Document KJOGO2g7j9mZaROgr6ewRZwnx

;? 1 ty*. ""<5 5 1 .t l j ASHESTOS DUST DEPOSITION AND RETENTION IN RATS . f J. C. Wegner and J. W. Skidmore ' U>!<Ue-ai Research Council, PneumoeoniiuiU Beetareh Unit, Uandovffh Hotpila], Prnarth, Glamorpan. Great Britain Introduction t. In previous animal dueling experiments histological studies have estab lished differences In the ffbrogenic properties of various type* of asbestos (Warner, 1963 and elsewhere in this monograph!. Experiences with hu man cases of pleural mesothelioma have indicated that these have occurred mninly in association with (he Inhalation of crocidolilc. but in a current research project the intrapleural inoculation of a variety of dusts -- chrys- otile. crocidolite, amosite, and silica -- into rets haa induced pleural mesotheliomas. The amount of dust inoculated, 20 mg., appeared by his tological examination to be greatly in excess of the amount found in the majority of human cases of pleural mesothelioma. In sn attempt to clarify the position a aeries of dusting experiments was planned, and for this it was desirable to produce sn experimental method by which ctjual amounts of any asbestos dust could be deposited in the. lungs of rats by an inhalation method. Additionally it was necessary to ascertain whether the various types of asbestos were retained in the lungs to the #y. unit extent and had a similar histological distribution. With these objec- - lives s method was devised for producing the dust clouds and a preliminary S etperiment cairied out . ^ ' r-MetBOM ^fifiy-seven male and W fenile standard Witter Albtnorale:'Wtrt 'avBv^ : ' $sp!$ir the experlmenCand tiveae weV m>dowdyVffb<atei'dti'a>ir(atlitical `basis'^ptb 6. gToups. Tour Jdfi''i*t4h.e1 g--rlm^.WchtnbtLtttlnt&.toilto'te'andJ ..ViSiteS fetoslStsts were exposed to airborne etbuda df ehrysotHe,' erbddolite, amo^'"'^ ' *> t .site, or powdered glaas; the first group''waa not exposed to dut and tlmV fwta staking uplhts group wens used Weontrol*. The powdered glass waa iatl.uded as an Inert nonflbrous duit for compsrative purpo**a.;:- .;1;^. -. -,'^hodtslsb ehrysotlle and South African erocidoUt* and ainoalte were' '`Chuined'fn the most finely ground commercial grade, and eachwaa further., utid (n a mierohammer mjlt'to break doyrh'i SCF-FA-0032 PP.ODUCF.n "V ertpn