Brown S L
R2C2, Oakland, California 94605, USA.
Regul Toxicol Pharmacol. 1997 Jun;25(3):256-76. doi: 10.1006/rtph.1997.1104.
This paper presents information on the ways in which people can be exposed to methyl tert-butyl ether (MTBE) via air and water and on the distribution of doses that can result from those exposures. Data on concentrations of MTBE in air were complied for 15 different occupational, commuting, or residential exposure categories, and concentrations in potable water were complied from five states in the MTBE-using areas of the United States. Based on these concentrations and characteristics of the exposed populations, average daily and lifetime average doses were estimated. Both the concentration data and several of the population characteristics were estimated as distributions rather than as point values so that the numbers of people exposed at various levels could be estimated. Arithmetic mean occupational doses via air were in the range of 0.1 to 1.0 mg/kg-day, while doses from residential exposures, commuting, and refueling were in the range of 0.0004 to 0.006 mg/kg-day. Lifetime doses for workers were in the range 0.01 to 0.1 mg/kg-day. The cumulative dose distribution for the entire population of the MTBE-using regions of the United States was estimated by combining the distributions of doses and the numbers of people in each exposure category. In the MTBE-using areas, arithmetic mean doses via air were estimated to be 0.0053 and 0.00185 mg/kg-day for the chronic and lifetime cases, respectively. Approximately 98.5% of the population living in MTBE-using regions uses water with concentrations affected only by atmospheric deposition, if at all, and too low to be detected with current methods (< 2 micrograms/liter). The remaining population uses water with an estimated geometric mean concentration of 0.36 microgram/liter, an arithmetic mean concentration of 49 micrograms/l, and a 95th percentile concentration of 64 micrograms/liter. Doses via ingestion, inhalation, and dermal absorption were included. The estimated arithmetic mean dose for the population exposed via water was 1.4 x 10(-3) mg/kg-day.
本文介绍了人们通过空气和水接触甲基叔丁基醚（MTBE）的途径，以及这些接触可能导致的剂量分布情况。收集了15种不同职业、通勤或居住接触类别的空气中MTBE浓度数据，以及美国MTBE使用地区五个州的饮用水中MTBE浓度数据。根据这些浓度和接触人群的特征，估算了平均每日剂量和终生平均剂量。浓度数据和一些人群特征均以分布形式而非单点值进行估算，以便能够估算不同暴露水平下的接触人数。通过空气的职业算术平均剂量范围为0.1至1.0毫克/千克·天，而居住接触、通勤和加油的剂量范围为0.0004至0.006毫克/千克·天。工人的终生剂量范围为0.01至0.1毫克/千克·天。通过结合各暴露类别中的剂量分布和人数，估算了美国MTBE使用地区整个人口的累积剂量分布。在MTBE使用地区，慢性和终生情况下通过空气的算术平均剂量分别估计为0.0053和0.00185毫克/千克·天。生活在MTBE使用地区的人口中，约98.5%的人使用的水中MTBE浓度即使受大气沉降影响，也低至当前方法无法检测到（<2微克/升）。其余人口使用的水中MTBE估计几何平均浓度为0.36微克/升，算术平均浓度为49微克/升，第95百分位数浓度为64微克/升。计算了经口摄入、吸入和皮肤吸收的剂量。通过水接触的人群的估计算术平均剂量为1.4×10⁻³毫克/千克·天。
