Document g56EOB6vx241KBJQ2BD1qgXL

2 INDUSTRIAL HYGIENE AND OCCUPATIONAL MEDICINE Attention is directed to the mineral brucite, Mg0.H,O, which is often found in the same formations with serpentine and chrysotile and may be fibrous in structure. Except for the manufacture of magnesium, brucite has no commercial value at present because its fibers are not sufficiently flexible to be used in textiles, but they are capable of repeated longitudinal subdivision. Unlike other asbestiform minerals, brucite is not a silicate, and for this reason it has been a valuable tool in an experimental evaluation of the action of fibrous minerals on lung tissue. EXPERIMENTAL ASBESTOSIS For many years studies1 have been carried on at the Saranac Laboratory in an investigation of the cause, nature and development of asbestosis. The present paper is devoted to experimental asbestosis, Fig. 1.--Human asbestosis (P-36-144). The photomicrograph reveals-a bronchi ole (right center) with a smooth muscle bundle at its inferior margin and with an extensive zone of collagen deposition largely obliterating the surrounding alveolar structure. The black foci are macrophages containing incidental pigment. Asbestosis bodies are present but arc not apparent at this magnification (X 200). and in it are described the experiments made on animals with various kinds of asbestos dust. Another report, to be prepared and issued at a future date, will be concerned with human asbestosis and will cover the health aspects of workers who have been exposed to asbestos dust in an industrial environment. Although in man asbestosis is a chronic disease with diffuse pulmo nary fibrosis which requires years to develop, it is possible to reproduce 1. (o) Gardner, L. U., and Cummings, D. E.: Studies on Experimental Pneumokoniosis: VI. Inhalation of Asbestos Dust; Its Effect upon Primary Tuberculous Infection, J. Indust. Hyg. 13:65 and 97, 1931. (6) Gardner, L, U.: Chrysotile Asbestos- as an Indicator of Subtile Differences in Animal Tissues, Am. Rey. Tuberc. 45:762, 1942.