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The respiratory tract is the main target organ of the inhaled hexavalent chromium (Cr-VI) and nickel (Ni) contained in stainless steel (SS) welding fumes (WFs). The aim of this study was to investigate the Cr and Ni content of the exhaled breath condensate (EBC) of SS tungsten inert gas (TIG) welders, and relate their concentrations with oxidative stress and inflammatory biomarkers. EBC and urine from 100 SS TIG welders were collected pre-(T 0 ) and post-shift (T 1 ) on a Friday, and pre-shift (T 2 ) on the following Monday morning. Both EBC and urinary Cr concentrations were higher at T 1 (0.08 μg/L and 0.71 μg/g creatinine) and T 0 (0.06 μg/L and 0.74 μg/g creatinine) than at T 2 (below the limit of detection [LOD] and 0.59 μg/g creatinine), and EBC Ni concentrations generally remained 2 O 2 ) concentration increased from 0.18 μM at T 0 to 0.25 μM at T 1 , but had decreased to 0.16 μM by T 2 . EBC malondialdehyde (MDA) concentrations were higher at T 0 (2.79 nM) and T 1 (2.98 nM) than at T 2 (2.43 nM), and EBC 4-hydroxy-nonenal (HNE) concentrations were higher at T 0 (0.53 nM) than at T 2 (0.51 nM). These findings confirm that, unlike Ni-EBC, Cr-EBC is a reliable biomarker of exposure even at very low environmental concentrations. However, given the weak relationship between the biomarkers and effects of exposure, we speculate that other substances generated during SS TIG welding also play a role in generating lung oxidative stress., (Copyright © 2018 Elsevier B.V. All rights reserved.)

This study investigated nucleic acid oxidation associated with exposure to benzene at low levels in 239 workers recruited among traffic policemen, taxi drivers and gasoline pump attendants of the city of Parma (Italy). Biomarkers of exposure, namely urinary t,t-muconic acid (t,t-MA) and S-phenylmercapturic acid (S-PMA), urinary cotinine, and urinary biomarkers of nucleic acid oxidation, namely 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo), 8-oxo-7,8-dihydroguanosine (8-oxoGuo) and 8-oxo-7,8-dihydroguanine (8-oxoGua) were determined by liquid chromatography-tandem mass spectrometry. Relevant polymorphisms of NAD(P)H:quinone oxidoreductase (NQO1), glutathione S-transferases M1-1 (GSTM1), T1-1 (GSTT1), and A1 (GSTA1) were characterized by polymerase chain reaction-based methods in a subgroup of subjects. Biomarkers of nucleic acid oxidation were correlated with each other (r> or =0.32, p<0.0001) and with exposure biomarkers (r> or =0.28, p<0.0001). Multiple linear regression models including age, sex and smoking habits as independent variables demonstrated that benzene exposure is associated with oxidation damage to nucleic acid, particularly to RNA (p<0.0001) and is modulated by the NQO1 polymorphism. The study confirmed a significant modulating effect of GSTM1 (p=0.010), GSTT1 (p=0.023) and GSTA1 (p=0.048) polymorphisms on S-PMA excretion, with a significant interaction between GSTM1 and both GSTT1 and GSTA1 (p=0.006 and p=0.037, respectively)., (2010 Elsevier Ireland Ltd. All rights reserved.)

This study investigated nucleic acid oxidation associated with styrene exposure, mRNA expression levels of hOGG1 gene and the role of the genetic polymorphism Ser326Cys of human 8-oxoguanine DNA N-glycosylase 1 (hOGG1) in 60 styrene-exposed workers and 50 unexposed clerks. Biomarkers of exposure (styrene in blood, mandelic and phenylglyoxylic acids and 4-vinylphenol in urine) and urinary biomarkers of nucleic acid oxidation, namely 8-oxo-7,8-dihydro-2'-deoxyguanosine (U-8-oxodGuo), 8-oxo-7,8-dihydroguanosine (U-8-oxoGuo) and 8-oxo-7,8-dihydroguanine (U-8-oxoGua) were determined by liquid chromatography-tandem mass spectrometry. The levels of 8-oxodGuo adduct and 2'-deoxyguanosine (dGuo) were measured by HPLC in DNA from white blood cells (WBC). Genomic DNA and RNA from blood samples were used to characterize the Ser326Cys polymorphism and the mRNA expression levels of the hOGG1 gene, respectively, by PCR-based methods. Exposed workers showed lower values of 8-oxodGuo/10(5) dGuo ratio in WBC-DNA but higher concentrations of U-8-oxoGuo compared to controls (p=0.002 and p=0.008, respectively, t-test for independent samples). In the whole group, all urinary biomarkers of nucleic acid oxidation correlated with both the sum of mandelic and phenylglyoxylic acids (rho>0.33, p<0.0001) and 4-vinylphenol (rho>0.29, p<0.001), whereas 8-oxodGuo/10(5) dGuo in WBC showed a negative correlation with exposure parameters (rho<-0.24, p<0.02). Subjects bearing the hOGG1 Ser/Ser genotype showed lower values of 8-oxodGuo/10(5) dGuo in WBC than those with at least one variant Cys allele (0.34+/-0.16 vs 0.45+/-0.21, p=0.008). In the subgroup of hOGG1 Ser/Ser subjects, laminators showed lower levels of WBC 8-oxodGuo/10(5) dGuo ratio and significantly higher concentrations of U-8-oxoGua than controls (p=0.07 and p=0.01, respectively, t-test for independent samples). Interestingly, workers showed higher levels of hOGG1 expression compared to controls (p<0.0005). Styrene exposure seems to be associated with oxidation damage to nucleic acids, particularly to RNA and with an induction of the BER system.

An integrated approach based on ambient and biological monitoring, the latter including both biomarkers of exposure and susceptibility, was applied to characterize benzene exposure in a group of 37 taxi drivers of the city of Parma (Italy). Airborne benzene concentrations were assessed by 24 h personal sampling and work-shift sampling inside the taxicab using passive samplers (Radiello). Benzene metabolites, trans,trans-muconic acid (t,t-MA) and S-phenylmercapturic acid (S-PMA), and urinary cotinine as biomarker of smoking habits were measured by isotopic dilution liquid chromatography tandem mass spectrometry in both pre-shift (PS) and end-of-shift (EOS) samples. Urinary benzene (U-B) levels were determined by solid-phase microextraction gas chromatography-mass spectrometry in EOS samples. Relevant polymorphisms of microsomal epoxide hydrolase, NAD(P)H:quinone oxidoreductase, glutathione S-transferases M1-1 (GSTM1), T1-1, and A1 were characterized by PCR-based methods. Mean airborne benzene concentration was 5.85 +/- 1.65 microg/m3, as assessed by 24 h personal sampling integrating for work-shift, indoor or general environment activities. Significantly, higher benzene concentrations were detected in the taxicab during the work-shift (7.71 +/- 1.95 microg/m3, p < 0.005). Smokers eliminated significantly higher concentrations of U-B and S-PMA than non-smokers in EOS samples [geometric mean (geometric S.D.): 2.58 (4.23) versus 0.44 (1.79) microg/l for U-B; 3.79 (1.50) versus 2.14 (1.87) microg/gcreat. for S-PMA, p < 0.002]. Within smokers, S-PMA concentrations significantly increased at the end of the work-shift compared to pre-shift values (p < 0.05). t,t-MA showed a similar behaviour, although differences were not significant. In the narrow range examined, no correlation was observed between air benzene concentration and urinary biomarkers. All benzene biomarkers but EOS t,t-MA were correlated with U-cotinine (p < 0.05). GSTM1 polymorphism significantly modulated S-PMA excretion, as subjects bearing the GSTM1pos genotype [3.61 (1.15) microg/gcreat.] excreted significantly higher S-PMA concentrations than GSTM1null subjects [2.19 (1.18) microg/gcreat., p < 0.05].

Two workers were accidentally exposed to unusually high styrene concentrations (>1000 ppm) for about 30 min. In addition to the main styrene metabolites, mandelic acid (MA) and phenylglyoxylic acid (PGA), other minor metabolites, including specific mercapturic acids, (R,R)- and (S,R)-N-acetyl-S-(1-phenyl-2-hydroxyethyl)-L-cysteine [(R,R)-M1 and (S,R)-M1] and (R,R)- and (S,R)-N-acetyl-S-(2-phenyl-2-hydroxyethyl)-L-cysteine [(R,R)-M2 and (S,R)-M2], 4-vinylphenol-glucuronide and -sulfate, and phenylglycine, were determined by Liquid Chromatography Electrospray Tandem Mass Spectrometry (LC-ESI-MS/MS) in urine samples collected 12, 24, 36, 48, 75 and 99 h after the episode. The genotypes of microsomal epoxide hydrolase, glutathione-S-transferases M1-1 (GSTM1), T1-1 (GSTT1) and P1-1 (GSTP1) were characterized by PCR-based methods. The two subjects showed similar peak levels of MA and PGA, as well as 4-vinylphenol conjugates, whereas mercapturic acids were five times higher in the subject bearing the GSTM1pos than in the GSTM1null subject. Also, relative proportions of diasteroisomers of mercapturic acids were influenced by the GSTM1 polymorphism.

This study was aimed at evaluating whether controlled short-term exposure to ozone (O(3)) induces changes in biomarkers of lung inflammation and oxidative stress in exhaled breath condensate (EBC) and blood of healthy subjects. Twenty-two volunteers were exposed to 0.1 ppm of O(3) for 2 h while performing moderate intermittent exercise. EBC and blood were collected before, immediately after and 18 h after exposure. Changes in biomarkers were measured both in EBC and blood, without significant alterations of lung function tests. Changes in EBC, but not in blood, were mainly accounted for by a subgroup of 'susceptible' individuals bearing the wild genotype for NAD(P)H:quinone oxidoreductase (NQO1) and the null genotype for glutathione-S-transferase M1 (GSTM1). Thus, a single 2-h exposure to 0.1 ppm of O(3) induces changes in biomarkers of inflammation and oxidative stress. Polymorphic NQO1 and GSTM1 act as modifier of the lung response to O(3).

A quasi-experimental field study was carried out in 24 volunteers with the aim of: (i) assessing personal exposure to aromatic hydrocarbons polluting urban areas; and (ii) exploring the role of polymorphic enzymes relevant to the biotransformation of benzene in the inter-individual variability of biomarkers. Each subject covered by bicycle: (i) inner city routes with often jammed traffic; and (ii) open rural routes. Time-weighted average airborne concentrations of benzene, toluene, ethylbenzene and xylenes (BTEX) were determined during 2-h runs. BTEX were determined by solid-phase micro-extraction (SPME) followed by gas chromatography coupled with mass spectrometry (GC-MS) in blood and spot urine samples collected just before and immediately after the runs. Urinary t,t-muconic acid was measured by high performance liquid chromatography (HPLC)-UV. Genotypes of epoxide hydrolase (EH) and glutathione-S-transferase class mu-1 (GSTM1) were also characterised. As compared to pre-run values, benzene and toluene in blood, and toluene and xylenes in urine significantly increased after urban runs. Urinary t,t-muconic acid was significantly higher in post-run samples after both urban (P < 0.001) and rural runs (P < 0.05). Despite a narrow range of exposure levels, a significant relationship was observed between airborne benzene and post-run t,t-muconic acid (r2 = 0.349, P < 0.00). When subgroups were distinguished according to EH and GSTM, subjects bearing both the EH wild type and GSTM 'null' genotype showed significant exposure-related changes in t,t-muconic acid excretion. Even at very low exposure levels, a 2-h bike run in a polluted urban environment may give rise to measurable changes in biomarkers of internal dose of selected aromatic hydrocarbons. Genetically-based metabolic differences may account for part of the inter-individual variability of biomarkers of exposure.