Non-fibrous zeolite induced experimental pneumoconiosis in rats.

A study was made on the pulmonary pathological reactions after intratracheal introduction of non-fibrous zeolite into CFY rats in long-term sequential investigations (1st week; 1st, 3rd, 6th months and 1st year). After treatment at the end of the 1st week non-specific confluating bronchopneumonia followed by a storage type reaction developed at the end of the 1st month. In the later periods in addition to storage character mild pulmonary fibrosis has been observed. At the end of the 1st year, transmission electron microscopy and X-ray microanalysis verified that aluminium and silicon ratio in zeolite storaged in the macrophages of the lungs was the same as found in natural zeolite (1:6). In the lungs of 3 animals atypical hyperplasia developed; therefore an in vivo study of the carcinogenic effect of non-fibrous zeolite seemed justified.