Middleton A P, Beckett S T, Davis J M
Inhaled Part. 1975 Sep;4 Pt 1:247-58.
Rats have been dosed over a 6-week period with U.I.C.C. standard reference samples of amosite, crocidolite and chrysotile A, each at three concentrations: 1,5 and 10 mg/m3. Mass concentrations in the exposure chambers were monitored daily. Because the M.R.E. gravimetric sampler was found to undersample some of these dusts at high concentrations, a sampler with a vertical elutriator was developed. Data on other physical parameters of the dust clouds were also obtained and it was found that the fibre number (greater than 5 micron in length) vs. mass correlation varied markedly between asbestos varieties. After dusting, the rats were sacrificed in five batches over a period of 4 months. The lungs of some animals were retained for pathological examination. This did not reveal any fibrosis although large numbers of fibres were visible, mostly within alveolar macrophages. The remaining lungs were analysed for their asbestos contents by a method based upon infrared spectrophotometry. The clearance data confirm earlier published reports that for rats dosed at similar mass concentrations of chrysotile and amphibole, those dosed with chrysotile retain considerably less dust in their lungs. The data also suggest that the retention and clearance of amphibole abestos may be dose related. Some mathematical treatment of the clearance data has been undertaken.
在为期6周的时间里，给大鼠吸入国际抗癌联盟（U.I.C.C.）的铁石棉、青石棉和温石棉A标准参考样品，每种样品设置三个浓度：1毫克/立方米、5毫克/立方米和10毫克/立方米。每天监测暴露舱内的质量浓度。由于发现M.R.E.重量采样器在高浓度下对其中一些粉尘采样不足，因此开发了一种带有垂直淘析器的采样器。还获得了粉尘云其他物理参数的数据，发现纤维数量（长度大于5微米）与质量的相关性在不同石棉品种之间有显著差异。给药后，在4个月的时间里分五批处死大鼠。保留了一些动物的肺用于病理检查。尽管可见大量纤维，主要在肺泡巨噬细胞内，但未发现任何纤维化。其余的肺通过基于红外分光光度法的方法分析其石棉含量。清除数据证实了早期发表的报告，即对于以相似质量浓度给予温石棉和闪石的大鼠，给予温石棉的大鼠肺中保留的粉尘要少得多。数据还表明，闪石石棉的保留和清除可能与剂量有关。已对清除数据进行了一些数学处理。
