Document MMJyNrrm89Y1BjOZRkO8owpna

United States Department of the Interior Geological Survey K. L CHEETHAM JUL30S84 MARKETING SERVICES A Survey of Asbestos-related Disease in Trades and Mining Occupations and In Factory and Mining Communities as a Means of Predicting Health Risks of Non.Qccupational Uposure to Fibrous Minerals* by Malcolm Ross Open-File Report 82-745 This report Is preliminary and has not been reviewed for conformity with u. S. Geological Survey editorial standards and stratigraphic nomenclature. 1952 ***999* ABSTRACT: A review which Is based on thirty six published epidemiological studies Is given of the disease patterns that have developed among Industrial workers, miners, and millers who were exposed to dusts of one or more of the conrnercial asbestos minerals or to dusts from minerals perceived to be asbestos*like. Health data Is also reviewed for those who were exposed to asbestos dusts in a non-occupational setting. From the published reports it Is clear that there are very significant differences in the health effects of the several asbestos or asbestos-1 ike minerals. Of the conrnercial asbestos utilized In the united States about 951 has been chrysotlle or "white" asbestos, about 21 amoslte or "brown" asbestos, and about 21 crocldolite or "blue* asbestos. The common white asbestos has had the least effect on those occupationally exposed whereas blue asbestos has had the most effect. Oesplte the wide dissemination of white asbestos In our environment; In schools, homes, public buildings, brake lining emissions, etc., there Is no evidence that the very frequent non occupational exposures to this form of asbestos has caused any harm. On the other hand, nonoccupatlonal exposure to blue asbestos has been conclusively proven to have caused significant mortality. The different health effects of the various forms of asbestos require different regulatory responses and remedial actions. INTRODUCTION The Problem The widespread use of amphlbole and serpentine asbestosl/ by Industrial society for such Items as service In brake and clutch facings, electrical and heat Insulation, fireproofing materials, cement water pipe, tiles, filters, packings, and construction materials, has contributed greatly to human safety and convenience. Yet, while our society was accruing these very tangible benefits, many asbestos workers were dying of asbes tosl s, lung cancer, and mesothelioma. The hazards of certain forms of asbestos under certain conditions have been so great that several countries have taken extraordinary actions to greatly reduce or even ban their use. Recent experiments with animals demonstrate that the commercial asbes os minerals as well as other fibrous materials can cause tumors to form whun the fibrous particles are Implanted within the pleura. These experiments have convinced some health specialists that asbestos-related diseases can be caused by many types of elongate particles; the mineral type according to these health specialists, is not the Important factor In the etiology of disease, but rather the size and shape of the particles which enter the human body. The question now before the World's health and regulatory establishments Is whether the hazards of asbestos outweigh the benefits. Should the asbestos minerals and perhaps other asbestos-like minerals be banned from use? Minerals belonging to the amphlbole group are particularly Important In this regard for they are ubiquitous and commonly have crystal line habits which are considered by ?ome to be asbestos-like. The Dilemma The concern for human health, tie great usefulness of many asbestcs products, the appearance of asbestos minerals or asbestos-like minerals In the natural background and In many kinds of mining operations, and the un certainty of the exact health effect? of different kinds of minerals, different mineral particle sizes, ami different mineral dust concentrations combine to present a formidable problem to minerals scientists, the 1/At present, the most widely used definition of asbestos In the Unite* States, Is from the not ce of proposd rule-making for "Occupational E posure to Asbestos" published m the Federal Register (Oct. 9, 19*5, p. 4765', 47660) by the U.S. Occupational Sare'y and Health Admlnlstr tlon {OS HA. In this notice, the naturally occurring amphlbole minerals moslte, crocldollte, anthophyl11te, tramollte, and actlnollte and tie serpentl >e mineral chrysotlle are classified as asbestos If the Individual crysta lltes or crystal fragments have the following dimensions: length greater thin 5 micrometers, maximum diameter less than S micrometers, and a length.rodlameter ratio of 3 or greater. Any iroduct containing an^ of these minerals In this size range is also diflned as asbestos. 1 0419989 minerals Industries, and legal and health professionals. Must the use of all commercial asbestos be stopped? Must all mine dusts containing such particles be controlled to the lowest feasible levels and wastes from those mines be considered toxic and thus isolated from surrounding air and water? Must all asbestos be eliminated from our drinking water, our schools, and our public buildings? Mist we cease to use asbestos In brake linings, cement water pipe, and structural building materials? Must even low levels of non-occupatlonal exposure t> asbestos or asbestos-like materials be avoided at any cost? In order to obtain an Insight thit will enable us to Intelligently address these questions I will review the role of asbestos in the world economy, the Important geological occurrences of commercial asbestos, give estimates of asbestos-related mortality In the Ini ted States In the recent past, and document the Incidence of asbestos-related disease In the trades occupations, the mining and milling occupations, aid in those non-occupattonally exposed to asbestos or asbestos-like minerals. As we will see, the six asbestos minerals used In commerce are not Ideitlcal In their crystal structure, chemical composition, abundance, and geologic occurrence; nor do the different asbestos dusts have the same Impact 01 human health. Instead of treating all asbestos minerals as equally poteit carcinogens (apparently the prevailing opinion In the United States) each ml leral should be examined on Its own merits and demerits with regard to Its usefulness to society and Its potential to cause disease. dl9986 ASBESTOS IN THE WORLD ECONOMY Early Beginnings Whereas the general use of asbestos In international commerce dates only to the late 19th century, Its utility In human culture goes back to at least 2500 B.C. Archeological studies (Europaeus-Ayrapaa, 1930) show that the Inhabitants of the Lake Juojarvl region of East Finland knew how to strengthen earthenware pots and cooking utensils with anthophyllite asbestos. This asbestos probably came from the same areas where It has be<n commercially exploited in recent times. Until recently, however, most othtr uses of asbestos were trivial ; such as Its fabrication Into such curio* Itles as cremation cloth, tablecloths, lamp wicks, and purses. Even well into the last century, asbestos could not be regarded as a product of commerce unless one included such endeavors as the small Industry developed In Russia during the rule of Peter the Great vrfiere chrysotlle asbestos from the Urals was used for a short period of time in the production of textile*. In the 1860's and 1870's, the market for asbestos products rapidly changed - probably for three reasons; tne need for Insulation for the new steam technology, the formation of an International trading company of Italian and English entrepreneurs, and the reopening of the chrysotlle asbestos deposits of northern Italy and simultaneous exploitation of the vast chrysotlle resources In Quebec. The supply for the first time was ample, the market was ready. The Modern Industry The reopening of the asbestos deposits of northern Italy, deposit which had been worked as far back as Roman times, marked the beginning of the modern asbestos Industry. By 1890, the asbestos Industry was full blown, with hundreds of applications being Introduced (Jones, 1890); by the turn of the century the large South African crocldollte deposits had been opened up and the Russian deposits In the Urals were once again producing In large quantity. Within a few years, the amoslte deposits of the Transvaal would be exploited. From the time of the first recorded use of asbestos by Stone Age man to 1900 the total world production of all types of fiber was probably about 200.000 metric tonnes, certainly no more than 300,000 tonnes. Of this 150.000 tonnes came from Quebec. By 1980 more than 100 million tonnes of asbestos hed been mined throughout the world; of this more than 90 percent was chrysotlle and more than 5 percent crocldollte and amoslte. Nearly 40 million tonnes of this total World production was chrysoMle mined In Quebec Province near the towns of Thetford Mines and Asbest*s. Total production of anthophyllite asbestos to date Is probably no more than 400.000 tonnes; 350,000 tonnes being produced by Finland alone. Production of tremollte asbestos has been sporadic and It has been mined In various parts of the World for short periods of time. Total production to date for this form of asbestos Is probably no more than a few thousand tonnes. Commercial exploitation of actlnollte asbestos is practically unknown. 0419987 ^ The World asbestos production for 1978 Is given In Table 1. Russia leads with 46.1 percent and Canada Is second with 28.9 percent of the world output. Both countries mine only chrysotlle asbestos and most of the fiber comes from the Urals and Quebec. The third leading asbestos producer Is the Republic of South Africa (7.1 percent); the asbestos ore consists of amosite. crocldollte, and chrysotlle. These three countries furnished 82.1 percent of the World's asbestos In 1978. The other countries listed In Table 1 produce mostly chrysotlle. COMMERCIAL ASBESTOS The Asbestos Minerals Standard references published over the past 50 years usually list six forms of commercial asbestos; the amp'll bole varieties are amosite, crocidolite, anthophylllte, tremollte, and actlnolite, the serpentine variety Is chrysotlle. A detailed understandlng of the chemistry and crystal structures of these asbestos minerals postdate their discoveries; thus some of the older literature can be confusing with regard to mineral Identifications. Chrysotlle, Mg3Sl20s(0H)4, one of the three common polymorphs of serpentine Is generally fibrous although non fibrous varieties are known. About 90 percent of the past and about 95 pe cent of the present World production of asbestos was or Is the chrysot le form. Amosite Is the very rare asbestlform vaiety of grunerlte amphlbole, (Fe ,Mg)7S1 822(h)2 ; varietal nne Is d-rived from the word Amosa - an acronym for the company "Asbestos lines o South Africa" (Hal 1 , 1918, p. 13-14). This valuable commercial isbesto Is mined only In the Transvaal Province of South Africa. Crocldollte Is the asbestl form virlety >f rlebecklte amphlbole. Ideally ^(Fe2*.Mg^Fe and ha. been mined in only four localities; In the Transvaal and Cape Povlnces of South Africa, In the Hammersley Range area of Western Australia, and In the Cochabamba area of Bolivia. Only the South African mines are still active. The only other form of amphlbole asbestos that has been mined commer cially on a significant scale Is anthophyl 1 ite, (Mg.Fe)7S1g022(OH)2, from the Paakklla area of East Finland. With the Finnish mines now closed there Is now very little anthophylllte asbestos production anywhere in the World. There are numerous reports of minor occurrences of tremollte asbestos, Ca2Mg5S1g092(0H)2, and relatively few reports of occurrences of actlnolite asbestos, Ca2(Fe,Mg)5$ifl022(0H)2. Tramollti and actlnolite asbestos are now, as they have been in the past, of little economic Importance. The Important Geological Occurrences of Commercial Asbestos Many minerals, Including the ampilboles and some serpentines, are described variously as fibrous, asbestl form, aclcular, filiform, prismatic; these terms suggest an elongate habit. Although such minerals are extremely 4A 0619988 Table 1. World asbestos production In 1978 (Clifton, 1979) Fiber Locality Chrysotlle North America Canada United States South America Argentina 8raz11 Europe Bulgaria Italy U.S.S.R. Yugoslavia Africa Zimbabwe South Africa Swaziland other Asia China Cyprus Indi a Japan Korea Taiwan Turkey Oceania Australia (World chrysotlle total; Crocldolite South Africa Awoslte South Africa Production (In thousands of metric tonnes) 1620 93 1 100 21 162 2382 10 210 118 48 1 21 n 37 21 7 7 1 10 58 5317 210 71 0619989 48 common. In only relatively few places do they have physical and chemical p>opert1es suitable to be valuable as commercial asbestos. Locally, amphlbole minerals may show an asbestfform habit, for example In vein fillings and In areas of secondary alteration, but usually they do not appear In sufficient quantity to be profitably exploited. Deposits of commercial asbestos are found In four types of rocks: (I) - alpine-type ultramaflc rocks Including ophlolltes (chrysotlle, anthophylllte, and tremollte), (II) - strati form ultramaflc Intrusions (chrysotlle and tremollte), (III) - serpentlnlzed limestone (chrysotlle), and (IV) - banded Ironstones (amoslte and crocidollte). Type I deposits are by far the most Important and probably account for more than 85 percent of the asbestos ever mined. The most Important Type I deposits are those of Quebec and the Urals. Type II deposits are found mostly in South Africa, Swaziland and Zimbabwe. These furnish mostly chrysotlle asbestos. Type III deposits are small; the most notable of these are located In Slobe, Arizona and In the Carolina area of the Transvaal Province of South Africa. Type IV deposits are found only In the Precamirlan banded Ironstones of the Transvaal and Cape Provinces of South Africa anl of Western Australia. Only the South African deposits are still In production. A complete review of the geological occurrences of commercial isbestos Is given by Ross (1981). HEALTH HAZARDS OF ASBESTOS Diseases Related to Asbestos Exposure Three principal diseases are related to exposure to one or more of the commercial asbestos minerals. These are: (1) lung cancer which Includes cancer of the trachea, bronchus, and lung proper; (2) mesothelioma, a cancer of the pleural and peritoneal membranes which Invest the lung and abdominal cavities, respectively; am (3) asbestosls, a diffuse Interstitld fibrosis of the lung tissue often leading after long exposure to severe loss of lung function and respirator} failure. The occurrence of lung cancer in asbestos workers Is also complicated by the association with cigarette smoking which leads to considerable difficulty In assigning relative risks of asbestos exposure to smokers. Mesothelioma, a disease which Is usually fetal In one to two years after diagnosis, is rare, accounting for less than 300 deaths per year In the United States and Canada. Some epidemiological studies suggest that asbestos workers may suffer excess cancer of the digestive tract (Sellkoff and Lee, 1978); other studies do not support this conclusion (McDonald and McDonald, 198(1; Meurman et al., 1974; Rublno et al., 1979; Nicholson et al., 1979). Some question still exists then as to the role played by asbestos In the etiology of digestive tract cancers. Recklake (1976), Selikoff and Lee (1978), and Simpson (1979) give a complete review of the subject of asbestos and disease. Particle size and shape appear to be the factors controlling whether mineral particles enter and remain In the lung or are removed from the lung after entering. Particles such as asbestos fibers which have diameters 5 *4**990 greater thin approximately 5 iff cannot enter the bronchial airways, those having smaller diameters do. Particles having diameters less than 1.5 i/n are particularly dangerous for they can penetrate to the smaller bronchioles and even to the alveolar sacs (Davis, 1981). Host particles which enter the upper respiratory tract (the malnstem, bronchi, and bronchioles) are quickly and effectively removed by the mucoclIllary escalator. A second lung clearance mechanism operates In the lower respiratory tract (the respiratory bronchioles and alveoli). Here, pulmonary macrophages engulf the foreign particles (phagocytosis) and then: (1) move to the upper respiratory tract to where the mucociliary escalator Is operative or (2) move through the alveolar wall Into the interstltlum and eventually to the lymph channels. Asbestos fibers which are longer than approximately ID wn are not readily phagocytlzed by the macrophage cells and thus tend to remain in the lower respiratory tract or they ma/ penetrate the pleural membrane and enter the interpleural space. Asbestoils may occur when such fibers remain In the lung parenchyma for lengthy periods of time. The asbestos fibers can stimulate deposition of excess 1ntrst1al collagen and retlculln fibers. This causes the alveolar septa to beccne thickened with ensuing Impairment of oxygen uptake (Davis, 1981). Long-term residency of fibers In the lung and pleura may also Induce lung cancer and mesothelioma; the mechanisms by tftich this takes place are far from being understood. As will be described later, pleural cancer seams to be induced by crocidolite asbestos but not by chrysotlle or anthophylllte asbestos. Lung cancer Is caused by chrysotlle, anthyophylllte, amosltf , and crocidolite asbestos; particularly In asbestos workers who smoke cigarettes. Two completely different substances, asbestos and cigarette smoke, combine to produce a very significant risk to those who have been heavily exposed to asbestos dusts. Generally, asbestos-related diseases appear in asbestos workers only after many years have elapsed since first exposure. A significant Increase in the lung cancer death rate appears 10 to 14 years after first exposure and peaks at 30 to 35 years. The mesothelioma death rate becomes significant 20 years after first exposure but continues to climb even after 45 years have elapsed. The asbestosls death rate becomes significant 15 to 20 years after first exposure and apparently peaks at 40 to 45 years (Sellkoff et al., 1980a). Epidemiology Before considering the mortality studies of the various occupationil groups exposed to asbestos, we should briefly consider the role the thr?e Important types of asbestos (amoslte, :rocidol1te, and chrysotlle) play'd in the commerce of North America and Etrope, the areas where the major epldemllogical studies of asbestos wor ers were made. 6 oi In North America, chrysotlle entered the market In large quantities early In this century. Crocldollte was apparently first used In the United States In 1912 when 9 tonnes were Imported, but It was not until World War ! that its use for high temperature insulation became established - particularly In the ship building Industry. By 1930, 35,000 tonnes of crude crocl dollte fiber had been Imported Into the United States. Import statistics for crude crocldollte asbestos from South Africa Into the United States are given in Tables 2a and 2b. Large amounts of manufactured goods containing crocidollte were also Imported hut tonnage estimates cannot be made. Not until the mid 1930's did amoslte asbestos gain a market In North America when It began to replace crocidollte for high temperature insulation. Crocldollte was milled In Bound Brook, New Jersey In 1920 and In 1924 the operation moved to larger facilities In Millington, New Jersey. The many advertisements In the trade journal Asbestos from 1920 to 1945 Indicate that crocldolite was used In many products and particularly for Insulation of steam boilers, locomotives, and pipes. As an example, a product contain ing crocldollte asbestos and called "851 magnesian Sectional Pipe Covering" was advertised monthly in Asbestos from 1920 to 1945 (see also, McCullagh, 1980). Amoslte, crocldollte, and chrysotlle were almost universally used aboard ship during World War II; amoslte for high temperature boilers and pipes, crocldollte for packings exposed to acids cr salt water, and chryso tlle for low temperature and electric Insulation. The use of asbestos In Europe paralleled that In North America, with one notable exception - the extensive use of crocldollte asbestos as a sprayed-on coating to fireproof shipsjJ railroad cars, buildings, etc. Sprayed-on coatings were also used In the United States afttr World War II but the coatings contained, with few exceptions, chrysotlle rather than crocldollte. Sprayed-on asbestos coatings were not used on U.S. ships; the principal use being to fireproof steel building girders and as acoustical coatings in schools and offices. Asbestos trades workers. A very significant Increased nddence relative to the general male population, of lung cancer, as*estos1s and mesothelioma Is found In men who were employed In the "asbestos trades" Insulation of steam locomotives, boilers, ships, buildings; fabrication and Installation of asbestos-containing textiles, roofing mater als, cement products, tiles, wall boards, brake linings, clutch facings, filters, packings, gaskets, etc. Those In the "trades" generally us d several types of asbestos minerals during their working careers; most com only these were chrysotlle, crocldollte and amoslte, rarely anthophylllte. Significant exposures by any group if workers, at least for the past 40 years, to tramollte or actlnollte asbestos dusts has probably not occ> rred. UMesothelioma Is prevalent In the shipyard workers of Europe; at Wllcheren, Wllhelmshaven, Plymouth. Trieste, Hamburg, Nantes, Rotterdan, Malmfl (McDonald and McDonald, 1977). The extensive use of crocldollte aboard European ships prior to and during World war II Is suggests1 to be an Important factor In the etiology of this disease. 7A WIW2 Table 2a. Minimum estimates of Imports of crude crocidolite asbestos from South Africa Into the United States (1907-1020),* (1040-1945)**, (1946-1974).*** Year(s) Crocidolite crude (short tons 1007-1908 1909-1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 probably none no data little 9 1 no data probably none 1184 2081 837 1056 2979 704 1684 7040 1457 606 4873 5587 ? 0052 Total (1907-1929) 35,050 short tons 1040 1941 1942 1943 1044 1945 2708 2976 4213 4808 2046 3100 Total (1940-1045) 20,751 short tons 1946-1974 346.796 short tons *Some of the Imports were shipped through England. Small amounts of cirysotlle may be Included In Import figures but no amoslte. Figures do not Incltde any manufactured asbestos products. Most crocidolite came from the South (ape Prov., some may have come from the Transvaal. Source: Mineral Resources of the United States (1907)...(1929) U.S. Geological Survey, Washington, b.t. Crocidolite composed 19.4t of the South African crude asbestos Imports Into the U.S. during this period - which totaled 107,039 short tons, over 80,000 tons was amoslte asbestos. Sources: Minerals Yearbook (1940)...(1945), U.S. Bureau of Mines, Washington, O.C. Miners) Trade hotes7~toof^ent1a1 Series, No. 1-31, U.S. Bureau of Mines, U.S. Dept. Interior, Washington, O.C. (1940-1945). Minerals Yearbook (1946)....(1974) U.S. Bureau of Mines, Washington, O.C. 7B 06if993 Table 2b. Imports of all crude asbestos from South Africa (1930-1939)* Year(s) 1930 1931 1932-33 1934 1935 1936 1937 1938 1939 Asbestos Crude (short tons) 3615 2290 1370 4269 2529 7 3025 4248 6422 Total 27,788 Import statistics do not differentiate between various form? of asbestos. Little chrysotlle was Imported from South Africa thus the figures are for mostly amoslte plus crocldollte. Import data for crocldollte during World War II suggests that at least 20% of the 1930*39 Imports were crocldollte. The amoslte market was just developing In the U.S. In the 1930's. Most of the crocldollte was from the Cape Province. Assuming a ratio of 4:1 of amos1:e: crocldollte based on IWII Import figures, at least 5538 short tons of crocldollte was Imported Into the U.S. from 1930 to 1939. Sources: Mineral Resources of the United States (1930)(1931 . U.S. Geological Survey. Was iTnglon. B.c. Minerals Yearbook ( 932)... (1939). U.S. Bureau of Min*s, Washington, n.t. 04**994 7C Statistical data for 21 mortality studies of defined cohorts of asbestos trades workers (mostly male) are presented In Tables 3a and 3b. Of those that are continuing prospective studies, the most recent update Is given. Twelve of the studies are of asbestos factory workers, eight are of asbestos Insulation workers, and one Is of asbestos construction workers. In all, SO,143 individuals were followed (1 ,517 were female); of the 7,166 listed deaths 1 ,198 (16.7 percent) were reported as due to lung cancer and 402 (5.61 percent) were reported as due to mesothelioma. In the 21 studies, the lung cancer mortality accounted for 6.1 to 26.6 percent of all deaths; mesothelioma mortality accounted for 0 to 16.1 percent of all deaths (Tables 3a, 3b, Fig, 1). The workers Involved In study No. VI worked only with chrysotlle, those Involved In Studies X and XXI worked mostly with crocldollte, and those In the remaining studies probably worked with more than one form of asbestos. Estimates of expected cancer mortality are very difficult to predict, for cancer rates are modified by the individual's "lifestyle" as well as by occupation. The "lifestyle" contribution to lung cancer Is cigarette use. To better assess the significance of these health studies It Is necessary to examine the cancer-mortality patterns of cigarette smokers who were not exposed to asbestos dusts. Unless prevalence of smoking within the study group Is carefully evaluated It Is Impossible to predict accurately the healtn effects of occupational exposure to carcinogens such as asbestos, radon gas, and arsenic. Unfortunately, In few of the studies listed in Tables 3a and 3b have adequate assessments been made of the proportion of workers who smoke cigarettes. The contribution of cigarette smoking to the Increased incidence of disease has been evaluated In several studies and has lead to a consensus that this habit produces a very significant Increase In risk of dying of lung cancer as well as of the various cardiovascular diseases. The largest study of cigarette smokers is that of E. Cuyler Hammond and colleagues under the auspices of the American Cancer Society. This study Is based on questionnaires and mortality fo11ow-u> accomplished In the United States between July 1960 and June 1971 for approximately SI ,000 men (Hammond et al., 1978). The proportional mortality of lung cancer (percent lung cancer deaths relative to deaths by a'1 causes), based on the Hammond study, Is shown graphically In Figure 2. For a group of men who all smoke cigarettes (cohort of 100 percent smoers), lung cancer mortality Is approximately 7 percent at age 45, re ches a maximum of approximately 1(1 percent at age 70, then decreases si I1 htly at older ages. For a cohort of male non-smokers, lung cancer mortal1*y Is 2 percent at age 45 and then decreases continuously to approximate y 1 percent at age 95. Smoking is most prevalent In blue-collar occupations relative to pro fessional and managerial occupations (Sterling and Welnkam, 1978). This prevalence also holds true for the asbestos trades, mining, and milling occupations. In a group of 13,722 asbestos Insulation workers, whose smoking habits were recorded, 70 percent had a history of cigarette smoking (Selikoff and Hammond, 1975; Saraccl, 1977). In a group of 1 ,015 chrysotlle asbestos miners and millers 85 percem were smokers (McDonald et al., 1974). Data given In Figure 2 predicts that 'he lung cancer mortality for a cohort !A 0619993 93"> I l! h If 3 *m 2a I :3 -) j- * t ? In a tmj: : .. = 1 j ii 1 . Sfw s : ` ! il* 2 2 1 5 Is: ! 2 * :3 i i IIS S -1*2* x a* . 2i t 5 IS ?c?" i 1 * S *f i! * i ! 1 X s A i J TS ;t 3 3 | 2 3i: X h = # J? i i ;5 ? 3 3 J 2 a 3 f : * X =a 3_ :2 Xa* a 2-- i! 2 3-x2? za84 -x r2 8 l! i m a> M a a* X * m as 3 s , 1 : l!j! i 2 i i i ll ill! 1 31c i ij j jj j i. ijs! . > i i i i i X iu ? Ssr [ s 111 f1Si 1 1 1* ? ; si ii i 1 ! 1 == ii i h ii I --* 8 lit.-: hi!! hslii! l! i s j 5 ? E: .X : 33-S tJ -fi ! I3 - * 7s 2 a* ki !y > X * i lii! L1 :i hi li 8a S-._ s |9 1 1 1 m X * - ]i] Still 2i !1 :l j * 2 1 2- ! 1 2 ill Vi * * ii k \`V f 2 hi 1 2 2 s 3 SM X ...iiimifi i!.2 1 i : iS: i i i :I 2 i ii i 5-- 1 1" lE ll 2 < x3 : * 3m i: * i l-m s 4 3 i : 2 " 3 3% .1, Is % hi 5A i * 2 !. *K 5 ' x * In ll. j a s 3 Xa ! sL fil: J -1* - 2 3 2 * i| , 13 J 0 * i S> * il iii |,. it i I * 11 1 1 i i It ! I ! *!lll ! 5 S 32 ! 2 2 ^8 !;* is ; 3 s if j ! If} !1 f t m !H :| 1=1 ill1 li 7=. 2 Ki 2 2 < : it! 22! ?! i: ill iil III 111 ?l i 2 2 ! til 22: 12: i! 2 I i till1 1 | . = L:L?LiiiLt jI wjSi*vi lit. ISIS jlif 73 hi IIII** i???i !c 211 am ii . li 1! i i! ilif HI 1 i i j 11 I | 86 0619996 0617777 8C -> MESOTHELIOMA MORTALITY Figure^. Percent of lung cancer tie. ths In males relative to deaths 'y all causes {proportional mortality - lung cancer) plotted with respect to age for four groups (cohorts) having different cigarette- smoking characteristics and for a cohort of non-smokers. For example, for a cohort of 70-year old males which Is composed of 75 percent cigarette smokers, 7.8 percent of all deaths at age 70 are predicted to he from lung cancer. Graphical presentation based on data from Hammond et al. (1978). 8E 0*19999 composed of 75 percent smokers would be at least 6 to 7.5 percent, regardless of occupation. In Tables 3a and 3b we see that the lung cancer mortality for the total of 21 cohorts of asbestos "trades" workers was 15.7 percent approximately three times that expected If mortality predictions were based only on the apparent smoking habits. The risk of lung cancer due to asbestos exposure Is lower In non-smokers than In smokers (Saraccl, 1 <*77, J. C. McOonald, 1080b). There appears to be no relationship between smoking habits and the Incidence of mesothelioma, the disease is equally prevalent in smokers and non-smokers alike. Of the studies listed In Tables 3a and 3b, only Study No. VI of chrysotlle factory workers shows a lung cancer mortality that would be expected from the smoking habits alone. Asbestos miners and millers. Men working In the mining and mllHig of asbestos ore are generally exposed to only one form of fiber. A few exceptions occur In the nlning regions of South Africa where some workers have been employed In crocldollte, amoslte, and chrysotlle mines. Anthophylllte and tremollte asbestos miners may have been exposed to some :hrysot11e asbestos, for these minerals can coexist In metamorphosed uliramaflc rocks, for example, those of Paakklla, Finland. Epidemiological studies of asbestos miners and millers vho were exposed to only one form of asbestos are useful to understand how the different asbestos minerals affect human health. Table 4 gives the mortality data for the five major epldmslologlcal studies of asbestos nlners and millers. In addition three studies are given of miners exposed to cummlngtonlte and grunerlte amphi bole dusts and one study of tunnel worker; exposed to hornblende amphlfoole dust. Some classify these amphlboles *s asbestos even though they do not possess the physical properties requisite to be valuable commercially. Such a classification has been made In the ca;e of taconite mining by the courts (United States District Court for N1nni;ota, 380 F. Supp. 11) and by the U.S. Environmental Protection Agency (Reserve Mining vs. EPA, U.S. Court of Appeals Eighth Circuit, March 14, 1975); the latter has sued to prevent the Reserve Mining Company from dumping taconite tailings Into Lake Superior because of the perception that these tailings contain "amoslte asbestos" and thus constitute a threat to public health. For a complete review of the case see 514 Federal Reporter, 2d Series, 492-5*?, 1975; 256 North Western Reporter, 2nd Series, 808-852, 1977. Of Interest regarding this suit ere the health studies of the Reserve iron ore miners exposed to cummlngtonlte and grunerlte In the taconite rock (Table 4, Study B) and on the Homestake gold miners exposed to cummlngtonlte in 9A * ft If fa fi 1 5:` ** e e* tfa "c fa IS 1W * t; 9*7 cs SV . i; IfS *e c e $- i fa fa (Si 1 1r .i | O fa | w B fa C 1 ft) B fa S ft ft & 0-*h C9 fwt Bfa fa . :. B f fa fa fa A ft wB *w *fa s .8 fa * B fa C Q A fSafBa ft i: si 9> -- 9 s~.-.-: 9fa * _* ~o O A ft "*A# V *2 B A* ft BB |J Ow r -i O fa J| ft I ft i B fa . za *O fa fa A ift fa B 5 IS fa B JM * -uBB ft * f= 9 Nftl e or v ft rs #fal e 2: S ?2 s: sI 5s :s ; |" "o* * e 8* B 5s ss is f; fa s * *3 jl j ,! Ii. =1 . 8 1 w JJ fa fa i: 9* * i n X 9 #* & *Se' * ef =s'-' fa m "* A io S * fa e fa fa B ft fJ. i ii ii| |j fa fa fa 1 22 99 B -- fa B t X f Z& ft r l ]i BB * I! l| fa Afa9 -9 A a ** B 9 -- 5 a fa fa f9a 9 fa fa -- Aii> 4S- fa A 9t fa* s IB '. i; * A *ffaa 1IB: fa r1|. 2 lift fti !li fa ftr fa i* 1: ; 8 2; 182 *A fa fa S fa 5 2*8 fa -fa fa 2fa ft ft ? 2 fa fa s = B fa fa r SJ fa b : sx if * IS D 37 * -- s ft fa M 9 eA*Jf *. e * ec o fa* fa . ii U : 5 -* *. i: fl. ; 9 w .XX fa A 9 w fa fa 9 fa B C fa h iB ufa II ft fa IB !h 5r S -1 w = fa fa ~ 1 ii -ft *b 2 - !1 SI N1 BI 9 m. ** fa s~*. % fa .:s 8-. *B *< r. S |: <; w fa i b1 = Jl ` - i :: it > -I h -5 s Z 9w ^ B fa 9 W ffaa >. ft2 J-2 * r":| .25 5 os fa w A MW ffaa "2 2. il ft. -- x- ftl l! Si B si 2s: c-.-r2. IB *fa fa S). ; fIaS - s. 8 2 xs B f5a BiWhfa x ; : 7S1 u.`?j :: m fa AB fa ft f fa ft b ft ft fa fa B fa fa fa w9 it .t Is -! xil i ii " ii 's s *3 fa fa fa 9 b ** c 9f 22 3ti > B B fa fa I ft 9 fa B 9 9 fa 9 C ft B fa s' sE s. f*Aa ffaa ffaa aft- 9 a B fa ft u B eftfaa w fa mla 1 82 ' .9A ft fa" 2s1i ?8 X! (h8 r. fa fa fa fa fSftft >ft ft B ft 8 1= 15 H ii 2ft 'i 11. B 9 3 fa ft k. fa *9 * H si fa fa 2? .i X ll it ni X 11 X fa i 5 ii A 9 .1 Mffaa 1 Hi 99f-a i; tft fa * ft f*5 fa i fa ft? * A . 2 !i 8a A t fa i Xsi* Ww 8J| = A fa fa* Afa s* fa fa 8 fa a fa - 0It.2 nu I J 3 v* 2 Hit** e o9 n9 ii V e fa i fa i fa ft<fa fa fa fa : 8 ;u sis a * !s S1 tX i2 } * ft 1 fa l fa 9 fa fa - B 9B ? W rr VhA - ! {: fa fa fa 9 fa ir ^fa 9 A9 fBa *< B9 Bfa 9 fa fBa B fa ft W fa 8 fa 9 fa - fa -- fa s *i s^ .ii" !: i:;n r? ;s;s: SixtfaStfa U"*4 fa fa A -- ftftft-WI 9B , M2MI Table 5. Mortality Data (Jones et al., 1980a) for a Cohort of 951 Women* (578 traced) who assembled Asbestos-Bearing Filter Pads in tngnsn Factories (1939-1944). 2 Cause of Death Ai i causes Observed --rar- X Mortality --W Asbestos Exposure Crocidonte and chrysotlle G.I. cancer 10 6.0 Other cancer 35 21.1 Mesothel1 oma 16 10.2 Crocldolite only Mesothelioma 1 Crocldo'lte and chrysotlle Lung cancer 11 7.2 Crocldo Ite only Lung cancer 1 Crocldolite and chrysotlle *727 (134 dea3T were exposed to only crocidonte, 102 (10 dtad) to only chrysotlle, 99 (15 dead) to crocldolite plus chrysotlle, ard 23 (2 dead) unknown exposure. To make further comparisons It 1 . useful to examine the mortality with respect to lung cancer and mesothelloia In national populations. In Table 6 TabTSTT Cancer mortality in men ove z4 years or age for * nations (McDonald and McDonald. 197') Nation All Deaths (year) England-Wales Finland Italy U.S .A. Canada 278,617 (1970) 22,332 (1970) 272,795 (1970) 988,620 (.1969) 82,052 (1970) Lung cancer No.(l)* 24913 (8.9) 1586 (7.1) 11867 (4.7) 50481 (5.1 ) 4312 (5.3) Mesothelioma No.(X)* 15 i (0.06) < (0.04) no. reported 250 (0.03) 26 (0.03) Totals---------------------rtfZMIS------------------ tom V5.7)--------- I77T03T percent of all deaths (proportional mortality) are given the lung cancer and mesothe lama mortality of all males over 24 years of age In five nations. These ata are plotted in Fliure 1. We find that the average lung cancer mor allty of these five national popula tions Is 5.7 percent, a figure 1dent1<al to the 5.7 percent average mortal ity of the miners and tunnel workers Table 4, excluding cncldollte miners). The mesothelioma mortality of the flv . national populations is 0.03 percent (Table 6) and is probably significantly underreported because of: (1) the great difficulty In diagnosing this disease, even after autopsy (McDonald and McDonald, 1977, 1980; Vejlsted anl Hansen, 1980; Kannerteln and Churg, 1980; Legha and Muggia, 1977) and (2) complications arising In properly and consistently coding chls disease for ater information retrieval. It may be more meaningful to compare mesothelioma mortality among asbestos workers and miners, In whom this disease is anticipated, with the mortality In population where the determinations of the causes of death are based on a large number of autopsies and where abestos exposure Is minimal. A review 1 0*2M0 the gold-bearing schists (Table 4, Study 0, 1)1/. Studies B and E show no evidence'of asbestos-related diseases appearing In the study groups. Mortality comparisons, trades vs. mines. The cancer mortality pattern ror those in the asoestos traces and mining occupations Is graphically presented In Figure 1 where percent lung cancer mortality Is plotted with respect to percent mortality due to mesothelioma. The studies of the <$bestos trades workers (Tables 3a, 3b; Fig. 1 , open stars) show a very slgnlfUant excess of mortality due to mesothelioma relative to that found In the miners (Table 4, Fig. 1, solid squares) - with one exception, the crocldollte miners of Western Australia (Study F). In regard to high mesothelioma mortality, It 1$ Important to note two health studies of specialized factory workers who, during World War II, were employed at the task of manufacturing asbestos-bearing filter pads and of placing them Into gas mask canisters. One study (McOonald and McDonald, 1978) was of Canadian workers who, at three factories, were Involved with the manufacture or handling of crocldollte-bearlng filter pads. The maximum duration of exposure during the period 1939-1941 was no more than two and a half years. The cohort studied was composed of 93 men and 83 women (Study X, Table 3a). Of t>>e 56 now dead, 8 died of 1 ing cancer (14.31) and 9 of mesothelioma (16.11 . The second study (Jones et al., 1976, 980a) was of a cohort of 9 >1 women who worked either at a factory In Not Ingham, England or at a fa.tory In Birmingham, England. The Nottingham groip worked for only five mon-.hs In the years 1939-1940 assembling "civilian filter pads" that contained chrysotlle asbestos. The Birmingham group vorked for up to four and half years during the period 1940-1944 assembling "military filter pads" that contained crocldollte asbestos. The croclddlte was thought to have come from Wlttenoom, Western Australia. The mortality data is given In Table 5. None of those exposed only to chrsotlle died of lung cancer or mesothelioma whereas there were 11 lung center deaths and 16 mesothell >ma deaths among those who worked only with crotldollte. None of the womei In either factory, as far as Is known, was exposed to asbestos occupationally apart from their wartime work. Dust levels, as with the Canadian gas task workers, was considered to be very light to moderate. 1/Study E (McDonald et al., 1978) discredits Study D ((1111am et al., 1 >76). Study D was made on a sub-cohort of the Study E cohort. The latter study Is much more complete; satlstlcally It Is based on 631 deaths whreas Study D Is based on 71 deaths. In addition. Study 0 presents an Implausible mortality pattern: (1) No deaths due to silicosis, tuberculosis, or slllcotuberculosls were reported despite the fact that the mining company has been coping with a quartz dust problem for a century and (2) a 14*1 percent respiratory cancer mortality (Incorrectly Included as respiratory cancer were a sinus and a mediastinal carcinoma) was attributed to "cummlngtonlte asbestos" yet no mortality due to asbestosls was reported. The cummlngtonlte found In the quartz-cummlngtonlte schist host rock Is not asbestos; but rather, garden-variety rock.forming amphlbole. 10 uaeeoa has bean made by ROttner (1978) of the deaths in the Zflrich area of Switzerland where there are no asbestos mines, mills, or industries and where the cause of death Is often determined by autopsy. Among the 28,110 male deaths (all autopsled) from 1961 to 1976, 51 deaths were due to meso. thelloma (0.18 percent) and 2466 were due to lung cancer (8.8 percent). Among women (22,583 deaths) 23 were ciused by mesothelioma (0.10 percent) and 368 caused by lung cancer (1.6 percent). The proportional mesothelioma mortality for hard-rock miners, tunnel workers, and asbestos miners (other than crocldollte) Is 0.17 to 0.20 percent (Table 4). The asbestos traces workers, by contrast, have an average mesothelioma mortality of 5.6 percent (Table 3). Among the asbestos miners and millers there Is no question that those exposad to heavy concentrations of chrysotlle and anihophylllte dust over long periods of time have suffered a significant excess mortality due to lung cancer and asbestosls - but not to mesothelioma (Studies A, H, Table 4). The most detailed health study of asbestos miners to date Is that of the chrysotlle asbestos miners of Quebec (Table 4, Study J). Here, McDonald et al. (1980) have carefully documented the relationship between lung cancer Incidence and cumulative lust exposure. The'average dust concentrations that the miners and millers experienced during the working day were divided Into four categories depending on the work tasks performed during their careers In the mines. These are: low level 2.5 to 4.2 mpcf3/, medium level 4.3 to 9.4, high level 11.4 to 23.6, and very high level 46.8 to 82.6 mpcf. The mean within tiese four categories In terms of chrysotlle fibers per cm3 i$: low 10 ''Ibers/cm^. medium 21 fibers/cm3, high 95 fibers/cm3, and very high 194 fibers/cm*. For the men exposed for over 20 years (see Table 17, col urn A) in the low and medium dust categories (averaging 6.6 mpcf or app'oxlmately 20 flbers/cm3) total mortality was less than expected (SMR 0.94). For these m**n there was a slight risk of excess lung cancer (SMt 1.15) ard resplratiry tuberculosis (SMR - 1.14). As exposures of 20 flbirs/cm3 are an order or magnitude higher than that experienced now (dust levels for the past ew years have been maintained at less than 2 fibers/cm3), miners working i lifetime under the present dust levels are not expected to present a>y significant health problems relative to those In >ther mining Industrie (Liddell, 1981). McDonald et al. (1980) have also studied the health stittsties of a cohort of 440 women who also worked In the Quebec chrysotll ? asbestos mines and mills. Of the 84 who have died there was one death due to lung cancer and one due to mesothelioma. 2/mpcf millions of particles of roc-: dust per cubic foot. Conversions of this figure Into asbestos fibers per .ublc centimeter, the isual measure ment for Industrial hygiene monltorlni, Is difficult but an approximate and conservatively small figure Is: 1 mpcf 3 fibers/cm3 (McD maid et al., 1980, p. 21 , 23; see also McDonald and Becklake 1976). 12 0420004 Crocldollte exposure. There are persuasive data, many already surveyed, which show tnat crocidollte asbestos Is much more hazardous than chrysotlle, anthophylllte, and amoslte. Of the mining populations of the world, only those In the crocldollte mining areas of the Cape Province of South Africa and at Wlttenoon Gorge, Western Australia have a statistically significant Increase In mortality due to mesothelioma. Also, mesothelioma deaths have been reported among the residents of these areas who are not employed In the mines or mills. For example, Webster (1978) reports that the South African Asbestos Tumour Reference Panel placed 712 cases of mesothelioma on the register, which Included all the known cases since 1966. Of these occupational and envlronmental background was established for 420 case;. Actual mining exposure accounted for 139 of the 420 cases of which 120 were In connection with Cape crocldollte mining and two with Transvaal crocidollte mining. There were only four mesothelioma cases In those associated with amoslte mining and two of these had been exposed to Cape crocidollte as well. In the chrysotlle mining Industry there was only one case - a miner from Rhodesia. Of the ion environmental cases (those not employed In any occupation where asbestos Is used) 93 had been exposed to Cape crocldollte, two to Transvaal crocldollte, and one possibly to amoslte. Additional prevalence studies In the Cape Province (Talent et al., 1980) discovered 65 active cases of mesothelioma In people who had presented themselves for medical examination. Fifteen of these cases appeared In two groups, numbering 755 and 947 Individuals, who were once employed In the crocidolite mines. An additional thirty eight mesothelioma cases appeared In a survey of certain patients at the St. Michael's Hospital In Kurumin, Cape Province, who were not responding to treatment for suspected pulironary tuberculosis. Fourteen of these mesothelioma patients were known to have worked In the crocldollte asbestos mines, lastly, 12 of the 65 cases appeared In a medical survey of 53 females who. In the pat, hand-cobbed crocldollte asbestos. In contrast to the prevalence of mesothelioma in the Cape Province, this disease Is very rare In the Transvaal where all of the world's amoslte Is mined. Wagner et al. (1960), In regard to their Initial discovery of the association of crocidollte asbestos with mesothelioma, state (p.2fi<l) "the tumour (referring to mesothelioma) is rarely encountered elsewhere In South Africa. Qurlng the past five years, with the exception of the present series (In Cape Province), no neoplasm of this nature has been diagnosed amongst 10,000 lungs examined at the Pneumoconiosis Bureau In Johannesburg, or In the Pathology Department of the South African Institute for Medical Research." The Incidence of mesothelioma In Zimbabwe (Rhodesia), a country which is a major producer of chrysotlle but mines no other form of asbestos, is very low. In a communication to Mostert and Melntjes (1979), the Secretary of the Rhodesia Pneumoconiosis Board stated that no cases of mesothelioma were reported In the mining Industry. It Is of Interest to note that two cases of mesothelioma were reported 1 i the Rhodesian railway industry, a locomotive engineer and a storeman, fhe locomotives were insulated with crocldollte asbestos to which these t<o men were exposed (Mostert and Melntjes, 1979). Cochrane and Webster (1978) report 12 cases of mesothelioma In men employed as Insulators In the locomotive workshops of the South African Railways. 13 0tt2QOO3