The polymorphisms in cGAS-STING pathway are associated with mitochondrial DNA copy number in coke oven workers

OBJECTIVE

To evaluate the interaction effects of Polycyclic aromatic hydrocarbons (PAHs) exposure and variants in cGAS-STING genes on mitochondrial DNA copy number (mtDNAcn) in workers.

METHODS

The mtDNAcn was determined by real-time quantitative polymerase-chain reaction in 544 PAHs-exposed workers and 238 office workers. The polymorphisms were detected by flight mass spectrometry.

RESULTS

The mtDNAcn in PAHs exposure group was significantly lower than non-occupational exposure population (P < 0.00). The cGAS rs610913 CA+AA had significant interaction effects with STING rs11554776 GG+GA (P = 0.035), rs7380824 CC+CT (P = 0.026), and rs78233829 GC+CC (P = 0.034) on mtDNAcn. The generalized linear model results showed that the influencing factors of mtDNAcn include PAHs exposure (P < 0.001) and the interaction of PAHs exposure and cGAS rs 311678 AA+AG (P = 0.047).

CONCLUSION

The influencing factors of mtDNAcn include PAHs exposure and the interaction of PAHs exposure and cGAS rs 311678 AA+AG.

Association of Genetic Polymorphisms of TERT with Telomere Length in Coke Oven Emissions-Exposed Workers

We explored the association between variations in the telomere maintenance genes and change in telomere length (TL) in workers. The TL of peripheral blood leukocytes from 544 coke oven workers and 238 controls were detected using the Real-time PCR method. Variations in four genes were then detected using the PCR based restriction fragment length polymorphism. The effects of environmental and genetic factors on TL were subsequently analyzed through covariance analysis and a generalized linear model .The TL of subjects with GG genotypes were longer than those with AG genotype in the TERT rs2736098 locus amongst the controls (P = .032). The combined effect of COEs exposure and AG+AA genotypes had a significant effect on TL (P < .001). The interaction between the COEs exposure factor and the rs2736098AG+AA genotypes had a significant effect on the TL (P < .05). The TL in coke oven workers is associated with the interactions between TERT rs2736098 AG+AA and COEs exposure.

Effect and interaction of TNKS genetic polymorphisms and environmental factors on telomere damage in COEs-exposure workers

Coke oven emissions (COEs) contain many carcinogenic polycyclic aromatic hydrocarbons (PAHs). Telomere damage is an early biological marker reflecting long-term COEs-exposure. Whereas, whether the genetic variations of telomere-regulated gene TNKS have an effect on the COEs-induced telomere damage is unknown. So we detected the environmental exposure levels, relative telomere length (RTL), and TNKS genetic polymorphisms among 544 COEs-exposure workers and 238 healthy participants. We found that the RTL of the wild homozygous GG genotype in rs1055328 locus was statistically shorter compared with the CG+CC genotype for the healthy participants using covariance analysis(P = 0.008). In the Generalized linear model (GLM) analysis, TNKS rs1055328 GG could accelerate telomere shortening (P = 0.011); and the interaction between TNKS rs1055328 GG and COEs-exposure had an effect on RTL (P = 0.002). In conclusion, this study was the first to discover the role of TNKS rs1055328 locus in COEs-induced telomere damage, and proved that chromosomal damage was a combined consequence of environmental and genetic factors.

The interaction effects of secondhand smoke exposure and overweight on the prevalence of hypertension in Chinese coke oven workers and NHANES participants (2013-2016)

BACKGROUND

The prevalence of hypertension may be affected by environmental pollution and personal behavior.

OBJECTIVES

We aimed to evaluate the interaction effects of secondhand smoke exposure and overweight on hypertension.

METHODS

In this cross-sectional study, a total of 627 workers from a coking plant in China and 1011 individuals from the NHANES database in the United States from 2013 to 2016 were selected as the research participants. The concentrations of 11 urinary polycyclic aromatic hydrocarbons (PAHs) metabolites and 3 tobacco metabolites were measured. An interaction effect was tested in the modified Poisson regression models.

RESULTS

For smokers among Chinese coke oven workers, the only statistically significant positive association was with hypertension in the highest tertile of nicotine metabolized ratio (NMR) (PR: 1.539, 95% CI: 1.013-2.337). Nonsmoking Chinese workers with 3rd tertile urinary nicotine levels were associated with a 114.8% significantly increased prevalence of hypertension (PR: 2.148, 95% CI: 1.025-4.500) compared to nonsmokers 1st tertile with nicotine levels. Association between tobacco exposure and hypertension is possibly modified by PAHs exposure (PR: 2.335, 95% CI: 0.933-5.841). Nonsmokers in the NHANES database with high urinary nicotine levels were associated with a 17.3% significantly increased prevalence of hypertension (PR: 1.173, 95% CI: 1.028-1.338) compared to those with low nicotine levels. We observed that overweight people with high nicotine levels had a significantly higher likelihood of hypertension than no overweight people with low nicotine levels among nonsmoking Chinese coke oven workers and NHANES participants (PR = 4.686, 95% CI: 1.488-14.754; PR = 1.251, 95% CI: 1.039-1.506).

CONCLUSIONS

Tobacco exposure and overweight are important risk factors for hypertension, and secondhand smoke exposure and overweight have an interactive effect on the incidence of hypertension in nonsmoking Chinese coke oven workers and NHANES participants.

Joint effects of polycyclic aromatic hydrocarbons, smoking, and XPC polymorphisms on damage in exon 2 of KRAS gene among young coke oven workers

Genetic polymorphisms may contribute to individual susceptibility to DNA damage induced by environmental exposure. In this study, we evaluate the effects of co-exposure to PAHs, smoking and XPC polymorphisms, alone or combined, on damage in exons. A total of 288 healthy male coke oven workers were enrolled into this study, and urinary 1-hydroxypyrene (1-OH-Pyr) was detected. Base modification in exons of KRAS and BRAF gene, and polymorphisms of XPC were determined in plasma by real-time PCR. We observed 1-OH-Pyr was positively related to damage in exon 2 of KRAS (KRAS-2) and in exon 15 of BRAF (BRAF-15), respectively, and KRAS-2 and BRAF-15 were significantly associated with increased 1-OH-Pyr. A stratified analysis found 1-OH-Pyr was significantly associated with KRAS-2 in both smokers and non-smokers, while 1-OH-Pyr was significantly associated with BRAF-15 only in smokers. Additionally, individuals carrying both rs2228001 G-allele (GG+GT) and rs3731055 GG homozygote (GG) genotype appeared to have more significant effect on KRAS-2. The high levels of 1-OH-Pyr were associated with KRAS-2 only in rs2228001 GG+GT genotype carriers and the high levels of 1-OH-Pyr were associated with KRAS-2 only in rs3731055 GG genotype carriers and the most severe KRAS-2 was observed among subjects carrying all four of the above risk factors. Our findings indicated the co-exposure effect of PAHs and smoking could increase the risk of KRAS-2 by a mechanism partly involving XPC polymorphisms.

The interaction effects of FEN1 rs174538 polymorphism and polycyclic aromatic hydrocarbon exposure on damage in exon 19 and 21 of EGFR gene in coke oven workers

Polycyclic aromatic hydrocarbon (PAH) exposure and genetic susceptibility were conductive to genotoxic effects including gene damage, which can increase mutational probability. We aimed to explore the dose-effect associations of PAH exposure with damage of exons of epidermal growth factor receptor (EGFR) and breast cancer susceptibility gene 1 (BRCA1), as well as their associations whether modified by Flap endonuclease 1 (FEN1) genotype. Two hundred eighty-eight coke oven male workers were recruited, and we detected the concentration of 1-hydroxypyrene (1-OH-pyr) as PAH exposure biomarker in urine and examined base modification in exons of EGFR and BRCA1 respectively, and genotyped FEN1 rs174538 polymorphism in plasma. We found that the damage indexes of exon 19 and 21 of EGFR (EGFR-19 and EGFR-21) were both significantly associated with increased urinary 1-OH-pyr (both P_trend < 0.001). The levels of urinary 1-OH-pyr were both significantly associated with increased EGFR-19 and EGFR-21 in both smokers and nonsmokers (both P < 0.001). Additionally, we observed that the urinary 1-OH-pyr concentrations were linearly associated with both EGFR-19 and EGFR-21 only in rs174538 GA+AA genotype carriers (both P < 0.001). Moreover, FEN1rs rs174538 showed modifying effects on the associations of urinary 1-OH-pyr with EGFR-19 and EGFR-21 (both P_interaction < 0.05). Our findings revealed the linear dose-effect association between exon damage of EGFR and PAH exposure and highlight differences in genetic contributions to exon damage and have the potential to identify at-risk subpopulations who are susceptible to adverse health effects induced by PAH exposure.

Desorption process and morphological analysis of real polycyclic aromatic hydrocarbons contaminated soil by the heterogemini surfactant and its mixed systems

Surfactant-enhanced remediation (SER) is an efficient and low-cost technology for polycyclic aromatic hydrocarbons (PAHs) contaminated sites. This study assessed the desorption processes and effects of Heterogemini surfactant (Dodecyldimethylammonium bromide/tetradecyldimethylammonium bromide, DBTB), two traditional surfactants (Hexadecyl trimethyl ammonium bromide, CTAB; Sorbitan monolaurate, Span 20) and their mixed systems on the real PAHs-contaminated soil from an abandoned coking plant, as well they were analyzed micro morphologically. DBTB had greater desorption capability for PAHs and favorable interaction with the traditional surfactants confirmed by reaction parameters β^m and Gibbs. Whether for total PAHs (TPAHs) or different molecular weight PAHs, the mixed system Span 20/DBTB had larger molar solubilization ratio (MSR) and partition coefficient (K_m) than CTAB/DBTB, the highest desorption rate for TPAHs reaching 68.83%. Additionally, microscopic morphology showed micelles of Span 20/DBTB were more dispersed and formed strings easily, explaining its good desorption capability. What resulted demonstrated the feasibility of DBTB, a novel Heterogemini surfactant, and its mixed systems remediating PAHs-contaminated soil of abandoned industrial site.

Heart rate variability mediates the association between polycyclic aromatic hydrocarbons exposure and atherosclerotic cardiovascular disease risk in coke oven workers

Polycyclic aromatic hydrocarbons (PAHs) metabolites was related to heart rate variability (HRV) reduction and atherosclerotic cardiovascular disease (ASCVD), and ASCVD was also affected by HRV. However, the mediating role of HRV in the association between PAHs exposure and ASCVD risk was largely unknown. We aimed to investigate whether the relation of PAHs exposure with ASCVD risk was mediated by HRV among coke oven workers. A total of 1100 subjects with complete data were qualified in the current study. We measured 12 urinary PAHs metabolites by gas chromatography-mass spectrometry (GC-MS) and HRV indices by 3-channel digital Holter monitors. The associations between urinary PAHs metabolites, HRV indices, and ASCVD risk were explored using generalized linear models or multivariate logistic regression models. A mediation analysis was conducted to examine the role of HRV on the association between PAHs exposure and ASCVD risk. We found that urinary 1-hydroxynaphthalene (1-OHNa), 2-OHNa, and total PAH metabolites (ΣOH-PAH) were dose-responsive associated with increased risk of ASCVD. Compared with lowest quartile, the adjusted odds ratio (OR) for ASCVD risk in the highest quartile were 2.36 for 1-OHNa, 6.58 for 2-OHNa, and 1.60 for ΣOH-PAH (all P_trend<0.05). In addition, significant dose-dependent relationships were found across 2-OHNa quartiles with decreasing HRV indices, which in turn, were positively associated with elevated risk of ASCVD (all P_trend<0.05). Mediation analyses indicated that HRV mediate 2.7%-4.3% of the association between 2-OHNa exposure and higher ASCVD risk. Our data suggested that occupational exposure to PAHs may increase ASCVD risk, which was partially mediated by HRV.

Association of polycyclic aromatic hydrocarbons metabolites and risk of diabetes in coke oven workers

Elevated polycyclic aromatic hydrocarbons (PAHs) metabolites have recently been linked to increased risk of diabetes in the general population, but little is known about the risk of diabetes due to high pollution levels of PAHs exposure. We aimed to examine whether occupational exposure to PAHs would be one of the important risk factors for diabetes in the coke oven workers. A total of 1472 coke oven workers with complete data were qualified for the present study. We measured 12 urinary monohydroxy polycyclic aromatic hydrocarbons (OH-PAHs) by gas chromatography-mass spectrometry (GC-MS). Multiple logistic regression was used to evaluate the associations between urinary OH-PAHs and risk of diabetes, with adjustment for the potential confounders. We found that elevated urinary 4-hydroxyphenanthrene (4-OHPh) was significantly associated, in a dose-dependent manner, with increased risk of diabetes (P_trend = 0.003). Compared with individuals with 4-OHPh in the lowest quartile, the adjusted odds ratio (OR) of diabetes among those in the highest quartile was 2.80 (95% CI = 1.37-5.71). In stratified analysis, the association was more prominent in those who were smokers, overweight (BMI ≥24 kg/m²), with longer working years (≥20 years) and worked at coke oven settings. In addition, high levels of 4-OHPh combined with longer working years or overweight had a joint effect on the risk of diabetes. Our data suggested that elevated 4-OHPh was dose-responsive associated with increased risk of diabetes in the coke oven workers. The risk assessment of diabetes related to occupational PAHs exposure should take working years and BMI into consideration.

[Health risk assessment of coke oven PAHs emissions]

Polycyclic aromatic hydrocarbons (PAHs) produced by coke oven are with strong toxicity and carcinogenicity. Taken typical coke oven of iron and steel enterprises as the case study, the dispersion and migration of 13 kinds of PAHs emitted from coke oven were analyzed using AERMOD dispersion model, the carcinogenic and non-carcinogenic risks at the receptors within the modeling domain were evaluated using BREEZE Risk Analyst and the Human Health Risk Assessment Protocol for Hazardous Waste Combustion (HHRAP) was followed, the health risks caused by PAHs emission from coke oven were quantitatively evaluated. The results indicated that attention should be paid to the non-carcinogenic risk of naphthalene emission (the maximum value was 0.97). The carcinogenic risks of each single pollutant were all below 1.0E-06, while the maximum value of total carcinogenic risk was 2.65E-06, which may have some influence on the health of local residents.

[Hypermethylation of O(6)-methylguanine-DNA methyltransferase in human bronchial epithelial cell induced by organic extracts of coke oven emissions]

OBJECTIVE

To elucidate the mechanism of carcinogenesis induced by coke oven emissions by investigating the cell genetic damage index and the methylation of O⁶-methylguanine-DNA methyltransferase (MGMT).

METHODS

The human bronchial epithelial cell 16HBE was treated by 1 µmol/L B(a)P for 48 h, and then was exposed continuously to either 1‰ dimethyl sulfoxide (DMSO) or organic extracts of coke oven emission (OE-COE) for five days at the concentrations of 0, 2.5, 5.0, 10.0 and 20.0 µg/ml. The methylation-specific PCR (MSP-PCR), RT-PCR and immunoblotting were applied to detect the methylation status, changes of mRNA and protein of MGMT, respectively. Single cell gel electrophoresis was used to detect DNA damage induced by OE-COE.

RESULTS

Compared with the control group (DMSO), there was a significant hypermethylation in all study groups, along with the suppression of mRNA and protein in a dose-dependent manner, and the gradation ratio of them was 1.0, 0.96, 0.96, 0.85, 0.32 and 1.0, 1.0, 1.1, 0.41, 0.52, separately. There was a significant DNA damage with a dose-effect relationship in all study groups (F = 41.22, P < 0.05), and the comet Olive tail moment was (2.98 ± 1.43), (4.76 ± 1.79), (10.09 ± 1.75), (11.38 ± 1.77), (11.67 ± 1.88). The further study found that the index of DNA damage was negatively correlated to the expression of MGMT mRNA and its protein.

CONCLUSION

The DNA damage induced by COE might be associated with the suppression of MGMT caused by its hypermethylation.

[Impact of atmospheric by-product-coking emission on malignancy morbidity]

A statistically significant direct strong correlation was found and an interval was determined between the annual volumes of atmospheric emission from OAO "KOKS" and the standardized (lung, gastric, skin, thyroid, breast, and ovarian) malignancy morbidity rates in Kemerovo. There were gender differences in the incidence of malignancies. The calculated regression coefficients can predict a probable rise in malignancy morbidity in Kemerovo from 2010 due to the increased volumes of atmospheric emission by OAO "KOKS since 2001.

[Effect of coking oven emissions on level of serum oxidation-reduction and peripheral white blood cellular ras P21 and P53 in coke oven workers]

OBJECTIVE

To explore the adverse effects of coking oven emissions (COE) on the serum oxidation-reduction and relevant genes in the exposed workers.

METHODS

Fifty-six coke oven workers and forty controls were investigated. Serum Malondialdehyde (MDA) levels and the activities of total superoxide dismutases (T-SOD) were measured by spectrophotometrical method. Immunohistochemical method was used to assess the P21 and P53 levels in peripheral white blood cells.

RESULTS

Compared with controls, the individuals exposed to COE had significantly increased levels of serum MDA [(5.30 +/- 2.29) nmol/mL, P < 0.01] and markedly decreased levels of T-SOD [(100.04 +/- 10.75) NU/mL]. Additionally, the median levels of P53 and P21 were markedly increased in the exposed individuals compared with the controls (21.4% and 23.2%, respectively, all P < 0.05).

CONCLUSION

The findings indicate that occupational exposure to COE causes the rise of serum oxidation-reduction MDA and the fall of T-SOD, and increasing expression levels of P21 and P53 proteins before the occurrence of apparent clinical symptoms.

[Relationship between the expression of heat shock protein and genetic damage in peripheral blood of workers exposed to coke oven emissions]

OBJECTIVE

To explore the relationship between the expression of heat shock protein 90, 60 and 27 (HSP90, HSP60 and HSP27) and genetic damage in peripheral blood of workers exposed to coke oven emissions.

METHODS

288 coke oven workers in a steel factory were divided into the high-dose group and the low-dose group on the basis of environment monitoring result and work place. There were 172 men in high-dose group (workers who worked at the oven top and oven side) and 116 men in low-dose group (workers who worked at the oven bottom and others who were engaged to aided work). 38 workers unexposed occupationally to carcinogenic substances were selected as the control group, who were employed in medical therapy unit nearby 2 kilometers from the steel factory. Their general information, history of personal and occupational exposure, and the work environment were investigated. Blood samples were collected immediately after a shift at the end of a working day from 288 coke oven workers and 38 control workers. Levels of HSP90, HSP60 and HSP27 in peripheral blood lymphocytes were measured by Western blot, and the degree of DNA damage was detected by the comet assay.

RESULTS

Levels of HSP90 in peripheral blood lymphocytes in three groups were 0.24 +/- 0.32, 0.12 +/- 0.30 and 0.06 +/- 0.33 respectively. They increased significantly compared with that of the control. But levels of HSP60 and HSP27 were not significantly different among those groups. Compared with the control group, there was significant difference in tail length, olive tail moment et al of SCGE (G +/- s(G)) of occupational exposure workers. High-dose group > low-dose group > control group (P < 0.05). The degree of DNA damage increased with the rise of exposure BaP dose (Spearman r = -0.345, P < 0.01).

CONCLUSION

Levels of HSP90 in peripheral blood lymphocytes and the degree of DNA damage increase with the rise of exposure polycyclic aromatic hydrocarbons (PAHs) dose.

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.

Urinary 1-hydroxypyrene concentrations in Chinese coke oven workers relative to job category, respirator usage, and cigarette smoking

BACKGROUND

1-Hydroxypyrene (1-OHP) is a biomarker of recent exposure to polycyclic aromatic hydrocarbons (PAHs). We investigated whether urinary 1-OHP concentrations in Chinese coke oven workers (COWs) are modulated by job category, respirator usage, and cigarette smoking.

METHODS

The present cross-sectional study measured urinary 1-OHP concentrations in 197 COWs from Coking plant I and 250 COWs from Coking plant II, as well as 220 unexposed referents from Control plant I and 56 referents from Control plant II.

RESULTS

Urinary 1-OHP concentrations (geometric mean, micromol/mol creatinine) were 5.18 and 4.21 in workers from Coking plants I and II, respectively. The highest 1-OHP levels in urine were found among topside workers including lidmen, tar chasers, and whistlers. Benchmen had higher 1-OHP levels than other workers at the sideoven. Above 75% of the COWs exceeded the recommended occupational exposure limit of 2.3 micromol/mol creatinine. Respirator usage and increased body mass index (BMI) slightly reduced 1-OHP levels in COWs (P < 0.1). Cigarette smoking significantly increased urinary 1-OHP levels in unexposed referents (P < 0.005), but had no effect in COWs (P > 0.1).

CONCLUSIONS

Chinese COWs, especially topside workers and benchmen, are exposed to high levels of PAHs. Urinary 1-OHP concentrations appear to be modulated by respirator usage and BMI in COWs, as well as by smoking in unexposed referents.

Significant positive correlation of plasma BPDE-albumin adducts to urinary 1-hydroxypyrene in coke oven workers

OBJECTIVE

To investigate the application of BPDE-albumin adducts as monitoring biomarkers for coke oven workers exposed to polycyclic aromatic hydrocarbons (PAHs) and to explore possible relationship between BPDE-albumin adducts and urinary 1-hydroxypyrene (1-OHP) levels in them.

METHODS

Thirty-seven coke oven workers from a coke plant and 47 controls without the occupational exposure to PAHs were recruited in this study. The levels of plasma BPDE-albumin adducts and urinary 1-OHP were analyzed using high performance liquid chromatography.

RESULTS

The median levels of BPDE-albumin adducts (42.10 fmol/mg albumin) and urinary 1-OHP (5.46 micromol/mol creatinine) were significantly higher in coke oven workers than in controls (14.16 fmol/mg albumin, 2.96 micromol/mol creatinine, respectively; P<0.01). Multiple logistic regression analysis showed that coke oven workers were at higher risk of having BPDE-albumin adduct levels above 25.30 micromol/mg albumin (OR=1.79, P<0.01) and urinary 1-OHP levels above 4.13 micromol/mol creatinine (OR=2.45, P<0.05). There was a positive correlation between the levels of BPDE-albumin adducts and urinary 1-OHP in all subjects (rs=0.349, P<0.01).

CONCLUSION

BPDE-albumin adduct is a useful biomarker for monitoring long-term exposure to PAHs, and plasma BPDE-albumin adducts level is significantly correlated to urinary 1-OHP levels in coke oven workers.

Occupational exposures to polycyclic aromatic hydrocarbons, and respiratory and urinary tract cancers: a quantitative review to 2005

BACKGROUND

Exposure to polycyclic aromatic hydrocarbons (PAHs) has been reported in several industries, including those of the aluminum production, coal gasification, coke production, iron and steel foundries, coal tar and related products, carbon black and carbon electrodes production.

PATIENTS AND METHODS

This paper reviews the results from cohort studies conducted on workers exposed to PAHs in these industries, with a focus on cancers of the respiratory and urinary tract.

RESULTS

An excess risk from lung/respiratory cancers was found in most industries, the pooled relative risk (RR) being 2.58 (95% CI 2.28-2.92) for coal gasification, 1.58 (95% CI 1.47-1.69) for coke production, 1.40 (95% CI 1.31-1.49) for iron and steel foundries, 1.51 (95% CI 1.28-1.78) for roofers and 1.30 (95% CI 1.06-1.59) for carbon black production. The evidence for cancers of the bladder and of the urinary system is less consistent, with a significant increased risk only for workers in aluminum production (pooled RR = 1.29, 95% CI 1.12-1.49), coal gasification (pooled RR = 2.39, 95% CI 1.36-4.21), and iron and steel foundries (pooled RR = 1.29, 95% CI 1.06-1.57).

CONCLUSIONS

Increased risks from lung and bladder cancers were found in PAH-related occupations. These were modest in most industries, apart from those for coal gasification, and whether they are due at least partially to some bias or confounding remains open to discussion.

Occupational exposure to carbon/coke fibers in plants that produce green or calcined petroleum coke and potential health effects: 2. Fiber concentrations

We monitored exposure to various fibers among workers in eight plants operated by ConocoPhillips that produce green or calcined petroleum coke. Carbon/coke and other fibers, including calcium silicate, cellulose, gypsum, and iron silicate, were found in occupational samples. Carbon/coke fibers were found in bulk samples of calcined petroleum coke, the probable source of these fibers in occupational samples. Time-weighted average (TWA) total fiber concentrations were approximately lognormally distributed; 90% were < or = 0.1 f/ml. Although consistently low, TWA total fiber concentrations varied with plant, job (tasks), and type of coke. This was expected given the substantial differences in plant configuration, technology, and workplace practices among refineries and carbon plants. Carbon/coke fibers (identified and measured using transmission electron microscopy [TEM]) were found at all plants producing all types of calcined coke and not detected at any plant producing only green coke. Approximately 98% of all carbon/coke TWAs were < or = 0.1 f/ml. Analysis of task length average (TLA) data by various statistical techniques indicates that the average carbon/coke TLA is certainly < or = 0.05 f/ml and probably < 0.03 f/ml.

Occupational exposure to carbon/coke fibers in plants that produce green or calcined petroleum coke and potential health effects: 1. Fiber characteristics

Carbon/coke fibers are found in bulk samples of calcined petroleum coke. Carbon/coke and other fibers, including calcium silicate, cellulose, gypsum, and iron silicate, have been found in exposure monitoring of workers who make or handle green or calcined petroleum coke. Carbon/coke fibers are not classified or regulated as carcinogens by any agency, and the available literature (summarized in this article) has not reported significant adverse health effects associated with exposure to these fibers or dusts containing these fibers. However, available epidemiological and toxicological studies have limitations that prevent a definitive assessment of carbon/coke fiber toxicity. Therefore, it is prudent to monitor and control workplace concentrations. Analyses by transmission electron microscopy (TEM) indicate that the carbon/coke fibers are amorphous, irregularly shaped, and generally rather short (94% less than 20 microm long). Nearly all carbon/ coke fibers satisfying NIOSH 7400 B counting criteria are detectable by phase-contrast optical microscopy (PCOM), which permits the use of a highly efficient sequential sampling strategy for analysis. Data are presented on the distribution of carbon/coke structure and fiber lengths and diameters. Bootstrap resampling results are presented to determine confidence intervals for structure/fiber length and diameter. Data on time-weighted average concentrations are given in a companion article, but nearly all time-weighted average carbon/coke fiber concentrations were beneath 0.1 fibers per milliliter.

Determination of dihydroxynaphthalenes in human urine by gas chromatography-mass spectrometry

A gas chromatography-mass spectrometry (GC-MS) method was developed for measuring 1,2-dihydroxynaphthalene (1,2-DHN) and 1,4-dihydroxynaphthalene (1,4-DHN) in urine. The method involves enzymatic digestion of urinary conjugates to release the DHNs which were then analyzed as trimethylsilyl derivatives by GC-MS. For 1,2-DHN and 1,4-DHN, respectively, the assay limits of detection were 0.21 and 0.15 microg/l, the assay limits of quantitation were 0.69 and 0.44 microg/l, and the coefficients of variation were 14.7 and 10.9%. This method was successfully applied to determine urinary levels of 1,2-DHN and 1,4-DHN in coke workers (14 top workers and 13 side-bottom workers) and 21 matching control workers from the steel industry of northern China. The geometric mean (GM) levels of 1,2-DHN were approximately 100 and 30 times higher than those of 1,4-DHN in exposed and control subjects, respectively. The GM levels 1,2-DHN and 1,4-DHN were significantly higher for coke workers (1,2-DHN: top workers--552 microg/l, side-bottom workers--260 microg/l; 1,4-DHN: top workers--3.42 microg/l, side-bottom workers--3.56 microg/l) than for controls (1,2-DHN: 38.8 microg/l; 1,4-DHN: 1.21 microg/l) (p<or=0.0031). In each exposure category, levels of the DHNs were marginally greater in smokers than in nonsmokers (p=0.0646). Strong correlations were observed among 1,2-DHN and 1,4-DHN and previously measured urinary levels of naphthalene, 1-hydroxynaphthalene, and 2-hydroxynaphthalene in these subjects (rs>or=0.623; p<0.0001). Also, levels of 1,2-DHN were significantly correlated with those of serum albumin adducts of l,2-naphthoquinone (rs=0.492, p=0.0004). These results indicate that 1,2- and 1,4-DHN are good biomarkers for assessment of naphthalene exposure in coke workers. Since the DHNs are precursors of the naphthoquinones, which have been implicated as toxic products of naphthalene metabolism, measurements of urinary DHNs may have toxicological significance.

Effects of occupational polycyclic aromatic hydrocarbon exposure on T-lymphocyte functions and natural killer cell activity in asphalt and coke oven workers

Polycyclic aromatic hydrocarbons (PAHs) are environmental carcinogens exhibiting potent immunosuppressive properties. In order to determine PAH-induced immunotoxicity in humans, we investigated possible immunomodulating effects on T-lymphocyte proliferative responses and natural killer (NK) cell activities, at two different exposure levels, in asphalt and coke oven workers. We evaluated the efficiency of urinary 1-hy droxypyrene as a measure of exposure to PAHs. We found a statistically significant inhibition in T-lymphocyte proliferative responses of asphalt and coke oven workers compared to the controls. On the other hand, interestingly, we found significantly higher NK cell activities at three effector:target (E:T) ratios in the asphalt group compared to coke oven and control groups. We conclude that PAHs may cause suppression of T-lymphocyte proliferation at both exposure levels and augment NK cell activity only at low levels of exposure. Our results are in line with others reported in the literature indicating that chronic exposure to PAHs at different levels may alter some immune responses in different ways.

Reduced nucleotide excision repair and GSTM1-null genotypes influence anti-B[a]PDE-DNA adduct levels in mononuclear white blood cells of highly PAH-exposed coke oven workers

It is important to identify the potential genetic-susceptible factors that are able to modulate individual responses to exposure to carcinogenic polycyclic aromatic hydrocarbons (PAHs). In the present study we evaluated the influence of four polymorphisms of nucleotide excision repair (NER) genes [xeroderma pigmentosum-C (XPC)-PAT +/-, xeroderma pigmentosum-A (XPA) 5' non-coding region-A23G, XPD-exon 23 A35931C Lys751Gln, xeroderma pigmentosum-D (XPD)-exon 10 G23591A Asp312Asn] and that of glutathione S-transferase mu1 (GSTM1-active or -null) on benzo[a]pyrene diol epoxide (B[a]PDE)-DNA adduct levels from the lympho-monocyte fraction (LMF) of highly PAH benzo[a]pyrene (B[a]P)-exposed Polish coke oven workers (n = 67, 67% current smokers) with individual urinary post-shift excretion of 1-pyrenol exceeding the proposed biological exposure index (BEI) (2.28 micromol/mol creatinine). The bulky (+/-)-r-7,t-8-dihydroxy-t-9,10-oxy-7,8,9,10-tetrahydrobenzo[a]pyrene (anti-B[a]PDE)-DNA adduct levels were detected by high-performance liquid chromatography (HPLC)/fluorescence analysis and genotypes by polymerase chain reaction. We found that workers with the low DNA repair capacity of XPC-PAT+/+ and XPA-A23A genotypes had significantly increased anti-B[a]PDE-DNA adduct levels (Mann-Whitney U-test, z = 2.24, P = 0.02 and z = 2.65, P = 0.01). Moreover, DNA adducts were also raised in workers without GSTM1 activity (GSTM1-null genotype) (Mann-Whitney U-test, z = 2.25, P = 0.0246). Workers with unfavourable XPC-PAT+/+ and XPA-A23A NER genotypes, alone (approximately 65% of workers) or combined with GSTM1-null genotype (approximately 75% of workers) were in the tertile with the highest adduct level, i.e. >4.11 adducts/10(8) nt (chi2 = 5.85, P = 0.0156 and chi2 = 5.40, P = 0.01). The increase in anti-B[a]PDE-DNA adduct levels (ln values) was significantly related in a multiple linear regression analysis to PAH exposure (i.e. urinary post-shift excretion of 1-pyrenol) (t = 2.61, P = 0.0115), lack of GSTM1 activity (t = 2.41, P = 0.0192) and to low DNA repair capacity of the XPC-PAT+/+ genotype (t = 2.34, P = 0.0226). The influence of the XPA-A23A genotype was not evident in this statistical analysis, and no associations with XPD polymorphisms, dietary habits or tobacco smoking were found. The modulation of anti-B[a]PDE-DNA adducts in the LMF by GSTM1-null and some low-activity NER genotypes may be considered as a potential genetic susceptibility factor capable of modulating individual responses to PAH (B[a]P) genotoxic exposure and the consequent risk of cancer in coke oven workers.

[Effect of genetic polymorphisms of microsomal epoxide hydrolase on urinary 1-hydroxypyrene levels in coke oven workers]

OBJECTIVE

To investigate the associations of polymorphisms of metabolic enzyme genes with urinary 1-hydroxypyrene levels in coke oven workers.

METHODS

One hundred and forty-eight workers from a coke oven plant and 69 controls without occupational PAHs exposure were selected in this study. Urinary 1-hydroxypyrene was detected by high performance liquid chromatography with florescence detector. The genotypes at I462V site in exon 7 of CYP1A1 gene, GSTM1, GSTT1, I105V site in GSTP1gene, Pst1 and Dra1 sites in CYP2E1 gene, P187S site in NQO1 gene, Kpn1, BamH1 and Taq1 sites in NAT2 gene, and H113Y, R139H sites in mEH gene were determined by PCR-based methods. Personal information including occupational exposure history, age, sex, smoking and drinking status was collected by the questionnaire.

RESULTS

The level of urinary 1-hydroxypyrene in coke oven workers [(5.61 +/- 1.04) mol/mol Cr] was higher than that in control [(0.74 +/- 0.32) micro mol/mol Cr]. After adjusting external occupational exposure category and smoking, coke oven workers with variant homozygotes at H113Y site of mEH gene had significantly higher urinary 1-hydroxypyrene concentrations than those with heterozygotes, and wild homozygotes (6.41 +/- 1.09 vs. 6.24 +/- 1.08, and 4.62 +/- 0.95 micro mol/mol Cr, P < 0.05), and gene-gene interaction was found between CYP1A1 and mEH.

CONCLUSION

Genetic polymorphism of mEH gene could be a susceptible biomarker in coke oven workers which was involved in the individual susceptibility on metabolism of PAHs.

[Relationship of polycyclic aromatic hydrocarbon exposure with peripheral blood lymphocyte DNA damage in coke oven workers]

OBJECTIVE

To investigate the relationship between lymphocyte DNA damage and polycyclic aromatic hydrocarbons (PAHs) exposure in coke oven workers.

METHODS

Two hundred and thirty-five coke oven workers and 30 controls were selected in this study. Alkaline single-cell gel electrophoresis was used to evaluate the lymphocyte DNA damage, HPLC was employed to measure 1-hydroxypyrene levels in spot urine samples which were obtained at the end of a workweek (4 days of 8 hours/day) and personal information including occupational exposure, age, sex, smoking and drinking status was collected by the questionnaire.

RESULTS

The lymphocyte DNA damage level expressed as olive moment in coke oven workers was significantly higher than that of controls [2.47 (0.22 approximately 46.68) vs 0.94 (0.42 approximately 4.21), P < 0.01], and correlation between urinary 1-hydroxypyrene concentrations and olive moment was found (Spearman Partial correlation coefficient = 0.22, P < 0.01) in coke oven workers. The 1.9 of olive moment value was used as the limit to determine whether the subject DNA damage was positive. The coke oven workers had significantly higher risk in DNA damage (adjusted OR = 5.38, 95% CI = 2.07 approximately 14.08) than did controls, and dose-response relationships were also found between external exposure (exposure category) or internal doses (urinary 1-hydroxypyrene) and DNA damage.

CONCLUSION

There are dose-effect and dose-response relationships between PAHs exposure and lymphocyte DNA damage in 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.

[A study on the relationship between urinary 1-hydroxypyrene level and early genetic effect among coke oven workers]

OBJECTIVE

To investigate the relationship between the urinary 1-hydroxypyrene level and cytokinesis-block micronucleus and the olive moment of comet assay in peripheral blood lymphocyte in coke oven workers.

METHODS

One hundred and thirty-three workers from a coke plant and 28 referents without occupational PAH exposure were recruited in this study. Urinary level of 1-hydroxypyrene was measured by alkaline hydrolysis combined with high performance liquid chromatography as an internal exposure dose, and the DNA and chromosomal damage of peripheral blood lymphocyte were evaluated with comet assay and cytokinesis-block micronucleus method. Personal information including occupational history, age, sex, smoking and alcohol drinking, was collected by questionnaire.

RESULTS

There existed a good correlationship between the urinary level of 1-hydroxypyrene and frequency of micronuclei per 1 000 binucleated cells or the olive moment of comet assay in the study subjects, after adjusting for sex, age, smoking and alcohol drinking (r > 0.25, P < 0.01). One hundred and sixty-one subjects were divided into three groups by their urine 1-hydroxypyrene level (expressed as 0.30 - 2.44, 2.45 - 7.09 and 7.10 - 33.10 micro mol/mol Cr), and the geometric means of their urinary levels of 1-hydroxypyrene were 1.14, 4.32 and 12.49 micro mol/mol Cr, respectively. After adjusting for age, sex, smoking and alcohol drinking by multiple nonparametric analysis of covariance, the median of olive moment of comet assay in the group of 7.10 - 33.10 micro mol/mol Cr was 3.67, significantly higher than that in the groups of 0.30 - 2.44 and 2.45 - 7.09; and the micronuclei frequencies in the groups of 2.45 - 7.09 and 7.10 - 33.10 micro mol/mol Cr were 8.00 per thousand and 7.50 per thousand, respectively, significantly higher than that in the group of 0.30 - 2.44 micro mol/mol Cr (6.00 per thousand ).

CONCLUSIONS

The comet assay of peripheral blood lymphocyte was more suitable to detect the PAHs-induced early genotoxicity, than the cytokinesis-block micronucleus.

Urinary excretion of 8-hydroxy-2-deoxyguanosine and 1-hydroxypyrene in coke-oven workers

Coke-oven workers (COWs) are occupationally exposed to high concentrations of polycyclic aromatic hydrocarbons (PAH). Urinary 8-hydroxy-2-deoxyguanosine (8-OH-dG) and 1-hydroxypyrene (1-OHP) are biological markers of oxidative DNA damage and PAH metabolism, respectively. We investigated the relationship between urinary 8-OH-dG and 1-OHP in 217 Taiwanese COWs, 55 topside-oven, and 162 sideoven workers. For topside-oven workers, mean 8-OH-dG and 1-OHP concentrations (ng/ml +/- SD) were 13.8 +/- 12.0 and 93.5 +/- 104.4, respectively. These levels were significantly higher than those for sideoven workers: 10.2 +/- 7.9 ng/ml (P = 0.04) and 19.8 +/- 28.6 ng/ml (P < 0.001), respectively. Individual urinary 8-OH-dG concentrations were directly correlated with urinary 1-OHP concentrations: the higher the 1-OHP level, the higher the 8-OH-dG level (Spearman correlation coefficients: r = 0.43, P < 0.0001, n = 217). Multiple regression analysis indicated that a 10-fold increase in 1-OHP was associated with a 1.91-fold increase in 8-OH-dG. Compared to no vitamin intake, intake of at least one multiple vitamin pill per week reduced 8-OH-dG excretion (P = 0.02). Our findings suggest that urinary 1-OHP and 8-OH-dG reflect occupational PAH exposure and oxidative DNA damage in COWs. In addition, multiple vitamins may reduce oxidative stress caused by PAH exposure.

Cytochrome P450 1B1 mRNA levels in peripheral blood cells and exposure to polycyclic aromatic hydrocarbons in Chinese coke oven workers

Cytochrome P450 1B1 (CYP1B1) is induced through the Ah receptor and is involved in the activation of polycyclic aromatic hydrocarbons (PAHs). To determine the validity of a quantitative analysis of CYP1B1 mRNA in peripheral human blood cells for the estimation of PAH exposure, a real-time quantitative polymerase chain reaction method was used to measure the relative levels of CYP1B1 mRNA in 37 Chinese coke oven workers and 13 control workers. A large inter-individual difference in the levels was observed. The average level of the CYP1B1 mRNA in workers at the top work site, where the PAH exposure level from the coke ovens was highest, was significantly higher than in workers at the middle site (P<0.01) or the controls (P=0.02). A non-significant positive correlation was found between the CYP1B1 mRNA levels and urinary 1-hydroxypyrene (R=0.22, P=0.13), and a significant correlation between these mRNA levels and urinary cotinine (R=0.33, P=0.02). It was interesting that a significant positive correlation between CYP1B1 mRNA and 1-hydroxypyrene was observed in subjects with the Leu/Leu type of CYP1B1 Leu432Val polymorphism (R=0.33, P=0.02, n=38) and a non-significant correlation in subjects with the Leu/Val and Val/Val types (R=-0.36, P=0.25, n=12), although the number of subjects in this strata analysis was small. Our preliminary study suggests that PAH exposure in coke ovens and smoking maybe associated with CYP1B1 mRNA levels in peripheral blood cells although mRNA is generally unstable and could be expressed following exposure to other agents.

Urinary 1-hydroxypyrene in coke oven workers relative to exposure, alcohol consumption, and metabolic enzymes

OBJECTIVES

To investigate the influence of personal lifestyle--such as smoking and alcohol consumption-on urinary 1-hydroxypyrene (1-OHP) concentrations in coke oven workers exposed to polycyclic aromatic hydrocarbons (PAHs) and to evaluate the association of 1-OHP concentrations with the genetic polymorphism of several metabolic enzymes including cytochrome P-450 (CYP) 1A1 and glutathione S-tranferases (GSTs).

METHODS

The study population contained 162 coke oven workers and 58 controls employed at the largest iron and steel factory in China. Personal data were collected at the interview. 1-OHP in urine was measured with high performance liquid chromatography with fluorescence detection. Genetic polymorphisms were identified by the polymerase chain reaction (PCR) method.

RESULTS

A positive association between excretion of urinary 1-OHP and the levels of exposure to PAHs was confirmed. Those people who consumed >or=50 g/day ethanol had significantly higher 1-OHP excretion than did other coke oven workers (p<0.01). No significant difference in urinary 1-OHP was found between smokers and non-smokers, in both controls and exposed subjects. The variant homozygotes at exon 7 of the CYP1A1 gene had significantly higher urinary 1-OHP concentrations than other CYP1A1 genotypes among the exposed workers (p=0.03). There was less association between the concentrations of 1-OHP and the GSTM1, GSTP1, or GSTT1 polymorphism.

CONCLUSIONS

The present study confirmed that urinary 1-OHP is a good biomarker for exposure to PAHs. Alcohol consumption affected urinary 1-OHP excretion. The variant genotypes of the CYP1A1 gene may result in the enhancement of PAH metabolites. It is helpful to understand the role of individual susceptibility on metabolism of carcinogens. These findings suggest that the modulating effect of individual lifestyle factors or genetic nature should be considered in future studies on occupational exposure to PAHs and in evaluating the health risk from harmful chemicals.

Proximity to coke works and hospital admissions for respiratory and cardiovascular disease in England and Wales

BACKGROUND

The incidence of hospital admissions for respiratory and cardiovascular diseases in areas close to operating coke works in England and Wales was investigated.

METHODS

A small area study using distance from source as a proxy for exposure was undertaken in subjects aged 65 or over and children under 5 years within 7.5 km of four coke works (1991 estimated populations 87 760 and 43 932, respectively). The main outcome measures were emergency hospital admissions in 1992/3-1994/5 with a primary diagnosis of coronary heart disease (ICD 410-414), stroke (ICD 431-438), all respiratory diseases (ICD 460-519), chronic obstructive pulmonary disease (ICD 491-492), and asthma (ICD 493) in those aged 65 or over, and all respiratory and asthma admissions in children under 5 years of age.

RESULTS

At age 65 or over the combined estimate of relative risk with proximity to coke works (per km) ranged from 0.99 (95% CI 0.90 to 1.09) for chronic obstructive pulmonary disease to 1.03 (95% CI 0.94 to 1.13) for asthma. For children under 5 years the combined estimate of risk was 1.08 (95% CI 0.98 to 1.20) for all respiratory disease and 1.07 (95% CI 0.98 to 1.18) for asthma. There was evidence of significant heterogeneity in risk estimates between coke work groups, especially in children under 5 years (p<0.001 and p=0.004 for respiratory disease and asthma, respectively). For the Teesside coke works in North East England the relative risk with proximity (per km) was 1.09 (95% CI 1.06 to 1.12) for respiratory disease and 1.09 (95% CI 1.04 to 1.15) for asthma.

CONCLUSIONS

No evidence overall was found for an association between hospital admissions and living near operational coke works in England and Wales. Trends of a higher risk of hospital admission for respiratory disease and asthma among children with proximity to the Teesside plant require further investigation.

Aromatic DNA adducts in coke-oven workers, in relation to exposure, lifestyle and genetic polymorphism of metabolic enzymes

OBJECTIVE

This study investigates the effect of multiple factors, including exposure to polycyclic aromatic hydrocarbons (PAHs), lifestyle, genetic polymorphism of cytochrome P450 (CYP)1A1, glutathione transferase (GST)M1, GSTP1, N-acetyltransferase (NAT)2 and gene p53, as well as any family history of cancer, on DNA adduct levels in coke-oven workers.

METHODS

Sixty-five coke-oven workers employed at the largest iron-steel factory in China were recruited for the study. Personal data were collected at the interview. DNA adduct levels in total white blood cells (WBCs) were detected using 32P-postlabeling techniques. Genetic polymorphisms were analyzed by polymerase chain reaction (PCR) methods.

RESULTS

The subjects were divided into low and high exposure groups, according to personal exposure to PAHs. The mean adduct value was 1.57 (range 0.54 to 4.35) per 10(8) nucleotides. A tendency for increased levels of DNA adducts in the high exposure group was observed, compared with the low exposure group (P = 0.07). In the low exposure group, DNA adducts were found to be positively associated with urinary cotinine (r = 0.44, P = 0.01). The rare allele homozygotes of CYP1A1 showed significantly higher DNA adduct levels than those of other CYP1A1 genotypes. Individuals with the NAT2 wild type had significantly increased DNA adduct levels than those with other NAT2 genotypes in the high exposure group. The p53 genetic polymorphism revealed a significantly positive effect on DNA adducts formation. There was a significantly higher adduct level in the subjects with a family history of cancer than those without, in the high exposure category.

CONCLUSIONS

Effects of several variables, such as smoking, genetic polymorphism of 2 CYP1A1, NAT2, and gene p53, and a family history of cancer on DNA adduct levels were found, suggesting that these variables should be considered when evaluating the genotoxic effect of occupational exposure to PAHs using WBCs DNA adducts.

Chromosome damage and aneuploidy detected by interphase multicolour FISH in benzene-exposed shale oil workers

A multicolour tandem-labelling fluorescence in situ hybridization (FISH) procedure was used to detect chromosome alterations in peripheral blood cells of a group of Estonian petrochemistry workers. Twelve workers employed in benzene production and five cokery workers, together with eight unexposed rural controls, were enrolled in the study. The methodology employed, based on the in situ hybridization of adjacent centromeric and pericentromeric regions, allowed the simultaneous detection of both chromosome breakage, involving damage-prone pericentromeric regions, and hyperploidy in interphase cells. Blood smears from all subjects were hybridized with chromosome 1 specific probes, in order to detect genotoxic damage in circulating lymphocytes and granulocytes. Moreover, lymphocyte cultures were established, harvested 48 h following mitogen stimulation and hybridized with the tandem chromosomes 1 and 9 probes. No significant difference in the incidence of breakage was detected in the nucleated cells of blood smears of exposed vs. control subjects. In contrast, modest but significantly increased frequencies of breakage affecting both chromosomes 1 and 9 were observed in the cultured lymphocytes of the benzene-exposed workers compared to the unexposed controls, suggesting an expression of premutagenic lesions during the S-phase in vitro. Across the entire study group, the frequencies of breakage affecting chromosomes 1 and 9 in the stimulated lymphocytes were highly intercorrelated (p < 0.001). No significant difference was found in the incidence of hyperploidy among the study groups, although a tendency to higher values was observed in benzene-exposed workers. Although the relatively small size of the study groups does not allow firm conclusions on the role of occupational exposure, the observed patterns are suggestive of effects in the benzene-exposed workers. This work also shows that tandem labelling FISH can be usefully applied in human biomonitoring, allowing the simultaneous detection of both hyperploidy and chromosome breakage at interphase in different cell types.

Estimation of unit risk for coke oven emissions

In 1984, based on epidemiological data on cohorts of coke oven workers, USEPA estimated a unit risk for lung cancer associated with continuous exposure from birth to 1 microgram/m3 of coke oven emissions, of 6.2 x 10(-4). This risk assessment was based on information on the cohorts available through 1966. Follow-up of these cohorts has now been extended to 1982 and, moreover, individual job histories, which were not available in 1984, have been constructed. In this study, lung cancer mortality in these cohorts of coke oven workers with extended follow-up was analyzed using standard techniques of survival analysis and a new approach based on the two stage clonal expansion model of carcinogenesis. The latter approach allows the explicit consideration of detailed patterns of exposure of each individual in the cohort. The analyses used the extended follow-up data through 1982 and the detailed job histories now available. Based on these analyses, the best estimate of unit risk is 1.5 x 10(-4) with 95% confidence interval = 1.2 x 10(-4)-1.8 x 10(-4).

Estimation of unit risk for coke oven emissions

In 1984, based on epidemiological data on cohorts of coke oven workers, USEPA estimated a unit risk for lung cancer associated with continuous exposure from birth to 1 microgram/m3 of coke oven emissions, of 6.2 x 10(-4). This risk assessment was based on information on the cohorts available through 1966. Follow-up of these cohorts has now been extended to 1982 and, moreover, individual job histories, which were not available in 1984, have been constructed. In this study, lung cancer mortality in these cohorts of coke oven workers with extended follow-up was analyzed using standard techniques of survival analysis and a new approach based on the two stage clonal expansion model of carcinogenesis. The latter approach allows the explicit consideration of detailed patterns of exposure of each individual in the cohort. The analyses used the extended follow-up data through 1982 and the detailed job histories now available. Based on these analyses, the best estimate of unit risk is 1.5 x 10(-4) with 95% confidence interval = 1.2 x 10(-4)-1.8 x 10(-4).

Cytochrome P450 1A1 MspI polymorphism and urinary 1-hydroxypyrene concentrations in coke-oven workers

Coke-oven workers are regularly exposed to a high concentration of the benzene-soluble fraction (BSF) of total particulates, which are comprised mainly of polycyclic aromatic hydrocarbons (PAHs). A metabolite of pyrene, 1-hydroxpyrene (1-OHP), is readily measured in the urine of exposed individuals. Epidemiological studies have shown that P4501A1 (CYP1A1) genotypes are associated with PAH-related lung cancer risk. The purpose of this study was to investigate whether CYP1A1 MspI genotypes modulate the relationship of individual occupational exposure to air BSF to urinary 1-OHP concentrations among coke-oven workers. We monitored individual breathing zone air BSF over 3 consecutive days in 80 coke-oven workers in Taiwan from August 1995 to February 1996. Exposure was also dichotomized by work area (topside oven workers and sideoven workers). Preshift urine on the morning of day 1 and postshift urine on the afternoon of day 3 were measured by fluorescent spectrophotometry, and blood samples were analyzed to determine the relative distributions of CYP1A1 MspI polymorphisms. The frequency of the MspI homozygous variant genotypes of CYP1A1 was 15%. Multiple linear regression showed significant effects of individual occupational exposure to air BSF and preshift 1-OHP on postshift urinary 1-OHP concentrations (P = 0.002 and P < 0.001, respectively). After adjusting for preshift 1-OHP concentrations and air BSF, subjects with the homozygous variant genotype have a 2-fold higher postshift 1-OHP levels than the combined wild-type and heterozygous (P = 0.04). In addition, a positive trend was found in postshift 1-OHP and across-shift change of 1-OHP (postshift 1-OHP - preshift 1-OHP) in decreasing order, as follows: topside oven workers with the homozygous variant trait, topside oven workers with the heterozygous variant trait, sideoven workers with the homozygous variant trait, and sideoven workers with the heterozygous trait (P < 0.001). We conclude that CYP1A1 MspI variant genotype can modify the metabolism of PAHs in coke-oven workers.

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.

[Detection of sister chromatic exchange in workers exposed to coal tar pitch and to coke oven volatiles]

In order to know the changes of genetic toxicological effects on workers occupationally exposed to polycyclic aromatic hydrocarbons (PAHs), sister chromatic exchange(SCE) was detected by the methods of peripheral lymphocyte culture in 23 workers exposed to coal tar pitch (CTP) and in 19 workers exposed to coke oven volatiles (COV) and 12 normal controls. The results suggested that the SCE in occupational workers was significantly higher than that in controls (11.31 vs 6.37, P < 0.001). The SCE in workers exposed to CTP and to COV was higher than that of control (10.27 and 12.58 vs 6.37) respectively. In workers exposed to CTP and COV, there were no differences of SCE for smokers and nonsmokers (P > 0.05). It is indicated that CTP and COV caused strong genetic toxicity and injury to chromosome.

Genotoxicity of coke-oven and urban air particulate matter in in vitro acellular assays coupled with 32P-postlabeling and HPLC analysis of DNA adducts

This study is an in vitro part of the ongoing biomarker studies with population from a polluted region of Northern Bohemia and coke-oven workers from Czech and Slovak Republics. The aim of this study is to compare DNA adduct forming ability of chemical compound classes from both the urban and coke-oven extractable organic mass (EOM) of airborne particles. The crude extracts were fractionated into seven fractions by acid-base partitioning and silica gel column chromatography. In in vitro acellular assays we used calf thymus DNA (CT DNA) with oxidative (+S9) and reductive activation mediated by xanthine oxidase (+XO) under anaerobic conditions. Both the butanol and nuclease P1 versions of 32P-postlabeling for detection of bulky aromatic and/or hydrophobic adducts were used. The results showed that the spectra of major DNA adducts resulting from both the in vitro assays are within the fractions similar for both the urban and coke-oven samples. The highest DNA adduct levels with S9-activation were detected for the neutral aromatic fraction, followed by slightly polar and acidic fractions for both samples. With XO-mediated metabolism, the highest DNA adduct levels were detected for both the acidic fractions. Assuming additivity of compound activities, then the acidic fraction, which in the urban sample comprises a major portion of EOM mass (28%), may contain the greatest activity in both in vitro assays (39 and 69%, +S9 and +XO, respectively). In contrast, the aromatic fraction constituting only 8% of total urban EOM mass may account for comparable activity (34%) with organic acids. The highest DNA adduct forming activity of the coke-oven sample accounts for the aromatic fraction (82 and 63%, +S9 and +XO, respectively) that also contains the greatest portion of the total EOM (48%). To characterize some of the specific DNA adducts formed, we coupled TLC on 20x20 cm plates with HPLC analysis of 32P-postlabeled adducts. In both S9-treated samples of the aromatic fraction, we tentatively identified DNA adducts presumably diolepoxide-derived from: 9-hydroxy-benzo[a]pyrene (9-OH-B[a]P), benzo[a]pyrene-r-7,t-8-dihydrodiol-t-9,10-epoxide[+/-] (anti-BPDE), benzo[b,j,k]fluoranthenes (B[b]F, B[j]F, B[k]F), chrysene (CHRY), benz[a]-anthracene (B[a]A) and indeno[cd]pyrene (I[cd]P). These DNA adducts accounted for about 57% of total DNA adducts detected in both S9-treated samples of the aromatic fraction. DNA adducts of XO-treated samples were sensitive to nuclease P1 and HPLC profiles of the major adducts were markedly different from the major adducts of S9-treated samples. However, the combination of TLC and HPLC did not confirm the presence of DNA adducts derived from 1-nitropyrene (1 NP), 9-nitroanthracene (9 NA) and 3-nitrofluoranthene (3 NF) that were detected by GC-MS in the slightly polar fraction. We concluded that the chemical fractionation procedure facilitates the assessing of DNA adduct forming ability of different chemical compound classes. However, based on the results obtained with the whole extracts, it does not fulfil a task of the actual contribution of individual fractions within the activity of the whole extracts. Our results are the first in detecting of DNA adducts derived from urban air and coke-oven particulate matter.

Urinary excretion of phenols as an indicator of occupational exposure in the coke-plant industry

OBJECTIVE

In the present study the relationship between the level of exposure to o-cresol and of 2,4- +2,5-, 3,4-, and 3,5-xylenols and the urinary excretion of their metabolites was examined. The mixed exposure to phenolic derivatives of exposed workers during their work shift was monitored by personal air sampling of the breathing-zone air and by measurements of phenol, o-cresol, and xylenol isomer concentrations in shift-end urine.

METHODS

The study subjects were 76 men working at a coke plant who were 22-58 years old and 34 nonexposed subjects. Concentrations of phenolic compounds were determined in the breathing-zone air during the work shift, whereas concentrations of phenol, cresol, and xylenol isomers were measured in urine collected after the work shift. Concentrations of phenols in air and urine were determined by gas chromatography with flame-ionization detection. Urine samples were extracted after acid hydrolysis of glucuronides and sulfates by solid-phase extraction. The gas chromatography-mass spectrometry method was applied to identify metabolites in urine samples.

RESULTS

The time-weighted average concentrations of phenol, cresol, and xylenol isomers detected in breathing-zone air showed that the exposure level of the workers was relatively low. The geometric mean values were as follows: 0.26 mg/m3 for phenol, 0.09 mg/m3 for o-cresol, 0.13 mg/m3 for p- and m-cresol, and 0.02-0.04 mg/m3 for xylenols at the tar-distillation process. Corresponding urinary concentrations were 10.39, 0.53, and 0.25-0.88 mg/g creatinine for phenol, o-cresol, and xylenol isomers, respectively. The correlation coefficients between the o-cresol and 2,4-, 2,5-, 3,4-, and 3,5-xylenol concentrations measured in urine and in the breathing-zone air were statistically significant, varying in the range of 0.54-0.74 for xylenol isomers and being 0.69 for o-cresol.

CONCLUSION

We have found that the presence of o-cresol and xylenol isomers in urine can be used as a biomarker for phenol exposure. Analysis performed on workers at the tar-distillation process showed that they were exposed to relatively low concentrations of phenolic compounds.

Serum liver function profiles in coking workers

Coking workers are regularly exposed to coke oven emissions (COE), which consist mainly of polycyclic aromatic hydrocarbons and volatile organic compounds. In a previous cross-sectional study, we found that coking and by-product workers with heavy exposure to COE in the older of two coke operation areas in Taiwan had higher serum activities of hepatic aminotransferase than the controls. In this study, we further examine the relationship of exposure to COE with liver function profiles in coking workers. Liver function profiles included serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyl transpeptidase (GGT), alkaline phosphatase (ALP), and total bilirubin (BIL). The exposed group included 88 workers working 3 months or more in the older coke oven plant. Fifty-nine referents, not visiting the coke operation areas in the last 3 months, came from the administrative area in the same company. Each participant wore a personal monitor that was used to measure benzene soluble fraction (BSF) of total particulates, as a surrogate of COE, for 3 consecutive days between August 1995 and February 1996. Serum liver function profiles, hepatitis B surface antigens, and anti-hepatitis C antibodies were examined in the morning following the exposure measurements. Exposure levels were categorized by exposure situations (high, medium, low) among coking workers. The high exposure group (n = 23) worked topside of the oven. The medium exposure group (n = 44) worked at the sideoven for more than 4 hr/day, whereas the low exposure group (n = 21) worked at the sideoven for less than 4 hr/day and mostly remained in the control rooms. The low exposure group was used as an internal comparison group. The median BSF concentrations for various exposure situations were as follows, high exposure group: 372 micrograms/m3, medium exposure group: 61 micrograms/m3, low exposure group: 49 micrograms/m3, and referents: 10 micrograms/m3. The coking workers (n = 88) did not significantly differ from the referents (n = 59) in any of the liver function profiles. Excluding the referents, workers in the high exposure group had a mean AST level that was 31% higher (95% confidence interval (CI) = 9-57%) and a mean ALT level that was 46% higher (95% CI = 7-98%) than those in the low exposure group after adjusting for appropriate confounders in multivariate models. The prevalence of an abnormal hepatocellular pattern (AST > 37 IU/L or ALT > 39 IU/L) was more common in the high exposure group than in the low exposure group (adjusted odds ratio = 4.4; 95% CI = 0.9-22.6). However, these associations were not found in GGT, ALP, or BIL. After controlling for the possible effects of nonoccupational factors on serum activity of AST and ALT, we conclude that increased AST and ALT levels among topside coking workers may be caused by heavy inhalation exposure to COE. Additionally, the adverse hepatic effect seems to be caused by a mixture of hazards, rather than a unique identifiable chemical.

Elevated serum liver enzymes in coke oven and by-product workers

Coke oven and by-product workers are potentially exposed to coke oven emissions (COE), which contain hundreds of chemicals and are primarily composed of polycyclic aromatic hydrocarbons (PAH) and volatile organic compounds. Some of these compounds are hepatotoxins. The objective of this study was to examine the relationship between work in coke oven and by-product plants and serum activities of aspartate aminotransferase (AST) and alanine aminotransferase (ALT), the most commonly performed liver-function tests. The exposed group was composed of current workers who had been employed at least 3 months in the two coke-operation work areas, including one coke oven plant and one by-product plant (Area I: n = 117; Area II: n = 96) of a large steel company in Taiwan. Control subjects (Area III: n = 131), not visiting either coke-operation area in the last 3 months, were collected from the administrative and nonproduction areas in the same company. PAH exposure, as a surrogate of COE, was measured monthly by PM-10 size-selective high-volume-area air samplers in or around these three areas between June and December 1990, as well as between November 1992 and June 1993. The mean total respiratory particulate PAH exposure levels (< 10 microns) between November 1992 and June 1993 in Area I, II, and III were 6.8 x 10(3), 2.1 x 10(3), and 6.5 x 10(1) ng/m3, respectively. AST, ALT, and hepatitis B surface antigen tests were performed in 1994. Workers who showed either AST or ALT levels greater than reference levels (abnormal > 25 IU/L) were regarded as showing "elevated liver enzyme levels." Workers in Area I had AST levels that were 17% higher (95% confidence interval [CI], 3% to 32%]) and ALT levels that were 35% higher (95% CI, 10% to 65%)] than those in Area III after controlling for appropriate confounders. The adjusted odds ratio (Area I vs Area III) for elevated liver enzymes was 4.4 (95% CI, 1.5 to 13.4). In addition, coke oven (n = 91) and by-product workers (n = 26) from Area I had ALT levels 37% and 45% higher, respectively, compared with control subjects from Area III, after adjusting for appropriate confounders. Similar effects are also seen for AST. Workers in Area II had slightly, but not significantly, elevated AST and ALT levels. These results indicate that workers most heavily exposed to COE exhibit elevated aminotransferase levels.

Can we detect mutagenic activity of urinary sediment by the Ames test?

Using the Salmonella typhimurium strain TA98 we tested the mutagenicity of filtrate and sediment of urine collected from children and coke-oven workers living in the town of Dabrowa Górnicza. Mutagenic substances were detected in samples of urinary filtrate taken either from environmentally exposed children or from occupationally exposed coke-oven workers. The mutagenic effect was found only in acetone extracts of urinary filtrate in the presence of promutagenic activating fraction S9. Beta-glucuronidase/arylsulphatase treatment hydrolysed the conjugates contained urinary filtrate into compounds that were toxic towards tester strain. The mutagenic effect of urine should be tested only in urinary filtrate as we have never detected mutagenic substances in urinary sediment.