Low-Dose Benzene Exposure Monitoring of Oil Refinery Workers: Inhalation and Biomarkers (original) (raw)
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Toxicology Letters, 2018
The aim of the study was to investigate the effect of various factors that modulate the metabolism of benzene, including smoking habits, metabolic genotype of GST and co-exposure to toluene, on the levels of three biomarkers, i.e. urinary benzene (UB), S-phenylmercapturic acid (SPMA) and t,tmuconic acid (t,t-MA), in 146 refinery workers exposed to low levels of air benzene (AB) in the range <1.5-529.2 µg/m 3 (mean value 32.6 µg/m 3). The study confirmed the validity of SPMA as a good biomarker of benzene exposure even at low levels of exposure. It was also confirmed that cigarette smoking is the main confounding factor when assessing biological monitoring data of occupational exposure to AB. Our data indicate that the GSTT1, but not the GSTM1 genotype, significantly increases the urinary levels of SPMA, even at low levels of exposure. It is not known, though, whether subjects with a GSTT1 "null" genotype may be more susceptible to the effects of benzene. Finally, environmental toluene appears to inhibit the metabolism of benzene to SPMA even at low concentrations, also resulting in an underestimation by SPMA levels of the actual exposure of workers to benzene.
Health Scope, 2015
Background: Solvents such as benzene and toluene are commonly used in tire manufacturing, and significant occupational exposure to these chemicals adversely affects the health of workers. In biological monitoring, a complementary method for personal monitoring, the internal absorbed dose is measured and individual, environmental, and exposure differences are taken into consideration. Objectives: The present study evaluated external doses by personal monitoring and investigated a more practical approach to biological monitoring by measuring the internal doses of benzene and toluene in workers involved in tire manufacturing. Materials and Methods: Personal monitoring of 100 workers in tire factories A and B (n = 50 samples from each factory, n = 100 total personal samples) was performed using the national institute for occupational safety and health 1501 method. Biological monitoring of the workers was performed by collecting exhaled air in Tedlar ® bags (n = 100). Personal and biological samples were analyzed by a gas chromatograph equipped with a flame ionization detector. Data were analyzed by independent t-test and correlation coefficients. Results: There were no significant differences between factories with respect to worker age or work history. Personal exposure to benzene exceeded the current threshold limit value in 68% of workers. Occupational exposure to benzene and toluene as external (i.e. in the breathing area) and internal doses (i.e. in the exhaled air) were significantly higher in factory B than factory A. In addition, the external and internal doses of both compounds were significantly correlated. Conclusions: The workplace conditions of tire factories must be improved. The biological exposure index can be calculated by determining the unchanged benzene and toluene concentrations in exhaled air; this can be used as a more reliable method for personal monitoring.
La Medicina Del Lavoro, 2012
The aim of the study was to investigate the effect of various factors that modulate the metabolism of benzene, including smoking habits, metabolic genotype of GST and co-exposure to toluene, on the levels of three biomarkers, i.e. urinary benzene (UB), S-phenylmercapturic acid (SPMA) and t,tmuconic acid (t,t-MA), in 146 refinery workers exposed to low levels of air benzene (AB) in the range <1.5-529.2 µg/m 3 (mean value 32.6 µg/m 3). The study confirmed the validity of SPMA as a good biomarker of benzene exposure even at low levels of exposure. It was also confirmed that cigarette smoking is the main confounding factor when assessing biological monitoring data of occupational exposure to AB. Our data indicate that the GSTT1, but not the GSTM1 genotype, significantly increases the urinary levels of SPMA, even at low levels of exposure. It is not known, though, whether subjects with a GSTT1 "null" genotype may be more susceptible to the effects of benzene. Finally, environmental toluene appears to inhibit the metabolism of benzene to SPMA even at low concentrations, also resulting in an underestimation by SPMA levels of the actual exposure of workers to benzene.
Environmental and biological monitoring of benzene exposure in a cohort of Italian taxi drivers
Toxicology Letters, 2006
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.
Validation and evaluation of biomarkers in workers exposed to benzene in China
Research report (Health Effects Institute), 2003
This study was conducted to validate biomarkers for early detection of benzene exposure and effect in 2 phases. The main purpose of phase 1 was to determine whether these biomarkers could reliably detect differences between workers with high exposure levels and unexposed subjects, which is the minimal screening criterion for a biomarker assay. Phase 2 of the study mainly focused on evaluating the exposure-response relation, confounding factors, and sensitivities of biomarkers for low benzene exposures. The Chinese occupational population studied had a broad range of benzene exposures. On the day of biological sample collection, exposures ranged from 0.06 to 122 ppm with a median exposure of 3.2 ppm. The median of the 4-week mean benzene exposures was 3.8 ppm, and the median lifetime cumulative exposure was 51.1 ppm-years. Compared with benzene levels in collected samples, toluene levels were relatively high, with a median of 12.6 ppm (mean, 26.3 ppm), but xylene levels were low, wit...
Occupational and Environmental Medicine, 1993
Recently, the determination of S-phenylmercapturic acid (S-PMA) in urine has been proposed as a suitable biomarker for the monitoring of low level exposures to benzene. In the study reported here, the test has been validated in 12 separate studies in chemical manufacturing plants, oil refineries, and natural gas production plants. Parameters studied were the urinary excretion characteristics of S-PMA, the specificity and the sensitivity of the assay, and the relations between exposures to airborne benzene and urinary S-PMA concentrations and between urinary phenol and S-PMA concentrations. The range of exposures to benzene was highest in workers in chemical manufacturing plants and in workers cleaning tanks or installations containing benzene as a component of natural gas condensate. Urinary S-PMA concentrations were measured up to 543 pg/g creatinine. Workers' exposures to benzene were lowest in oil refineries and S-PMA concentrations were comparable with those in smoking or nonsmoking control persons (most below the detection limit of 1 to 5 pg/g creatinine). In most workers S-PMA was excreted in a single phase and the highest S-PMA concentrations were at the end of an eight hour shift. The average half life of elimination was 9-0 (SD 4 5) hours (31 workers). Tentatively, in five workers a second phase of elimination was found with an average half life of 45 (SD 4) hours.
Ecotoxicology and environmental safety, 2017
Elevated emissions of volatile organic compounds, including benzene, toluene, ethylbenzene, and o, p, and m-xylenes (BTEX), are an occupational health concern at oil transfer stations. This exploratory study investigated personal exposure to BTEX through environmental air and urine samples collected from 50 male workers at a major oil distribution company in Iran. Airborne BTEX exposures were evaluated over 8h periods during work-shift by using personal passive samplers. Urinary BTEX levels were determined using solid-phase microextraction with gas chromatography mass spectrometry for separation and detection. Mean exposure to ambient concentrations of benzene differed by workers' job type: tanker loading workers (5390μg/m(3)), tank-gauging workers (830μg/m(3)), drivers (81.9μg/m(3)), firefighters (71.2μg/m(3)) and office workers (19.8μg/m(3)). Exposure across job type was similarly stratified across all personal exposures to BTEX measured in air samples with maximum concentrati...
Benzene in blood as a biomarker of low level occupational exposure
Science of The Total Environment, 1999
The occupational airborne exposure to benzene of 150 workers employed in petrol stations and a refinery plant was assessed using personal sampling pumps. All workers provided blood samples after the end of work and on the following morning before resuming work. Benzene concentrations in the blood of 243 non-occupationally-exposed subjects were also measured. The median occupational benzene exposure for all 150 workers studied was 80 grm 3 . Overall median blood benzene of all workers was 251 ngrl at the end of the shift, and 174 ngrl the following morning. The benzene concentrations measured in blood collected the following morning proved to be significantly lower than those measured at the end of the shift. Median blood benzene for the 243 'normal' subjects was 128 ngrl, which was significantly lower than that measured in the workers before a new work shift. The median blood benzene Ž concentration was significantly higher in smokers than in non-smokers, both in the general population 210 ngrl vs.