Abstract
The present report is based on the experiments in which rabbits have been used in order to see the possible cause of the atrophic changes of the nasal mucous membrane observed in miners and reported in the previous report. The results are summarized as follows: 1. By inhalation of dust of quartz or propylite 1 to 1.5 hours a day and 6 days a week for three years, remarkable changes appeared in the mucous membrane of the upper respiratory tract of rabbits. 2. The more the silica content of the dust, the more marked these atrophic changes. 3. By inhalation of dust of silicic sand for six months signs of the atrophic changes appeared already, while in the case of dust of deposited copper under refinery or of charcoal for the same length of period such signs could not be observed. 4. It is concluded that inhalation of the silicic dust develops the atrophic changes of the mucous membrane of the human upper respiratory tract. And, it is considered that such changes promote the development of silicotic changes, decreasing the dust-filtering function of the nasal cavity.
