Document n9DOOOarKLxgXLd31G6vv1jx1

'V AfETY COUNCIL .A SERVICE ;. '' m DUSTS, FUMES, AND MISTS IN INDUSTRY Copies of this data sheet will he available for purchase within 30 days. Subscribers tc the Council's data sheet maintenance service will receive a copy in the next quarterly nwiliny. Introduction 1. Industrial dusts, mists, and fumes, their hazards and their am- trol. arc discussed in this data sheet.* The general principles presented can he applied to evaluate most in dustrial situations involving these air contaminants and *.o determine the need for controls. Tais data sheet is intended to guide employers, plant safety engineers, personnel man agers. anil supervisors. 2. A plant manager who believes that he has a toxic or irritating dust problem should consult a competent industrial hygienist. Such help may be obtained from his own company, insurance carrier, private consul tants. or state health or labor agency. 3. To protect the health of em ployees who work where a dust, fume, or mist created by a manufac turing process is released into the at mosphere. a control program may be required. In such a case, three steps mast be taken: a. The properties ol the specific vUi*t. fume, or mist ;nnl its possible physiological elleel' on employee* must be ascertained. I Ills ilala sheet cover, toxic anil mmlaiini; air eonl.iiiiin.iMis e:ieoun:eie! in in.liistry. It Jiv* not tnelni'e a Mi*siissi'M: nt' tile explosive propeile* ol *mh .m binne p.nlienl.ite matte:. This doto sheet is one of a series published by the National Safety Council, reflecting experience from many scurces. Not every accept able sefety procedure in this field is necessarily included. This data sheet should not be canfused with American Safety Stand ards. federal lows, insurance re quirements, stale lows, rules, reg ulations or municipal ordinances. b. Tlte particular exposure iiuisl lv evaluated by dust count* or by chemical analyse"* ol air sample*, ami a *tep-by-*tep analy*i* ol the v'petation* imi*l he made to liiul the area* where employee* are ex pired to lia/arvliut* amounts ol the material. The operational anal ysis also should dcteiminc how the dust, tunic, or mi*l i* dispersed. e. Appropriate methiHl* of control mu*l be provided where indicated. The type and extent ol control* will depend upon the physical. ehemie.il. and toxic properties ot the dtM. iiimc. or mist, the evalua tion made ot the exposure, and the opei.tii.'n that disperse* the con taminant. the extensive controls needed tor lead ovule dust, lor exafip'e. would not be needed lor luuc'icnc dust, since much greater ijuantilie* ol limestone dn*t can be t.'ler.il.-vl -l. l-.vccpt fur the 'kin disease*, most occupationa I vliscascs arc ac quired by inhalation of material. I.ung tissue is by lar the most cllicicnt hTcdium the body possesses for ab sorbing materials. In addition, the surface area of This lung tissue aver ages 55 square meters or about 5 Ml square feet. 5. Cctlain dusts that reach the lungs can pass directly into the blood stream and be absorbed over a long period of time. Others nitty slay in the lungs and set up local irritant or dam aging action. f. Toxic and irritant dusts can also be ingested in amounts that tray cause trouble. If toxic dust swal lowed with food or saliva is not sol uble in body fluids, it is elimina'.cd directly through the intestinal tract. Toxic materials that tire readily sol uble in IhhIv fluid* can he absorbed in the digestive system and picked up by the b!iod. 7. A third way in which toxic and irritant substances may enter the system is skin absorption. Many or ganic-compound*. such as T NT', cy anides. and mo*; aromatic amines, amides, and phenol*, can produce systemic poisoning by direct contact with t!ie skin. Contact ol tovie .tin! irritant dust* with the 'kin also may result in *kin irritation. X. As compared to inhal.it on. iii nniimiam i<ih now ever. jiii nige'tioii and 'Kin c*itiicT nfet>r rGniivelv'hiinVr mipor-' lance in industiral ix'i'oiiing iii'ol:ir .i' ilii'is. fume'. :iiu! mi^i^ arc con cerned. with tals. .Dus; niav be tornjed and., dispersed when solij materials are reduced to small si/es in processes 'licit a grinding, crushing, blasting, shaking, and drilling. In these proc 5(1 m.ill.ion parcels' per cubic, fivit of air tmppel i. resulting Ironi 1 cubic eentimeier of material reduced to particles I cubic micron in si/e. will occupy an air space of 2lU'("> esses. ihe^mechanieal .action .of. the -- Origir* end Properties of' ' grinding or shaking device supplies Particulate Matter a source of energy to disperse the cubic feet,.... .............. - I N. liven smaller amounts of toxic ilti'ts. fume', anil mi'ts. will make a I lie Just normally present in dust formed I Figure I I. workroom atmosphere ha/ardou' the atmosphere has n beneficial 12. When a solid such a' a ntetal For example, the threshold limit cllcct in screening mil some of ihe is heated to a temperature high value for lead, as adopted bv the I harmful rays ol the miii. Inhalation of enough volatilize it. the volalil- American Conference of Govern < inis iliisi rn;iy hoi lv harmful Ivenuse lized matter later condenses in cooler mental Industrial Hygienists, is n.2 eillier llie dti't may lv m>nto\ie or air to form a itiin,- (Figure 2). The milligram per cubic meter of air body mechanisms capture. renio\e solid particles that make up a fume ting eu mi. which is (MKHHKK12 ;nul eliminate or isolate llie small are extremely line, usually less than ounce per cubic loot. Tlierelore. amounis of ilust [rapped in die lungs. <1.5 micron .in si/e. In some.eases, the- the dispersion-of onlv o (5t)2 ounce Air pollution. i.alioaelive fallout, hoi material react' with the air to of letid will be enough to give tile pollens, anil similar conditions may torni an oxide. F.xamplc' are lead threshold limit value ol " 2 mg ett m have an aiKerse elleet on some indi\iilnals. Also, when llie air breathed coni.mi-, excessive amounis of dust, oxide fume from smelting and iron ovide fume from tire welding. Also, a fume can be formed when a material of dust or fume in tin air space o! 1(1.00(1 cubic leet (2S0 cubic me ters). The concentrations that may llie body has dillietilly in handling the load and dust may remain in the such tis magnesium metal is burned or when welding or gas cutting is be present in. the workroom without harm to health are dilferom lor differ limes. done on galxnni/cil metal. ent siihstanees. Sources III. The lerm <///'/ as used in in dustry is generally applied to airhomc solid particles that ranee in si/e from I). I .micron io .25 .microns, lone micron I lU.iKKI centimeter I 25.000 inch). Process ilusis below 0.5 micron in si/c arc rare. Dusts above 5 microns in si/e usually will tiiM stay air-borne lone enough io present an inhalation problem. II. l)U't may enter the air from various source'. Il may lv dispersed when a dusty material is handled, such as when lend o\idc is Jumped into a mixer or a product i' dusted IA ifiiu is formed w hen a finely divided liquid is suspended in air. An example is the oil mist pro duced during cutting and grinding operations. . 1-: Siniiir may be formed by the incomplete combustion of organic materials. Smoke generally contains droplets .i' well j' dry particle'. Tobacco, for instance, proiluees a wet smoke composed ol minute tarry droplets. I he *i/c ol the particle' contained in tobacco smoke t' about H.25 mieton. 15. Radioactive ilii't may be ili'- perseil in the same ways as other in dustrial ilust'. Radium, thorium, am! 1'T A person with normal eye sight can detect dust particles as small as 50 microti' in diameter. Smaller air-borne particles can lv delected individually by .llie linked eye., only when 'iron: light is rellected from them. Dust of respirable si/e I below III microns) cannot lv seen without the aid of a microscope. 2't. Most industrial dusts consist of particles that vary widely in si/e. with the small particles greatly out numbering the large ones. Conse quently. with lew exceptions, when ilust is noticeable in the air around an operation, probably more invissible dii'l particles than visible one' oilier radioactive elements are pres are present. ent in extremely minute amounts in the atmosphere. Separation in air-borne dust 21. Dus! in the air may or may Magnitude of particles not have the same composition :i' !<'. When a solid i' broken into it' parent material. I lie determining finely divided particle', it' surface area i' increased many times, l or ex factors are the particle si/e and density of eaelt component in the ample. 1 cubic eentimeier tO.ttM original mixture, anil the harilne" cubic inch i ot quart/ in the lorn* " a ol the materials (hard materials will cube when crushed into I-micron rc'l'l the pulverizing action ot a cube' will give In'- t | .hiin.mm., mechanical dev ice. i nun.unit or one trillion i particles with a total 'Urtacc area ol <' square 22. I or example, loumlry mold ing sand contain' a large percentage meters I'l.vim square inches t. as ol Ire', silica i quail/i with a lower compared with < square centimeters percentage ol clavs. Mos; ol the clays (H'liii -on.ire inch) to: the original consist ol line panicles t.'iat can be Foi^ti 1 lu* 1 ouoi?* y sorsri *\ n'ort r*n# ** duiif o* tndmfjs 7h** *< *i<ic: cube. I~. When a solid is Ivok.n into .ur-hoine. but nto; o: tile quart/ particle' are too targe to be air- Uf'irn* 0^ i > Fii*n i'iii" \hiiin Oltl ijwl.'in *** j,, ii<v*i<l. s ov S. v **> Kor>tf stc^"> ,lxo ** (?s aiety ilivided particle'. the v.'lume Vsiipted bv the n.a i' also at e: e.i'si! 'ce.i'.i'e e! the void- 'vrv.;v*' boine. I he au-borne ..hi':, there- lore, -i' compared tv .vigrrvl lower percentage of free silica. . . 23- DtisT particles eirc; *f course:;' attracted by gravity. Their settling rttic through still air will vary with their si/c. density, and shape. NTicroscbpicalK small particles settle out r more vlowlv than -Ltrger part icles be cause of tlicir relatively minor densi ty and because of their be ins in fluenced . by Brownian movement. Mineral particles larger than 10 mi crons will settle out relatively fast. The estimated settling rates for silica dusts in still air are striven in Table I. TABLE I. SETTLING RATES FOR SILICA DUSTS Size in Microns 0.25 0.50 1.00 2.00 5.00 . Time to Fall 1 Foot (minutes) " 590.0 ' 137.0 54.0 14.5 2.5 24. ' Most tif the particles in air borne industrial dusts are small. Be cause or air currents, the line parti cles in dust clouds at an operation will remain suspended in the work room air for relatively long periods of time. The smaller dust particles, moreover, will travel farther away from their point of origin than will the larger particles so that the far ther dust is from its source, the greater the percentage of small par ticles -t contains. Inhalation of Dusts, Fumes, and Mists 25. With the exception of such librous materials as asbestos, dust particles must usually be smaller than 5 microns in order to enter the alveoli or inner recesses of the lungs. Al though a few particles up to It) microns in si/e may enter the lungs occasionally, nearly all the larger particles are trapped in the nasal passages, throat, larynx, trachea, and bronchi, from which they are expec torated or swallowed into the diges tive tract. 2b. When larger 'articles of cer tain toxic dusts are trapped in the upper respiratory passages, they can be absorbed by the body 'luids in the nasal pas'iie- and in the dtec'.ivv tract belore they .are elimi- ^ it: ted. Hence the linn! toxic'`ilTeets ' of larger du-l particles may be de layed. The larger partvles of irri tant dusts can cause immediate elfeets in the upper respiratory system. . s 27.-K:igueed 'pollen! which "var ies from IS to 25 microns in diameter can cause hay fever from its action in the upper respiratory system. This type of dust and other allergenic . types, as well as bacterial' and irritant dusts, can cause difficulty even ir. the larger air-borne sizes. 2X. When dust-laden air is in haled, same of the larger particles are trapped by the hairs in the nose. Figure 2. Mtol volotilittd by the heo< of **! trig later condentet to lc>n o fum*. On ?h Other 'Jus; particles are removed from the air as it passes over the moist mucous membranes of the nose, throat, and other portions of the b*nch*weldtng installation. Igmes ore ten** ot their point origin by o properly Wkci> local exhaust installation. Cou*t<ny Ammct Fowndrynen's Society! uptvr respiratory system. 2V. The bronchi and other re spiratory passages are covered \vith a large number of tiny, hairlike cilia or microscopic whiplashes, which aid in the removal of dust of ashe'tcs worker' at autopsy. . typical iVhrosis caused by nsN.-sti is produced by libers ranging :roi 2l> to 50 micron' in length, but ona few microti' w ide. trapped on these moist surfaces. The ciiia. all bending in one direction, make a fast stroke toward the mouth and. a slower return stroke. -Tlris action tends to push mucous and deposited dust upward to the mouth so that the particles can be ex pectorated or swallowed. Physiological effects 33. The physiological reaction caused by the inhalation of. -ait borne particulate matter will var with cilTcrcnt types, of dusts, fume.and mists. The reactions include a. Thv cardiopulmonary reaetio which consist' ol the pni-imn>ci Retention of dust 30. Many studies have been made in an clfor; to determine the amount of dust that is retained in the lungs, but there is no simple answer to this question. It has been shown that the size of the dust particles, the nio*cs. such as wV/ruwi anil <.'/>!> unit. In certain cases, specific tv pl ot lung pathology result, and th heart may he alfeeted (eor pul monale I when the tibrosis is ad vanceil. In other eases, there i mainly just an accumulation ol . relatively inert dit'l in the lung' rate of respiration, the density of the dust in the air. the ellicicncy of h. I he systemic reactions which ar caused by toxic dusts ol such ele the dtist-eatehing mechanism, and nunis as lead, manganese, cad probably many other factors are in volved. miimi. and mercury, by their com pounds, and by certain organit compounds. Sizes of particles inhaled e. Metal tunic lever which result- 3!. Although an occasional dust particle of larger si/e will enter the lungs, particles le" than 3 microns in diameter are the most likely to do o and thus have the greatest oppo*tunity to cause a physiological re action. In silicotic lungs, for example. dut particles under 3 microns great.y outnumber larger ones, and many particles are less than I micron. 32. In the ease of very line tibioii' ashesfo* dust, an evecplicit oeeur-> in the si/e of particles in haled Many liber'up t, 11u micron' from the inhalation of finely diiided and freshly generated lume o zinc or possibly ol magnesium o of their oxides. 'I hi' i' a traii'ieiv condition. d. Allergic and -.en'ili/ation reaction' si tineh may be eaii'i-d by irhalation of. or skin contact with. 'iieb. material' ;i' organic dti'i' trom Hour, grain', and 'omc wood*, and dusts ol .1 lew organic and inor ganic chemicals. e. Itaetvri.il and tiiiigti' nite.Iioii' which occur trom inliala!ii:i ot dii'ls containing acti'-C orcani'iii' Subvfcincc TABLE tl._S6l6CJEp.. INpUSTRrAC;MINERAL'.DUSTS . . '' . . Description ond Uses . :- * - \. * Threshold L;mut in Million Particles . per Cubic Foot of Air* , ....... - _ .CmtALllN-fS-:SHIO............. S*0 , including microcrystcHine forms .................. Chalcedony t>,r A heat-resisronr, chemically inert form of microcrystolline quartz. A decorative . material. Rore in' industry. A microcrystaDire form of silico. An impure form of flint used in abrasives. Colculole from formulo: * 250 *, SiO - 5 OistobolitC A crystalline form of free silico. extremely hord ond inert chemically; very resistant to heat. Ouertz in refroctory bricks end amorphous silico in diotomoceous earth ore ol'ered to cristoboJite when exposed to high temperatures fcol* . . cinedk Cristobolite is extensively osej in precision catting by the hot vox process, demot laboratory work, and certain specialty ceramics. F It'll A microcrystolline form of native quartz, more opaque and gronular than chalcedony. Used as on obrcsWe ond in ceromics. 5 Jospt'f i Ouorli A microcrystolline impure form of silico similar to chert. Used for decorative purposes. Rare in industry. .- Vitreous. hard chemically resiston? free siUcc. the most common form in noture. The main constituent in sandstone, igneous rocks, end common sands. Triiiymite Vitreous, colorless form of free silico. Formed when quorz is heated to 870 C '1,598 ? , Tripoli f Rottemfone't A porous, siliceous rock, resulting from the decomposition of chert or siliceous limestone. Used os a base in soap and scouring powders, in metal polishing, -as a filtering agent; and in wood and paint fillers. A cryptocrystolline form of free silica. . -- Oiotomoceous earth Silica qcI AMORPHOUS free silica Noncrysfollinv A soft, gritty amorphous siWco composed of minute siliceous skeletons of small oquotic plants. Used in filtration and decoiorizafion of licuids, insulation, filler in dynamite, wa*. textiles, plastics, point, ond rubber. Calcined ond flux-ccil* cined diatomoceous north contains ooorM<'oble amounts of cristobalite. and dust levels should be the same os for cristobalite. A regenerotivt* absorbent consisting o* the amorphous sil-.ca manufactured by the action of HCI on sodium silicate. Hord. glossy. quort?-lik#> in appearance. Used in dehydrating and in drying ond as a cotclvsf carrier. ' AmorpSorui 20 mppcf Colcined :. oio formulo 250 % SiO 5 20 mppcf Asbestos Clnyc Feldspar SILICATES Compounds mad** up of silicon, oyg*n, end one cr more metols with or without hyd'ogen. These dusts coute nonsp^cWe dust reactions, but generally do not interfere with pulmonary 'unction or result in ciscibilify. A hydrated magnesium silicate in *brous form. The fibers are believed to be the more hazardous compom-n* of asbestos dust. A great variety of oluminurr -- silicate bearing racks, plattic when wet. hard when dry. Used n pottery, stonewere, file. b*ic*s. cements. fillets, and abra sives. Kaolin is one typ o* c:oy. Some day deposits may include appreciable quart?. Commercial grod'-s of davs *~cy contain uo to 70 o**r cent quartz. Most abundont greup of tr.e?e*ols. COfrposeC of silicate-. of olum-ngm with sodium, potossiurr. calcium, and rorelv feo**um Most economically important minerol. Used for cnramic* gles, abraswhw-'s, cements, insulation, and fertilizer. 5 mppcf1 50 mppcf' 50 mppcf' I I's'v.* llttodioM Itutil s.li;e% a iv .uk*]v.c.! ttv \ f!:,-; t r r c* ?*.*?- * *' f u v" rJtju'Mt.il frfi;*!i i.ii I !'* eu'iti*** uj l hioslu'M lm:J \-..!uc' >!':.n.xi1. fnm i : .ill :** rr* '( :\-t.illrtv I nv Mika'* v* **: p I hu'xIiaM lumis cn '.>! *wl***..?; * ir* "N,!:,.::-.-* ' :p tpouikK * m'c :*1.!! ;v? . -. i" \ .;.-v , .* *, '!:r.S * i *m !.:{rtf / rh.it? I *v: I1?;: ,, r'-J.i : ...... .............. ' * * v ! . < Ta21c.II. SEiECTEO INDUSTRIAL MINERAL DUSTS Continued . - ^ ;r. ;<i_ . SaiCAJK .. , ' ,.S ' Compounds niode tip oi (i.con, oxyCVr., and one o rrerv meteli wiihvor without hydrogen. -These, duitx coum nontoocific duo reactions, but generally de not interfere wiih pulmonery function or result in disability. Fullei's eorth................... A hydrated tilicoj*ojumjno fcir.pound, associated with jerr.e pjd*.vU>ed p, . _ . 50 mppcft :iller medium . end as o' ' catalyst and cotolyst carrier and in cosmetics ond nsecticides. 1- , Kaolin -. 4 type of clay composed at, mixed silicates ond used for refractories, ceramic >. ile. ond stoneware. . ............. : SO mppcf; Mica A large group of silicotes of varying composition, but similor in physical properties. All have excellent cleavage and con be split into very thin sheets. Used in electricol insulation. 20' mppcf t - Portland cement Fine powder containing compounds of lime, alumina. si|ico, :ond iron oxide. Used os construction material. , . t SO mppcf; Siliconcarbide 'Carborundum* Bluish-block, very hard crystals. Used as obrosive ond refractory material. SO mppcf' Tolc A hydrous magnesium silicate used in ceramics, cosmetics, paint, end phar- 20 mppcf' meceuticols, and as a filler in soap, putty,,ond plaster. . ", Vermieulite An expanded mica `hydroted magnesium-aluminum-iron silfco'e* Used in light- weight aggregates, insulation, fertilizer, and soil conditioners, as a filler- Vn rubber ond points, ond os o cotolyst carrier. . ., SO mppeft . Threshold limits given for xiihstancc* in -Silicate*" croup arc tor cornpounds coniaiiiini: /nt hail I pet sent crxial-inc silica. I m compounds containing more than I per cent silica, calculate threshold limit from formula: ' IJo . ~ SitI- ~ 5 ing anthrax; spores or wood hark, or grain dust containing parasitic fungi. . f. Irritation of the nos-; and throat, which is caused hy acid, alkali, or other irritating dusts or ntisis. Some dusts such as soluble chrontalc dusts ntay cause ulceration of ihe nasal passages or,even lung cancer. g. Damage to inlernal tissues, which may result from inhaled radioac tive materials such as radium and its daughter products and from other radioisotopes that emit highly irni/.ing radiation. Pneumoconioses 3-i. I'lwuniticoniosis conics from three Creek words that mean "lung." "dus:." and "abnormal condition." The present generally accepted meaning of the word is merely "dusty lung." The kind of dust inhaled determines the type of condition or injury. A number of t rganic dusts arc capable of producting lung dis eases. hut not all these disease* are classified as pneumoconioses be cause they are not all a "du*ty con dition" of the lung. 35. In very rare eases, enough dust had been inhaled to cause mechanical blockage of . the air space*. Hour dust ha* been known to cause this condition. Some dusts may be essentially inert and remain in the lungs indefinitely with no rccogui/nhic irritation, and a few- like limestone dust may be 'gradually dissolved and eliminated witho.it harm. * Silicosis \Y ,Vv The most important lung dis ease caused by the inhalation of mineral dust is w7/V'o--well-known in industries where crystalline free silica dust is present, such as'foun dries: glass manufacturing, granite cutting, mining, and tunneling in quart? rock. It is found.throughout the .xorid. and in the past it has liad mam names, such miner's a*thnta. grjnder's consumption, miner's phthisis, potter's rot. and stone mason's disease. 'Die same, occupa tional disease, however, is meant hy all these names, and it is caused by dust from crystalline free silica, us- uully quart/ Kv Table III. 57. Although considerable prog ress has been made in dust.control in industry., men: still dexclop sili cosis in plants and on jobs where d'.i't control is not adequate. 1-ngineering 'control is Mill, tile basic means ol presenting this disease, ami dii't control equipment and'proce dure* must be earefullv maintained . Silic.osis lias_ been detined as "a disease due To breath ing air containing silica tSiO^! characterized anaunnit ally by gener alized lihrotic changes and the de velopment'iif miliary modulation in both lungs, and clinically,-by *ho:t- ncss of breath. decreased chest ex pansion. lessened capacity for work, absence of fever, increased suscep tibility to tuberculosis (some or all of which symptoms max he present l. and by characteristic X-ray find ings."* 3`J. Idctnrs til inflnciuc. Sili cosis has .been knoxvn to maiiilc*t itself after widely dilfering periods of exposure to silica dust. Appar ently. development of the di*ea*e depends upon: a. The amountandkind 01 dust . in haled. ; h. The percentagehi tree Silica eon- l.iined in lln. dus1.. . e. The torm ol Ihe silica, d. The si/e o! the particles inhaled. ,`c. The duration ol the exp**siire. --Ctitiiinnctl mi /w `45 "Kcpoil < Joint i ul tin- I (itimim's- i n l>ncmiM<vi'fiii|*i* and tliv t Otuitiitice 'n Slandaid 1'i.uii.e* hi * niiipcn*.ilinn ul T IvViipaliunal IIi-imw.-* " 1 < n> /<"'. I,,; ;. Xiikiu.iii I'nhliv llcallli \*wvialinn. IT`ii> lltii.idu.ix. Sew S'tifk i1' p 11  I-. . I lie powers-ot resistance I the - re'pb;.tor\ diseases.. Cluist -X-rays < a result, the available lunetional ' individual concerned". ; may 'lio.v-an enUitteil heart iivfl re- ; volume of-lhe-htng-is reduced.- - jj. I he presence or alvscnec o| a com plicating pioccss such as infection. 40. M;hiv I henries haw; been advunccd over the yea's , to explain why cryxtiifli'ne free silica"acts';V it "" sul: ol the body's attempts to over come the resistance of restricted Hood vessels in the lungs. Pulmonary tuberculosis is a frequent eomplieatii>n'ahd (K:casi<malIy results m'dearfr. ' 51. In some advanced eases, the tibrous tissue will slow down or even prevent the diffusion of oxvgen from the lung to the blood in the 'capillaries, "'arid The HoOib In -the* does in the lungs. Theories have been based on the hardness ol' the material and the ' eireet of sharp edges. solubility phenomena, elec trochemical action of the crystals, and immunological reactions. 4A. Dcieciion am! r/nr/o/n.'icm. Silicosis may be detected by chest X-rays in each of the three stages However. X-rays alone are not sullieient for a positive diagnosis, for the shadows may be due to a area will not lv completely oxy genated. The tibrous tissue can also alfeet the blood vessel' by oblitera ting them or anting down the How ol blood. All- these cl'.eeis tend, to limit tile' rate at which oxygen is 41. It is believed now that the variety of other conditions, includ supplied to the body tissue'. i.m;'hy- fibrosis produced is caused not by the hardness or shatpness of the particles, but by .a combination of slight solubility with a physioehemieal effect and an immunological ellect--hut no one is certain of the exact mechanism of the disease. (Ex perimental work on the reasons for the development of s.licosis is still going on in various parts of the world. If the precise mechanism of silicosis could be dete'niined. better medical preventive measures might he developed and possibly a cure could l:e found. - 42.. 7i/im` ,vUigcx...Silicosis js ge t- erally classified in three - separate Mattes by medical authorities. More sophisticated classifications are some times used for the various X-ray states and complications of the dis ease. but for a basic understanding the three states give a stood break down. 43. The first state of the dis ease produces no disability. The allectcd man can carry on his work as well as ever. Frequently. the in dividual is not aware that am thine is wrong. and the disease is revealed only by opaque nodular shadows on a chest X-ray coupled with a known exposurs tii crystalline free silica. ing infection or another type of pneumoconiosis. The individual must have had a definite exposure to free silica, because only i: can cause silicosjs. The complete, occupational and medical history of the employee must therefore be evaluated before a conclusion can be reached. The eorrelation.of chest X-ray findings anil physical disability may be pivir in many ease'. 4 7. F-'rom most industrial expe rience. silicosis seldom develops in le" than live years and in many eases may take 2<> years or longer to become disabling;- - .=- 4 S'. The development of silicosis in its earliest stage is not perceived' by the individual. The disease cannot be cured by any means yet known. Tuberculosis is more prevalent in persons with sjljcosis. but the inci dence is decreasing, as it is in the general population. 4`J. Men with early signs of sili cosis are able to perform their duties and are not a menace to other em ployees. for it is not a contagious disease. A perceptible X-ray change is not giiuniils for assuming disability hccau*e most people show chest changes with advance in age even without exposure to dust. Where sfinn is the most obvious symptom. 52. As the inhalation of silica ' continue' over the years, the amount of fibrous tissue will, of course, in crease. vviih the ultimate result that the lungs will not readily oxygen tie sullieient blood for the body"' need'. Then when the oxygen demand of the body is increased by xonioM. the individual will feel distress with shortness of breath. 53. Aniiiri>hnti\ Iree \iiiiti dill.-rs from crystalline free silica in physical structure and in physiological elfeets. In the amorphous state, molecule'of silica exist in random orientation, which may be caused by 'natural forc es to form opal and dialomaeeoiis earth (kicsolguhr). Amorphous silica may be converted by artificial proc esses into such forms as silica gel. silica fume, and fused silica or quart/. 54. If amorphous silica is heated to a high temperature, as in calcining, forms of crystalline free silica called eristobalite and tridymile result. These intermediate forms ol amor phous silica are known as crypto crystalline (ultra-mierocrystalline. I Inhalation ol these crystalline forms can readily cause diatomite pneu moconiosis. 55. When dialomaccoU' earth i' 44. In the second state, respira there is a known exposure to silica calcined, particularly in the pres tion may lv alTcctcd in some persons dust, however, men with early signs ence of a trace of alkaline Hux. but not in all by any means. Labored of silicois should lv seen periodi appreciable quantities .ire convened breathing on heavy exertion usually cally by a phy sician. to eristobalite. As a result of studies is noted first, anil a dry cough also 50. Aitint! i>i yiiiiti mi the limes. made by the L. S. Public Health may be present. At the point' in the lung where Service, it has been recommciu cd 45. The third stage can develop silica ilti't is deposited and accumu that the threshold limit value :or after the second stage even though the lates!. a tibrous tissue develops and crude or amorphous diatomite be individual has been removed Irom ex grows around the particle'. Ibis placed at 2<l mppet t see '1 able III. posure to silica dust. However, tile fibrous tissue j tough like sear but that the atmospheric concent *a- pi ogress of the disease will lv slow tissue. I; is not as elastic as normal tion lor dii't containing eristobalite er without continued dui exposure. lime tissue, does not permit the ready be kept under 5 mppef. Mrealhing may become severely passage o! oxveett aiul carbon diox 5t>. Various commercial product' labored. The worker is lar below ner- ide. and it prolilerates. cut' down containing particle' ol 'il>ca under ' ... . ... ... !X. physiological cl I ecu of these piod- very -high c.mecanaaon* of'ceiiam. asbesips textile industry. it was \uct>'. have.-Out. been wvcll . defined.-'' _-.silicate dusts..-.. ' -}- -.'.i- jecommcniled that the -iln*t conccn- I'mil more *-\jvrieiice with human (O. Disabling ' pncumoconiosC* ' traiion be kepi at le** than 5 mppcf beings is available. il is believed from exposure to abnormally high to prevent asbestosis. {{valuation of tlicse product*. should he handled concentration* of.mica. '.ircniolitc.. an exposure uvahestos dust, is based with cere. - ' . talc. and kaolin dusts have been do- on the total amount of dust because = 57. H--xtf/rtr^rihod milie Hteramre.-T-he-clmicnl - at -hwi--proved out iir-practice- that silica is uiicomhincd silicon dioxide sign* are not the same for these *ili- if the fine dust is kept below iIk- (SifSilicates contain silicon cate Jii'ts a* for free silica, but the , suggested threshold limit, the coneen- mil oxygen combined wall other elc- . symptoms can be marked.- : trtition of injurious libers will also merits in a more complex molecule, v. b.V.Xhc Kody doe* not have ade- be kept within sale limits. Analyses, of minerals, particularly in ecological reports, are sometimes re- quale defense against indiscrimi nate amount* of dti*: of any -kind: Talcosis , . potted as percentages of oxide*. . Therefore, although specific symp b9. A* used in industry, "talc" which may include Silk.. Al~(l... ' tom* have not been described for is a very general term. To the geolo 1 -e-_.*. The Sifk. reported in many mineral dusts.Thc general ex gist. tale is a hydrous magnesium sili such chemical analyses is the tout perience would indicate that dust cate. which may be a relatively pure of rite silicon' dioxide present, both level* should be kept within-thresh ' mineral or may be mixed with tremo- the tree silica t if present l. and the old limit x-.ilue* or below (Table II1.. , litc or with dolomite depending upon silica combined in tlv mineral. Such where it is mined.:The term "tale" is malyses are not reliable indication* Asbestosis ... ' v applied commercially to carbonate of the silicosis potential of the f>4. .Asbestos i* a general term ap-. mixtures that have the same general material. ~ 5S. It isTmcomhined or free silica :li.it i* most important in industrial In*: exposure. So that tin exposure can lv properly evaluated, the per- cent age of tincomhincd silica must be determined by petrographic analysis using a polarizing microscope or. preferably: by -X-ray diffraction int.lxse* and special analytical chemical procedure*. ' 5'*. There ha* been some experimental evidence that some du*i* may lend to inhibit the action of silica on the body, but thi* inhibiting action i* so slight and uncertain that it must lv discounted in practice. In I act. there also is cxidcncc tliti: the nonsilicemis component* of a dust mixture containing, free silica max provoke a disabling condition more severe than that caused by the silica acting alone. Ml. With the exception of a*hc*to* and some tales, the silicate dusts do not ordinarily cause a serious disabling lung condition such as is produced by free silica.`Much higher levels of silicate du*:* than of free silica du*l can lv tolerated. plied to several mineral* having a fihfoti*' character These a*bcstos mineral* are hydrated silicate* of magnesium with" variable amounts.of. . iron, calcium, sodium, potassium, ahd aluminum present a* impurities. f'5. A'be'lds when inhaled pro duces tibron* .ti"iie in the lung* of both men and aiirmah; It ha* been shown tital' liber* .-.f asbestos must feel and physical properties: it also is applied to pyTophyllilc: a hydrous aluminum silicate, which frequently is mixed with a high percentage of quart/. The free silica generally found with pyrophyllitc can cause silicosis. It is therefore essential to know which talc is being used in order to- evaluate a :specilic dust-ex- po*uro. ` ly present for the' priHluclion i>l ' 7th , is' usually ' associ i;i/>fsrni/i. Other siheate. miner il* of . 'the same chemical composition but . tiortlihrou* in lorm produce no re ated .with tremolite talc. This disease , produce* ..changes in the lungs and symptoms similar to those of as- action or a relatively mild reaction, he*iosi*. but not the severe reaction of fibrous asbestos dut. Anthracosilicosis t I hc*c fact* le.ul to .the con . 71. .Imhnifovlicnsis. a complex clusion that .i*bc.*;o*i i* mainly the - form of pneumoconiosis, is'a chronic result of physical' irritation of the lung tisssiv and not oi a cliemic.il action, which i' liiough: to be one ol tile cause* ol *ilicosis. It i*. *u*jvcteil that lung cancer may be induced by .disease catiss'd by brealliing air con taining iliisl'lhat ha* free silica as one of it* component' anil that is generated in'the. various .processes involved in mining and preparing asbestos'.'However,, there i* no im- - anthracite (hard coal)*1' and. to a pressive ana'iiu: .<f evidence to *up- . lesser degree, bituminous coal. port thi* assumption. , . ... ' 72. The disease i' characterized t'7. 'I he line air-borne liber* of ' anatomically by generalized tihroiic asbestos can pa** through the upper - change*-'throughout both lungs and respiratory, tract to the lower pari* by the presence of excessive amount* of the lungs to cause irritation and i'l. In nutty industries, men>havc v.oikeil with silicate dusts that con tained no free silica without ilex elI'pment of disability or of noilul.ition in the lungs. The X-ray max show s'l.iiIon * indicating ilusj deposits in l ie lungs, but the pneumoconiosis i* lo^Num "asbestos bodies" where the lilvr* are encapsulated, t his dilla*e !ibro*i* probably begin* a* a "collar"' about the. terniin.il bionehiole*. I here i' ev idenee ihat other ininr eial* having a tibrdu* character can' nrodnee a reaction similar to that Diii-scu'w. ( .. I>: till \ ..lie J. M.. I itu.ihN. I. I...Miller. I. V\.. anil Viicrv K. K.. .1 Stttt/> **(. .!,%/*./%/* it: .1%. brs:t>\ , / %ni* . t . S. I'liMie Ilc.thh Hiilletin \iv ':JI. I S I'.iHie -lle.ilth - V*i\iec. VV.i%lnntff<*n T4. I) I I'iss. ` i c**i filially harmless. Howe'er, par- t:ally dis.il'littg pneunnvonioses liaxe been icported where men have ao: set !.m lone tvrio.l* '.'.nv i'.' a*hc*!o*. Tiber'.gla**. however. Itvs not proiluee stieli a ic.ietibn. os. I .'Mo.v'me *a 'tiidv by the l' S r-e-e. I S . ",v i'a ol-b-p;' //. rj t W.i.v -v !l ..N,|,nMu IK'.iiifi` Hnllx*!in ::i. I S lle..irh V:v:U- .W.-.+h ' - * 4 t > t *v i ,'  tcriiiJ. -Such *1 unes. on /.-autopsyyucc: coal bl:iek. '' 73. Symptoms found in earlv stages of the disease arc shortness of breath. couch with a coal-black ., 'fJI.Jup.V porin .iji ,th*:..c'ncsi. awl-in. sonic cases physical weakness. In the advanced stage*. there are loss of weight anJ decreased capacity for work, partly caused by pulmonary infection (frequently bronchitis), and in some case's there ntay be heart, failure'. 74. Experiments with animals showed that mixtures of coal and quart/ produced more fibrosis than did quartz alone. The harmful elTects of cot11 dust do not come only from the silica in the dust, ('oaf dust alone in very heavy concentrations over a period ol many years can cause' breathlessness and ventila tory impairment. .... ............. Miscellaneous pneumoconioses 75. Even though ;i dust is -.T.is*ilicd as harmless, excessive amounts of it can lead to trouble by causing a pneumoconiosis or simply by me chanically. irritaiing .ike .walk of the respiratory system. Moreover, even though there is no chemical or physi cal irritation: mechanical plugging of the lungs and interference with their ordinary processes can result. Mica dust and kaolin dust are two good examples of dusts that ordinarily are considered benign but in excessive amounts can cause a troublesome pneumoconiosis. 7b. Mica pneumoconiosis has bee-1 observed in grinding operation* where mica dust, but no free silica was present. There were marked chances in the X-ray pictures of the hint's and some disability. The ca*c* occurred where the dust exposures were massive over many years. 77. Ktuilinosi* has been described as a condition induced by inhalation of dust released in the grinding and handling of kaolin (china clay t. Whore the eases occurred, dust levels of several hundred million particles per cubic foot of air were common. 7,S. Aluminum du*; k not consid ered to be harmful except where exposure* are massive. Without ad verse elTects. alumiitu tt du*t inhala tion has been used ,i' part ot an endeavor to prevent silicosis. Ako with,hi; adverse elleet*. evieii'ive exposure* to aluminum dii't have oc- vL.:.'.a g.'a.it.ag oi aiumuuim ..parts ansi, e.t'jiogs:. It. Cun. therc-fifc he con^luJeJ thu: re.i-oriabh eood control uiH prevent harm front alu minum. djst. ~'K Bauxite pneunnvoniosis (Slia, ver'- disease) has -K,err-fotmd onlv in worker* exposed to fumes contain ing aluminum oxide and minute or uhranvcroscopic silica parlie'es aris ing Irmn smelting bauxite in the manufacture of corundum, an; im pure form of. aluminum, oxide. It i* essentially a diffuse interstitial librosiv and marked associated em physema. with a complete absence of any nodular librosi*. I; definitely thvs no; occur from the ii'C of cor undum grinding wheels or from oilier forms of aluminum oxide. XU. Some pneumoconioses may show marked shadow* on an X-ray ;ilm: these shadows, without tile nec essary. information on the exposure of the individual, may be alarming in a general X-ray screening pro cram. On clinical examination of ind:\iduai' show ins: the X-ray mark ings. however, olleti no disability or symptom can he lound. .. -SI..These shadows are-lrequetuLy encountered when the dust* contain atoms of. relatively high molecular weight because tile heav ier atom-, are fairly opaque to X-rays; Insoluble barium dii'i and tin oxide dust*, lor example, can show very marked shavlows on X-ray lilm* without pro ducing sbens ol significant pathology i barium dust that is soluble in the I'oily lluiik can give a toxic reaction I. Iron oxide, particularly ex cessive fume Irom welding ojvrations. may produce vh/fiov/v with a pigmentation ol :hc lungs (black in welders and red in iron ore minerst without disability. The X-ray shad ow* produced by the iron oxide in me lungs are somewhat similar to the shadows from silicosis. Because of this similarity, dillerential diagnosis is often difficult, and heavy exposure* to iron oxide di -I .nui fume may lead to medieoleg.il problem*. It i* therelore important to control iron oxide exposures even though sjdcrosi* is not disabling. X5. Limestone, niarhle. lime, gyp'iini. and portlaiul cement dusts app.uenili have no serious elleet even .iftes lot.e . xposines. Also, ntanv sili ca;.' .. id o'.ite; mineral' have not caused tmpairmen: in individuals in haling 'iv >lii-t'. and tile resulting pneumoconioses are generally classed 'asi benign.- - ......... - Toxic Dusts and Fumes . X4. Systemic reactions are caused by toxic dii't' and fumes of various - elements->tnd their eonijvmnik and' by certain organic compounds. All metallic lames are irritatin'*., especi ally when fleshly generated. Indus trially important metak and tiwir compounds that can have a tc-xi ; elfeet when the dust or fume is in haled include arsenic, antimony, cad mium. chromium, lead, manganese, mercury, selenium, tellurium, thall ium. uranium, and a few others.* X.V The elleet of some metak such as magnesium and /inc. appears to be transient. Only limited cam are available on the exotic and tare earth metak. Xb. Although the dusts and | nines -from metais with low toxreriv do not need a* much attention a* the dusk and fumes from highly toxic metak. they should not be neglected or disregarded, 'flic metak with low toxicity are controlled more readily hecau.sc greater amounts can !v tol erated., hut .their.- dusts and. fume* should be kept at reasonable level* . since excessive amounts of any of them can be harmful Cl'able III). Lead poisoning N7. Although extremely severe ea*es of lead poisoning are rare in industry today, lead exposure* must Iv controlled to prevent even the moderate symptoms, which can be troublesome. Inhalation of tile dust of lead compound* i* the most com mon mode-of entry of lead into the system. Ingestion of lead compounds can add to the problem if personal hygiene i*. poor. Worker* should therefore be encouraged to wash thoroughly before eating, and lunch room* should be segregated fioni work areas. NX. It should be reeogni/ed dial lead is a normal constituent of plant* and animals People ingest and ex crete lead daily even though they are not exposed to lead in their daily work. The body can handle See the following NalM*n;iI S;ifet\ Cmincil i Shed*: Anumnn\ mut h\ (HS; . J r\t ru on*i //> f'tnr- ,uintt 4 ( m/tnntfti. *1. Wic.d.'c 'ifi'B. Mutivnt t'M si if.. r1*'. ftfiimiim. -S<. /ftit mu! /nu l1*": /tn mum /'</<< and eliminate 'in.il! .im.uini' without ]_ harm; \viyu. r;Mc\ pieced, die: 1 normal excretion level. build-up oe- ciiT' in the lvn.lv. there i' a 'ale level nf ab'orplion. and if ille Coii- eelilr.ilinii of ie;u du'p in the air ,. of ...vv-o/k...jre; iv... is . ke pi.- below. ll us- thrs'hold limit, there 'hould Iv no dilticuliy. S`). I he imiviri:mee of maintain- ine the concentration of air-borne lead at :i very low value stem-- from lead-' hiel toxicity and- it' tendency, in 'iti:tll amount'. to accumulate in the linni:m system. When lead ab- s.irption in the body retiehes ;i 'iif- lieieni decree. symptoms of poi'on- hie or intoxication appear. Beryllium intoxication - tl. Beryllium in:o\ie;itiou is ,i severe systemic disetise that c:in re sult Iront the inhalation of massive - doses of. dii't of metallic beryllium.. Ivryllium o\idc. and some soluble beryllium compounds. I here are two forms of the disease. One is an acute form of chemical pneumonitis with couch, pain, dilliculty in breadline, cyanosis, and loss of weight. In the chronic .type, known as berylliosis, ilicre'ntay he loss of appetite and weiulit.. weakness, couch, extreme dillicuily in breathinc. cyanosis, ami cardiac failure. Mortality is hich in chronic beryllium intoxication, and many who survive sulTer from pul monary distress. 'll. Individual susceptibility ap parently is an important factor in the development of the disease. In many instances, one employee lias devel oped tile severe symptoms while oth er employees dome tile same work have shown no 'it'll' of disability . 1I2. Beryllium intoxication has never been demonstrated in individ uals inininc or llamllinc ore only, riicrc is no evidence ol imox cation from the imccstion of beryllium oxide, beryllium metal, or any of the beryl lium alloys. Only the inhalation of beryllium dust produces systemic disease. Because of the severe nature of the disease' and because there i' no way of prediciinc who will de velop it. extreme care must be taken to control the dust ami luine that arise in the handline of beryllium, its alloys, .md ,|s compounds. Beryl lium is toxic in such small i|iiau:;;\ as to be considered the most toxic o! all clement' vet i::ve-ticat. .1 ABIE III. SELECTED TOXIC DUSTS AND FUMES Substance Description and Effects Threshold limit in Milligrams per Cubic Meter of Air' Antimony Arsenic Barium 'soluble compounds' Beryllium Chromic acid and Chromotes Cyonide 'os CN` Dinitrobenzene Fluorides Hydroquinone Iron oxide fume lead Ivod orsi-note Magnesium oxide fume Groy metol often associated with ieod "ond orsenie. Ha-'or^ous from inhala tion and ingestion. Soluble salts may couse dermotitis. 0.5 Silvery brittle crystalline metal. Hozordous from inholotion and ingestion. Usually encountered as ofiehic tri oxide. ' ' 0.5 Soluble barium chloride end sulfide ore toxic when token by mouth. 0.S light weight, groy metal. The metol. iow'-fired oxides, soluble salts, ond some olloys ore toxic by inholotion. 0.002 Red. brown, or black crystals. Caustic action on mucous membranes or skin. 0.1 Nonvolatile cyonides ore ingestion hozords. Cyonides iqhibil. tissue oxidation . upon inhalation and cause death. 5.0 'skin' *' . Yellowish crystal. Hazordzus from skin absorption, inhalation, ond ingestion. 1.0 'skin"t Inorganic fluorides are highly irritant ond toxic. 2.5 Colorless hexagong! crysto.ls. Contact _ with the skin may couse sensitization and irritation. Excessive exposure to dust may cause corneal injury. . J.O , . ., Major sources are cutting ond welding. 15.0 lead fumes and Ieod compounds couse poisoning alter prolonged exposure. Most important means of entry into body is inhalation. Skin obsorption is of sianiliconcc only from such organic compounds os ieod tetroethyl. 0.2 White crystals--highly toxic 0.15 While powder. Inhalation of freshly generated fume moy cousc metol fume fever. 15.0 I lie's- t!tis''l:n!il littiit s.iluo vss'tc ailopls'tl hv tits' Ams'ris'an Confs-rsTtsV of Cioscrn- nis'Ml.il Itulii'tttal llviuvni't' m IWs'. `>-1. \\ hen tils' 'oiuble '.ills of Ivryllium. especially Ivryllium lluorivls-. conic in coninct with cuts or abr.i'ioii' on the 'kin. sleep ulcer' may Iv formed thatmcal very 'lowly. Complete *ureie:;l exei'ion of tile ul_eer i' 'titivtime' rcijiiireJ in order to elleel liealine. Metal fume fever **.' Metal iutfie fe'e: o an aeuie by a briel Inch expo'itre to the fre'lily eetierated fume' ol metal' 'i ell as /ine or mattnc'iuni or their oxide'. Symptom' appear from four tii twelve hour' after cxpo'ure ttnd eon'i't of lexer and 'hakine chill'. There i' eomplele recovery U'ltally within ine slay, and ordinarily the employee can return to the *ame job without recurrence. However, alter a period in which there h.t' been no . table iii: selected toxic dusts and fumes;. Cocumu.d: . Substance .. -. Oescriptioncnc Elfecn . Threshold limi* in Miltigrorm per Cubic Meter of ^ir" Manganese Silvery groy metoi. Hozcrdoji from inholotion of fumes or dust. 5.0 Penfochlorophenol Phosphorus (yellow) Picric ocid Selenium compounds Sodium hydroxide Tellurium . Dcrlt*colored flexes. Harmful dust. * 0.5 Akin") Err its toxic fumes when heated. Poisonous mainly by inhalation. Severe burn hazard from skin confect. 0.1 Yellow crystals or liquid. Exp oiive-- particularly metallic softs. Err in toxic fumes on decomposition. 0.1 skin"1 Toxicity varies somewhat otcerjing to the solubility of . the ! pacific com* pound. Often couses contact dermatitis. White, deliquescent pieces or lumps. Has severe action upon c.l body tissue. 0.1 2.0 Similar to selenium chemicolly -ond .m - 0.1 physiologicoi effects. ' Titanium dioxide white 10 block powder. Cons dirred in the nuisance category. 15.0 Trinitrotoluene Colorless to yellow monoclinic crystals. Emits toxic fumes of oxides of r trogen when heoted to decomposition. Highly poisonous explosive. 1.5 'skin**1 Uranium Vanodium pentoxide Zinc oxide fume Highly toxic ond o radiation hozord thot requires special considcrorion. 0.05 `soluble com pounds' 0.25 `insoluble com pounds! Yellow to red crystals. Acts chiefly os on irritant to the conjunctive end re spiratory trod. 0.5 'dust' 0.1 fume! Amorphous white or yellow powder The powder is essentially unt<*C. but freshly generated fume may couse metoi fume fever. 50 Zirconium compounds Most compounds ore imolubi* ond hove low toxicity. 5.0 These thresholvl lin-.ii v;ilue were iulnpictl hv nc American ( ontetenee of (invernme"tul liirluslri.il 11\eie.iiM- in l`*t>2. *" I be tvorvl "skin" in this table inUicale* th.il the *i.hl.incc can penetrate the 'Lin In contribute lo the exposure. after :i layolf. rcsumpiien of exposure is likely lo brim: on an attack. l)ft. To cause metal fume lexer, heavy concentration* of fume* are required. Zinc ovule fume i* ihe nio*t common source, hut case* caused by the inhalation of fume* from maunesium ovule, coppet oxide, and other metallic oxides have al*o been reported. 1 he condition doc* not occur from the haiidlinc o! these it re'uli' only from the inhalation of evtrenuly line particles freshly formed a* fume ( nascent fume). '!?. Nickel, mercury, and other metals may al'o'produce a fever fol lowed n jhe tovie elTecis of the element. Allergic Reactions US. \\ hen in the torm of dust, a laree number o! materials may eau*e tible individuals."T.xamplex-of sue!: acenis are certain animal predict*, food*, drusts. and chemicals. Ih. hodilv systems .usually involved rr. allergic reactions, which may he quits severe.' .'I'rV'tlVc *Vihr rc'piratorx s\s. tent, and ca*trointc'i:nal swtent. ()eca'ionallv. two or more 'Viiois ais involved. Some ol the allergic reac tions are dermatitis, hav fever, asth ma, and hives. ')'). Usually, the victim is' subject ed to a series of exposures without any reactions during which sensiti zation is built up. These exposures may occur coitiinuouslv lor years ritert. ;it tile end ol the "incubation period." which varies according to the individual, a reaction is pro duced. 100. For a true ailcreic reac tion two factors are required: a. ' history of poor exposure to the material involved isometnnvs not kilovi 11 In atl'eclcil emploxeest. b. A "chnllcnite dose'' v'l the mate rial. which provokes the allergic reaelion. 101. Continuous exposures max act .as. "dcsett-sitizini:. doses."'- .mil under these conditions an allergic individual may work without incident for lixnt* perilhK of time only to ind that re-e.xpostire after removal ft tun the sensiti/ins; material ( such ;is after a vacation i causes an allergic re sponse to recur. 102. Medical and enuineerine rec ommendations to prevent a!le*v:ie reactions arc based on prevention ol exposure by means of personal pro tective equipment, ventilation meth ods. or removal of sensitized individ uals ftom tlie exposure. . Infections Infliction ond pneumoconiosis I0T. The presence of pu moiiarv disease that `.ienilicantly interh res with the natural dcleiises aeanist foreign particles may increase *useeptibility to pneunioconitrsis. Con versely. a pneumoeoniotie lune is more prone lo infection. For exam ple. tuberculosis occurs more trequcntly iimunc silicotic' than amone normal person*. Severe disability or dettlh of a silicotic, when caused by pulmonary conditions. usually res ills from complietitinc tuberculosis either alone or combined with other iiilccliors. Bacteria and fungi lections IrnnvjIy. iiilKiIjiHoa.i't'.l'iaC.'-: l.'-ii.i airfu'upi exist' in' several inliintrics. Pulmonary anthrax limn toe inhalation nl' dml coniniiiinp an thrax spores fun dm ur'rcd amoiip cm-' j'Kn vxn. VI'.--,U>.ih*:J)iudluu;-<l'.wool and the crinhlnp l bones from infected animals. I 5. I iirijri (molds) prowinp on .Mill ll.lv lVCII lOUIld ill tiv spiltlim ol workmen shovclinp tlw prain and arc believed l.t Iv tile came of out breaks of respiratory disorders. Iimpi It mini in sitpnr c:nv residues i bap.nsc) lire believed In Iv part tl tile cans: of /'ueinvows.- l-'urtaal spores lo'rmcd .under the bark ofmhiic irets have (ven Named I'nr respiratory ililli.eultio nmonp em ployees "lin debark dry lops. 111!'. Although llie incidence of occupationally related bacterial and lunpal infections isround . In be. rilaliveiy low. tile respiratory ellecN tan Iv troublesome and. in llie case .>! pulmonary anthrax, even fatal. I lie bade methods of enntrnl are the same as those I'nr the pnetimoconio'is producing dusts, but sterilization and disinfect it'll, niiist Iv added. . Radioactive Dusts* III". A radioactive contaminant may .ilfer a chemical tosieilv hazard in addition in an ionizinp radiation exposure, anti it may !v present as a sas. dust. fume. t>r mist. lus. Radioactive contaminants taken into the body max be dejiosiied in various nrjails where they consti tute sources of internal radiation. Hie chemical characteristics of the radioactive contaminant or isotope determine the orpan in which it will Iv deposited, llie excretion rale is also dc|Vinlci:t upon the chemical nature of the isotope. Ivcause the radioactive isotopes of an element follow the same metabolic proccs. as do the 'table isotopes of that ele ment. I"`h If a radioisotope has been deposited in the body. the internal exposure is repatded as s'ominuniis until the isotope is lost In radiolojicai or biological decay. lit some eases, exposures max las; a lifetime. I .1 <!v t.iiivi ! ss nsx, *n ij :. ii c S I tv ! V ..:*! . It Vs: s J, :; .1 J*:i . 's s i! tv ,, 11 .i i*1*. t : s i'* i*' i I ' I * : i ,* * j * o K i ,-Mfk Since: radii*-sot<*pes' are TftV T.11eeiirre 111 TyreCo m nieiHIe'd Ice lively taken up in individual or threshold limits ol particular dints gans. they max cause only localized c m be found in the most reeentlv irradiation. J jv radiosetisitivity of published ACGIH li>t. or the the orpan dictates the evten; of the ACGIH can Iv consulted direetlv. lraAm.1 -of--a-'p.TTlr.'nl:ir"r;riltiiairtf<V" 'fiifomiafioir oh ilireshold limits ako substance. Solubility anvl particle can Iv obtained from the National size determine how muelt of the ac Safety Council, state tvcupuiionnl tive material will pain access to and health aecncics. tiv American ludm- remain in the blood stream and var ious orpans. . . . trial llystiene Association, and com pensation insurance carriers. IH. If radioactive air-Nirne con ' .117. Nil one knows the exact tamination is known tii Iv present, concentration at which men will start control measures are mandatory. .If to develop 'ilicmis. asbestosjs. or the presence of contamination is un ieail poisoning. *>\`iih some toxic known but suspected, sampling ntmi dmts. however.'experience has been be done 'to deleniiitv whether or not wide ctiouph to establish tiv present air-borne coitccmrariom of the ra- .threshold limits as fairly reliable. dioisjcope are below ihe threshold ' TIN; I "or example, if the level of limit value. ' lead in a workroom is kept below 112. Good personal In dene and it 2 mp cu m. experience has shown pood oper.itins: tee!mii|ues are much that cases ol lead jnioxication will more important in the ' handlinp of "ho; occur. 1-Apcricticc ako has radioactive materials tittin ;n the h.m- shown that many men can tolerate dlinp ot most other materials used in lead levels well above *.2- mp industry. eu ill without sipm of trouble. II.'. l-mpitvefinp controls lor rtidioaetive dmts are similar to those for other dusts and depend piimarily upon capture at the joint ol genera tion. Ihe difference lies in the fact tiiat emmols for -radioactive dusts must Iv extremely etiieieut. I hrcshohl limit values lor ladioactivc par ticulate mailer ate vety low. ami in some Case' l<i" per cent ellieiency in capture and retention is leipiircd. Mineral dusts 1 l`h In the I'nited States, the . iltieshold limits Tor'-mineral dints are expressed in millions of par ticles per cubic foot of air (itippcl l. I lie concentration of a mineral dint is determined by eountinp dmi par ticle' that tire less than in microns in size in an nlii|iioi sample after s.implinp a known volume of air in a known volume of liquid. In Permissible Dustiness 1 l-t. liiie'iioK! limit values ol some l-tiropean countries, mineral dints are weiphed. and permissible levels tire expressed as milliprann miner.ii dints and toxic dints that ol dint per cubic meter of air t mp is. tinte-weiclited avetace eoneentratioiis sninidcied i\rmisi!'le tor ex posure' o! eicht 'louts pet day. live ci. ml. In linplaiul and some other tit.ms. the number of particles per cubic centimeter is the current basis days pj: week have been pub ot measurement. lished by tite American (`onlerenee 12<l. In comparing l.'nitcd Slates ol Governmental lruhntii.il llypien- and loreipn dint counts, ji is helpful i'ts. I !ie*e value- iiave been obtained to keep in mind that MKi particles irom the evperieive ot main groups in iiuhn'.tv and lf:n t.iboralovy pvr cubic centimeter n equivalent to appioximately .' million particle' siudies oil animals I hex are re ;\r cubic foot. viewed .mmialiv aril! chanced ;n nee- 121. It i' vlillicult to eompaie in tits- !' si-si's i S c\j VI k'fK'C dint counts with result' obttiined on ii5. i; v.:11:. - ,i:e set I'lllv the basis ol weipht. However, with .1' ll 1the bc'l practice and cuhci typeo! uieasurcmeni. :i thresh t:,- ii.'l ; `` :v .`'iivit. m! absolute old limit can be set as an objec 1 v' n le.noM.ii'i-e .I'slir- tive. I.vpericnee lun shown that .:lW il'ai h *!'.i! ih-e.ns" ill m liiit.umnp dint level' below the ; .p- at. kept tv- ic.nmmcrulcd tluc'hold limits has ' . e n S' : s." ' s' . - ' ! ::.e - -:`v: liaiul. ,, .1 '! 1 -e :-e hseh : .!e- '" ' ' !s` ; e ev :: - ic-uhed in a eie.it deereme in the ineuletice nl i >.cupatii -ti.i! lnease l;iirl constituent of the dust. It >ih- iMvhc prcxxfnred'. IhcscilmiiV must not ho exceeded. Concentra tions of dusts containing loss than 5 per. tent free silioti should noi- exceed 50 million particles por cubic J- .*-fTOt"-f mppcf r. " O'rVcmrilTions ' i if v dusts Containing from 5 por coat to 50 por corn froo silica should not exceed 20 mppef. Ousts containing more than 50 por cent froo silica should ho kept at concentrations below 5 mppef. ' 125. As more experience accu mulates. original threshold limits sometimes can bo modified. In some eases, it has been necessary to lower the limits, for the objective is to- protect the more susceptible indi viduals. In a few cases, experience hits shown that the limits were too stringent. and it has been possible to raise the limits to allow for more reasonable controls. - ; Figury 3 Eoeh of tb-w grinding Is pail-ally endow'd by-on nhousi' Isdod. EH Idem iotol nxtsa-iif is acs---r-d by drowing the dot:, imo ihe hoods, through branch ducts, and into o centra! duet which leads to the collection point. -Courtesy American Foundrymen's Society Toxic dusts 124. In till countries, threshold limits for toxic dusts are expressed in milligrams per cubic meter of air. With toxic dusts, the average .levels.must be kept below the sug gested threshold limits. In fact, it is advisable to keep the levels of toxic dusts as low as practical in the specific circumstances. I.it'.ie in the way of experience or data will he developed if the levels are kept unusually low. but few if any eases of occupational disease will occur from these dusts. Nuisance dusts 125. |{vcn though a dust may Iv considered generally imuvuous and not he recognized as the direct cause of a serious pathological condition, its level should lv kept as low as is practical. Dust levels well Ivlow the suggested threshold limits are desirable. 12f. A concentration of 5<> mppef is suggested as the threshold limit for a number of nuisance dusts. With good engineering prac tice. there is no need for this level to be exceeded. Any reduction Iv low this level will inetease the com fort of employees and improve plant housekeeping. Methods of Control 12". Various methods of con trolling ilii'is. mi'ts. : .ik! I times are available. Basic engineering dictates where ..i , j. > iv made dustless through control at the source. This inclin'd is always the most effective, for it either com pletely prevent' the contaminant from entering tile workroom atmos phere or limit' to sale level' the amounts that do ecape. In addi tion. this inclin'd is generally the least expensive. ITS. When eonttol at the source is not possible, other methods mav hiive to be considered. Anv one i>r a coml'imitiou ol the lollouing tv pc* s f dust control mav be in-evlevl i" limit the cxpo'iiic. a. the dii'tv op-et.:ln'n mav lv en closed. vs till I'l VS lihl'lll II llVul C'-li.ni'l sssiein \n enelr"sd op- er.iti >n generating l.ugc smanlilies >>( sins! iisii.iIIv need' t" he ex- hatis'.esl. i'i the dii'i will ts-.i1. nits' the siniiMiuJmg atmosphere I v-inipies .-.re s.in.lht.is! cabinet s or saini-'I.ist rss'iiis aiii! ills- sirv bovs-s I'svl t>< handle i.uhs'.icme niaterials. b. the Justv work mav iv pcrtoimcil in a separ.ile hinlJmg or m.r. Iv iss'l.itsvl bv p.irtiin'iis io isillies- the mmilvr >'l empiovee evps'sesl ts* 111.* sliist. Ills' empii'vs'es is ho ale till heme evpossv! s|i,>ul,| he pfo- leetesl bv re*pir.iitirv piolsvli'c es|Ui|'metil . e A le" ha/.itsls'ii* m.deiial mav iv 'iibst lute's!. I .'I instance. *teel -hot mav be uses! uisteasl .>1 iliea * a I .si ill ab:.i*iv s* elea.'iine .! Ksvp ne :!ie iii.itsti.es moist aia-. lv a p.'.ietie.ii nv.a's ci'ii'ii'l I '..ill pis* ale tile ...letr! af.l louiulrv aiul the use ol vs.ilei in slrilling. e. I ocal exhaust sv stems max be in stalled with virutallv lull or partial enclosure, I:\amplc* are an es- ' haitst IioihI 'om a grimling wheel f f igure .<1 aiul an exhaust hood at a bagging s'r filling s'peration. I. (ieneral n>on! seiilil.ilis'ii can be used to dilute the sliist In ,hI< ing la.ge mtanlit'es ol air and tints preventing bttilsl-iip ol dust eoneentrations. I'sample* of this meth od are roof tan* ami ri<ol moni tor vvimlovvs. lint it gener.illv i* itulfieicnl and expensive to alloinpl to eonttol eoul.imin.iitls bv dilu tion. g. I he sittstv vvi'rls mav Iv pertormesl at night or on week-cmls li' red .tee the nitmlvr ol emploveos evpossvl. ( Is'.imug dust aeeuuiulatioiis trom iwerhsMsI Ivams. lor instaiisv. i* preier.iblv ils*ne slurmg a weekend. Ills emplovees svhs arc' evps'sesl shonlsl wear appropriate 1>|V 1 respirals'tv prolsvtive es|iiipmen:. It. I he number ol working hours at the particular exposure can lv reshisssl. However. other methods s>l cont'ol are preterable. f *e 'l is'spiialoiv proteetive espupmem approved li't the exposure bv the I V llircait ol Mines sail give eveeilenl proteetiim agari't all tvpes sit dust, but lit most ca-c* should lv ei'ii*tils;s`d li* ,i tem pi ir.i iv control measure. In > s.uiill l.i't risim. how eve:, .ui'iipplisil helmet' iis.iallv ale icsimicd s'oi!t*nnotisl\ lint me '.'s :-d .' 1* -.tv: I )ucts.. tvV carrv the' contaminated : L'is. Hndugh air- mi'.si.;besup- H v.yi/a*.i.r*l(o*..,.ti .c.,cn,,tr*a.gr,pVo-tIn'**r...,* . - *.. r*.. plied' to' die vWm TrOnf ilfe'oufside't'rf e. Dii'l and tunic collectors.'to clean replace '.he air dial i' removed by. the air before it i* discharged. the exhaust system. Otherwise, -d. A .Ian and motor io-keep the air there xx ill he interference with other moving through the svstciii. exhaust systems in the area or with ..... 'W.-AVIVW the***/'pans "'gas* or bil'llarties' ih'<iie1!ri:Sy Turuaces;'' should' he designed and installed to Great ditlieuhy has -occurred where perforin it' required function with an exhaust system caused a slightly , respect to the system as a whole. negative pressure in a room con ' design of the exhaust hood'demands taining a gas furnace. As a result ', tire greatest care. The degree of air came down the furnace Hue. control of dust at the point of gen and die area became contaminated figw*< 4. Sii'o* fhi* vwtn^-ffOM grinder n vied in n miir-tr positions. the letol eihoutt sys tem nrst hi* odjvllohle. The flerihie duct 'A) t**'tnii** mevement ol the rihowlt hood B1 Ol needed.'-Coy* ti-.y . Amefi<on f oundrymm'i So* eration dr dispersion is determined by the shape of the hood or degree of enclosure, die location of the IiihkI and its distance from the dust w ith Carlson monoxide from the fur nace. 13*). \\ ilh small exhaust systems. . . air that i remoxed usually can be; <**iy . ' ` source, and the'rats'" of flow of air replaced by infiltration llow. but into the IioihJ. A poorly 'designed larger exhausts may need a positive nevertheless. ' sllOlllif HOT he Cl'li- sislcred as ;i universal substitute li'r adei|tiaie local exhaust re , inis\;M. . elimination ,,o>l. the con taminant. or containment. I'w. Main states and municipal ities hiive dust control codes or or dinance' with which employers must comply. In a few slates, for instance, written approval of plans must tv obtained . before a local c\haiisi'system is installed'. Hitch' " employer should therefore know his state ami municipal dii't control re quirement'. K'o. Haeh type of exposure must l\- eonsideteil separately. l;or c.xample. a local exhaust system suit able for welding or canine ol steel ` might not !v satisfactory lor weld* ills* or cutting steel coated with red lead. ' hood'can' make an exhaust svsteni inclTcctivc. 1 34. There is no standard hood. In every case, the hood; must be designed to fir :tlic specific opera tion anil to make the exhaust ytfectixe without interfering with the operation (Figure 4i. Among the factors to be considered are the nat ural air currents in the room and other exhausts or windows in die area./--........ 135. The h>od should be shaped to conform to the shape of the area of dust production o as to secure reasonably uniform air velocity over this area. A hood which does not en close tile process should be placed with its opening as close as possible to tile point of generation of the dust or fume -t figure 5 l 'because the velocity of the air in ,thc /one of the hood inihicnec isinversely air supply t Figure 7|. A it adequate supply of make-up air. tempered , when necessary, is one of j the most frequently overlooked fundamentals ' of ventilation' 'Air always should he supplied in quantities equal to or slightly in excess of the amounts exhausted. - 140. The si/e of the duets, the type and si/e of the dust collectors, and the type and si/e of the fan atid ' niorbr' I'expldsion-prixif wheTC' necessary t are among the other fac tors which must he considered in the design of an exhaust system. Pre venting ignition of a combustible Local exhaust systems proportional to the square of the 131. A kval exhaust system for distance from the face of the hood. the control of an industrial diK or l.'h. I he h.s>d opening, or part fume traps the air contaminant of it. should be located so as to re near its source so that an operator ceive directly iltist that is thrown standing ;ii the process is not ex posed to harmful concentrations. I he sxstein should be designed to enclose the privess as complelclv :is possible, t ills method usually is oil along a well-designated path i l-'igure o i. 1 he directional energy if the material can thus l\* Used for its own capture. Air movement must always he pa-t the employee, preferred to general ventilation, theti oxer the dust source, and di but shouM be used onl) when the eontaiiiinaiit cannot be controlled b\ jsol ation. proee'W rc\ Mon. 'r stibsiiiulion of less harmful mate- rials. 1 veil though a privc'XX Ii.in been isolated, it max still l\\\1 iti rc .. local exhaust s\ * U-:n i X local evil. lllM s\ s*,C 111 1x* 'll* s; v ! s, , t.-iit pi ,:icij\: 1 p.i :is : II.... ,!s oi oilv: : nix!' W hie ft reetlx into the lace of the hood. 13". The Ian should he .of siilli- eieitt capacity to' maintain tile reuuired air capture velocity at the point of generation o! tne dust. In ternal baliles should be installed to guide the air flow where it i* ill*"! needed. Mattees aoaU he piovidesi whereve: p*>:!'le reduce ttie air :5ow .;.*e.i' where no Jnr > ;:*.freed :h..: oir-tlow eoai.'ti!* 5 To <** fn** p*9p** or lootf. ih* heo^% *# !#% h*t**l (OP h>< UO\l*iO*'rf 9% {low to lw*"OC* xpowtx ox i>n<ticoi Suth >\ 'orf* tididbl** t> hv i. O * vontamjnani is a prime sjfeiy con as readily as dry dusi--advantage ot . a thorough pre-employment historv sideration-." Since disimssiiifT 'of- the- 'iffis faer sb-juld he takvn -whenever.v ; w fttr The- ocenpatwrfSP KacKst'ouiul subject of exhaust system design is beyond the scope of this data sheet, possible. Carloads of drv minerals in some cases may be wetted down given in detail, (.`best X-rays should be made of all new employees who an experienced ventilation engineer-, before tliey are unloaded.. Aisles in will .he working, in dust-exposure* should he consulted. . foundries should he wetted down thni could produce disabling pneu- 141;- *A1SftiT Information ciiffbe ' ' to prevefrt disperstrf ot the dusf by - YvifNnrlibsis; 'riie Viami nine plivsi- secured from several excellent pub lications. one of which is the current traffic. Water sprays can be used at some operations. Wet drilling cian should decide on placement of those who have, pneumoconiosis, edition of Industrial Ventilation-- methods can be used- for rock drill active or significant past tubercu A Manual of Recommended Prac ing to wet the dust as it is formed. losis. abnormally low timed vital tice. published by the American Conference of Governmental Indus- ' Personal protective equipment trial Hygienists. Another is the 14ft. Respirators of various de chapter entitled "Local Exhaust signs arc available which will give Systems and Ventilation" in the protection against toxic and pneu Accident Prevention Manual for moconiosis-producing dusts by - lil- Industrial Operations, published hv tcring-out il.i -contaminant fronrthc the National Safety Council. air. The L`. S. Bureau of Mines has set.. up. performance standards.: for General ventilation 1-12. Where it is impossible, im practical. or too expensive to con trol dust entirely by local exhaust systems, general ventilation miK he used as a supplement or a substitute. It should be noted, however, that where local exhaust systems can be used, they will always do a better job than general ventilation. 143. General ventilation requires the introduction of enough clean air faint the outside to dilute the con taminated atmosphere to a safe level. This method requires larger volumes of air than local exhaust systems to accomplish the same conIrol. and will not be effective uni formly over a large room. It should be considered only when local ex haust systems require such assis tance. This is usually where the sources of dust tire widely dispersed anil each is small. 144. General room exhaust and supply fans must he carefully in dus: respirators and gives approval to respirators that meet these stand ards. It is important that a respirator - be used nnfy- for- -the particular dust- exposure for which it has been approved. 147. Alnough approved respira tors will give excellent protccion when properly lilted, they should be used only as supplements to Other, methods, of... control pr. lor short or occasional exposures and not as primary controls.-. .... |4S. Proper titling of a mechani cal tiller respirator to the face of the indiv idual is most important because a small space between the facepiece and the face will permit dustladen air to bypass ihe tiller. 149. Respirators must be in spected and cleaned daily. Filters should he replaced before they be come so plugged with dust as to seriously increase resistance to breathing. Proper tillers for replace ment should Iv available. stalled. Eddy currents, which will Medical program capacity, or serious pulmonary dis eases. -' 153. PerioJie physical examina tions. including chest X-rays, should be made of employees exposed to toxic dusts, fumes, and mists. Such checks can help liiid incipient cases of poisoning in which sympionis tire slight. :and 'the- X-rays -tan pick up early symptoms of lung condi tions. Suitable preventive measure* can then he it.ken. ' ''15-T.' Routine ' periodic '.clinical examinations, stipple cell count*, porphyrin determination*, and prop- periy evaluated blood and urine lead level measurements, are ptae- ticttl method* for checking em ployees exposed to lead. If unsafe exposures- are found, further- en vironmental control i* mandatory. Affected employees should. . of course, be given proper medical treatment. 155. Medical controls for em ployees who work with radioactive dusts must be more stringent than the medical control* for most dusts. An extensive bioassay sampling program is nearly alwavs required Other control measures 15b. Although tlw nto*t effective method of control is to prevent con tamination of workroom air anil tluis preveni inhalation of harmful interfere with local exhaust systems, must he avoided. Employees must I5D. An effective medical con trol program will help prevent not be exposed to excessive con centrations of dust as the dust-laden eases of occupational disease. Such a program can also serve as a cheek air moves away from the point of on the engineering controls hi cause generation, and sullicicnt makeup symptoms of exposure in a group air from the outside must be sup of workers will indicate a failure plied to the room to replace the air that nui-t be corrected. The extern that is exhausted. The location and of the medical program will depend design of the source of supply are upon the *eriou*ncs* of the expo important. It is becoming common practice to supply clean, tempered sure*. 151. An industrial hygiene pro air to the work /one lor controlled dilution. Wet methods i s u .. ......................... . l\ ..... .1 cram 'lion d parallel the medica1 prouram. Both are essential to pro tect the health of employees. 152. The piusical examination .- .. .. .. '. .. ' t-.-li-.l.- flgi,.,. 6 Tk- troliKogol `o-o orola-d Sr gr.rdmg hf<l eou- 9<n->o'rd dull -o l-o>-l I* o --II dof.n. d polk To p'--l d.iiv-- ,> ( I tko dull. IS- -Soul- k sod ; plott-H d. r**<U fhe* r- . . .. <!cw ........ f. . .1. - . <. . iltiNis. the important.-. of pcrxiinul hygiene dinuld not he overlooked. I lie periodic medical eliminations provide ;i good opportunity for invtruction of employees in various personal hygiene measures. 157. Gn)d washing facilities, clean lunchrooms, and clean work clothes can help prevent additional, even though minor, exposure to toxic materials. Also, contaminated work clothes should, not be taken home where- a toxic dust could contaminate the . home or; expose other members of-the family. These recommendations become manda tory where such materials as beryl lium and radioisotopes are handled. ' acknowihdgmIent1 ' I lie test of this data sheet, which re places Health Practices Pamphlet No. 4. was prepared hy the Health Conn liltee ol the Chemical Seelion. National Safety Council. I he content has Seen extensively reviewed by members of ihe National Safety Council, representatives of chapters of ihe .American Society of Safety J-.niiineers. medical authorities, and indtisinal hygienists. The data sheet has been ap proved for publication by the Publications Committee of the Industrial Conference. National Safety Council. Flfvrf 7.- In rim foundry, lace! friiovit.hoodt om Sntlotltd oir eocH italion having o thelUmolding irechint ond glue prett. AdeQuoi* mokeup o*r u' supplied from vft!lrtftng duct tituoted.betweenmolding mochinn ond proitet, `Courteiy Americon Fowndrymen't Society} ,, uisitOGSibur -' v. . Aciufent Prrreniion Manual h>r Imluuriul ()pertitiiin\. National Mutely Council. -125 N. Michigan A\e.. Chi cago J I. . . ... -.. .. . .. . ...... Antlirurmilicmit .-I'riorce Il,inl-('i>al \l:m-r\. C. S. Public Health lltillctin No. 221. U. S. Public Health Service. Washington 25. 15. C. 3 **.'5. Brjndt. A. I).. hnluuriul Health r'nvint'erinv. John Wiley and Sons. Inc... 4411 4th Avc.. New S ork 21. 1V4S. Data Sheets. National Safely Couiicil: . ' ` No. 4IIS. Antinionv amt h\ ( inn- ; ' 'Nt;. 1W. '.-Ir\etlit amt- //. tm>r- \'tait<- ('tunptmntl* . Herylliuui (in preparation) No. 5 12. Cailiniaai No. JJ.x l.int/ - ' ` No. 42'\ Muvne\iuin Nii. ,'IUi. A/t/ricurrr.\t- No. 2<>.n Mcrt ary No. 4S5. l iiunina: No. 2b". /.im iaiil y.incO.xitlr No. ,'S2. /.irriatiam /it Dreesen. W. C.. Dalla Valle. J. M.. I ilwards. T. I.. Miller. J. W.. and Say ers. R. R.. A Slmly W- Axbr\in\i< in llic dv/w/uv / c.vri/i- Imlaury. (J. S. Public Health Bulletin No. 24 1. I'. S. KOOLPADS cut the price you pay for sweat Sweat is one of the most expensive luxuries in modern industry. Production slows as workers stop frequently to wipe glasses, mop brows and gain relief from sweat. Cellulose sponge StaSafe KOOLPADS soak up that sweat (up to six times their own weight, in fact). Some workers even dampen KOOLPADS in water for refreshing coolness. KOOLPADS pay for themselves in keeping men on the job. KOOLPADS pay for themselves in safety. (Help solve the problem of blurred glasses and sweat-stung eyes.) KOOLPADS pay for themselves in worker comfort, which contributes to increased production. KOOLPADS pay for themselves in re-use. (Rinse in seconds and use again and again.) Write today for a free sample KOOLPAD STANDARD SAFETY EQUIPMENT COMPANY