Cytogenetic studies in coke oven workers

Environmental Monitoring of PAHs Exposure, Biomarkers and Vital Status in Coke Oven Workers

A follow-up study of a cohort of workers from a coke plant compared with a control group from the same industrial area was conducted in 2019. The recruitment and environmental and biomarker measurements were performed during 1993/1994. The environmental concentrations of polycyclic aromatic hydrocarbons (PAH), B(a)P, pyrene and nitro-PAH were measured. Personal data were collected via an individual semi-structured questionnaire by a trained physician. All biomarkers were measured after a specific blood drawing for every test. Significant risks (ORs) were observed for nitro-PAH (≥0.12 µg/m³) [OR = 7.96 (1.01–62.82)], urinary 1-hydroxypyrene (1-OHpy) (≥0.99 µmoles/moles of creatinine) [OR = 11.71 (1.47–92.90)], PAH DNA adducts (P³²) (≥2.69 adducts/10⁸ nucleotides) [OR = 5.46 (1.17–25.58)], total nitro-PAH hemoglobin adducts (≥161.68 fg/µg of Hb) [OR = 5.92 (1.26–27.86)], sister chromatid exchange (SCE) with TCR (≥377.84 SCE/cell chromosomes) [OR = 13.06 (3.95–93.10)], sister chromatid exchange with T (≥394.72 total SCE) [OR = 13.06 (3.95–93.10)], and sister chromatid exchange with X (≥8.19 mean SCE) [OR = 13.06 (3.95–93.10)]. Significant risk of death for all causes and chromosomal aberrations (48 h) (OR = 7.19 [1.19–43.44]) or micronuclei in culture at 48 h (OR = 3.86 [1.04–14.38]) were also found.

Genotoxic Effects of Benzo[a]pyrene and Dibenzo[a,l]pyrene in a Human Lung Cell Line

Several studies have shown that polycyclic aromatic hydrocarbons (PAHs) produce genotoxic effects in assays performed in vivo and in vitro. This study was undertaken to investigate the ability of benzo[ a]pyrene (BP) and dibenzo[ a,l]pyrene (DBP) to induce DNA damage in a human lung fibroblast cell line (MRC-5), using sister-chromatid exchanges test (SCEs), the comet assay, and evaluating point mutations in codon 12 of the K- ras protooncogene by polymerase chain reaction–single-strand conformation polymorphisms (PCR-SSCPs) and restriction fragment length polymorphisms (RFLP)-enriched PCR methods. Sister-chromatid exchanges frequencies were significantly increased in cells exposed to benzo[ a]pyrene and dibenzo[ a,l]pyrene in relation to controls ( p < .001). Using the standard alkaline comet assay, significant differences between groups were found for the variable comet moment (CM) when cells were exposed to BP ( p < .001) and DBP ( p < .001). Nevertheless, PCR-SSCP and RFLP-enriched PCR methods did not show any association between treatments with BP and DBP and K- ras point mutations. The data presented in this study indicated that BP and DBP induced both DNA strand breaks and sister-chromatid exchanges but not significant point mutations at codon 12 of K- ras gene in the MRC-5 cell line.

Systematic review of the use of the lymphocyte cytokinesis-block micronucleus assay to measure DNA damage induced by exposure to polycyclic aromatic hydrocarbons

The effect of exposure to polycyclic aromatic hydrocarbons (PAHs) to induce micronuclei (MN) measured using the lymphocytes cytokinesis-block micronucleus (CBMN) assay were evaluated in 34 studies according to the exposure: 20 studies in coke oven workers, 7 studies in different occupational exposures as alluminium industry workers, rubber factory workers, road construction workers, airport workers and diesel exposed workers, 6 studies on environmentaly exposed groups as police, volunteers and children. Reviewed papers indicate that the CBMN assay is a sensitive biomarker of PAHs exposure in polluted air. Reviewed studies confirmed previous conclusions, that the frequency of MN measured using the lymphocyte CBMN is not significantly affected by smoking, females are more sensitive to PAHs than males, the frequency of MN is increased with age.

Antaxia-telangiectasia mutated gene polymorphisms and susceptibility to chromosomal damage among polycyclic aromatic hydrocarbons exposed workers

The aim was to explore the relationship between the ataxia-telangiectasia mutated (ATM) gene polymorphisms and susceptibility to cytokinesis-block micronucleus among workers exposed to polycyclic aromatic hydrocarbons (PAH). Blood and urine samples of 140 PAH-exposed workers and 66 non-PAH-exposed workers were collected. Seven tagging single nucleotide polymorphisms in ATM gene were selected by pariwise r(2) method and minor allele frequency cutoff of 0.05 from Chinese genotype data in HapMap project. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used to analyze the polymorphisms of ATM rs600931, rs652311, rs227060, rs227292, rs624366, rs189037 and rs228589. The results showed that ATM rs600931 AG and AG+AA genotypes exhibited significantly higher cytokinesis-block micronucleus (CBMN) frequency (11.14+/-6.91 per thousand and 10.57+/-6.82 per thousand) than did the GG genotype (7.66+/-5.69 per thousand, P=0.015 and 0.038, respectively). The subjects with rs189037 GA and GA+AA genotypes exhibited significantly higher CBMN frequency (10.99+/-6.90 per thousand and 10.51+/-6.76 per thousand) than that of the GG genotype (7.72+/-5.82 per thousand, P=0.018 and 0.035, respectively). The PAH-exposed workers with rs624366 GC and GC+CC genotypes exhibited significantly higher CBMN frequency (11.34+/-6.74 per thousand and 10.73+/-6.62 per thousand) than did the GG genotype (7.61+/-6.07 per thousand, P=0.001 and 0.003, respectively). rs227092 GT genotype exhibited significantly higher CBMN frequency (10.78+/-6.60 per thousand) than did the GG genotype (7.91+/-6.30 per thousand, P=0.025) among the PAH-exposed workers. The haplotype pairs GGGGTGC/AAACATT exhibited significantly higher CBMN frequency (12.05+/-7.40 per thousand) than did the GGGGTGC/GGGGTGC (7.51+/-6.19 per thousand, P=0.007) among the PAH-exposed group. In conclusion, it is suggested that the polymorphisms of ATM were associated with the CBMN frequencies among PAH-exposed workers.

Effects of Genetic Polymorphisms of Metabolic Enzymes on Cytokinesis-Block Micronucleus in Peripheral Blood Lymphocyte among Coke-Oven Workers

Exploring the associations between genetic polymorphisms of metabolic enzymes and susceptibility to polycyclic aromatic hydrocarbon (PAH)–induced chromosomal damage is of great significance for understanding PAH carcinogenesis. Cytochrome P450, glutathione S-transferase, microsomal epoxide hydrolase, NAD(P)H:quinone oxidoreductase, and N-acetyltransferase are PAH-metabolizing enzymes. In this study, we genotyped for the polymorphisms of these genes and assessed their effects on cytokinesis-block micronucleus (CBMN) frequencies in peripheral blood lymphocytes among 141 coke-oven workers and 66 non–coke-oven worker controls. The geometric means of urinary 1-hydroxypyrene levels in coke-oven workers and the controls were 12.0 and 0.7 μmol/mol creatinine, respectively (P &lt; 0.01). The CBMN frequency (number of micronuclei per 1,000 binucleated lymphocytes) was significantly higher in coke-oven workers (9.5 ± 6.6‰) than in the controls (4.0 ± 3.6‰; P &lt; 0.01). Among the coke-oven workers, age was positively associated with CBMN frequency; the mEH His113 variant genotype exhibited significantly lower CBMN frequency (8.5 ± 6.5‰) than did the Tyr113/Tyr113 genotype (11.3 ± 6.4‰; P &lt; 0.01); the low mEH activity phenotype exhibited a lower CBMN frequency (8.6 ± 6.8‰) than did the high mEH activity phenotype (13.2 ± 6.7‰; P = 0.01); the GSTP1 Val105/Val105 genotype exhibited a higher CBMN frequency (15.0 ± 5.8‰) than did the GSTP1 Ile105/Ile105 or Ile105/Val105 genotypes (9.3 ± 6.5‰; P &lt; 0.01); the joint effect of high mEH activity phenotype and GSTM1 null genotype on CBMN frequencies was also found. Gene-environment interactions between occupational PAH exposure and polymorphisms of mEH and/or GSTM1 were also evident. These results indicate that the mEH, GSTP1, and GSTM1 polymorphisms may play a role in sensitivity or genetic susceptibility to the genotoxic effects of PAH exposure in the coke-oven workers.

Association between urinary 1-hydroxypyrene and genotoxic effects in coke oven workers

AIMS

To investigate whether current occupational exposure of coke oven workers to polycyclic aromatic hydrocarbons (PAHs) results in genotoxic effects measured in peripheral blood lymphocytes and whether these biomarkers are associated with the biomarkers of exposure.

METHODS

Blood and urine samples were collected immediately after a shift at the end of a working week from 50 coke oven workers and 50 control workers not exposed to PAHs. Methods included: (1) biomarkers of exposure: urinary 1-hydroxypyrene (HpU), urinary mutagenicity by the plate Salmonella test with strains TA98 and YG1024 after metabolic activation, expressed as mutagenic rate (MR98 and MR1024, respectively), urinary cotinine; and (2) biomarkers of biological effects in peripheral blood lymphocytes (PBL): sister chromatid exchanges (SCE/cell), cells of high frequency of SCE (% HFC), micronuclei (MN/1000 cells), chromosomal aberrations (CA/100 cells), and DNA damage by the Comet assay.

RESULTS

Occupational exposure to PAH resulted in significantly increased levels of HpU and mutagenic effect of urine. Median values of these biomarkers in coke oven workers were: 9.0 micromol/mol creatinine for HpU, 2.7 for MR98, and 8.2 for MR1024, compared to the controls: HpU = 0.6 micromol/mol creatinine, MR98 = 1.2, and MR1024 = 5.5. Occupational exposure caused significant induction of SCE, HFC, and MN in coke oven workers: median SCE = 5.9, HFC = 12.0%, MN = 6.0 compared to the controls: 3.9, 5.0%, and 3.0, respectively. No effect of occupational exposure was found in relation to CA and DNA damage measured with the Comet assay. HpU concentration was positively associated with SCE and HFC. The concentration of urinary 1-hydroxypyrene corresponding to a 5% probability of increased SCE was 1.0 micromol/mol creatinine.

CONCLUSIONS

The occupational exposure to PAHs resulted in measurable biological effects (SCE, HFC, MN). In coke oven workers an increased level of SCE was not observed below the level of 1.0 micromol HpU/mol creatinine.

The influence of occupational exposure to PAHs on the blood plasma levels of p53 and p21WAF1 proteins

Polycyclic aromatic hydrocarbons (PAHs) are the main source of carcinogenic risk among coke-oven workers. p53 is a tumor suppressor protein that is induced after DNA damage. It regulates the transcription of genes responsible for cell cycle arrest and apoptosis. p21(WAF1) protein is a downstream effector of p53; it induces cell cycle arrest either in the G(1), S, or G(2) phases. It has been shown that carcinogenic PAHs are able to induce the expression of both p53 and p21(WAF1) proteins in vitro. The purpose of the present study was to evaluate the effect of occupational exposure to carcinogenic PAHs on the level of p53 and p21(WAF1) proteins in blood plasma. The exposed group consisted of 66 coke-oven workers (males, average age 41 years, 42% smokers, 58% nonsmokers); the control group consisted of 49 machine workers (males, average age 49 years, 51% smokers, 49% nonsmokers). No difference in the plasma levels of either p53 (using anti-p53 antibody identifying both the mutated and the wild-type form of the protein) or p21(WAF1) protein was found between the exposed and control groups. Smoking had no effect on the levels of either protein in any of the analyzed groups. After stratification of all the subjects into groups according to their exposure to carcinogenic PAHs, a significantly higher level of p53 was found in the group exposed to carcinogenic PAHs <1 microg/m(3) as compared with the group exposed to carcinogenic PAHs >1 microg/m(3). A similar trend was observed for p21(WAF1) protein, even if no correlation between the levels of both proteins was detected. In the overall study a negative correlation between the levels of p53 protein and personal exposure to carcinogenic PAHs was found. These results did not support the expected response. The use of p53 as well as p21(WAF1) protein plasma levels as biomarkers of carcinogenic PAHs exposure requires further studies.

Mutagenic and cytotoxic effectiveness of zinc dimethyl and zinc diisononyldithiocarbamate in human lymphocyte cultures

The mutagenic and cytotoxic effectiveness of the vulcanisation accelerators zinc dimethyldithiocarbamate (ZDMC; ziram) and zinc diisononyldithiocarbamate (ZDINDC; arbestab Z) was tested in lymphocyte cultures of five healthy probands. ZDMC and ZDINDC (c=0.1, 1.0 and 10.0microg/ml) were studied in lymphocyte cultures without external metabolic activation. Additionally, incubation of the compounds (c=10.0microg/ml) was performed in the presence of liver microsomes from aroclor-induced rats (1 and 2h, 1 and 2mg microsomal protein). Genotoxicity testing was performed by analysis of chromosomal aberrations (CA), sister chromatid exchanges (SCEs) and micronuclei (MN). For evaluation of antiproliferative effects, mitotic index (MI) and cell cycle kinetics (CCK) were determined. In contrast to earlier investigations we found no significantly increased mutagenic or cytotoxic activity of ZDMC; ZDINDC also was inactive under these conditions.

Comparison of spontaneous and idoxuridine-induced micronuclei by chromosome painting

Fluorescence in situ hybridisation (FISH) technique with chromosome specific library (CSL) DNA probes for all human chromosomes were used to study about 9000 micronuclei (MN) in normal and idoxuridine (IUdR)-treated lymphocyte cultures of female and male donors. In addition, MN rates and structural chromosome aberrations were scored in Giemsa-stained chromosome spreads of these cultures. IUdR treatment (40 microg/ml) induced on the average a 12-fold increase of the MN rate. Metaphase analysis revealed no distinct increase of chromosome breaks but a preferential decondensation at chromosome 9q12 (28-79%) and to a lower extend at 1q12 (8-21%). Application of FISH technique with CSL probes to one male and one female untreated proband showed that all human chromosomes except chromosome 12 (and to a striking high frequency chromosomes 9, X and Y) occurred in spontaneous MN. In cultures containing IUdR, the chromosomal spectrum found in MN was reduced to 10 chromosomes in the male and 13 in the female proband. Eight chromosomes (2, 6, 12, 13, 14, 15, 17 and 18) did not occur in MN of both probands. On the contrary chromosomes 1 and especially 9 were found much more frequently in the MN of IUdR-treated cultures than in MN of control cultures. DAPI-staining revealed heterochromatin signals in most of the IUdR-induced MN. In an additional study, spontaneous and IUdR-induced MN were investigated in lymphocytes of another female donor using CSL probes only for chromosomes 1, 6, 9, 15, 16 and X. The results confirmed the previous finding that chromosomes 1 and 9 occur very often in MN after IUdR-treatment. The results indicate that decondensation of heterochromatic regions on chromosomes 1 and 9 caused by IUdR treatment strongly correlates with MN formation by these chromosomes.

Cytogenetic monitoring in coke oven workers

Cytogenetic markers (chromosomal aberrations, sister chromatid exchanges (SCE), cells with high frequency of SCE (HFC), the heterogeneity index SCE (SCE-H) and genetic polymorphism of genotypes GSTM1 and NAT2 were evaluated in the peripheral lymphocytes of 64 coke oven workers and 34 control subjects from the same plant. Personal monitors were used to evaluate exposure to eight carcinogenic (polycyclic aromatic hydrocarbons) PAHs, including B[a]P, during an 8-h working shift. Smoking habits were checked by urinary cotinine measurement. The exposure among coke oven workers ranged widely from 0.6 to 547 microgram/m3 and 2 to 50 137 ng/m3, for carcinogenic PAHs and B[a]P, respectively. The respective values in controls were 0.07 to 1.51 microgram/m3 and from 2 to 63 ng/m3. The results of biomonitoring in exposed vs. control subjects were as follows: frequency of chromosomal aberrations (% AB.C.), 2. 30% AB.C. vs. 1.09% AB.C. (P<0.05); sister chromatid exchanges, 7.47 SCE/cell vs. 5.49 SCE/cell (P<0.05); HFC, 5.94% vs. 2.06% (P<0.05) and SCE-H index, 1.49 vs. 1.01 (P<0.05). All the cytogenetic markers were significantly increased in the exposed vs. control groups. The effect of smoking was observed only in SCE when evaluated as HFC. Using individual exposure data for carcinogenic PAHs, a significant correlation between exposure and %AB.C. (r=0.372, P=0.0002), SCE/cell (r=0.331, P=0.001), HFC (r=0.467, P=0.007) and SCE/H (r=0. 286, P=0.004) was found. No effects of GSTM1 and NAT2 genotypes, individually or in combination, on the cytogenetic markers was observed. It is concluded that occupational exposure of coke oven workers involved in this study resulted in an increased level of chromosomal aberrations and SCE. The frequency of AB.C. and SCE/cell was found to be related to exposure to carcinogenic PAHs.

Coke oven workers study: the effect of exposure and GSTM1 and NAT2 genotypes on DNA adduct levels in white blood cells and lymphocytes as determined by 32P-postlabelling

The DNA adduct levels in total white blood cells (WBC) and lymphocytes (LYM) isolated from the blood of the same individuals were evaluated using the 32P-postlabelling assay for bulky aromatic adducts. In this study, 68 male coke oven workers and 56 machines workers as a matched control were enrolled. Personal monitors were used to evaluate exposure to eight carcinogenic PAHs, including B[alpha]P, during an 8-h working shift. The exposure among coke even workers ranged widely from 0.6 to 547 micrograms/m3 and from 2 to 62,107 ng/m3, for carcinogenic PAHs and B[alpha]P, respectively. The respective values in controls were from 0.07-1.64 microgram/m3 and from 1-63 ng/m3. A significant correlation between WBC- and LYM-DNA adduct levels was found (r = 0.591, P < 0.001). DNA adduct levels in both WBC and LYM were significantly elevated in coke oven workers as compared with controls, but adduct levels were generally low (WBC: medians 2.61 vs. 1.83 LYM: 2.47 vs. 1.65 adducts/10(8) nucleotides). LYM-DNA adduct levels were significantly higher for smokers as compared with nonsmokers in both the exposed and control groups. No such differences in WBC-DNA adduct levels were observed. Positive significant correlations were found at the individual level between DNA adducts in both cell types and carcinogenic PAHs and/or B[alpha]P in the inhaled air (r = 0.38-0.45, P < 0.001). A significant correlation at the individual level between LYM-DNA adducts and urinary cotinine was also observed (r = 0.37, P < 0.001). No differences in DNA adduct levels could be attributed to GSTM1 or NAT2 genotype in either group. Nor was there any clear association of DNA adduct levels with combined GSTM1/NAT2 genotypes. The effect of personal exposure to carcinogenic PAHs on DNA adduct levels in both cell types was also investigated using a logistic regression model with adjustment for possible modulating effect of confounders (smoking, GSTM1, NAT2, age, plasma levels of vitamins A and E, body mass index and diet). The results showed that coke oven workers had a significantly (P < 0.05) increased adjusted Odds Ratio (OR = 4.2 and 3.9 for WBC and LYM-DNA adducts) for occurrence of higher DNA adduct levels as compared to controls. The results also showed that the relative risk of an increased prevalence of 'abnormal' values of DNA adduct levels was exposure-dose related. The influence of confounding variables was found not to be significant in this study of relatively limited size. In spite of this, the results suggest that the DNA adduct levels in LYM seem to be affected by smoking (OR = 1.8 for smokers) and are modulated by the influence of NAT2 genotypes (OR = 1.6 for slow acetylators). Our findings indicate that both cell types are generally suitable to monitor occupational exposure to PAHs, and the results suggest that coke oven workers, smoking individuals and slow acetylators sustain more genetic damage in their LYM-DNA from exposure to carcinogenic PAHs than individuals without these actors.

Sister chromatid exchanges and high-frequency cells in men environmentally and occupationally exposed to ambient air pollutants: an intergroup comparison with respect to seasonal changes and smoking habit

Sister chromatid exchanges (SCE) and high-frequency cells (HFC) were measured in peripheral blood lymphocytes from men environmentally and occupationally exposed to a mixture of ambient air pollutants. The environmentally exposed individuals were inhabitants of the industrial region of Upper Silesia; those occupationally exposed were Silesian cokery or steel plant workers, while the control group consisted of rural region residents. A total of 147 males were enrolled in the study. Blood samples were collected in winter (February) and summer (September) seasons. Three major areas were investigated during the study: exposure-based dose dependency, seasonal changes, and influence of smoking habits on the SCE frequencies. The latter is frequently reported as a confounding factor in SCE analyses. In both winter and summer samples, statistically significant increases of SCE were observed in the environmentally and occupationally exposed groups compared to the controls (p < 0.001). The difference between both exposed groups was also significant (p < 0.001). An intergroup comparison was based on ANOVA after adjustment for smoking status. In all three groups of interest, a seasonal variation was found with higher levels in winter. However, in a part of the study in which each donor served as his own control, statistical differences were only found within the exposed groups. Control region inhabitants did not have significantly higher frequencies of SCE in winter, compared to summer samples. The impact of two major confounders, age of the donor and smoking habit, was investigated by multiple regression analysis. Smoking was a major factor influencing the level of SCE. Nevertheless, the effect was seen in winter samples only, which suggests an additive response and adds new information to this known effect.

Sister chromatid exchange induction in peripheral blood lymphocytes of traffic police workers

Traffic police workers, as a population exposed to urban atmosphere, were compared with a control population exposed to indoor air pollution levels. Sister chromatid exchanges (SCEs) as a biomarker of effect were measured in peripheral blood lymphocytes of 54 exposed subjects and 35 controls, and environmental concentration of polynuclear aromatic hydrocarbon (PAH) tracer compounds was detected by personal air samplers. The mean exposure level to benzo[a]pyrene in our group of traffic policemen (3.4 mg/m3) was in the range that has been estimated in urban areas in Europe during the last 10 years. No difference in SCE levels was found between exposed workers (7.36, SD 1.35) and controls (7.47, SD 1.28). No correlation was observed between SCE/cell and airborne PAH concentration in the traffic worker population. A positive regression of SCE on exposure estimate was found only in the non-smoking group of police workers. Our findings suggest that exposure to urban air pollution does not induce relevant cytogenetic effects.