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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.

Epidemiological studies conducted in metropolitan areas have demonstrated that exposure to environmental air pollution is associated with increases in mortality. Carcinogenic polycyclic aromatic hydrocarbons (c-PAHs) are the major source of genotoxic activities of organic mixtures associated with respirable particulate matter, which is a constituent of environmental air pollution. In this study,we wanted to evaluate the relationship between exposure to these genotoxic compounds present in the air and endogenous oxidative DNA damage in three different human populations exposed to varying levels of environmental air pollution. As measures of oxidative DNA damage we have determined 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and cyclic pyrimidopurinone N-1,N(2) malondialdehyde-2'-deoxyguanosine (M(1)dG) by the immunoslot blot assay from lymphocyte DNA of participating individuals. The level of endogenous oxidative DNA damage was significantly increased in individuals exposed to environmental air pollution compared to unexposed individuals from Kosice (8-oxodG adducts) and Sofia (M(1)dG adducts). However, there was no significant difference in the level of endogenous oxidative DNA and exposure to environmental air pollution in individuals from Prague (8-oxodG and M(1)dG adducts) and Kosice (M(1)dG adducts). The average level of M(1)dG adducts was significantly lower in unexposed and exposed individuals from Kosice compared to those from Prague and Sofia. The average level of 8-oxodG adducts was significantly higher in unexposed and exposed individuals from Kosice compared to those from Prague. A significant increasing trend according to the interaction of c-PAHs exposure and smoking status was observed in levels of 8-oxodG adducts in individuals from Kosice. However, no other relationship was observed for M(1)dG and 8-oxodG adduct levels with regard to the smoking status and c-PAH exposure status of the individuals. The conclusion that can be made from this study is that environmental air pollution may alter the endogenous oxidative DNA damage levels in humans but the effect appears to be related to the country where the individuals reside. Genetic polymorphisms of the genes involved in metabolism and detoxification and also differences in the DNA repair capacity and antioxidant status of the individuals could be possible explanations for the variation observed in the level of endogenous oxidative DNA damage for the different populations.

The EXPAH project was a molecular epidemiology study whose aims were to evaluate the hypothesis that polycyclic aromatic hydrocarbons (PAHs) are a major source of genotoxic activities of organic mixtures associated with air pollution. Biomarkers of exposure, effects and susceptibility, and oxidative DNA damage were measured in three PAH-exposed populations from Prague (Czech Republic), Kosice (Slovakia) and Sofia (Bulgaria). Control populations were included from each city. In total 356 individuals were enrolled. A questionnaire was used to determine life style/dietary factors. Ambient air exposure was measured by stationary monitoring, and personal exposure monitoring was also carried out. The characteristics of the population are described in this paper together with their personal exposure to carcinogenic PAHs (c-PAHs). The dose of c-PAH exposure was found to vary between the occupationally exposed (e.g. policemen and bus drivers) and the control populations in each country, and also varied from country to country.

The EXPAH project is a multicentre European study in which biomarkers of exposure, biomarkers of effect, genetic susceptibility and environmental factors were studied in populations exposed to differing levels of carcinogenic polycyclic aromatic hydrocarbons (c-PAHs). We describe here the relationships between the levels of DNA adducts (as biomarkers of exposure), the exposure to air pollution and smoking status. Lymphocyte bulky DNA adducts were significantly correlated with exposure when subjects were classified either by job description or by personal monitor measurements, and both bulky and benzo(a)pyrene (B[a]P) DNA adducts were also correlated with smoking status. These associations varied across the countries studied (Czech Republic, Slovakia, Bulgaria). Results from a multivariate analysis show that factors mainly contributing to bulky and B[a]P DNA adducts are age, smoking habit, country of origin and environmental exposure to c-PAHs. The B[a]P DNA adducts were more strongly associated with smoking status than with the environmental exposure to c-PAHs.

Pleural malignant mesothelioma (MM) is a rare but extremely aggressive cancer. The limited impact of standard therapeutic treatments on survival rates makes the identification of factors that increase the individual risk a leading priority. The high proportion of cases explained by exposure to asbestos has guided intervention policies to an effective ban of this compound from our environment. However, MM cannot be solely attributed to this agent, and the role of predisposing factors and their interaction with asbestos exposure is increasingly studied. The role of mEH, GSTM1, GSTT1, NAT2, and CYP1A1 genotypes in modulating susceptibility to MM was examined in a case-control study of 80 subjects with a confirmed diagnosis of MM and 255 controls. Subjects with low mEH activity showed a significantly increased risk of MM (OR, 2.51; 95% CI, 1.11-5.68). The association was stronger in the group with low asbestos exposure (OR, 7.83; 95% CI, 0.98-62.60). A significant increased risk of MM was also found in NAT2 fast acetylators (OR, 1.74; 95% CI, 1.02-2.96). The presence of synergisms between genotypes, i.e., mEH and NAT2 (LRT for heterogeneity p0.023), mEH and GSTM1 (LRT p0.061), and NAT2 and GSTM1 (LRT p0.049), combined with the interaction observed with exposure to asbestos, suggests the presence of gene-environment and gene-gene interactions in the development of MM, although the size of the study group does not allow to draw clearcut conclusions. Since genetic polymorphisms can also modify the extent of genetic damage occurring in subjects exposed to carcinogens, we measured the frequency of micronuclei in peripheral blood lymphocytes of a subgroup of MM cases. The limited number of cases (28) did not allow to observe significant effects. In conclusion, these results strengthen the hypothesis that individual susceptibility to MM can be modulated by the interaction between polymorphic genes involved in the metabolism and the intensity of asbestos exposure.

Because of the carcinogenicity of SV40 in rodents, and its possible distribution through the polio vaccine, many studies have been conducted to determine if there is an association between SV40 genomic infection and different types of cancer; sometimes, these studies included data on the prevalence of genomic infection in healthy subjects as secondary information. We reviewed all the studies that reported the prevalence of SV40 genomic infection in healthy subjects, tested by PCR based methods. The 20 articles considered here included 1103 samples from healthy subjects, with a prevalence of infection ranging from 0 to 25.6%, with high heterogeneity, and no association with the type of sample analyzed (Mantel–Haenszel OR: 0.74; 95% CI: 0.44–1.23). The wide variation in frequency pose problems in terms of study design; in fact, the representativeness of the samples used as controls in the published studies may be very limited. Larger studies on healthy subjects, tested for SV40 genomic infection at various genomic regions, conducted in different geographic areas, are needed.

DNA adducts measured in tissues are promising markers for identifying damage in organs that could be a target for carcinogens. Polymorphisms in genes involved in polycyclic aromatic hydrocarbons (PAHs) metabolism have been shown to modify the levels of PAH-DNA adducts in target tissues. In order to study the role of metabolic gene polymorphisms on DNA-adduct formation in sperm, we determined the GSTM1 genotype in a group of men in whom PAH-DNA adducts in sperm had been previously measured by immunofluorescence. The mean level of adducts in sperm was significantly higher in subjects carrying the homozygous deletion variant of GSTM1 than in subjects with a functional GSTM1 (mean fluorescence staining intensity: 1.62+/-0.62 versus 1.33+/-0.55; p=0.02). With respect to environmental factors, subjects who reported occupational exposure to PAHs and who carried the GSTM1 deletion had a significant increase in PAH-DNA adducts in sperm in comparison with subjects who were not exposed and had a functional GSTM1 (mean staining intensity: 1.83+/-0.67 versus 1.30+/-0.53; p=0.05), although among GSTM1-null subjects there was no significant difference with or without occupational exposure. This study presents for the first time the effect of a common polymorphism in a gene that metabolizes PAHs on DNA-adduct levels in sperm.

This study addresses the issue of appropriate allelic frequency estimates in epidemiological studies. Reasons for imprecise estimate of allele frequency may be population stratification, and lack of power of many published studies to define true allele frequencies in the general population. As an example of the lack of power of epidemiological studies, we plot the frequency of GSTM1 deletion versus sample size for the 79 studies from the GSEC pooled analysis. The estimate of allele frequency derived from small groups of controls deviates more from the true frequency than the estimate derived from larger studies. We discuss the possible consequences of not properly defining allele frequencies in the population. This may reflect on the conduct of association studies, on assessment of the effects of multigenic mechanisms, and on the determination of genetic diversity.

Exposure to high levels of environmental air pollution is known to be associated with an increased carcinogenic risk. The individual contribution to this risk derived from specific carcinogenic chemicals within the complex mixture of air pollution is less certain, but may be explored by the use of molecular epidemiological techniques. Measurements of biomarkers of exposure, of effect and of susceptibility provide information of potential benefit for epidemiological and cancer risk assessment. The application of such techniques has been mostly concerned in the past with the carcinogenic polycyclic aromatic hydrocarbons (c-PAHs) that are associated with particulate matter in air pollution, and has showed clear evidence of genotoxic effects, such as DNA adducts, chromosome aberrations (CA) and ras oncogene overexpression, in environmentally exposed Czech and Polish populations. We are currently extending these studies by an investigation of populations exposed to environmental pollution in three European countries, Czech Republic, Slovak Republic and Bulgaria. This pays particular attention to PAHs, but also investigates the extent of radically induced (oxidative) DNA damage in the exposed populations. Policemen, bus drivers and controls, who carried personal monitors to determine their exposures to PAHs have been studied, and blood and urine were collected. Antioxidant and dietary status were assessed in these populations. Stationary monitors were also used for ambient air monitoring. Amongst the parameters studied in the biological samples were: (a) exposure biomarkers, such as PAH adducts with DNA, p53 and p21(WAF1) protein levels, (b) oxidative DNA damage, (c) the biological effect of the exposure by measurement of chromosome damage by fluorescence in situ hybridisation (FISH) or conventional methods, and (d) polymorphisms in carcinogen metabolising and DNA repair enzymes. Repair ability was also measured by the Comet assay. In vitro systems are being evaluated to characterise the genotoxicity of the organic compounds adsorbed to air particles.

Severe DNA damage, which might prevent egg fertilization or the development of the embryo, could be a cause of infertility. In order to assess whether polycyclic aromatic hydrocarbon (PAH)-DNA adducts are an early marker of sperm genotoxicity and infertility, we studied 205 men consecutively recruited from 1 January to 30 May 2001 through the Infertility Clinic of the University of Milan (Italy), with morphological abnormalities in the sperm. No known causes of infertility were present in their female partners. Sperm were collected after 3–5 days of abstinence, fixed on polylysine slides, and frozen at −20 °C. PAH-DNA adducts were measured by immunofluorescence using a polyclonal antiserum. A questionnaire was filled out at the time of the visit, with demographic information, smoking and drinking habits, and occupational history. Data on PAH-DNA adducts were available for 182 men. The mean age of the subjects was 35.5±5.0 years; 38.6% of them were current smokers. PAH-DNA adducts were negatively correlated with the percentage of physiologic forms ( r =−0.18; P =0.016) and with abnormalities of the neck of the sperm cell ( r =−0.21; P ≥0.009), while they were positively correlated with morphological abnormalities of the head ( r =0.30; P >0.0001). Occupational exposure to PAH, but not smoking, was significantly associated with higher levels of PAH-DNA adducts. A significant negative association was observed between daily alcohol consumption and PAH-DNA adducts in sperm ( P =0.01). PAH-DNA adducts levels were significantly higher in infertile versus fertile men ( P =0.04). These results suggest a role for DNA damage in infertility.