S-phenylmercapturic Acid Research Articles

Influence of genetic polymorphism on t,t-MA/S-PMA ratio in 301 benzene exposed subjects

This study investigated the effect of polymorphic genes GSTT1, GSTM1, GSTA1, EHPX1, NQO1, CYP2E1, CYP1A and MPO on the urinary concentrations and ratio (R) of the benzene metabolites trans,trans-muconic acid (t,t-MA) and S-phenyl mercapturic acid (S-PMA) in 301 oil refinery workers. The metabolites’ concentrations are lower and R is higher (100.66) in non-smokers (n=184) than in smokers (n=117, R=36.54). Non-smokers have lower S-PMA and a higher R in GSTT1 null genotypes than in positive, and a higher S-PMA and a lower R in GSTA1 wild type genotypes. In smokers the GSTT1 null genotype effect on both S-PMA and R is confirmed, and is also shown in GSTM1 null, but not in GSTA1 wild type genotypes. GSTT1 null polymorphism reduces the conjugation rate of benzene epoxide with GSH, and to a lesser extent also GSTTA1 mutant, GSTM1 null and NQO1 mutant genotypes. The activity of one GST is compensated by another in GSTM1 and GSTA1 defective subjects, but not in GSTT1 null genotypes, whose average S-PMA excretion is about 50% with respect to the positive ones, for the same benzene exposure. R showed to be a more sensitive marker for these effects than the metabolite levels.

Systemic exposure to PAHs and benzene in firefighters suppressing controlled structure fires.

Turnout gear provides protection against dermal exposure to contaminants during firefighting; however, the level of protection is unknown. We explored the dermal contribution to the systemic dose of polycyclic aromatic hydrocarbons (PAHs) and other aromatic hydrocarbons in firefighters during suppression and overhaul of controlled structure burns. The study was organized into two rounds, three controlled burns per round, and five firefighters per burn. The firefighters wore new or laundered turnout gear tested before each burn to ensure lack of PAH contamination. To ensure that any increase in systemic PAH levels after the burn was the result of dermal rather than inhalation exposure, the firefighters did not remove their self-contained breathing apparatus until overhaul was completed and they were >30 m upwind from the burn structure. Specimens were collected before and at intervals after the burn for biomarker analysis. Urine was analyzed for phenanthrene equivalents using enzyme-linked immunosorbent assay and a benzene metabolite (s-phenylmercapturic acid) using liquid chromatography/tandem mass spectrometry; both were adjusted by creatinine. Exhaled breath collected on thermal desorption tubes was analyzed for PAHs and other aromatic hydrocarbons using gas chromatography/mass spectrometry. We collected personal air samples during the burn and skin wipe samples (corn oil medium) on several body sites before and after the burn. The air and wipe samples were analyzed for PAHs using a liquid chromatography with photodiode array detection. We explored possible changes in external exposures or biomarkers over time and the relationships between these variables using non-parametric sign tests and Spearman tests, respectively. We found significantly elevated (P < 0.05) post-exposure breath concentrations of benzene compared with pre-exposure concentrations for both rounds. We also found significantly elevated post-exposure levels of PAHs on the neck compared with pre-exposure levels for round 1. We found statistically significant positive correlations between external exposures (i.e. personal air concentrations of PAHs) and biomarkers (i.e. change in urinary PAH metabolite levels in round 1 and change in breath concentrations of benzene in round 2). The results suggest that firefighters wearing full protective ensembles absorbed combustion products into their bodies. The PAHs most likely entered firefighters’ bodies through their skin, with the neck being the primary site of exposure and absorption due to the lower level of dermal protection afforded by hoods. Aromatic hydrocarbons could have been absorbed dermally during firefighting or inhaled during the doffing of gear that was off-gassing contaminants.

0032 Polymorphonuclear leukocytes phagocytic capacity in workers occupationally exposed to benzene

ObjectivesTo determine phagocytic capacity of PMN leukocytes in workers occupationally exposed to benzene.MethodCross-sectional study that included 54 workers of a paint manufacture company in Mexico City; exposure to benzene was...

Evaluation of chromosome aberration and micronucleus frequencies in blood lymphocytes of workers exposed to low concentrations of benzene

The frequency of chromosome aberrations (CA) and micronuclei (MN) was investigated in the peripheral lymphocytes of workers occupationally exposed to low or very low concentrations of benzene. The study included 43 exposed workers (all males), namely 19 fuel-tanker drivers and 24 filling-station attendants, and 31 male subjects with no occupational exposure to the toxicant (controls). Benzene exposure was verified by means of environmental monitoring with passive personal samplers (Radiello®), and through biological monitoring, i.e. by measurement of urinary trans,trans-muconic acid, S-phenylmercapturic acid and benzene. The frequency of CA and MN in peripheral lymphocytes was determined according to standard procedures. Exposure to benzene was found to be significantly higher for fuel-tanker drivers (median 246.6μg/m3) than for filling-station attendants (median 19.9μg/m3). Both groups had significantly higher exposure than controls (median 4.3μg/m3). No increased frequency of CA and MN was observed in either fuel-tanker drivers or filling-station attendants compared with controls. In all subjects examined as a single group, the frequency of MN was significantly dependent on age. Only in the fuel-tanker drivers was the frequency of MN found to depend not only on age, but also on exposure to benzene. In conclusion, the frequency of MN, but not of CA, could be influenced by exposure to benzene concentrations of up to one order of magnitude lower than the threshold limit value (time-weighted average).

Urinary S-phenylmercapturic Acid as a Key Biomarker for Measuring Occupational Exposure to Low Concentrations of Benzene in Chinese Workers

This study analyzed the level of urinary S-phenylmercapturic acid (U-SPMA) for low benzene exposure in a group of Chinese shoe-making workers. Urinary samples from 55 workers exposed to benzene at levels lower than 10 parts per million (ppm) were collected at postshift. U-SPMA level was determined using high-performance liquid chromatography/mass spectrography (HPLC/MS) method. Good linearity of U-SPMA was observed within the range from 10 to 320 μg/L (r = 0.9994). Concentration of airborne benzene ranged from 0.71 to 32.17 mg/m³, and three segments were divided with different levels of exposure (≤6.0, 6.0 to 10.0, 10 to 32.5 mg/m³), the median U-SPMA concentrations were 49.55, 102.15, and 335.69 μg/g Cr, respectively. A good linear correlation was found between U-SPMA levels and airborne benzene concentrations. The selected method could be applied for detecting other working conditions in China.

Determination of urinary 8-hydroxy-2'-deoxyguanosine, trans, trans-muconic acid, and S-phenylmercapturic acid by liquid chromatography-mass spectrometry

To establish a method for simultaneously determining the urinary concentrations of 8-hydroxy-2'-deoxyguanosine (8-OHdG), trans, trans-muconic acid (tt-MA), and S-phenylmercapturic acid (S-PMA) in subjects exposed to benzene. After being purified by a solid-phase extraction column, the urine samples were transferred to a liquid chromatography-mass spectrometry system, and the concentrations of 8-OHdG, tt-MA, and S-PMA were determined by external standard method. A C18 reversed-phase column was used as the chromatographic column, and methanol/acidic ammonium formate solution was used as the mobile phase for gradient elution. The mass spectrometer was operated in a multi-reaction monitoring mode. For tt-MA, the calibration curves were linear in the range of 10-1000 µg/L, and the recovery rates were over 90% (relative standard deviation (RSD) < 3%) at spiked levels of 50 µg/L and 500 µg/L. For S-PMA and 8-OHdG, the calibration curves were linear in the range of 1-100 µg/L, and the recovery rates were over 85% (RSD < 5%) at spiked levels of 5 µg/L and 50 µg/L. This determination method meets the requirement of Biological materials- of monitoring-Guide of development (WS/T 68-1996) and can be used for simultaneous determination of 8-OHdG, tt-MA, and S-PMA in urine.

Traffic-related air pollution. A pilot exposure assessment in Beirut, Lebanon

Traffic-related volatile organic compounds (VOCs) pollution has frequently been demonstrated to be a serious problem in the developing countries. Benzene and 1,3-butadiene (BD) have been classified as a human carcinogen based on evidence for an increased genotoxic and epigenotoxic effects in both occupational exposure assessment and in vivo/in vitro studies. We have undertaken a biomonitoring of 25 traffic policemen and 23 office policemen in Beirut, through personal air monitoring, assessed by diffusive samplers, as well as through the use of biomarkers of exposure to benzene and BD. Personal benzene, toluene, ethylbenzene, and xylene (BTEX) exposure were quantified by GC–MS/MS, urinary trans, trans-muconic acid (t,t-MA) by HPLC/UV, S-phenyl mercapturic acid (S-PMA), monohydroxy-butenyl mercapturic acid (MHBMA) and dihydroxybutyl mercapturic acid (DHBMA) by ultra-performance liquid chromatography-electrospray tandem mass spectrometry (UPLC/ESI(-)-MS/MS) in MRM (Multiple Reaction Monitoring) mode. We found that individual exposure to benzene in the traffic policemen was higher than that measured in traffic policemen in Prague, in Bologna, in Ioannina and in Bangkok. t,t-MA levels could distinguish between office and traffic policemen. However, median MHBMA levels in traffic policemen were slightly elevated, though not significantly higher than in office policemen. Alternatively, DHBMA concentrations could significantly distinguish between office and traffic policemen and showed a better correlation with personal total BTEX exposure. DHMBA, measured in the post-shift urine samples, correlated with both pre-shift MHMBA and pre-shift DHMBA. Moreover, there was not a marked effect of smoking habits on DHBMA. Taken together, these findings suggested that DHBMA is more suitable than MHBMA as biomarker of exposure to BD in humans. Traffic policemen, who are exposed to benzene and BD at the roadside in central Beirut, are potentially at a higher risk for development of diseases such as cancer than office policemen.

Biomonitoring of the general population living near a modern solid waste incinerator: A pilot study in Modena, Italy

Background and goalsAs part of the authorization process for the solid waste incinerator (SWI) in Modena, Italy, a human biomonitoring cross-sectional pilot study was conducted to investigate the degree to which people living and working in the proximity of the plant were exposed to SWI emissions. MethodsBetween May and June 2010, 65 subjects living and working within 4km of the incinerator (exposed) and 103 subjects living and working outside this area (unexposed) were enrolled in the study. Blood, serum and urinary metals (Pb, Cd, Cu, Zn, Hg, Mn, Ni), urinary benzene, toluene, xylene (BTEX), S-phenylmercapturic acid (SPMA), and urinary polycyclic aromatic hydrocarbons (PAHs) were analysed. Information about lifestyle, anthropometric characteristics, residence, and health status was collected by a self-administered questionnaire. Exposure to particulate matter (PM) emitted from the SWI was estimated using fall-out maps from a quasi-Gaussian dispersion model. A multiple linear regression analysis investigated the relationship between biomarkers and the distance of a subject's place of residence from the SWI plant or the exposure to PM. ResultsUrinary BTEX and SPMA and blood, serum and urinary metals showed no differences between exposed and unexposed subjects. PAHs were higher in exposed than in unexposed subjects for phenanthrene, anthracene, and pyrene (median levels: 9.5 vs. 7.2ng/L, 0.8 vs. <0.5ng/L and 1.6 vs. 1.3ng/L, respectively, p<0.05). Multiple linear regression analysis showed that blood Cd and Hg and urinary Mn, fluorene, phenanthrene, anthracene and pyrene were inversely correlated to the distance of a subject's residence from the SWI. Urinary Mn, fluorene and phenanthrene were directly correlated to PM exposure. ConclusionsThis study, although not representative of the general population, suggests that specific biomarkers may provide information about the degree of exposure the subjects working and living in the proximity of the SWI plant may have to emissions from that facility.

Urinary S-PMA related to indoor benzene and asthma in children

Introduction: Benzene is a ubiquitous pollutant of both indoor and outdoor environments which impacts on respiratory health. Our aim was to relate urinary S-phenylmercapturic acid (S-PMA), a biomarker of benzene exposure, to benzene concentrations and related sources at home and asthma in a population-based sample of children.Methods: Exposure to benzene was assessed in the dwellings of 63 children (32 asthmatics and 31 controls) through the identification of sources of benzene and in situ assessments with passive samplers. The determination of urinary S-PMA was obtained by liquid chromatography–mass spectrometry.Results: At home, asthmatics were significantly more polluted by benzene levels from ambient sampling than controls (p ≤ 0.05). Benzene exposure significantly aggravated asthma symptoms overall in non-atopic children (OR = 10.10; 95% confidence interval: 10.10). Urinary S-PMA was significantly associated with benzene concentrations in the entire population (regression coefficient = 0.28, 95% CI: 0.07–0.49; p < 0.05) and asthma (OR = 7.69; 95% CI: 1.37–42.52 for an increase of 1 µg/g creatinine of urinary S-PMA). However, after adjustment for environmental tobacco smoking exposure, familial allergy, age and sex, the latter relationship was no more significant (OR = 4.95; 95% CI: 0.91–27.4, p < 0.10). Both benzene concentrations and urinary S-PMA concentrations were higher in dwelling built after 1948 and in flats.Conclusions: Our study suggests a relationship between childhood asthma and benzene concentrations at home, even at low levels of this pollutant. This was confirmed when considering urinary S-PMA, which was related to both benzene concentrations and asthma. Further epidemiological and toxicological studies are needed to confirm our results.

Abstract 1502: Urinary biomarkers of polycyclic aromatic hydrocarbon and volatile organic carcinogens in relation to lung cancer development in lifelong never smokers - The Shanghai Cohort Study.

Abstract Background: In the United States, 10-15% of lung cancer victims are lifelong never smokers. Non-smoking related lung cancer alone ranks as the 6th most frequently diagnosed cancer. The etiological factors for non-smoking lung cancer are unclear. Although strong evidence supports a major role for polycyclic aromatic hydrocarbon (PAH) as causes of lung cancer in smokers, epidemiological studies prospectively investigating biomarkers of PAH and volatile organic carcinogens in relation to lung cancer risk among never smokers are lacking. Methods: A nested case-control study of lung cancer among never smokers was conducted within the Shanghai Cohort Study, a prospective cohort of 18,244 Chinese men aged 45-64 years at enrollment during 1986-1989. After more than 20 years of follow-up, we identified 96 incident lung cancer cases among never smokers. For each case, we randomly chose one control among cohort participants who were never smokers. The control was matched to the index case by age (±2 years), date of urine collection (±1 month) and neighborhood of residence. We quantified urinary free cotinine, 3-hydroxyphenanthrene (3-OH-Phe), total hydroxyphenanthrenes (the sum of 1-, 2-, 3-, and 4-OH-Phe) (total OH-Phe), r-1,t-2,3,c-4-tetrahdroxy-1,2,3,4-tetrahydrophenanthrene (PheT), mercapturic acid metabolites of acrolein [3-hydroxypropyl mercapturic acid (HPMA)], benzene [S-phenyl mercapturic acid (SPMA)], crotonaldehyde [4-hydroxybut-2-yl mercapturic acid (HBMA)], and ethylene oxide [2-hydroxyethyl mercapturic acid (HEMA)]. Self-reported never smokers whose urinary free cotinine was greater than 20 ng/ml were excluded from the present analysis for their potential use of tobacco. The odds ratio (OR) and 95% confidence interval (CI) for lung cancer for each urinary biomarker was estimated using an unconditional logistic regression method. Results: Among never smokers, urinary levels of all 3 measured PAH biomarkers were statistically significantly higher in cases than controls. The geometric means (pmol/mg creatinine) of total OH-Phe, 3-OH-Phe and PheT were 19.10 (in cases) vs 16.08 (in controls) (P = 0.017); 6.64 vs 5.44 (P = 0.011); and 19.84 vs 16.10 (P = 0.035), respectively. Compared with the lowest quartile, ORs (95% CIs) for lung cancer for the highest quartile were 2.59 (1.01-6.65) for total OH-Phe, 3.10 (1.12-7.75) for 3-OH-Phe, and 2.98 (1.13-7.87) for PheT (all Ptrend &amp;lt;0.05). There was no statistically significant difference in urinary levels of HPMA, SPMA, HBMA and HEMA between cases and controls. Conclusion: This is the first prospective study that demonstrates a positive association between urinary biomarkers of PAH and lung cancer risk among never smokers. Given its ubiquitous presence in the environment, PAH could account for large proportion of non-smoking related lung cancer. 1 Citation Format: Jian-Min Yuan, Yu-Tang Gao, Sharon Murphy, Steven G. Carmella, Renwei Wang, Heather H. Nelson, Stephen S. Hecht. Urinary biomarkers of polycyclic aromatic hydrocarbon and volatile organic carcinogens in relation to lung cancer development in lifelong never smokers - The Shanghai Cohort Study. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1502. doi:10.1158/1538-7445.AM2013-1502

S-phenylmercapturic acid (S-PMA) levels in urine as an indicator of exposure to benzene in the Kinshasa population

Data on human exposure to chemicals in Africa are scarce. A biomonitoring study was conducted in a representative sample of the population in Kinshasa (Democratic Republic of Congo) to document exposure to benzene. S-phenylmercapturic acid (S-PMA) was measured by LC-MS/MS in spot urine samples from 220 individuals (50.5% women), aged 6-70 years living in the urban area and from 50 additional subjects from the sub-rural area of Kinshasa. Data were compiled as arithmetic means, geometric means, percentile 95th and range expressed in μg/L. Overall, living in urban Kinshasa was associated with increased levels of S-PMA in urine as compared to a population living in the sub-rural area. Increased levels were also found by comparison with some date from literature. This study reveals the high benzene exposure of the Kinshasa population requiring the determination of benzene concentrations in ambient air of Kinshasa and limit values for the protection of human health.

Mixed Extractant-Dispersive Liquid Phase Microextraction Based on Solidification of Floating Organic Drop for Determination of S -phenylmercapturic Acid in Urine

A method of dispersive liquid phase microextraction based on solidification of floating organic drop(SFO-DLLME) with mixed extractant by high performance liquid chromatography(HPLC) for the determination of S-phenylmercapturic acid(SPMA) in urine was established.Detailed research on the conditions of microextraction was evaluated in the experiment.An aliquot of 20 mL of urine sample was adjusted to pH 2.0 and 7.2 g NaCl was added to increase the ionic strength.Then,100 μL mixed solvent(1-dodecanol/chloroform,1.8 ∶ 1,V/V) as extractant and 100 μL methanol as dispersive agent were injected into sample solution.The solution was shaken to disperse the extractant.The extraction solvent could be floated on the surface of the solution with the help of centrifugation and solidified at -20 ℃.Then the solid organic phase was transferred to EP tube and melted at room temperature.The supernatant of mixed extraction solvent was injected into HPLC system for.The analytical method showed good linearity in the range of 0.025-1.25 mg/L SPMA.The detection limit was 0.019 mg/L.The intra-day and inter-day precisions(relative standard deviation,RSD) of the method were 2.2%-5.4% and 2.5%-6.1%,respectively.The method was applied for determination of SPMA in human urine with satisfactory results.The spiked recoveries ranged from 86.8%-99.9%.The method was simple,fast and suitable for batch analysis of SPMA in urine samples.

A rapid and sensitive liquid chromatography-tandem mass spectrometry method for the quantitation of S-phenylmercapturic acid in human urine

A rapid, sensitive and robust method based on high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for the quantitation of S-phenylmercapturic acid (S-PMA), a metabolite of benzene, in human urine. Urine samples to which S-phenylmercapturic acid-d2 (S-PMA-d2) had been added as an internal standard (I.S.) were subjected to liquid–liquid extraction (LLE) with ethyl acetate in an acidic environment. S-PMA and the I.S. were separated on a C18 column and detected in negative ion and multiple reaction monitoring mode within 1.8 min. The assay was fully validated and exhibited good linearity in the concentration range of 0.2–200 ng mL−1, with a lower limit of quantitation of 0.2 ng mL−1. The intra- and inter-day precisions were <8.1%, with a relative error <6.9%. The short run time coupled with the efficient one-step LLE sample preparation procedure makes the proposed method a promising strategy for the high-throughput and cost-effective analysis of urinary S-PMA levels, which is required to evaluate the health risk of exposure to benzene or cigarette smoking.

Urinary Benzene Biomarkers and DNA Methylation in Bulgarian Petrochemical Workers: Study Findings and Comparison of Linear and Beta Regression Models

Chronic occupational exposure to benzene is associated with an increased risk of hematological malignancies such as acute myeloid leukemia (AML), but the underlying mechanisms are still unclear. The main objective of this study was to investigate the association between benzene exposure and DNA methylation, both in repeated elements and candidate genes, in a population of 158 Bulgarian petrochemical workers and 50 unexposed office workers. Exposure assessment included personal monitoring of airborne benzene at work and urinary biomarkers of benzene metabolism (S-phenylmercapturic acid [SPMA] and trans,trans-muconic acid [t,t-MA]) at the end of the work-shift. The median levels of airborne benzene, SPMA and t,t-MA in workers were 0.46 ppm, 15.5 µg/L and 711 µg/L respectively, and exposure levels were significantly lower in the controls. Repeated-element DNA methylation was measured in Alu and LINE-1, and gene-specific methylation in MAGE and p15. DNA methylation levels were not significantly different between exposed workers and controls (P>0.05). Both ordinary least squares (OLS) and beta-regression models were used to estimate benzene-methylation associations. Beta-regression showed better model specification, as reflected in improved coefficient of determination (pseudo R2) and Akaike’s information criterion (AIC). In beta-regression, we found statistically significant reductions in LINE-1 (−0.15%, P<0.01) and p15 (−0.096%, P<0.01) mean methylation levels with each interquartile range (IQR) increase in SPMA. This study showed statistically significant but weak associations of LINE-1 and p15 hypomethylation with SPMA in Bulgarian petrochemical workers. We showed that beta-regression is more appropriate than OLS regression for fitting methylation data.

Urinary trans, trans-muconic acid and S-phenylmercapturic acid are indicative of exposure to urban benzene pollution during childhood

The aims of the study were to evaluate the feasibility of urinary trans, trans-muconic acid (u-t,t-MA) and urinary S-phenylmercapturic acid (u-SPMA) as markers of exposure to urban benzene pollution for biomonitoring studies performed on children and to investigate the impact that creatinine correction may have on the classification of children exposure status.U-t,t-MA, u-SPMA, u-cotinine, and u-creatinine levels were measured in urine samples of 396 Italian children (5–11years) living in three areas with different degrees of urbanisation (very, fairly and non-urban).The median u-SPMA levels significantly increased with increased urbanisation: non-urban (0.19μg/L; 0.22μg/g creatinine)<fairly urban (0.28μg/L; 0.28μg/g creatinine)<very urban group (0.92μg/L; 0.90μg/g creatinine). Differences in the levels of u-t,t-MA excretion related to the degree of urbanisation were revealed only by multivariate analyses. Neither u-SPMA nor u-t,t-MA levels were influenced by environmental tobacco smoke (ETS) exposure.Athletic activity during the sampling day was negatively associated with u-SPMA in the model built with u-SPMA adjusted for creatinine, but not in the model where unadjusted u-SPMA was used. This finding demonstrates that u-creatinine correction may alter the results when an independent variable is unrelated to the chemical concentration itself but is related to the u-creatinine levels.These results suggest that both u-SPMA and u-t,t-MA are indicative for assessing environmental benzene exposure in children (exposed and unexposed to ETS) when urine sample is collected at the end of the day.However, u-SPMA is more reliable because u-t,t-MA, also a metabolite of sorbic acid, is less specific for exposure to low levels of benzene.To avoid the possible confounding effect of creatinine correction, it is better to use u-creatinine as additional independent variable in multiple linear regression analyses for evaluating the independent role of the covariates on the variability of u-t,t-MA and u-SPMA levels.

Evaluation and Comparison of Urinary Metabolic Biomarkers of Exposure for the Jet Fuel JP-8

A study of workers exposed to jet fuel propellant 8 (JP-8) was conducted at U.S. Air Force bases and included the evaluation of three biomarkers of exposure: S-benzylmercapturic acid (BMA), S-phenylmercapturic acid (PMA), and (2-methoxyethoxy)acetic acid (MEAA). Postshift urine specimens were collected from various personnel categorized as high (n = 98), moderate (n = 38) and low (n = 61) JP-8 exposure based on work activities. BMA and PMA urinary levels were determined by high-performance liquid chromatography–tandem mass spectrometry (HPLC-MS/MS), and MEAA urinary levels were determined by gas chromatography–mass spectrometry (GC-MS). The numbers of samples determined as positive for the presence of the BMA biomarker (above the test method's limit of detection [LOD = 0.5 ng/ml]) were 96 (98.0%), 37 (97.4%), and 58 (95.1%) for the high, moderate, and low (control) exposure workgroup categories, respectively. The numbers of samples determined as positive for the presence of the PMA biomarker (LOD = 0.5 ng/ml) were 33 (33.7%), 9 (23.7%), and 12 (19.7%) for the high, moderate, and low exposure categories. The numbers of samples determined as positive for the presence of the MEAA biomarker (LOD = 0.1 μg/ml) were 92 (93.4%), 13 (34.2%), and 2 (3.3%) for the high, moderate, and low exposure categories. Statistical analysis of the mean levels of the analytes demonstrated MEAA to be the most accurate or appropriate biomarker for JP-8 exposure using urinary concentrations either adjusted or not adjusted for creatinine; mean levels of BMA and PMA were not statistically significant between workgroup categories after adjusting for creatinine.

Biomarkers of exposure to aromatic hydrocarbons and methyl tert-butyl ether in petrol station workers

This cross-sectional study was aimed at reconstructing the exposure to gasoline in 102 petrol station attendants by environmental and biological monitoring of benzene, toluene, ethylbenzene and xylene (BTEX) and biomonitoring of methyl tert-butyl ether (MTBE). Airborne BTEX were higher for manual refuelers than self-service assistants and were highly correlated with each other. Significant relationships were found between airborne BTX and the corresponding urinary solvents (U-BTX) and beween airborne B and urinary MTBE (U-MTBE). Smokers eliminated higher values of U-B, trans,trans-muconic (t,t-MA) and S-phenylmercapturic (S-PMA) acids but not U-MTBE. All these biomarkers were, however, significantly raised during the shift, independently from smoking. Linear regression confirmed that occupational exposure was a main predictor of U-MTBE, U-B and S-PMA values, both the latter confounded by smoking habits. The study supports the usefulness of biomonitoring even at low exposure levels.

Assessment of occupational exposure to benzene, toluene and xylenes in urban and rural female workers

ObjectivesThis is the first research study to compare among female, non-smoker workers: (a) the exposure to benzene, toluene and xylenes (BTXs) in urban air during work in the street (traffic policewomen, TP) vs. work in vehicles (police drivers, PD); (b) the exposure to BTXs in urban environments (in street and in car) vs. rural environments (roadwomen, RW); (c) the values of blood benzene, urinary trans, trans muconic acid (t,t-MA) and urinary S-phenylmercapturic acid (S-PMA) in urban areas (in street and in car) vs. rural areas. MethodsPassive personal samplings and data acquired using fixed monitoring stations located in different areas of the city were used to measure environmental and occupational exposure to BTXs during the work shift in 48 TP, 21 PD and 22 RW. In the same study subjects, blood benzene, t,t-MA and S-PMA were measured at the end of each work shift. ResultsPersonal exposure of urban workers to benzene seemed to be higher than the exposure measured by the fixed monitoring stations. Personal exposure to benzene and toluene was (a) similar among TP and PD and (b) higher among urban workers compared to rural workers. Personal exposure to xylenes was (a) higher in TP than in PD and (b) higher among urban workers compared to rural workers. Blood benzene, t,t-MA and S-PMA levels were similar among TP and PD, although the blood benzene level was significantly higher in urban workers compared to rural workers. In urban workers, airborne benzene and blood benzene levels were significantly correlated. ConclusionsBenzene is a human carcinogen, and BTXs are potential reproductive toxins at low dose exposures. Biological and environmental monitoring to assess exposure to BTXs represents a preliminary and necessary tool for the implementation of preventive measures for female subjects working in outdoor environments.

Environmental and biological monitoring of benzene in traffic policemen, police drivers and rural outdoor male workers

To evaluate exposure to benzene in urban and rural areas, an investigation into personal exposure to benzene in traffic policemen, police drivers and rural (roadmen) male outdoor workers was carried out. Personal samples and data acquired using fixed monitoring stations located in different areas of the city were used to measure personal exposure to benzene in 62 non-smoker traffic policemen, 22 police drivers and 57 roadmen. Blood benzene, urinary trans-trans muconic acid (t,t-MA) and S-phenyl-mercapturic acid (S-PMA) were measured at the end of work shift in 62 non-smoker traffic policemen, 22 police drivers and 57 roadmen and 34 smoker traffic policemen, 21 police drivers and 53 roadmen. Exposure to benzene was similar among non-smoker traffic policemen and police drivers and higher among non-smoker urban workers compared to rural workers. Blood benzene, t,t-MA and S-PMA were similar among non-smoker traffic policemen and police drivers; blood benzene and t,t-MA were significantly higher in non-smoker urban workers compared to rural workers. Significant increases in t,t-MA were found in smokers vs. non-smokers. In non-smoker urban workers airborne benzene and blood benzene, and t,t-MA and S-PMA were significantly correlated. This study gives an evaluation of the exposure to benzene in an urban area, comparing people working in the street or in cars, to people working in a rural area. Benzene is a certain carcinogen for humans. The results we showed should lead to more in-depth studies about the effects on health of these categories of workers.

Influence of glutathione S-transferases polymorphisms on biological monitoring of exposure to low doses of benzene

The environmental and biological monitoring of benzene exposure is crucial to prevent the toxic effects of this solvent in workers. The degree of correlation, however, between the two and of different biomarkers among them varies, particularly at low levels of exposure, depending on various factors, including variability in metabolizing enzymes and smoking habits. To investigate these further, a cohort of 28 petrochemical workers (6 smokers and 22 non smokers) was monitored throughout ten consecutive days, on two occasions, two years apart, by collecting in total 173 environmental and biological samples. The airborne benzene levels, the urinary t,t-muconic acid (t,t-MA) and S-phenylmercapturic acid (S-PMA) concentrations, and the glutathione S-transferases (GST) M1 and T1 genotypes were measured. S-PMA was the only metabolite statistically correlated with airborne benzene levels (r=0.447, P<0.0001), particularly in non smokers (r=0.667, P<0.0001), the smoking habit being the only variable influencing metabolite excretion. Finally, a reduced S-PMA excretion was found to be associated with the GSTT1, but not the GSTM1, null genotype. In conclusion, the results show that S-PMA, but not t,t-MA, is able to monitor exposure to low benzene concentrations and confirm that the GSTT1 null genotype has a significant influence on metabolite excretion. The influence of the GSTT1 null genotype, however, was low, even when studying each subject with several urine samples.