Estimation of cytogenetic risk among coke oven workers exposed to polycyclic aromatic hydrocarbons.

Polycyclic aromatic hydrocarbons (PAHs) result from the incomplete combustion of natural or synthetic organic materials. The working environment at a coke plant can negatively affect the employed workers who were exposed to coke oven emissions containing PAHs, which formed and released into the environment by the process of pyrolysis of coke. This study aims to analyze the relationship between the exposure of PAHs and the risk of genetic damages such as chromosomal alteration (CA), micronucleus (MN), and DNA damage (PCR-RFLP) in peripheral blood lymphocytes of 27 coke oven workers and equal number of control subjects. The exposed subjects and controls were divided into two groups based on their age (group I<35 years and group II ≥35 years). The exposed subjects were further classified into two groups based on the exposure period (<12 years and ≥12 years). The frequencies of CA and MN in exposed subjects are relatively high with respect to controls. The XRCC1 399 Arg/gln polymorphism showed a substantial smaller difference in allele frequencies between exposed and control subjects. Based on present data, it was concluded that coke oven workers under risk should be monitored for adverse effects of the any long-term exposure.

Analysis of genetic damage and gene polymorphism in hepatocellular carcinoma (HCC) patients in a South Indian population.

BACKGROUND: Hepatocellular carcinoma (HCC) is the second leading cause of cancer death in many regions of Asia and the etiology of human HCC is clearly multi-factorial. The development of effective markers for the detection of HCC could have an impact on cancer mortality and significant health implications worldwide. The subjects presented here were recruited based on the serum alpha-fetoprotein level, which is an effective marker for HCC. Further, the chromosomal alterations were elucidated using trypsin G-banding. HCCs with p53 mutations have high malignant potential and are used as an indicator for the biological behavior of recurrent HCCs. The functional polymorphism in the XRCC1 gene, which participates in the base-excision repair of oxidative DNA damage, was associated with increased risk of early onset HCC. Thus, in this investigation, the p53 and XRCC1 gene polymorphisms using the standard protocols were also assessed to find out whether these genes may be associated with HCC susceptibility. METHODS: Blood samples from HCC patients (n = 93) were collected from oncology clinics in South India. Control subjects (n = 93) who had no history of tumors were selected and they were matched to cases on sex, age, and race. Peripheral blood was analyzed for chromosomal aberrations (CAs) and micronuclei (MN) formation. p53 and XRCC1 genotypes were detected using a PCR-RFLP technique. RESULTS: Specific biomarkers on cytogenetic endpoints might help in diagnosis and treatment measures. The frequencies of genotypes between groups were calculated by χ(2) test. A statistically significant (p < 0.05) increase in CA was observed in HCC patients compared to their controls as confirmed by ANOVA and MN shows insignificant results. The study on p53 Arg72Pro and XRCC1 Arg399Gln polymorphism in HCC patients demonstrated differences in allele frequencies compared to their controls. CONCLUSIONS: The present study indicates that chromosomal alterations and the genetic variations of p53 and XRCC1 may contribute to inter-individual susceptibility to HCC. A very limited role of genetic polymorphism was investigated in modulating the HCC risk, but the combined effect of these variants may interact to increase the risk of HCC in the South Indian population.

A comprehensive analysis of plausible genotoxic covariates among workers of a polyvinyl chloride plant exposed to vinyl chloride monomer.

The aim of this study was to assess the frequency of chromosomal aberrations-including chromatid type aberrations (CTAs), chromosomal type aberrations, micronucleus (MN) comet assay, and XRCC1 399 Arg/Gln polymorphism-in peripheral blood lymphocytes of workers occupationally exposed to vinyl chloride monomer (VCM). A total of 52 workers and an equal number of controls were recruited into the study to explore the potential cytogenetic risk of occupational exposure to VCM. Questionnaires were administered to obtain details of habitual cigarette-smoking, alcohol-consumption pattern, and occupation, etc. The exposed subjects and controls were classified into two groups based on age (group I <40 years; group II ≥40 years), and exposed subjects were further classified based on exposure duration (>8 and ≥8 years). CTA, MN, and comet assay frequency were significantly greater in polyvinyl chloride (PVC) factory workers (p < 0.05) with long-duration work. CTA, MN, and comet assay values were found to be increased with age in exposed subjects as well as in controls, with exposed subjects showing a statistically greater degree. An extensively greater MN frequency was observed in smokers exposed to VCM than in the control group (P < 0.05). The mean tail length of exposed subjects was greater compared with controls. The study on XRCC1 399 Arg/gln polymorphism in PVC factory workers showed less significant difference in allele frequency compared with controls. In conclusion, this results of work provides evidence for an apparent genotoxic effect associated with VCM exposure. Our results reinforce the greater sensitivity of cytogenetic assays for biomonitoring of occupationally exposed populations. Statistics indicate that workers exposed to VCM are at carcinogenic risk and should be monitored for long-term adverse effects from their exposure.

Evaluation of chromosomal alteration in electrical workers occupationally exposed to low frequency of electro magnetic field (EMFs) in Coimbatore population, India.

Extremely low frequency electro magnetic fields (EMFs) have been classified as possibly carcinogenic to humans by the International Agency for Research on Cancer. An increased number of chromosomal alterations in peripheral lymphocytes are correlated with elevated incidence of cancer. The aim of the present study was to assess occupationally induced chromosomal damage in EMF workers exposed to low levels of radiation. We used conventional metaphase chromosome aberration (CA) analysis and the micronucleus (MN) assay as biological indicators of non ionizing radiation exposure. In the present study totally 70 subjects were selected including 50 exposed and 20 controls. Informed written consent was obtained from all participants and the study was performed in accordance with the Declaration of Helsinki and the approval of the local ethical committee. A higher degree of CA and MN was observed in exposed subjects compared to controls, the frequency of CA being significantly enhanced with long years of exposure (P<0.05). Moreover increase in CA and MN with age was noted in both exposed subjects and controls, but was significantly greater in the former. The results of this study demonstrated that a significant induction of cytogenetic damage in peripheral lymphocytes of workers occupationally exposed to EMFs in electric transformer and distribution stations. In conclusion, our findings suggest that EMFs possess genotoxic capability, as measured by CA and MN assays; CA analysis appeared more sensitive than other cytogenetic end-points. It can be concluded that chronic occupational exposure to EMFs may lead to an increased risk of genetic damage among electrical workers.

Evaluation of genetic alterations in inhabitants of a naturally high level background radiation and Kudankulam nuclear power project site in India.

Evaluation of genetic alterations in inhabitants of an area of Tamil Nadu, India, chronically exposed to high background radiation (HBRA), was the major purpose of the present study. A total of 216 samples (exposed inhabitants, 108; control subjects, 108) were selected based on the confirmation of radiation dose level using thermoluminescence dosimetry (TLD). After signing a consent form, volunteers provided blood samples (5 ml each) to establish cell cultures at 52 h. One hundred complete metaphase cells from each subject were evaluated for karyotyping. The frequencies of chromosomal alterations (CA) were found to be higher in the exposed groups and the aberrations predominately observed were of chromatid-type. Smoking was found to have considerable effect on the frequency of CA in exposed subjects. With the comet assay for DNA damage, a significant increase in comet tail frequency was also observed in exposed subjects compared to controls. At present there are no radioepidemiological data regarding the cytogenetic studies in these areas. Furthermore, the Kudankulam nuclear power plant nuclear power plant is being constructed in the same area. The study gives potentially important information on the general health effects due to radiation exposure and increases people's understanding of the hazardous nature of chronic low level natural radiation exposure. However, we may conclude that the HBRA by itself does not pose any significant risk of genetic damage as measured by conventional cytogenetic analysis.

Evaluation of the genetic alterations in direct and indirect exposures of hexavalent chromium [Cr(VI)] in leather tanning industry workers North Arcot District, South India.

PURPOSE: The focal aim of the present study was to identify the genetic alterations occurring in the tannery workers and surrounding inhabitants chronically exposed to hexavalent chromium [Cr(VI)]. METHODS: A total of 108 samples which includes 72 exposed subjects [36 directly exposed (DE) subjects and 36 indirectly exposed (IE) subjects] and 36 controls were recruited for this study. The exposed subjects and controls were selected based on the Cr level present in air and their urine. Directly exposed subjects were categorized based on their work duration in the tannery industries, whereas the indirectly exposed subjects were categorized based on their year of residence in the place adjacent to tannery industries for more than 3 decades. Controls were normal and healthy. Age was matched for the exposed subjects and controls. The exposed subjects as well as the controls were categorized based on their age (group I, <40 years; group II, >41 years). Cell cultures were established from blood samples (5 ml from each subject) collected from the subjects (exposed subjects and controls) after obtaining informed consent. G-banding (Giemsa staining) of the cultures, micronucleus (MN) assay and comet assay were used to identify the genetic alterations of individuals exposed to Cr(VI) in comparison with the controls. RESULTS: A higher degree of total CA [12 ± 8.49 (21-25 years)] and MN [18.69 ± 7.39 (11-15 years)] was found in DE subjects compared to other groups. In IE subjects, elevated levels of CA [5.67 ± 1.15 (51-60 years)] and MN [25 ± 9.89 (71-80 years)] were observed. As expected, controls exhibited minimal number of alterations. The overall CA frequency due to Cr exposure was significantly different from that of the controls for both chromatid and chromosome type aberrations (P < 0.05 by ANOVA). The MN/1,000 binucleated cells were significantly increased (P < 0.05) in the peripheral lymphocytes of DE and IE subjects in comparison with controls. The mean tail length of comet assay for DE, IE and controls were analyzed. The mean tail length of DE subjects [4.21 (3.21-10.98)] was higher compared to that of IE subjects [3.98 (2.98-11.27)] and controls [3.01 (2.68-9.40)]. CONCLUSION: In conclusion, this work shows a clear genotoxic effect associated with chromium exposure, both directly and indirectly. Our result reinforces the higher sensitivity of cytogenetic assays for the biomonitoring of occupationally exposed populations. There is a strong need to educate those who work with potentially hazardous heavy about its adverse effects and highlight the importance of using protective measures.

Assessment of occupational cytogenetic risk, among petrol station workers.

The focal aim of this study was to assess the frequency of chromosomal aberrations (CA) including chromatid type aberrations (CTA) and chromosomal type aberrations (CSA), micronucleus (MN) and XRCC1 399 Arg/Gln polymorphism in the peripheral blood lymphocytes of 27 petrol pump workers and same number of controls to explore the possible cytogenetic risk on occupational exposure to petrol vapors. The exposed subjects and controls were classified into two groups based on their age (group I < 40 years; group II > 40 years) apart from the classification of the exposed subjects based on their exposure duration (> 8 and < 8 years). CTA and MN frequency were significantly higher in petrol pump workers (p < 0.05) with longer work duration. CTA was found to increase with age in the exposed subjects as well as controls, with exposed subjects showing a statistically higher degree. This effect was not observed in MN. A significantly higher frequency of MN was observed in the smoking petrol pump workers than in control smokers (p < 0.05). No association was found between smoking and CA in both subjects. The study on XRCC1 399 Arg/gln polymorphism in petrol pump workers demonstrated very less difference in allele frequency compared to controls. In conclusion, these datas indicate that petrol pump workers under risk group should be monitored for any long-term adverse effects of the exposure.

Cytogenetic methods for assessing human exposure to toluene in Coimbatore, South India.

The aim of the present study was to identify genetic alterations occurring in rotograving workers chronically exposed to toluene. A total of 60 samples from 30 exposed subjects and 30 age-matched controls, selected based on the toluene level present in their urine, were recruited. Exposed subjects were categorized based on their duration of exposure and smoking habitats. Controls were normal and healthy and categorized based on their smoking habits. Cell cultures were established from blood samples collected from the control and experimental subjects after obtaining informed consent. G-banding and comet assays were used to identify genetic alterations. A higher degree of total chromosome aberration was identified in exposed subjects compared to controls. As expected, controls exhibited minimal number of alterations. The overall CA frequency due to toluene exposure was significantly different from that of the controls for both chromatid and chromosome type aberrations (P\0.05 by ANOVA). . The habit of cigarette smoking among the workers had a synergistic effect on inducing DNA damage. In conclusion, this work shows a clear genotoxic effect associated with toluene exposure, our results also reinforcing the conclusion of higher sensitivity of cytogenetic assays for the biomonitoring of occupationally exposed populations. There is a strong need to educate those who work with potentially hazardous materials about adverse effects and highlight the importance of using protective measures.

Identification of Chromosomal Aberrations by Using Trypsin G-banding in Hepatocellular Carcinoma Patients (HCC) in Tamil Nadu, India.

Hepatocellular carcinoma (HCC) (or liver cancer) is one of the most common human malignancies worldwide. Aetiologically, HCC is closely associated with chronic hepatitis B and C virus infection, cirrhosis and alcohol intake. The objective of the present study was to elucidate the chromosomal abberations (CA) in HCC patients using the trypsin G-banding technique. This study may help in understanding the pattern of the disease and to assess whether these aberrations are associated with HCC susceptibility. The study examined 51 HCC cases and an equal number (n = 51) of age and gender matched cancer-free controls recruited from the hospitals in Tamil Nadu. The HCC cases were grouped depending upon their age into group I (≤ 45 years) and group II (≥ 46 years). The development of effective markers for the detection of HCC could have an impact on cancer mortality and may have significant public health implications worldwide. Subjects were recruited based on their alpha-fetoprotein (AFP) serum level, which is an effective marker for HCC. In the HCC cases, a higher number of chromatid aberrations [group I 13(25.5%) and group II 43(84.3%)] and CA [group I 10(19.6%) and group II 28(54.9%)] were observed. In contrast, controls showed a lower number of chromatid [group I 5(9.8%) and group II 12(23.5%)] and CA [group I 4(7.8%) and group II 9(17.6%)]. In conclusion, the results of this study contribute to the validation of CA as an intermediate end point in carcinogenesis. Because many people are unaware of this lethal disease, this study will raise awareness of this cancer.

DNA damage in viscose factory workers occupationally exposed to carbon di-sulfide using buccal cell comet assay

Aim: The most important industrial use of carbon disulfide (CS2) has been in the fabrication of regeneratedcellulose rayon by the viscose process and cellophane. CS2 leads to increased frequency of chromosomal aberrations in workers with occupational exposure to CS2. Methods: In the present study, the DNA damage was analyzed by using buccal cell comet assay for 30 viscose plant workers who are occupationally exposed to CS2 and 30 healthy individuals. Both groups were classified as smokers and non-smokers and only the experimental subjects were classified based on the exposure period. The data were analyzed statistically bythe Student’s t-test. Results: The results of this study showed increased levels of DNA damage among viscose plant workers. Conclusion: The habit of cigarette smoking among the viscose workers had a synergistic effect on inducing DNA damage.

Cytogenetic damage in khaini users of Tamilnadu, Southern India

Aim: The smokeless tobacco (ST) has a strong association with the risk of oral leukoplakia (OL), oral submucous fibrosis (OSF) and oral cancer (OC). ST components exhibit genotoxicity and may alter the structure of DNA, proteins and lipids, resulting in the production of antigenicity. In this study, an attempt was made to estimate the cytogenetic damage [chromosomal aberrations (CA) and micronucleus (MN)] in people habituated to consume khaini (ST), which is one of the major forms of tobacco consumption in Tamilnadu, India, and believed to be a major risk factor for OC. Methods: After signing a consent form, volunteers provided blood samples (108 samples from including experimental and control subjects) to establish cell cultures at 52 h. For CA analysis, 100 complete metaphase cells per subject were evaluated. Chromatid- and chromosomal- type aberrations were identified in experimental and control subjects, where the latter showed a very minimal number of CA in age wise manner. Results: Statistically significant results were obtained in experimental subjects when compared to controls as confirmed by chi-square test. Exfoliated cells from the buccal mucosaof Khaini users were examined by using the micronucleus assay. The difference in mean micronucleated cell count for buccal mucosa between cases and controls were significant (p<0.01). Hence, specific biomarkers on cytogenetic endpoints might help in establishing preventive measures to reduce cancer risks. Conclusion: the genotoxic effect of smokeless tobacco should be considered in addition to other known hazards for assessing health risks.