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1 10 Vt` v-r *1 1 y W . ., <&V*r. -7 7U)Strac?R--1972 Conference JJ s?? -S ft/it'. p j ABSTRACTS 161. THE EFFECTS OF MASS LOADING OF DUST ON BRONCHIAL CLEARANCE / C. PHILLIPS, M. LIPPMANN, PfiD., and R. E. ALBERT, M .o /ln stitute of ` Environmental Medicine, New York University Medical Comer. New York, New York Studies are being conducted to determine the effects of the mass loading of inert dusts on particle deposition and clearance. The effect of large amounts of inert dust on alveolar clearance, following intratracheal injection j^ther than by inhalation, has been studied by others. These studies showed th^increasing the lung burden of - particles increased the amount of alveolar clearance up to a point; beyond which ' ' clearance was reduced as the lungs became congested. In-vivo inhalation tests are being conductor using high concentrations of preclassified coal dust. The test subjects are miniatute'oonkeys whose bronchial clearance patterns were previously established. The cofrl dust aerosol has a CMD - 2.90mm and a iTg -- 1.30. as determined by optical sizing techniques. The retentions o f"m T c tagged ferric oxide particles in Jffe deep lungs, main bronchi and upper thorax regions are measured simultancously'to determine the clearance waves in additional control tests, and in tests immcdjnely following coal dust exposures. The coal dust aerosoLfS generated with a Wright Dust Feed, which requires the use of dry compressed aiarTo eliminate the effects of dry air inhalation on the clearance pattern, a specipi humidifier was developed. The dust laden air stream leaves the humidifier at^a dry bulb temperature of 38C and a 95% relative humidity, and the donkey brodthes from this 30 Ipm air stream via nasal catheters. The breathing rate is monitorpo during the periods of dust inhalation. Th^dTfects of high concentrations of coal dust on tagged particle clearance will be described and discussed. 162. BIOLOGIC DIFFERENCES IN RESPONSE TO LONG AND SHORT ASBESTOS FIBERS w T e . SMITH, M.D.," D. D. HUBERT, and M. S. BADOLLET, FlorhamMadison Campus, Farleigh Dickinson University, Madison, New Jersey. Six preparations of chrysolite were tested by intrapleural injection of hamsters with 25 mg sample suspended in 0.5 ml saline. Each preparation was tested in a group of 50 ^"hamsters maintained for periods up to 700 days. Extensive pleural adhesions developed in hamsters in 3 groups treated with chrysolite preparations having mean fiber lengths of 32.5 to 38.9 microns as measured by optical ' microscopy and 5.3 to 6,9 microns as measured by electron microscopy. In these 3 groups, intrathoracic tumors with characteristics of pleural mesotheliomas developed in 8, 9 and I0 hamsters, respectively. - Three other groups of hamsters were treated with preparations of these chrysolites after further milling that reduced mean fiber lengths to 0.37 to 0.86 microns as measured by electron microscopy. Only rare fibers exceeded 5 microns in length. These 3 preparations induced relatively thin pleural adhesions. No mesotheliomas occurred in hamsters treated with them. The findings afford evidence that fibrogenic and carcinogenic actions of chrysolite are related to physical properties of the fibers. L; 67 l t WIT----------- Z6i 9 S 0 3 0 Hearing Clerk Food and Drug Administration, Room 6 - 8 6 5600 Fishers Lane________ Rockville, Maryland 20852 uSA ry y