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Archives of Toxicology (v.85, #1)
The Human Bitumen Study: executive summary by Monika Raulf-Heimsoth; Beate Pesch; Reinhold Rühl; Thomas Brüning (pp. 3-9).
Bitumen has attracted attention from the scientific community and regulating agencies. The debate on health effects of exposure to vapours and aerosols of bitumen during the hot application of bitumen ranges from respiratory and neurological effects to carcinogenicity. In 2000, the German Hazardous Substances Committee (AGS), in collaboration with the German Bitumen Forum, initiated the examination of a group of mastic asphalt workers and a same number of construction workers without exposure bitumen using a cross-shift design. The study was then extended to the Human Bitumen Study, and the recruitment was finished in 2008 after examination of 500 workers on 80 construction sites. Three hundred and twenty workers exposed to vapours and aerosols of bitumen at high processing temperatures and 118 workers at outdoor construction sites were included. In the Human Bitumen Study external exposure to vapours and aerosols of bitumen, internal exposure to PAH by analysing urinary 1-hydroxypyrene, the sum of hydroxyphenanthrenes and the sum of 1- and 2-hydroxynaphthalenes, irritative effects in the upper and lower airways and genotoxic effects in blood cells were investigated. The study turned out to be one of the largest investigations of workers exposed to vapours and aerosols of bitumen under current exposure conditions. The present paper summarizes its background and main topics.
Keywords: Bitumen; Exposure; Genotoxicity; Irritation; Human exposure
The role of metabolites and metabolomics in clinically applicable biomarkers of disease by Mamas Mamas; Warwick B. Dunn; Ludwig Neyses; Royston Goodacre (pp. 5-17).
Metabolomics allows the simultaneous and relative quantification of thousands of different metabolites within a given sample using sensitive and specific methodologies such as gas or liquid chromatography coupled to mass spectrometry, typically in discovery phases of studies. Biomarkers are biological characteristics that are objectively measured and evaluated as indicators of normal biological processes, pathological processes or pharmacologic responses to a therapeutic intervention. Biomarkers are widely used in clinical practice for the diagnosis, assessment of severity and response to therapy in a number of clinical disease states. In human studies, metabolomics has been applied to define biomarkers related to prognosis or diagnosis of a disease or drug toxicity/efficacy and in doing so hopes to provide greater pathophysiological understanding of disease or therapeutic toxicity/efficacy. This review discusses the application of metabolomics in the discovery and subsequent application of biomarkers in the diagnosis and management of inborn errors of metabolism, cardiovascular disease and cancer. We critically appraise how novel biomarkers discovered through metabolomic analysis may be utilized in future clinical practice by addressing the following three fundamental questions: (1) Can the clinician measure them? (2) Do they add new information? (3) Do they help the clinician to manage patients? Although a number of novel biomarkers have been discovered through metabolomic studies of human diseases in the last decade, none have currently made the transition to routine use in clinical practice. Metabolites identified from these early studies will need to form the basis of larger, prospective, externally validated studies in clinical cohorts for their future use as biomarkers. At this stage, the absolute quantification of these biomarkers will need to be assessed epidemiologically, as will the ultimate deployment in the clinic via routine biochemistry, dip stick or similar rapid at- or near-patient care technologies.
Keywords: Metabolomics; Biomarkers; Systems biology
Air sampling and determination of vapours and aerosols of bitumen and polycyclic aromatic hydrocarbons in the Human Bitumen Study by Dietmar Breuer; Jens-Uwe Hahn; Dieter Höber; Christoph Emmel; Uwe Musanke; Reinhold Rühl; Anne Spickenheuer; Monika Raulf-Heimsoth; Rainer Bramer; Albrecht Seidel; Bernd Schilling; Evelyn Heinze; Benjamin Kendzia; Boleslaw Marczynski; Peter Welge; Jürgen Angerer; Thomas Brüning; Beate Pesch (pp. 11-20).
The chemical complexity of emissions from bitumen applications is a challenge in the assessment of exposure. Personal sampling of vapours and aerosols of bitumen was organized in 320 bitumen-exposed workers and 69 non-exposed construction workers during 2001–2008. Area sampling was conducted at 44 construction sites. Area and personal sampling of vapours and aerosols of bitumen showed similar concentrations between 5 and 10 mg/m3, while area sampling yielded higher concentrations above the former occupational exposure limit (OEL) of 10 mg/m3. The median concentration of personal bitumen exposure was 3.46 mg/m3 (inter-quartile range 1.80–5.90 mg/m3). Only few workers were exposed above the former OEL. The specificity of the method measuring C–H stretch vibration is limited. This accounts for a median background level of 0.20 mg/m³ in non-exposed workers which is likely due to ubiquitous aliphatic hydrocarbons. Further, area measurements of polycyclic aromatic hydrocarbons (PAHs) were taken at 25 construction sites. U.S. EPA PAHs were determined with GC/MS, with the result of a median concentration of 2.47 μg/m3 at 15 mastic asphalt worksites associated with vapours and aerosols of bitumen, with a Spearman correlation coefficient of 0.45 (95% CI −0.13 to 0.78). PAH exposure at mastic-asphalt works was higher than at reference worksites (median 0.21 μg/m3), but about one order of magnitude lower compared to coke-oven works. For a comparison of concentrations of vapours and aerosols of bitumen and PAHs in asphalt works, differences in sampling and analytical methods must to be taken into account.
Keywords: Air sampling; Asphalt; Bitumen; Exposure assessment; Polycyclic aromatic hydrocarbons
Perinatal cisplatin exposure induces cochlear apoptosis in newborn guinea pigs by Shuai Hao; Xuejun Jiang; Aihui Yan; Bo Yang (pp. 19-25).
The objective of this study was to evaluate the role of apoptosis in the development of the newborn cochlear structures and hearing loss caused by prenatal cis-diaminedichloroplatinum (cisplatin) exposure. Pregnant albino guinea pigs were intraperitoneally injected with 1.5 mg/kg body weight cisplatin once a day for seven consecutive days at gestational day (GD) 51 to GD 57. At postnatal day (PND) 14, pups were examined in the distortion product otoacoustic emission (DPOAE) task. The temporal bones were then removed and immunohistochemically stained for caspase 3, using the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling (TUNEL) method. Cisplatin used during pregnancy could induce hearing loss in newborn and cochlear hair cell apoptosis. In conclusion, apoptosis may play an important role in the development of hearing impairment, caused by perinatal cisplatin exposure.
Keywords: Cis-diaminedichloroplatinum (cisplatin); Perinatal exposure; Cochlear apoptosis; Caspase-3; Newborn
Levels and determinants of exposure to vapours and aerosols of bitumen by Anne Spickenheuer; Reinhold Rühl; Dieter Höber; Monika Raulf-Heimsoth; Boleslaw Marczynski; Peter Welge; Dietmar Breuer; Stefan Gabriel; Uwe Musanke; Peter Rode; Evelyn Heinze; Benjamin Kendzia; Rainer Bramer; Udo Knecht; Jens-Uwe Hahn; Thomas Brüning; Beate Pesch (pp. 21-28).
Bitumen (referred to as asphalt in the United States) is a widely used construction material, and emissions from hot bitumen applications have been a long-standing health concern. One objective of the Human Bitumen Study was to identify potential determinants of the exposure to bitumen. The study population analysed comprised 259 male mastic asphalt workers recruited between 2003 and 2008. Personal air sampling in the workers’ breathing zone was carried out during the shift to measure exposure to vapours and aerosols of bitumen. The majority of workers were engaged in building construction, where exposure levels were lower than in tunnels but higher than at road construction sites. At building construction sites, exposure levels were influenced by the room size, the processing temperature of the mastic asphalt and the job task. The results show that protective measures should include a reduction in the processing temperature.
Keywords: Asphalt; Bitumen; Exposure assessment; Mastic asphalt; Paving
Proteomic analysis of brain proteins of rats exposed to high fluoride and low iodine by Yaming Ge; Ruiyan Niu; Jianhai Zhang; Jundong Wang (pp. 27-33).
Epidemiological investigations reveal that high fluoride and low iodine have strong adverse effects on the intelligence quotient (IQ) of children. Studies also report that in some high fluoride areas, iodine deficiency also exists, especially in China. Here, with the proteomic techniques, we first report on the proteomic changes in brain proteins in offspring rats at postnatal day 20 exposed to high fluoride and/or low iodine. To investigate molecular mechanisms of central neural system injury induced by the above two elements, proteins were isolated and profiled by two-dimensional gel electrophoresis (2DE). By the analysis of Image-Master 2D Elite software, 71 protein spots in 2DE gels of treatment groups were gained and up- or down-regulated by two folds, and 5 proteins were regulated by five folds, with the comparison to the control group. The proteins changed by five folds were identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). The identified proteins are mainly related with cellular signaling, energy metabolism, and protein metabolism and provide a valuable clue to explore the mechanism underlining the neurotoxicity of high fluoride and low iodine. Moreover, these results could provide potential biomarkers for hazards caused by excessive fluoride and low iodine.
Keywords: Brain protein; Fluoride; Iodine deficiency; Two-dimensional electrophoresis; Mass spectrometry; Proteomic
Urinary metabolites of polycyclic aromatic hydrocarbons in workers exposed to vapours and aerosols of bitumen by Beate Pesch; Anne Spickenheuer; Benjamin Kendzia; Birgit Karin Schindler; Peter Welge; Boleslaw Marczynski; Hans-Peter Rihs; Monika Raulf-Heimsoth; Jürgen Angerer; Thomas Brüning (pp. 29-39).
Urinary hydroxylated metabolites of polycyclic aromatic hydrocarbons (PAH) were investigated as potential biomarkers of bitumen exposure in a cross-shift study in 317 exposed and 117 non-exposed workers. Personal measurements of the airborne concentration of vapours and aerosols of bitumen during a working shift were weakly associated with post-shift concentrations of 1-hydroxypyrene (1-OHP) and 1-, 2+9-, 3- and 4-hydroxyphenanthrenes (further referred to their sum as OHPHE), but not 1- and 2-hydroxynaphthalene (OHNA). Smoking showed a strong influence on the metabolite concentrations, in particular on OHNA. Pre-shift concentrations of 1-OHP and OHPHE did not differ between the study groups (P = 0.16 and P = 0.89, respectively). During shift, PAH metabolite concentrations increased in exposed workers and non-exposed smokers. Statistical modelling of post-shift concentrations revealed a small increase in 1-OHP by a factor of 1.02 per 1 mg/m3 bitumen (P = 0.02) and 1.04 for OHPHE (P < 0.001). A group difference was observed that was diminished in non-smokers. Exposed non-smokers had a median post-shift 1-OHP concentration of 0.42 μg/l, and non-smoking referents 0.13 μg/l. Although post-shift concentrations of 1-OHP and OHPHE were slightly higher than those in the general population, they were much lower than in coke-oven workers. The small content of PAHs in vapours and aerosols of bitumen, the increasing use of additives to asphalt mixtures, the strong impact of smoking and their weak association with airborne bitumen limit the use of PAH metabolites as specific biomarkers of bitumen exposure.
Keywords: Biomarker; Biomonitoring; Bitumen; Exposure; Polycyclic aromatic hydrocarbons
Antigen-subtracted 2-DE/MS strategy, a novel proteomic analysis platform by Peng Zhao; Lijuan Zhang; Weijian Zhong; Xianping Ying; He Huang; Biyun Yao; Zhun Yuan; Juanling Fu; Yuedan Wang; Zongcan Zhou (pp. 35-41).
In the present study, we developed a novel proteomic research strategy named antigen-subtracted 2-DE/MS strategy and applied it to comparative proteomic analysis of anti-benzo(a)pyrene-7,8-dihydrodiol-9,10-epoxide-transformed human bronchial epithelial cell line (16HBE-C) and its parental cell line (16HBE) G0/G1 cells. Following pre-purification by ammonium sulfate precipitation, rabbit antibodies against 16HBE G0/G1 cells were coupled with protein A/G PLUS-agarose under the maximal coupling rate of about 50%. The agarose-antibody complex was then used in immunoprecipitation known as antigen subtraction. When the mass ratio of antibody to the sample was 2.5–3:1, the subtraction rates for 16HBE and 16HBE-C G0/G1 cell proteins were 44 and 34%, respectively. Both subtracted and unsubtracted samples were then subjected to the 2-DE resolution. In 16HBE-subtracted 2-DE maps, 315 protein spots were subtracted and 49 new protein spots were detected, whereas in 16HBE-C-subtracted 2-DE maps, 287 protein spots were subtracted and 33 new protein spots were detected. Taken together, antigen subtraction results in 65 new protein spots being allowed to be detected, therefore, makes it possible to get more information of the samples. Finally, 4 protein spots only detected in 16HBE-C-subtracted 2-DE maps were analyzed by the Q-TOF MS/MS, and successfully identified as U6 snRNA-associated Sm-like protein LSm3, 60S acidic ribosomal protein P1, Peroxiredoxin-6 and 60S acidic ribosomal protein P2. These proteins are involved in carcinogenesis, oxidation stress and protein synthesis. In conclusion, the antigen-subtracted 2-DE/MS strategy could reduce the complexities of protein samples and therefore, improve the resolution for the sample analysis.
Keywords: Antigen subtraction; Two-dimensional gel electrophoresis; Q-TOF MS/MS; anti-Benzo(a)pyrene-7,8-dihydrodiol-9,10-epoxide (anti-BPDE); anti-BPDE-transformed cells
Irritative effects of vapours and aerosols of bitumen on the airways assessed by non-invasive methods by Monika Raulf-Heimsoth; Beate Pesch; Benjamin Kendzia; Anne Spickenheuer; Rainer Bramer; Boleslaw Marczynski; Rolf Merget; Thomas Brüning (pp. 41-52).
Irritative effects caused by vapours and aerosols of bitumen were assessed by non-invasive methods including spirometry, nasal lavage fluid (NALF) and induced sputum (IS) in a cross-shift study comparing 320 bitumen-exposed workers with 118 road construction workers as the reference group. Lung function parameters, forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were within normal ranges in both the reference and the bitumen-exposed groups pre- and post-shift with marginally lower values in smokers of both groups. During the shift, a slight decline in FEV1 and FVC was observed in the bitumen-exposed group independent of their smoking habits, whereas in the non-smoking reference group, the decline in FEV1 was not observed. No significant differences between bitumen-exposed workers and the reference group and no significant shift effect were observed on the upper airways using NALF analysis. The IS concentrations of interleukin (IL)-8, total protein and matrix metalloproteinase-9 were significantly higher in bitumen-exposed workers than in the reference group. However, the concentration of these three biomarkers in the IS samples, which are indicators of inflammatory effects on the lower airways of bitumen-exposed workers, was already higher in exposed workers before shift and did not show an increase during the shift. Therefore, the key finding of this aspect of the Human Bitumen Study is the detection of potentially (sub-) chronic irritative inflammatory effects in the lower airways of bitumen-exposed workers.
Keywords: Bitumen; Irritative effects; Cross-shift design; Nasal lavage; Induced sputum; Cellular and soluble biomarkers
Evaluation of the biological effects of (S)-dimethyl 2-(3-(phenyltellanyl) propanamido) succinate, a new telluroamino acid derivative of aspartic acid by Daiane Francine Meinerz; Jéssie H. Sudati; Danúbia B. dos Santos; Andressa Frediani; Eduardo E. Alberto; Josiane Allebrandt; Jeferson L. Franco; Nilda B. V. Barbosa; Michael Aschner; João Batista T. da Rocha (pp. 43-49).
(S)-dimethyl 2-(3-(phenyltellanyl) propanamido) succinate, a new telluroamino acid derivative, showed remarkable glutathione peroxidase (GPx)-like activity, attesting to its antioxidant potential. However, the stability and toxicity of this compound has not yet been investigated. The present study was designed to investigate the pharmacological/toxicological properties of this compound in vitro and in vivo. In vitro, this telluroamino acid derivative significantly blocked spontaneous and Fe(II)-induced TBARS formation in rat brain homogenates, demonstrating high antioxidant activity. In addition, it exhibited GPx-like and thiol oxidase activities. However, when subcutaneously administered to mice, (S)-dimethyl 2-(3-(phenyltellanyl) propanamido) succinate indicated genotoxic and mutagenic effect in adult male mice. Considering the differential effects of (S)-dimethyl 2-(3-(phenyltellanyl) propanamido) succinate in vitro and in vivo, additional experiments are needed to elucidate the mechanism(s) by which this compound displays its antioxidant/toxicological effects.
Keywords: Organotellurium derivative; Antioxidant; Genotoxicity; Mutagenicity
Preservation of uroplakins by 2-mercaptoethanesulfonate in cyclophosphamide-induced rat cystitis by Yoon Soo Kyung; Hee Yoon Park; Gilho Lee (pp. 51-57).
Cyclophosphamide (CP) causes extensive cystitis, which is ameliorated with concomitant treatment with mesna. We investigated the protective mechanisms of mesna in the expression of uroplakin (UP), a strong mucosal barrier against toxic materials, in CP-induced rat cystitis. A total of 54 SD female rats received a single intraperitoneal injection of 200 mg of CP/kg. Six CP-treated, 6 CP + mesna (120 mg/kg)-treated rats, and 6 negative controls were sequentially sacrificed at 12, 24, and 72 h post-CP injection. The bladders were harvested. The levels of UPIa, Ib, II, and III mRNA on real-time PCR, the UPII and III expressions on immunoblotting, and the UPII expression on immunolocalization study in the harvested bladder were maximally suppressed within 12–24 h, whereas partially or completely recovered at 24–72 h post-CP injection. In addition, the responses in UPs after a CP insult were heterogeneous (i.e., markedly suppressed in UPII and lesser destructive in UPIII). Even though the mesna-treated rats also showed transient and small reductions in the mRNA levels of all UPs, mesna clearly preserved the UP expressions of mRNA and protein in CP-induced urinary bladder mucosa. In conclusion, this study suggests that CP transiently reduces the expression of UPs and mesna protects the urinary bladder mucosa through the preservation of UPs protein.
Keywords: Cyclophosphamide; Mesna; Cystitis; Uroplakin; Rat
DNA adducts and strand breaks in workers exposed to vapours and aerosols of bitumen: associations between exposure and effect by Boleslaw Marczynski; Monika Raulf-Heimsoth; Anne Spickenheuer; Beate Pesch; Benjamin Kendzia; Thomas Mensing; Beate Engelhardt; Eun-Hyun Lee; Birgit K. Schindler; Evelyn Heinze; Peter Welge; Rainer Bramer; Jürgen Angerer; Dietmar Breuer; Heiko U. Käfferlein; Thomas Brüning (pp. 53-64).
To study the associations between exposure to vapours and aerosols of bitumen and genotoxic effects, a cross-sectional and cross-shift study was conducted in 320 exposed workers and 118 non-exposed construction workers. Ambient air measurements were carried out to assess external exposure to vapours and aerosols of bitumen. Hydroxylated metabolites of naphthalene, phenanthrene and pyrene were measured in urine, whereas (+)-anti-benzo[a]pyrene-7,8-diol-9,10-epoxide ((+)-anti-BPDE), 8-oxo-7,8-dihydro-2′-deoxyguanosine (8oxodGuo) and DNA strand breaks were determined in blood. Significantly higher levels of 8-oxodGuo adducts and DNA strand breaks were found in both pre- and post-shift blood samples of exposed workers compared to those of the referents. No differences between exposed workers and referents were observed for (+)-anti-BPDE. Moreover, no positive associations between DNA damage and magnitude of airborne exposure to vapours and aerosols of bitumen could be observed in our study. Additionally, no relevant association between the urinary metabolites of PAH and the DNA damage in blood was observed. Overall, our results indicate increased oxidative DNA damage in workers exposed to vapours and aerosols of bitumen compared to non-exposed referents at the group level. However, increased DNA strand breaks in bitumen workers were still within the range of those found in non-exposed and healthy persons as reported earlier. Due to the lack of an association between oxidative DNA damage and exposure levels at the workplaces under study, the observed increase in genotoxic effects in bitumen workers cannot be attributed to vapours and aerosols of bitumen.
Keywords: Bitumen; Genotoxicity; Biomarkers; Human biomonitoring
26-Week carcinogenicity study of di-isodecyl phthalate by dietary administration to CB6F1-rasH2 transgenic mice by Wan-Seob Cho; Jayoung Jeong; Mina Choi; Sue Nie Park; Beom Seok Han; Woo-Chan Son (pp. 59-66).
This study examined the carcinogenic potential of di-isodecyl phthalate (DIDP) in rasH2 mice. DIDP was administered to 15 rasH2 mice/gender/group at dietary levels of 0, 0.1, 0.33, or 1% and 15 wild-type mice/gender/group at dietary levels of 0 and 1% for 26 weeks. Non-neoplastic changes were observed in the liver (parenchymal inflammation, fatty changes, diffuse hepatocyte hypertrophy with eosinophilic granules and focal necrosis) and kidneys (tubular basophilia and tubular hyperplasia) after administration of DIDP in the rasH2 and wild-type mice. In the neoplastic lesions, there were a higher number of hepatocellular adenomas in the male rasH2 mice receiving 1% DIDP, compared with the findings in the liver of control rasH2 mice or wild-type mice. The incidence of hepatocellular adenomas in the 0.1, 0.33, and 1% DIDP exposed rasH2 mice was 7% (1/15), 7% (1/15), and 33% (5/15), respectively. This study adds a set of results for an additional test chemical for the performance of the rasH2 short-term transgenic model to the existing database of 3 compounds (WY-14643, DEHP, and clofibrate) tested in the ILSI/HESI ACT project.
Keywords: Di-isodecyl phthalate (DIDP); Peroxisome proliferator; rasH2 mice; 26-Week carcinogenicity study; Hepatocellular adenoma
Assessment of micronuclei in lymphocytes from workers exposed to vapours and aerosols of bitumen by Peter Welge; Boleslaw Marczynski; Monika Raulf-Heimsoth; Anne Spickenheuer; Benjamin Kendzia; Evelyn Heinze; Jürgen Angerer; Heiko U. Käfferlein; Beate Pesch; Thomas Brüning (pp. 65-71).
We investigated the micronucleus frequencies in peripheral blood lymphocytes of 225 mastic asphalt workers (age 17–62 years) and 69 non-bitumen-exposed road construction workers (age 18–64 years) in Germany before and after the working shift. Median shift exposure to vapours and aerosols of bitumen of exposed workers was 3.0 mg/m³. Micronuclei (MN) were determined with a standard method using cytochalasin B. Median MN frequency was 6.0 (interquartile range (IQR) 4.0–8.5) MN/1,000 binucleated lymphocytes (MN/1,000 BNC) in exposed workers and 6.0 (IQR 4.0–8.3) MN/1,000 BNC in non-exposed workers before shift. After shift, we observed 6.5 (IQR 4.4–9.3) MN/1,000 BNC in exposed workers and 6.5 (IQR 4.0–9.0) MN/1,000 BNC in non-exposed workers. Regression models were applied with the log-transformed MN frequency as the dependent variable in order to estimate the effects of exposure to vapours and aerosols of bitumen and of potential confounders. Age was the strongest predictor of MN formation in both exposed workers and referents. Our data suggest that MN formation was not associated with concentration of vapours and aerosols of bitumen during shift at the individual level. Although similar MN frequencies were observed in both groups, the modelling of factors potentially influencing MN frequency revealed a weak group difference in the post-shift model. We conclude that this small difference cannot be judged to be a relevant mutagenic effect of exposure to vapours and aerosols of bitumen, also with regard to the lack of adjustment for multiple testing and the lack of a group effect in the original data.
Keywords: Bitumen; Genotoxic effects; Micronucleus; Cross-shift design; Lymphocytes
The positive response of Ty1 retrotransposition test to carcinogens is due to increased levels of reactive oxygen species generated by the genotoxins by Martin Dimitrov; Pencho Venkov; Margarita Pesheva (pp. 67-74).
In previous laboratory and environmental studies, the Ty1 short-term test showed positive responses (i.e. induced mobility of the Ty1 retrotransposon) to carcinogenic genotoxins. Here, we provide evidence for a causal relationship between increased level of reactive oxygen species and induction the mobility of the Ty1 retrotransposon. Results obtained in concentration and time-dependent experiments after treatment, the tester cells with carcinogenic genotoxins [benzo(a)pyrene, benzo(a)anthracene, ethylmethanesulfonate, formamide], free bile acids (chenodeoxycholic, lithocholic acids) and metals (arsenic, hexavelant chromium, lead) showed a simultaneous increase in both cellular level of the superoxide anions and Ty1 retrotransposition rates. Treatment with the noncarcinogenic genotoxins [benzo(e)pyrene, benzo(b)anthracen, anthracene], conjugated bile acids (taurodeoxycholic, glycodeoxycholic acids) and metals (zinc, trivalent chromium) did not change significantly superoxide anions level and Ty1 retrotransposition rate. The induction by carcinogens of the Ty1 mobility seems to depend on the accumulation of superoxide anions, since the addition of the scavenger N-acetylcysteine resulted in loss of both increased amount of superoxide anions and induced Ty1 retrotransposition. Increased hydrogen peroxide levels are also involved in the induction of Ty1 retrotransposition rates in response to treatment with carcinogenic genotoxins, as evidenced by disruption of YAP1 gene in the tester cells. It is concluded that the carcinogen-induced high level of reactive oxygen species play a primary and key role in determination the selective response of Ty1 test to carcinogenic genotoxins.
Keywords: Ty1 retrotransposition; Carcinogens; Reactive oxygen species
Modulation of urinary polycyclic aromatic hydrocarbon metabolites by enzyme polymorphisms in workers of the German Human Bitumen Study by Hans-Peter Rihs; Anne Spickenheuer; Evelyn Heinze; Beate Pesch; Monika Raulf-Heimsoth; Jürgen Angerer; Thomas Brüning (pp. 73-79).
Data concerning the influence of sequence variants of metabolizing enzymes on the effect modulation of current exposure to vapors and aerosols of bitumen in humans are limited. To assess the influence of 18 single-nucleotide polymorphisms (SNP) in genes coding for enzymes involved in polycyclic aromatic hydrocarbon (PAH) and amine metabolism regarding their impact on urinary markers 1-hydroxpyrene (1-OHP) and the sum of 1-, 2+9-, 3-, 4-hydroxyphenanthrene (OHPHE). Based on personal ambient monitoring data for bitumen emissions, 218 German workers exposed to vapors and aerosols of bitumen during a shift and 96 German roadside construction workers without exposure to bitumen but with similar working tasks were studied. SNP determination based on DNA aliquots isolated from blood samples by real-time PCR or direct sequencing. The impact of sequence variants on the urinary levels of 1-OHP and sum of OHPHE was estimated with mixed linear models, adjusted for age, creatinine, exposure, smoking, SNP, and time of measurement. In the mixed linear model, an increasing metabolite level of OHPHE was only slightly modulated by the CC variant of the cytochrome P450 SNP CYP1A1 3801T>C (rs4646903; P = 0.051). In contrast, GSTM1 carriers showed a significant (P= 0.046) and double-mutated variants of three NAT2-specific SNP (NAT2*341CC, P = 0.06; NAT2*481TT, P = 0.06; NAT2*803GG, P = 0.042) displayed a decreasing influence on OHPHE levels. None of the SNP studied showed a significant effect on 1-OHP. The modulating SNP effects on OHPHE in the adjusted model were less pronounced when compared with the effects observed in a recent study with 170 workers occupationally exposed to PAH in German industries. This may be due to the much lower PAH exposure in the Human Bitumen Study.
Keywords: Bitumen; Hydroxyphenanthrenes; 1-hydroxypyrene; Polycyclic aromatic hydrocarbons; Real-time PCR; Single-nucleotide polymorphisms
Bitumen workers handling mastic versus rolled asphalt in a tunnel: assessment of exposure and biomarkers of irritation and genotoxicity by Monika Raulf-Heimsoth; Boleslaw Marczynski; Anne Spickenheuer; Beate Pesch; Peter Welge; Reinhold Rühl; Rainer Bramer; Benjamin Kendzia; Evelyn Heinze; Jürgen Angerer; Thomas Brüning (pp. 81-87).
Emission levels of vapours and aerosols of bitumen are different when processing rolled asphalt compared to mastic asphalt, with working temperatures up to 180 and 250°C, respectively. During the Human Bitumen Study, we examined six workers handling rolled asphalt and mastic asphalt in two consecutive weeks at the same construction site in a tunnel. In addition to the determination of exposure to bitumen and polycyclic aromatic hydrocarbons (PAH) during shift, we examined urinary PAH metabolites, irritative and genotoxic effects before and after shift. Median personal shift concentration of vapours and aerosols of bitumen was 1.8 (range 0.9–2.4) mg/m3 during the application of rolled asphalt and 7.9 (range 4.9–11.9) mg/m3 when mastic asphalt was applied. Area measurement of vapours and aerosols of bitumen revealed higher concentrations than the personal measurements for mastic asphalt (mastic asphalt: 34.9 mg/m3; rolled asphalt: 1.8 mg/m3). Processing mastic asphalt was associated also with higher PAH concentrations. Urinary 1-hydroxypyrene and the sum of 1-, 2+ 9-, 3- and 4-hydroxyphenanthrene increased slightly during shift without clear difference between mastic and rolled asphalt application. However, the post-shift urinary PAH-metabolite concentrations did not reflect the different PAH exposure during mastic and rolled asphalt application. Individual workers could be identified by their spirometry results indicating that these data reflect more chronic than acute effects. In most cases, an increase of 8-oxodGuo adducts was observed during shift that was independent of the asphalt application. 8-oxodGuo and (+)-anti-BPDE-DNA adducts were higher than in exposed workers of the Human Bitumen Study independent of the asphalt application. The DNA-strand breaks were considerably higher pre-shift and decreased during shift. In this study, mastic asphalt application led to significantly higher exposure to vapours and aerosols of bitumen, as well as to airborne PAH, compared to rolled asphalt application. Nevertheless, no differences in the excretion of urinary PAH metabolites, lung function impairment and genotoxic markers were detected. However, higher levels of genotoxicity markers on both examination days compared with the results of the Human Bitumen Study may indicate a possible influence of the specific tunnel setting.
Keywords: Bitumen; PAH metabolites; Spirometry; Genotoxic biomarkers; Rolled asphalt; Mastic asphalt