Indicators of benzene emissions and exposure in Bangkok street

Ambient benzene measurements were conducted for the first time at four air monitoring sites in the Bangkok metropolitan region (BMR), from January to December 2001. Analytical results show that the mean benzene concentrations range from 42.4 micro g/m(3) at the Din Daeng urban site to 15.1 micro g/m(3) at the Chaeng Wattana suburban site. The monitoring results show that at a larger distance from the roadside or a higher level from the street surface, the level of benzene decreases. Analysis of the ambient benzene concentrations was carried out with reference to meteorological influences and traffic density. In traffic analysis, the combined effects of street topography and traffic flows established high impact on the overall benzene concentration in Bangkok. Statistical analysis shows good correlations of blood benzene levels and trans, trans-muconic acid with ambient benzene and demonstrated substantial exposure from traffic.     

Exposure to emissions from gasoline within automobile cabins.

Gasoline is emitted from automobiles as uncombusted fuel and via evaporation. Volatile organic compounds (VOC) from gasoline are at higher levels in roadway air than in the surrounding ambient atmosphere and penetrate into automobile cabins, thereby exposing commuters to higher levels than they would experience in other microenvironments. Measurements of VOC concentrations and carbon monoxide were made within automobiles during idling, while driving on a suburban route in New Jersey, and on a commute to New York City. Concentrations of VOC from gasoline were determined to be elevated above the ambient background levels in all microenvironments while VOC without a gasoline source were not. The variability of VOC concentrations with location within the automobile was determined to be smaller than inter-day variability during idling studies. VOC and carbon monoxide levels within the automobile cabin differed among the different routes examined. The levels were related to traffic density and were inversely related to driving speed and wind speed. Overall, daily VOC exposure for gasoline-derived compounds during winter commuting in New Jersey was estimated to range between 5 and 20% and constituted between 15 and 40% of an individual's daily exposure based on comparison to urban and suburban settings, respectively. VOC exposure during commuting in Southern California was estimated to range between 15 and 60%.     

上海市闵行区汽车销售服务企业喷漆作业场所“苯系物”浓度现况调查

目的了解上海市闵行区汽车销售服务企业喷漆作业场所中苯、甲苯、二甲苯浓度,以预防苯系物和其他危害因素的联合作用对作业人员健康造成危害。方法选择该区内的汽车销售服务企业为调查对象,随机抽取19家进行喷漆作业场所监督监测和现场调查。结果抽检的该区汽车销售服务企业喷漆作业场所空气中苯、甲苯、二甲苯的浓度多数分别为0.6、1.2和1.6 mg/m3,大多低于检出限。结论喷漆作业岗位空气中的苯、甲苯、二甲苯浓度虽然低于国家标准,但由此会产生的联合作用造成的职业危害潜在风险仍不可低估。     

Health effects of exposure to automobile exhaust--V. exposure of toll booth operators to automobile exhaust.

The exposures of automobile toll booth collectors in the Boston area to selected air contaminants were monitored during the four seasons from 1972 to 1974. The highest carbon monoxide concentrations were found at the in-city toll booths and the highest lead levels at the surburban booths. Biological monitoring for carbon monoxide and lead exposure were closely related to airborne contaminant levels. The study supports the need for environmental control for toll booths located at busy highway and tunnels.     

Mutual metabolic suppression between benzene and toluene in man

Summary The exposure intensity during a shift and the metabolite levels in the shift-end urine were examined in male workers exposed to either benzene (65 subjects; the benzene group), toluene (35 subjects; the toluene group), or a mixture of both (55 subjects; the mixture group). In addition, 35 non-exposed male workers (the control group) were similarly examined for urinary metabolites to define background levels. A linear relationship was established between the intensity of solvent exposure and the corresponding urinary metabolite levels (i.e. phenol, catechol and quinol from benzene, and hippuric acid and o-cresol from toluene) in each case when one of the three exposed groups was combined with the control group for calculation. Comparison of regression lines in combination with regression analysis disclosed that urinary levels of phenol and quinol (but not catechol) were lower in the mixture group than in the benzene group when the intensities of exposure to benzene were comparable, indicating that the biotransformation of benzene to phenolic compounds (excluding catechol) in man is suppressed by co-exposure to toluene. Conversely, metabolism of toluene to hippuric acid was suppressed by benzene co-exposure. Conversion of toluene to o-cresol was also reduced by benzene, but to a lesser extent. The significance of the present findings on the mutual suppression of metabolism between benzene and toluene is discussed in relation to solvent toxicology and biological monitoring of exposure to the solvents.