Gender differences in cadmium and cotinine levels in prepubertal children.

Susceptibility to environmental stressors has been described for fetal and early childhood development. However, the possible susceptibility of the prepubertal period, characterized by the orchestration of the organism towards sexual maturation and adulthood has been poorly investigated and exposure data are scarce. In the current study levels of cadmium (Cd), cotinine and creatinine in urine were analyzed in a subsample 216 children from 12 European countries within the DEMOCOPHES project. The children were divided into six age-sex groups: boys (6-8 years, 9-10 years and 11 years old), and girls (6-7 years, 8-9 years, 10-11 years). The number of subjects per group was between 23 and 53. The cut off values were set at 0.1 µg/L for Cd, and 0.8 µg/L for cotinine defined according to the highest limit of quantification. The levels of Cd and cotinine were adjusted for creatinine level. In the total subsample group, the median level of Cd was 0.180 µg/L (range 0.10-0.69 µg/L), and for cotinine the median wet weight value was 1.50 µg/L (range 0.80-39.91 µg/L). There was no significant difference in creatinine and cotinine levels between genders and age groups. There was a significant correlation between levels of cadmium and creatinine in all children of both genders. This shows that even at such low levels the possible effect of cadmium on kidney function was present and measurable. An increase in Cd levels was evident with age. Cadmium levels were significantly different between 6-7 year old girls, 11 year old boys and 10-11 year old girls. As there was a balanced distribution in the number of subjects from countries included in the study, bias due to data clustering was not probable. The impact of low Cd levels on kidney function and gender differences in Cd levels needs further investigation.

Interpreting biomarker data from the COPHES/DEMOCOPHES twin projects: Using external exposure data to understand biomarker differences among countries.

In 2011 and 2012, the COPHES/DEMOCOPHES twin projects performed the first ever harmonized human biomonitoring survey in 17 European countries. In more than 1800 mother-child pairs, individual lifestyle data were collected and cadmium, cotinine and certain phthalate metabolites were measured in urine. Total mercury was determined in hair samples. While the main goal of the COPHES/DEMOCOPHES twin projects was to develop and test harmonized protocols and procedures, the goal of the current paper is to investigate whether the observed differences in biomarker values among the countries implementing DEMOCOPHES can be interpreted using information from external databases on environmental quality and lifestyle. In general, 13 countries having implemented DEMOCOPHES provided high-quality data from external sources that were relevant for interpretation purposes. However, some data were not available for reporting or were not in line with predefined specifications. Therefore, only part of the external information could be included in the statistical analyses. Nonetheless, there was a highly significant correlation between national levels of fish consumption and mercury in hair, the strength of antismoking legislation was significantly related to urinary cotinine levels, and we were able to show indications that also urinary cadmium levels were associated with environmental quality and food quality. These results again show the potential of biomonitoring data to provide added value for (the evaluation of) evidence-informed policy making.

A pilot study on the feasibility of European harmonized human biomonitoring: Strategies towards a common approach, challenges and opportunities.

In 2004 the European Commission and Member States initiated activities towards a harmonized approach for Human Biomonitoring surveys throughout Europe. The main objective was to sustain environmental health policy by building a coherent and sustainable framework and by increasing the comparability of data across countries. A pilot study to test common guidelines for setting up surveys was considered a key step in this process. Through a bottom-up approach that included all stakeholders, a joint study protocol was elaborated. From September 2011 till February 2012, 17 European countries collected data from 1844 mother-child pairs in the frame of DEMOnstration of a study to COordinate and Perform Human Biomonitoring on a European Scale (DEMOCOPHES).(1) Mercury in hair and urinary cadmium and cotinine were selected as biomarkers of exposure covered by sufficient analytical experience. Phthalate metabolites and Bisphenol A in urine were added to take into account increasing public and political awareness for emerging types of contaminants and to test less advanced markers/markers covered by less analytical experience. Extensive efforts towards chemo-analytical comparability were included. The pilot study showed that common approaches can be found in a context of considerable differences with respect to experience and expertize, socio-cultural background, economic situation and national priorities. It also evidenced that comparable Human Biomonitoring results can be obtained in such context. A European network was built, exchanging information, expertize and experiences, and providing training on all aspects of a survey. A key challenge was finding the right balance between a rigid structure allowing maximal comparability and a flexible approach increasing feasibility and capacity building. Next steps in European harmonization in Human Biomonitoring surveys include the establishment of a joint process for prioritization of substances to cover and biomarkers to develop, linking biomonitoring surveys with health examination surveys and with research, and coping with the diverse implementations of EU regulations and international guidelines with respect to ethics and privacy.

Transcriptomic network analysis of micronuclei-related genes: a case study.

Mechanistically relevant information on responses of humans to xenobiotic exposure in relation to chemically induced biological effects, such as micronuclei (MN) formation can be obtained through large-scale transcriptomics studies. Network analysis may enhance the analysis and visualisation of such data. Therefore, this study aimed to develop a 'MN formation' network based on a priori knowledge, by using the pathway tool MetaCore. The gene network contained 27 genes and three gene complexes that are related to processes involved in MN formation, e.g. spindle assembly checkpoint, cell cycle checkpoint and aneuploidy. The MN-related gene network was tested against a transcriptomics case study associated with MN measurements. In this case study, transcriptomic data from children and adults differentially exposed to ambient air pollution in the Czech Republic were analysed and visualised on the network. Six genes from the network, i.e. BAX, DMNT1, PCNA, HIC1, p21 and CDC20, were retrieved. Based on these six genes and in combination with p53 and IL-6, a dedicated network was created. This dedicated network is possibly suited for the development of a reporter gene assay that could be used to screen populations complementary to the current MN test assay. In conclusion, we have shown that network analysis of transcriptomics data in relation to the formation of MN is possible and provides a novel mechanistic hypothesis by indicating which genes are regulated and influence others.

Typical signature of DNA damage in white blood cells: a pilot study on etheno adducts in Danish mother-newborn child pairs.

The impact of DNA damage commonly thought to be involved in chronic degenerative disease causation is particularly detrimental during fetal development. Within a multicenter study, we analyzed 77 white blood cell (WBC) samples from mother-newborn child pairs to see if imprinting of DNA damage in mother and newborn shows a similar pattern. Two adducts 1,N(6)-ethenodeoxyadenosine (epsilondA) and 3,N(4)-ethenodeoxycytidine (epsilondC) were measured by our ultrasensitive immunoaffinity (32)P-post-labeling method. These miscoding etheno-DNA adducts are generated by the reaction of lipid peroxidation (LPO) end products such as 4-hydroxy-2-nonenal with DNA bases. Mean epsilondA and epsilondC levels when expressed per 10(9) parent nucleotides in WBC-DNA from cord blood were 138 and 354, respectively; in maternal WBC-DNA, the respective values were 317 and 916. Thus, the DNA-etheno adduct levels were reliably detectable and about two times lower in child cord blood, the difference being significant at P < 0.0004. Analysis of epsilondA and epsilondC levels in cord versus maternal blood WBC showed strong positive correlations (R(2) approximately 0.9, P < 0.00001). In conclusion, LPO-induced DNA damage arising from endogenous reactive aldehydes in WBC of both mother and newborn can be reliably assessed by epsilondA and epsilondC as biomarkers. The high correlation of etheno adduct levels in mother and child WBC suggests that a typical signature of DNA damage is induced similarly in fetus and mother. Prospective cohort studies have to reveal whether these two WBC-DNA adducts could serve as risk indicator for developing hematopoietic cancers and other disorders later in life.

Increased micronuclei and bulky DNA adducts in cord blood after maternal exposures to traffic-related air pollution.

Exposure to traffic-related air pollution in urban environment is common and has been associated with adverse human health effects. In utero exposures that result in DNA damage may affect health later in life. Early effects of maternal and in utero exposures to traffic-related air pollution were assessed through the use of validated biomarkers in blood cells from mother-newborn pairs. A cross-sectional biomonitoring study with healthy pregnant women living in the Greater Copenhagen area, Denmark, was conducted. Bulky DNA adducts and micronuclei (MN) were measured in blood from 75 women and 69 umbilical cords, concurrently collected at the time of planned Caesarean section. Modeled residential traffic density, a proxy measure of traffic-related air pollution exposures, was validated by indoor levels of nitrogen dioxide and polycyclic aromatic hydrocarbons in 42 non-smoking homes. DNA adduct levels were similar and positively correlated in maternal and cord blood (1.40 vs. 1.37 n/10(8) nucleotides; r=0.99; p<0.01). Maternal MN frequencies were significantly associated with age (p<0.01), and higher than those of the newborns (7.0 vs. 3.2 MN per 1000 binucleated cells). Adduct levels were highest among mother-newborn pairs who lived near medium-traffic-density (>400-2500 vehicle km/24h; p<0.01) places. MN frequencies among newborns from women who lived at high-traffic-density homes (>2500 vehicle km/24h) were significantly increased (p=0.02). This trend remained after adjusting for potential confounders and effect modifiers. For the first time increased bulky DNA adducts and MN in cord blood after maternal exposures to traffic-related air pollution are found, demonstrating that these transplacental environmental exposures induce DNA damage in newborns. Given that increased DNA damage early in life indicate an increased risk for adverse health effects later in life, these findings justify intervention of pregnant women.

Genomic damage in children accidentally exposed to ionizing radiation: a review of the literature.

During the last decade, our knowledge of the mechanisms by which children respond to exposures to physical and chemical agents present in the environment, has significantly increased. Results of recent projects and programmes focused on children's health underline a specific vulnerability of children to environmental genotoxicants. Environmental research on children predominantly investigates the health effects of air pollution while effects from radiation exposure deserve more attention. The main sources of knowledge on genome damage of children exposed to radiation are studies performed after the Chernobyl nuclear plant accident in 1986. The present review presents and discusses data collected from papers analyzing genome damage in children environmentally exposed to ionizing radiation. Overall, the evidence from the studies conducted following the Chernobyl accident, nuclear tests, environmental radiation pollution and indoor accidental contamination reveals consistently increased chromosome aberration and micronuclei frequency in exposed than in referent children. Future research in this area should be focused on studies providing information on: (a) effects on children caused by low doses of radiation; (b) effects on children from combined exposure to low doses of radiation and chemical agents from food, water and air; and (c) specific effects from exposure during early childhood (radioisotopes from water, radon in homes). Special consideration should also be given to a possible impact of a radiochemical environment to the development of an adaptive response for genomic damage. Interactive databases should be developed to provide integration of cytogenetic data, childhood cancer registry data and information on environmental contamination. The overall aim is to introduce timely and efficient preventive measures, by means of a better knowledge of the early and delayed health effects in children resulting from radiation exposure.

Laboratory work and pregnancy outcomes: a study within the National Birth Cohort in Denmark.

AIMS: To examine pregnancy outcomes in women doing laboratory work. METHODS: Using data from the Danish National Birth Cohort (1997-2003), the authors conducted a prospective cohort study of 1025 female laboratory technicians and 8037 female teachers (as reference). The laboratory technicians were asked about laboratory work tasks during pregnancy in an interview (at around 16 weeks of gestation). Pregnancy outcomes were obtained by linking the cohort to the national registers. Hazard ratios (HRs) of late fetal loss and diagnosing of congenital malformations were calculated by using Cox regression, and odds ratios (ORs) of preterm birth and small for gestational age were calculated by using logistic regression. RESULTS: Overall, there were no significant differences in pregnancy outcomes between laboratory technicians and teachers. However, we found that laboratory technicians working with radioimmunoassay or radiolabelling had an increased risk of preterm birth (OR = 2.2, 95% CI 0.8 to 6.2 for radioimmunoassay, and OR = 1.9, 95% CI 0.8 to 4.6 for radiolabelling) and "major" malformations (HR = 2.1, 95% CI 1.0 to 4.7 for radioimmunoassay, and HR = 1.8, 95% CI 0.9 to 3.7 for radiolabelling). The ORs of preterm birth doubled for women working with these tasks every day or several times a week. When an exposure matrix was applied, an increased risk of "major" malformations for exposure to organic solvents was seen. CONCLUSIONS: The results did not indicate any high risk of reproductive failures in laboratory technicians in general. Exposure to radioisotopes may carry a high risk of preterm birth and congenital malformations. This finding deserves further investigation.

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.

Chromosomal aberrations in lymphocytes predict human cancer: a report from the European Study Group on Cytogenetic Biomarkers and Health (ESCH).

Chromosomal aberrations (CAs), sister chromatid exchanges (SCEs), and micronuclei (MN) in peripheral blood lymphocytes have for decades been used as cytogenetic biomarkers to survey genotoxic risks in the work environment. The conceptual basis for this application has been the idea that increased cytogenetic damage reflects an enhanced cancer risk. Nordic and Italian cohorts have been established to evaluate this hypothesis, and analyses presented previously have shown a positive trend between CA frequency and increased cancer risk. We now report on a pooled analysis of updated data for 3541 subjects examined for CAs, 2703 for SCEs, and 1496 for MN. To standardize for interlaboratory variation, the results for the various cytogenetic end points were trichotomized on the basis of the absolute value distribution within each laboratory as "low" (1-33 percentile), "medium" (34-66 percentile), or "high" (67-100 percentile). In the Nordic cohort, there was an elevated standardized incidence ratio (SMR) for all cancer among subjects with high CA frequency [1.53; 95% confidence interval (CI), 1.13-2.05] but not for those with medium or low CA frequency. In the Italian cohort, a SMR in cancer of 2.01 (95% CI, 1.35-2.89) was obtained for those with a high CA frequency level, whereas the SMRs for those with medium or low did not noticeably differ from unity. Cox's proportional hazards models gave no evidence that the effect of CAs on total cancer incidence/mortality was modified by gender, age at test, or time since test. No association was seen between the SCEs or the MN frequencies and subsequent cancer incidence/mortality. The present study further supports our previous observation on the cancer predictivity of the CA biomarker, which seems to be independent of age at test, gender, and time since test. The risk patterns were similar within each national cohort. This result suggests that the frequency of CAs in peripheral blood lymphocytes is a relevant biomarker for cancer risk in humans, reflecting either early biological effects of genotoxic carcinogens or individual cancer susceptibility.

Chromosomal aberrations in lymphocytes predict human cancer independently of exposure to carcinogens. European Study Group on Cytogenetic Biomarkers and Health.

An increased risk of cancer in healthy individuals with high levels of chromosomal aberrations (CAs) in peripheral blood lymphocytes has been described in recent epidemiological studies. This association did not appear to be modified by sex, age, country, or time since CA test, whereas the role played by exposure to carcinogens is still uncertain because of the requisite information concerning occupation and lifestyle was lacking. We evaluated in the present study whether CAs predicted cancer because they were the result of past exposure to carcinogens or because they were an intermediate end point in the pathway leading to disease. A nested case-control study was performed on 93 incident cancer cases and 62 deceased cancer cases coming from two prospective cohort studies performed in Nordic countries (Denmark, Finland, Norway, and Sweden) and Italy. For each case, four controls matched by country, sex, year of birth, and year of CA test were randomly selected. Occupational exposure and smoking habit were assessed by a collaborative group of occupational hygienists. Logistic regression models indicated a statistically significant increase in risk for subjects with a high level of CAs compared to those with a low level in the Nordic cohort (odds ratio, 2.35; 95% confidence interval, 1.31-4.23) and in the Italian cohort (odds ratio, 2.66; 95% confidence interval, 1.26-5.62). These estimates were not affected by the inclusion of occupational exposure level and smoking habit in the regression model. The risk for high versus low levels of CAs was similar in subjects heavily exposed to carcinogens and in those who had never, to their knowledge, been exposed to any major carcinogenic agent during their lifetime, supporting the idea that chromosome damage itself is involved in the pathway to cancer. The results have important ramifications for the understanding of the role played by sporadic chromosome damage for the origin of neoplasia-associated CAs.

Genotoxic damage in mine workers exposed to diesel exhaust, and the effects of glutathione transferase genotypes.

This study was performed in an Estonian shale-oil mine with the purpose to develop and apply a number of biomarkers for occupational diesel-exhaust exposure monitoring. Increased breathing-zone exposures to exhaust from operators of diesel-powered trucks in the mine was confirmed in the environmental monitoring part of the study, showing a 7.5-fold higher exposure to particle-associated 1-nitropyrene (1-NP) in 50 underground workers compared with 42 surface workers [P.T.J. Scheepers, D. Coggon, L.E. Knudsen, R. Anzion, H. Autrup, S. Bogovski, R.P. Bos, D. Dahmann, P. Farmer, E.A. Martin, V. Micka, V. Muzyka, H.-G. Neumann, J. Poole, A. Schmidt-Ott, F. Seiler, J. Volf, I. Zwirner-Baier, Biomarkers for occupational diesel exhaust exposure monitoring (BIOMODEM)-a study in underground mining, Toxicol. Lett. 134 (2002) 305-317; P.T.J. Scheepers, V. Micka, V. Muzyka, R. Anzion, D. Dahmann, J. Poole, R.P. Bos, Exposure to dust and particle-associated 1-nitropyrene of drivers of diesel-powered equipment in underground mining, Ann. Occp. Hyg. 47 (2003) 379-388]. Analysis of DNA damage by the Comet assay on frozen blood samples was performed on the total study group and showed significantly higher levels (p=0.003) in underground workers (smokers) driving diesel-powered excavation machines (median 155 on a scale from 0 to 400, among 47 persons), compared with surface workers who smoked (median of 90, among 46 persons). The level of DNA damage in underground smokers was significantly higher (p=0.04) than in non-smokers. Samples from 2 of the 3 sampling weeks had significantly lower DNA damage compared with the third week, probably due to timely processing and freezing. These samples also showed significant differences (p<0.001) between underground workers (median 145, among 41 persons) and surface workers (median 60, among 30 persons). An HPLC method was developed for the analysis of (32)P-postlabelled 1-NP-DNA-adducts, and was applied to a sub-sample of 20 workers. No significant differences between surface and underground workers were found in this sub-sample with respect to the minor, unidentified adducts that had similar chromatographic properties to 1-NP adducts, and smoking did not have any effect on adduct levels. No significant effects of the genotypes of GSTM1, GSTP1 and GSTT1 on DNA-adducts and on DNA damage as measured by the Comet assay were found in the total study group. The study confirms an increased level of DNA damage in workers exposed to exhaust from truck-driving in the mine. However, the results of the environmental and biological monitoring of 1-NP did not correlate, suggesting that inhalation exposure to diesel exhaust is not reflected by an increase in 1-NP-DNA-adduct levels and/or that factors other than occupational exposure to diesel exhaust are primary determinants of these DNA-adduct levels.

Towards an alternative testing strategy for nanomaterials used in nanomedicine: lessons from NanoTEST.

In spite of recent advances in describing the health outcomes of exposure to nanoparticles (NPs), it still remains unclear how exactly NPs interact with their cellular targets. Size, surface, mass, geometry, and composition may all play a beneficial role as well as causing toxicity. Concerns of scientists, politicians and the public about potential health hazards associated with NPs need to be answered. With the variety of exposure routes available, there is potential for NPs to reach every organ in the body but we know little about the impact this might have. The main objective of the FP7 NanoTEST project ( www.nanotest-fp7.eu ) was a better understanding of mechanisms of interactions of NPs employed in nanomedicine with cells, tissues and organs and to address critical issues relating to toxicity testing especially with respect to alternatives to tests on animals. Here we describe an approach towards alternative testing strategies for hazard and risk assessment of nanomaterials, highlighting the adaptation of standard methods demanded by the special physicochemical features of nanomaterials and bioavailability studies. The work has assessed a broad range of toxicity tests, cell models and NP types and concentrations taking into account the inherent impact of NP properties and the effects of changes in experimental conditions using well-characterized NPs. The results of the studies have been used to generate recommendations for a suitable and robust testing strategy which can be applied to new medical NPs as they are developed.

The comet assay as a rapid test in biomonitoring occupational exposure to DNA-damaging agents and effect of confounding factors.

Within the last decade, the comet assay has been used with increasing popularity to investigate the level of DNA damage in terms of strand breaks and alkaline labile sites in biomonitoring studies. The assay is easily performed on WBCs and has been included in a wide range of biomonitoring studies of occupational exposures encompassing styrene, vinyl chloride, 1,3-butadiene, pesticides, hair dyes, antineoplastic agents, organic solvents, sewage and waste materials, wood dust, and ionizing radiation. Eleven of the occupational studies were positive, whereas seven were negative. Notably, the negative studies appeared to have less power than the positive studies. Also, there were poor dose-response relationships in many of the biomonitoring studies. Many factors have been reported to produce effects by the comet assay, e.g., age, air pollution exposure, diet, exercise, gender, infection, residential radon exposure, smoking, and season. Until now, the use of the comet assay has been hampered by the uncertainty of the influence of confounding factors. We argue that none of the confounding factors are unequivocally positive in the majority of the studies. We recommend that age, gender, and smoking status be used as criteria for the selection of populations and that data on exercise, diet, and recent infections be registered before blood sampling. Samples from exposed and unexposed populations should be collected at the same time to avoid seasonal variation. In general, the comet assay is considered a suitable and fast test for DNA-damaging potential in biomonitoring studies.

Chromosomal aberrations in humans induced by urban air pollution: influence of DNA repair and polymorphisms of glutathione S-transferase M1 and N-acetyltransferase 2.

We have studied the influence of individual susceptibility factors on the genotoxic effects of urban air pollution in 106 nonsmoking bus drivers and 101 postal workers in the Copenhagen metropolitan area. We used the frequency of chromosomal aberrations in peripheral blood lymphocytes as a biomarker of genotoxic damage and dimethylsulfate-induced unscheduled DNA synthesis in mononuclear WBCs, the glutathione S-transferase M1 (GSTM1) genotype, and the N-acetyltransferase 2 (NAT2) genotype as biomarkers of susceptibility. The bus drivers, who had previously been observed to have elevated levels of aromatic DNA adducts in their peripheral mononuclear cells, showed a significantly higher frequency of cells with chromosomal aberrations as compared with the postal workers. In the bus drivers, unscheduled DNA synthesis correlated negatively with the number of cells with gaps, indicating a protective effect of DNA repair toward chromosome damage. Bus drivers with the GSTM1 null and slow acetylator NAT2 genotype had an increased frequency of cells with chromosomal aberrations. NAT2 slow acetylators also showed elevated chromosomal aberration counts among the postal workers. Our results suggest that long-term exposure to urban air pollution (with traffic as the main contributor) induces chromosome damage in human somatic cells. Low DNA repair capacity and GSTM1 and NAT2 variants associated with reduced detoxification ability increase susceptibility to such damage. The effect of the GSTM1 genotype, which was observed only in the bus drivers, appears to be associated with air pollution, whereas the NAT2 genotype effect, which affected all subjects, may influence the individual response to some other common exposure or the baseline level of chromosomal aberrations.

Biomarkers for exposure to ambient air pollution--comparison of carcinogen-DNA adduct levels with other exposure markers and markers for oxidative stress.

Human exposure to genotoxic compounds present in ambient air has been studied using selected biomarkers in nonsmoking Danish bus drivers and postal workers. A large interindividual variation in biomarker levels was observed. Significantly higher levels of bulky carcinogen-DNA adducts (75.42 adducts/10(8) nucleotides) and of 2-amino-apidic semialdehyde (AAS) in plasma proteins (56.7 pmol/mg protein) were observed in bus drivers working in the central part of Copenhagen, Denmark. In contrast, significantly higher levels of AAS in hemoglobin (55.8 pmol/mg protein), malondialdehyde in plasma (0. 96 nmol/ml plasma), and polycyclic aromatic hydrocarbon (PAH)-albumin adduct (3.38 fmol/ microg albumin) were observed in the suburban group. The biomarker levels in postal workers were similar to the levels in suburban bus drivers. In the combined group of bus drivers and postal workers, negative correlations were observed between bulky carcinogen-DNA adduct and PAH-albumin levels (p = 0.005), and between DNA adduct and [gamma]-glutamyl semialdehyde (GGS) in hemoglobin (p = 0.11). Highly significant correlations were found between PAH-albumin adducts and AAS in plasma (p = 0.001) and GGS in hemoglobin (p = 0.001). Significant correlations were also observed between urinary 8-oxo-7, 8-dihydro-2'-deoxyguanosine and AAS in plasma (p = 0.001) and PAH-albumin adducts (p = 0.002). The influence of the glutatione S-transferase (GST) M1 deletion on the correlation between the biomarkers was studied in the combined group. A significant negative correlation was only observed between bulky carcinogen-DNA adducts and PAH-albumin adducts (p = 0.02) and between DNA adduct and urinary mutagenic activity (p = 0.02) in the GSTM1 null group, but not in the workers who were homozygotes or heterozygotes for GSTM1. Our results indicate that some of the selected biomarkers can be used to distinguish between high and low exposure to environmental genotoxins.

Reference interval and subject variation in excretion of urinary metabolites of nicotine from non-smoking healthy subjects in Denmark.

BACKGROUND: Passive smoking has been found to be a respiratory health hazard in humans. The present study describes the calculation of a reference interval for urinary nicotine metabolites calculated as cotinine equivalents on the basis of 72 non-smokers exposed to tobacco smoke less than 25% of the day. METHODS: Twenty subjects (passive smokers) exposed to tobacco smoke more than 25% of the day (subjectively assessed) and 32 smokers were used to validate the estimated reference interval. Urine samples were collected three times during the day approximately at 06.30, 17.00 and 22.45 h. RESULTS: Within-subject variation was found to be 89.4, 72.6, and 79.2% and between-subject variation was found to be 64.5, 64.2, and 36.1%. No gender difference could be demonstrated. In general all subjects showed increased concentrations in the afternoon and evening samples compared to the morning samples. Parametric reference interval for excretion of nicotine metabolites in urine from non-smokers was established according to International Union of Pure and Applied Chemistry (IUPAC) and International Federation for Clinical Chemistry (IFCC) for use of risk assessment of exposure to tobacco smoke. The reference interval for urinary cotinine was estimated to be 1.1-90.0 micromol/mol creatinine in morning samples from non-smokers. An intercomparison between the radioimmunoassay (RIA) method used for determination of nicotine metabolites and a gas chromatography-mass spectrometry (GC-MS) method for determination of cotinine was carried out on 27 samples from non-smokers and smokers. Results obtained from the RIA method showed 2.84 [confidence interval (CI): 2.50; 3.18] times higher results compared to the GC-MS method. A linear correlation between the two methods was demonstrated (rho=0.96). CONCLUSION: The RIA method is rapid and adequate for clinical use in the assessment of exposure to tobacco smoke, i.e. ratio between CV(a)/CV(ti) was<0.50.

Oxidative stress associated with exercise, psychological stress and life-style factors.

Oxidative stress is a cellular or physiological condition of elevated concentrations of reactive oxygen species that cause molecular damage to vital structures and functions. Several factors influence the susceptibility to oxidative stress by affecting the antioxidant status or free oxygen radical generation. Here, we review the effect of alcohol, air pollution, cigarette smoke, diet, exercise, non-ionizing radiation (UV and microwaves) and psychological stress on the development of oxidative stress. Regular exercise and carbohydrate-rich diets seem to increase the resistance against oxidative stress. Air pollution, alcohol, cigarette smoke, non-ionizing radiation and psychological stress seem to increase oxidative stress. Alcohol in lower doses may act as an antioxidant on low density lipoproteins and thereby have an anti-atherosclerotic property.

BIOMarkers for occupational diesel exhaust exposure monitoring (BIOMODEM)--a study in underground mining.

Methods for the assessment of exposures to diesel exhaust were evaluated, including various biomarkers of internal exposure and early biological effects. The impact of possible biomarkers of susceptibility was also explored. Underground workers (drivers of diesel-powered excavators) at an oil shale mine in Estonia were compared with surface workers. Personal exposures to particle-associated 1-nitropyrene (NP) were some eight times higher underground than on the surface. Underground miners were also occupationally exposed to benzene and polycyclic aromatic hydrocarbons, as indicated by excretion of urinary metabolites of benzene and pyrene. In addition, increased O(6)-alkylguanine DNA adducts were detected in the white blood cells of underground workers, suggesting higher exposure to nitroso-compounds. However, no differences between underground and surface workers were observed in the levels of other bulky DNA adducts determined by 32P-postlabelling, or in DNA damage. The study indicated that smoking, diet and residential indoor air pollution are important non-occupational factors to consider when interpreting biomonitoring results.