Document a4pV204z9LygMx8KvDw8wxVKY

& renders tho flb*ir inoopa^lu of producing fibroolo. It thus appears that thliae coating llai a protaeoctilveo imechealmn. This thought wma ojeprosjsed u#. by polotker aa oqrly aa 1934^^*'. THK'OUT 0? I II R I T A H T ACTIOH Two hypotheses haro been proposed to explain tho tissue irritation and reaction caused by a aba ato flberoi the chemical and tho moohanloel. In the ohoaloel theory, wtiich la based upon experience with quirts, It la asrumed that the aobeatoe nlaorala dlsaolvs In tha body flulda and ttit la this process their basee are leaehed away to laawo alllea In a fob capable of Irritating tissues, According to thla hypothoala aebestoate would ba merely an Indirect aillooei a, Several facta aalce tho chemical theory untenable: Intratrachoal InjectionjI of bruolte fibers, which had ft a allied eentent of only 0,90 per oont, oaused a typical fibre ale lgo that produced by tho asbestos olneralag freo-elllea particles incroeoe In po tency as tha particle also bocoaes lose, but aabeotos fibers shorter than about 10 to 20 ttlorons oro relatlToly innoauoue: aluminum hydroxide neu tralises tho Irritating effect of quarts but not of aoboatoeg serpontlao ho a the oomo chemical ocBpocltlon ae long-fiber ohryeotlle but it produeed only an inert type of tlaeuo reaction! there la a wido range In tho chemical coapooitlon of tho minerals vhloh do eauso asbestos!a (table 19). In view of thin ovldonco'it toeras sore likely that eebeotoela is oauoed by an' unuoual ftcchutleal irritation from long aaboetoa fibers, thli f(n Bolntker, w.i (Jber die Aebottoalokorporchen. Benerkungon su der Arbeit won Oogor. Virchows Arch. f. path. Anat. 293 627, 1934. i. -40- V> % T