Yu C P, Zhang L, Oberdörster G, Mast R W, Glass L R, Utell M J
State University of New York at Buffalo, Amherst 14260.
Environ Res. 1994 May;65(2):243-53. doi: 10.1006/enrs.1994.1035.
Chronic exposure and postexposure experiments have been recently performed in rats to evaluate the biological responses of inhaled refractory ceramic fibers (RCF) at different concentration levels. The lung burden data in the accessory lobe of the rat lung were collected during and after different exposure and postexposure periods. The size distribution of retained fibers in the lung at different time points was also measured. We used these data to develop a mathematical model of fiber clearance from the rat lung. It was found that the clearance rate did not depend significantly upon fiber size but there was a clear dependence on lung burden. As lung burden increased, the clearance rate was found to decrease. An empirical equation was derived for the clearance rate as a function of lung burden. At low burdens, rats had a retention half-time of about 126 days for RCF compared to a typical half-time of about 60 days for insoluble nonfibrous particles.
最近在大鼠身上进行了慢性暴露和暴露后实验，以评估不同浓度水平下吸入难熔陶瓷纤维（RCF）的生物学反应。在不同的暴露和暴露后时期以及之后，收集了大鼠肺副叶中的肺负荷数据。还测量了不同时间点肺中留存纤维的尺寸分布。我们利用这些数据建立了大鼠肺中纤维清除的数学模型。结果发现，清除率并不显著取决于纤维尺寸，但明显依赖于肺负荷。随着肺负荷增加，清除率降低。推导了清除率作为肺负荷函数的经验方程。在低负荷下，大鼠对RCF的留存半衰期约为126天，而不溶性非纤维颗粒的典型半衰期约为60天。
