Amandus H E, Wheeler R, Jankovic J, Tucker J
Am J Ind Med. 1987;11(1):1-14. doi: 10.1002/ajim.4700110102.
The vermiculite ore and concentrate of a mine and mill near Libby, Montana, was found to be contaminated with fibrous tremolite-actinolite. Of 599 fibers (length greater than 5 microns and width greater than 0.45 micron) counted in eight airborne membrane filter samples, 96% had an aspect ratio greater than 10 and 16% had an aspect ratio greater than 50. Additionally, 73% of the fibers were longer than 10 microns, 36% were longer than 20 microns, and 10% were longer than 40 microns. Estimates of exposure before 1964 in the dry mill were 168 fibers/cc for working areas, 182 fibers/cc for sweepers, 88 fibers/cc for skipping, and 13 fibers/cc for the quality control laboratory. In 1964-1971, exposure estimates for these areas were 33, 36, 17, and 3 fibers/cc, respectively. Estimates of exposures in the mine before 1971 ranged from 9-23 fibers/cc for drillers and were less than 2 fibers/cc for nondrilling jobs. All 8-hr TWA job exposure estimates decreased from 1972-1976, and from 1977-1982 were less than 1 fiber/cc.
蒙大拿州利比附近一座矿山和选矿厂的蛭石矿石及精矿被发现受到纤维状透闪石-阳起石的污染。在八个空气传播膜滤器样本中计数的599根纤维（长度大于5微米且宽度大于0.45微米）中，96%的纤维长径比大于10，16%的纤维长径比大于50。此外，73%的纤维长度超过10微米，36%的纤维长度超过20微米，10%的纤维长度超过40微米。1964年之前，干选厂工作区域的暴露估计值为168根纤维/立方厘米，清扫工为182根纤维/立方厘米，跳汰工为88根纤维/立方厘米，质量控制实验室为13根纤维/立方厘米。1964 - 1971年，这些区域的暴露估计值分别为33、36、17和3根纤维/立方厘米。1971年之前矿山中钻探工的暴露估计值为9 - 23根纤维/立方厘米，非钻探工作的暴露估计值小于2根纤维/立方厘米。所有8小时时间加权平均工作暴露估计值在1972 - 1976年下降，1977 - 1982年小于1根纤维/立方厘米。
