Ning Tang

Evaluation of urinary metabolites of 1-nitropyrene as biomarkers for exposure to diesel exhaust in taxi drivers of Shenyang, China.

Diesel exhaust (DE) is a significant contributor to the toxicity associated with particulate matter (PM). 1-Nitropyrene (1-NP) has been used as a molecular marker for DE, and the urinary metabolites of 1-NP have been proposed as biomarkers for exposure to DE. In this study, several urinary 1-NP metabolites were evaluated for their utility as markers of short-term exposures to DE. The study population was a cohort of 24 taxi drivers from Shenyang, China, who submitted urine samples collected before, after, and the next morning following their workshifts. The urinary metabolites studied were isomers of hydroxy-1-nitropyrene (3-, 6-, 8- OHNPs) and hydroxy-N-acetyl-1-aminopyrene (3-,6-, 8-OHNAAPs). Exposure to DE was estimated based on exposure to 1-NP in air samples collected during and after the drivers workshift; 6- and 8-OHNP, and 8-OHNAAP were consistently detected in the drivers’ urine. Concentrations of the metabolites in the taxi drivers’ urine were greater than metabolite levels previously reported in non-occupationally exposed subjects; however no associations were observed between subject-specific exposures to 1-NP and urinary metabolites measured at the end of the workshift or in the next morning void. Significant autocorrelation was observed in metabolite levels in successive urine samples, from which half-lives for urinary elimination of ∼10–12u2009h were estimated. These observations suggest that, in an occupational setting, urinary 1-NP metabolites may be more suitable as markers of ongoing exposure (timescales of several days) rather than indicators of acute exposure associated with single workshifts.

Analysis of 8-hydroxy-2'-deoxyguanosine in human urine using hydrophilic interaction chromatography with tandem mass spectrometry.

Urinary 8-hydroxy-2-deoxyguanosine (8-OHdG) is a widely used noninvasive biomarker of oxidative stress. A selective, sensitive and rapid method for determining 8-OHdG in human urine was developed using hydrophilic interaction chromatography-tandem mass spectrometry (HILIC-MS/MS) with electrospray ionization. 8-OHdG and isotopically labeled 8-OHdG (internal standard) were separated on a HILIC column with a mobile phase of 10 mM ammonium acetate: acetonitrile (1:9, v/v) within 10 min and detected by using a positive electrospray ionization interface under the selected reaction monitoring mode. The detection limits of 8-OHdG (corresponding to a signal-to-noise ratio of 3) for the HILIC-MS/MS system and the conventional method using a reversed-phase column with MS/MS were 1.0 and 26.0 fmol/injection, respectively. The proposed method makes it possible to monitor the basal level of urinary 8-OHdG from non-exposed healthy subjects and can be used for large-scale human studies.

Gene Expression Changes of Phases I and II Metabolizing Enzymes Induced by PAH Derivatives

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants, and generate various types of PAH derivatives, such as nitrated PAHs, hydroxylated PAHs, and PAH quinones through chemical reactions in the atmosphere. PAHs are well known to activate the aryl hydrocarbon receptor (AhR), followed by the induction of metabolizing enzymes mainly in the liver, while biological responses to PAH derivatives are not understood well. In this study, we investigated the induction patterns of gene expression of CYP1 family and Phase II metabolizing enzymes in rat H4IIE cells exposed to PAH quinones and their parent PAHs for 24 h. Dibenz[a,h]anthracene and benzo[a]pyrene dramatically induced mRNA expression of CYP1 family, such as cytochrome P450 (Cyp) 1a1, Cyp1a2, and Cyp1b1, and PAH quinones, especially 1,4-chrysenequinone, possess a high potential to induce CYP1 family. As for Phase II enzymes, PAHs induced NAD(P)H: quinone oxidoreductase 1 (Nqo1) and UDP-glucuronosyltransferase (Ugt)1a6, and their induction potencies by PAHs were similar to those of CYP1 family. On the other hand, expression of sulfotransferase (Sult)1a1, heme oxygenase-1 (Hmox1), and Ugt2b1 were augmented mainly by PAH derivatives. Finally, we examined gene expression changes of metabolizing enzymes by the airborne particles. Their organic extracts significantly up-regulated the expression of Cyp1a1, Cyp1a2, Cyp1b1, Ugt1a6, and Nqo1, but not Hmox1, Ugt2b1, and Sult1a1. These results suggest that PAHs mainly induce the expression of genes encoding CYP1 family while PAH derivatives, especially quinones, induce the expression of genes encoding both CYP1 family and Phase II enzymes. Furthermore, our results show the organic chemicals which adsorb on the airborne particles exert biological effects in the similar manner of PAHs, suggesting the involvement of mainly AhR activation.

Personal and Atmospheric Concentrations of Ozone in Southeastern Hyogo Prefecture, Japan

Twenty-one data sets composed of readings collected by atmospheric ozone monitors worn by individuals on their clothing and installed outside their home or office were collected using Ogawa passive ozone samplers in southeastern Hyogo prefecture, Japan from September 12 to 13, 2011. The concentrations of personal and outdoor ozone ranged from not detectable to 23.2 ppb and from 4.7 to 38.3 ppb, respectively. The mean concentration of personal exposure to ozone was 3.7 ppb and was significantly lower than that of outdoor ozone (18.5 ppb). This suggests that the concentrations of outdoor ozone affect personal ozone exposure. However, in this study, we found no correlation between the concentrations of personal ozone and the total time spent outdoors or the time of day the individual was outside. In contrast, the mean concentrations of outdoor ozone were similar to those of ozone measured at the 12 nearest Ambient Monitoring Stations (AMSs). However, when the AMS was situated near a main road, the regional ozone levels were underestimated.