Document KJQZvy0wgrXDbjNYNQ2JyxZnN

FILE NAME: Norton (NORT) DATE: 1935 DOC#: NORT002 DOCUMENT DESCRIPTION: Book Excerpt from Industrial Medicine - Asbestos & Asbestosis OCEAN STATE HEALTH RES T EL N o . 14,90 42 No .002 .LIMIT AN STATE HEALTH RES TEL No . Feb / , INDUSTRIAL MEDICINE in silicosis. E a rly asbestosis must be differenti ated from acute emphysema. T reatment of Silicosis and A sbestosis The treatment of both of these conditions is preventive and symptomatic. Early removal of the affected worker from the inciting cause of his disease is imperative. When the disease has progressed beyond the early stages, removal is useless. The fibrosis continues to build up whether the worker is exposed or not and eventually leads to incapacity. For this reason unless the silicotic worker has signs of respiratory infection, tubercular or otherwise, it is inadvisable to remove him from his work after nodular fibrosis is present. The man w ill gain nothing and w ill lose several additional years of productive work at tasks with which he is fam iliar and at which his earning capacity is highest. The same may be applied to asbes tosis. In the recent report of the Special Industrial Disease Commission of Massachusetts it was fflN STfiTE HEALTH RES TEL Feb 14,90 15=42 N o .002 P .04 124 INDUSTRIAL MEDICINE recommended that " no finding of physical un fitness shall be made except in evidence of active pulmonary tuberculosis." In the Ficher Clinic, held in connection with the Picher mines, workers are not barred from employment unless they are infected. PN1 T h ere ar in which conccntrai dustry is i ill effects now to tal with some abling fibr Carbon ulate impu air as unbi dust and j black smok pared with concentrati H4 INDUSTRIAL MEDICINE it was noted that foundry workers were particu larly susceptible to pneumonia, " about one fourth of all foundry men being found to suc cumb to this disease." Tuberculosis may result from the activation of an old quiescent process, or it may be an in fection superimposed upon the silicotic fibrosis. .Thus according to Kettle [98] " harmful dusts if inhaled into the lungs may excite to activity a latent tuberculosis infection, they may exagger ate an active tuberculosis lesion or a coincident infection; and they may render the lung less able to cope with a superimposed infection." The pathology resembles that of fibroid phthisis, the middle and basal areas of the lungs are more frequently involved and tubercular broncho-pneumonia more common. Cavity for mation may occur and the whole picture re semble that of an advanced case of pulmonary tuberculosis [28]. Tubercle bacilli are usually not plentiful but may be found in the centers of areas of necrosis (Fig. 22). A t any time there may, through a breaking down of a necrotic area containing tubercle bacilli, be a rapid spread to INDUSTRIAL MEDICINE 115 other parts o f the lung. The course of silicosis with a secondary tuberculosis is, however, usu ally slow, and " without the usual symptoms of intoxication and may be carried for years with out serious impairment of working capacity" [ r 47]. Respiratory infections other than tuberculosis are frequent. " On the Rand pneumonia is the most common cause of disability and death among native laborers." Proske and Sayers [13 9 ] have confirmed Cummings' discovery of fuso-spirochetal organisms as a cause of infec tion among miners in Picher. O f the pneumo nias, broncho-pneumonia is the more frequent, lobar-pneumonia being relatively rare. A sbestos and A sbestosis The commercial article known as asbestos is not a distinct mineral but is a name applied to any mineral which can be separated readily into more or less flexible fibers. The most important variety is that obtained from chrysotile (H *M gs SiaO*) which is mined extensively in Canada, j* Sufficient exposure to dust of asbestos in any ii6 INDUSTRIAL MEDICINE stage of its processing may cause asbestosis. It should be noted that there is no free silica in asbestos although the total silica in pure chrysotiie is 44.x per cent Symptoms and P hysical Signs of A sbestosis The symptoms and physical signs of un complicated asbestosis are suggested by the pathology. A fter 5 to 10 years' exposure, the patient usually complains o f slight dyspnea and a cough which is dry and annoying. The ex pectoration if present is scanty. A s the condition advances the dyspnea becomes more marked and may appear on the slightest exertion. With the dyspnea are pains in the chest. There is rapid loss of weight going on to emaciation. Cyanosis is frequently present and the complexion is " earthy." Inspection show's an emphysematous type of chest with poor nutrition. Expansion is limited frequently to less than 1 inch. The per cussion note all over the chest is one of dull tympany reaching dullness at the bases. On aus- v r r , ' *? -.?v & Fic. 22. Uarre granite cutter. T w o isolated silicotic nodules. Cellular connective tissue borders and hyaline fibrous centers. Thickened interlobular septum extending upward to the left of the right nodule. Note dilated lymph vessels in septum. (Courtesy of D r (j<trdener and U. S. Publir Wraith <SVrfiiVe [ i -|-51*) QD' A r.ntVON Z P : ST 0 6 ` t?T q^d ON 131 S3d H llb B H 3 1 b lS t/ 144 INDUSTRIAL MEDICINE which the engineer welcomes as an objective of cleanliness for which to strive. Some of these figures are founded upon reliable data and some are frankly estimates. Legge and Duckering [10 4 ], [46] suggested 0.5 mg. per cu.m. for lead dust which Russell and his colleagues [146] lowered to 0 .15 mg. for litharge indicating that this figure might be scaled up or down with changes in the solubility of the lead compound in serum. The South A frican authorities, for their high quartz rock in the Witwatersrand gold mines, have gradually arrived at a figure of about 1 mg. per cu.m, and silicosis, under their conditions, has not been eliminated (although greatly re duced). Higgins, Lanza, Laney and R ice [8 1] suggested 10 mgs. per cu.m, for the high quartz rock of the Jop lin , Missouri, zinc and lead dis trict. In both of these examples the standards suggested are both practicable and attainable. Russell et al [14 5 ] in their granite study in Barre, Vermont, suggested 9 to 20 million parti cles per cubic foot by the impinger sampling INDUSTRIAL MEDICINE J 45 technic and light field counting. Here the dust contained about 35 per cent quartz. In sand stone working, where there is a high percentage of silicates, Badham, in Australia [5] advocated 200 particles per cubic centimeter by Owens' jet dust counter, but hinted that 100 would be better. In Great Britain, perhaps wisely, no figures for permissible dustiness in connection with silicosis have been suggested. In their cement dust study Thompson and his associates [16 4 ] investigated one of the most harmless inorganic dusts of modern industry. The effects upon the chests of workers with abundant dust exposure were in no way com parable to the chests of the granite workers de- ^ picted by Russell. Nonetheless, Thompson ad- vocated 10 to 20 million particles per cubic foot as compared with 9 to 20 million for granite. In the case of asbestos dust no figures have as yet been suggested but on the basis of abun dant experience M cConnell [t 16] of the M etro politan L ife Insurance prefers to see the dust count below 5 million and welcomes still 146 INDUSTRIAL MEDICINE lower figures. Merewether [12 0 ] gives figures on asbestos dust concentrations but no indica tion of permissible dustiness. In studying metal fume fever caused by breathing freshly formed zinc oxide (Fig. 10), Drinker, Thomson, and Finn [4 3] found that concentrations of 14 mgs. of zinc per cu.m. for 8 hour exposures or 45 mgs. for short exposure could be tolerated without causing the " shakes" to the average worker. D rinker believed that figures could easily be obtained for other metal lic fumes but the required experiments have never been done. Prodan [13 8 ] found that cad mium oxide fume, which is close to zinc oxide metallurgically, was fa r too toxic to permit breathing measurable amounts. T o insure the avoidance of trouble from chromic acid mist Bloomfield and Blum [ 15 ] suggest that continuous d aily exposures be kept below 1 mg. per cubic meter and show in their report that this figure is readily attainable by proper transverse ventilation. Cummings [32] sees no need to require the manufacturer of materials with w ell established INDUSTRIAL MEDICINE 147 harmless effects to maintain air as clean as that demanded in granite cutting. However, there is no longer any excuse for excessive dustiness in any process--it merely represents slovenly practice. A few years ago it was not uncommon to see workmen employed m an atmosphere so thick with dust that a 50 watt lamp was obscured at a distance of to feet. In a recent lawsuit a witness testified that he had to sweep up every hour because if he waited longer it was necessary to use a shovel I Industrial physicians and en gineers have seen these conditions but they can not defend them. The only justifiable conclusion to be drawn from such apparent inconsistencies is that gen erally we lack data for defining rigidly permis sible dustiness. The application of medical and engineering knowledge and common sense to dust control is highly commendable but the point has not been reached where a manufacturer can be told with certainty that his plant w ill have no silicosis, no asbestosis, or no lead poisoning if he keeps dustiness down to some definite figure. He can be told only that the maintenance of certain i 48 industrial medicine degrees oi air cleanliness represents the best pres cnt practice. T h e question is asked frequently whether to million quart? particles per cubic foot breathed fo r 8 hours is equivalent to 70 m illion for 1 hour plus 1 m illion for 7 hours, the total amount entering the respiratory system in both cases be ing 80 million. On this point M avrogordato [ 1 1 3 ] in discussing his " dust floods" says: " Lesions o f silicosis in a m ild degree can be produced in an animal by 30 hours' exposure to intense dust clouds, and one is inclined to sus pect that it is intermittent exposure to relatively dense clouds that is the deciding factor in pro- TABLE 6 A vekace D ust Count in C ert a in D u st y T rades. {n Jvitry Slate finishing m ills Floortnen ................................................ L o ad ers .................................................. D isc cru sh er o p e r a t o r s ...................... T a lc mining Jack h a m cr d rille rs ............................. M uckers .................................................. T a l c finishing mills C rush ers and cy lin d erm e tt............... P a c k e r s .................................................... ................. ................. ................. ................. ................. ............................. D u st CQXKt m cti.'o v r 0/ p oftitk* prr cmbU / o i Wait 15 9 8 .0 I276.O 3*2.8 2159.8 44-3 14-0 5<>.i s IN D U STRIA L M ED IC IN E I49 Industry rwXtS*ti*f*mmf+t rtrytrla fw -csMr J*l of r Marble carvers.................................................. 19.1 Marble cu tters..................................................... 32.8 Granite quarrying Leyner drillers ............................................. <444 Jadham tr drillers ............................ U 2.1 Plug drillers ................................................. 36.9 Cement mill, average of all operations.............. 26.0 Granite cutting Hand pneumatic tool operatives.................. 59.2 Machine pneumatic tool operatives............ 35,9 Attendant la b o r............................................. 17*0 Anthracite coal mining . Mining and miners* helpers.......................... 31.5 Attendant la b o r..........................................................3 1.1 Bituminous coal mailing Coal cutters and coal loaders...................... IX2.3 Attendant la b o r........................................ 3.9 Silverware manufacturing Dusty processes........................................ 5-2 N on-dusty p rocess................................ 1-7 Municipal dust (street cleaners) Congested district.................................... 4.1 Residential district...................................... 1-8 Cotton industry Carding room ............................................... 8.6 Weaving and spinning room .................. 4-5 during the disease in susceptible human sub jects." A ll medical experience is in accordance with Mavrogordato's statement and after all, it is only physiological commonsense-- a sub threshold stimulus for a long time produces no reaction whereas a relatively brief super- 150 INDUSTRIAL MEDICINE threshold stimulus may cause a reaction. It is not enough to find that the average dust concentra tion is below a desired figure: occasional ex posure to excessive dustiness should be avoided. I ndustrial Dust Concentrations Granting the advisability of maintaining the concentrations indicated, it is just as well to know something of the concentrations one actu ally finds in sampling. In this country Bloom field [14 ] of the U . S. Public Health Service, and Fehnel [ 117 ] of the Metropolitan L ife In surance Company, have assembled and per sonally determined dustiness in a large number of industries. Some of Bloomfield's data are given in Table 6. Harrington [72], [73} gives figures of dustiness in mines and the early min ing investigations by Higgins et al [8 1] are still useful. Chapter I X LEAD AND METAL FUM E FEVER L ead L ead in small quantities is being ingested daily by most people. Kehoe [95] has shown that even in isolated non-industrial communities normal individuals excrete a certain amount of lead daily. Workers in lead or where the process involves the use of lead are exposed to abnormal amounts of the metal and may suffer from lead poisoning. While in the case of exposure to tetraethyl lead, absorption is through the skin [70], in the major ity of cases lead is inspired as a dust or fume [ 7 1 ] . Although a small amount of lead may be taken in by mouth from the worker's unwashed fingers, the amount in most cases is too small to be of importance [7 1].