Document G6vEOyjDvrvGkJd07D0aMBQdq

* IXDUSTRtAL HYC1EXE ASD OCCVI'ATtOSAL MEDICISE of various animaJs (guinea pig, rabbit, rat. mouse, cat. dug. chicken and even tadpole 1 eventually \*.fil produce siiicotic nodules but at dinerer.t rates. Similar introduction v.. lone fiber a-l>e*to> has resulted in a fibrous reaction in the lung and. to a lesser extent, in the peritoneum bufnet m other organs-oi the gutncamgTTttfralitTit. thecaand the white ral. In our experience the lungs of the dog and the white mouse tailed to respond with fibrosis, although Schuster* lias reported such change* in a dog that lived in an asbesios-iabricatmg plant. This variation in species and in organ susceptibility is yet to be accounted for 1; it is presumed that in the susceptible animals the greater rcactmu of the lung to asbestos, far exceeding the reaction of other organ tissues, is due principally to the greater mobility of the lung. Previa.c* Cuaxactoistics or Asar.sms Experience has demonstrated that most of the nonfihrous du*t particles iuiialcd into the lungs of uun aiul animal arc 10 microns or leas TajLX l.--Reaetiou u Long Fiber Chrytonle in f.unnr ri Man ard Other Sfeeirt oi .! mmi Siwm X u.................... Ooa t<r.............. IMII..................... Ct......................... . Well* rt_.............. fblKmow........... 0"f....................... llodrol Cimaf laktlillot IiJ4ltM u4 lalwwt Iikildioa iiri ignnuo tilnUUm iw lai(oia lahtuuon >l injmlca loKaltUoa Lajeetica Flt.ro.i* * 4* 1-*. 0 a AiMiun IMIm Sgairasa Scdmi'ir iunraiH Rr* *o<i ttrpirtl Rrt mr. < m;i>w*l Vrr rr>Kg.-r n-< .Irr*l No a* Tn' *f::ill> ) lo * * itlif to in* i**err* ol ilw rrarlHm. in maximum dimension. Larger particles apparcmlv do not gain access to the lungs, because, first, large panicles settle in air 5o rapidly that few remain suspended in the atmosphere breathed and. sei nnd. large particles are more effectively removed hv the protective mccnanisms ot the upper respiratory tract. In the case of fibrous materials these factor.? have less influence and fillers 100 and even 2(0 micron* in length have been found in the terminal air maces of human iungs. In *rrnil labora tory animals exposed to asbestos dust the maximum length of fiber found in the lung rarely exceeds 60 microns. A large proportion of nonfihrous particulate dust inhaled into the lung is found in the terminal air spaces ( aiveoiar ducts, atre.im*. alveoli) in all parts of the organ: in contrast, ir.naied ashestos fiber* are first discovered in the respiratory bronchioles. These small passages are immediately distal to bronchicies fined b> ciliated epithelium.* Their 2. Schuster. .V. H.: Pulmonary Aibestosis in a Dog, J. paih. & Bact. 34 (?t. 21:751. 1921. J. Voruald, A. ].: Variations in Incis '`jal Suscetaubilitv io Ir.dusirial Dusts Inhated tr.to the Lanes. Am. Rev. Tabere. 62: ilC) 12. 1950. * Miller. W. S.: The Lung. Sprirgheid. 111. Charles C Thomas. Publisher. 1927 oi** nar aiv. cha_ oi : rI is: v per. ob.<< quar (rad one rnont inhaJ docs ditty: expo oodn peri short proct progr Tt body" golden or cur The l mierrx- If. tein ar observi subcue abunda in thei fibers o S. C T uherdc oer and ( 6l L; J. A_ M Asbestost Asbestos Gloyne.*-*