Biomarkers of exposure and effect—interpretation in human risk assessment

The effect of exposure to carcinogenic polycyclic aromatic hydrocarbons adsorbed onto respirable air particles (PM2.5, diameter < 2.5 μm) on DNA adducts and chromosomal aberrations was repeatedly studied in Prague, Czech Republic, in groups of policemen working in the downtown area and in bus drivers. Personal exposure was evaluated using personal samplers during working shifts. DNA adducts were analyzed in lymphocytes by the 32P-postlabeling assay and chromosomal aberrations were analyzed by conventional cytogenetic analysis and fluorescent in situ hybridization (FISH). The impact of environmental pollution on DNA adducts and chromosomal aberrations was studied in a total of 950 subjects. Our results suggest that the environmental exposure of nonsmokers to concentrations higher than 1 ng benzo[a]pyrene/m3 represents a risk of DNA damage, as indicated by an increase in DNA adducts and the genomic frequency of translocations determined by FISH

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

<p>Abstract</p> <p>Background</p> <p>The results of a cross-sectional study aimed to evaluate whether genetic polymorphisms (biomarkers of susceptibility) for <it>CYP1A1</it>, <it>EPHX </it>and <it>GSTM1 </it>genes that affect polycyclic aromatic hydrocarbons (PAH) activation and detoxification might influence the extent of primary DNA damage (biomarker of biologically effective dose) in PAH exposed workers are presented. PAH-exposure of the study populations was assessed by determining the concentration of 1-hydroxypyrene (1OHP) in urine samples (biomarker of exposure dose).</p> <p>Methods</p> <p>The exposed group consisted of workers (n = 109) at a graphite electrode manufacturing plant, occupationally exposed to PAH. Urinary 1OHP was measured by HPLC. Primary DNA damage was evaluated by the alkaline comet assay in peripheral blood leukocytes. Genetic polymorphisms for <it>CYP1A1</it>, <it>EPHX</it> and <it>GSTM1</it> were determined by PCR or PCR/RFLP analysis.</p> <p>Results</p> <p>1OHP and primary DNA damage were significantly higher in electrode workers compared to reference subjects. Moreover, categorization of subjects as normal or outlier highlighted an increased genotoxic risk OR = 2.59 (CI95% 1.32–5.05) associated to exposure to PAH. Polymorphisms in <it>EPHX</it> exons 3 and 4 was associated to higher urinary concentrations of 1OHP, whereas none of the genotypes analyzed (<it>CYP1A1</it>, <it>EPHX</it>, and <it>GSTM1</it>) had any significant influence on primary DNA damage as evaluated by the comet assay.</p> <p>Conclusion</p> <p>The outcomes of the present study show that molecular epidemiology approaches (i.e. cross-sectional studies of genotoxicity biomarkers) can play a role in identifying common genetic risk factors, also attempting to associate the effects with measured exposure data. Moreover, categorization of subjects as normal or outlier allowed the evaluation of the association between occupational exposure to PAH and DNA damage highlighting an increased genotoxic risk.</p

Prenatal exposures and exposomics of asthma

This review examines the causal investigation of preclinical development of childhood asthma using exposomic tools. We examine the current state of knowledge regarding early-life exposure to non-biogenic indoor air pollution and the developmental modulation of the immune system. We examine how metabolomics technologies could aid not only in the biomarker identification of a particular asthma phenotype, but also the mechanisms underlying the immunopathologic process. Within such a framework, we propose alternate components of exposomic investigation of asthma in which, the exposome represents a reiterative investigative process of targeted biomarker identification, validation through computational systems biology and physical sampling of environmental medi

Occupational Exposure to PAHs Influence on Susceptibility to the X-ray Induced DNA Damage and Repair Capacity

Frequently nowadays present in ambient air the polycyclic aromatic hydrocarbons (PAHs) are considered as potential human carcinogens. The aim of our study was to investigate whether occupational exposure to environmental PAHs may affect cellular susceptibility to the induction of DNA damage and its repair efficacy. In this study, performed in Prague (Czech Republic), in two seasonal samplings (~ 100 subjects in each sampling) lymphocytes, isolated from the whole blood samples collected from two groups of subjects, traffic policemen exposed to PAHs and from control, were examined for cellular capacities. The challenging dose (2Gy) of X-rays was applied as DNA strands breaks. An alkaline version of Single Cell Gel Electrophoresis (SCGE) assay was used to study DNA damage in the cells before challenging treatment, immediately after exposure and after the incubation allowing the cells to complete the fast repair process. In each in vitro experiment, lymphocytes from the same pool of healthy male donors cells served as an internal standard. Significantly lower DNA repair efficiency of the X-rays induced damage was observed in PAHs-exposed donors (66.0% vs 76.4%, p<0.003 in the winter sampling; 57.7% vs 69.0%, p<0.004 in the summer sampling). Reduced repair efficiencies were observed in cells of donors exposed to PAHs after stratification according to smoking history (i.e. 54.2% vs 64.9%, p<0.05 in the smokers subgroup in summer sampling). Stratification according to genotype of donors was also done. Donors exposed to PAHs and heterozygous with the mutation in CYP1A1 gene (Ile/Val), despite much smaller number of such donors, exhibited significantly lower efficiency of repair (34.3% vs 62.7%, p<0.04). Donors belonging to the subgroup of slow acetylators (according to NAT2 genotype) who were exposed to PAHs were significantly less efficient in repair (64.7% vs 78.0%, p<0.006 in the winter sampling). Significantly reduced repair efficiencies were also observed for donors exposed to PAHs with deletion in GSTM1 gene (55.3% vs 66.9%, p<0.003 in the summer sampling). Our results illustrate, that application of X-rays dose to study DNA repair competence can be a good predictive biomarker in human monitoring studies. Obtained results imply that environmental exposure to polycyclic aromatic hydrocarbons via alteration of cellular DNA repair processes can result in effects harmful to human health. From our studies can be concluded that lowering of DNA repair efficacy increases amount of unrepaired DNA damage in lymphocytes of exposed to PAHs donors, that may elevate frequency of mutations and increase their risk of cancer

Effect of Vitamin Levels on Biomarkers of Exposure and Oxidative Damage - the EXPAH Study.

DNA adducts are markers of carcinogen exposure and of their biological effect; they have been shown to be related to mutagenesis, and therefore they could be a predictive biomarker of human cancer. The objective of this study was to assess if there is a relationship between vitamins A, C, and E, which are known to play a significant role as free radical scavengers and antioxidant agents, and biomarkers of genotoxicity and oxidative stress. Three hundred and fifty-six subjects from Czech Republic, Slovak Republic and Bulgaria, who completed a questionnaire on dietary information and had a measurement of plasma A, C, E vitamins, DNA adduct levels (benzo[a]pyrene (B[a]P) and bulky (DNA-Tot) DNA adducts) and oxidative damage (cyclic pyrimidopurinone N-1,N2 malondialdehyde-2 deoxyguanosine (M1dG) and 8-oxo-7,8-dihydro-2_deoxyguanosine (8-oxodG)) were analyzed. A significant inverse correlation was observed between plasma vitamin levels and both benzo[a]pyrene (B[a]P) and bulky DNA adducts. Vitamin A was also significantly inversely correlated with M1dG, a marker of oxidative damage. The associations were stronger in non-smokers than in smokers. Dietary intake of certain antioxidants such as vitamins is associated with reduced levels of markers of DNA damage (B[a]P and DNA-Tot) and oxidation (M1dG and 8-oxodG) measured in peripheral white blood cells. This could contribute to the protective role of such a dietary pattern on cancer risk. The protective effect of dietary vitamins is less evident in smokers