Document jBzKKvK63VaDZGx9MeQxLGq82

350 Twenty-third Annual Safety Cunyress--National Safety Council The Dust Hazards in Industry By DR. R. R. SAYERS Medical Officer in Charge, Office of Industrial Hygiene Sanitation, United States Public Health Service, Washington, D. C. Tlte s]cakcr >aid in |art: Realizing tlte iinituriattcc oi the dust problem in industry, the L nited States Public Health Service in cou]H.Tatiiin with the Bureau of Mines began its first study oi the health oi workers in dusty trades in 191-4, in the mines of Joplin. Missouri: and later, in 1923. the Public Health Service inaugurated a series of dust studies. These later studies were all conducted in the same manner in order to permit as detailed a comparison! as iiossihle lictwcvn the different investigations. Briefly, these methods of study may Ik* divided as follows: (1) examination to determine the general physical condition tit the workers under observation: (2) special physical examination t> determine the prevalence t*f specific diseases of the respiratory system and the lung pathology resulting from exposure to the particular dust Itazard; (3) record <*i tlie nature anil severity of the disabling illnesses: (4) analysis and tlctailed study of the occupatimial environment: (5) occupational mortality statistics relating to the S|ccific-dust; and (0) autopsies. The first six intensive investigatHms carried out by the Service dealt with the health of workers exposed to dusts in a cement plant, granite cutting industry, anthracite and Iritumiuous cal mining, silverware manufacturing plant, cotton doth manufacturing, and in municipal street sweeping. Brief studies were later conducted hi certain slate, granite. utarMc and talc quarries. while more recently a rather extensive study oi the health of anthracite coal miners was completed. These six dust studies showed tliat tin.* workers in tlte granite cutting plants who were cxjnised to the highest dust concentrations were found to suffer from an execs* oi_ pulmonary tulierculosis after 15 years or more of exi>osurc and developed silicosis Irotu 2 to 10 years. In the group exposed to a lesser amount of dust, silicosis developed only after ]irolonged exposure, with no excess oi tultcrculosis. It was fiumd tltat a close relatumship existed between tlie degree of dust exposure and the extent and severity of the pulnvuiary damage. Anthracite coal miners suffered from dysjmnea and other signs of imcumoconiosis and eX|cricnced a high rate of respiratory sickness: in addition, an excessive mortality from influenzapneumonia and iiossihly tulxrctilosis was found. Bituminous coal miners cxjterienccd a generalized fibrosis of the lungs and an excess mortality from influenza and imeumonia. Cement workers showed some signs of early pneumoconiosis with an excess oi diseases of tin* ujijkt respiratory tract. On the other Inrnt workers in the cotton cloth and silverware manufacturing plants and niunici|)al street sweepers were ncgati\*e for respiratory conditions and other illnesses when cumitarcd with the general industrial population. Rock DriUin/. For five years, the United States Bureau of Mines studied lead and zinc miners in the Tri-State District. Oklahoma. The ore here is high in free silica. Oi the 7.722 men examined, a group of 1.M7. or 21.3 ]>er cent, was definitely diagnosed as having silicosis. not including those diaguoseil as having tuficrculosis. All the men diagnoses! as having first-stage silicosis had worked an average of 13 years, hut those men starting in tlte mines after 40 years of age worked ati average of only 8 years. Tlte work of n>clc drilling in subway and tunnel construction in Xew York City is in some rcsjtects similar to tltat of some of the activities in the hard rock mines, at least in so far as the manner in which dust is evolved, the type of dust and tlie resultant hazard. Recently the result of a study of rock drillers, blasters and excavators was reported by the Xew York TuIktcuIosis and Health Association. An examination oi 208 rock drillers, blasters and excavators showed tliat 118. or 57 jkt cent of the men had silicosis in various stages of progression. Tlte exposure of most of these men < 75 per cent 1 had Itcen for 20 years or more. Sandblasting. Xo study of the health of sandblasters has Itccn reported in the United States: however, a study oi the dust censure of sandblasters was recently completed by the United States Public Health Service in cooperation with the Quarry Section 351 Xational Safetv Council. This investigation indicated that, judged hv the nature of the dust and degree of the vx|osiirc. a real hazard exists in this occujmtuni. This study also brought out the fact that it is possible to conduct sandblasting with safety, provided (iropcrly designed and well maintained equipment is used. Diatamaceous Silica Workers, Most of the data on silicosis have Itcen gathered from studies made Imth in industry and experimentally on dusts containing free silica in the form of quartz. Such studies have Item made in the granite^ industry, pottcrv trades, liard rock drilling, etc. There arc other free silica minerals in existence that are not crystalline m nature but of an amorplKtus cotnjwisition. In Santa Barbara County. California, there exists the largest and purest diatomaewus silica deposit in the world. This substance consists of alxurt 85 per cent free silica. Recently an examination was made of 1118 workers selected among those employed less than 1 year. 1 to 2 years. 2 to 5 years, and more than 5 years. All oi the workers were Mexican laltorcr* and the examinations consisted of x-ray determinations, social and medical histories, and clinical examinations of the diesis. Dust determinations were also made hut these were not reported. The outstanding feature revealed by the examination was tlie splcndidphysical condition of the men. Eighty-four per cent of the workers were reported in excellent. physical condition. It was found that GO men showed signs of early pneumoconiosis: 15 were in the moderately advanced stage and fi in the advanced stage. _ This latter finding was among workers with a history of exposure of more than 5 years. Dust Hazard in the Granite Quarry Industry. It is a common Mief that granite quarrying is not so dangerous an industry as granite cutting in enclosed sheds: quarry work is done outdoors and hence may i*rt lie attended with verjmuch dust exposure. However, certain quarry o|K*ratious reipiire the use of pneumatic tools, which are usually associated with the formation of considerable quantities of dust. It was thought that a study made in a representative granite quarry might east some light on ottr problem. Accordingly, a sltxly of a clintcoradiographic nature of r3 quarriers was made and fccupational dust exposures were also obtained. The dust determinations show tliat nearly 38 per cent of tbc^ worker* (drillers) were exposed to many times the amount of dust considered safe at the present time. Drillers were the only arsons showing pathologic lung changes. Half of these workers with an cx|>osurc of 5 to 19 years liad silicosis, ami 4 of the 5 men with more than 20 years of such trade life showed this condition. This studv suggests that quarry' drillers may cx|cricncc as high a <k*ntli rate from pulmonary tuberculosis as do tmcumntic-tool workers in granite cutting sheds. lifted of fnhated J/erWr Dust. The pulmonary fihrotic elumges tlue to tlie inhalation oi marble dust appear to lc slight in comparison with those caused hv stone dust containing a high percentage of silica in the form of quartz. A recent studv made hv us among marble workers showed that although marble tins!, when inhaled in concentrations averaging about 25 million particles per cubic font of air. produced a mild bilateral, linear fibrosis in a certain immltcr of the Rll men examined, no serious lung changes were noted and there was no disability due In the dust, even after many years of cx|to*urc fniorc titan 4fl years in some cases!. The marble dust under consideration consisted of 98 per cent calcitc and 2 |tcr cent dnlcmitc. with no silica present. Dust Hazard in Abrasive Industry. Artificial abrasives arc widely used in industrv and for this reason the effect of the inhalation of dusts produced in the manufacture or preparation of tliesc products is ti great imitnrlancc. In 1925. 1929 and again in 1931. Dr. Dark of the Xorton Company at Worcester. Mass., made investigations o| workers exposed to aluminium oxide ami silicon carbide dust produced in tlie manufacture of grinding wheels, which showed tliat during a i>criod of 13 vears there were proportionately twice as many eases of pulmonary tuber culosis * among those working in the altrasive dust departments as in dqiartmcnts where no abrasive dust occurred. In 1931. Kessler, of Xew Jersey, reputed tlte occurrence oi over 100 cases oi alleged silicosis in tlie abrasive powder industry, in which the dust consisted of 99 per cent free silica. Exposure to Silicate Dust. It has been the belief tliat tlie inhalation of dusts composer! of silicates (combined silica!, in comparison with silics* (free silica in the form of quartz!, was innocuous. Of recent years many investigators have become cognizant of the hazards of silicate dust exposure. Asbestosis. a fibrosis