Biotransformation and kinetics of excretion of ethyl tert-butyl ether in rats and humans.

Ethyl tert-butyl ether (ETBE) may be used in the future as an additive to gasoline to increase oxygen content and reduce tailpipe emissions of pollutants. Therefore, widespread human exposure may occur. To contribute to the characterization of potential adverse effects of ETBE, its biotransformation was compared in humans and rats after inhalation exposure. Human volunteers (3 males and 3 females) and rats (5 males and 5 females) were exposed to 4 (4.5+/-0.6) and 40 (40.6+/-3.0) ppm ETBE for 4 h in a dynamic exposure system. Urine samples from rats and humans were collected for 72 h at 6-h intervals, and blood samples were taken in regular intervals for 48 h. In urine, ETBE and the ETBE-metabolites tert-butanol (t-butanol), 2-methyl-1,2-propane diol, and 2-hydroxyisobutyrate were quantified; ETBE and t-butanol were determined in blood samples. After the end of the exposure period to inhalation of 40-ppm ETBE, blood concentrations of ETBE were found at 5.3+/-1.2 microM in rats and 12.1+/-4.0 microM in humans. The ETBE blood concentrations, after inhalation of 4-ppm ETBE, were 1.0+/-0.7 microM in rats and 1.3+/-0.7 microM in humans. ETBE was rapidly cleared from blood. After the end of the 40-ppm ETBE exposure period, the blood concentrations of t-butanol were 13.9+/-2.2 microM in humans and 21.7+/-4.9 microM in rats. After 4-ppm ETBE exposure, blood concentrations of t-butanol were 1.8+/-0.2 microM in humans and 5.7+/-0.8 microM in rats. t-Butanol was cleared from human blood with a half-life of 9.8+/-1.4 h in humans after 40-ppm ETBE exposure. In urine samples from controls and in samples collected from the volunteers and rats before the exposure, low concentrations of t-butanol, 2-methyl-1,2-propane diol, and 2-hydroxyisobutyrate were present. In the urine of both humans and rats exposed to ETBE, the concentrations of these compounds were significantly increased. 2-Hydroxy-isobutyrate was recovered in urine as the major excretory product formed from ETBE; t-butanol and 2-methyl-1,2-propane diol were minor metabolites. All metabolites of ETBE excreted with urine were rapidly eliminated in both species after the end of the ETBE exposure. Excretion half-lives for the different urinary metabolites of ETBE were between 10.2 and 28.3 h in humans and 2.6 and 4.7 h in rats. The obtained data indicate that ETBE biotransformation and excretion are similar for rats and humans, and that ETBE and its metabolites are rapidly excreted by both species. Between 41 and 53% of the ETBE retained after the end of the exposure was recovered as metabolites in the urine of both humans and rats.     

工艺条件对GOR-Q催化剂降低催化汽油烯烃含量的影响

在实验室小型固定流化床反应器上考察了工艺参数对国产 GOR- Q催化剂降低催化汽油烯烃的影响。结果表明 ,GOR- Q催化剂具有明显降低汽油烯烃的效果 ,低反应温度、低空速和高剂油比都将导致催化汽油烯烃含量降低 ;催化汽油烯烃的降低主要是通过小分子烯烃的降低来实现的     

Critical review of cancer epidemiology in petroleum industry employees, with a quantitative meta-analysis by cancer site

A critical review of close to 100 published and unpublished but otherwise available epidemiologic reports of petroleum industry employees from the United States, United Kingdom, Canada, Europe, Australia, and Japan was conducted. Analyses by duration of employment and latency are discussed, and summary standardized mortality ratios (SMRs) or meta-SMRs are developed for selected cancer sites. Findings indicate that the industry experienced a significantly lower cancer mortality than the general population for all cancer sites combined, digestive system, stomach, and lung. For the industry as a whole, SMRs similar to the general population were observed for skin, brain, pancreatic, prostatic, and kidney cancers. However, some data indicate that certain small groups within the industry might have elevated prostatic and kidney cancer risk. This review supports the conclusion that some refinery employees, particularly those employed before the 1940s, may have been at increased risk of leukemia. There is some indication that cancer of other lymphatic tissue may also be elevated. Unresolved issues affecting these conclusions are discussed, and specific directions for future research are offered.     

Adverse effects of gasoline on the skin of exposed workers

Gasoline is widely used as a solvent in industry. To study its adverse effects on the skin and to understand their mechanisms, a matched epidemiological study (1:1, 52 exposed workers and 52 control subjects) was developed. Information about general conditions, history of dermatosis, changes in skin after exposure to gasoline, etc., was obtained. Ceramide, fatty acid and cholesterol collected from the backs of the hands were analyzed by high‐performance thin‐layer chromatography (HPTLC), because stratum corneum lipids play a predominant rôle in maintaining the physiological function of skin. The results showed that prevalences of hyperkeratosis, dryness, onychosis and dermatitis were clearly higher in exposed workers than in the control group, prevalence ratios being 3.33 (p<0.05), 3.00 (p<0.001), 11.25 (p<0.001), 5.00 (p<0.001), respectively. Fissures and onychorrhexis were the common symptoms in exposed workers. The stratum corneum lipid levels of ceramide, fatty acid and cholesterol were significantly lower in the exposed group than in the control group (p<0.05). Findings indicated that prolonged or repeated contact with gasoline could cause fissuring of the skin and nail disorders, and that the mechanism was perhaps depletion of stratum corneum lipids.     

汽油尾气诱导的细胞毒性效应涉及氧化应激

目的探讨氧化应激在汽油尾气三相有机提取物(EGE)细胞毒效应中的作用。方法采用MTT比色试验检测汽油尾气对A549细胞的细胞毒性效应,同时用2’,7’-二氯双氢荧光素双乙酸酯法测定汽油尾气对细胞活性氧(ROS)生成的影响;此外,用不同浓度谷胱甘肽(GSH)预处理细胞2h后再观察汽油尾气细胞毒性效应的变化。结果当EGE浓度>3.9ml/ml时,细胞存活率均显著降低(P<0.05),并且具有良好的剂量-反应关系(r=-0.81,P<0.01)。当汽油尾气浓度为31.3ml/ml和62.3ml/ml时,A549细胞单位面积的荧光强度分别为(125.0±19.2)和(168.9±16.9),与对照组(8.5±1.4)比,细胞单位面积荧光强度显著增加(P<0.05)。采用0.5和1.0mmol/L谷胱甘肽预处理细胞后,处理组细胞存活率显著高于未处理的对照组(P<0.05)。结论氧化应激可能是汽油尾气细胞毒性的毒作用机制之一。     

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   

Controlled Ethyl tert-Butyl Ether (ETBE) Exposure of Male Volunteers: I. Toxicokinetics

Ethyl tert-butyl ether (ETBE) might replace methyl tert-butylether (MTBE), a widely used additive in unleaded gasoline. Theaim of this study was to evaluate uptake and disposition ofETBE, and eight healthy male volunteers were exposed to ETBEvapor (0, 5, 25, and 50 ppm) during 2 h of light physical exercise.ETBE and the proposed metabolites tert-butyl alcohol (TBA) andacetone were analyzed in exhaled air, blood, and urine. Comparedto a previous MTBE study (A. Nihlén et al., 1998b, Toxicol.Appl. Pharmacol. 148, 274–280) lower respiratory uptakeof ETBE (32–34%) was seen as well as a slightly higherrespiratory exhalation (45–50% of absorbed ETBE). Thekinetic profile of ETBE could be described by four phases inblood (average half-times of 2 min, 18 min, 1.7 h, and 28 h)and two phases in urine (8 min and 8.6 h). Postexposure half-timesof TBA in blood and urine were on average 12 and 8 h, respectively.The 48-h pulmonary excretion of TBA accounted for 1.4–3.8%of the absorbed ETBE, on an equimolar basis. Urinary excretionof ETBE and TBA was low, below 1% of the ETBE uptake, indicatingfurther metabolism of TBA or other routes of metabolism andelimination. The kinetics of ETBE and TBA were linear up to50 ppm. Based upon blood profile, levels in blood and urine,and kinetic profile we suggest that TBA is a more appropriatebiomarker for ETBE than the parent ether itself. The acetonelevel in blood was higher after ETBE exposures compared to controlexposure, and acetone is probably partly formed from ETBE.     

Genotoxic effects in workers exposed to low levels of benzene from gasoline

To study genotoxic effects of exposure to low levels of benzene, single-strand breaks (SSB) in DNA of leukocytes and urinary levels of the oxidative DNA adduct 8-hydroxydeoxyguanosine (80HdG) were determined in 33 men occupationally exposed to benzene from gasoline and in 33 controls. The average exposure to benzene over a shift was determined by personal air sampling in the breathing zone. The 8-hr time-weighted average exposure to benzene was 0.13 ppm (mean value, range 0.003–0.6 ppm). Exposed workers had a significant increase of SSB (p = 0.04) over the shift compared with controls. Storage time of the samples seemed to affect the results. An analysis of samples with the same storage time showed a nonsignificant increase among the workers compared with controls. Urinary 80HdG increased over the shift among the exposed workers but not among the controls. The highest values among the exposed workers were seen in late evening, with a slight decrease the next morning. Multiple linear analysis adjusting for smoking habits showed a significant association between the exposure level of benzene during the shift and the increase of 80HdG in the urine over the shift among exposed workers (p = 0.02). These findings indicate a genotoxic effect in humans of benzene at relatively low exposure levels, that is, about 0.1 ppm (0.3 mg/m³). © 1996 Wiley-Liss, Inc.