染土じん肺の本態とその予防に関する衛生学的研究

第3篇染土およびその代替品によるじん肺性病変に関する実験的研究

抄録

Farmers engaged in “tatami” producing process are exposed to “sendo” dusts. “Sendo” means dyeing materisl being used for the process of. “dorozome”. to keep rushes' and “tatami” products' color unfaded. It is clayey dust and contains 20-30% free silica.
1. “Sendo”
The experimental study on fibrogenesity to rat's lung by intratraheal infusion of 3.5% and 10% suspension of “sendo” dusts was made. The results are as follows.
Evident dust foci and slowly but steadily progressed collagenous fibrogenic reaction were observed histologically in the lung tissue of rats treated “sendo” at 3 to 6 month after infusion. This suggests that rush farmers' pneumoconiosis raise due to long-term inhalation of “sendo” dusts.
2. Substitute materials for “sendo”: eight trial productions.
The exploitation of substitute materials for “sendo” has been made. And eight kinds of trial productions, consisting of TiO₂, ZnO, MgO, CaCO₃ and some amount of “sendo”, were provided. These materials were examined fibrogenesity to lung tissue with comparison of “sendo” by same method of former experiment. The results are as follows.
These materisls showed less stronger fibrogenetic reaction to lung tissue than that of “sendo” histologically. And contents of hydroxyproline of lung tissue of rats were estimated 4.0-5.5mg per total dry weight of right lung at 6 month after infusion. On the contrally, 6.0-7.0mg were the controlled lungs treated by “sendo”, quartzsands and kaolin. But these materials contain some amount of “sendo” and/or TiO₂ which fibrogenesity to lung tissue has been already observed. So the further study were undertaken.
3. Substitute materials for “sendo”: three markettable goods.
Three kinds of new substitute materials for “sendo”, mainly consisting of ZnO+CaCO₃+BaSO₄ or MgO+CaCO₃, were provided for rush farmers. Contents of free silica of these new materials were 0.0-1.0%. And experimental study showed these materials relatively weak fibrogenesity to lung tissue than that of “sendo” histologically, and tissue hydroxyproline of right lungs were estimated 3.5-4.5mg. This suggests that these three kinds of new substitute materials for “sendo” were available for the dust control of rush labor.