Air pollution and molecular changes in age-related diseases.

Assessment of the impact that air contaminants have on health is difficult as this is a complex mixture of substances that varies depending on the time and place. There are many studies on the association between air pollution and increased morbidity and mortality. Before the effect of polluted air is manifested at the level of the organs, an impact can be observed at the molecular level. These include some new biomarkers, like a shortening of the mean telomere length in DNA, dysregulation of gene expression caused by microRNA levels or a variation in the copy number of mitochondrial DNA. These changes may predispose individuals to premature development of age-related diseases and consequently to shortening of life. The common attribute, shared by changes at the molecular level and the development of diseases, is the presence of oxidative stress.

Transcriptome alterations in maternal and fetal cells induced by tobacco smoke.

OBJECTIVES: Maternal smoking has a negative effect on all stages of pregnancy. Tobacco smoke-related defects are well established at the clinical level; however, less is known about molecular mechanisms underlying these pathologic conditions. We thus performed a comprehensive analysis of transcriptome alterations induced by smoking in maternal and fetal cells. STUDY DESIGN: Samples of peripheral blood (PB), placenta (PL), and cord blood (UCB) were obtained from pregnant smokers (n = 20) and gravidas without significant exposure to tobacco smoke (n = 52). Gene expression profiles were assayed by Illumina Expression Beadchip v3 for analysis of 24,526 transcripts. The quantile method was used for normalization. Differentially expressed genes were analyzed in the Limma package and the P-values were corrected for multiple testing. Unsupervised hierarchical clustering was performed using average linkage and Euclidean distance. The enrichment of deregulated genes in biological processes was analyzed in DAVID database. RESULTS: Comparative analyses defined significant deregulation of 193 genes in PB, 329 genes in PL, and 49 genes in UCB of smokers. The deregulated genes were mainly related to xenobiotic metabolism, oxidative stress, inflammation, immunity, hematopoiesis, and vascularization. Notably, functional annotation of the affected genes identified several deregulated pathways associated with autoimmune diseases in the newborns of smokers. CONCLUSIONS: The study demonstrated maternal smoking causes significant changes in transcriptome of placental and fetal cells that deregulate numerous biological processes important for growth and development of the fetus. An activation of fetal CYP genes showed a limited ability of the placenta to modulate toxic effects of maternal tobacco use.

HVRII of mtDNA in cord blood cells of newborn children and in their saliva 10 years later.

Comparison of hypervariable region II nucleotide sequences of mitochondrial DNA obtained from cord blood cells and saliva cells of the same individual at birth and after ten years revealed a few differences at the so-called mutation hot spots (three transitions and three indels within the C-tract). The personal identity of samples was proved by short tandem repeat profiling. Comparison of individuals living in two regions that differ by air pollution, however, did not reveal statistically significantly increased number of mutations in the population from the region of poorer environmental conditions, although indicating such tendency.

The use of biomarkers for risk assessment: Reporting from the INTARESE/ENVIRISK Workshop in Prague.

This publication is a report on the workshop "The use of biomarkers for risk assessment" which took place in November 2007 in Prague, the Czech Republic. The main aim of the workshop was to bring together a broad international audience with a particular interest in the development and application of human biomonitoring (HBM) and biomarkers for environmental health research, and to provide a state-of-the art overview of the potential values and pitfalls of biomarkers in risk assessment. Throughout the presentations and the subsequent discussions, it was shown that human biomonitoring is a highly plastic and versatile tool for the unraveling of the link between contaminants in the environment and potentially associated health effects in the general population. Although it offers a means to integrate exposure through different environmental compartments, to integrate exposure over time, to include individual risk factors and genetic susceptibility, exposure biomarkers would greatly benefit from standardized, accurate and sensitive detection methods and toxicokinetic data. Effect biomarkers on the other hand need to be put into their relevant public health perspective, and well validated, mechanistically sound dose-response relationships are essential. New developments, such as in vitro assays and "-omics", may drastically improve our knowledge on the causal mechanisms behind environmental health associations and will allow for a more informed linkage of toxicological and epidemiological reality.

Frequency of chromosomal aberrations in Prague mothers and their newborns.

The capital city of Prague is one of the most polluted areas of the Czech Republic. The impact of air pollution on the level of chromosomal aberrations was systematically studied: analyses were performed using fluorescence in situ hybridization (FISH) with whole-chromosome painting for chromosomes #1 and #4. In the present study, we analyzed the levels of stable (one-way and two-way translocations) and unstable (acentric fragments) chromosomal aberrations in 42 mothers living in Prague and in their newborns. The average age of the mothers was 29 years (range, 20-40 years). Blood samples were collected from October 2007 to February 2008. The average levels of carcinogenic polycyclic aromatic hydrocarbons (c-PAHs) and benzo[a]pyrene (B[a]P) in respirable particles (PM2.5), as determined by stationary monitoring, were 21.0+/-12.3 ng/m(3) and 2.9+/-1.8 ng/m(3), respectively. We did not observe any effect of either c-PAH or B[a]P exposure on the genomic frequency of translocations (per 100 cells, F(G)/100) in either group due to their similar exposure during the winter months. The mean values of F(G)/100 representing stable aberrations were 0.09+/-0.13 vs 0.80+/-0.79 (p<0.001) for newborns vs mothers, indicating a significant increase of F(G)/100 with age. On the other hand, the frequency of unstable aberrations did not differ between the two groups. Our results demonstrate how the patterns of different types of aberration differed between newborns and mothers: we observed 64.3% unstable aberrations and 35.7% stable aberrations in newborns vs 19.7% and 80.3% in mothers, respectively. Our results indicate that after birth the frequencies of aberrations are very low and that the aberrations are represented mainly by acentric fragments. The changes observed in mothers show a shift to stable aberrations represented mainly by two-way translocations. The mother's age affected the level of aberrations in newborns: the group of children born to older mothers (31-40 years) had significantly increased F(G)/100 levels.

Effect of maternal tobacco smoke exposure on the placental transcriptome.

Smoking in pregnancy increases a woman's risk of preterm delivery resulting in serious neonatal health problems and chronic lifelong disabilities for the children (e.g., mental retardation, learning problems). To study the effects of tobacco smoke on the placental transcriptome, we performed gene expression profiling on placentas from women exposed to tobacco smoke in pregnancy (N = 12) and from those without significant exposure (N = 64). Gene expression profiles were determined by Illumina HumanRef-8 v2 Expression BeadChips with 18,216 gene probes. Microarray data were normalized by quantile method and filtered for a detection P-value <0.01. Differential gene expression was determined by moderated t-statistic. A linear model was fitted for each gene given a series of arrays using lmFit function. Multiple testing correction was performed using the Benjamini and Hochberg method. Abundant levels of transcripts were found for genes encoding placental hormones (CSH1, CSHL1), pregnancy-specific proteins (PSG3, PSG4, PAPPA), and hemoglobins (HBB, HBG, HBA). Comparative analysis of smokers vs nonsmokers revealed the differential expression of 241 genes (P < 0.05). In smoker cohort, we detected high up-regulation of xenobiotic genes (CYP1A1, CYP1B1, CYB5A, COX412), collagen genes (e.g., COL6A3, COL1A1, COL1A2), coagulation genes (F5, F13A1) as well as thrombosis-related genes (CD36, ADAMTS9, GAS6). In smokers, we identified deregulated genes that show tissue non-specific induction and may be considered as general biomarkers of tobacco smoke exposure. Further, we also found genes specifically deregulated in the exposed placentas. Functional annotation analysis suggested processes and pathways affected by tobacco smoke exposure that may represent molecular mechanisms of smoke-induced placental abnormalities.

Genetic polymorphisms influence the susceptibility of men to sperm DNA damage associated with exposure to air pollution.

The purpose of the present study was to investigate the impact of carcinogenic polycyclic aromatic hydrocarbons and volatile organic compounds on sperm quality in a group of city policemen in Prague during a period of increased concentrations of ambient air-pollutants (winter season) compared to a period of low exposure (spring). Polymorphisms in metabolic genes (CYP1A1, EPHX1, GSTM1, GSTP1, GSTT1), folic acid metabolism genes (MTR, MTHFR) and DNA repair genes (XRCC1, XPD6, XPD23, hOGG1) were evaluated in these men as potential modifiers of associations between air pollution exposure and changes in sperm quality. The study population was a group of 47 policemen working in the center of the city. Seasonal differences in exposure were verified by ambient and personal monitoring. Markers of sperm injury included semen volume, sperm concentration, sperm morphology, sperm motility, and sperm DNA damage measured with the sperm chromatin structure assay The sperm chromatin structure assay (SCSA) includes a measure of DNA damage called DNA Fragmentation Index (DFI). The % of cells with detectable DFI (detDFI) by this assay includes sperm with either medium or high DNA damage; the term hDFI is used to define the % of sperm with only high DNA damage. The assay also detects immature sperm defined by high density staining (HDS). No significant differences were found in any of the standard semen parameters between the sampling periods except for vitality of sperms. Both DFI and HDS were significantly higher in winter than in spring samples for all men and for non-smokers. At the bivariate level, significant associations between hDFI or detDFI and polymorphisms of the repair genes XRCC1, XPD6 and XPD23 were observed. In multivariate models, polymorphisms of the genes XPD6, XPD23 and CYP1A1MspI were associated with hDFI and HDS. Moreover, HDS was significantly associated with polymorphisms in GSTM1 gene.

Genetic variability of HVRII mtDNA in cord blood and respiratory morbidity in children.

Genetic polymorphisms were examined using direct sequencing of the hypervariable region II (HVRII) in the D-loop of mtDNA in the cord blood of 355 children living in two areas of the Czech Republic - the industrial district of Teplice and the agricultural district of Prachatice. The incidence of the most frequent nucleotide variants of HVRII, C150T (10.1%), T152C (19.7%), T195C (19.7%) and 309.nC (41.4% for 309.2C and 13.8% for 309.3C), and the respiratory morbidity at the ages of 0-2 years and 2-6 years were investigated, considering many other factors such as locality, gender, ethnicity, heating by coal in household, maternal age, asthma bronchiale, allergic rhinitis, pollinosis, conjunctivitis and maternal tobacco exposure during and after pregnancy. We found that the T195C transversion in HVRII is connected with an increased risk of early childhood (0-2 years) bronchitis (RR 1.38, p=0.034, 95% CI 1.04-1.85) and with increased risk of otitis media in children aged 2-6 years (RR 1.62, p=0.032, 95% CI 1.04-2.53). Another polymorphism, 309.nC, is associated with an increased risk of bronchitis in children aged 2-6 years (RR 1.46, p=0.030, 95% CI 1.04-2.06). The results indicate that genetic polymorphisms in mtDNA may be an important factor not only for various types of cancers and neurodegenerative diseases, but also for respiratory morbidity in children.

The impact of air pollution on the levels of micronuclei measured by automated image analysis.

The measurement of micronuclei (MN) in human peripheral blood lymphocytes is frequently used in molecular epidemiology as one of the preferred methods for assessing chromosomal damage resulting from environmental mutagen exposure. In the present study, we evaluated the effect of exposure to carcinogenic polycyclic aromatic hydrocarbons (c-PAHs), volatile organic compounds (VOC) and smoking on the frequency of MN in a group of 56 city policemen living and working in Prague. The average age of the participants was 34+/-6 years. The study was conducted on the same subjects in February and May 2007. The concentrations of air pollutants were obtained from personal and stationary monitoring. A statistically significant decrease in the levels of pollutants was observed in May when compared with February, with the exception of toluene levels measured by stationary monitoring. The frequency of MN was determined by the automatic image scoring (MetaSystems Metafer 4, version 3.2.1) of DAPI-stained slides. The results of the image analysis indicated a significant difference in the frequency of MN (mean levels 7.32+/-3.42 and 4.67+/-2.92, for February and May, respectively). Our study suggests that automatic image analysis of MN is a highly sensitive method for evaluating the effect of c-PAHs and confirms that there are no differences between smokers and nonsmokers. These results demonstrate the ability of c-PAHs to increase MN frequency, even if the exposure to c-PAHs occurred up to 60 days before the collection of biological material. Our work is the first human biomonitoring study focused on the measurement of MN by automated image analysis for assessing chromosomal damage as a result of environmental mutagen exposure.

Biomarkers of exposure to tobacco smoke and environmental pollutants in mothers and their transplacental transfer to the foetus. Part II. Oxidative damage.

Oxidative damage to macromolecules may have numerous negative health consequences. We measured oxidative damage to DNA, proteins and lipids in 80 newborns and 79 mothers, analyzed the effect of mother's tobacco smoke exposure on oxidative stress, and assessed correlations between oxidative stress markers and bulky and PAH (polycyclic aromatic hydrocarbons)-specific DNA adducts. Mean levels (+/-S.D.) of 8-oxodeoxyguanosine (8-oxodG) per 10(5) dG in the placenta were 2.85+/-0.78; we did not see a difference between 8-oxodG levels in newborns born to mothers exposed and unexposed to tobacco smoke. Protein carbonyl levels, a marker of protein oxidation, were comparable in the umbilical cord and in maternal venous blood plasma (17.4+/-3.2 and 17.6+/-4.2nmol/ml plasma in newborns and mothers, respectively, p=0.66). Lipid peroxidation measured as levels of 15-F(2t)-isoprostane (15-F(2t)-IsoP) in plasma was significantly higher in newborns than in mothers (362+/-129 and 252+/-130pg/ml in newborns and mothers, respectively, p<0.001). We did not find any effect of tobacco smoke exposure on either biomarker in any group. Levels of both protein carbonyls and 15-F(2t)-IsoP in cord blood significantly correlated with those in maternal plasma (p<0.001). 8-oxodG levels positively correlated with plasma carbonyls in cord plasma, as well as with cotinine levels (marker of tobacco smoke exposure) in maternal plasma. 8-oxodG levels also correlated with bulky DNA adducts in lymphocyte DNA of newborns and mothers and with PAH-DNA adducts in the placenta. Our results showed higher lipid peroxidation in newborns than in mothers, close correlation of analyzed oxidative stress markers between newborns and mothers, and a relationship between oxidative stress and induction of DNA adducts.

Biomarkers of exposure to tobacco smoke and environmental pollutants in mothers and their transplacental transfer to the foetus. Part I: bulky DNA adducts.

(32)P-postlabelling and PAH-ELISA using the antiserum #29 were employed to analyze DNA adducts in venous and umbilical cord blood and the placenta of 79 mothers giving birth to 80 living babies in Prague (Czech Republic). Ambient air exposure was measured by stationary measurements of basic air pollutants (PM2.5, c-PAHs) during the entire pregnancy. Tobacco smoke exposure was assessed by questionnaire data and by plasma cotinine levels. The total DNA adduct levels in the lymphocytes of mothers and newborns were elevated by 30-40% (p<0.001) compared with the placenta. B[a]P-like DNA adduct (adduct with the identical chromatographic mobility on TLC as major BPDE derived DNA adduct) levels were elevated in the blood of mothers compared with the placenta and the blood of newborns (p<0.05 and p<0.01). In tobacco smoke-exposed mothers, higher DNA adduct levels in the blood of mothers and newborns compared with the placenta were found (p<0.001), whereas the total and B[a]P-like adduct levels were comparable in the blood of mothers and newborns. B[a]P-like adducts were elevated in the blood of mothers unexposed to tobacco smoke compared with that of corresponding newborns and the placenta (p<0.01). Total and B[a]P-like DNA adducts were increased in the placenta of tobacco smoke-exposed compared with unexposed mothers (p<0.001 and p<0.01). In lymphocytes of tobacco smoke-exposed mothers, the comparison of total adduct levels (1.18+/-0.67 vs. 0.92+/-0.28) and B[a]P-like DNA adducts (0.22+/-0.12 adducts/10(8) nucleotides vs. 0.15+/-0.06 adducts/10(8) nucleotides) with newborns indicated a 30-40% increase of adducts in mothers. Almost equal PAH-DNA adduct levels were detected by anti-BPDE-DNA ELISA in the placenta of tobacco smoke-exposed and -unexposed mothers. Our results suggest a protective effect of the placental barrier against the genotoxic effect of some tobacco smoke components between the circulation of mother and child. We found a correlation between adduct levels in the blood of mothers and newborns.

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.

Temporal variation in the genotoxic potential of urban air particulate matter.

The main aim of this study was to compare the genotoxic potential of organic extracts from urban air particles collected in three different sampling periods in the center of Prague (Czech Republic). For this purpose, we analyzed the DNA adduct forming activity of extractable organic matter (EOM) from urban air particles <10 microm (PM10) in the human hepatoma cell line HepG2. DNA adducts were analyzed by (32)P-postlabelling with nuclease P1 enrichment. PM10 concentrations were 36.9 microg/m(3), 62.6mug/m(3) and 39.0 microg/m(3), in summer 2000, winter 2001 and winter 2005, respectively. The corresponding EOM contents were 5.0 microg/m(3) (13.9% of PM10), 14.9 microg/m(3) (23.8%) and 6.7 microg/m(3) (17.2%). The total DNA adduct levels induced by 10 microg EOM/ml were 4.7, 19.5 and 37.2 adducts/10(8) nucleotides in summer 2000, winter 2001 and winter 2005, respectively. However, when the EOM quantities per cubic meter of air were taken into consideration, the summer sample exhibited a 10-fold lower genotoxicity than did those of winter, while the difference between the winter samples was not significant: 23.4 in summer 2000, 291 in winter 2001 and 249 in winter 2005 (in relative units). Although the PM10 concentration in air and the EOM content in particles in winter 2005 were significantly lower than in winter 2001, the genotoxic potential of the ambient air in these samples was almost equal. There were significant positive correlations between the B[a]P and c-PAH content in EOM from various sampling periods and the total DNA adduct levels detected in the EOM-treated samples. These findings support the hypothesis that the B[a]P and c-PAH content in EOM is the most important factor that determines its genotoxic potential. Thus, estimating the genotoxic potential of the ambient air and predicting health risk should be based mainly on the c-PAH concentration and the biological activity of the extracts, while the mass of particles and the EOM content do not seem to be crucial determinants of ambient air genotoxicity.

Biomarkers of air pollution exposure--a study of policemen in Prague.

The effect of exposure to organic compounds adsorbed onto respirable air particles (<2.5microm) on DNA adducts in lymphocytes was studied in a group of non-smoking policemen (N=109, aged 35+/-0.9 years) working in the downtown area of Prague and spending >8h daily outdoors. Personal exposure to carcinogenic polycyclic aromatic hydrocarbons (c-PAHs) adsorbed on respirable particles was monitored in each subject for 48h before biological sampling. DNA adducts were analyzed by a (32)P-postlabelling assay, and total DNA adduct levels and B[a]P-like spots were determined. Further biomarkers included cotinine levels in urine to control for exposure to tobacco smoke, plasma levels of vitamins A, E and C and polymorphisms of metabolic genotypes (GSTM1, GSTP1, GSTT1, CYP 1A1-Msp I and Ile/Val, MTHFR, MS), DNA repair genotypes (XRCC1, hOGG1 and XPD exons 6 and 23) and the p53 gene (p53 Msp I and BstU I). All the biomarkers of exposure and effect were analyzed repeatedly during a period of one year at 2-3 month intervals (January, March, June, September 2004) to cover periods with high (winter) and low (summer) levels of air pollution. The highest personal exposure to c-PAHs was found in January (8.1+/-8.8ng/m(3)), while the other three sampling periods exhibited 3-4-fold lower c-PAH exposure. The total DNA adducts were only slightly elevated in January (2.08+/-1.60) compared to March (1.66+/-0.65), June (1.96+/-1.73) and September (1.77+/-1.77). B[a]P-like DNA adducts, however, were significantly higher in January than in the March and June sampling periods (0.26+/-0.14 vs. 0.19+/-0.12 and 0.22+/-0.13, respectively; p<0.0001 and p=0.017) indicating that c-PAH exposure probably plays a crucial role in DNA adduct formation in lymphocytes. No effect of individual metabololic or DNA repair genotypes on DNA adduct levels was observed. However, the combination of two genotypes encoding enzymes metabolizing c-PAHs - CYP 1A1 and GSTM1 - was associated with the levels of total and B[a]P-like DNA adducts under conditions of increased exposure to c-PAHs. Our study suggests that DNA adducts in the lymphocytes of subjects exposed to increased c-PAH levels are an appropriate biomarker of a biologically effective dose, directly indicating whether or not the extent of exposure to these compounds is related to an increased mutagenic and carcinogenic risk.

In vitro genotoxicity of PAH mixtures and organic extract from urban air particles part II: human cell lines.

Principal aims of this study were at first, to find a relevant human derived cell line to investigate the genotoxic potential of PAH-containing complex mixtures and second, to use this cell system for the analysis of DNA adduct forming activity of organic compounds bound onto PM10 particles. Particles were collected by high volume air samplers during summer and winter periods in three European cities (Prague, Kosice, and Sofia), representing different levels of air pollution. The genotoxic potential of extractable organic matter (EOM) was compared with the genotoxic potential of individual carcinogenic polycyclic aromatic hydrocarbons (c-PAHs) as well as their artificial mixtures. Metabolically competent human hepatoma HepG2 cells, confluent cultures of human diploid lung fibroblasts (HEL), and the human monocytic leukemia cell line THP-1 were used as models. DNA adducts were analyzed by (32)P-postlabeling. The total DNA adduct levels induced in HepG2 cells after exposure to EOMs were higher than in HEL cells treated under the same conditions (15-190 versus 2-15adducts/10(8) nucleotides, in HepG2 and HEL cells, respectively). THP-1 cells exhibited the lowest DNA adduct forming activity induced by EOMs (1.5-3.7adducts/10(8) nucleotides). A direct correlation between total DNA adduct levels and c-PAH content in EOM was found for all EOMs in HepG2 cells incubated with 50microg EOM/ml (R=0.88; p=0.0192). This correlation was even slightly stronger when B[a]P content in EOMs and B[a]P-like adduct spots were analyzed (R=0.90; p=0.016). As THP-1 cells possess a limited metabolic capacity for most c-PAHs to form DNA reactive intermediates and are also more susceptible to toxic effects of PAHs and various EOM components, this cell line seemed to be an inappropriate system for genotoxicity studies of PAH-containing complex mixtures. The seasonal variability of genotoxic potential of extracts was stronger than variability among the three localities studied. In HepG2 cells, the highest DNA adduct levels were induced by EOM collected in Prague in the winter period, followed by Sofia and Kosice. However, in the summer sampling period, the order was quite opposite: Kosice>Sofia>Prague. When the EOM content per m(3) of air was taken into consideration in order to compare real exposures of humans to genotoxic compounds in all three localities, extracts from respirable dust particles collected in Sofia exhibited the highest genotoxicity regardless of the sampling period. The results indicate that most of DNA adducts detected in cells incubated with EOMs have their origin in low concentrations of c-PAHs representing 0.03-0.17% of EOM total mass. Finally, our results suggest that HepG2 cells have a metabolic capacity for PAHs similar to human hepatocytes and represent therefore the best in vitro model for investigating the genotoxic potential of complex mixtures containing PAHs among the three cell lines tested in this study.

In vitro genotoxicity of PAH mixtures and organic extract from urban air particles part I: acellular assay.

Acellular assay of calf thymus DNA+/-rat liver microsomal S9 fraction coupled with (32)P-postlabelling was used to study the genotoxic potential of organic compounds bound onto PM10 particles collected in three European cities-Prague (CZ), Kosice (SK) and Sofia (BG) during summer and winter periods. B[a]P alone induced DNA adduct levels ranging from 4.8 to 768 adducts/10(8) nucleotides in the concentration dependent manner. However, a mixture of 8 c-PAHs with equimolar doses of B[a]P induced 3.7-757 adducts/10(8) nucleotides, thus suggesting the inhibition of DNA adduct forming activity by interaction among various PAHs. Comparison of DNA adduct levels induced by various EOMs indicates higher variability among seasons than among localities. DNA adduct levels for Prague collection site varied from 19 to 166 adducts/10(8) nucleotides, for Kosice from 22 to 85 and for Sofia from 6 to 144 adducts/10(8) nucleotides. Bioactivation with S9 microsomal fraction caused 2- to 7-fold increase in DNA adduct levels compared to -S9 samples, suggesting a crucial role of indirectly acting genotoxic EOM components, such as PAHs. We have demonstrated for the first time a significant positive correlation between B[a]P content in EOMs and total DNA adduct levels detected in the EOM treated samples (R=0.83; p=0.04). These results suggest that B[a]P content in EOM is an important factor for the total genotoxic potential of EOM and/or B[a]P is a good indicator of the presence of other genotoxic compounds causing DNA adducts. Even stronger correlation between the content of genotoxic compounds in EOMs and total DNA adduct levels detected (R=0.94; p=0.005) was found when eight c-PAHs were taken into the consideration. Our findings support a hypothesis that a relatively limited number of EOM components is responsible for a major part of its genotoxicity detectable as DNA adducts by (32)P-postlabelling.

Chromosomal aberrations and SCEs as biomarkers of cancer risk.

Previous studies have suggested that the frequency of chromosomal aberrations (CAs), but not of sister chromatid exchanges (SCEs), predicts cancer risk. We have further examined this relationship in European cohorts comprising altogether almost 22,000 subjects, in the framework of a European collaborative project (CancerRiskBiomarkers). The present paper gives an overview of some of the results of the project, especially as regards CAs and SCEs. The results confirm that a high level of CAs is associated with an increased risk of cancer and indicate that this association does not depend on the time between CA analysis and cancer detection, i.e., is obviously not explained by undetected cancer. The present evidence indicates that both chromatid-type and chromosome-type CAs predict cancer, even though some data suggest that chromosome-type CAs may have a more pronounced predictive value than chromatid-type CAs. CA frequency appears to predict cancers at various sites, although there seems to be a particular association with gastrointestinal cancers. SCE frequency does not appear to have cancer predictive value, at least partly due to uncontrollable technical variation. A number of genetic polymorphisms of xenobiotic metabolism, DNA repair, and folate metabolism affect the level of CAs and might collectively contribute to the cancer predictivity of CAs. Other factors that may influence the association between CAs and cancer include, e.g., exposure to genotoxic carcinogens and internal generation of genotoxic species. Although the association between CA level and cancer is seen at the group level, an association probably also exists for the individual, although it is not known if an individual approach could be feasible. However, group level evidence should be enough to support the use of CA analysis as a tool in screening programs and prevention policies in occupational and environmental health.

Genome-wide differential gene expression in children exposed to air pollution in the Czech Republic.

The Teplice area in the Czech Republic is a mining district where elevated levels of air pollution including airborne carcinogens, have been demonstrated, especially during winter time. This environmental exposure can impact human health; in particular children may be more vulnerable. To study the impact of air pollution in children at the transcriptional level, peripheral blood cells were subjected to whole genome response analysis, in order to identify significantly modulated biological pathways and processes as a result of exposure. Using genome-wide oligonucleotide microarrays, we investigated differential gene expression in children from the Teplice area (n=23) and compared them with children from the rural control area of Prachatice (n=24). In an additional approach, individual gene expressions were correlated with individual peripheral blood lymphocyte micronuclei frequencies, in order to evaluate the linkage of individual gene expressions with an established biomarker of effect that is representative for increased genotoxic risk. Children from the Teplice area showed a significantly higher average micronuclei frequency than Prachatice children (p=0.023). For considerable numbers of genes, the expression differed significantly between the children from the two areas. Amongst these genes, considerable numbers of genes were observed to correlate significantly with the frequencies of micronuclei. The main biological process that appeared significantly affected overall was nucleosome assembly. This suggests an effect of air pollution on the primary structural unit of the condensed DNA. In addition, several other pathways were modulated. Based on the results of this study, we suggest that transcriptomic analysis represents a promising biomarker for environmental carcinogenesis.

[Parental smoking and exposure of pre-school children to tobacco smoke]. / Kourení rodicu a expozice predskolních detí tabákovému kouri.

BACKGROUND: During studies on the health of children aged 3 or 4.5 years in Teplice and Prachatice districts of the Czech Republic, we focused also on the extent of smoking in the families and exposure of children to environmental tobacco smoke. METHODS AND RESULTS: In 1128 questionnaires administered to mothers of children born in 1994-1998, 35.6% of mothers indicated that they smoked and 48.9% of fathers/partners (N = 1075) were smokers. Including other family members, there were 41.6% families without any smoker, 30.1% of families with one smoker and 24% families with two smokers (out of 1061 households). Urine samples of 523 pairs of mothers and children (aged 4.5 years) were assayed for cotinine using a RIA radioimmunoassay. Concentration of cotinine was higher than 500 ng cotinine/mg creatinine (the cut-off value for smoking) in 199 of 523 mothers (38%). Exposure of children to environmental tobacco smoke (cotinine levels over 20ng/mg creatinine) was detected in 48.2% of 523 children. There were more children with cotinine levels over 20 ng in Teplice (59.2% of 287 children) than in Prachatice district (34.7% of 236 children). CONCLUSIONS: Cotinine levels in child's urine were significantly positively associated with maternal cotinine levels as well as with smoking of mother and father, and were lower in children visiting kindergarten.