Comparison of biomarkers in workers exposed to 2,4,6-trinitrotoluene.

2,4,6-Trinitrotoluene (TNT) is an important occupational and environmental pollutant. In TNT-exposed humans, notable toxic manifestations have included aplastic anaemia, toxic hepatitis, cataracts, hepatomegaly, and liver cancer. Therefore, methods were developed to biomonitor workers exposed to TNT. The workers were employed in a typical ammunition factory in China. The external dose (air levels and skin exposure), the internal dose (urinary metabolites), the biologically effective dose (haemoglobin adducts, urinary mutagenicity), biological effects (chromosomal aberrations and health effects), and individual susceptibility (genotypes of xenobiotic-metabolizing enzymes) were determined. Haemoglobin-adducts of TNT, 4-amino-2,6-dinitrotoluene (4ADNT) and 2-amino-4,6-dinitrotoluene (2ADNT), and the urinary metabolites of TNT, 4ADNT and 2ADNT, were found in all workers and in some controls. The levels of the haemoglobin-adducts or the urinary metabolites correlated weakly with the skin or air levels of TNT. The urinary mutagenicity determined in a subset of workers correlated strongly with the levels of 4ADNT and 2ADNT in urine. The haemoglobin-adducts correlated moderately with the urinary metabolites and with the urinary mutagenicity. The genotypes of glutathione S-transferases (GSTM1, GSTT1, GSTP1) and N-acetyltransferases (NAT1, NAT2) were determined. In general, the genotypes did not significantly influence the haemoglobin-adduct levels and the urine metabolite levels. However, TNT-exposed workers who carried the NAT1 rapid acetylator genotype showed an increase in urinary mutagenicity and chromosomal aberrations as compared with slow acetylators. The haemoglobin adduct 4ADNT was significantly associated with a risk of hepatomegaly, splenomegaly and cataract; urine metabolites and genotypes were not associated with health effects. These results indicate that a set of well-selected biomarkers may be more informative regarding exposure and effect than routinely performed chemical measurements of pollutants in the air or on the skin.

Chromosomal aberrations in peripheral lymphocytes of train engine drivers.

Studies of Swedish railway employees have indicated that railroad engine drivers have an increased cancer morbidity and incidence of chronic lymphatic leukemia. The drivers are exposed to relatively high magnetic fields (MF), ranging from a few to over a hundred microT. Although the possible genotoxic potential of MF is unclear, some earlier studies have indicated that occupational exposure to MF may increase chromosome aberrations in blood lymphocytes. Since an increased level of chromosomal aberrations has been suggested to predict elevated cancer risk, we performed a cytogenetic analysis on cultured (48 h) peripheral lymphocytes of Swedish train engine drivers. A pilot study of 18 engine drivers indicated a significant difference in the frequency of cells with chromosomal aberrations (gaps included or excluded) in comparison with seven concurrent referents (train dispatchers) and a control group of 16 office workers. The engine drivers had about four times higher frequency of cells with chromosome-type aberrations (excluding gaps) than the office workers (P < 0.01) and the dispatchers (P < 0.05). Seventy-eight percent of the engine drivers showed at least one cell per 100 with chromosome-type aberrations compared with 29% among the dispatchers and 31% among the office workers. In a follow-up study, another 30 engine drivers showed an increase (P < 0.05) in the frequency of cells with chromosome-type aberrations (gaps excluded) as compared with 30 referent policemen. Sixty percent of the engine drivers had one or more cells (per 100 cells) with chromosome-type aberrations compared with 30% among the policemen. In conclusion, the results of the two studies support the hypothesis that exposure to MF at mean intensities of 2-15 microT can induce chromosomal damage.

Trans-stilbene oxide-induced sister chromatid exchange in cultured human lymphocytes: influence of GSTM1 and GSTT1 genotypes.

About 50% and 15% of Caucasians lack the glutathione S-transferase M1 (GSTM1) and T1 (GSTT1) genes and the corresponding enzyme activity, respectively. Both of these polymorphisms have been shown to affect the genotoxicity of some epoxides in cultured human lymphocytes. Especially GSTT1 appears to be important in whole-blood cultures, probably because GSTT1 activity is high in erythrocytes. The in vitro genotoxicity of trans-stilbene oxide (TSO), a model substrate for GSTM1, has been shown to depend on individual GSTM1 activity. The potential role of GSTM1 genotype, and the possible interference of GSTT1 genotype, has not previously been examined in this context. We have studied TSO-induced sister chromatid exchanges (SCEs) in 72 h whole-blood lymphocyte cultures from 24 healthy human donors, representing different combinations of GSTM1 and GSTT1 positive and null genotypes. TSO clearly increased SCEs in cultures of all donors. The mean number of SCEs per cell induced by 75 and 150 microM TSO was, respectively, 1.5- and 1.3-times higher in cultures of GSTM1 null than GSTM1 positive donors. In another experiment, GSTM1 null individuals showed, in comparison with GSTM1 positive subjects, a 1.8-fold SCE induction by 50 microM TSO. GSTT1 genotype did not have an unequivocal effect. Our findings suggest that the lack of the GSTM1 gene, resulting in reduced detoxification capacity, increases individual sensitivity to the genotoxic effects of TSO.

Chromosome aberrations in pesticide-exposed greenhouse workers.

OBJECTIVES: The aim of this study was to investigate the possibility of subtoxic exposure to pesticides causing chromosome aberrations in greenhouse workers. METHODS: In a cross-sectional and prospective study design chromosome aberration frequencies in cultured lymphocytes were examined for 116 greenhouse workers exposed to a complex mixture of almost 50 insecticides, fungicides, and growth regulators and also for 29 nonsmoking, nonpesticide-exposed referents. RESULTS: The preseason frequencies of chromosome aberrations were slightly but not statistically significantly elevated for the greenhouse workers when they were compared with the referents. After a summer season of pesticide spraying in the greenhouses, the total frequencies of cells with chromosome aberrations were significantly higher than in the preseason samples (P=0.02) and also higher than for the referents (P=0.05). This finding was especially due to an increased number of cells with chromatid gaps between the first and second samples (P=0.001). The results may reflect an additive genotoxic effect of the spraying season, for which the use of insecticides and growth regulators (but not fungicides) culminates. The highest elevation in the risk of chromatid gaps was observed for persons who did not use gloves during re-entry activities such as nipping, cutting, pricking, and potting (risk ratio 2.88, 95% confidence interval 1.63-5.11). CONCLUSIONS: The present results suggest a genotoxic effect from a complex subtoxic occupational pesticide exposure. In general, the findings indicate the importance of personal protection, during high-exposure re-entry activities, in preventing pesticide uptake and genetic damage.

Chromosomal aberrations in humans induced by urban air pollution: influence of DNA repair and polymorphisms of glutathione S-transferase M1 and N-acetyltransferase 2.

We have studied the influence of individual susceptibility factors on the genotoxic effects of urban air pollution in 106 nonsmoking bus drivers and 101 postal workers in the Copenhagen metropolitan area. We used the frequency of chromosomal aberrations in peripheral blood lymphocytes as a biomarker of genotoxic damage and dimethylsulfate-induced unscheduled DNA synthesis in mononuclear WBCs, the glutathione S-transferase M1 (GSTM1) genotype, and the N-acetyltransferase 2 (NAT2) genotype as biomarkers of susceptibility. The bus drivers, who had previously been observed to have elevated levels of aromatic DNA adducts in their peripheral mononuclear cells, showed a significantly higher frequency of cells with chromosomal aberrations as compared with the postal workers. In the bus drivers, unscheduled DNA synthesis correlated negatively with the number of cells with gaps, indicating a protective effect of DNA repair toward chromosome damage. Bus drivers with the GSTM1 null and slow acetylator NAT2 genotype had an increased frequency of cells with chromosomal aberrations. NAT2 slow acetylators also showed elevated chromosomal aberration counts among the postal workers. Our results suggest that long-term exposure to urban air pollution (with traffic as the main contributor) induces chromosome damage in human somatic cells. Low DNA repair capacity and GSTM1 and NAT2 variants associated with reduced detoxification ability increase susceptibility to such damage. The effect of the GSTM1 genotype, which was observed only in the bus drivers, appears to be associated with air pollution, whereas the NAT2 genotype effect, which affected all subjects, may influence the individual response to some other common exposure or the baseline level of chromosomal aberrations.

Molecular cytogenetic analysis of buccal cells and lymphocytes from benzene-exposed workers.

Benzene is a well-characterized human carcinogen and clastogen still present in both the occupational and general environment. However, the levels of benzene encountered today are, in most cases, relatively low and new methods, more specific and sensitive than classical cytogenetics, are probably needed to assess if current benzene exposures pose a genotoxic risk to human health. Bearing in mind the leukaemogenic action of benzene, blood lymphocytes appear to be a suitable cell system for biomonitoring studies. Buccal epithelium is an alternative source of tissue for monitoring human exposure to inhaled occupational and environmental genotoxicants. New molecular cytogenetic techniques allowing us to specifically study clastogenic or aneugenic events in human cells may provide the additional sensitivity required. In the present study, fluorescence in situ hybridization was used to examine the content of micronuclei (MN) (using the pan-centromeric DNA probe SO-alphaAllCen) in lymphocytes and buccal cells and to detect numerical abnormalities of chromosome 9 (using a chromosome 9 centromere-specific alphoid DNA probe) in buccal cells from a population occupationally exposed to benzene in an Estonian petrochemical plant. Age-matched Estonian volunteers were used as a control group. Individual benzene exposure levels were estimated to be around 1 p.p.m. (8 h time-weighted average). No increases in the frequency of total MN, MN harbouring whole chromosomes or acentric chromosomal fragments or chromosome 9 numerical abnormalities were detected in relation to benzene exposure in the present study. The lack of positive results was consistent in both buccal cells and lymphocytes, indicating that the benzene exposure levels encountered did not induce detectable clastogenic or aneugenic effects in the exposed workers. Other variables and confounding factors, such as age, smoking or alcohol consumption, did not influence any of the multiple cytogenetic biomarkers analysed.

Induction of sister chromatid exchange by 3,4-expoxybutane-1,2-diol in cultured human lymphocytes of different GSTT1 and GSTM1 genotypes.

The induction of sister chromatid exchanges (SCEs) by a 48-h treatment with 3,4-epoxybutane-1,2-diol (EBD), a metabolite of 1,3-butadiene, was studied in whole-blood lymphocyte cultures of 22 human donors with known genotypes of two polymorphic glutathione S-transferases (GSTs), GSTT1 and GSTM1. For both genes, donors representing a homozygous 'null' genotype lacking the respective GST gene and isozyme and a 'positive' genotype with at least one intact gene and GST activity were included. The mean frequencies of SCE/cell were similar in all genotype groups: GSTT1 null (n = 10) (mean 22.0 for 250 microM and 32.9 for 500 [corrected] microM of EBD), GSTT1 positive (n = 14) (21.3 and 34.6, respectively), GSTM1 null (n = 10) (20.3 and 33.5) and GSTM1 positive donors (n = 15) (20.6 and 34.8). At 500 microM concentration of EBD, the lymphocyte cultures of all donors showed a significantly decreased replication index. No differences in EDB-induced SCEs or in replication index could be associated with the GSTM1 and GSTT1 genotypes either separately or in combination. When SCE induction by EBD was compared to that of two other known epoxide metabolites of butadiene, 1,2:3,4-diepoxybutane (DEB) was effective at concentrations over two orders of magnitude lower than EBD or 1,2-epoxy-3-butene (MEB). It is concluded that EBD is an efficient inducer of SEC in cultured human lymphocytes, although not quite as effective as MEB and clearly less effective than DEB. Contrary to previous findings with DEB and MEB, the polymorphic GSTM1 and GSTT1 do not appear to be involved in the detoxification of EBD in human lymphocytes.

Role of GSTT1 and GSTM1 genotypes in determining individual sensitivity to sister chromatid exchange induction by diepoxybutane in cultured human lymphocytes.

The individual genotoxic response of cultured human lymphocytes to diepoxybutane (DEB), an epoxide metabolite of 1,3-butadiene, shows a bimodal distribution. Blood donors can be classified as either DEB-sensitive or DEB-resistant on the basis of the frequency of sister chromatid exchanges (SCEs) induced by DEB in whole-blood lymphocyte cultures. The genetic basis of this phenomenon has thusfar been unknown. To investigate if differences in the ability of individuals to detoxify DEB could explain the bimodal response, sister chromatid exchanges (SCEs) induced by a 48-h treatment with DEB (2 and 5 microM) were analyzed in whole-blood lymphocyte cultures of 20 human donors with known genotypes of two polymorphic glutathione S-transferases (GSTs), GSTT1 and GSTM1. Both polymorphisms include a homozygous null genotype lacking the respective GST gene and isozyme. The mean frequency of SCEs/cell was 1.6 times higher among GSTT1 null donors (n = 8) than GSTT1 positive donors (n = 12) at both 2 microM DEB (mean 67.3 versus 40.9) and 5 microM DEB (mean 123.2 versus 77.5), with no overlapping in DEB-induced individual SCE frequencies between the two genotypes. Thus, all DEB-sensitive individuals were of the GSTT1 null genotype, while all DEB-resistant persons had a detectable GSTT1 gene. A significant (P < 0.05) negative correlation (r = -0.65 at 5 microM, r = -0.56 at 2 microM) was obtained in the GSTT1 positive donors between DEB-induced individual SCE frequency and RBC GSTT1 activity, measured by formaldehyde formation from dichloromethane; the GSTT1 null individuals showed no GSTT1 activity. At 5 microM DEB, the lymphocyte cultures of the GSTT1 null donors also had a significantly decreased replication index, indicating an impact of GSTT1 genotype on the cytotoxicity of DEB. No influence on DEB-induced SCEs or cytotoxic effects was observed for GSTM1 genotype. It is concluded that sensitivity to in vitro SCE induction by DEB is explained by the lack of GSTT1.

Influence of GSTM1 genotype on sister chromatid exchange induction by styrene-7,8-oxide and 1,2-epoxy-3-butene in cultured human lymphocytes.

Glutathione S-transferase M1 (GSTM1), catalyzing the conjugation of various reactive molecules with glutathione (GSH), shows genetic polymorphism in humans. Almost half of all Caucasians lack the GSTM1 gene, being theoretically at a higher risk from the toxic effects of substrates for GSTM1. The purpose of the present study was to investigate whether the GSTM1 genotype of lymphocyte donors influences the in vitro induction of sister chromatid exchanges (SCEs) by styrene-7,8-oxide (SO) and 1,2-epoxy-3-butene (MEB), the epoxide metabolites of styrene and butadiene respectively and potential substrates for GSTM1. SCEs induced after a 48 h treatment (started 24 h after culture initiation) by two different concentrations of SO (50 and 150 microM) and MEB (50 and 250 microM) were analyzed in cultured (72 h) lymphocytes of six GSTM1 null (gene deleted) and six GSTM1-positive (gene present) donors. Both SO and MEB were found to clearly increase SCEs. The GSTM1 genotype had no influence on SCE induction by SO. In contrast, MEB produced a higher level of SCEs among the GSTM1 null than GSTM1-positive samples. At 250 microM MEB, the GSTM1 null donors showed 31% more induced SCEs (on average seven more SCEs per cell) than the GSTM1-positive donors (P = 0.02, acetone treatment as the reference). Furthermore, the GSTM1 null genotype was associated with a slight decrease in mitotic index and replication index, regardless of the treatment. The results suggest that GSTM1-mediated GSH conjugation is an important detoxification pathway for MEB, but not for SO, in cultured human lymphocytes.

Analysis of chromosomal aberrations, sister-chromatid exchanges and micronuclei in peripheral lymphocytes of pharmacists before and after working with cytostatic drugs.

The frequencies of chromosome aberrations, SCEs and micronuclei (cytokinesis-block method) in blood lymphocytes were compared among six nonsmoking female pharmacists before and after 1 year of working with cytostatic drugs. All possible precautions were taken to avoid exposure to cytostatics, including proper protective clothing and a monitored, negative-pressured working environment with vertical laminar flow cabinet. As referents, an age-matched group of six nonsmoking female hospital workers not dealing with cytostatics was simultaneously sampled twice with the same time interval. The pharmacists showed a marginally higher mean frequency of SCEs/cell (6.3; P = 0.049) after the working period than 1 year earlier (5.8). On the other hand, the referents, with no obvious exposure, had a higher mean number of cells with chromatid-type aberrations, gaps excluded, in the second sampling (2.0%; P = 0.048) than in the first one (0.5%). In addition, a slight (P = 0.055) trend towards a higher frequency of micronucleated binucleate cells was observed in the second sampling for both the exposed and control subjects. As such findings suggest technical variation in the cytogenetic parameters, the small difference observed in SCEs for the pharmacists between the two samplings was probably not related to the cytostatics exposure. No statistically significant differences were observed for any of the cytogenetic parameters in comparisons between the pharmacists and the referents. The findings suggest that caution should be exercised in comparing results obtained from two different samplings in prospective cytogenetic studies.

Human cytogenetic biomonitoring of occupational exposure to 1,3-butadiene.

The association of occupational exposure to 1,3-butadiene and chromosomal damage in peripheral blood lymphocytes was studied in 40 workers from two production facilities. Control persons, 30 in all, were chosen from other departments of the same plants, and they were roughly matched for age and smoking habits. The exposure levels to ambient butadiene were measured both by personal sampling using diffuse monitors and by stationary sampling at production and handling sites. Chromosome aberrations (CA), micronuclei (MN) and sister-chromatid exchanges (SCE) in peripheral lymphocytes were analyzed as markers of exposure. Smoking had a slight effect on the frequency of MN, and the mean frequency of SCEs was also higher in smokers than in non-smokers. No effect of smoking, however, was seen in relation to chromosomal aberrations. No exposure related effects were seen in any of the three cytogenetic endpoints in either of the butadiene production plants, representing typical low (below 3 ppm) exposure levels of the butadiene manufacturing industry.

Chromosome aberrations in peripheral lymphocytes of workers employed in the plywood industry.

Workers employed in sawmills and in the manufacture of plywood are exposed to potentially mutagenic chemical aromatic emissions from wood. However, very little is known about the exposure to these natural wood components. In an attempt to determine whether such exposure could have clastogenic effects, a group of 13 male nonsmoking employees mainly from the beginning of the wood-processing line of three plywood mills and 15 matched nonsmoking referents were studied for chromosome aberrations in blood lymphocytes. A statistically significant elevation of the frequency of cells with chromatid-type breaks (mean 2.1%), as compared with the corresponding frequency of the referents (mean 1.0%), was observed for the lymphocytes of the wood workers. These results lend support to previous studies which suggested that wood-drying fumes may be carcinogenic.

Analysis of chromosomal aberrations, sister chromatid exchanges and micronuclei among power linesmen with long-term exposure to 50-Hz electromagnetic fields.

Chromosomal aberrations, sister chromatid exchanges (SCEs), replication indices and micronuclei in peripheral blood lymphocytes were analysed among 27 nonsmoking power linesmen with considerable long-term exposure to 50-Hz electromagnetic (EM) fields, and among 27 nonsmoking telephone linesmen serving as a reference group, pairwise matched with the exposed workers for age and geographical region. Blood samples from the two groups were collected, cultured and analysed in parallel. No differences between the groups were observed on analysis of SCEs, replication indices or micronuclei. However, the mean rate of lymphocytes with chromatid-type breaks was higher among the power linesmen (0.96% gaps excluded, 1.41% gaps included) than among the reference group (0.44% and 0.70%, respectively). The excess of aberrant cells was concentrated among those power linesmen who had worked earlier in their life. Although the interpretation is somewhat complicated by the confounding effect of previous smoking, these results suggest that exposure to 50-Hz EM fields is associated with a slight increase in chromatid breaks.

Induction of sister-chromatid exchanges by 2-aminofluorene in cultured human lymphocytes with and without erythrocytes.

2-Aminofluorene (2-AF), an indirect mutagen reported to be metabolically activated by erythrocytes in the Salmonella mutagenicity test, was studied for the induction of sister-chromatid exchanges (SCEs) in human lymphocytes in vitro with (whole-blood cultures) and without erythrocytes (isolated lymphocyte cultures). 2-AF (0.025-0.8 mM) was present in the cultures for the last 48 h of 72-h cultures. In both types of culture, SCEs increased in a dose-dependent manner, with a statistically significant elevation already at the lowest concentration of 2-AF tested and maximum responses of 2.4-fold (whole blood) and 2.1-fold (isolated lymphocytes), in comparison with mean SCEs/cell in control cultures, at 0.4 and 0.2 mM concentrations (respectively). Thus, the induction of SCEs by 2-AF was not dependent on the presence of erythrocytes. Styrene (2 mM), a positive control chemical known to require erythrocytes for efficient SCE induction in vitro, was shown to produce a 4.9-fold increase in SCEs in whole-blood cultures, but only a slight (1.3-fold) effect in isolated lymphocyte cultures. The results suggest that leukocytes, but not erythrocytes, are important in the metabolic activation of 2-AF in the human lymphocyte SCE assay.

Sister-chromatid exchanges induced by vinyl esters and respective carboxylic acids in cultured human lymphocytes.

Vinyl acetate--an efficient inducer of sister-chromatid exchanges (SCEs)--is known to be hydrolyzed in mammalian cells into acetic acid and acetaldehyde, the latter being the likely metabolite responsible for the SCE induction. As similar hydrolysis to acetaldehyde and to a carboxylic acid is also expected for other vinyl esters, five such compounds--vinyl formate, vinyl chloroformate, vinyl propionate, vinyl crotonate and vinyl-2-ethylhexanoate--and five carboxylic acids--formic acid, acetic acid, propionic acid, crotonic acid and 2-ethylhexanoic acid--were tested for their ability to induce SCEs in cultured (72 h) human lymphocytes with a 48-h treatment, starting at 24 h after culture initiation. Vinyl formate, vinyl propionate and vinyl crotonate induced a clear dose-dependent increase in the number of SCEs/cell at concentrations of 0.125-0.5 mM and vinyl chloroformate at 0.063-1 mM, i.e., at roughly the same concentration range as vinyl acetate and acetaldehyde. Vinyl-2-ethylhexanoate required slightly higher concentrations (0.25-4 mM) for SCE induction. All of the carboxylic acids tested also elevated SCEs, but only slightly. Formic acid and crotonic acid produced some SCE increase at a concentration of 10 mM, acetic acid at 5 and 10 mM and propionic acid at 2.5 mM. 2-Ethylhexanoic acid induced SCEs at a lower concentration range (0.63-2.5 mM) than the other acids. The positive concentrations of the first three carboxylic acids lowered the pH of the culture medium immediately after the treatment by 0.5-1.0 pH unit (lowest observed pH 6.53). The pH differences from the control cultures became smaller in measurements done 24 h and 48 h after the beginning of treatment. Propionic acid and 2-ethylhexanoic acid affected medium pH only slightly (maximum drop 0.2 pH units) at the concentrations that induced SCEs. The results lend support to the idea that the efficient SCE induction observed with the vinyl esters results from the formation of acetaldehyde, with carboxylic acids--with the possible exception of 2-ethylhexanoic acid--playing no significant role. The slight SCE induction obtained with the carboxylic acids cannot be explained by lowered pH alone.

Sister-chromatid exchanges induced by 1.3-butadiene and its epoxides in CHO cells.

Sister-chromatid exchanges (SCEs) were analyzed in CHO cells after pulse treatment with 1,3-butadiene, 3,4-epoxy-1-butene (monoepoxybutene) and 1,2:3,4-diepoxybutane (diepoxybutane). A weak dose effect was observed after exposure to 1,3-butadiene but only in the presence of S9 mix. Monoepoxybutene and diepoxybutane were highly effective in inducing SCEs at concentrations of 0.1-1 microM both in the presence and in the absence of S9 mix. At higher concentrations the response was more pronounced without S9 mix.

Styrene revisited--exposure assessment and risk estimation in reinforced plastics industry.

A survey performed in 32 workshops in reinforced plastics industry showed the mean TWA 8 h concentration of styrene in personal air to be 43 ppm (range 5-182 ppm) among laminators and 11 ppm (range 1-133 ppm) among other workers. The biological measurement of urinary mandelic acid + phenylglyoxylic acid showed mean values of 2.4 mmol/l among laminators without respirators and 1.3 mmol/l when respirators were used. No effects of work related exposure were detected in the cytogenetic parameters, chromosome aberrations, sister chromatid exchanges or micronuclei analyzed in peripheral blood lymphocytes. Grading of the exposure on the basis of lamination method, years of exposure, daily laminating time, air styrene concentration and urinary mandelic acid among laminators, neither revealed any dose dependency.

Induction of chromosome aberrations and sister-chromatid exchanges by caprolactam in vitro.

Caprolactam (CAP) induced chromosome aberrations in whole-blood cultures of human lymphocytes at 50 mM without metabolic activation (24-h treatment) and at 200 mM in the presence of rat liver S9 mix (1-h treatment). CAP also produced a dose-dependent increase in polyploid cells, the effect being statistically significant at 25 and 50 mM without S9 mix and at 100 and 200 mM with S9 mix. Without metabolic activation, there was an increase in hypodiploid cells at 50 mM and hyperdiploid cells at 12.5 mM. In Chinese hamster ovary cells, CAP produced a marginal elevation of sister-chromatid exchanges at 125 mM in the presence of S9 mix (4-h treatment). The results show that CAP is able to induce cytogenetic changes in vitro at very high toxic concentrations.

Cytogenetic effects of tobacco smoke exposure among involuntary smokers.

Tobacco smoke is highly genotoxic and produces chromosomal damage in several experimental systems. Active smokers have been shown to have an increased prevalence of somatic chromosome damage in their peripheral blood lymphocytes: this is seen in most cases as an increased sister-chromatid exchange (SCE) frequency and often also as increased structural chromosome aberrations (CAs). Among passive smokers, in association with exposure to environmental tobacco smoke, no such induction of chromosomal damage has been documented. In the present paper we report negative results on induction of chromosomal damage in 2 separate groups of intensive involuntary exposure to tobacco smoke, non-smoking restaurant personnel and newborn children of smoking mothers. While significant exposure in these groups is clearly seen in biochemical intake markers, e.g. cotinine and thiocyanate values in plasma, the conventional cytogenetic parameters, structural chromosome aberrations and sister-chromatid exchanges, are unable to detect the low exposures of involuntary smokers.

Chromosome damage induced by vinyl acetate through in vitro formation of acetaldehyde in human lymphocytes and Chinese hamster ovary cells.

A 48-h treatment with vinyl acetate (0.05-1 mM) induced a drastic increase in sister chromatid exchanges (SCEs) and (in first division cells) structural chromosome aberrations in cultured human lymphocytes. The effects were more pronounced in cultures of isolated lymphocytes than in whole-blood cultures. A distinct dose-dependent induction of SCEs similarly occurred in Chinese hamster ovary cells after a 24-h vinyl acetate treatment (0.125-1 mM). A pulse treatment of Chinese hamster ovary cells for 4 h also yielded a clear increase in SCEs, but at higher concentrations (0.3-5 mM). The presence of rat liver S9 mix enhanced the SCE-inducing effect of vinyl acetate in Chinese hamster ovary cells. Gas chromatographic analysis of human whole-blood lymphocyte cultures treated for 10 s-20 min with vinyl acetate (5.4 mM) revealed a rapid degradation of vinyl acetate and formation of acetaldehyde. During the 20-min observation period, no degradation of vinyl acetate or formation of acetaldehyde were observed in complete culture medium without blood, which suggested that the reaction was enzymatic. Acetaldehyde induced SCEs in human whole-blood lymphocyte cultures at concentrations (0.125-2 mM) comparable to those used for vinyl acetate. The results indicate that vinyl acetate induces chromosome damage in cell cultures through enzyme-mediated hydrolysis to acetaldehyde.