Lindstrom A B, Pleil J D
National Exposure Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, USA.
J Air Waste Manag Assoc. 1996 Jul;46:676-82. doi: 10.1080/10473289.1996.10467502.
Methyl tertiary butyl ether (MTBE) is added to gasoline (15% by volume) in many areas of the U.S. to help control carbon monoxide emissions from motor vehicles. In this study we present a sampling and analytical methodology that can be used to assess consumers' exposures to MTBE that may result from routine vehicle refueling operations. The method is based on the collection of alveolar breath samples using evacuated one-liter stainless steel canisters and analysis using a gas chromatograph-mass spectrometer equipped with a patented "valveless" cryogenic preconcentrator. To demonstrate the utility of this approach, a series of breath samples was collected from two individuals (the person pumping the fuel and a nearby observer) immediately before and for 64 min after a vehicle was refueled with premium grade gasoline. Results demonstrate low levels of MTBE in both subjects' breaths before refueling, and levels that increased by a factor of 35 to 100 after the exposure. Breath elimination models fitted to the post exposure measurements indicate that the half-life of MTBE in the first physiological compartment was between 1.3 and 2.9 min. Analysis of the resulting models suggests that breath elimination of MTBE during the 64 min monitoring period was approximately 115 micrograms for the refueling subject while it was only 30 micrograms for the nearby observer. This analysis also shows that the post exposure breath elimination of other gasoline constituents was consistent with previously published observations. These results demonstrate that this new methodology can be used effectively in studies designed to assess exposures to MTBE. The method can be used to objectively demonstrate recent exposures, the relative magnitude of an exposure, and the approximate duration of the resulting bloodborne dose. Once a blood/breath partition coefficient for MTBE has been firmly established, the bloodborne concentration of the absorbed material can be determined using these techniques as well.
在美国许多地区，甲基叔丁基醚（MTBE）被添加到汽油中（体积比为15%），以帮助控制机动车的一氧化碳排放。在本研究中，我们提出了一种采样和分析方法，可用于评估消费者因日常车辆加油操作而接触MTBE的情况。该方法基于使用抽空的一升不锈钢罐收集肺泡呼吸样本，并使用配备专利“无阀”低温预浓缩器的气相色谱-质谱仪进行分析。为了证明这种方法的实用性，在一辆汽车用优质汽油加油之前及加油后64分钟，从两个人（加油者和附近的观察者）身上采集了一系列呼吸样本。结果表明，加油前两名受试者呼吸中的MTBE水平较低，接触后水平增加了35至100倍。根据接触后测量结果拟合的呼吸消除模型表明，MTBE在第一个生理隔室中的半衰期在1.3至2.9分钟之间。对所得模型的分析表明，在64分钟的监测期内，加油者呼吸中MTBE的消除量约为115微克，而附近观察者仅为30微克。该分析还表明，接触后其他汽油成分的呼吸消除情况与先前发表的观察结果一致。这些结果表明，这种新方法可有效地用于旨在评估MTBE接触情况的研究。该方法可用于客观地证明近期接触情况、接触的相对程度以及由此产生的血源剂量的大致持续时间。一旦MTBE的血/气分配系数确定，也可使用这些技术确定吸收物质的血源浓度。
