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r !j ; KZf The Work Environment of Insulating Workers J. LeROY BALZER snd W. CLARK COOPER, M.D. Zhvuion of Ensironmdila/ Health Sciences, School of Public Health, Uniuernty of California, Berkeley, California 94726 With the cooperation of the asbestos worker*' union and insulating contractor*, a study is being made of the environmental exposures and the healtB of insulating workers in the western United Suits. Surveys have been made in a number of work situations, including small commercial building, major industrial construction and marine operations. Major emphasis has been on exposures to asbestos-containing materials, fiber glass, cork, plastics, and adhesives. Trends in product usage are presented, as wed as illustrative dust counts, based on membrane Eller and impingcr samples, for various components of the insulator's job, e.g., prefabrication, applica tion, finishing, mixing and tearing out of old insulation. 'A . r, .7. : Introduction YV7 ORKERS IN THE insulating trade make up an occupational group known to have exposures to asbestos that are varied and difficult to control. In recent years, in vestigators have shown that the relationship between asbestos minerals and human disease extends beyond a disabling pneumoconiosis produced in some workers. Evidence has ac cumulated that asbestos workers have a high er incidence than average of malignancies of the lungs, pleura, and peritoneum. Asbestosis in insulating workers has been reported in England by Ellman1 in 1934 and by Leathart and Sanderson5 in 1963; in the United States by Fleischer et a!.3 in 1946, Pendergrass4 in 1958, Marr5 in 1958, and by Seiiko/T e: al.* in 1964; in Sweden by Ahlmark it al.3 in 1960; and in Finland by Ahlman* in 1966. Selikoff* reported lung cancer deaths in insulating workers in New YorkNew Jersey to be over six times expected; TKji involution wu tupoonetf by R*irch Gnnt OH00204. from tfte Pobic H*uih 5r>ce. U. 5. Department of Health. Eduction ana VVtlf*r and received preinninarv ruopen from Genenj R<turcn Supiwrt Gram 1-SOl-FRCi44l Puolic Health S*rvce, L. S Department of Health, Education ana Welfare Thu report wai presented ai the American Industrial Hv|iene *'locution Conference m Chicago. Illinois, on May 5. 1567 Dunn and Weir3 in 1965 reported a higher 4; than expected incidence of lung cancer in q, California; and Keane and Zavon10 in 1966 1$ in their descriptive report of the insulating trade in Cincinnati also described an excess of lung cancer. N Because asbestos may be a widespread en- * vironmental contaminant and the established threshold limit may need re-examination, there is need for a thorough appraisal of the work environment of the insulating worker. We are now in the process of doing a study of San Francisco area insulating workers in order to determine the incidence of pneumoconiosis and malignancies and make observations and measurements on the work environment. This report summarizes our preliminary environ mental findings on the materials used, meth ods of application, and dust and fiber con centrations. Background Information on Union Membership This study was made possible by the whole hearted cooperation of the International .As sociation of Heat and Frost Insulators and Asbestos Workers (both from their national headquarters and from the officers of their various locals), and by insulating contractors., individually and through the Western Asso- 1 222 Ii t t t c ii CO --- 1 CD CD CD CD? CO r\) 396440 ter in 56 ng :ejs en- . -.ed . on, the -.er. oi - *tsis jr.c This ;on- -ship _ sleAs;rd ,e:i ors. ssc- y c;a[ion of Insulating Contractors. There are ' i aoprostmaiciv 1,800 insulating workers in the V\; Western States, but this report is limited to " workers within the jurisdiction of the San *. Francisco Local (No. 161 which encompasses j. Northern California and Northern Nevada. 'i - This local at present has approximately 500 i. members, '09c of whom have been in the trade more than 10 years and 42 9c for more than 20 years. The union's health and welr (are fund has sponsored a program of volun; tary chest films for the past 10 years, and 80% of those eligible have participated. Re view of these films has shown that about 25% of the members have roemgenographic chanees stroncly supporting a diagnosis of asbestosis with an equal percentage having sug gestive changes.11 Most of the local union members work for one of the 20 or so insulating contractors in ,. the area and travel from job to job with a soecinc firm. There is considerable shifting > from contractor--to contractor so that manv - men have worked for all of the major conW tractors at some time during the past 20 or 25 years. Nevertheless, the trade is a stable one, arising out of a high wage rate and a rigid apprentice testing and training program. . Men who qualify and pass through the ap! . prentice school program tend to stay in the trade for their working life. Insulating workers learn to do all the - niior jobs in their trade and usuaiiv will work a: anv job assigned by their union dis patcher. Some prefer to work in heavy con, siruction or on the waterfront. The maior foes of work in which men are engaged can be classified as: (1) commercial building, which invoives the insulation of pipe and duct svstems in office buildings, apartments, thopomg centers, etc.; (21 heavy industrial building, which involves the insulation of turbines, boiiers, pipes, duct systems, and processing equipment in power plants, fac tories, etc.: and (3' marine construction and recair. which invoives insulating turbines, sfers. pioes. and duct Ssstems m ships in &ot.n navai and private vessels. Local 16 i does not have jurisdiction in U. S Navy shie lds in. the Bav Area, which have their own I iccal unions, but manv of the memoers have in the past been empioved in the navai ship yards The following is a breakdown of employ ment by types of construction of the 401 ac tive members working as of March 31, 196': 100 of the workers were employed in com mercial building; 236 of the workers were employed in heavy industrial building; and 65 of the workers were employed in marine construction and repair. The majority are employed in the building trades. When there is an increased demand for ship construction and repair, there must be a shift of the union population. For example, during World War II, more than 1,800 insulating workers were employed in Bay Area shipyards, even though the local's membership was only 500 mem bers. This was due to "travelers" from other locals and a large number of workers from other trades given temporary permits to do insulating work during this peak period. How-ever, the general picture is that there are few travelers, and the Local 16 membership handles most of the jobs in this area. Rota tion between employers tends to keep the local member working in this area for the duration of his working lifetime. Insulating Materials Used Our analysis of the insulating worker's en vironment indicates that they are predomi nantly working with calcium silicate and magnesium carbonate insulating material con taining asbestos fibers, fibrous glass mate rials, plastics, foam glass, cork, and adhesives i 1. Materials Containing Asbestos-- 100cc Amosite blankets 959c Amosite--5% filler 10-15Cc Mixed amosite and chrvsotile --859c magnesia 10-15cc Amosite--859c calcium sili cates 10-159c Mixed amosite and chrysotiie --859c calcium silicates 10-159c Mixed amosite and chrvsotile 859c calcined diatomaceous si lica !CQrr Chrvsotile asbestos shorts for finishing (mud) ''0rr Asbestos shorts and 509"c ce ment for finishins (mud) :i .1 .\A4 t1 .-I. i 5 it's I.vii :v3 iff Si in'1'; fM jy.ii 1 ''iiv! + kii.*i . i V:: ? '[ : " i! I i 396441 oo CD CD CD CO CO 4 ' ItJ' i, i ?.. 1 i ^ : : | :! ^ 1 i I May-June, 'OSP. 2 I W,\ _i : ..I i- C-OI! ;-l !i I N : - i .i >M >M 5 V, - -- MonnnmrK--rnmpreserc "'.a.'' and resin binder ]\oi Is Picfubiicatcs--pipe and i!uc: covenng Mineral woo! Hie'n temperature insulation Finishing materials (mucs) Mineral wool anc cement 3. Plastics-- Poi\ stvrenes--p re fabricated product, powdered Polyurethanes--foam in places, prelabricated products 4 Cork \QOcc cork blocks 5 Glass Flakes-- Foam glass Taulf. I Estimated Percentage of Volume and Application Time bv Types of Insulation Material in Use in the San Francisco Bav Area Tvpe of Insulation Material Vohitur of toiai Ton! Aabenot Fibrout Other icor* rubber, foam qlaji. poi-rnvrrnri. pot sure mane* i 100 45 5 iO Apphcauot 9b of utns. 100 55 40 5 TaDLI II Estimated Percentage of Current Use of Fibrous Glass ana Asbestos Cor.tainmc Materials bv Maior Types oi Construction Tvpe* of Comirucnon F broui i rjtt iauon Mater tan L ied Total F inroui GUu Athntot Corruncrcial buiihme mduttrial bojidmf Marine comirucuon and repair IUU 100 n^rc 30 70 3<VTr :n 80 Taalf HI Characteristic Properties oi Chrysolite ar.a Arv.osno Proneruc Cj^'iai uiMCturr C jlor Approximate diameter ot imailrti nocri t* . Specific eras nv I ndex of rf frar t tern Chrvsot ite Sltert siiic.ni- \\ hitr 0 nr$_n o:3 : i: ! >-%l I.*'' Amomr Cham niicatc Avn-Cre* 0 05-0 1 3 45 1 oj`M 'GO 11 A 1111 n v i \ r s Epow and solvent; asphalt base and solvent Wheat paste Silicones Magnesia Portland Cement Table I is an estimate of the products used by volume and the approximate times spent in applying them. This information was ob tained from the contractors, men in the trade, and from personal observation during the past year. This table shows that fibrous asbes tos and glass materials account for 90'yo of the materials applied. Table II presents the percentage of fibrous insulation materials used by the contractors in our area by major types of work area. These fibrous materials were of paramount interest to us in reconstructing the work-a-day en vironment of insulating workers. V :1 i Physical and Chemical Proper+ies of Fibrous Materials Asbestos Asbestos is a commercial term applied to a group of fibrous silicates. They include chrysotile and the amphibole minerals--crocidolite, amosite, anthophvllite, tremolite and actinolitc. Chrysotile (hydrous magnesium sili cates) is the most important commercial as bestos mineral, presently accounting for about 90Cc of the world's asbestos production. It occurs oniy in serpentine (hydrous magne sium silicate minerals'] rock formations. Amphiboie tspe asbestos is found in five cornmerciailv useful forms: crocidolite, amosite, anthophvllite, tremoiite and acnnolite. In the United States insulation industry, chrvsothe (Canadian,' and amosite (South African) are most often used in manufacturing insulation materials (Table III) A unique phvsical characteristic of asbestos is its ability to longitudmallv subdivide into fibriis of moiecuiar diameter. The fibriis arc too srr.ail to be counted with ordinary light microscopic techniques, making it cimcu.t to assess the true fiber exposure. From the literature and front manufactur ers and their representatives, we ascertained t t / S! U g c o a tc s: t; h. Yr :; i u (... cn cr cc 396442 STOOI3085 -53 ana .isea Dent ooaae, the ;bese of rous rs in hese erest e.n- ; to a chry- C1C0- d acn silia! asabout n. It asneAm- nrr.erlosite. In the .50iiie n'' a:e .'.alien besio.' e into .Is are heht - it to ...-cci _{'ner\ccn ir.dustr-.ci Il-.^icnr .-Uioaano'i /< mat J-iD the approximate amounts and types of asbcsZ. :os fiucrs which arc used locally in 11 diflViI ent asbestos insulating products, manufac| tured by seven major producers of insulating re materials in the United States. This infor- mauon is summarized in Table IV. We con: firmed the stated types of asbestos fibers in W seven of the materials by x-ray diffraction analysis using a Sorelco X-ray unit equipped *y with a copper target and x-ray diffraction y" tube. The manufacturers of asbestos insulating V materials use varving amounts and types of !. - asbestos fibers in their products and may re- brand their product for distribution by another manufacturer. Contractors will also order I"1 specific tvpes of asbestos insulation because of ' their thermal properties and not because of ' the tvpe of asbestos fibers they contain. These U practices on the part of manufacturers and 5. contractors make it impossible to reconstruct a vorking population that has had a ''pure" exposure to one type of asbestos fiber. It has - been our practice, in environmental sampling, 1 x- * to record ail tht insulating materials being used in order to determine product accepta; : bility bv the insulators and to determine if i- any one type of insulation material produces more free fibers. Fibrous Glass ' Fibrous glass consists of a mixture of silicon dioxide, oxides of aluminum, caicium magnes;um, boror. and other additives. In general, V the fibers of most commercial insulating prod\ ucts have a mean diameter of 4 microns or : greater. Although this paper will not directly . _ consider fibrous glass exposures, we have been obtaining environmental data and will anit later. In our laboratory, we have optically de termined the diameter in microns of various surnpies of fibrous giass insulating materials uscd in our area. The acoustical materials ha\e the largest diameter: 11 to 14 microns: lhe buiidmg and duct insulation: 4 to ` ttnerons: pipe coverincr: 4 to 6 microns; and 'he special high temperature material: 1 to ^ microns. f _ It is evident from this data that it is not I C;!t'c; ;o find giass fibers in the worker s ?r-A'ror.mer.t that are of a lespuabie si/ti. Huh the increased use of high temperature insulation and special fibrous glass insulation materials, we are likely to see more and more fibrous glass insulation materials with a mean diameter of respirable size. Environmental Data As was described in the previous section, the insulating worker works with and is ex posed to a myriad of materials and condi tions. Many times the materials he is exposed to result from the activities of other trades in the area. Obtaining a true time-weighted exposure under these conditions is impos sible. It would require hours of observation and sampling of each worker in order to even attempt to estimate the integrated dose. Exposures in most other industries are fairly constant by comparison, in that workers con tinue at the same job in generally the same area. However, the insulating worker is al ways in a changing environment; the work locations, his position, materials, humidity, temperature, ventilation, and any number of other things are in a continual state of flux. In an attempt to reduce this to some order, vve have classified all the jobs per formed by the insulation worker into six' major categories: (1) Prefabrication: ma terials are precut and shaped using hand or power saws either on the job or at the con tractor's shop (10% of his time). (2) Ap plication: materials are fitted, hammered, or carved, and attached to the surface by wiring, or gluing (40% of his time). (3) Finishing: materials are coated with asbestos containing cements, resins, asbestos or cotton cloth, or petroleum based sealers (30% of his time). (4) Tearing out: removal of old or un usable materials in the process of insulating or remsuiating (10% of his time). (51 Mix- Tabli IV Percentage and Type o( Asbestos in Insulating Products in Current Use Tp< of Vhcfto* 4niontt Ajrmwie VinoH.u--Chr>AOl>le CufA'Ol i V C-iU-WM.sc Percent Wcjfhi Nymijff n{ Product* lO-lS^c 10-15 10-15 a*-:on 7 3 > <Jl.wn --1- r-"r i*- r -1 396443  nr? l 126 Ma\-June, 19uo Tailf V Dusi Concentrations Based on Impinccr Samp.es by Job C'assi ncation T a n i t VI Kibcr Concentration Based ion Membrane U o Fi.ter Samptcs bv assincaiion Job lion M.Mn*' Cent ri Mean DlOPCl M fdun R*n|e Job C'auiftcaiion N umber oi Samp>es Mean r.iK-.A-rc Median Rancr 65 46 o &-:a 0 Prc S abt scat ion IT 35 :5 o.a-a: Aopncjnon q :a 24 i :-6 : Fumrunc a 5: 51 2 5-3 6 Tearing oul 6 9 1 8 4 : 8-16 0 Mi\mg 9 14 14 0 6-18 Central :: 8 3 8 4 0 1-24 3 45 6.4 1 4 0 j -3 1 6 31 0 8 o i-:< i: 8 9 4 9 0 :-26 3 22 2.6 1 4 0 2-Ki: 16 4 8 C 3 0 1-22 9 ing: mineral wool, asbestos, fibrous glass, and cements or glues are mixed separately or in combination in buckets or troughs (5% of his time). (6) General: cleaning up of old insulation, transporting of materials (59c of his time: The percentage figures indicating the amounts of time spent at each of the job classifications are, of course, variable and are only intended as rough guidelines. For the purpose of this paper, we will limit our discussion to the environmental data obtained during insulating operations when oniv asbestos containing materials were used. To compare our sampling data with the present threshold limit value (TLV) ot 5 million particles per cubic foot, we have taken a number of midget impinger samples aiong with our other methods of sampling The results of the impinger samples are summarized in Table V and are either breath ing zone or general air samples of a particular insulation operation. All the samples were counted in accordance with the standard procedures prescribed bv the American Con ference of Governmental Industrial Hygien ists and include both grains and fibers. It wiil be observed from Table V that we have three distinct areas--prefabrication, tearing out. and mixing--where the present TLV is exceeded. Because of our interest in the roie that fibers play in the pathogenesis of asbestosis, we placed the major emphasis of our en vironmental sampling on obtaining fiber con centrations under various working conditions. The personal and genera! samples were col lected cn Millioore T\ pc A A Filters rr.otir.te:: in field monitor cases Most o: the samp.es were breathing zone samn.ts worn iv me workers for periods ranging from 30 minutes to 3 hours. Since it was easy to overload the filter with fibers during heavy dust periods and negate the countability of the sample, it was necessary to replace the field monitor cases several times during the sampling period. The fibers were counted by clear ing a wedge-shaped segment of the filter using a modified technique of the Uni ted States Public Health Service11 and sized by the length and diameter at 430x magni fication using phase contrast illumination; we will only refer to the total fiber counts In this paper. A fiber is defined as having an aspect ratio of 3.1 length to diameter. If Timbreil's criteria13 for respirable fibers (diameter smaller than 3.5 microns) was used, 989c -- 29c of the fibers we have counted would fall into this category. The fiber counts per cubic centimeter are given in Table VI by job classification. Discussion Our environmental observation in the in sulation trade confirmed our initial impres sion that the varied job assignments, con struction methods, and materials used in current work practices make it extremeiv difficult to reconstruct a time-weighted aver age exposure for the maior hazardous dusts and chcmicais. Reconstruction of past ex posures is impossible. Although materials in use have changed over the past 20 or 30 vears. with an increas ing use of fibrous glass and a decreasing use of cork, the construction industry continues tc demand asbestos-containing insulation ma terials The ir.sui.mon worker's exposure ,c asbestos fibers is not disappearing It is a.sc evident that cr.nu.irx to most ocner l r.jtcti > t e GO CD CD CD CD CD cn 396444 1-i.tj;:-:-. n A;so;ia:;: 5-ates sr.custnes ".'.erf ascc<tos exposure* oc- c,,r. ci'.ivsoule asoestos has not vet supplanted '.iv of ,-imosiir nsn*-Mrts in liir m.miif.tr- tuf.ng of insulation materials. Amosue ex posures are the most significant in the in- iaiJf.r.c trade The breathine-zone dust levels found in die dustiest operations observed were not as h:ch as the incidence of pneumoconiosis r..a\ have iec us to expect. Some sample areas exceeded the present threshold limit value TLV'- recommenced by the ACGIH however, these samples were not for extended periods of time. Although we attempted to sample the dustiest operations, the timeweighted averages lor dust samples concainme asbestos would probably not exceed the TLY in most situations, even on ships. This conforms to findings by Fleischer et al.,3 by Marr: and bv Leat.nart and Sanderson1 and to iccer.t.v reported findings bv Ferris'* who last vear reported studies in the same snip\ards earlier appraised by Fleischer 3 The present TLV for asbestos was recom mended bv Dreesscn. c: ai" in 1938, after epidemiologic studies- in textile mills using chrysoiiie asbestos. It was not intended for extrapolation to all forms of asbcsios use under all circumstances of exposure The proven, occurrence of pneumoconiosis in in sulating workers exposed intermittently as rimer.neci in this paper and by the authors prev icuslv cited suggests that the TLY for asoestos is too high Our studies are, how ever not yet complete enough to v\ arrant a final conclusion. We cannot eliminate the possini.utv mat otner components c: t*c in sulating mauuims iua\ be synci gisuc. The mnrii-nrr nl nnrumnrnninsis in these vsnikers. the need for better environmental con trol measures, and medical surveillance will be the subjects of more detailed latci repot ts. References 1 Elljha*. P Pncuraocomotii Pam III Aabeauxii But ] Roam 7 281 (1934) Pulmonary 2 Li*tma*t C L., and J T San out son Some Obsena* non* on Asbcscoais. Am 0<<vp. Hyg 6- 6b (I9G3/. 3 Fuxiicxut, W E . F J Vilas. R J. Claoi. and P. DiiMitt A Health Surfer oi Pipe Cervenn* Operations in Corutrueunj Naval Vessels. J. !*dau. Hjg. <3 Tax. 28- 9 (19461. 4. PixocaoiASS. E. P.t Silicons and a Few of the Other Pneumoconioses. Amt* J. Ratmgtnai. Radium Thtrapy Sncl. lit*. 80: \ (3953). b. M^aa. W. T.: Asbestos Exposure Dunne Naval Vessel Cherhaul. Amtt. /ndtuf. Hyg A hoc. J *5. 264 (1964). 6. SeuRorr. 1. J., J. Chum. and E C Hauvono Asbes tos Exposure and Neoplasia. }-A M A 188 - 22 (1964). 7. Amlmaxk. Axu.. T. Baud, and A. Nvstio*: SHieotu and Other Pntumitaamtt m Su/tdtm op. 353-357. Scandinavian University Books, Stockholm, Sweden (1960) 8. Aiilman, K.: Aabeatosii Araonc Insulating Workers in Finland. P^oetelingt at the 14th l nterauiamai Congtttt an OteveationaJ Health pp. 237*240, Vienna. Austria (Sept. 19G6/. 9 Dunn. J .. and J. M. Wui: Cancer Experience of Several Occupational Grouot Followed Prospective! y Amtt. } Pm Lilt H tilth 55 1307 [1963). 10 KiANt. W' T.. and M. R Zavqk Occupational Haaarus o( Pipe Insulators. AMA A'ch. En.-ira* Health 13 171 (1966). 11 Conrt'a W C. , and I. R. TAnaxiiAH': Unpublished Material (i960) 12. Eow-ajlos. G. H , and J R. Lynch The Method Used bv the U S. Public Health Service for Enumeration o( Mbriios Dust on Membrane Filters. Unpubiisncd (1966). 13 Timmu-l. V.: The Inhalation of Fibrous Dusts. A*. V Y Acad. Set. 132: 255 (19631. U rcn*ul CommttMtf 4fi/ut (l^O. Dittsira', W. C-, J M. Dau> Vaixi. T. I. Euw*juv ] M. MiUJJt. and R. R. Sayus A Study at Aibtitatu m in# Atbtiiot Textile Indvilne Public Health Bulletin No 241. L. S Govt. Prinnnj Office, W'ashmcion. D C (I938i Received June 20. if- 8 r r r .Wi V* ,u> Errata Ir. the article "The Assessment of the Work Place--A Prerequisite to the Diaer.osis of Occupational Chest Disease" bv Kenneth M. Morse (A.l.H.A Journal 23 135-143. March-Aprii 1967', several errors unfortunately appeared or. page 139. In the text table in right-hand column, the time percentage for item "3 Misc. (timbering, bit change, etc.)" should have read 49c Immetiiateiv following this table the calculation for the time-weighted average concentration (TWaC) should have been: TWAC = ff38.5 X 4 68' - (6.5 X 1 64' - (4 3 X 0.32) -- (3.50 X 0 48' -(45x 0 987/8 = 197 9 8 = 24 7 mppcf tV $ Yj 396445