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

The Comet Assay as a Tool in Human Biomonitoring Studies of Environmental and Occupational Exposure to Chemicals-A Systematic Scoping Review

Biomonitoring of human populations exposed to chemical substances that can act as potential mutagens or carcinogens, may enable the detection of damage and early disease prevention. In recent years, the comet assay has become an important tool for assessing DNA damage, both in environmental and occupational exposure contexts. To evidence the role of the comet assay in human biomonitoring, we have analysed original research studies of environmental or occupational exposure that used the comet assay in their assessments, following the PRISMA-ScR method (preferred reporting items for systematic reviews and meta-analyses extension for scoping reviews). Groups of chemicals were designated according to a broad classification, and the results obtained from over 300 original studies (n = 123 on air pollutants, n = 14 on anaesthetics, n = 18 on antineoplastic drugs, n = 57 on heavy metals, n = 59 on pesticides, and n = 49 on solvents) showed overall higher values of DNA strand breaks in the exposed subjects in comparison with the unexposed. In summary, our systematic scoping review strengthens the relevance of the use of the comet assay in assessing DNA damage in human biomonitoring studies.

Cytogenetic analysis of coke oven workers in Eastern Slovakia

OBJECTIVE

Our study aimed to evaluate the extent of polycyclic aromatic hydrocarbon (PAH) exposure in coke oven workers from Eastern Slovakia by cytogenetic analysis of human peripheral lymphocytes.

METHODS

A total of 81 peripheral blood samples were collected from PAH-exposed workers (mean age 45.84 ± 9.73 years) and 30 samples constituted the control group (41.93 ± 15.39 years). The samples were processed using routine cytological analysis. Conventional cytogenetic analysis of human peripheral lymphocytes has been used to evaluate the effects of PAHs.

RESULTS

Comparison of the aberrant cells in the total exposed with the controls showed a significant difference (p < 0.05). A high level of significance (p < 0.001) was observed when comparing the gaps between the exposed group and the control group. There was a significant difference (p < 0.01) in aberrant cells and chromatid breaks (p < 0.05) in the GR1 working subgroup compared with the control group. The results of the correlation analysis did not show a significant relationship between the length of occupational exposure and the frequency of aberrant cells (r = 0.071, p = 0.529). Similarly, no association was observed between smoking among coke plant workers and the frequency of aberrant cells (r = 0.117, p = 0.538).

CONCLUSION

Cytogenetic analysis showed an increased frequency of chromosomal aberrations in coke oven workers in Eastern Slovakia.

Unveiling Urinary Mutagenicity by the Ames Test for Occupational Risk Assessment: A Systematic Review

Occupational exposure may involve a variety of toxic compounds. A mutagenicity analysis using the Ames test can provide valuable information regarding the toxicity of absorbed xenobiotics. Through a search of relevant databases, this systematic review gathers and critically discusses the published papers (excluding other types of publications) from 2001-2021 that have assessed urinary mutagenicity (Ames test with Salmonella typhimurium) in an occupational exposure context. Due to the heterogeneity of the study methods, a meta-analysis could not be conducted. The characterized occupations were firefighters, traffic policemen, bus drivers, mail carriers, coke oven and charcoal workers, chemical laboratory staff, farmers, pharmacy workers, and professionals from several other industrial sectors. The genetically modified bacterial strains (histidine dependent) TA98, TA100, YG1041, YG1021, YG1024 and YG1042 have been used for the health risk assessment of individual (e.g., polycyclic aromatic hydrocarbons) and mixtures of compounds (e.g., diesel engine exhaust, fire smoke, industrial fumes/dyes) in different contexts. Although comparison of the data between studies is challenging, urinary mutagenicity can be very informative of possible associations between work-related exposure and the respective mutagenic potential. Careful interpretation of results and their direct use for occupational health risk assessment are crucial and yet complex; the use of several strains is highly recommended since individual and/or synergistic effects of complex exposure to xenobiotics can be overlooked. Future studies should improve the methods used to reach a standardized protocol for specific occupational environments to strengthen the applicability of the urinary mutagenicity assay and reduce inter- and intra-individual variability and exposure source confounders.

Elevated urinary mutagenicity among those exposed to bituminous coal combustion emissions or diesel engine exhaust

Urinary mutagenicity reflects systemic exposure to complex mixtures of genotoxic/carcinogenic agents and is linked to tumor development. Coal combustion emissions (CCE) and diesel engine exhaust (DEE) are associated with cancers of the lung and other sites, but their influence on urinary mutagenicity is unclear. We investigated associations between exposure to CCE or DEE and urinary mutagenicity. In two separate cross-sectional studies of nonsmokers, organic extracts of urine were evaluated for mutagenicity levels using strain YG1041 in the Salmonella (Ames) mutagenicity assay. First, we compared levels among 10 female bituminous (smoky) coal users from Laibin, Xuanwei, China, and 10 female anthracite (smokeless) coal users. We estimated exposure-response relationships using indoor air concentrations of two carcinogens in CCE relevant to lung cancer, 5-methylchrysene (5MC), and benzo[a]pyrene (B[a]P). Second, we compared levels among 20 highly exposed male diesel factory workers and 15 unexposed male controls; we evaluated exposure-response relationships using elemental carbon (EC) as a DEE-surrogate. Age-adjusted linear regression was used to estimate associations. Laibin smoky coal users had significantly higher average urinary mutagenicity levels compared to smokeless coal users (28.4 ± 14.0 SD vs. 0.9 ± 2.8 SD rev/ml-eq, p = 2 × 10-5 ) and a significant exposure-response relationship with 5MC (p = 7 × 10-4 ). DEE-exposed workers had significantly higher urinary mutagenicity levels compared to unexposed controls (13.0 ± 10.1 SD vs. 5.6 ± 4.4 SD rev/ml-eq, p = .02) and a significant exposure-response relationship with EC (p-trend = 2 × 10-3 ). Exposure to CCE and DEE is associated with urinary mutagenicity, suggesting systemic exposure to mutagens, potentially contributing to cancer risk and development at various sites.

The influence of demographic and lifestyle factors on urinary levels of PAH metabolites-empirical analyses of Cycle 2 (2009-2011) CHMS data

Polycyclic aromatic hydrocarbons (PAHs) are a group of compounds formed during the incomplete combustion of organic matter. Several are mutagenic carcinogens; the magnitude of exposure can be assessed by examining urinary levels of PAH metabolites. Data from biomonitoring studies that record urinary PAH metabolite levels, as well as demographic and lifestyle information, can be used to investigate relationships between PAH exposure and variables, such as smoking status, workplace smoking restrictions, age, sex, household income, home age, and occupation. This study analysed creatinine-adjusted urinary PAH metabolite concentrations and questionnaire data from ~1200 individuals aged 16 years and older surveyed in Cycle 2 of the Canadian Health Measures Survey (CHMS). Statistical analyses revealed that smoking status, age, and sex are associated with urinary concentrations of a pyrene metabolite (1-OHP), phenanthrene metabolites (ΣOH-Phen), fluorene metabolites (ΣOH-Flu) and naphthalene metabolites (ΣOH-Nap). More specifically, smoking status, age and sex can collectively account for 30, 24, 52, and 34% of the observed variations in 1-OHP, ΣOH-Phen, ΣOH-Flu and ΣOH-Nap metabolites, respectively (p < 0.001). Analyses of non-smokers revealed weak but significant effects of age, sex, home age, and occupation on urinary levels of selected PAH metabolites (i.e., <7% of observed variation, p < 0.05). The unexplained variation in PAH metabolite levels is most likely related to diet, which was not examined. Although the results revealed significant relationships between urinary PAH metabolite levels and several lifestyle and/or demographic variables, robust examinations of selected effects (e.g., sex, home age, occupation) will require datasets that are balanced with respect to the other highlighted variables. The results can be used to identify remedial measures to reduce exposure and concomitant risk, and/or design follow-up studies to test hypotheses regarding the causes of exposure differences empirically related to sex, age, home age, and occupation.

Urinary mutagenicity and oxidative status of wildland firefighters working at prescribed burns in a Midwestern US forest

OBJECTIVE

Wildland firefighters (WLFFs) experience repeated exposures to wildland fire smoke (WFS). However, studies about WLFFs remain regionally limited. The objective of this study was to assess the effect of WFS exposure on urinary mutagenicity and cell oxidation among WLFFs who work at prescribed burns in the Midwestern USA.

METHODS

A total of 120 spot urine samples was collected from 19 firefighters right before (pre-shift), immediately after (post-shift), and the morning (next-morning) following work shifts on prescribed burn days (burn days) and regular workdays (non-burn days). The levels of urinary mutagenicity, 8-isoprostane, malondialdehyde and oxidised guanine species (Ox-GS) were measured. Linear mixed-effect models were used to determine the difference of cross-shift changes in the concentrations of urinary biomarkers.

RESULTS

Post-shift levels of creatinine-corrected urinary mutagenicity and 8-isoprostane were non-significantly higher than pre-shift levels (1.16× and 1.64×; p=0.09 and 0.07) on burn days. Creatinine-corrected Ox-GS levels increased significantly in next-morning samples following WFS exposure (1.62×, p=0.03). A significant difference in cross-shift changes between burn and non-burn days was observed in 8-isoprostane (2.64×, p=0.03) and Ox-GS (3.00×, p=0.02). WLFFs who contained the fire (performed holding tasks) had a higher pre-morning to next-morning change in urinary mutagenicity compared with those who were lighting fires during the prescribed burns (1.56×, p=0.03).

CONCLUSIONS

Compared with the other regions, WLFFs who worked in Midwestern forests had an elevated urinary mutagenicity and systemic oxidative changes associated with WFS exposure at prescribed burns.

Dose-related telomere damage associated with the genetic polymorphisms of cGAS/STING signaling pathway in the workers exposed by PAHs

Telomeres are located at the end of eukaryotic chromosomes and vulnerable to exogenous chemical compounds. Exposure to coke oven emissions (COEs) leads to a dose-related telomere damage, and such chromosomal damage might trigger the cGAS/STING signaling pathway which plays an important role in immune surveillance. However, the relationship between the genetic variations in the cGAS/STING signaling pathway and telomere damage in the COEs-exposure workers has not been investigated. Therefore, we recruited 544 coke oven workers and 238 healthy control participants, and determined the level of COEs exposure, concentration of urinary 1-hydroxypyrene (1-OHPYR), genetic polymorphisms and telomere length. The results showed that the telomere length significantly decreased from the control-to high-exposure groups as defined by the external exposure level (P < 0.05). The results also indicated that STING rs7447927 CC, cGAS rs34413328 AA, and cGAS rs610913 AA could inhibit telomere shortening in the exposure group (P < 0.05), and cGAS rs34413328, urine 1-OHPYR and cumulative exposure dose (CED) had a significant association with telomere length by generalized linear model. In conclusion, telomere shortening was a combined consequence of short-term exposure, long-term exposure, and genetic variations among the COEs-exposure workers.

Effects of polycyclic aromatic hydrocarbon exposure and miRNA variations on peripheral blood leukocyte DNA telomere length: A cross-sectional study in Henan Province, China

Telomeres play a major role in human aging and disease, especially in most cancers. Telomere length was shortened in workers exposed to polycyclic aromatic hydrocarbons (PAHs) and influenced by individual genetic variations in telomere-binding proteins. MicroRNAs (miRNAs) can affect the progress of messenger RNA (mRNA) transcription; however, whether polymorphisms in miRNA can act on the telomere length is still unknown. Therefore, we aimed to explore the relationships between telomere damage and genetic polymorphisms in miRNA or environmental exposure. A total of 544 coke oven workers and 238 healthy controls were recruited. After collecting peripheral blood and extracting the genomic DNA of the study subjects, the telomere length (TL) in their leucocytes was detected by a real-time quantitative polymerase chain reaction (PCR), and polymorphisms in miRNAs were genotyped using the flight mass spectrometry technique. The concentrations of the four urine OH-PAHs were determined by high performance liquid chromatography (HPLC), and the Soxhlet extraction method was used to detect the concentration of coke oven emissions (COEs) in the air. We found that the peripheral blood leucocyte DNA TL was significantly shorter in the exposure group (0.75; 0.51, 1.08) than that in the control group (1.05; 0.76, 1.44) (Z = 7.692, P < 0.001). The total cumulative exposure dose (CED), 1-hydroxypyrene, 2-hydroxynaphthalene, and 3-hydroxyphenanthrene were significantly negatively correlated with TL (r = -0.307, P < 0.001; r = -0.212, P < 0.001; r = -0.110, P = 0.025; r = -0.251, P < 0.001, respectively). MiR-145 rs353291 GG, miR-30a rs2222722 CT/CC, and miR-197 rs1889470 AA could protect the telomere end in the exposed workers (P < 0.05). The interaction between miR-197 rs1889470 and the CED had an effect on TL (β = 0.066, P = 0.034). This is the first study to evaluate gene-environmental interactions for miRNA polymorphisms and PAH exposure in coke oven workers.

Firefighters exposure to fire emissions: Impact on levels of biomarkers of exposure to polycyclic aromatic hydrocarbons and genotoxic/oxidative-effects

Firefighters represent one of the riskiest occupations, yet due to the logistic reasons, the respective exposure assessment is one of the most challenging. Thus, this work assessed the impact of firefighting activities on levels of urinary monohydroxyl-polycyclic aromatic hydrocarbons (OHPAHs; 1-hydroxynaphthalene, 1-hydroxyacenaphthene, 2-hydroxyfluorene, 1-hydroxyphenanthrene, 1-hydroxypyrene, 3-hydroxybenzo(a)pyrene) and genotoxic/oxidative-effect biomarkers (basal DNA and oxidative DNA damage) of firefighters from eight firehouses. Cardiac frequency, blood pressure and arterial oxygen saturation were also monitored. OHPAHs were determined by liquid-chromatography with fluorescence detection, while genotoxic/oxidative-effect biomarkers were assessed by the comet assay. Concentrations of total OHPAHs were up to 340% higher (p ≤ 0.05) in (non-smoking and smoking) exposed workers than in control subjects (non-smoking and non-exposed to combat activities); the highest increments were observed for 1-hydroxynaphthalene and 1-hydroxyacenaphthene (82-88% of ∑OHPAHs), and for 2-hydroxyfluorene (5-15%). Levels of biomarker for oxidative stress were increased in non-smoking exposed workers than in control group (316%; p ≤ 0.001); inconclusive results were found for DNA damage. Positive correlations were found between the cardiac frequency, ∑OHPAHs and the oxidative DNA damage of non-smoking (non-exposed and exposed) firefighters. Evidences were raised regarding the simultaneous use of these biomarkers for the surveillance of firefighters' health and to better estimate the potential short-term health risks.

Filaggrin variations are associated with PAH metabolites in urine and DNA alterations in blood

Dermal chemical exposure is common in many professions. The filaggrin protein is important for the skin barrier and variations in the filaggrin gene (FLG) may influence the uptake of chemicals via the skin, and consequently, the degree of systemic effects. The aim of this study was to investigate, in chimney sweeps with occupational exposure to polycyclic aromatic hydrocarbons (PAH) from soot, the influence of variation in FLG on internal PAH dose and DNA alterations, including epigenetic, previously linked to cancer and cardiovascular disease. We used TaqMan PCR to genotype 151 chimney sweeps and 152 controls for four FLG null variants (R501X, R2447X, S3247X and 2282del4) which cause impaired skin barrier, and FLG copy number variation (12th repeat, CNV12) which potentially is beneficial for the skin barrier. The internal dose of PAH was represented by urinary PAH metabolites (e.g. 1-hydroxypyrene and 3-hydroxybenzo[a]pyrene) that we measured by LC-MS/MS. We measured epigenetic alterations (methylation of AHRR and F2RL3) in blood by pyrosequencing; and DNA alterations (telomere length and mitochondrial DNA copy number) by real-time PCR. Hypomethylation of AHRR or F2RL3 is a risk factor for lung cancer and shorter telomere length a risk factor for cardiovascular disease. The frequencies of FLG null were 8.6 and 11.8% (p = 0.35), and CNV12 27.8 and 19.7% (p = 0.09) in chimney sweeps and controls, respectively. We found that among chimney sweeps working predominately with soot sweeping (high PAH exposure), CNV12 carriers had lower concentrations of PAH metabolites in urine compared with non-carriers (median 1-hydroxypyrene = 0.37 vs 0.86 μg/g creatinine respectively; p = 0.025 by linear regression models adjusted for age, BMI and smoking) compared to sweeps not carrying CNV12. Further, FLG null was associated with approximately 2.5% higher methylation of F2RL3 (cg03636183, p = 0.019 after adjustment for exposure group, age, BMI and smoking). FLG null was associated with approximately 7% shorter telomere length (p = 0.015, adjusted model). Our results suggest that FLG variations may influence the dose of PAH in highly exposed workers, possibly via dermal uptake. It also suggests that FLG variation may influence the degree of (epi)genotoxicity in the body. FLG variation is common in the working population and should be considered in risk assessment.

Elevated Exposures to Polycyclic Aromatic Hydrocarbons and Other Organic Mutagens in Ottawa Firefighters Participating in Emergency, On-Shift Fire Suppression

Occupational exposures to combustion emissions were examined in Ottawa Fire Service (OFS) firefighters. Paired urine and dermal wipe samples (i.e., pre- and post-event) as well as personal air samples and fire event questionnaires were collected from 27 male OFS firefighters. A total of 18 OFS office workers were used as additional controls. Exposures to polycyclic aromatic hydrocarbons (PAHs) and other organic mutagens were assessed by quantification of urinary PAH metabolite levels, levels of PAHs in dermal wipes and personal air samples, and urinary mutagenicity using the Salmonella mutagenicity assay (Ames test). Urinary Clara Cell 16 (CC16) and 15-isoprostane F_2t (8-iso-PGF_2α) levels were used to assess lung injury and overall oxidative stress, respectively. The results showed significant 2.9- to 5.3-fold increases in average post-event levels of urinary PAH metabolites, depending on the PAH metabolite (p < 0.0001). Average post-event levels of urinary mutagenicity showed a significant, event-related 4.3-fold increase (p < 0.0001). Urinary CC16 and 8-iso-PGF_2α did not increase. PAH concentrations in personal air and on skin accounted for 54% of the variation in fold changes of urinary PAH metabolites (p < 0.002). The results indicate that emergency, on-shift fire suppression is associated with significantly elevated exposures to combustion emissions.

S phase arrest in lymphocytes induced by urinary 1-hydroxypyrene and alcohol drinking in coke oven workers

Arrest of the cell cycle after DNA damage is believed to promote DNA repair. We aim to investigate the main factors affecting cell cycle arrest of lymphocytes in coke oven workers. A total of 600 workers were included in this study, and their urinary levels of four polycyclic aromatic hydrocarbons (PAH) metabolites, 8-hydroxydeoxyguanosine (8-OHdG), and cell cycle distribution were determined. Urinary PAH metabolites were significantly increased in coke oven workers ( p < 0.01). It was found that only urinary 2-hydroxynaphthalene and 1-hydroxypyrene showed significant positive linear dose–response effects on 8-OHdG in this study population ( ptrend = 0.025 and 0.017, respectively). The dose–response effect was also observed for smoking and drinking on 8-OHdG ( ptrend < 0.001 and 0.034, respectively). Multivariate logistic regression analysis revealed that high levels of urinary 1-hydroxypyrene were associated with a significantly increased risk of S phase arrest (odds ratio (OR) = 1.32, p = 0.03), so as heavy alcohol drinking (OR = 1.31, p = 0.02). Drinking can significantly modify the effects of urinary 1-hydroxypyrene on S phase arrest, during co-exposure to both heavy drinking and median or high 1-hydroxypyrene levels (OR = 3.31, 95% confidence interval (CI) = 1.21–7.63 and OR = 2.56, 95% CI = 1.08–6.06, respectively). Our findings demonstrate that coke oven workers with heavy drinking will cause S phase arrest so as to repair more serious DNA damage.

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.

Urinary elimination kinetics of 3-hydroxybenzo(a)pyrene and 1-hydroxypyrene of workers in a prebake aluminum electrode production plant: Evaluation of diuresis correction methods for routine biological monitoring

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous carcinogenic pollutants emitted in complex mixtures in the ambient air and contribute to the incidence of human cancers. Taking into account all absorption routes, biomonitoring is more relevant than atmospheric measurements to health risk assessment, but knowledge about how to use biomarkers is essential. In this work, urinary elimination kinetic of 1-hydroxypyrene (1-OHP) and 3-hydroxybenzo(a)pyrene (3-OHBaP) were studied in six electrometallurgy workers after PAHs exposure. Spot samples were collected on pre- and post-shift of the last workday then the whole urinations were separately sampled during the weekend. Non-linear mixed effects models were built to study inter- and intra-individual variability of both urinary metabolites toxicokinetic and investigate diuresis correction ways. Comparison of models confirmed the diuresis correction requirement to perform urinary biomonitoring of pyrene and BaP exposure. Urinary creatinine was found as a better way than specific gravity to normalize urinary concentrations of 1-OHP and as a good compromise for 3-OHBaP. Maximum observed levels were 1.0 µmol/mol creatinine and 0.8nmol/mol creatinine for 1-OHP and 3-OHBaP, respectively. Urinary 1-OHP concentrations on post-shift were higher than pre-shift for each subject, while 3-OHBaP levels were steady or decreased, and maximum urinary excretion rates of 3-OHBaP was delayed compared to 1-OHP. These results were consistent with the sampling time previously proposed for 3-OHBaP analysis, the next morning after exposure. Apparent urinary half-life of 1-OHP and 3-OHBaP ranged from 12.0h to 18.2h and from 4.8h to 49.5h, respectively. Finally, inter-individual variability of 1-OHP half-life seemed linked with the cutaneous absorption extent during exposure, while calculation of 3-OHBaP half-life required the awareness of individual urinary background level. The toxicokinetic modeling described here is an efficient tool which could be used to describe elimination kinetic and determine diuresis correction way for any other urinary biomarkers of chemicals or metals exposure.

Synergistic increase of oxidative stress and tumor markers in PAH-exposed workers

In this study, we investigated oxidative stress and tumor marker levels of polycyclic aromatic hydrocarbons (PAHs) in 136 coke oven workers and in 60 control subjects, and evaluated the correlation between oxidative stress and tumor marker levels. Questionnaires on basic demographic information were also administered. Significant differences in employment time and percentages of alcohol drinkers were observed between the control and exposed groups. PAH exposure was assessed using urinary 1-hydroxy-pyrene (1-OHP) levels and was found to be significantly higher in workers than in the controls. Significant differences (P<0.001) of MDA, GST, LDH, NSE, Cyfra21-1, and of SCC and TNF-a (P<0.0001 and P<0.05, P<0.001, respectively) levels were observed among controls and coke-oven workers, except for bottom coke oven workers. Associations between age and risk of increased TNF-a, smoking and increased GST activities, and drinking with increased MDA concentrations, were marginal (P=0.055, P=0.048, P=0.057, respectively). The association between smoking with MDA (P=0.004), NSE (P=0.005), SCC (P=0.004) and TNF-a (P<0.001), and drinking with TNF-a levels was significant (P=0.012). In addition, a significant positive correlation between oxidative stress and tumor markers was found in the present study. These results suggest that a synergistic increase of oxidative stress and tumor markers induced by PAHs may play a role in toxic responses for PAHs in coke oven workers.

Impact of AhR, CYP1A1 and GSTM1 genetic polymorphisms on TP53 R273G mutations in individuals exposed to polycyclic aromatic hydrocarbons

This study was to undertaken to investigate the impacts of AhR, CYP1A1, GSTM1 genetic polymorphisms on the R273G mutation in exon 8 of the tumor suppressor p53 gene (TP53) among polycyclic aromatic hydrocarbons (PAHs) exposed to coke-oven workers. One hundred thirteen workers exposed to PAH and 82 control workers were recruited. We genotyped for polymorphisms in the AhR, CYP1A1, GSTM1, and TP53 R273G mutation in blood by PCR methods, and determined the levels of 1-hydroxypyrene as PAH exposure marker in urine using the high pressure liquid chromatography assay. We found that the distribution of alcohol users and the urinary excretion of 1-OHP in the exposed workers were significantly higher than that of the control workers (p=0.004, p<0.001, respectively). Significant differences were observed in the p53 genotype distributions of smoking subjects (p=0.01, 95%CI: 1.23-6.01) and PAH exposure (p=0.008, 95%CI: 1.24-4.48), respectively. Further, significant differences were observed in the p53 exon 8 mutations for the genetic polymorphisms of Lys/Arg for AhR (p=0.02, 95%CI: 0.70-15.86), Val/Val for CYP1A1 (p=0.04, 95%CI: 0.98-19.09) and null for GSTM1 (p=0.02, 95%CI: 1.19-6.26), respectively. Our findings indicated that polymorphisms of PAH metabolic genes, such as AhR, CYP1A1, GSTM1 polymorphisms may interact with p53 genetic variants and may contribute to PAH related cancers.

Biomarkers of polycyclic aromatic hydrocarbon exposure in European coke oven workers

Biomonitoring is an excellent method for capturing the results of all exposures, regardless of route. Coke oven workers include certain groups that have the potential for high exposure to polycyclic aromatic hydrocarbons (PAH) and other materials. Biomarkers of exposure to these agents include PAH metabolites as markers of internal dose and carcinogen-DNA adducts as measure of effective dose. The purpose of this study was to determine the levels of these biomarkers in persons with different job duties in a modern coke oven plant. We report that the mean levels of 1-hydroxypyrene (1HP) and carcinogen DNA adducts in the exfoliated urothelial cells of coke oven workers are increased the closer a group of workers is to the ovens and highest in the top oven workers with average 1HP level of 11.6 μg/l and 22 adducts per 10(9) unadducted nucleotides. Both 1HP and carcinogen DNA adduct levels increased in supervisors, area workers, side oven workers, top and side oven workers, and top oven workers, respectively. These data are the first to demonstrate an increase in target organ genotoxicity in coke oven workers and a relationship with other biomarkers. Future studies will determine the identity of the DNA adducts, their correlation with 1HP levels and the relationship between levels in individual workers.

Lymphocyte oxidative stress/genotoxic effects are related to serum IgG and IgA levels in coke oven workers

We investigated oxidative stress/genotoxic effects levels, immunoglobulin levels, polycyclic aromatic hydrocarbons (PAHs) levels exposed in 126 coke oven workers and in 78 control subjects, and evaluated the association between oxidative stress/genotoxic effects levels and immunoglobulin levels. Significant differences were observed in biomarkers, including 1-hydroxypyrene levels, employment time, percentages of alcohol drinkers, MDA, 8-OHdG levels, CTL levels and CTM, MN, CA frequency, and IgG, IgA levels between the control and exposed groups. Slightly higher 1-OHP levels in smoking users were observed. For the dose-response relationship of IgG, IgA, IgM, and IgE by 1-OHP, each one percentage increase in urinary 1-OHP generates a 0.109%, 0.472%, 0.051%, and 0.067% decrease in control group and generates a 0.312%, 0.538%, 0.062%, and 0.071% decrease in exposed group, respectively. Except for age, alcohol and smoking status, IgM, and IgE, a significant correlation in urinary 1-OHP and other biomarkers in the total population was observed. Additionally, a significant negative correlation in genotoxic/oxidative damage biomarkers of MDA, 8-OH-dG, CTL levels, and immunoglobins of IgG and IgA levels, especially in coke oven workers, was found. These data suggest that oxidative stress/DNA damage induced by PAHs may play a role in toxic responses for PAHs in immunological functions.

Urinary 1-hydroxypyrene and 8-hydroxydeoxyguanosine levels among coke-oven workers for 2 consecutive days

OBJECTIVES

This study evaluated the levels of exposure to polycyclic aromatic hydrocarbons (PAHs) and their relationship with oxidative DNA damage among Vietnamese coke-oven workers.

METHODS

We collected urine from 36 coke-oven workers (exposed group) at the beginning and end of the shift on 2 consecutive days. We also collected urine from 78 medical staff (control group). Information was collected by questionnaire about smoking status, drinking habit, and working position. Urinary 1-hydroxypyrene (1-OHP) and 8-hydroxydeoxyguanosine (8-OH-dG) were measured using HPLC. All statistical analyses were performed with SPSS version 19.

RESULTS

Urinary 1-OHP was significantly higher in the coke-oven workers than in the control group (p<0.05). Top-oven workers had the highest levels of internal exposure to PAHs, followed by side-oven and then bottom-oven workers (5.41, 4.41 and 1.35 ng/mg creatinine, respectively, at the end of the shift on day 2). Urinary 8-OH-dG was significantly higher in top- and side-oven workers at the end of the shift on day 2 (4.63 and 5.88 ng/mg creatinine, respectively) than in the control group (3.85 ng/mg creatinine). Based on a multi-regression analysis, smoking status had a significant effect on urinary 8-OH-dG (p=0.049). Urinary 1-OHP tended to have a positive correlation with urinary 8-OH-dG (p=0.070).

CONCLUSIONS

Vietnamese coke-oven workers were exposed to PAHs during their work shift. Urinary 1-OHP exceeded the recommended limit, and elevated oxidative DNA damage occurred in top- and side-oven workers on the second day of work. A tendency for positive correlation was found between urinary 1-OHP and urinary 8-OH-dG.

Influence of genetic polymorphisms on biomarkers of exposure and effects in children living in Upper Silesia

This article is a follow-up to our previous molecular epidemiology studies on the DNA damage in children from the Upper Silesia region of Poland. It is expected that metabolic and DNA repair gene polymorphisms may modulate individual susceptibility to environmental exposure. In this study, we investigate the association between polymorphisms of metabolising (CYP2D, EPHX1, GSTM1, GSTP1, GSTT1, NAT2) and DNA repair (XPD, XRCC1, XRCC3) genes and selected biomarkers of exposure and effect such as levels of 1-hydroxypyrene (1-OHP) and urinary mutagenicity, aromatic DNA adducts, sister chromatid exchange (SCE) and micronuclei (MN) in 74 children. Both 1-OHP concentration and urinary mutagenicity tested by TA98+S9 were significantly higher in individuals with EPHX1 (exon 4) Arg/Arg genotype than in individuals with other genotype. The EPHX1 (exon 3) significantly affected urinary mutagenicity tested with strain YG1024+S9. The urinary mutagenicity in individuals with Tyr/Tyr homozygotes was lower than in individuals with Tyr/His and His/His (1057±685 vs. 1432±1003 revertants/mol creatinine). XRCC3 Met/Met genotype was associated with significantly higher levels of 1-OHP in urine compared with only The/Met genotype. The PAH-DNA adduct levels in the subgroup with GSTM1 null genotype was 2-fold higher than in individuals with GSTM1 active (7.06±5.12 vs. 13.14±9.81 adduct/10(8) nucleotides). The mean level of aromatic DNA adducts in children with deletion of the GSTT1 gene was significantly higher compared with individuals with that gene present (8.03±6.23 vs. 14.66±10.70 adduct/10(8) nucleotides). Also the carriers of the XPD Lys/Lys genotype showed higher levels of DNA adducts than heterozygotes (13.16±9.70 vs. 6.81±5.86 adducts/10(8) nucleotides). Children carrying the XRCC3-241 Met/Met genotype exhibited a higher number of SCE in peripheral blood lymphocytes than carriers of Thr/Met allele (8.15±0.86 vs. 7.62±0.79 SCE/cell). It was also observed that children with the GSTP1 slow conjugator had significantly elevated MN in peripheral blood lymphocytes compared with fast conjugator (4.23±3.49 vs. 6.56±5.00 MN/1000 cells).

The effect of occupational exposure to benzo[a]pyrene on neurobehavioral function in coke oven workers

BACKGROUND

Coke oven workers are regularly exposed to polycyclic aromatic hydrocarbons (PAHs). Benzo[a]pyrene (B[a]P), known as an indicator species for PAH contamination, is a neurobehavioral toxicant. The purpose of the study was to evaluate the relationship between B[a]P exposure, a B[a]P-related urinary metabolite and neurobehavioral function among coke oven workers.

METHODS

Coke oven workers and oxygen factory workers participated in this study. B[a]P exposure was monitored by air sampling pump, and urinary 1-hydroxypyrene (1-OHP) level was detected with high performance liquid chromatography (HPLC). A questionnaire and the neurobehavioral core test battery (NCTB) were administered to all subjects.

RESULTS

B[a]P-exposed workers were found to have higher urinary 1-OHP levels and worse NCTB performances on eight items than control workers. B[a]P concentrations were higher in the coke oven plant than that in the controls' workplace. The performances on simple reaction time, correct pursuit aiming, and error pursuit aiming decreased with increasing airborne B[a]P in coke oven workers. There were significant correlations between urinary 1-OHP level and six items of the NCTB.

CONCLUSIONS

Occupational exposure to B[a]P is associated with neurobehavioral function impairment in coke oven workers.

Susceptibility to DNA damage in workers occupationally exposed to pesticides, to tannery chemicals and to coal dust during mining

Our mutagenesis group has been studying with important economic drivers of our state, such as agriculture, the foot-wear and leather industry and open-cast coal mining. Working conditions in these sectors have potentially harmful to humans. The aim of these studies is to determine the health risk of workers by biomonitoring subjects exposed to genotoxic agents. The main results of our studies with vineyard farmers we observed a high rate of MN and DNA damage in individuals exposed to pesticides (p < 0.001). In addition, some effects of genetic polymorphisms in the modulation of MN results were observed in this group. Tobacco farmers were also evaluated at different crop times. The results showed a significant increase in the Damage index and frequency in tobacco farmers compared to the non-exposed group, for all crop times. The results for footwear and tannery workers showed a significant increase in the mean ID for the solvent-based adhesive (p < 0.001) group in comparison to the water-based adhesive group and control (p < 0.05). For open-cast coal mine workers, the EBCyt indicated a significant increase in nuclear bud frequency and cytokinetic defects in the exposed group compared to the non-exposed group (p < 0.0001). We were able to associate specific genetic susceptibility with each type of exposure and with the non-use or improper use of personal protection equipment and diet adequacy. These results show how important the continuous education of exposed workers is to minimizing the effect of the occupational exposure and the risk of disease associated with the work.

A novel use of neural network model to determine the effects of multibiomarker on early health damage among Chinese steel workers

Coke-oven workers are exposed to many kinds of pollutants that can cause health damage even lead to carcinogenesis. Therefore, it is critical to identify biomarkers that predict early health damage in these exposed individuals in molecular epidemiological studies. We applied an artificial neural network (ANN) model to the identification of such predictors in a study of coke-oven workers. The study included 330 steel-factory workers who were exposed to different levels of polycyclic aromatic hydrocarbons (PAHs) in the workplace and their levels of early health damage were determined by cytokinesis-block micronuclei (CMN), heat shock protein 70 (Hsp70) expression, benzo(a)pyrene diolepoxide-albumin adduct (BPDE-AA), and olive tail moment (OTM). The ANN model was built to predict the early health damage index, and the receiver operating characteristic (ROC) curve was used to illustrate the judged criteria and the ANN model. Trend Chi-square modeling was also performed. We found that there were 55 subjects with early health damage among 330 workers based on the multibiomarker criteria using the 95 percentile of the control group as the cut-off value, while there were 22-35 positive subjects if screening by any single biomarker. The Cochran-Armitage trend test for these findings were statistically significant (Z = 3.21, P = 0.0013). Six variables were selected to simulate the ANN model. The area under ROC (AUROC) was 0.726 ± 0.037 (P < 0.001), and the predictors included workplace, cholesterol, waistline, and others. Therefore, collective using CMN frequency, Hsp70 level, BPDE-AA level, and OTM with equal weights to make an initial screening test for early health damage in coke-oven workers is feasible and superior to any single biomarker. The determinants of the effects of multibiomarker on early health damage screening can be identified by the ANN model and ROC curve method.

Genetic variants of nucleotide excision repair genes are associated with DNA damage in coke oven workers

We explored the effects of single nucleotide polymorphisms (SNP) of nucleotide excision repair (NER) genes on DNA damage caused by exposure to carcinogenic polycyclic aromatic hydrocarbons (PAH) in 475 Chinese workers. We quantified urinary 1-hydroxypyrene using high-performance liquid chromatography, and the DNA damage level of lymphocytes was examined by the comet assay and represented as the Olive tail moment (OTM) value. We genotyped 38 tagSNPs in 10 NER genes. The SNP function was further investigated using luciferase reporter assay in three cell lines. Our results showed that two promoter SNPs, XPA rs1800975 and XPC rs3731055, were associated with lower OTM values (P(trend) = 0.01 and 0.02 respectively). However, another missense SNP rs2228001 in the XPC gene was positively associated with OTM value (P(trend) = 0.01). A stratified analysis found that the association between this SNP and DNA damage was only observed among subjects with higher PAH exposure levels but not among those with lower exposure levels (P(interaction) = 0.018). A dose-response association was found between the combined risk alleles of the above three genetic variants and increased DNA damage levels (P(trend) = 0.004). This association was more pronounced in subjects with higher PAH exposure than those with lower exposure levels (P(interaction) = 0.046). Our functional study indicated that XPA rs1800975G and XPC rs3731055A alleles had a higher luciferase expression than their corresponding SNP alleles (P < 0.05). These results suggested that genetic variations in key NER genes, especially in XPA and XPC genes, may modulate DNA damage levels when exposed to PAHs.

Shorter telomere length in peripheral blood lymphocytes of workers exposed to polycyclic aromatic hydrocarbons

Shorter telomere length (TL) in peripheral blood lymphocytes (PBLs) is predictive of lung cancer risk. Polycyclic aromatic hydrocarbons (PAHs) are established lung carcinogens that cause chromosome instability. Whether PAH exposure and its molecular effects are linked with shorter TL has never been evaluated. In the present study, we investigated the effect of chronic exposure to PAHs on TL measured in PBLs of Polish male non-current smoking cokeoven workers and matched controls. PAH exposure and molecular effects were characterized using measures of internal dose (urinary 1-pyrenol), effective dose [anti-benzo[a]pyrene diolepoxide (anti-BPDE)-DNA adduct], genetic instability (micronuclei, MN) and DNA methylation [p53 promoter and Alu and long interspersed nuclear element-1 (LINE-1) repetitive elements, as surrogate measures of global methylation] in PBLs. TL was measured by real-time polymerase chain reaction. Cokeoven workers were heavily exposed to PAHs (79% exceeded the urinary 1-pyrenol biological exposure index) and exhibited lower TL (P = 0.038) than controls, as well as higher levels of genetic and chromosomal alterations [i.e. anti-BPDE-DNA adduct and MN (P < 0.0001)] and epigenetic changes [i.e. p53 gene-specific promoter and global methylation (P <or= 0.001)]. TL decreased with longer duration of work as cokeoven worker (P = 0.039) and in all subjects with higher levels of anti-BPDE-DNA adduct (P = 0.042), p53 hypomethylation (P = 0.005) and MN (P = 0.009). In multivariate analysis, years of work in cokery (P = 0.008) and p53 hypomethylation (P = 0.001) were the principal determinants of shorter TL. Our results indicate that shorter TL is associated with chronic PAH exposure. The interrelations with other genetic and epigenetic mechanisms in our data suggest that shorter TL could be a central event in PAH carcinogenesis.

Global and gene-specific promoter methylation changes are related to anti-B[a]PDE-DNA adduct levels and influence micronuclei levels in polycyclic aromatic hydrocarbon-exposed individuals

We investigated the effect of chronic exposure to polycyclic aromatic hydrocarbons (PAHs) on DNA methylation states (percentage of methylated cytosines (%mC)) in Polish male nonsmoking coke-oven workers and matched controls. Methylation states of gene-specific promoters (p53, p16, HIC1 and IL-6) and of Alu and LINE-1 repetitive elements, as surrogate measures of global methylation, were quantified by pyrosequencing in peripheral blood lymphocytes (PBLs). DNA methylation was evaluated in relation to PAH exposure, assessed by urinary 1-pyrenol and anti-benzo[a]pyrene diolepoxide (anti-B[a]PDE)-DNA adduct levels, a critical genetic damage from B[a]P. We also evaluated whether PAH-induced DNA methylation states were in turn associated with micronuclei in PBLs, an indicator of chromosomal instability.

PAH biomarkers for human health risk assessment: a review of the state-of-the-art

Polycyclic aromatic hydrocarbons (PAH) are widely distributed in the environment, and some are carcinogenic to human beings. The study of biomarkers has helped clarify the nature and magnitude of the human health risks posed by such substances. This article provides a review of the state-of-the-art on PAH biomarkers for human health risk assessment and also discusses their applicability within the context of environmental management in Brazil. The article discusses the methodologies for determination of some biomarkers such as 1-hydroxypyrene and PAH-DNA adducts. Cytogenetic markers, frequency of chromosomal aberrations, and micronucleus induction were considered for the evaluation of cancer risk. The current stage of studies on validation of such biomarkers was also approached.

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.

Micronuclei related to anti-B[a]PDE-DNA adduct in peripheral blood lymphocytes of heavily polycyclic aromatic hydrocarbon-exposed nonsmoking coke-oven workers and controls

Micronuclei (MN) frequency associated to biologically effective dose of polycyclic aromatic hydrocarbons [PAH; anti-benzo[a]pyrene diolepoxide (B[a]PDE)-DNA] within the same subjects' peripheral blood lymphocytes (PBL) was evaluated. Study subjects were nonsmoking male Polish coke-oven workers (n=49) and matched controls (n=45) verified for PAH exposure by urinary 1-pyrenol. We found that coke-oven workers, heavily exposed to PAHs (80% workers exceeded the urinary 1-pyrenol biological exposure index value), presented significantly higher MN frequency in PBLs than controls (P<0.01). Substantial difference was also found for adduct levels in PBLs (P<0.01). Increase in MN levels was significantly related to anti-B[a]PDE-DNA formation, key adduct of the ultimate carcinogenic metabolite of B[a]P (n=94; r=0.47; P<0.001). The dose-response relationship was improved when subjects with adduct levels above the 3rd tertile (>or=4.35 adducts/10(8) nucleotides) were excluded (n=61; r=0.69; P<0.001). Saturation of adduct/MN formation at high levels may disturb the underlying relationship. Linear multiple regression analysis, without subjects of 3rd tertile adduct level (n=61), revealed that adduct formation (t=4.61; P<0.001), but not 1-pyrenol, was the significant determinant in increasing MN. In conclusion, the increase in MN frequency is mainly related to the specific anti-B[a]PDE-DNA formation within PBLs of the same subject. Our results substantiate, with the use of an early indicator of biological effect as well, that workers are at higher cancer risk than controls.

Using lymphocyte and plasma Hsp70 as biomarkers for assessing coke oven exposure among steel workers

BACKGROUND

Hsp70, an early-response protein induced when organisms are confronted with simple or complicated environmental stresses, can act as either a cellular protector or a danger signal.

OBJECTIVES

The goal of this study was to evaluate levels of lymphocyte and/or plasma Hsp70 as biomarkers for assessing exposure response to complex coke oven emissions (COEs).

METHODS

We recruited 101 coke oven workers and determined levels of polycyclic aromatic hydrocarbon (PAH) exposure, urinary 1-hydroxypyrene (1-OHP), genotoxic damage by comet assay and micronuclei test, and other markers of damage, including plasma malondialdehyde (MDA) and lactate dehydrogenase (LDH). These were compared to levels of lymphocyte (intra-cellular) and plasma (extracellular) Hsp70 using Western blots and enzyme-linked immunosorbent assays (ELISA), respectively.

RESULTS

We observed a COEs-related dose-dependent increase in levels of DNA damage, micronuclei rate, MDA concentration, and LDH activity. Lymphocyte Hsp70 levels increased in the intermediate-exposure group (1.39 +/- 0.88) but decreased in the high-exposure group (1.10 +/- 0.55), compared with the low-exposure group. In contrast, plasma Hsp70 levels progressively increased as the dose of exposure increased. Negative correlations were seen between lymphocyte Hsp70 levels and olive tail moment and LDH activity in the intermediate- and high-exposure groups. However, we observed positive correlations between plasma Hsp70 levels and LDH activity in the low and intermediate groups.

CONCLUSIONS

In workers exposed to COEs, high lymphocyte Hsp70 levels may provide protection and high plasma Hsp70 levels may serve as a danger marker. Larger validation studies are needed to establish the utility of Hsp70 as a response marker.

Association between plasma BPDE-Alb adduct concentrations and DNA damage of peripheral blood lymphocytes among coke oven workers

OBJECTIVES

Coke oven emissions (COE) containing polycyclic aromatic hydrocarbons (PAHs) can induce both benzo[a]pyrene-r-7, t-8, t-9,c-10-tetrahydotetrol-albumin (BPDE-Alb) adducts and DNA damage. However, the relation between these biomarkers for early biological effects is not well documented in coke oven workers.

METHODS

In this study, the authors recruited 207 male workers exposed to COE and 102 controls not exposed to COE in the same steel plant in northern China. They measured BPDE-Alb adduct concentrations in plasma with reverse-phase high performance liquid chromatography and DNA damage in peripheral blood lymphocytes with alkaline comet assay.

RESULTS

The results showed that the median concentration of BPDE-Alb adducts in the exposed group (34.36 fmol/mg albumin) was significantly higher than that in the control group (21.90 fmol/mg albumin, p = 0.012). The mean Olive tail moment (Olive TM) of DNA damage in the exposed and control groups were 1.20 and 0.63, respectively (p = 0.000). Multivariate logistic regression analysis revealed that the odds ratio (OR) for BPDE-Alb adduct and Olive TM associated with the exposure were 1.72 (95% CI 1.06 to 2.81) and 1.96 (95% CI 1.20 to 3.19), respectively. These results show significant correlations between the concentrations of BPDE-Alb adduct and Olive TM levels in exposed group (r = 0.235, p = 0.001) but not in control group (r = 0.093, p = 0.353).

CONCLUSION

The results suggest that occupational exposure to COE may induce both BPDE-Alb adducts and DNA damage in the lymphocytes of coke oven workers and that these two markers are useful for monitoring exposure to COE in the workplace.

Primary DNA damage and genetic polymorphisms for CYP1A1, EPHX and GSTM1 in workers at a graphite electrode manufacturing plant

Background

The results of a cross-sectional study aimed to evaluate whether genetic polymorphisms (biomarkers of susceptibility) for CYP1A1, EPHX and GSTM1 genes that affect polycyclic aromatic hydrocarbons (PAH) activation and detoxification might influence the extent of primary DNA damage (biomarker of biologically effective dose) in PAH exposed workers are presented. PAH-exposure of the study populations was assessed by determining the concentration of 1-hydroxypyrene (1OHP) in urine samples (biomarker of exposure dose).

Methods

The exposed group consisted of workers (n = 109) at a graphite electrode manufacturing plant, occupationally exposed to PAH. Urinary 1OHP was measured by HPLC. Primary DNA damage was evaluated by the alkaline comet assay in peripheral blood leukocytes. Genetic polymorphisms for CYP1A1, EPHX and GSTM1 were determined by PCR or PCR/RFLP analysis.

Results

1OHP and primary DNA damage were significantly higher in electrode workers compared to reference subjects. Moreover, categorization of subjects as normal or outlier highlighted an increased genotoxic risk OR = 2.59 (CI95% 1.32–5.05) associated to exposure to PAH. Polymorphisms in EPHX exons 3 and 4 was associated to higher urinary concentrations of 1OHP, whereas none of the genotypes analyzed (CYP1A1, EPHX, and GSTM1) had any significant influence on primary DNA damage as evaluated by the comet assay.

Conclusion

The outcomes of the present study show that molecular epidemiology approaches (i.e. cross-sectional studies of genotoxicity biomarkers) can play a role in identifying common genetic risk factors, also attempting to associate the effects with measured exposure data. Moreover, categorization of subjects as normal or outlier allowed the evaluation of the association between occupational exposure to PAH and DNA damage highlighting an increased genotoxic risk.

The influence of metabolic gene polymorphisms on urinary 1-hydroxypyrene concentrations in Chinese coke oven workers

Urinary 1-hydroxypyrene (1-OHP), a biomarker of polycyclic aromatic hydrocarbons (PAHs) exposure, may be influenced by metabolic gene polymorphisms. Such knowledge could benefit us in understanding the inter-individual difference in the mechanism of PAHs-induced carcinogenesis. We investigated the influence of gene polymorphisms on urinary 1-OHP concentrations in 447 coke oven workers from two coking plants in south China. After adjustment for age, plant, level of occupational exposure, body mass index, level of education, alcohol consumption, cigarette smoking and respirator usage, AhR R554K (rs2066853), UGT1A1 -3263T>G (rs4124874) and GSTP1 I105V (rs1695) were associated with urinary 1-OHP excretion with the p-value of 0.053, 0.006 and 0.021, respectively. The concentrations of urinary 1-OHP (Geometric mean, micromol/mol creatinine) in the homozygous major variant carriers and homozygous minor variant carriers for AhR R554K, UGT1A1 -3263T>G and GSTP1 I105V were listed as follows: 4.20 and 5.12, 5.11 and 3.92, 4.93 and 2.91, respectively. GSTT1 present carriers had a significantly higher urinary 1-OHP level than that in null carriers in the case with AhR R554K GA/AA carriers (5.17 vs. 3.64 micromol/mol creatinine, p=0.038), as well as in the case with UGT1A1 -3263T>G TG/GG carriers (5.67 vs. 3.38 micromol/mol creatinine, p=0.001). These results showed that AhR, UGT1A1, GSTP1 and GSTT1 polymorphisms were associated with urinary 1-OHP concentrations in Chinese coke oven workers. No influence was found in the association between urinary 1-OHP and other genetic polymorphisms such as CYP1A1, CYP1A2, CYP1B1, CYP2E1, EPHX1, EPHX2 in this population.

Path Analysis of Biomarkers of Exposure and Early Biological Effects among Coke-Oven Workers Exposed to Polycyclic Aromatic Hydrocarbons

Many host factors or biomarkers are involved in the process of early DNA damage induced by occupational exposure to polycyclic aromatic hydrocarbons (PAH) as seen in coke-oven workers. This paper aimed to identify complicated causal interrelationship of various biomarkers using the path analysis. In this analysis, we included 235 subjects (166 coke-oven workers and 69 nonexposed controls) whose data on the comet assay (e.g., Olive tail moment) and cytogenetic analysis of peripheral blood lymphocytes as well as urinary 1-hydroxypyrene (1-OHP) were available. The path analysis showed that coke-oven exposure and tobacco smoke were both significant predictors of the concentrations of urinary 1-OHP (P < 0.05), with a coefficient of determination of 0.75. The factors having significant influence on the Olive tail moment were in the following order: urinary 1-OHP > XRCC1-exon 9 variant genotype > ERCC2-exon 10 variant genotype > XRCC1-exon 6 variant genotype, with a coefficient of determination of 0.22. The variables of relative importance in influencing on cytokinesis-block micronucleus frequencies were in the following order: coke-oven exposure > urinary 1-OHP > age > mEH3 variant genotype > ERCC2-exon 10 variant genotype > XRCC1-exon 6 variant genotype, with a coefficient of determination of 0.27. These results indicated that exogenous agents, especially the coke-oven exposure, played a more important role than the genotypes in the induction of early genetic damage. In conclusion, the path analysis seemed to be an alternative statistical approach for the ascertainment of complicated association among related biomarkers for the assessment of occupational exposure.