Micronucleus induction and FISH analysis in buccal cells and lymphocytes of nurses administering antineoplastic drugs

A genotoxic effect for antineoplastic drugs, in particular micronucleus induction, has been shown in several studies. The aim of our study was to assess genotoxic effects in nurses administering different mixtures of antineoplastic drugs in an oncology hospital by evaluating the frequency of micronuclei in exfoliated buccal cells and blood lymphocytes by use of the standard micronucleus (MN) test and by identifying, by means of FISH analysis with centromeric probes, the mechanism of micronucleus induction (clastogenic or aneugenic). The study group comprised 23 nurses, 10 of whom worked in the day-care hospital and 13 in the ward. Twenty healthy subjects were selected as controls. Pan-centromeric FISH analysis was performed on lymphocytes from a selected group of nurses (12/23 subjects) characterized by higher MN frequencies as observed by standard Giemsa staining. A significant increase of micronucleus frequency compared with controls was found in exfoliated buccal cells of both groups of nurses: day-care hospital nurses 0.92 versus 0.45 (p=0.034) and ward nurses 0.94 versus 0.45 (p=0.051). An increase, although not statistically significant, of mean MN frequency was also found by the MN standard test on lymphocytes of the day-care hospital nurses (10.9 versus 7.5; p=0.056), while no differences were found in ward nurses (8.15 versus 7.5; p=0.56). We found that the administration of antineoplastic drugs by nurses in ward units induced a higher frequency of FISH MN+ (43% of subjects) than in the day-care hospital (20%). This was associated with the micronucleus size percentage. This finding could be correlated with the different compositions of administered mixtures of antineoplastic drugs: in ward units the mixtures contained drugs, such as vinorelbine, that were absent in the mixtures administered in the day-care hospital. Our results show genetic damage induced by administration of antineoplastic drugs, particularly in exfoliated buccal cells. This result suggests the useful application of this non-invasive sampling to evaluate genotoxic effects of occupational exposure to mixtures of inhalable chemicals at low doses.     

Micronuclei assay: A potential biomonitoring protocol in occupational exposure studies

As micronuclei (MN) derive from chromosomal fragments and whole chromosomes lagging behind in anaphase, the MN assay can be used to show both clastogenic and aneugenic effects. This particularly concerns the use of MN as a biomarker of genotoxic exposure and effects, where differences in MN frequencies between exposed subjects and referents are expected to be small. The present paper reviews the use of the MN assay in biomonitoring of occupational exposure studies.     

Cytogenetic effects of hexavalent chromium in Bulgarian chromium platers

The aim of the present study was to evaluate the genotoxic effects of hexavalent chromium (Cr(VI)) in vivo in exposed Bulgarian chromium platers by using classical cytogenetic and molecular cytogenetic analyses of peripheral lymphocytes and exfoliated buccal cells. No significant difference was observed between the exposed workers and the controls with regard to the frequency of cells with chromosome aberrations (CAs) using conventional Giemsa staining and in the frequency of sister chromatid exchanges (SCEs). However, there was a significant increase in the number of cells with micronuclei (MN) in peripheral lymphocytes from chromium exposed workers as compared to the controls. In the buccal cells from these workers, this increase was even more pronounced. Cytosine arabinoside (AraC), an inhibitor of DNA synthesis and repair, was found to significantly increase the levels of MN in vitro in the lymphocytes of both groups. The increase was more expressed in the lymphocytes of chromium exposed workers. Both centromere positive (C(+)) as well as centromere negative (C(-)) MN were observed by the fluorescence in situ hybridization (FISH) technique in both of the cell types studied. No difference between C(+) and C(-) MN frequencies was found in the lymphocytes as well as in the buccal cells. Thus, Cr(VI) appears to have both clastogenic as well as aneugenic effects in humans.     

Genotoxic effects of occupational exposure to lead and cadmium

This study was designed to assess genotoxic damage in somatic cells of workers in a Polish battery plant after high-level occupational exposure to lead (Pb) and cadmium (Cd), by use of the following techniques: the micronucleus (MN) assay, combined with in situ fluorescence hybridization (FISH) with pan-centromeric probes, analysis of sister chromatid exchanges (SCEs), and the comet assay. Blood samples from 44 workers exposed to lead, 22 exposed to cadmium, and 52 unexposed persons were used for SCE and MN analysis with 5'-bromodeoxyuridine (BrdU) or cytokinesis block, respectively. In parallel, the comet assay was performed with blood samples from the same persons for detection of DNA damage, including single-strand breaks (SSB) and alkali-labile sites (ALS). In workers exposed mostly to lead, blood Pb concentrations ranged from 282 to 655 microg/l, while the range in the controls was from 17 to 180 microg/l. Cd concentration in lead-exposed workers fell in the same range as for the controls. In workers exposed mainly to cadmium, blood Cd levels varied from 5.4 to 30.8 microg/l, with respective values for controls within the range of 0.2-5.7 microg/l. Pb concentrations were similar as for the controls. The incidence of MN in peripheral lymphocytes from workers exposed to Pb and Cd was over twice as high as in the controls (P<0.01). Using a combination of conventional scoring of MN and FISH with pan-centromeric probes, we assessed that this increase may have been due to clastogenic as well as aneugenic effects. In Cd- and Pb-exposed workers, the frequency of SCEs as well as the incidence of leukocytes with DNA fragmentation in lymphocytes were slightly, but significantly increased ( P<0.05) as compared with controls. After a 3h incubation of the cells to allow for DNA repair, a clear decrease was found in the level of DNA damage in the controls as well as in the exposed workers. No significant influence of smoking on genotoxic damage could be detected in metal-exposed cohorts. Our findings indicate that lead and cadmium induce clastogenic as well as aneugenic effects in peripheral lymphocytes, indicating a potential health risk for working populations with significant exposures to these heavy metals.     

Chromosome and cytome analysis of the somatic cells of nuclear-chemical production workers with incorporated 239Pu

The analysis of plutonium production factors has been carried out by using two methodical approaches: assessment of chromosomal aberrations level in routine and G-banded metaphases and molecular-cytogenetic investigation of aneugenic/clastogenic damages in cytokinesis-block binuclear lymphocytes by FISH with centromere specific DNA probes. The obtaining data point out for the first time about both aneugenic and clastogenic influences of incorporated 239Pu with activity range from 0.37 to 6.95 kBq. Correlation analysis of chromosome aberrations with cytome abnormalities allowed finding significant connection between number parameters of metaphase and interphase approaches. The results of this study support the suggestion that aberrant chromosomes are involved preferable in aneugenic events. The FISH technique in binucleated cytokinesis-blocked lymphocytes allows extending of detecting spectrum of chromosome damages and glance of aneugenic mechanisms. Correlations between metaphase and interphase-FISH results point out a high sensitivity of FISH cytome assay, which could be used as an independent test for detection both clastogenic and aneugenic environment influences.     

Molecular biomonitoring of a population of nurses handling antineoplastic drugs

Many antineoplastic drugs have been found to have carcinogenic, mutagenic and teratogenic activity and so hospital personnel handling these substances are potentially exposed to health risk. Understanding this risk derived from protracted occupational exposure has great relevance even if the workers normally adopt individual and environmental protective measures. To address this question we have studied the presence of DNA and chromosome damage in a population of nurses employed in Italian oncology units and in matched controls. We used the comet assay to evidence the presence of DNA strand breaks, due to both acute and chronic exposure, and the micronucleus (MN) test, which is a measure of clastogenic and aneugenic events. Furthermore, since the individual response to the exogenous insults may be genetically determined, we studied the possible influence of single nucleotide polymorphism in XRCC1 and XRCC3 DNA repair genes on induced genetic damage. We also considered the effects of confounding factors like smoking, age and gender. The results indicated that the exposed subjects had significantly high levels of genetic damage. Age and gender were associated with increased values in MN, both in control and in exposed groups; the smoking habit affects MN frequency in controls, but not in workers. Furthermore we found that exposed subjects bearing at least one XRCC1 variant allele (399Gln) show higher values of MN. The present data provide the evidence to show that occupational exposure to antineoplastic drugs, even if in safety controlled conditions, represents a serious health risk. Furthermore we have shown that the presence of XRCC1 genetic polymorphism could contribute to increase the genetic damage in susceptible individuals who are occupationally exposed to dangerous substances.     

Induction of chromatid-type aberrations in peripheral lymphocytes of hospital workers exposed to very low doses of radiation

Radiological personnel represent workers exposed to low cumulative doses of radiation. As their surveillance is generally based on physical dosimetry, there is little or inconclusive information on biological effects due to radiation exposure at these doses. We aimed to explore the extent of chromosomal damage in circulating lymphocytes of hospital workers (technicians, nurses and physicians) chronically exposed to a very low level of radiation using conventional and molecular cytogenetic analyses (chromosome painting with chromosomes #2, #3 and #10 as probe cocktail). Compared with controls, exposed workers displayed a significant increase in the frequency of aberrant lymphocytes (1.26+/-0.11/100 cells versus 1.63+/-0.17/100 cells). In particular, exposed technicians showed significantly higher mean values than nurses or physicians (3.68+/-1.17/100 cells versus 1.36+/-0.18/100 cells and 1.36+/-0.09/100 cells, respectively). Interestingly, we found that the chromosomal damage was prevalently expressed as chromatid-type aberrations. Chromosome painting indicated that the frequency of chromosome rearrangements (CR; translocations and dicentrics pooled together) was approximately comparable between radiological workers and the control group. Moreover, we did not detect any significant difference due to radiation exposure when CR rates were considered separately for each of the three chromosomes in the probe cocktail.     

Cytogenetic monitoring of industrial radiographers using the micronucleus assay

Industrial radiography is the process of using either gamma-emitting radionuclide sources or X-ray machines to examine the safety of industrial materials. Industrial radiographers are among the radiation workers who receive the highest individual occupational radiation doses. To assess occupationally induced chromosomal damage, we performed the cytokinesis-block micronucleus (CBMN) assay in peripheral lymphocytes of 29 male industrial radiographers, exposed to ionizing radiation for 12.8 years+/-11.2, in comparison with 24 gender-, age-, and smoking habits-matched controls. The CBMN assay was combined with fluorescent in situ hybridization with a pan-centromeric DNA probe in 17 exposed subjects and 17 controls randomized from the initial populations. The mean cumulative equivalent dose, recorded by film dosimeters, was 67.2 mSv+/-49.8 over the past 5 years. The mean micronucleated binucleated cell rate (MCR) was significantly higher in the industrial radiographers than in the controls (10.7 per thousand +/-5.2 versus 6.6 per thousand +/-3.1, P=0.009); this difference was due to a significantly higher frequency of centromere-negative micronuclei (C-MN) in exposed subjects than in controls (8.5 per thousand +/-4.9 versus 2.2 per thousand +/-1.6, P<0.001). The two populations did not significantly differ in centromere-positive micronuclei (C+MN) frequency. These findings demonstrate a clastogenic effect in lymphocytes of industrial radiographers. MCR significantly positively correlated with age in the two groups. After correction for the age effect, MCR did not correlate with duration of occupational exposure. No correlation between radiation doses and MCR, C-MN, and C+MN frequencies was observed. In addition to physical dosimetry records, the enhanced chromosomal damage in lymphocytes of industrial radiographers emphasizes the importance of radiation safety programs.     

Cytogenetic effects in rotogravure printers exposed to toluene (and benzene).

Comparing 21 rotogravure printers exposed to toluene (medians: time-weighted air level 150 mg/m3, blood toluene 1.6 mumole/l) and 21 unexposed controls (median blood toluene less than or equal to 0.01 mumole/l) there was a significant increase in the frequency of micronuclei (MN) in pokeweed mitogen (PWM)-stimulated peripheral blood lymphocytes in the printers, as compared to the controls (2.8% vs. 1.5%; p = 0.03; all p adjusted for age and smoking). The frequency of small MN (size ratio MN/main nucleus less than or equal to 0.03) in PWM-stimulated lymphocytes was associated with the exposure (1% vs. 0.3%; p = 0.05). Furthermore, among the exposed subjects there was an association between blood toluene and small MN (0.17% per mumole/l; p = 0.0005). Small MN in phytohemagglutinin (PHA) cultures displayed no association with any exposure parameter. However, in the printers, an estimated cumulative exposure index was weakly correlated with the frequency of total MN in PHA-stimulated cells (0.00003% per mg/m3 x year; p = 0.07). Among the printers, chromosomal breaks in PHA-stimulated cells were associated with the duration of earlier benzene exposure (0.03% per year; p = 0.01). The results of this study strongly indicate that toluene causes a clastogenic effect on the B-cells even at low exposure levels. Further, earlier benzene exposure seems to have caused chromosomal breaks in T-cells.     

Chromosomal changes: induction, detection methods and applicability in human biomonitoring

The objective of this state of the art paper is to review the mechanisms of induction, the fate, the methodology, the sensitivity/specificity and predictivity of two major cytogenetic endpoints applied for genotoxicity studies and biomonitoring purposes: chromosome aberrations and micronuclei. Chromosomal aberrations (CAs) are changes in normal chromosome structure or number that can occur spontaneously or as a result of chemical/radiation treatment. Structural CAs in peripheral blood lymphocytes (PBLs), as assessed by the chromosome aberration (CA) assay, have been used for over 30 years in occupational and environmental settings as a biomarker of early effects of genotoxic carcinogens. A high frequency of structural CAs in lymphocytes (reporter tissue) is predictive of increased cancer risk, irrespective of the cause of the initial CA increase. Micronuclei (MN) are small, extranuclear bodies that arise in dividing cells from acentric chromosome/chromatid fragments or whole chromosomes/chromatids that lag behind in anaphase and are not included in the daughter nuclei in telophase. The cytokinesis-block micronucleus (CBMN) assay is the most extensively used method for measuring MN in human lymphocytes, and can be considered as a "cytome" assay covering cell proliferation, cell death and chromosomal changes. The key advantages of the CBMN assay lie in its ability to detect both clastogenic and aneugenic events and to identify cells which divided once in culture. Evaluation of the mechanistic origin of individual MN by centromere and kinetochore identification contributes to the high sensitivity of the method. A number of findings support the hypothesis of a predictive association between the frequency of MN in cytokinesis-blocked lymphocytes and cancer development. Recent advances in fluorescence in situ hybridization (FISH) and microarray technologies are modifying the nature of cytogenetics, allowing chromosome and gene identification on metaphase as well as in interphase. Automated scoring by flow cytometry and/or image analysis will enhance their applicability.     

Use of C-banding for identifying radiation induced micronuclei

Differentiation of micronuclei (MN) caused by ionizing radiation from those caused by chemicals is a crucial step for managing treatment of individuals exposed to radiation. MN in binucleated lymphocytes in peripheral blood are widely used as biomarkers for estimating dose of radiation, but they are not specific for ionizing radiation. MN induced by ionizing radiation originate predominantly as a result of chromosome breaks (clastogenic action), whereas MN caused by chemical agents are derived from the loss of entire chromosomes (aneugenic action). C-banding highlights centromeres, which might make it possible to distinguish radiation induced MN, i.e., as a byproduct of acentric fragments, from those caused by the loss of entire chromosomes. To test the use of C-banding for identifying radiation induced MN, a blood sample from a healthy donor was irradiated with 3 Gy of Co-60 gamma rays and cultured. Cells were harvested and dropped onto slides, divided into a group stained directly with Giemsa and another processed for C banding, then stained with Giemsa. The frequency of MN in 500 binucleated cells was scored for each method. In preparations stained with Giemsa directly, the MN appeared as uniformly stained structures, whereas after C banding, some MN exhibited darker regions corresponding to centromeres that indicated that they were not derived from acentric fragments. The C-banding technique enables differentiation of MN from acentric chromosomal material. This distinction is useful for improving the specificity of the MN assay as a biomarker for ionizing radiation.     

Results of cytogenetic testing of workers exposed to ethylene oxide

The present work was undertaken to test cytogenetically workers exposed to Ethylene oxide (EO) aiming at detecting possible adverse effects of this agent to man. In the period 1983-1984, female workers of the Laboratory of Toxicology and the Production laboratory of ethylene oxide production in a chemical plant, and female workers in a sterilization centers in a medical facilities, were repeatedly examined. In 1984, also workers in ethylene oxide production in a chemical plant were tested. For each exposed group a control group was simultaneously examined, using cytogenetic analysis of peripheral blood lymphocytes. General examination of the health condition of exposed workers were organized in the framework of preventive examinations. The exposure level to ethylene oxide in the working environment was simultaneously monitored. The results have revealed an increase in chromosomal aberrations in lymphocytes of persons exposed professionally to EO at the given exposure levels. Smoking was associated with increased frequency of chromosomal aberrations in exposed workers; the difference as compared to non-smokers was however insignificant. By contrast, difference in chromosomal aberration frequency between smokers and non-smokers was significant in the control group.     

Study of the cytogenetic effects of occupational exposure to pesticides on sanitation workers in Belo Horizonte, Brazil

Sanitation workers handling pesticides in the control of disease vectors constitute an occupationally exposed population to genotoxic substances. The aim of the present study was to investigate the relation between the occupational exposure to various pesticides and the presence of cytogenetic damage. Fifty-nine men were selected (29 sanitation workers and 30 control individuals) with ages varying between 18-57 years who lived and worked in the same area in Belo Horizonte (Brazil). The following parameters were determined for all individuals using the cytokinesis-block micronucleus (MN) assay in peripheral blood lymphocytes: MN/1000 binucleated cells (BC), BC with MN (BCMN)/1000 BC, nucleoplasmic bridges (NB)/1000 BC, apoptotic and necrotic cells/500 cells and nuclear division index. The analysis of covariance showed significantly higher (p < 0.05) mean frequencies of MN (15.81 +/- 1.31 vs 4.71 +/- 0.42), BCMN (15.10 +/- 1.22 vs 4.62 +/- 0.44), NB (4.59 +/- 0.76 vs 1.00 +/- 0.34), and necrotic cells (12.07 +/- 1.45 vs 5.17 +/- 0.70) in the exposed group when compared to the control group. There was no significant difference in the apoptotic cell frequency between the two groups, while the nuclear division index was significantly lower (1.49 +/- 0.02 vs 1.61 +/- 0.02) in the control group. Neither the time of exposure nor the smoking or alcohol drinking habit influenced the cytogenetic parameters examined. According to these results, occupational exposure to pesticides induced genotoxic and cytotoxic effects in sanitation workers.     

Cytogenetic biomonitoring of inhabitants of a large uranium mineralization area: the municipalities of Monte Alegre, Prainha, and Alenquer, in the State of Pará, Brazil

Uranium is a natural radioactive metallic element; its effect on the organism is cumulative, and chronic exposure to this element can induce carcinogenesis. Three cities of the Amazon region—Monte Alegre, Prainha, and Alenquer—in North Brazil, are located in one of the largest uranium mineralization areas of the world. Radon is a radioactive gas, part of uranium decay series and readily diffuses through rock. In Monte Alegre, most of the houses are built of rocks removed from the Earth’s crust in the forest, where the uranium reserves lie. The objective of the present work is to determine the presence or absence of genotoxicity and risk of carcinogenesis induced by natural exposure to uranium and radon in the populations of these three cities. The frequency of micronuclei (MN) and chromosomal aberrations (CA) showed no statistically significant differences between the control population and the three study populations (P > 0.05). MN was also analyzed using the fluorescence in situ hybridization (FISH) technique, with a centromere-specific probe. No clastogenic and/or aneugenic effects were found in the populations. Using FISH analysis, other carcinogenesis biomarkers were analyzed, but neither the presence of the IGH/BCL2 translocation nor an amplification of the MYC gene and 22q21 region was detected. Clastogenicity and DNA damage were also not found in the populations analyzed using the alkaline comet assay. The mitotic index showed no cytotoxicity in the analyzed individuals’ lymphocytes. Once we do not have data concerning radiation doses from other sources, such as cosmic rays, potassium, thorium, or anthropogenic sources, it is hard to determine if uranium emissions in this geographic region where our study population lives are too low to cause significant DNA damage. Regardless, genetic analyses suggest that the radiation in our study area is not high enough to induce DNA alterations or to interfere with mitotic apparatus formation. It is also possible that damages caused by radiation doses undergo cellular repair.     

Cytogenetic effects in children and mothers exposed to air pollution assessed by the frequency of micronuclei and fluorescence in situ hybridization (FISH): a family pilot study in the Czech Republic

A family pilot study was conducted in the Czech Republic to test the hypothesis that exposure to air pollution with particulate matter (PM) in children results in detectable effects indicated by a number of biomarkers of exposure and early effects. The frequency of micronuclei (MN) in peripheral blood lymphocytes (PBLs) was analysed to assess the cytogenetic effects in children and mothers living in two different areas. From each area two groups of children from a total of 24 families (mean age: 6.0+/-0.6 and 9.0+/-1.2 years) in a total of 47 children and 19 mothers (mean age: 33.6+/-3.9 years) participated. Chromosome aberrations determined with fluorescence in situ hybridization (FISH) painting for chromosomes #1 and #4 were analysed in 39 children and 20 parents. Teplice, a mining district, in Northern Bohemia was selected for the analyses of the effects in a population exposed to high levels of air pollution, especially during winter, and compared with a population from the rural area of Prachatice in Southern Bohemia. Significant higher frequencies of MN were found in the younger children living in the Teplice area as compared with those living in the Prachatice area (7.0+/-2.3 per thousand versus 4.9+/-2.0 per thousand, p=0.04). Higher levels of MN were also measured in the older children and the mothers from the Teplice area (9.2+/-3.7 per thousand versus 6.6+/-4.4 per thousand) and (12.6+/-3.4 per thousand versus 10.1+/-4.0 per thousand). The increased MN frequency may be associated with elevated carcinogenic polycyclic aromatic hydrocarbons (c-PAHs) concentration of the PM(2.5) measured in the ambient Teplice air, but other factors like genotoxic compounds from the diet or protective effect of micronutrients, which was not addressed in this pilot study, may also differ between the two areas. MN frequencies were found to increase with age in children. Lower MN frequency was found in boys as compared to girls. The result of the FISH analyses showed a low number of individuals with detectable levels of aberrations and no significant increases in genomic frequency of stable chromosome exchanges (F(G)/100) were found in children or parents from the Teplice area in comparison with those from the Prachatice area. The family pilot study indicates that MN is a valuable and sensitive biomarker for early biological effect in children and adults living in two different areas characterised with significant exposure differences in c-PAHs concentrations during winter.     

Chromosomal changes induced in mouse bone marrow cells following six weeks inhalation of cyclohexanol

The effects of low doses of cyclohexanol exposure were studied in mouse bone marrow cells including chromosome aberrations (CA), micronucleus (MN) and sister chromatid exchanges (SCE) as biomarkers. Capillaries with a tested agent that was evaporated continuously were placed in an experimental chamber for six weeks. No clastogenic and/or aneugenic effect of CA and MN induction was observed. A significant elevation of induced damage was achieved in the SCE study (p < 0.001) that has confirmed the early exposure of cyclohexanol to mice.     

Genotoxic effects of styrene-7,8-oxide in human white blood cells: comet assay in relation to the induction of sister-chromatid exchanges and micronuclei

Styrene is used in the production of plastics, resins and rubber. The highest human exposures to styrene take place by inhalation during the production of fiberglass reinforced plastics. Styrene is metabolized mainly in the liver to styrene-7,8-oxide (SO), its principal in vivo mutagenic metabolite. In this study, human peripheral white blood cells were exposed to several SO concentrations (10-200 microM) in order to evaluate its genotoxic properties by means of comet assay, sister-chromatid exchanges (SCE) and cytokinesis-blocked micronucleus (MN) test, in addition to determine its clastogenic or aneugenic properties by combining MN with fluorescence in situ hybridization (FISH) procedures. Our results show that SO induces DNA damage, SCE and MN in human leukocytes in vitro at concentrations above 50 microM, and that there is a strong relationship between DNA damage, as measured by the comet assay, and cytogenetic damage induced by SO at the doses employed. SO shows preferentially a clastogenic activity and produces a cytostatic effect at high doses, reflected by the significant decrease of the calculated proliferation indices. A good dose-effect relationship is obtained in the three tests performed at the concentration range assayed.     

Genotoxic effects of butadiene in mouse lung cells detected by an ex vivo micronucleus test

Lung fibroblasts from BD-exposed mice have been analysed for the occurrence of micronuclei. Primary cultures set up 24h after the end of exposure were treated with cytochalasin B and micronuclei scored in binucleate cells. A three-fold statistically significant increase of micronucleated cells was detected after exposure to 500ppm, the lowest tested concentration. A linear dose effect relationship was observed between 500 and 1300ppm. Immunofluorescent staining of kinetochore proteins was applied to distinguish between acentric micronuclei produced by chromosome breaks and micronuclei containing a centromeric region, most likely induced by chromosome loss. A statistically significant increase of both types of MN in 1300ppm-exposed females and a significant increase in centromeric MN in 500ppm-exposed males were detected. These data demonstrate that an intermediate of BD metabolism with a potential for clastogenic and aneugenic effects is active in lung cells after inhalation exposure. These effects can play a role in the initiation and promotion of BD-induced lung tumours.     

Correlation of human lymphocyte SCE frequency with smoking history

The relationship between the level of occupational exposure to epichlorohydrin (ECHH) and the clastogenic effect was studied on a group of 33 workers. The effect of ECHH was assessed by differences in the frequency of chromosome aberrations in peripheral blood lymphocytes in ECHH-exposed and control groups. In the group exposed to the average ECHH concentration, 0.384 mg X m-3, during the last 6 months, the cytogenetic analysis revealed 2.00 +/- 0.23% AC (aberrant cells) (0.0203 B/C, breaks per cell) as compared with 1.68 +/- 0.23% AC (0.0172 B/C) in the matching controls. These results indicate that an average concentration lower than 0.40 mg X m-3 ECHH in the working atmosphere has no significant clastogenic effect on human peripheral lymphocytes.     

Clastogenic effect of pesticides in peripheral lymphocytes of cotton-field workers.

We studied clastogenic effects in peripheral lymphocytes of cotton-field workers who were exposed to different pesticides. All the cells were grown in RPMI 1640 medium for 48 and 72 h. The type of aberrations observed in the exposed group are gaps, breaks, dicentrics, exchanges, rings and polyploidy. The frequency of total chromosomal aberrations increased significantly in male pesticide applicators when compared to controls. A significant decrease in mitotic index was observed in the exposed group as compared to the control group. The 48-h cultures showed high incidence of chromosomal aberrations and low mitotic index when compared to 72-h cultures. The difference in chromosomal aberrations between 48- and 72-h cultures was not significant. 24 out of 26 individuals showed ill health effects such as severe giddiness and nervous disorders.