Document MoMVEvXq9jYLL5KEBOqJqR3m7

366 0. A. SANDEB ________~_-v---------------------------------------------- Figure 3. Composite diagram (modified from Miller11) of the primary lob'uljp'lyiuph'' system, indicating the primary distributions or accumulation points for dust thistlS^ir predominant phases of pneumoconiosis: b.r., respiratory bronchiole; dal., alvepH atria; sal., sacculi alveolare; a.p., alveoli opening into respiratory bronchioles and a'ivl in close relation with the origins of peribronchial and perivascular lymphatics>;i^fcr pulmonary artery, accompanying the air passages; V., branch of pulmonary yeip3r|f|| A,septum; pleura; PJ3., peribronchial lymphatics; P.V., perivascular lymphati||HT other dotted areas, lymphoid deposits. (By previous permission of Dr. W. Si Miiieft The lymphatic-system consists of vessels that cany fluid simi'lSar''tilBm| plasma and nodules composed largely of protective and phagocytjb2|l| lymphatic vessels an^ lymphoid .tissue areimportant in eonnedaoBtM^j^f 6. Phag^i^JIn,tlie alyeolar spaces there are large cells capabje!:o|||ngg foreign material and having the power of independent motion. A larglfpfr -;these-agieboid"-forms"at)pear-rwhere.veE^fQr.eigmmuttar.iftfc..ftbf;isrgth^s^ ingesting the exogenous particles, some of these cells pass into the bl#q|$$pf finally lodge in the spleen and liver or move elsewhere in the lung tiSsu|||| jority, however, make their way to the lymph vessels and eventually-to tions of lymph tissue, where they lodge. This resting place may be anyw^r Tfes, mt/ PULMONARY DUST DISEASES 367 lagocytes migrate peripherally to the pleura and others centrally to !p;'lymph tissue the foreign material may be absorbed, may remain jpj Or may, by some chemical reaction, initiate pathological changes rmation of silicotic nodules. Viy*iP! Factors of Importance in Injury by Dust ig^o/ air inhaled. Just as we are interested in the amounts of dust j'air, so are we also interested in the amount of air inhaled by men s-v-T* f%c.pnditions. This has been discussed in Chapter VI. wfev frSntiehinittiioi n. Before we can arrive at a logical basis for determining *S|ible concentrations, it is necessary to know what proportion of '^plained. Since most dust-collecting apparatus imposes considerable fheVpassage of air from the lungs, satisfactory results were not ob it studies until Baumberger12 used an electrostatic precipitator with aoiigh to reduce the resistance to a negligible factor. His studies on llhyielded results considerably higher than those obtained later by Ij|rinker, Thomson, and Finn,14 and by Brown.18 Baumberger found > Iger, cent retention of smoke. Sayers, working with tetraethyl lead in 'Sarying from 0.35 to 10.4 mg. per cubic meter of air, found that only * aipjetained and attributed this limited retention to the small particle gpWzSW/owji agtudies gave rather conclusive results, showing that the percentage ||sely proportional to the minute volume of air breathed and to the ^^jyhereas-it-is-directly-proportionahto-the-particulata size,, density uwm?s.aaftteu?en.r..d.eHdeinfoauinr,datnhdatthreeteexntteionnt to which was not the dust affected is wetted while by volume per passrespi- japacity, or relative humidity of inspired air. Wi V. Dust Causing Pulmonary Fibrosis A. SILICOSIS 1. History re^ners Prevent the breathing of ^^TAUj^^iumbirger, J. Pharmacol., 21, 47 (1923). S. Bur. Mines Rcpt. Invest. No. 2661, 1924. Thomson, and J. L. Finn, J. Jnd, Byg., 10, 13 (1928). ^i.iM9tjJ>linm5;vSecundus, Naluralis kistoria, Bk. II. Trans, by K. C. Bailey under the SII Blder\Hkriy?8'Chapter on Chemical Subjects, Pt. 1. Longmans; Green, New York, "Geh^giua^AgricoIa, De re metaUica, Bk. I. Trans, from 1st Latin ed. of 1556 by H. (3- Vinil T^sfi^Hoover. Mining & Sci. Press, San Francisco, 1912. nAft T.. '