Influence of GSTM1 genotype on association between aromatic DNA adducts and urinary PAH metabolites in incineration workers

Predictors of polycyclic aromatic hydrocarbon exposure and internal dose in inner city Baltimore children

Polycyclic aromatic hydrocarbons (PAHs), the by-products of incomplete combustion of organic materials, are commonly found on particulate matter (PM) and have been associated with the development of asthma and asthma exacerbation in urban populations. We examined time spent in the home and outdoors as predictors of exposures to airborne PAHs and measured urinary 1-hydroxypyrene-glucuronide (1-OHPG) as internal dose of PAHs in 118 children aged 5-12 years from Baltimore, MD. During weeklong periods (Saturday-Saturday) in each of four seasons: daily activities were assessed using questionnaires, indoor air nicotine and PM concentrations were monitored, and urine specimens were collected on Tuesday (day 3) and Saturday (day 7) for measurement of 1-OHPG. Time spent in non-smoking homes was associated with significantly decreased 1-OHPG concentration in urine (β=-0.045, 95% CI (-0.076, -0.013)), and secondhand smoke (SHS) exposures modified these associations, with higher urinary 1-OHPG concentrations in children spending time in smoking homes than non-smoking homes (P-value for interaction=0.012). Time spent outdoors was associated with increased urinary 1-OHPG concentrations (β=0.097, 95% CI (0.037, 0.157)) in boys only. Our results suggest that SHS and ambient (outdoor) air pollution contribute to internal dose of PAHs in inner city children.

Polycyclic aromatic hydrocarbons and esophageal squamous cell carcinoma

Esophageal cancer (EC) is the 8th most common cancer and the 6th most frequent cause of cancer mortality worldwide. Esophageal squamous cell carcinoma (ESCC) is the most common type of EC. Exposure to polycyclic aromatic hydrocarbons (PAHs) has been suggested as a risk factor for developing ESCC. In this paper we will review different aspects of the relationship between PAH exposure and ESCC. PAHs are a group of compounds that are formed by incomplete combustion of organic matter. Studies in humans have shown an association between PAH exposure and development of ESCC in many populations. The results of a recent case-control study in a high risk population in northeastern Iran showed a dramatic dose-response relationship between PAH content in non-tumor esophageal tissue (the target tissue for esophageal carcinogenesis) and ESCC case status, consistent with a causal role for PAH exposure in the pathogenesis of ESCC.  Identifying the main sources of exposure to PAHs may be the first and most important step in designing appropriate PAH-reduction interventions for controlling ESCC, especially in high risk areas. Coal smoke and drinking mate have been suggested as important modifiable sources of PAH exposure in China and Brazil, respectively. But the primary source of exposure to PAHs in other high risk areas for ESCC, such as northeastern Iran, has not yet been identified. Thus, environmental studies to determining important sources of PAH exposure should be considered as a high priority in future research projects in these areas.

Burnt sugarcane harvesting: particulate matter exposure and the effects on lung function, oxidative stress, and urinary 1-hydroxypyrene

Non-mechanised sugarcane harvesting preceded by burning exposes workers and the people of neighbouring towns to high concentrations of pollutants. This study was aimed to evaluate the respiratory symptoms, lung function and oxidative stress markers in sugarcane workers and the residents of Mendonça, an agricultural town in Brazil, during the non-harvesting and harvesting periods and to assess the population and individual exposures to fine particulate matter (PM(2.5)). Sugarcane workers and healthy volunteers were evaluated with two respiratory symptom questionnaires, spirometry, urinary 1-hydroxypyrene levels, and the measurement of antioxidant enzymes and plasma malonaldehyde during the non-harvesting and harvesting periods. The environmental assessment was determined from PM(2.5) concentration. PM(2.5) level increased from 8 μg/m³ during the non-harvesting period to 23.5 μg/m³ in the town and 61 μg/m³ on the plantations during the harvesting period. Wheezing, coughing, sneezing, and breathlessness increased significantly in both groups during the harvesting period, but more markedly in workers. A decrease in lung function and antioxidant enzyme activity was observed in both populations during harvesting; this decrease was greater among the sugarcane workers. The urinary 1-hydroxypyrene levels only increased in the sugarcane workers during the harvesting period. The malonaldehyde levels were elevated in both groups, with a higher increase observed in the workers. This research demonstrates the exposure of sugarcane workers and the inhabitants of a neighbouring town to high PM(2.5) concentrations during the sugarcane harvest period. This exposure was higher among the sugarcane workers, as illustrated by both higher PM(2.5) concentrations in the sugarcane fields and higher urinary 1-hydroxypyrene levels in the volunteers in this group. The higher incidence of respiratory symptoms, greater decrease in lung function and more marked elevation of oxidative stress markers among the sugarcane workers during the harvest confirms the greater effect magnitude in this population and a dose-dependent relationship between pollution and the observed effects.

Exposure to Polycyclic Aromatic Hydrocarbons Among Never Smokers in Golestan Province, Iran, an Area of High Incidence of Esophageal Cancer - a Cross-Sectional Study with Repeated Measurement of Urinary 1-OHPG in Two Seasons

Studies have suggested a possible role of polycyclic aromatic hydrocarbons (PAHs) in the etiology of esophageal cancer in Golestan Province, Iran, where incidence of this cancer is very high. In order to investigate the patterns of non-smoking related exposure to PAHs in Golestan, we conducted a cross-sectional study collecting questionnaire data, genotyping polymorphisms related to PAH metabolism, and measuring levels of 1-hydroxypyrene glucuronide (1-OHPG), a PAH metabolite, in urine samples collected in two seasons from the same group of 111 randomly selected never-smoking women. Beta-coefficients for correlations between 1-OHPG as dependent variable and other variables were calculated using linear regression models. The creatinine-adjusted 1-OHPG levels in both winter and summer samples were approximately 110 μmol/molCr (P for seasonal difference = 0.40). In winter, red meat intake (β = 0.208; P = 0.03), processed meat intake (β = 0.218; P = 0.02), and GSTT1-02 polymorphism ("null" genotype: β = 0.228; P = 0.02) showed associations with 1-OHPG levels, while CYP1B1-07 polymorphism (GG versus AA + GA genotypes: β = -0.256; P = 0.008) showed an inverse association. In summer, making bread at home (> weekly versus never: β = 0.203; P = 0.04), second-hand smoke (exposure to ≥3 cigarettes versus no exposure: β = 0.254; P = 0.01), and GSTM1-02 "null" genotype (β = 0.198; P = 0.04) showed associations with 1-OHPG levels, but GSTP1-02 polymorphism (CT + TT versus CC: β = -0.218; P = 0.03) showed an inverse association. This study confirms high exposure of the general population in Golestan to PAHs and suggests that certain foods, cooking methods, and genetic polymorphisms increase exposure to PAHs.

Aromatic DNA adducts and polymorphisms in metabolic genes in healthy adults: findings from the EPIC-Spain cohort

Aromatic compounds such as polycyclic aromatic hydrocarbons, arylamines and heterocyclic amines require metabolic activation to form metabolites able to bind to DNA, a process mediated by polymorphic enzymes. We measured aromatic DNA adducts in white blood cells by the (32)P-post-labelling assay in a sample of 296 healthy adults (147 men and 149 women) from five regions of Spain. We also analyzed functional polymorphisms in the metabolic genes CYP1A1, CYP1A2, EPHX1, GSTM1, GSTT1, NAT2 and SULT1A1. A significant increased level of DNA aromatic adducts was found related to the fast oxidation-hydrolysis phenotype defined by the polymorphism I462V in CYP1A1, the allele A in IVS1-154C>A of CYP1A2 and the combination Tyrosine-Arginine for Y113H and H139R of EPHX1. Geometric means (adducts per 10(-9) normal nucleotides) were 2.17, 4.04 and 6.30 for slow, normal and fast phenotypes, respectively (P-trend = 0.01). Slow acetylation by NAT2 was associated with a significant decrease in adduct level; subjects with slow alleles *5A and *7A/B had in average 1.56 x 10(-9)adducts, as compared with 5.60 for those with normal NAT2 activity (P-value = 0.01). No association was seen with polymorphisms of other metabolic genes such as GSTM1, GSTT1 or SULT1A1. We concluded that the metabolic pathways of oxidation, hydrolysis and acetylation are relevant to the formation of bulky DNA adducts. This could suggest a potential involvement of aromatic compounds in the formation of such adducts; however, given lack of specificity of the post-labeling assay, a firm conclusion cannot be drawn.

Distribution of detoxifying genes polymorphism in Maharastrian population of central India

The present study is aimed at evaluating the genotype frequency of detoxifying genes such as GSTM1, GSTT1 and NQO1 in Maharastrian population of central India. The study revealed about 64.6% of GSTM1-positive and 35.4% GSTM1-null population. GSTT1-positive genotype was found to be 87.5% and GSTT1-null showed 12.5%. The NQO1 genotype of Maharastrian population showed 52.3% of C/C, 42.48% C/T and 5.18% T/T. The NQO1 of this population does not deviate from the expected Hardy-Weinberg equilibrium. The genotype frequencies GSTM1 and GSTT1 of the population when compared with other ethnic groups of Asia and Caucasians show distinct nature of Maharastrian population from other Asian and Caucasian population.

Analysis of Urinary Metabolites of Polycyclic Aromatic Hydrocarbons in Incineration Workers

Incineration workers are exposed to various pyrolysis products of organic materials, heavy metals and polycyclic aromatic hydrocarbons (PAHs). In this study, the exposure of incineration workers to PAHs was evaluated by measuring urinary metabolites of pyrene and naphthalene. The concentrations of urinary 1-hydroxypyrene (1OHP), a metabolite of pyrene, and 2-naphthol (2NP), a metabolite of naphthalene, were measured among 100 workers in 4 different types of incinerators, both before and after their work shifts. These incinerators were two old types, one modern type and one outdoors. The medians of urinary 1OHP of before and after the work shifts obtained from all workers were 0.067 and 0.044 mug/gCr, respectively; and the medians of urinary 2NP were 7.5 and 10.0 mug/gCr, respectively. A significant increase of 2NP after the work shift was found at one old incinerator. A significant decrease of metabolites was found at the other old incinerator. Significant correlations were found between urinary metabolites and cigarettes smoked per day. The effect of smoking on urinary metabolite levels was also important. Significant correlations were found between urinary 1OHP and 2NP levels in all workers. In multiple regression analysis smoking habit and incinerator type were found as significant factors. The improvement of the work environment, through decreasing exposure to both tobacco smoke and hazardous work shift-related substances, should be an occupational health aim.

Effect of Urban Traffic, Individual Habits, and Genetic Polymorphisms on Background Urinary 1-Hydroxypyrene Excretion

PURPOSE

Potential sources of exposure to polycyclic aromatic hydrocarbons (PAHs) and genetic polymorphisms were investigated in relation to their contribution to interindividual variation in baseline levels of urinary 1-hydroxypyrene (1-OHP) excretion in subjects without occupational exposure to PAHs.

METHODS

Urinary excretion of 1-OHP was measured in 114 subjects, including 48 women and 66 men. Questionnaire information was collected on possible environmental and individual sources of PAH exposure. A subset of 70 individuals also was evaluated for a single-nucleotide polymorphism (Ex7+295C-->T) in the cytochrome P-450 1A2 (CYP1A2) gene, and 61 of these also were evaluated for the glutathione transferase T1 (GSTT1) gene polymorphism.

RESULTS

1-OHP values did not show a significant seasonal variability and were unaffected by age; education; body mass index; smoking status, including passive smoking; or the C-->T base substitution in position 295 of exon 7 of the CYP1A2 gene. After reciprocal adjustment with logistic regression, living in a heavily trafficked urban area (odds ratio, 4.9; 95% confidence interval, 1.0-24.9), and frequent intake of grilled meat (odds ratio, 6.9; 95% confidence interval, 1.1-43.5) were significant predictors of background urinary 1-OHP levels of 0.50 microg/g creatinine or greater. Elevated risks also were associated with daily alcohol intake greater than 65 g and the nonnull GSTT1 genotype.

CONCLUSION

Our study shows that exposure to urban traffic, dietary habits, and the nonnull GSTT1 genotype may contribute to interindividual variation in background levels of 1-OHP urinary excretion in subjects without occupational exposure to PAHs.

Estimating exposure to polycyclic aromatic hydrocarbons: a comparison of survey, biological monitoring, and geographic information system-based methods

Our objective was to compare polycyclic aromatic hydrocarbon (PAH) exposure estimates based on survey, biological monitoring, and geographic information system (GIS) methods. The 304 participants in this study supplied a urine sample and completed questionnaires about exposure to potential PAH sources. We assayed urine samples for 1-hydroxypyrene-O-glucuronide (1-OHPG), the major metabolite of pyrene, a common PAH. We used a GIS to estimate traffic exhaust exposure using vehicle count data at the residence and workplace. The five subjects who reported smoking during the 48-hour period had median 1-OHPG concentrations 10-fold that of nonsmokers (1.6 versus 0.16 pmol/mL; P = 0.01). Among nonsmokers, those who reported eating grilled, roasted, or broiled meat had significantly higher 1-OHPG concentrations than those who did not reported eating meat prepared by these methods (0.25 versus 0.06 pmol/mL; P = 0.02). Nonsmokers who reported traveling on roads for > or =3 hours during the 48-hour period also had significantly higher 1-OHPG levels than those who traveled <3 hours (0.23 versus 0.11 pmol/mL; P = 0.03). 1-OHPG levels were also correlated with hours of secondhand smoke exposure among nonsmokers (P = 0.04). In this study, 1-OHPG urine concentrations were not associated with self-reported exposures to cooking smoke, wood burning, or traffic levels near the home or to traffic density or urban/rural status determined using a GIS. Self-reported indicators of residential proximity to high traffic volume were, however, associated with GIS traffic density measures.

Associations Between Exposure to Polycyclic Aromatic Hydrocarbons and Temporal Change of Urinary 1-Hydroxypyrene Levels in Taiwanese Coke-Oven Workers

OBJECTIVES

Our aim is to analyze the association between polycyclic aromatic hydrocarbon (PAH) exposure and the temporal change of urinary 1-hydroxypyrene (1-OHP).

METHODS

Two personal air samples, eight spot urine samples, and questionnaires were used to collect PAH exposure, urinary 1-OHP, demographic data, and environmental pollutants.

RESULTS

Topside-oven workers had significantly higher levels of PAH exposure and 1-OHP than side-oven workers. Urinary 1-OHP was a biomarker for PAH exposure. In topside-oven workers, the trend of 1-OHP increased sharply and reached the top in the sixth day after work and declined dramatically on days off. In side-oven workers, such a trend was not found, and those who smoked showed a slight increase in urinary 1-OHP levels on days off.

CONCLUSIONS

We suggest that the pattern of temporal change of urinary 1-OHP levels is different between topside-oven and side-oven workers.

Design issues in cross-sectional biomarkers studies: urinary biomarkers of PAH exposure and oxidative stress

Cross-sectional biomarker studies can provide a snapshot of the frequency and characteristics of exposure/disease in a population at a particular point in time and, as a result, valuable insights for delineating the multi-step association between exposure and disease occurrence. Three major issues should be considered when designing biomarker studies: selection of appropriate biomarkers, the assay (laboratory validity), and the population validity of the selected biomarkers. Factors related to biomarker selection include biological relevance, specificity, sensitivity, biological half-life, stability, and so on. The assay attributes include limit of detection, reproducibility/reliability, inter-laboratory variation, specificity, time, and cost. Factors related to the population validity include the frequency or prevalence of markers, greater inter-individual variation than intra-individual variation, intra-class correlation coefficients (ICC), association with potential confounders, invasiveness of specimen collection, and subject selection. Three studies are selected to demonstrate different features of cross-sectional biomarker studies: (1) characterizing the determinants of the biomarkers (study I: urinary PAH metabolites and environmental particulate exposure), (2) relationship of multiple biomarkers of exposure and effect (study II: relationship between urinary PAH metabolites and oxidative stress), and (3) evaluating gene-environmental interaction (study III: effect of genetic polymorphisms of GSTM1 on the association of green tea consumption and urinary 1-OHPG levels in shipbuilding workers).

DNA damage in T- and B-lymphocytes and granulocytes in emission inspection and incineration workers exposed to polycyclic aromatic hydrocarbons

In this study, we investigated by using comet assay the effects of polycyclic aromatic hydrocarbon (PAH) as a major factor on DNA damage of workers exposed to exhaust fumes. Twenty-four workers from three automobile emission inspection companies, 28 workers from a waste incinerating company, and 43 matched, unexposed healthy subjects were enrolled in the study. The mean values of 1-hydroxypyrene (1-OHP) in automobile emission inspection and waste incineration workers were 0.27+/-0.19 and 0.57+/-0.46 micromol/mol creatinine, respectively, and the mean values of 2-naphthol in automobile emission inspectors and waste incineration workers were 4.80+/-4.01 and 8.30+/-4.79 mol/mol creatinine, respectively. Significant difference in urinary metabolites, 1-hydroxypyrene and 2-naphthol was found between smokers and non-smokers in exposed groups and it may be due to the amounts of smoking cigarettes. In T-lymphocytes, DNA damage in control subjects, emission inspection workers and incineration workers were 1.42+/-0.22, 1.41+/-0.22 and 1.76+/-0.27, respectively. DNA damage of B-lymphocytes in the three groups showed the most significant differences of three cell types. The tail moments of the B-lymphocytes of control subjects, emission inspection and incineration workers were 1.40+/-0.27, 2.44+/-0.32 and 2.36+/-0.37, respectively. In granulocytes, DNA damage was also different, the tail moments being 2.72+/-0.59, 3.32+/-0.38 and 2.85+/-0.49, respectively. Although 1-OHP and 2-naphthol levels were statistically increased in smokers in workers exposed to PAHs, exposed smoking and non-smoking workers did not show any significantly difference in terms of Olive tail moments. Our results suggest that PAH causes single strand DNA breakage in human T- and B-lymphocytes, and granulocytes. A comparison of DNA damage in three groups showed that B-lymphocytes are useful target in the biomonitoring of human exposure.

Urinary PAH Metabolites Influenced by Genetic Polymorphisms of GSTM1 in Male Hospital Incinerator Workers

Hospital waste incinerator workers are exposed to various pyrolysis products including polycyclic aromatic hydrocarbons (PAHs). We evaluated their exposure by assessing urinary 1-hydroxypyrene glucuronide (1-OHPG), as an internal dose of PAH exposure. The potential effect of genetic polymorphisms of GSTM1/T1 involved in PAH metabolisms was also investigated. Pre- and post-shift samples were collected from 28 hospital incinerator workers. Urinary 1-OHPG was assayed by synchronous fluorescence spectroscopy (SFS) after immunoaffinity purification with the monoclonal antibody 8E11. Genotypes of GSTM1/T1 were assessed by PCR-based methods. Information on smoking habits and use of personal protective equipment were collected by means of a self-administered questionnaire. The Mann-Whitney test was used to compare group means of these biomarkers. Urinary 1-OHPG levels were similar in pre- and post-shift urine samples. The arithmetic mean concentrations of urinary 1-OHPG were 0.16 +/- 0.04 micromol/mol creatinine pre-shift and 0.19 +/- 0.09 micromol/mol creatinine post-shift, but urinary 1-OHPG levels were significantly higher in individuals with the GSTM1 null genotype than with the GSTM1 present genotype (p=0.05, by Mann-Whitney test). Our results suggest that the urinary 1-OHPG levels in hospital waste incinerator workers may be modified by the GSTM1 genotype, but these findings remain to be confirmed in future studies involving larger sample sizes.