Document gkG2RG3B7m4K1BparNQXx7da

FILE NAME: National Safety Council (NSC) DATE: 1965 DOC#: NSC195 DOCUMENT DESCRIPTION: NSC - National Safety Congress - Dust Hazards Related to Health 1965 A aliona/ S a fely Congress Mining Industry VYc are faced with the need t<i develop new techniques; new equipment ; and new thinking if we are to develop and produce the mineral materials which remain immedi ately available to us, let alone lind new deposits covered hy hundreds ol feet of overburden. Contrary to the situation which existed 51) years ago, there is, today, a real dearth of qualified candidates tor the jobs available in our industry. T h e re is an acvite lack of young people training for technical or super visory positions. The c l o s i n g of mining schools, due to a lack of students, is shock ing. J cannot help but attribute these con ditions to the unfortunate image which has been created. Our Nation is committed to assist new nations in their efforts to improve living standards and our industry is dedicated to do its part in meeting domestic needs as well. Neither of these objectives can be met unless we make a dramatic change in manpower availability. Competent technical skill- will be'needed to help the emerging countries develop and produce their resources as well as lind-ore-hodie- not readily appar ent from snriaee muni testations. Similar talents will he urgently needed at home if we are to maintain our own standards m living. As a result of these almost unprecedented demands, every e.ttort must he. made to present to the potential candidate fo r a natural resource career a true story o f the opIHirtunities that exist within our industry. Conservatives in the mining industry have lieen slow to recognize that a revolution h a s 11it our industry Science has been'let In the hack door with seeming reluctance. The min ing engineer is, too often, regarded as a doer rather than as a thinker, and little credit has iHtm given to the development of the mineral -eieuces. In modern mining one can see at least three distinct fields of scientific application which are rapidly becoming apparent. The first re q u ire s an approach from pure mathe matics and physics to rock mechanics and environmental engineering. The second re quires an approach from statistical mathe matics to valuation, control and economic engineering. T he third embraces the social sciences with applied physiology, ergonomics and even psychology invading the field. 6 All of these revolutionary ehan^l_ native, but be assured th at our national SO years ago van do little it n t d ^ woulida bue sce*rio<usly jeopardized willi provide a safe and stable working tf al products am! survival cotthl --we must not let another 100 years go by before effectively appraising the public and its political representatives of our industry's ment. W here our lathers designed jo .jtt such actions significance to national well-being, its oppor ported their workings hy shrewd J # though Agricola pointed up our ami experience, we can todayv anHd.g<m i-t**1 o*ve,r 4l1n vyee-air.=, aoo little prog ress qualitative knowledge; and ottr 5oij; Sttct been made in appraising the public add growing precision in numerical ,,,r importance to thei tion. to much less than "other minority With so m am ' obvioti: opportunity " that our voice is seldom heard or challengi . taring our industry, the J I M ?afohlcms considered in political circles. talent is at unco apparent. We musi Mm^ l iLj' ai ae n tSs of national minerals sitefuitiiitit- tunities, its challenges, its security, its true family environmental advantages, and its working conditions. You men in this accident prevention field, closely cooperating with industrial relations people, have laid a firm foundation and have built a sound structure. You have a m ar ketable product for America and the world. ml to our sons that these opportunity#^** too often made without painstaking ami that they are as ttilly chaHem-^l* --a. ^ analysis which under emcr- O u r job is now to sell ourselves. Only in this manner cun we hope to have men in anv "Incli arc publicized m the e x * c i r c u m s t a n c e s can dangerously deplete .-op u-hi .tied lields ot space or mineral supplies without feasible lion. We must emphasize that ultimate i-ilv is not the reward lor a minernU and this is aUestevl to hy the for replacement. { Mimot help but repeat again aud again the mines and minerals available to avert national disaster and meet our world com mitments to bring an enduring peace to a mineral-hungry world. have made. We must point out tta mining communities oiler families `'FI nitics to develop under die mihienn* bvM academic, medical, religious, and recreational lavilitivs. * ThU is not a new problem, but '-I DUST HAZARDS RELATED TO HEALTH mvucv i-N more acute than when Agri* u? 155o, reported as follow*: ^ " Many persons hold the opinion : inetais industries are fortuitous ain* By R O B E R T L. HARRIS, JR. Field Investigations Section, A b a te m e n t B ra n c h , D ivision of A ir P ollution, U.S. Public H ealth Service the occnpadon is (iu: of the >ortai" k . ... . and altogether ti business requirittc J 1'" ,,vrral11 problem ot dust hazards ic- imich -kill a labour. But as for r:-WH I" health ts only part.ally solved M u c h when I rellecl caretullv upon ib Unlearned m the past and put to use ; points one bv one, it appears t u -.| ** * t0 be douc' U a' complex otherwise. For the miner .mist l o w lH * W*1"* r e m a i n require oomhmed respirator)- system copes with dust particles which are inhaled, some of the aspects of sampling to measure degree of exposure, and some, of the etlcets on health which may result from excessive exposures. greatest skill in Ins work. . " the ,fie tls ot rngmecrtng, phys.es. ., , ... , , I femlitry, toxicology, physiology, pathology, Modern nations, like man, do not "' | ^ Hwdicinc bread alone, but bv the CYvrgrowit'v sumption of metals for tools and ^ 'W link, or relationship, between hazards products. Nations desperate for these r* W "'cir adverse ehects on health is the often take ill-cnm-eived measures to o exposures to predict their bio- them. A hungry w.irhl is not a I"-* N * Beets. Precise and specihc means ot world and tlie world is hungry K 4 '"trnt would permit accurate predictions with which to produce. iff an<1 economical and cllective con- W\ ee muibst, thj ecrecftorce,. ,hbe in a v,. , . hazards. Completely sadstacUwy assist in the orderly location and : $><tu>i| for the assessment ot exposures to ment of new ore deposits wherever l . itc not -yet -proved or in use. mav ntvur in the world. O nh a well*iT r i f definition of the ruuse-and-eltect eadre of skills, available to mir nic'ifyrNrki ^M idiips in the pneumoconises is espe- will allow our industry to make sin*11* difficult, b e c a u s e disease may first eoutriimtioiis to world stability. * number of y e a r s after initial The Mature of Posts Dust particles which are hazardous to health when inhaled are invi-ihle to the un aided eye. T he smallest particles ordinarily seen without magnifying devices are about .10 or -10 microns in size; those which are hazardous are ordinarily smaller than 5 or 10 microns. (1 m i c r o n is approximately 1/25,000 inch.) Small particles, those in the range of 1mteron diameter, behave in air much differ ently than do partirles which are large enough to he seen. These small particles, once airborne, remain in the air for long jieriotls of time. F or example, quartz par ticles o f 1-micron diameter settle only 0.01 The Russians, like the Roman ol foot per minute in still air. In turbulent air, day, put political prisoners and discussion reviews some of the rcla- if sedimentation is the only mechanism of peoples in their mines. God grant between dust hazards and health by removal, half of the 1-micron quartz par Nation '.vi!! never be faced the nature of dust, the way the ticles in a 7-foot-high space would still be  I'M,5 X u tio m il S u f c t y C ,m,,r,'ss Minina Industry airborne 8 hours after generation of ilust The coal -gems to break along *1 IJi Of 3 microns equivalent size hail stoi>peil. A l- m irro u quartz particle * ` for the most part, m tho upper .projected into still air with an initial velocity high impurity or high ash content, ^ ZM " Srttory system, that is tin* nasal cavity, J of 10,000 feet per minute (about 100 miles the 'lust generated, the particles ui brondiial tubes, and other per hour) will lose its momentum in a tend to be larger than those of |lt i ^trachea, thwehebreas particles 2 microns in distance o f 0.01 inch and will thereafter settle or move with air currents. 1'articles minerals, 4 bv-e data illustrate that incite ies and particle dynamics have cite size are deposited about equally 11te eumposithm o( dusts. * ? * ! respiratory system ;mtl in the smaller than about J micron (0.3 micron or pulmonary air s|;tces. Particles tor quartz, 0.7 micron for coal) in diameter A'I'spinitiiry X y stK-in | micron in size are deposited more arc affected more by forces of diffusion than by the force of gravity. At ordinary tempera 1he respiratory surface m th ^.,,rttly itl the alveolar spaces than else- tures, the llrowuian displacement in air ot normal man ranges from c C, mtd sentially none are collected in the A articles o f (his size w ab o u t the tame as squale loot at rest t* about 1000 lg| respiratory system. their Stokes settling velocity, about 1 uiillimeter per minute. Thus, tli d> nantie citar at deepest inspiration. The memlirmw bough the respiratory system is a very ratini; the alveolar air spare from cimila^ *mit dust collector, all of the hist colblood may bo only one or two celU m tu} acteristies of small particle ti re such that ness. In the course of an .8-hour likd ti not retained. The system has a once airborne, for all practical purposes, jj,l> efficient mechanism for removing the they move with air currents. Sedimentation moderate work, a man breathes .ilnt A gj|M|<t] dust. For example, during 30 years has a negligible elfeet upon dust pnrtich concentrations in normal work situaiioiis cubic fret <>! air. Contrast the tora-.l \ottJ i *tfk a coal miner may inhale and collect tinti eNpnsure of the large dvln.ur <ItW| f til respiratory system 10 to 15 pounds of and the kinetic energy thee Io-i--s al uuu eratioii is quickh lis-ipated. -u r la te with the ambient air ini'lit rf, hut [ter this 30 years, his lungs may the skin, which has some 20 sqti.tn- i..i J ..till only 0.1 to 0.15 pound of ilust. The surface and a thickness measured <m -r-4 J iitutii'y of removal is thus in the order of Partirle -i/e is ;dso importuni in matter- meters. It is evident that the lung - t'it * (sncllt. involvin^ ilio compaitimi ot dust . 1hi-t pro. dueed hv 1r i l i n o r mu-bin-: r-i'k dot hv far the most extensive ami inti!' contact ttf the b o d y w i t h tin- .ml' tw primary mechanism of elearauee in nccc--arilv bave ilio -urne c-mp<>-nion .ilinn-piicre. 1 tt|,|>rr respiratory system is eiliary action. sample of ilio parent rock. K 'on in ftfl'C Th, rC'i>tr;iiiJiy tract m mar irtpiratory tract, from the epiglottis to which has Iuri ino an i*' rne ilio -mali P a tirios nino Micecssively fro m the tracliea a ...ft' . i*ttllil):tl bronchioles, is lined willt cells --si minute hair-like t v o c e - s e s called ll.UC Ct tlllpi .-IH' 'Il Ul VVia-m ir ilio largor idii'S, l'Im o Uinds o -ampli host rock, -etiled fusi, ami airi >rno du m H/0 million u h im ate b r a n c h e J.'. Jm Tlir cilia, by continuous whip-hl-c mo- branches term inate in some 5UU unii - 't'l'e a blanket of niucoiK-like tltti<I >acs, or alveoli. T h e cross secii.'ii a ** " e r e obtained from euch <.t dille h 'rari >i bf fiR'ia/ mines. */'\vn fractiai- ,i tho Settle tr a c h e a is about 2 square centiiinirn, # the combined cross >vciiun< of .'In * *'W Upward on the surfaces of the air stf'Krt. This blanket carries dust particles dust sample: s w e r e a n a l y z e d ; one frac tion ducts, which handle about the -amc -d "llirr foreign material upward and out contained all p articles w hich pa --e d through d tint Kipiratory tract to he swallowed. ot air, are about 8,000 square iTniiHtfiW a uJu-mo-h screen ( --825 inc-h i ruction), M *cei in the alveolar spaces do not have lie o th e r c em m iicd only parlicies mailer J lie aerodynam ic b e h a v i o r "f Jmiit. ** The primary clearance mechanism here than a bout 5 -m icro n s 'h u m e u r ( 5 fi />;*- a r k s with -izt*. dvnsttv, ami sh.ijtf i'tW * (duKUCytosis. Phagocytes are cells which l io n ). T h e airbeme amples v t aki 'il well -inn <it ilust tivptsittun in tiiv 11 I'' t*-"; foreign materials such as dust par- low nstream i m m the points of g. eneration -yslvm is sinqihlivil b y t h e iiiin 'i'l * |heat cells appear in the tings, possi- to perm it l a r y e particle- to -i-ttle p r io r p "v'luivalrnt -izu" of articles, ''lit- runA* hy dliengaging from the surface lining, >ampbn^. The.-e results indicate -izv ! a 1'articlv is the dianivu r 1 > rate with thei r hurdeiis of foreign cerea mm free silica c o n te n t w ith deemrea-m ; p a r t i d density -ht'fc which has the -aim' ......*** tailing v c l t i c i t v in still air a- 'I''** either to the pulmonary lymph size. " nil of outward to the ciliated air pas- 1trii t ic Ic. wt 1*, where they are carried awav hv the Data from -ume mai mines -how more ash in airborne dust tlrau in die coal being T h e re sp irato ry tract, with ilbranches and t o r t u o u s pa-sag'" 'Miy action. it kf Hsutc the efficiency ot lung clearance mined. In the airborne dust from these highly eltieient ilust collector, .--iiiu dh ; fcfftot, a small decrease in it may result mines, the sample fractious containing only particles of small size have a lower per- parlicies g r e a te r than 4 o r 5 111111'" ' ' 'I" '* lent size w hich enter the respiratitiv *>**(? |he#t increase in the amount of material ^uns' Several oliservations cenlage of tr e e silica than do the tractions a re ilcpositoi in it. About half 1 ('""P" e ., " " *rtnce with lung clearance have with particles o f larger size., Lor example, the fraction containing only particles smaller 1-micron et|tiivalent size apjx'ar I to P .sited and the other halt cxhalf'l I* ^ * 0 " The efficiency of lung clearance .HIM# than 5 microns me m 2 percent freo sites of de[H)sition in the system arc tl I bI mtj decrease with increasing lung silica, w hereas the gross airborne sample for various sizes. u Irritant gases have been shown . f Or stop ciliary action in animals. may contain up to 20 percent. Some studies indicate that particle! which appear to be toxic to 8 phaj*i c\tvs rcilucc tlu ir vifvci i\ viu-hS in rciiuiva) "i inah-ria! iron) ihv pulmonary >pavc>. T b r nurbaniMU ui puliihiiiary tiel>ositit)n and clcaraficc (Jcsciat*, and uudoubtcdly will receive, a .qreal deal more study- htxt Samf'linij Any program for control or reduction "i exposures to dust requires a means of asses sing exiKi-ures. Since the etit*]oy;ies of some occupational diseases, particularly the pnenmocuui'>>es, arc not fully known, it is n'l possible to deiiue all the characteristics that contribute to the toxiciues or biologic eliects of dust. All of flic sampling methods used in diiVereut t>arts of the world if*r e^iimatm.: exposures to miucrai du>ts are empirical. None is an absolute method which will \ield data from which the hygienic >i:auificauci` of ex])osures can he precisely judued. i n tlie Un i t e d States, the Ame r i c an f *nf erence o f Uover mnct na! i ndu- t r i al H.veienists pr omul ga t es d'hre^iiold l.imit \ '. dinf or toxic mat eri al - t or u-e h> indu-triai li>.i;ieni'i- as euitie- in drvi-inu cdil iol : occupational expo-tires. T h r csiioId i.ueu Val ues have been <Ieveh<(H<l for a n u m] `tr ol toxic dusts. The !'l irc-i ii *ii 1 l.imit f or d u - t - with - \-teinic t "\ i f i t i e - . iead --r cadmium, for example, are i.rduiariiy <\ prex^etl jn mas s units, i.e., in m i l b u r a m- \x-v cubic meter of air. Sampling for such materirds may he by tiller *r other means which collect all ot the airborne material. The T h r e s h o l d Inna! Values for pneumoconiosis-producin'.; min eral dusts, on the other band, are expressed in terms of particle count; the customary unit of concentration is millions 01 particles per cubic foot of air imppef). The Threshold Limit \hdues for mineral dusts can lie used to judye only data yielded bv a standard procedure of itnpinyer -amplim; in liquid medium and lh;htlield microscojiie countiiie; of the collected dust. I he Threshold Limit Values for mineral dmt> cannot be applied to data from other particle count methods of sampling. 'Hie standard method of impinycr sampling and coiintiiiy aas prt`sente<l in !bd2 at a meeting of the National Conference ot tmvornmental Industrial Hygienists. Because the method is empirical, it must be followed closely by all us users if data obtained by one person are to be comparable to those 9 19(>5 :\tiliiinal S u jc ly Congress Mining Industry obtained by mother. Even then, variables in sampling ami counting within the method as it is described may permit two investi gators, both applying the method skillfully and conscientiously, to obtain ijuite different results to represent the same environment. Sampling m ay h a v e dilferent purposes, which merit employing dilferent techniques. 1hese generally fall into two major cate gories: (1) sampling for engineering sur veillance, testing, or control and (2) sam pling for health research or epidemiologic purposes. Engineering applications of sampling may include locating s o u r c e s of contamination, monitoring performance of environmental control systems, or doing research in such problems as c o l l e c t i o n efficiencies of air cleaners. A sampling program for engineer ing purposes should be designed to yield the specific ' information desired. For example, one might need only a single sample before and mother liter ;i change in ventilation to determine whether the change has had the desired effect. Hygienic applications m sampling, on the other hand, may he directed at predicting the health elfects of an exposure by compar ing sampling results with hygienic guides, determining compliance with health Codes or regulations, or research to deline is prcciselv is possible environmental factors fo r c o m parison with observed medical effects. In the latter case, sampling may provide the basis for development or rehnement of hy gienic guides such as T h r e s h o l d L im it Values. Sampling lor atmospheric particulates pre sents ipiite different from those of sampling lor gases and v;q>ors. ti.ases uni vapor-., when inhaled, can penetrate all iirtions of the pulmonary system .and follow the l.iu. of distribution hv ililtusiou .and absorption. The sizes and densities of particles, on the other hand, are major inlluences in deter mining the sites it w h i c h they will be deposited in the pulmonary system. Since the effects produced by particles trapped in the nasal passages or deposited in the ciliated portions of the pulmonary system may he ipiite dilferent from those of particles which are deposited deeper in the pulmonary sys tem, size-selective sampling is generating increasing in t e r e s t a m o n g i n d u s tr i a l hygienists. At the 1'iicumoconiosis Conference Johannesburg, South Africa, in 1959, n, experts in pneumoconiosis from all over 3, world participated, it was concluded tluj the light of present available evidence fc best single parameter to measure in the of coal dust, is the mass concentrati,,, 4 respirable dust, and in the case m .,,,,t du-t, is the surface area of the rcspu,ti dust.'' The respirable fraction of a dust dijwas then defined as ill particles smaller 11 1 micron, half of those of 5 intermit, m* none of those 7 microns or larger in oimu lent diameter. Sampling devices ban- I*, developed to sample Ibis respirable Ir.i.ti.* They either reject particles too l.unr 1, penetrate to the deeper portions of the 1, or collect larger particles in a prco.ui,|^ so that the respirable portion can be cnllr,|<4 separately for weighing and anali-i- The n'Mitts oL sampling for lu-t -noli <loviiT.s. either for ^rav'imeirif <1-m nation* or tor determination of oimp.'.n.i cannot lc interpreted l>y use of mir l luxdiold Limit Values or siniti.u t>r judein^ exposure*. Such sampling, ever, may represent a sensitive ukiS predicting the disease-producing poioiiuM exposures to mineral dust. I he devices miyht also he um-1 i>* tineuish the portion of an expn>urr tn i** <1u >ts which results from pulmoii.u v .hof ti>11 and the portion which result let! ah^orptioti th r o u g h the yastroinio'tm.ii ** Such samplers are worthy of "hide ami use than they now recriw `it ifc* e< uiitry. Sont i i . f f c i t s frt>m l\.vf'i>sun' to / 'to/ The two types of occupational which may result from exposure to dn*t *** the pueumoeonioxes and cliemical Hit*'*"* lion*. lhieuniiH'oninses are di"v:oi'i ^ Iimys which result from exposure *' ( hemical into xications are not limitrM"*N lunurs and a re characterized by I**-'* '* *** tematic effects, w hich result Mein t*1#' to, or absorption of, toxic material. The most common ^ silicosis, coal workers pncunmcniH*1* . * ashestosis. These diseases are cliaMitt ^ by pulmonary fibrosis, which is chest X -ray examination, and by t unction progresses. , 1963 the Public Health Service pubjjrtlarepoH by the Service and the lluroaii ^lines on a study of silicosis in the. metal Jpg industry.3 In this study some 14,000 ^ e rs at some 50 metal mines were exd. X-ray examinations showed ;i crude rtlence of 3.4 percent silicosis among the sjy population. The prevalence of silicosis *#lg underground workers was about twice 4tamong surface workers, 4 percent versus >percent. U n d e r g r o u n d face workers touted an overall crude prevalence of about potent silicosis. In a further breakdown of these data the ,M for face workers aerordittg to years <Ork were: less than 10 years of work. t| percent silicosis; 10 to 20 years, 2.5 WHt; 20 to 30 years, 11 percent; and V than 30 years, 26 percent. ( lili reasonable to suspect that older men Irred higher dust exposures in earlier it* than are common in the industry now. matter was examined in some degree i winparing silicosis rates among men w ho t-tked in metal mines at some time prior icycar 1935 with rates a m o n g men wlm "tUil only after that year. The examinati showed 8 percent silicu-i- among men ` ill 10 to 15 years of total work in metal -dug, but with some work prior to 1945. 'tig men with all of their work experiM after 1935, 20 to 25 years of work " Iticcd a silicosis rate of 7 to 8 percent. Tiltil, the earlier exposures seem to have jxillftl in the 8 percent rate of sil-o-is with ^*`il 10 years less work experience than *! later exposure. "i May of this year, the Hivi-ion (,f Occit'``'iwl Health, Public Health Service, ;m''iinl the results of a study of coal "ft* pneumoconiosis among a sample of itwMCliian bituminous coal miners. The maldice of the disease among the active '"*'01 examined is about 10 percent; among 'ftl ltd other inactive miners examined flt is almost 20 percent. More than 20 of active miners in the 55- to 64 age affected. The duration ot exposure " j * TM be very significant, the prevalence Increase markedly among groups fhan 20 years of underground Jem of pneumoconioses is far Control of the disease depends of exposure. All presently 10 available knowledge should he applied toward control, hut this is not sulncient to asMire that the disease can he economically con trolled in all cases. Additional medical and engineering studies are needed to find the most reasonable, economical, and sure means of control. Relatively few problems of intoxications from dust arise in actual mining operations, hut they arc not ini rci|Ucnt in milling and smelting operations. The effects of absorp tion of toxic dust are extremely variable. Effects may range from muscle and joint pain from antimony compounds to chill- and fever from zinc fumes. Sonic chromium compounds may cause lung cancers and perforation of the nasal septum; manga nese may cause staggering, high stepping, and other gait disturbances; and mercury may cause irritability and emotional insta bility. In contrast to the pneumoconioses, which do not regress with anv known treatment, most chemical intoxications respond luvorably to medical treatment and cessation ol exposure. S uiniiiiiry I [liman lungs are ,-i/r-seiective dust col lectors. Only relatively small particles, gen erally those le-s than 5 microns in diameter, reach the alveolar spaces. Such small par ticles mow- with the air currents; they settle very slowly in still air. and even when thrown into the air with high velocity they travel through the air only a short distance. T he lungs have a very large surface. 590 to 1,009 -.quart- feet of w r y delicate tissue. This surface is exposed to contaminants in the air breathed. The lungs hav- good defettses a g a i n s t particulate.-: when unim paired. these clearance mechanisms remove about 90 percent of the insoluble dust de posited in the lungs. The control of exposures to du-t requires a means of assessing du-t concentrations in the air. Methods u-cd for sampling and quantitating mineral dust concentrations ire empirical, and results viewed by one method cannot be judged by standards based on another. Even with a single method, for ex ample, the impingcr sampling and counting mcthixl, differences in application can cause differences in r e s u l t s o b t a i n e d by t wo investigators. 11