
Ambient air has been shown to contain numer late matter collected in Tokyo during the winters ous... more Ambient air has been shown to contain numer late matter collected in Tokyo during the winters ous hazardous pollutants, many of which are of 1988 and 1990. In addition to the conventiona I known or suspected carcinogens and mutagens.
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Papers by Larry D Claxton