Health effects of gasoline refueling vapors and measured exposures at service stations

Liquid gasoline is a complex mixture of at least 150 hydrocarbons with about 60-70% alkanes (paraffins), 25-30% aromatics, and 6-9% alkenes. In order to evaluate the potential for health effects from inhaling gasoline vapors, it is essential to understand the major differences in the composition of vapors versus liquid gasoline. The small chain, low carbon-numbered components are more volatile and thus in higher percentages in the vapor phase than the larger and heavier molecules. It is noteworthy that the concentrations of aromatics (the more toxic of the gasoline components), are depleted to about 2% in the vapor phase, with the light paraffins (the less toxic) enriched to about 90%. Actual measurements of vapor exposure at service stations confirm that the vapor composition is primarily to low weight alkanes although benzene is also emitted and represents the chemical of greatest concern. A perceived health concern from inhaling gasoline vapors is the potential for carcinogenicity based on the induction of kidney tumors in male rats and liver tumors in female mice exposed to wholly-vaporized gasoline. However, the results of the animal studies are of questionable relevance for human risk assessment due to the unique mechanism operative only in the male rat and since the exposure was to wholly-vaporized gasoline rather than the gasoline vapor mixture to which humans are exposed. Recent research supports the hypothesis that branched-chain-alkanes bind to a globulin specific to make rats, alpha 2-u-globulin. The protein complex can not be degraded in the usual manner so that protein accumulation occurs in renal cells, leading to cytotoxicity, death, proliferation, and with prolonged exposure, kidney cancer. The results of epidemiology studies fail to link an increase in cancer to exposure to gasoline vapors.     

气相色谱法同时测定工作场所中甲醇和苯系物

目的：探讨一次采样气相色谱同时测定工作场所中甲醇、苯、甲苯和二甲苯的方法。方法：用活性炭管采集、二硫化碳解吸、HP123-0732（DB-1701）型毛细管柱分离、氢火焰检测器检测、气相色谱法同时测定工作场所中甲醇、苯、甲苯和二甲苯,探索检测条件,并进行方法学研究。结果：该方法最低检测浓度：甲醇0.047 mg/m3,苯0.033 mg/m3,甲苯0.037 mg/m3,二甲苯0.041 mg/m3;相对标准偏差：甲醇在0.46%～1.89%之间,苯在0.855～4.74%之间,甲苯在1.35%～3.45%之间,二甲苯在1.87%～5.68%之间;平均采样效率为甲醇97.6%,苯94.4%,甲苯98.5%,二甲苯100.8%;平均解吸效率为甲醇98.8%,苯95.6%,甲苯97.5%,二甲苯99.8%。结论：该方法简单、适用,重现性好,灵敏度高,结果令人满意。     

Measurements of exposure concentrations of benzene, toluene and xylene, and amounts of respiratory uptake

With respect to benzene, toluene, and o-, m- and p-xylene contained in indoor air, this study determined the amounts of their uptake through the human respiratory system using the difference between concentrations in inhalation and exhalation, and examined their relationship to concentrations in blood and urine measured before and after exposure. At relatively high concentrations, respiratory absorption of these compounds tended to increase rapidly in the early stage of exposure but decrease after several hours. It was also confirmed that concentrations of these compounds in both blood and urine increased during the first 3 hours of exposure. These results suggested that measurements of concentrations in inhalation and exhalation may provide a simple method for estimating the extent of respiratory exposure to these substances.     

Quantitation of urinary metabolites of toluene,xylene, styrene,ethylbenzene, benzene and phenol by automated high performance liquid chromatography

Summary An automated high performance liquid chromatographic method (HPLC) for the direct determination of urinary concentrations of hippuric acid (HA), and o-, m- and p-methyl hippuric acids (MHAs), metabolites of toluene and o-, m-, and p-xylenes, and of urinary phenyl glyoxylic acid (PGA) and mandelic acid (MA), metabolites of styrene or ethylbenzene, is described. Methanol was added to urine, the mixture was centrifuged and the supernatant was injected into HPLC. A stainless-steel column packed with octadecyl silanized silicate was used and the mobile phase was a mixed solution of 5 mM potassium phosphate monobasic/acetonitrile (90/10). The method is simple and specific. Urine can be analyzed without solvent extraction. Analysis can be performed satisfactorily within 45 min for samples containing HA, MHAs, PGA and MA, and within 15 min for those containing HA, PGA and MA. Another automated HPLC method for the determination of urinary concentrations of phenylsulfate (PhS) and phenylglucuronide (PhG), metabolites of benzene and phenol, is also described. Urine was centrifuged and the supernatant was injected into HPLC. A column packed with octadecyl silicate and a mobile phase of 50 mM of potassium phosphate monobasic/acetonitrile (85/15) were used. The whole analyses and quantitative determination can be performed within 15 min for samples containing PhS and PhG in the worker's urine with a simple mobile phase. The accuracy and precision in the present methods by the use of automated HPLC were satisfactory.     

气相色谱法同时测定工作场所中异亚丙基丙酮和苯系物

目的:建立工作场所空气中异亚丙基丙酮、苯、甲苯、二甲苯的气相色谱同时测定方法。方法:工作场所空气用管采集,0.5%甲醇的二硫化碳溶液解吸,程序升温初始35℃保持7 min,以30℃/min升温至120℃保持5 min,载气流量1.0 ml/min,HP-5毛细管色谱柱分离,FID检测。结果:各组分离效果好,解吸效率分别为92.3%～98.6%,在线性范围内,浓度与峰面积呈良好线性(r=0.999),回收率分别为90.5%～97.6%,检出限分别0.3μg/ml～1.2μg/ml,相对标准偏差(RSD)均小于5.0%。结论:该方法简便、灵敏、准确。适用于三苯及异亚丙基丙酮混合污染的喷漆业、制鞋业等行业工作场所空气的检测。     

Simultaneous determination of urinary creatinine and metabolites of toluene,xylene, styrene,ethylbenzene and phenol by automated high performance liquid chromatography

Summary An attempt was made to establish a method for the direct determination of urinary concentrations of creatinine, hippuric acid, methylhippuric acid and mandelic acid by automated high performance liquid chromatography (HPLC). Urine was diluted with distilled water or mobile phase, then the mixture was centrifuged and the supernatant was injected into HPLC. A stainless-steel column packed with octadecyl silanized silicate was used, and the mobile phase was a solution of [20 mM potassium phosphate monobasic containing 3 mM sodium 1-decanesulfonate]/acetonitorile (85/15). Another HPLC method for the determination of urinary concentration of phenol, metabolites of benzene and/or phenol is also described. Phenyl sulfate and phenyl glucuronide in urine were hydrolyzed enzymatically into phenol. The hydrolyzed mixture was injected into HPLC with the ODS column. The mobile phase was a solution of [20 mM potassium phosphate monobasic containing 1 mM sodium 1-decanesulfonate]/acetonitorile (85/15). The ratio of hippuric acid (HA) concentration to creatinine concentration determined by the urine of students after physical exercise was similar to that before exercise. Moreover, the coefficient of correlation found between the toluene concentration in a workshop and the HA concentration in workers' urine, corrected for creatinine, was higher than that obtained between the toluene concentration and the uncorrected HA concentration. For assays on stored urine samples, urine was spotted on filter paper, dried and kept several weeks, and then MA, HA, o-MHA, m-MHA and creatinine in the filter paper were eluted with 50% methanol and their concentrations determined by HPLC.     

Excretion of unchanged volatile organic compounds (toluene,ethylbenzene, xylene and mesitylene) in urine as result of experimental human volunteer exposure

Objectives To investigate elimination of unchanged volatile organic compounds (VOC’s) through urine and the use of respective data for occupational exposure assessment, six volunteers were exposed under controlled conditions to toluene (TOL), ethylbenzene (EB), xylene (XYL) and mesitylene (MES) at concentrations ranging from 20 to 200 mg/m³. The study was to elicit the toxicokinetic data and compare the precision of VOC’s exposure assessment based on determining unchanged compounds in blood, urine and their metabolites in urine. Methods During and after exposure blood and urine samples were analysed by gas chromatography using the headspace and SPME headspace technique Results The kinetics of VOC’s elimination in urine complied with an open two-compartment model. The (half-time) T _1/2 values varied from 0.45 to 0.88 h for phase I and from 6.7 to 19.2 h for phase II. The precision of the method for unchanged VOC’s was similar to that based on unchanged compounds in blood and better than their main metabolites in urine. Conclusion The obtained result indicate that determining unchanged VOC’s in urine can be used as an exposure test even in the ranges of VOC’s in the air that are much lower than the current TWA for occupational exposure.     

住宅装修后不同时间室内空气中苯、甲苯和二甲苯的监测

目的 监测不同档次新装修住宅室内空气中苯、甲苯、二甲苯污染水平,探讨防止苯、甲苯、二甲苯污染的措施.方法 对30户不同档次新装修住宅室内空气中苯、甲苯、二甲苯浓度进行了为期1 a的追踪测定.结果 室内空气中苯、甲苯、二甲苯浓度各检测1800次,装修后明显升高,随着时间推移大体呈下降趋势,5个月后超标率明显降低;不同档次装修的住房,大约在1 a后都能降低到国家规定的标准以下.苯、甲苯、二甲苯浓度还受室内、装修档次的影响,装修后的前3个月,高、中、低档次超标率苯分别为44.0％、54.0％和21.0％,甲苯分别为32.0％、36.0％和28.0％,二甲苯分别为36.0％、43.3％％和32.0％.结论 住宅装修完工后要加强室内的通风,至少于装修5个月后再入住,才可减少苯、甲苯、二甲苯污染对人体健康造成的损害.     

Leukocyte agglutinins in workers exposed to benzene,toluene and xylene

Summary A leukoagglutination test and a cytotoxic test with leukocytes were performed on 76 workers exposed to occupational contact with benzene, toluene and xylene (52 men, 24 women); the possibility of contact with these substances was eliminated in 41 persons in the period directly preceding the examination, and blood samples were collected from 35 persons in the course of the exposure. In the first group the presence of leukocyte agglutinins for autologous leukocytes was found in only one person and in the second group in 10 persons. The increase of leukoagglutination titer of sera after their incubation with benzene, toluene or xylene was also demonstrated. This suggested the occurrence of allergic blood dyscrasia in some persons exposed to benzene and its homologues.     

Evaluation of potential toxicity from co-exposure to three CNS depressants (toluene, ethylbenzene, and xylene) under resting and working conditions using PBPK modeling

Under OSHA and American Conference of Governmental Industrial Hygienists (ACGIH) guidelines, the mixture formula (unity calculation) provides a method for evaluating exposures to mixtures of chemicals that cause similar toxicities. According to the formula, if exposures are reduced in proportion to the number of chemicals and their respective exposure limits, the overall exposure is acceptable. This approach assumes that responses are additive, which is not the case when pharmacokinetic interactions occur. To determine the validity of the additivity assumption, we performed unity calculations for a variety of exposures to toluene, ethylbenzene, and/or xylene using the concentration of each chemical in blood in the calculation instead of the inhaled concentration. The blood concentrations were predicted using a validated physiologically based pharmacokinetic (PBPK) model to allow exploration of a variety of exposure scenarios. In addition, the Occupational Safety and Health Administration and ACGIH occupational exposure limits were largely based on studies of humans or animals that were resting during exposure. The PBPK model was also used to determine the increased concentration of chemicals in the blood when employees were exercising or performing manual work. At rest, a modest overexposure occurs due to pharmacokinetic interactions when exposure is equal to levels where a unity calculation is 1.0 based on threshold limit values (TLVs). Under work load, however, internal exposure was 87%higher than provided by the TLVs. When exposures were controlled by a unity calculation based on permissible exposure limits (PELs), internal exposure was 2.9 and 4.6 times the exposures at the TLVs at rest and workload, respectively. If exposure was equal to PELs outright, internal exposure was 12.5 and 16 times the exposure at the TLVs at rest and workload, respectively. These analyses indicate the importance of (1) selecting appropriate exposure limits, (2) performing unity calculations, and (3) considering the effect of work load on internal doses, and they illustrate the utility of PBPK modeling in occupational health risk assessment.     

Association of short-term ambient air pollution concentrations and ventricular arrhythmias

The authors evaluated the association between ventricular arrhythmias detected by implantable cardioverter defibrillators and ambient air pollution concentrations in the hours immediately before the arrhythmia. Patients given implantable cardioverter defibrillators at the New England Medical Center in Boston, Massachusetts, between mid-1995 and 1999 who lived within 40 km of a central monitoring site (n = 203) were followed until July 2002. The authors used a case-crossover design to study the association between ambient air pollution and up to 798 confirmed ventricular arrhythmias among 84 subjects. The authors found that interquartile range increases in 24-hour moving average particulate matter less than 2.5 mum in aerodynamic diameter and ozone were associated with 19% and 21% increased risks of ventricular arrhythmia, respectively. For each, there was evidence of a linear exposure response, and the associations appeared independent. These associations were stronger than associations with mean concentrations on the same calendar day and previous calendar days. The authors did not find associations with pollutant concentrations less than 24 hours before the arrhythmia. Cases with a prior ventricular arrhythmia within 72 hours had greater risk associated with air pollutants than did cases without a recent arrhythmia. These results confirm previous findings and suggest that matching of pollution periods to arrhythmias is important in detecting such associations.     

BTEX air concentrations and self-reported common health problems in gasoline sellers from Cotonou,Benin

To examine the relation between BTEX exposure levels and common self-reported health problems in 140 gasoline sellers in Cotonou, Benin, a questionnaire documenting their socioeconomic status and their health problems was used, whereas 18 of them went through semi-directed qualitative individual interviews and 17 had air samples taken on their workplace for BTEX analysis. Median concentrations for BTEX were significantly lower on official (range of medians: 54–207?μg/m³, n?=?9) vs unofficial (148–1449?μg/m³, n?=?8) gasoline-selling sites (p?vs official selling sites (p?相似文献   

Method for simultaneous determination of six metabolites of toluene, xylene and ethylbenzene, and its application to exposure monitoring of workers in a printing factory with gravure machines

For the biological monitoring of exposure to solvent composed of toluene, xylene, and ethylbenzene used in a printing factory with gravure machines, we developed a HPLC method for the simultaneous determination of urinary metabolites of this solvent, i.e. hippuric acid, o-, m-, and p-methylhippuric acid, mandelic acid and phenylglyoxylic acid. Except for phenylglyoxylic acid, urinary concentrations of the metabolites determined by the present method correlated well with the air concentrations of the respective solvent components. Hence the present method is useful in monitoring solvent exposure. In 91 workers of the printing factory and 53 control subjects, we also determined the concentrations of some phenolic metabolites and confirmed that o-cresol is a useful indicator for monitoring toluene exposure.     

Serum immunoglobulin levels in workers exposed to benzene,toluene and xylene

Summary Immunoglobulin levels in the sera of 35 workers occupationally exposed to benzene, toluene and xylene were studied by means of a simple radial immunodiffusion. The immunoglobulin levels were compared with those of a control group of 42 healthy adults. A statistically significant decrease was observed in the IgG and IgA levels, accompanied by an increase in the IgM level. It is possible that this observation reflects a suppressive action of benzene on immunoglobulinproducing cells, resulting in the inhibition of DNA synthesis.     

Serum complement level in workers exposed to benzene,toluene and xylene

Summary The serum complement level was determined in 79 persons subject to occupational exposure to benzene, toluene and xylene. In 62 of them the complement level was lower than the mean value of the control group. The mean value of the exposed persons is also statistically significantly lower than that of the control group (p<0.01). These findings are consistent with previous data suggesting the involvement of immunologic factors in the pathologic mechanism of exposure to benzene and its homologues.