The micronucleus assay in exfoliated buccal cells: application to occupational exposure to polycyclic aromatic hydrocarbons

Is micronucleus assay in oral cells suitable biomarker for evaluating the risk of carcinogenesis in gas station attendants? A systematic review

This study aimed to evaluate all studies which used the micronucleus assay using oral cells in the attempt to understand whether such technique is efficient in evaluating genotoxicity in gas station attendants. Full manuscripts from 16 studies were carefully selected by the authors. Our results demonstrate that continuous exposure to derivatives of petroleum may lead to genotoxic effects since all studies demonstrated positive findings (16 out of 16) and 11 of them had a strong or moderate final rating. In summary, our results reveal that gas station attendants are occupationally exposed to genotoxic agents and that the micronucleus assay in oral mucosa is indeed an effective method to evaluate genotoxicity in this specific case. Such findings are very important for protecting these professionals who are continuously exposed to chemicals for long periods.

Household cooking oil type and risk of oral micronucleus frequency in Chinese nonsmokers

Household animal fat has been linked to increased incidence of cancers compared with vegetable fat. However, few epidemiological studies have associated these two cooking oil types with precancerous genotoxic effects, such as occurrence of micronuclei (MN). This study aimed to explore the association between oral MN frequency and household cooking oil type and whether the association can be attributed to polycyclic aromatic hydrocarbons (PAHs). We collected information about individual cooking oil use, measured genotoxic effects by MN tests and urinary PAHs metabolites (OHPAHs) in 245 nonsmokers. The associations between household cooking oil type and MN frequency and OHPAHs were analyzed using generalized linear models (GLMs) and logistic regression models, evaluating odds ratios and coefficient (95% confidence intervals) (ORs, 95% Cls; β, 95% Cls). The odds of animal fat consumers, rather than vegetable fat consumers, was positively associated with higher MN frequency (OR = 1.94, P < 0.05). The associations were discovered in participants only using kitchen ventilation (OR = 2.04, P < 0.05). Animal fat consumers had higher total OHPAHs than vegetable fat consumers (1.58 ± 0.22 mg/mol, Cr vs 1.20 ± 0.12 mg/mol, Cr; P = 0.028). Significant correlations were observed between total OHPAHs quartiles and increased MN frequency (β = 0.38, P-trend = 0.026). After stratifying by household cooking oil type, sensitivity analyses showed that the positive association between total OHPAHs quartiles and increased MN frequency was only observed in animal fat consumers (β = 0.61, P-trend = 0.030). In conclusion, usage of household animal fat was associated with an increased odds of oral MN frequency in Chinese nonsmokers and the odds correlated with increased PAHs exposure. This finding supplemented evidence associating cooking oil type with genotoxic effects and explained its association with PAHs exposure.

In Vivo Evaluation of Micronucleus Frequencies in Buccal Mucosal Cells of Orthodontic Patients with and Without Fluoride Use

Introduction:

Fluoride agents to prevent white spot lesions are used often during orthodontic treatment. The beneficial effects of fluoride, when consumed within permissible limits on dental structures, are well known. Their implications on underlying biological tissues, however, are unknown. Mouthwashes and dentifrices with fluorides are associated with metal ion release into the mouth with possible cell genotoxicity. Since these cariostatic agents are frequently used during orthodontic therapy, a deeper understanding of the effects of fluoride on oral tissues was considered necessary.

Methodology:

Three groups of patients (30 each)—group 1 (untreated controls), group 2 (non-fluoridated), and group 3 (Fluoridated) were analyzed. Patients in groups 2 and 3 were bonded with the same bracket prescription and treated with similar archwire sequences. Buccal mucosal cells at 4 specific time periods (before treatment, 1 week, 30 days, and 6 months) were collected, using a wooden tongue depressor, and assessed for any nuclear abnormalities. Comparisons of changes were made with an untreated control group and also between the non-fluoridated and fluoridated groups. Relevant conclusions were drawn after analysis of the results.

Results:

Greater number of nuclei were observed at the 30-day time interval in the fluoridated group, which was statistically significant at P < .001.

Conclusion:

Use of fluoridated oral hygiene products in patients undergoing fixed orthodontic treatment with NiTi archwires could increase the risk of micronuclei formation in buccal mucosal cells.

Penalized negative binomial models for modeling an overdispersed count outcome with a high-dimensional predictor space: Application predicting micronuclei frequency

Chromosomal aberrations, such as micronuclei (MN), have served as biomarkers of genotoxic exposure and cancer risk. Guidelines for the process of scoring MN have been presented by the HUman MicroNucleus (HUMN) project. However, these guidelines were developed for assay performance but do not address how to statistically analyze the data generated by the assay. This has led to the application of various statistical methods that may render different interpretations and conclusions. By combining MN with data from other high-throughput genomic technologies such as gene expression microarray data, we may elucidate molecular features involved in micronucleation. Traditional methods that can model discrete (synonymously, count) data, such as MN frequency, require that the number of explanatory variables (P) is less than the number of samples (N). Due to this limitation, penalized models have been developed to enable model fitting for such over-parameterized datasets. Because penalized models in the discrete response setting are lacking, particularly when the count outcome is over-dispersed, herein we present our penalized negative binomial regression model that can be fit when P > N. Using simulation studies we demonstrate the performance of our method in comparison to commonly used penalized Poisson models when the outcome is over-dispersed and applied it to MN frequency and gene expression data collected as part of the Norwegian Mother and Child Cohort Study. Our countgmifs R package is available for download from the Comprehensive R Archive Network and can be applied to datasets having a discrete outcome that is either Poisson or negative binomial distributed and a high-dimensional covariate space.

Assessment of DNA damage in welders using comet and micronucleus assays

Welding technology is widely used in pressurized containers, thermal power plants, refineries, chemical facilities and steel structures. Welders are exposed to a number of hazardous compounds such as ultraviolet (UV) radiation, electromagnetic fields, toxic metals and polycyclic aromatic hydrocarbons (PAHs). In the present study, 48 welders and an equal number of control subjects were evaluated for DNA damage in the whole blood and isolated lymphocytes using the comet assay. The genotoxic damage in buccal epithelial cells of subjects was determined by micronucleus (MN) assay. Metal(loids) such as Cr, Mn, Ni, Cu, As, Cd and Pb levels in blood samples were evaluated by using Inductively Coupled Plasma-Mass Spectrometer (ICP-MS). Results of this study showed that DNA damage in blood, isolated lymphocytes, and buccal epithelial cells were significantly higher in workers compared to the controls. Also, these workers had remarkably higher blood Cr, Cu, Cd, Ni and Pb levels. These results showed that occupational exposure to welding fumes may cause genotoxic damage that can lead to important health problems in the workers. More extensive epidemiological studies should be performed that enable the assessment of health risk in welding industry.

Genotoxic Effects of Exposure to Gasoline Fumes on Petrol Pump Workers

Background:

Petrol pump workers are occupationally exposed to gasoline and its fumes consisting of several mutagenic chemicals.

Objective:

To evaluate the genotoxic effects of exposure to gasoline fumes on petrol pump workers.

Methods:

The study groups included 70 petrol pump workers (exposed group) and 70 healthy age-matched individuals with no known exposure (comparison group). Buccal micronucleus cytome assay (BMCyt) was performed to check the genotoxicity caused due to inhalation of gasoline fumes.

Results:

The frequencies of micronucleated cells, nuclear bud, condensed chromatin cells, karyorrhectic cells, pyknotic cells, and karyolytic cells were significantly higher in the exposed workers compared to the comparison group.

Conclusion:

Exposure to gasoline fumes is associated with increased frequency of cell abnormalities. This may lead to various health consequences including cancer in those occupationally exposed to gasoline fumes.

Micronuclei and other nuclear anomalies in buccal epithelial cells of children with chronic kidney disease

The objective of this study was to reveal the likely genomic instability in children with chronic kidney disease (CKD) using micronucleus (MN) assay on buccal epithelial cells (BEC). We investigated the frequencies of micronuclei and other nuclear anomalies, such as nuclear buds, binucleated cells, condensed chromatin, and karyorrhectic and pyknotic cells in BEC. Children with CKD were grouped as follows: children in the pre-dialysis (PreD) stage (N=17), children on regular haemodialysis (HD) (N=14), and children who have undergone transplantation (Tx) (N=17). As a control group, twenty age- and gender-matched healthy children were selected. The MN frequency in BEC of all groups of children with CKD was significantly elevated (5- to 7-fold) as compared to the control group (p<0.001). In contrast, the frequencies of nuclear buds were not significantly higher in the study groups compared to the control group. The frequencies of binucleated cells and condensed chromatin cells were significantly higher in all subgroups of children with CKD relative to the control group (p<0.001). Our results show that the BEC of pediatric PreD, HD, and Tx patients with CKD display increased cytogenetic, cytokinetic, and cytotoxic effects. They also point to the sensitivity and usefulness of the BEC MN assay in the assessment of genetic susceptibility of patients with CKD.

Evaluation of genetic damage in tobacco and arsenic exposed population of Southern Assam, India using buccal cytome assay and comet assay

Ground water is the principal source of drinking water in Assam. Ground water contamination of arsenic in drinking water is a great concern for human health and considered as a human carcinogen. The present cytogenetic biomonitoring study was undertaken to investigate the genotoxic effects associated with people of southern Assam consuming arsenic contaminated water and chewing tobacco. Employing the buccal cytome assay, exfoliated cells were analyzed in 138 individuals of age range 22-42 years and divided into four groups. Group I (n=54) are participants residing in localities where ground water contains arsenic concentration below the permissible limit (<10μg/l) and without any tobacco chewing history. Group II (n=32) participants from the same area but they are tobacco chewers. Group III (n=24) participants from localities where significantly high arsenic contamination in ground water were observed. Whereas the Group IV (n=28) consists of participants from the arsenic contaminated area and also tobacco chewers. Body mass index (BMI) in all the groups are found to be nearly same and in normal range. Statistically significant (P<0.001) increase in genotoxic, cell death parameters and cell proliferation biomarkers were observed in the Group IV compared to other groups. In the comet assay, percent of tail DNA gradually increases among the groups and has statistical significance. Spearman correlation revealed strong positive correlation between the arsenic exposed peoples and the binucleated cells (r=0.4763; P<0.001). Amount of chewing tobacco had significant positive correlation with micronucleus frequency (r=0.268; P<0.05) and karyolitic cells (r=0.217; P<0.05) and also in the percentage of tail DNA (r=0.5532, P<0.001). A statistically significant increase in glucose content and decrease in hemoglobin content as well as acetylcholine esterase in the blood of exposed individuals was observed. Our preliminary study indicate that population exposed to arsenic through drinking water may become more susceptible towards chewing tobacco induced nuclear damage as evaluated by buccal cytome assay and comet assay.

Noninvasive effects measurements for air pollution human studies: methods, analysis, and implications

Human exposure studies, compared with cell and animal models, are heavily relied upon to study the associations between health effects in humans and air pollutant inhalation. Human studies vary in exposure methodology, with some work conducted in controlled settings, whereas other studies are conducted in ambient environments. Human studies can also vary in the health metrics explored, as there exists a myriad of health effect end points commonly measured. In this review, we compiled mini reviews of the most commonly used noninvasive health effect end points that are suitable for panel studies of air pollution, broken into cardiovascular end points, respiratory end points, and biomarkers of effect from biological specimens. Pertinent information regarding each health end point and the suggested methods for mobile collection in the field are assessed. In addition, the clinical implications for each health end point are summarized, along with the factors identified that can modify each measurement. Finally, the important research findings regarding each health end point and air pollutant exposures were reviewed. It appeared that most of the adverse health effects end points explored were found to positively correlate with pollutant levels, although differences in study design, pollutants measured, and study population were found to influence the magnitude of these effects. Thus, this review is intended to act as a guide for researchers interested in conducting human exposure studies of air pollutants while in the field, although there can be a wider application for using these end points in many epidemiological study designs.

Increased cytogenetic abnormalities in exfoliated oral mucosal cells of South Indian foundry workers

Biomonitoring offers a valuable tool to estimate the genetic risk as of exposure to genotoxic agents. Here, we intend to assess the potential cytogenetic damage related with occupational exposure to polycyclic aromatic hydrocarbons by evaluating the genetic damages in exfoliated buccal epithelial cells of foundry workers via counting micronucleus (MNs) and other nuclear abnormalities (NAs). This was a cross-sectional study and all study subjects were male . Exfoliated buccal mucosal cells were obtained from 100 subjects involved in either foundry molding or melting processes, and 100 controls matched for sex, age, and smoking from the area of Coimbatore city, Southern India. For each individual, 2000 exfoliated buccal cells were analyzed. Significantly, there was a higher frequency of MN in the exposed workers than in the controls (P < 0.05). Smoking was associated with the increased frequencies of micronuclei and NAs in the buccal epithelium of both the control and the exposed groups. Smoking represented significant factors in terms of increasing the production of MN when the control and the exposed groups were compared (P < 0.05). The results specify that buccal cells of foundry workers display increased levels of genotoxicity and these biomarker responses may be related to the increased cancer risk. These results conclude that the studied individuals are at a risk group and they require periodical biological monitoring and proper care which is essential for them.

Genetic damage in coal miners evaluated by buccal micronucleus cytome assay

During coal mining activities, large quantities of coal dust, ashes, polycyclic aromatic hydrocarbons and metals are released into the environment. This complex mixture presents one of the most important occupational hazards for health of workers. The aim of the present study was to evaluate the genetic damage together with the presence of inorganic elements, in an exposed workers population to coal mining residues of Guajira-Colombia. Thus, 100 exposed workers and 100 non-exposed control individuals were included in this study. To determine genetic damage we assessed the micronucleus (MN) frequencies and nuclear buds in buccal mucosa samples (BMCyt) assay, which were significantly higher in the exposed group than non-exposed control group. In addition, karyorrhectic and karyolytic cells were also significantly higher in the exposed group (cell death). No significant difference was observed between the exposed groups engaged in different mining activities. No correlation between age, alcohol consumption, time of service and MN assay data were found in this study. However, the content of inorganic elements in blood samples analyzed by a Particle-induced X-ray emission technique (PIXE) showed higher values of silicon (Si) and aluminum (Al) in the exposed group. In this study we discuss the possibility of DNA damage observed in the mine workers cells be a consequence of oxidative damage.

A comparison of the human buccal cell assay and the pollen abortion assay in assessing genotoxicity in an urban-rural gradient

Air pollution is exacerbated near heavy traffic roads in cities. Air pollution concentration and composition vary by region and depend on urban-rural gradients. The aim of this study was to evaluate the distribution of air pollution in areas of varying population densities and to compare plant biomonitoring with an established biomarker of human exposure to traffic-related air pollution in children. The areas of study were selected near a major street in 3 different regions. Areas A, B and C represent high, intermediate and low population densities, respectively. Micronucleus assay, an established biomarker of human exposure, was performed in children from these areas. For a plant biomonitoring assay, the pollen abortion assay was performed on Bauhinia variegata in these areas. NO₂ and O₃ concentrations were determined by passive sampling. We report here that the pollen abortion frequency in Bauhinia variegata is correlated with NO₂ concentration (P = 0.004) and is strongly associated with vehicular flow and population density in the studied areas. Micronuclei frequency in buccal cells of children was higher in the regions with more degree of urbanization (P < 0.001) following the same pattern of O₃ concentrations (P = 0.030). In conclusion, our results demonstrate that high concentrations of air pollutants in Porto Alegre are related to both human and plant genotoxicity. Areas with different concentration of pollutants demonstrated to have an urbanization gradient dependent pattern which also reflected on genotoxic damage among these areas.

Comparative Study of Genotoxicity in Different Tobacco Related Habits using Micronucleus Assay in Exfoliated Buccal Epithelial Cells

BACKGROUND

Oral cancer is one of the most debilitating diseases afflicting mankind. Consumption of tobacco in various forms constitutes one of the most important etiological factors in initiation of oral cancer. When the focus of today's research is to determine early genotoxic changes in human cells, micronucleus (MN) assay provides a simple, yet reliable indicator of genotoxic damage.

AIMS AND OBJECTIVES

To identify and quantify micronuclei in the exfoliated cells of oral mucosa in individuals with different tobacco related habits and control group, to compare the genotoxicity of different tobacco related habits between each group and also with that of control group.

PATIENTS AND METHODS

In the present study buccal smears of 135 individuals with different tobacco related habits & buccal smears of 45 age and sex matched controls were obtained, stained using Giemsa stain and then observed under 100X magnification in order to identify and quantify micronuclei in the exfoliated cells of oral mucosa.

RESULTS

The mean Micronucleus (MN) count in individuals having smoking habit were 3.11 while the count was 0.50, 2.13, and 1.67 in normal control, smoking with beetle quid and smokeless tobacco habit respectively. MN count in smokers group was 2.6 times more compared to normal controls. MN count was more even in other groups when compared to normal control but to a lesser extent.

CONCLUSION

From our study we concluded that tobacco in any form is genotoxic especially smokers are of higher risk and micronucleus assay can be used as a simple yet reliable marker for genotoxic evaluation.

DNA damage in buccal mucosa cells of pre-school children exposed to high levels of urban air pollutants

Air pollution has been recognized as a human carcinogen. Children living in urban areas are a high-risk group, because genetic damage occurring early in life is considered able to increase the risk of carcinogenesis in adulthood. This study aimed to investigate micronuclei (MN) frequency, as a biomarker of DNA damage, in exfoliated buccal cells of pre-school children living in a town with high levels of air pollution. A sample of healthy 3-6-year-old children living in Brescia, Northern Italy, was investigated. A sample of the children's buccal mucosa cells was collected during the winter months in 2012 and 2013. DNA damage was investigated using the MN test. Children's exposure to urban air pollution was evaluated by means of a questionnaire filled in by their parents that included items on various possible sources of indoor and outdoor pollution, and the concentration of fine particulate matter (PM10, PM2.5) and NO2 in the 1-3 weeks preceding biological sample collection. 181 children (mean age ± SD: 4.3 ± 0.9 years) were investigated. The mean ± SD MN frequency was 0.29 ± 0.13%. A weak, though statistically significant, association of MN with concentration of air pollutants (PM10, PM2.5 and NO2) was found, whereas no association was apparent between MN frequency and the indoor and outdoor exposure variables investigated via the questionnaire. This study showed a high MN frequency in children living in a town with heavy air pollution in winter, higher than usually found among children living in areas with low or medium-high levels of air pollution.

Micronucleus assay assessment of possible genotoxic effects in patients treated with titanium alloy endosseous implants or miniplates

The use of titanium and its alloys (Ti-6Al-4V) for oral surgery has increased dramatically in recent years. Ti is a stable biocompatible metal suitable for oral applications and it has been used for endosseous subperiosteal implants and miniplate fixation for more than 25 years. Dental implants are typically made of Ti or Ti alloys. The alloys are potentially toxic due to release of vanadium and aluminum. We tested the possible genotoxicity of Ti alloy endosseous implants and miniplates on the oral mucosal tissues of two groups of patients: 17 patients receiving Ti miniplate and screw fixation, and 37 endosseous dental implant placement patients. Preoperative and postoperative mucogingival cell samples were collected. Genotoxicity was assessed by the micronucleus assay (MN). There were slight but not statistically significant increases in the frequencies of MN (p=0.087 and p=0.047) post-operation in both groups. In summary, neither of the applications showed genotoxicity in the oral epithelial cells of patients.

The HUMNxl scoring criteria for different cell types and nuclear anomalies in the buccal micronucleus cytome assay - an update and expanded photogallery

The buccal micronucleus cytome assay is a minimally invasive cytological and interphase cytogenetic technique for measuring DNA damage and cell death biomarkers in the oral epithelium. In this report we provide an updated and more comprehensive version of the cellular and nuclear scoring criteria used in the assay accompanied with a photogallery of the various cell types and nuclear anomalies. These detailed scoring criteria complement previous published protocols of this assay and form the basis for guiding intra- and inter-laboratory slide scoring comparisons. The scoring criteria update described in this paper is the outcome of ongoing efforts of the HUMN and HUMNxl projects (www.humn.org) to standardize the application of micronucleus assay for use in human biomonitoring and to update procedures as knowledge on mechanisms and technical capability improvements.

Toxicogenetic monitoring in urban cities exposed to different airborne contaminants

Microparticles found in the air may be associated with organic matter that contains several compounds, such as Polycyclic Aromatic Hydrocarbons (PAHs) and nitro-PAHs, and may pose a significant risk to human health, possibly leading to DNA mutations and cancers. This study associated genotoxicity assays for evaluating human exposure with the atmospheric air of two urban areas in southern Brazil, that received different atmospheric contributions. Site 1 was under urban-industrial influence and the other was a non-industrial reference, Site 2. Organic extracts from the airborne particulate matter were tested for mutagenicity via the Salmonella/microsome assay and analyzed for PAH composition. Cells samples of people residing in these two cities were evaluated using the comet and micronucleus assay (MN).Concentrations of the individual PAHs ranged from 0.01 ng/m(3) (benzo[a]anthracene) to 5.08 ng/m(3) (benzo[ghi]perylene). As to mutagenicity analysis of airborne, Site 1 presented all the mutagenic responses, which varied from 3.2±1.22 rev/m(3) (TA98 no S9) to 32.6±2.05 rev/m(3) (TA98, S9), while Site 2 ranged from negative to minimal responses. Site 1 presented a high quantity of nitro and amino derivatives of PAHs, and peaked at 56.0±3.68 rev/μg (YG1024 strain). The two groups presented very low DNA damage levels without intergroup difference. Although Site 1 presented high mutagenic responses in the air samples, high PAH levels, healthy people exposed to this environment did not show significative damage in their genetic material. However, the evaluation of different environmental and genetic damage in such population is necessary to monitor possible damages.

Increase in DNA damage in lymphocytes and micronucleus frequency in buccal cells in silica-exposed workers

The alkaline single cell gel electrophoresis (comet assay) was applied to study the genotoxic properties of silica in human peripheral blood lymphocytes (PBL). The study was designed to evaluate the DNA damage of lymphocytes and the end points like micronuclei from buccal smears in a group of 45 workers, occupationally exposed to silica, from small mines and stone quarries. The results were compared to 20 sex and age matched normal individuals. There was a statistically significant difference in the damage levels between the exposed group and the control groups. The types of damages (type I –type 1V) were used to measure the DNA damage. The numbers of micronuclei were higher in the silica-exposed population. The present study suggests that the silica exposure can induce lymphocyte DNA damage and produces significant variation of micronuclei in buccal smear.

Chromosomal damage and apoptosis in exfoliated buccal cells from individuals with oral cancer

This study aimed to investigate cytological abnormalities indicative of chromosome damage (micronuclei) and apoptosis (karyorrhexis, pyknosis, and condensed chromatin) in exfoliated cells from the buccal mucosa of patients with oral cancer and control subjects. The sample included twenty individuals with oral cancer and forty individuals with normal buccal mucosa. Material was collected from the cheek epithelium in areas with lesions and areas without abnormalities. A minimum of one thousand cells was analyzed. Micronuclei were found significantly more frequently in cells collected from lesions than in cells from normal areas, independent of the presence/absence of cancer (P < 0.0001). They were also significantly more frequent in smokers and in mouthwash users (P < 0.0001). Apoptosis occurred significantly less frequently in individuals with oral cancer (P < 0.0001). These results show that oral cancer is associated with higher frequency of chromosomal damage and suggest that apoptosis is compromised in the buccal cells of individuals with this kind of neoplasia.

Effect of nickel and chromium exposure on buccal cells of electroplaters

The electroplating industry commonly involves the use of nickel and chromium. An assessment of the genotoxic effects of these metals can be carried out by micronucleus (MN) test in buccal cells. Other nuclear anomalies (NA) observed in buccal cells viz., karyorrhexis, pyknosis and karyolysis are also the indicators of genotoxicity. The current study aims at determining the extent of genotoxic damage in relation to the duration of exposure to nickel and hexavalent chromium via micronuclei induction and other nuclear anomalies. The present investigation included 150 subjects of which 50 individuals with no history of nickel/chromium exposure (Group I) were taken as control, 50 electroplaters exposed to nickel and hexavalent chromium for duration of less than 10 years (Group II) and 50 electroplaters exposed for ≥10 years (Group III) were included. Slides of buccal cells were prepared and the frequency of MN (‰) and NA (‰) were calculated. ANOVA was applied to test significance. Results were considered significant at p < 0.05 and p < 0.001. Group III showed the highest MN frequency (1.08 ± 0.54‰, p < 0.05), karyorrhexis (20.75 ± 6.29, p < 0.05), karyolysis (3.50 ± 1.91, p < 0.001), binucleate (4.75 ± 2.75, p < 0.05) and enucleated cells (5.75 ± 1.70, p < 0.05). Significant increase in frequencies between Group II and III was found as duration of exposure increased. Plasma nickel and chromium levels were also determined which showed a positive correlation with frequency MN and other nuclear abnormalities (p < 0.01).

Genotoxic damage in auto body shop workers

Some studies have shown increased DNA damage among car painters, but other professionals working in auto body and paint shops have not been extensively assessed. The aim of this study was to assess DNA damage in different types of auto body shop workers by measuring micronucleus (MN) levels in exfoliated buccal cells. The mean number of cells with MN per 2000 exfoliated buccal cells was analyzed in three groups of male workers: auto body repair technicians, painters, and office workers (control group). All participants answered a questionnaire inquiring about age, smoking habits, alcohol consumption, work practices, occupational exposure time, job activities, and use of protective equipment. The mean number of cells with MN was 3.50 ± 1.50 in auto body painters, 3.91 ± 2.10 in auto body repair technicians, and 0.80 ± 0.78 in office workers, with a significant difference between the control group and the two other groups (p = 0.0001). Age, occupational exposure time, use of protective masks, alcohol consumption, and smoking habit did not affect MN results. The findings indicate that technicians and painters working in auto body shops are at risk for genotoxic damage, while office workers seem to be protected.

Nuclear anomalies in the buccal cells of calcite factory workers

The micronucleus (MN) assay on exfoliated buccal cells is a useful and minimally invasive method for monitoring genetic damage in humans. To determine the genotoxic effects of calcite dust that forms during processing, MN assay was carried out in exfoliated buccal cells of 50 (25 smokers and 25 non-smokers) calcite factory workers and 50 (25 smokers and 25 non-smokers) age- and sex-matched control subjects. Frequencies of nuclear abnormalities (NA) other than micronuclei, such as binucleates, karyorrhexis, karyolysis and 'broken eggs', were also evaluated. Micronuclei and the other aforementioned anomalies were analysed by two way analysis of covariance. The linear correlations between the types of micronucleus and nuclear abnormalities were determined by Spearman's Rho. There was a positive correlation between micronuclei and other types of nuclear abnormalities in accordance with the Spearman's Rho test. Results showed statistically significant difference between calcite fabric workers and control groups. MN and NA frequencies in calcite fabric workers were significantly higher than those in control groups (p < 0.05). The results of this study indicate that calcite fabric workers are under risk of significant cytogenetic damage.

Genotoxic effects of X-rays on keratinized mucosa cells during panoramic dental radiography

OBJECTIVES

The aim of this study was to evaluate the genotoxic effects of X-rays on epithelial gingival cells during panoramic dental radiography using a differentiated protocol for the micronucleus test.

METHODS

40 healthy individuals who underwent this procedure for diagnostic purposes on request from their dentists agreed to participate in this study. All of them answered a questionnaire before the examination. Epithelial gingival cells were obtained from the keratinized mucosa of the upper dental arcade by gentle scraping with a cervical brush immediately before exposure and 10 days later. Cytological preparations were stained according to the Feulgen-Rossenbeck reaction, counterstained with fast green 1% for 1 min and analysed under a light microscope. Micronuclei, nuclear projections (broken eggs) and degenerative nuclear alterations (pyknosis, karyolysis, karyorrhexis and condensed chromatin) were scored.

RESULTS

The frequency of micronuclei was significantly higher after exposure (P < 0.05), as were the frequencies of nuclear alterations indicative of apoptosis (P < 0.001).

CONCLUSIONS

These results indicate that X-ray radiation emitted during panoramic dental radiography induces a genotoxic effect on epithelial gingival cells that increases the frequency of chromosomal damage and nuclear alterations indicative of apoptosis.

The effect of maras powder on DNA methylation and micronucleus formation in human buccal tissue

The plant powder "maras powder" (MP) has been used widely instead of cigarettes in the southeastern region of Turkey. The aim of this study was to assess the impacts of MP and cigarette smoking on the methylation and micronuclei (MN) formation in buccal cells of humans with a comparison to blood lymphocytes. DNA samples from 80 subjects (40 MP users, 20 tobacco smokers, 20 healthy volunteers) were analyzed for their genomic methylation status using Hpa II and Msp I digestions followed by a simple gel electrophoresis and ethidium bromide staining. A densitometric method was developed to measure the methylation in genomic DNA samples and the results were evaluated using a software program designed for this purpose. Buccal epithelial cells were collected from the same groups and examined for MN formation. The results indicated that a general genomic hypomethylation was present in almost all of the samples that were obtained from MP users and tobacco smokers. This hypomethylation was significant in MP users compared to smokers and healthy volunteers. The percentage of cells containing MN was 1.93 in MP users, 0.95 in healthy volunteers, and 1.82 in smokers. The MN frequency was significantly higher in MP users and smokers than in healthy volunteers. There was no statistical difference between smokers and MP users. Evidence indicates that MP usage induces DNA hypomethylation and increase frequency of MN formation.

Genotoxic biomonitoring study of population residing in pesticide contaminated regions in Göksu Delta: micronucleus, chromosomal aberrations and sister chromatid exchanges

Pesticides are widely used throughout the world in agriculture to protect crops and in public health to control diseases. Nevertheless, exposure to pesticides represents a potential risk to humans. This paper describes a study of possible genetic damage in the people living in regions contaminated with complex mixture of pesticides in Göksu Delta. In this study, used methods were chromosomal aberration (CA), sister chromatid exchange analysis (SCE) in the peripheral blood lymphocytes, and micronucleus (MN) assay in the buccal epithelial cells. In the present investigation, 32 affected subjects consist of 16 smoking and 16 non-smokings and an equal number of control subjects were assessed for genome damage. Micronucleus (MN), Broken egg (BE), Karyorrhexis (KR), Karyolysis (KL) and Binucleus (BN) frequencies were higher in affected subjects than in controls. Smoking had a statistically significant effect on the Micronucleus, Karyorrhexis and Binucleus frequencies for both the control and the exposed group. Also smoking and exposure affected the frequency of sister chromatid exchange and chromosomal aberrations compared with control groups.

Impact of air pollution and genotype variability on DNA damage in Prague policemen

DNA integrity was analyzed in the lymphocytes of 65 non-smoking city policemen during January and September 2004 using the comet assay combined with excision repair enzymes. Information about inhalation exposure was obtained by (1) stationary monitoring of PM2.5 and carcinogenic polycyclic aromatic hydrocarbons (cPAHs) during the sampling periods and (2) personal exposure monitoring of cPAHs 48h before blood sampling. The data were completed by a lifestyle questionnaire. Regardless of the season of the year, policemen working outdoors (exposed group) exhibited higher levels of DNA damage than those working indoors (controls). Within the exposed group, the levels of both unspecified and oxidative DNA damage detected in January significantly exceeded those found in September. The controls did not show analogous inter-seasonal variability. The winter levels of oxidative DNA damage positively correlated with exposure to cPAHs, probably reflecting increased oxidative stress as a result of high concentrations of PM2.5. In comparison with the wild type genotype, the carriers of at least one mutated allele, CYP1A1*2C (Ile/Val), MTHFR 2656 or MS 2656, and the EPHX1-medium phenotype appeared to be more susceptible specifically to the induction of oxidative DNA damage, while the p53 MspI mutation predisposed the carrier to a higher incidence of both breaks and oxidative lesions in DNA. In contrast, GSTM1-null and vitamin C tended rather to protect DNA integrity.

Effects of dietary boron on cervical cytopathology and on micronucleus frequency in exfoliated buccal cells

Recent evidence indicates that boron and borates may have anticarcinogenic properties. In this study, we have investigated the incidence of adverse cytological findings in cervical smears and the micronucleus (MN) frequency in women living in boron-rich and boron-poor regions. Cervical smears were prepared from 1059 women with low socioeconomic status; 472 of the women lived in relatively boron-rich rural areas, while 587 lived in relatively boron-poor regions. The average and standard deviation values for the age of the women screened with the cervical Pap smear test were 41.55 +/- 8.38. The mean dietary intake of boron was 8.41 mg/day for women from the boron-rich regions, and 1.26 mg/day for women living in the boron-poor regions (P < 0.0001). Women from the boron-rich regions had no cytopathological indications of cervical cancer, while there were cytopathological findings for 15 women from the boron-poor areas (chi(2) = 10.473, P < 0.05). Sixty women, 30 from each region, were chosen for evaluating MN frequencies in exfoliated buccal cells. MN frequencies for women from the boron-rich and boron-poor regions were not significantly different (t = -0.294, P > 0.05). Also, there were no significant correlations between age and MN frequency for women from both the boron-rich (r = 0.133, P = 0.48, P > 0.05) and boron-poor (r = -0.033, P = 0.861, P > 0.05) regions. The results suggest that ingestion of boron in the drinking water decreases the incidence of cervical cancer-related histopathological findings. There was no correlation between the pathological findings from the cervical smears and buccal cell MN frequency suggesting that the two study populations were exposed equally to gentotoxic agents. Nonetheless, cervical cancer-related histopathological findings should be validated by other researchers.

Evaluation of micronucleus frequencies and DNA damage in glass workers exposed to arsenic

Arsenic (As) is a known human carcinogen; however, very little is known about the health consequences of occupational exposure to As. In the present study, we assessed the genotoxic damage in the blood cells and in the buccal cells of south Indian glass factory workers who are occupationally exposed to As. The As content in the whole blood of 200 workers and 165 controls was evaluated with inductively coupled plasma mass spectrometry. Blood leukocytes from the subjects were monitored for the level of DNA damage using the Comet assay (mean comet tail length); buccal cells were used to determine the frequency of micronuclei (MN). The mean As concentration was significantly higher in the workers (56.76 microg/L) than in the controls (11.74 microg/L) (P < 0.001). The workers also had increased frequencies of MN in the buccal cells and increased levels of DNA damage in leukocytes compared to the controls (P < 0.001). There were significant correlations between the genotoxicity endpoints that were evaluated and blood As concentration, smoking, age, and the duration of working in the factory. Also, a significant correlation was observed between the frequency of MN and comet tail-length for the worker samples. Our findings indicate that chronic occupational exposure to As is genotoxic and that the Comet assay and micronucleus test are useful assays for evaluating genotoxicity in humans occupationally exposed to As.

Cytogenetic damage in buccal epithelia and peripheral lymphocytes of young healthy individuals exposed to ozone

Ozone (O(3)) is an important component of air pollution and a potent oxidant of biomolecules. To address the hypothesis that elevated ambient O(3) can induce cytogenetic damage in healthy people, we collected buccal cells from two groups of students (N = 126) from University of California, Berkeley, in the spring and again in the fall. One group spent their summer in the Los Angeles (LA) area where summer O(3) concentrations are significantly higher than in the San Francisco Bay (SF) area, and another remained in SF. During the school year, all students were exposed to low O(3) levels in SF. The micronucleus assay in a total of 611,000 buccal cells demonstrated that, in the fall, micronuclei (MN) in normal cells for the LA group had increased 39% relative to levels in the spring (1.52 and 0.87 MN/1,000 cells, respectively, P = 0.001). Students who spent the summer in SF had a 12.7% increase (P = 0.48). A similar effect of season was seen in degenerated buccal cells for the LA group (3.23 versus 1.88 MN/1,000 cells, P = 0.003). LA but not SF subjects also had more degenerated cells in the fall sample (P = 0.003). These findings were paralleled by an increase in MN and nucleoplasmic bridges in lymphocytes and MN in buccal cells in a sub-group of 15 students who underwent a 4-h controlled exposure to 200 p.p.b. O(3). This cytogenetic evidence, along with recent studies linking O(3) exposure to elevated lung cancer risk and mortality, suggest potential public health implications from exposures to high oxidant environments.

Viable human buccal mucosa cells do not yield typical nucleoids: impacts on the single-cell gel electrophoresis/Comet assay

Buccal mucosa (BM) cells have been used in human biomonitoring studies for detecting DNA adducts and chromosomal damage in an epithelial cell population. In the present study, we have investigated if human BM cells are suitable for use in the single-cell gel electrophoresis (SCGE)/Comet assay as an approach for estimating the exposure of epithelial cells to DNA-damaging agents. Our results indicate that only a few cells from BM cell samples yield comets that can be analyzed by current methods, and that the yield of cells with comets is independent of the percentage of viable BM cells in the sample. Data generated after enzymatic enrichment of viable cells and immunomagnetic separation of epithelial cells suggest that most of the BM cells that do form comets are probably leukocytes. Moreover, by reevaluating specific cells after running the Comet assay, we found that viable epithelial BM cells give rise to atypical comets that are not included in the analysis. Comparing DNA migration patterns between small groups of smokers and nonsmokers indicated that long-term smoking had no effect on the subpopulation of cells that yield typical comets. Our results indicate that the SCGE assay, as it is commonly performed, may not be useful for genotoxicity monitoring in human epithelial BM cells.

Cytogenetic biomonitoring in children with chronic tonsillitis: micronucleus frequency in exfoliated buccal epithelium cells

OBJECTIVE

To investigate the possible harmful cytogenetic effects associated with chronic tonsillitis by analyzing the micronucleus frequency and other nuclear abnormalities in exfoliated buccal epithelial cells.

MATERIALS AND METHODS

The study consisted of 20 children with chronic tonsillitis, and 20 control subjects with similar age and sex. The ages ranged between 5 and 12 years old (mean age: 7.5). The patients were diagnosed as having chronic tonsillitis on the basis of history, throat culture and clinical examinations. Buccal cell samples were collected with a wooden spatula. The samples were then applied to clean microscope slides. Smears were air dried and fixed in methanol:acetic acid. Then slides were stained by the Feulgen reaction technique. Three slides were prepared for each subject and 1000 cells were evaluated per slide to determine the frequencies of micronucleus and other nuclear abnormalities (binucleats, karyorrhexis and karyolysis). Statistically, Mann-Whitney U-test was used to analyze and compare the data.

RESULTS

The mean micronucleus frequencies in patient and control groups were 5.29+/-1.67 and 1.58+/-0.33, respectively. In the patient group, mean binucleus, karyorrhexis and karyolysis frequencies were 3.13+/-1.2, 2.04+/-0.64, and 1.74+/-0.47, respectively. However, in the control group, mean binucleus, karyorrhexis and karyolysis frequencies were 1.43+/-0.47, 1.26+/-0.45, and 0.88+/-0.27, respectively. The mean frequencies of all parameters in the patient group were higher than the control values, and the difference was found to be statistically significant (p<0.001).

CONCLUSION

Our results revealed that children with chronic tonsillitis could be under risk of significant cytogenetic damage.

Comparison of genetic damage in brazilian footwear-workers exposed to solvent-based or water-based adhesive

Research has shown that workers employed in footwear manufacture are at increased risk of some cancers, the strongest evidence being for nasal cancer and leukemia. Footwear-workers are routinely exposed to complex mixtures of solvents in degreasers, cleaners, primers, and adhesives used in the production process as toluene, n-hexane, acetone, and possibly dust particles, additives in shoe materials and degradation products of materials. The recognition of the potential health-hazards of solvent-based adhesives (SBAs) has lead to the development of adhesives with no organic solvents, the water-based adhesives (WBA). We investigated footwear-workers (all males) exposed to SBA (n=29) (for 3.98+/-4.13 years), and WBA (n=16), which had spent the six months previous to the study employed in an experimental section which used only water-based adhesives, although they had previously worked in sections which used solvent-based adhesives (for 5.80+/-4.03 years); 25 healthy subjects were used as controls. The Comet assay and the micronucleus test were used as endpoints, while the traditional parameters for assessing exposure to toluene in organic mixtures by measuring the concentration of urinary hippuric acid were also assessed. Our results showed a significantly lower mean concentration of hippuric acid in the control group than found in the SBA (P<0.001) and WBA (P<0.05) groups. The Comet assay results showed that there was a significant increase in the mean damage index for the SBA (P<0.001) group in comparison to the WBA group and control (P<0.05). For the micronucleus test in binucleated lymphocytes and exfoliated buccal cell, the three groups were not statistically different. Our study demonstrated that water-based adhesives are clearly a better option for safeguarding the health of footwear-workers, even with possibility of isocyanate presence, while the positive results observed in SBA group might be explained by chloroprene presence in the adhesive.

Micronuclei assessment in buccal cells of people environmentally exposed to arsenic in northern Chile

To determine the genotoxic risk associated to environmental arsenic exposure, the frequency of micronuclei in buccal cells (BCMN) of people drinking arsenic-contaminated water has been evaluated. A group of 105 individuals from the Antofagasta region (north Chile), and 102 individuals from the area of Concepcion, used as reference group, were included in the study. Arsenic concentration in drinking water was high (0.75 mg/L) in the Antofagasta area, 75-fold the maximum recommended level by WHO (0.01 mg/L), while the values obtained in Concepcion were significantly lower (0.002 mg/L). Individual measures of arsenic exposure were also determined in fingernails, which clearly confirm the existence of chronic exposure in the sampled populations from the Antofagasta region (10.15 microg/g versus 3.57 microg/g). The cytogenetic results indicate that, although the BCMN frequency is higher in exposed than in controls, this increase does not attain statistical significance. When the exposure biomarkers were related with the cytogenetic values, no correlations were observed between BCMN and arsenic content in water or in fingernails. In addition, the genotoxicity values do not seem to be related to the ethnic origin from people belonging to the exposed group. As a conclusion it appears that, in the studied population, the chronic ingestion of arsenic-contaminated water does not induce cytogenetic damage, measured as micronuclei, in the cells of the oral mucous in a significant extent.

Urban air pollution induces micronuclei in peripheral erythrocytes of mice in vivo

In this study, we explored the role of chronic exposure to urban air pollution in causing DNA damage (micronuclei frequency in peripheral erythrocytes) in rodents in vivo. Mice (n=20) were exposed to the urban atmosphere of São Paulo for 120 days (February to June 1999) and compared to animals (n=20) maintained in the countryside (Atibaia) for the same period. Daily levels of inhalable particles (PM10), CO, NO(2), and SO(2), were available for São Paulo. Occasional measurements of CO and O(3) were made in Atibaia, showing negligible levels of pollution in the area. The frequency of micronuclei (repeated-measures ANOVA) increased with aging, the highest values obtained for the 90th day of experiment (P<0.001). The exposure to urban air pollution elicited a significant (P=0.016) increase of micronuclei frequency, with no significant interaction with time of study. Associations (Spearman's correlation) between pollution levels of the week that precede blood sampling and micronuclei counts were observed in São Paulo. The associations between micronuclei counts and air pollution were particularly strong for pollutants associated with automotive emissions, such as CO (P=0.037), NO(2) (P<0.001), and PM10 (P<0.001). Our results support the concept that urban levels of air pollution may cause somatic mutations.

Biomonitoring of exposure to urban air pollutants: analysis of sister chromatid exchanges and DNA lesions in peripheral lymphocytes of traffic policemen

In order to elucidate the health effects of occupational exposure to traffic fumes, a few biomarkers of early genetic effect were investigated in Rome traffic policemen. One hundred and ninety healthy subjects engaged in traffic control (133 subjects) or in office work (57 subjects) participated the study. For all subjects, detailed information on smoking habits and other potential confounders were recorded by questionnaires. Average exposure of the study groups to benzene and other aromatic hydrocarbons was evaluated in a parallel exposure survey. All workers were genotyped for the following metabolic polymorphisms: CYP1A1 (m1, m2, and m4 variants), CYP2E1 (PstI and RsaI), NQO1 (Hinf1), GSTM1 and GSTT1 (null variants). In this paper, the results of the analysis of sister chromatid exchanges (SCE) in peripheral lymphocytes, and DNA damage by alkaline (pH 13) comet assay in mononuclear blood cells are reported. No statistically significant difference in the frequency of SCE or high frequency cells (HFC) was observed between traffic wardens and office workers (controls), despite the significantly higher exposure to benzene of the former (average group exposure 9.5 versus 3.8microg/m(3), 7h TWA). Conversely, both SCE per cell and HFC were highly significantly (P<0.001) increased in smokers compared to nonsmokers, showing a significant correlation (P<0.001) with the number of cigarettes per day. Multiple regression analyses of data, with metabolic polymorphisms, smoking habits, alcohol consumption, age, gender, and family history of cancer as independent variables, showed that smoking habits, and possibly the CYP2E1 variant genotypes, were the main factors explaining the variance of both SCE and HFC. Within smokers, an association of borderline significance between the CYP1A1 variant genotypes and increased SCE (P=0.050) and HFC (P=0.090) was found. This effect was mainly observed in light smokers (<15 cigarettes per day). The analysis of DNA damage by comet assay did not highlight any statistically significant difference between the exposed and control workers. Moreover, no significant model explaining tail moment variance was obtained by multiple regression analysis using the independent variables shown above. On the whole, these results indicate that exposure to moderate air pollution levels does not result in a detectable increase of genetic damage in blood cells. This evidence does not rule out any possibility of adverse effects, but strongly suggests that in urban residents life-style related factors, such as tobacco smoking, give the prevailing contribution to individual genotoxic burden.

Cytogenetic analysis of buccal cells from shoe-workers and pathology and anatomy laboratory workers exposed to n-hexane, toluene, methyl ethyl ketone and formaldehyde

People employed in the shoe manufacture and repair industry are at an increased risk for cancer, the strongest evidence being for nasal cancer and leukaemia. A possible causal role for formaldehyde is likely for cancer of the buccal cavity and nasopharynx. Exfoliated buccal cells are good source of tissue for monitoring human exposure to inhaled and ingested occupational and environmental genotoxicants. To assess the cytogenetic damage related to occupational exposure to airborne chemicals during shoe-making and the processes in pathology and anatomy laboratories, the micronuclei (MN) count per 3000 cells was measured in buccal smears from shoe-workers (group I, n = 22) exposed to mainly n-hexane, toluene and methyl ethyl ketone (MEK) and from anatomy and pathology staff (group II, n = 28) exposed to formaldehyde (FA). Eighteen male university staff were used as controls. The mean time-weighted average (TWA) concentrations of n-hexane, toluene and MEK in 10 small shoe workshops were 58.07 p.p.m., 26.62 p.p.m. and 11.39 p.p.m., respectively. The measured air concentrations of FA in the breathing zone of the anatomy and pathology laboratory workers were between 2 and 4 p.p.m. Levels of 2,5-hexadione (2,5-HD) and hippuric acid (HA), metabolic markers of n-hexane and toluene exposure, respectively, were significantly higher in the urine of workers in group I than in control subjects (p < 0.001 and p < 0.01, respectively). The mean (+/- SD) MN (0/00) [corrected] frequencies in buccal mucosa cells from workers in group I, group II and controls were 0.62 +/- 0.45%, 0.71 +/- 0.56% and 0.33 +/- 0.30%, respectively (p < 0.05 and p < 0.05 compared with controls for group I and group II, respectively). The effects of smoking, age and duration of exposure on the frequency of micronucleated buccal cells from workers in all three groups studied were also evaluated. Overall, the results suggest that occupational exposure to organic solvents, mainly n-hexane, toluene, MEK and FA, may cause cytogenetic damage in buccal cells and that use of exfoliated buccal cells seems to be appropriate to measure exposure to organic solvents.

Occupational exposure to pesticides and cytogenetic damage: results of a Hungarian population study using the micronucleus assay in lymphocytes and buccal cells

The frequency of micronuclei (MN) in peripheral blood lymphocytes and in buccal epithelial cells was used as a biomarker of genotoxic effects resulting from occupational exposure to pesticides. In addition, the cytokinesis-block proliferation index (CBPI) was calculated to detect possible variations in the proliferative kinetics of lymphocytes due to pesticide exposure. This study was performed on 84 pesticide-exposed workers and 65 unexposed controls from Hungary. The pesticide-exposed workers, classified as moderately and highly exposed, were also evaluated separately. Statistical evaluation of the cytogenetic biomarkers indicated that there were no significant differences between pesticide-exposed workers and controls, nor between moderately and highly exposed workers. Nevertheless, the statistical analysis revealed that additional factors such as age, sex, ingestion of raw vegetables, and working as a pesticide applicator affected lymphocyte MN frequency. In addition, age, sex, and smoking affected the frequency of MN in buccal cells. Results from the CBPI analysis showed that the proliferation index decreased with pesticide exposure and that this parameter was also affected by smoking and by the gender of individuals. The results of this study indicate no significant increase in MN in this group of Hungarian workers; however, the reduced CBPI in the highly exposed population suggests a possible genotoxic effect of pesticide exposure.

Micronuclei in peripheral blood lymphocytes and buccal epithelial cells of Polish farmers exposed to pesticides

In this biomonitoring study, we investigated whether an occupational exposure to a complex mixture of chemical pesticides produced a significant increase of micronuclei (MN) in both peripheral blood lymphocytes and buccal cells. Forty-nine male workers exposed to pesticides, from an agricultural area of Malopolska Region in Southern Poland, together with 50 men from the same area without indication of exposure to pesticides that served as controls, were used in this investigation. No statistically significant differences in the frequencies of cytogenetic damage were detected between exposed and control individuals, for either type of cells. The multiple linear regression analysis in the case of lymphocytes indicated that the studied cytogenetic endpoints were inversely influenced by alcohol; whilst a negative binomial regression, in the case of buccal cells, indicated that the MN values were directly influenced by the ingestion of red meat. An inverse negative relationship between the cytokinesis-block proliferation index and age, and a significant increase of miscarriages due to the exposure to pesticides were also observed.