Aliphatic halogenated hydrocarbons produce volatile Salmonella mutagens

A review of the genotoxicity of triallate

Triallate is a selective herbicidal chemical used for control of wild oats in wheat. It has an extensive genotoxicity database that includes a variety of in vitro and in vivo studies. The chemical has produced mixed results in in vitro assay systems. It was genotoxic in bacterial mutation Ames assays, predominantly in Salmonella typhimurium strains TA100 and TA1535 in the presence of S9. Weaker responses have been observed in TA100 and TA1535 in the absence of S9. Mixed results have been observed in strain TA98, whereas no genotoxicity has been observed in strains TA1537 and TA1538. The presence and absence of S9 and its source seem to play a role in the bacterial response to the chemical. There have also been conflicting results in other test systems using other bacterial genera, yeast, and mammalian cells. Chromosome effects assays (sister-chromatid exchange and cytogenetics assays) have produced mixed results with S9 but no genotoxicity without S9. Triallate has not produced any genotoxicity in in vitro DNA damage or unscheduled DNA synthesis assays using EUE cells, human lymphocytes, and rat and mouse hepatocytes. In a series of in vivo genotoxicity assays (cytogenetics, micronucleus, dominant lethal, and unscheduled DNA synthesis), there has been no indication of any adverse genotoxic effect. Metabolism data indicate that the probable explanation for the differences observed between the in vitro studies with S9 and without S9 and between the in vitro and the in vivo studies is the production of a mutagenic intermediate in vitro at high doses of triallate is expected to be at most only transiently present in in vivo studies. The weight of evidence strongly suggests that triallate is not likely to exert mutagenic activity in vivo due to toxicokinetics and metabolic processes leading to detoxification.

Determination of the vaporization of solutions of mutagenic antineoplastic agents at 23 and 37 degrees C using a desiccator technique

This study evaluated the ability of mutagenic antineoplastic agents to vaporize at room temperature (23 degrees C) and 37 degrees C. A bacterial mutagenicity assay was used to determine the mutagenicity of these agents in the vapor phase. Open plates of bacteria were exposed to varying amounts of drug solutions in sealed glass containers for 24h. The drug solutions were prepared as they would be for patient treatment and were tested at 0.25, 0.5 and 1.0 ml of each drug solution per 10 l of air. Following exposure, the plates exposed at 23 degrees C were incubated an additional 48 h at 37 degrees C to allow for expression of mutations. Those exposed at 37 degrees C were incubated for an additional 24h at 37 degrees C. Carmustine, cyclophosphamide, ifosfamide, thiotepa, and mustargen demonstrated vaporization at 37 degrees C. Carmustine and mustargen also demonstrated significant vaporization at 23 degrees C, while cyclophosphamide demonstrated a 50% increase in revertants at this temperature. In addition, sodium azide, a known mutagen used as a control was also mutagenic as a vapor at both temperatures. Doxorubicin, cisplatin, etoposide, 5-fluorouracil and mitomycin were not detected as vaporizing in this assay. The study found that vaporization of standard solutions of some antineoplastic agents is possible at room temperature and increases as the temperature increases. Therefore, vaporization of spilled antineoplastic agents may present an additional route of exposure to healthcare workers through inhalation.

Genotoxic effects and chemical compositions of four creosotes

Four creosotes used in Finland for impregnating wood were tested in the Ames Salmonella test, the SCE test and the SOS chromotest. Compounds volatile at 37 degrees C were assayed using the taped plate testing protocol. The creosotes were fractionated according to their natural boiling ranges and the fractions were tested in the Ames Salmonella assay. Chemical compositions of creosotes and fractions were determined by high resolution gas chromatography/mass spectrophotometry techniques and by reversed phase high performance liquid chromatography. Mutagenic activities were shown to reside in fractions having the highest boiling point ranges (greater than 290 degrees C). The concentrations of mutagenic polycyclic aromatic hydrocarbons in creosotes and in some of their corresponding distillation fractions, when compared with mutagenic activities, indicated synergistic or antagonistic interactions.

Mutagenicity of bi-, tri- and tetra-cyclic aromatic hydrocarbons in the "taped-plate assay" and in the conventional salmonella mutagenicity assay

Aromatic hydrocarbons in the range of 1-4 nuclear rings were examined for mutagenicity in the so-called "taped-plate assay". This modification of the Ames assay is particularly equipped for the detection of volatile mutagens. Of the many compounds tested only phenanthrene, pyrene, benzo[c]phenanthrene and benzoacenaphthylene were positive in this assay. The present data underline the exceptional behaviour of fluoranthene by being a rather potent bacterial mutagen with a volatile nature (as found in a previous study).

Fluoranthene, a volatile mutagenic compound, present in creosote and coal tar

Creosote, a coal-tar distillation product, contains mutagens which are volatile at 37 degrees C. After distillation of creosote we found that these volatile mutagens were present in the distillation fraction with the highest boiling range (greater than 360 degrees C). The "volatile mutagenic activity" was connected with the presence of fluoranthene, a polycyclic aromatic hydrocarbon. Commercially available fluoranthene was positive in the so-called "taped-plate assay" (the test system used for the detection of volatile mutagens) towards the strains TA98 and TA100 in the presence of S9 mix. The tested creosote and coal tar contained fluoranthene in concentrations of 5.2 and 2.2%, respectively.

Genotoxic evaluation of the offgassing products of particle board

It has been recognized that people are spending more time indoors and that pollutants are being found in elevated concentrations in this environment. Because the constituents of indoor air pollution can vary relative to a large number of factors, the nature of the indoor environment is extremely difficult to study. Of the materials used in construction of buildings which can elute complex mixtures of organic compounds, products such as particle board, plywood and insulation are known to release formaldehyde into the indoor environment. We have employed a modification of the Ames Salmonella/microsome assay with both DNA repair-proficient and -deficient strains and determined that one such material, particle board, emitted mutagenic and genotoxic substances. The materials offgassing from the particle board demonstrated a dose-related response in both mutagenicity and toxicity. It was also observed that incubation at 37 degrees C produced a decrease in both endpoints which was related to time of incubation. In addition, detectable amounts of twelve other organic compounds were identified as offgassing from the incubated particle board.

Detection of volatile mutagens in creosote and coal tar

Creosote and coal tar were examined for the presence of volatile mutagens by use of the so-called "taped plate assay". Application of this method, recently published by Distlerath et al., reveals that vapour escaping from creosote and coal tar at 37 degrees C was able to revert the Salmonella typhimurium strains TA98 and TA100 in the presence of S9 mix. The simplicity of this method makes it useful for routine screening of industrial fluids or solid products for the presence of volatile mutagens.

Metabolic activation of 3-(2-chloroethoxy)-1,2-dichloropropene: a mutagen structurally related to diallate, triallate, and sulfallate

3-(2-Chloroethoxy)-1,2-dichloropropene (CP), a Salmonella promutagen that was recently isolated from a sample of residue organics previously concentrated from drinking water, is structurally related to three other chlorinated promutagens, the S-chloroallyl thiocarbamate herbicides diallate, triallate, and sulfallate. These four chloroallyl ether compounds were found to be similar with respect to strain specificity, potency, and requirement for specific metabolic activation. The 9,000g supernatant (S9) fractions from polychlorinated biphenyl Aroclor 1254- or phenobarbital-induced rats metabolized the four chloroallyl ethers to mutagenic products, whereas S9 from 3-methylcholanthrene-induced or uninduced rats did not. The metabolic activation of CP, diallate, and triallate to mutagens was catalyzed by the 100,000g microsomal pellet of S9 alone, but the activation of sulfallate to mutagenic metabolites required both microsomal and cytosolic fractions of S9. Direct-acting (minus S9) mutagenic metabolites of diallate and triallate could be extracted into methylene chloride from S9 incubation mixtures. Incubations containing S9 and either sulfallate or CP did not yield methylene chloride-extractable metabolites with direct-acting mutagenic activity. On the basis of these results and those from previous studies on the metabolism of diallate, triallate, and sulfallate, a tentative model for the metabolic activation of CP is proposed in which this chloroallyl ether undergoes alpha-carbon hydroxylation to form multiple mutagenic products.