Document ymrVjEgD72YoKv9jkbKkN2Z0D

UNIVERSITY OF_CAUFORNIA, BERKELEY /y cj/ c*jtCLT e*'U ivinc U01 Afcu.ti * nicn*ior. an niLro <** n*r.ivr) lb ftte* SCHOOL or TUJUC HCALT1I CAliU W*|iiii;n MAI.!. UcT^ (Bb vci'kxlxy, CAuroriMtA ?2e -- tsueFC -- ^--W. * .* (_'I September 11, 1970 V \ I Lee B. Crane, M.D. Medical Director Pittsburgh Plate Glass Company One Catevay Center Pittsburgh, Pennsylvania 15222 Dear Dr. Crant: ' Enclosed are somewhat better copies of our report on the Unibestos project. These will give better reproductions than the copy sent to Mr. Price. 1 trust that these will reach you before your departure for Washington and that they will be use ful to you. Sincerely, DPF: js enc. Douglas P. Fowler Industrial Hygienist l i l1 !\ I r ( r < ; * ^ ( PROJECT TITLE: "Dust-Producing Potential of Construction Materials" INVESTIGATORS: Bernard D. Tebbens, Sc.D. Professor of Industrial Hygiene Engineering J. LeRoy Balrer Associate Specialist in Industrial Hygiene W. Clark Cooper, M.D. Professor of Occupational Health in Residence FROM: DATED: Irving R. Tabershaw, M.D. Professor of Occupational Medicine Division of Environoental Health Sciences School of Public Health University of California Berkeley, California 94720 September 9, 1970 < < 1 4 DUST-PRODUCING POTENTIAL OF CONSTRUCTION MATERIALS Bernard D. Tebbens, Sc.D., J. LeRoy Balzer W. Clark Cooper, M.D., and Irving R. Tabershav, M.D. Purpose of Study The purpose of this study was to develop methods for assessing the hazard potential of asbestos-containing construction aaterials. The methodology was to be developed during a systematic study of four commercial insulation products containing asbestos. The results include the actual concentrations of airborne asbestos fibers found to result from operations typical of the industrial uses of these products. The necessity frequently arises in industry to predict the potential hazard during comminution of a solid material. In other words, "is the dust produced by sawing, drilling or filing of a solid containing a hazardous component necessarily of the same composition as the parent material?" At first glance, the answer must seem, "Obviously, yes." In reality, however, there are several factors which can result in a different distribution of components. Occupational exposures to potentially hazardous dusts may be affected by the conditions of use of the materials from which the dusts are generated or by the physical characteristics of the material,^*^ Occupational exposureeof construction craftsmen to airborne asbestos fibers are primarily a result of the comminution of thermal insulation materials during their installation, repair, and removal.^ Inhalation of asbestos fibers has been shown to cause, or be associated with, an Increased r f r r ( f f I ( ( C ^v t -2- 45 Incidence of fibrotic and neoplastic disease. ' However, at present, there are no thermally suitable alternatives to asbestos-containing materials for the prevention of heat loss from high-temperature (750*F and higher) pipes and boilers. There are two major types of asbestos-containing thermal insulation products. One of these is made by binding a mat of amosite asbestos fibers with sodium silicate, either with or without the addition of diatooaceous earth (Product B). The minimum asbestos fiber content of this type is approximately 602. The other major type is prepared by baking a slurry of calcium silicate and amosite and/or chrysotlle asbestos fibers and contains approximately 10-152 asbestos (Products A, C and D). It has been suggested that exposure of insulation workers to asbestos fibers might be substantially reduced by restricting the use of products which have a high asbestos content. However, the two types of materials differ significantly in their physical properties so that the asbestos concentrations in aerosols generated during the handling of the two types might differ in ways not directly related to the concentrations of asbestos in the parent materials. The 602 asbestos/sodium silicate insulation has been described as being more readily cut and shaped than the calcium silicate products, requiring the application of less prolonged or intense force for a given shaping operation. There are also significant differences in the two types of asbestos fibers used In the materials, amosite being of greater specific gravity than chrysotlle (3.5 vs. 2.5), and having individual fibrils of -3- , larger diameter than chrysotile (0.1 Uta vs. 0.01 pa). Thus, It would seem that there are theoretical arguments favoring the product with higher asbestos content. The greater ease of fabrication ' would mean a shorter period of production of the aerosol, and the larger, more dense amoeite fibers would tend to fall out of the produced aerosol more rapidly than will chrysotile fibers. Research Performed Four thermal insulation products, 9-inch outside diameter and 3-inch inside diameter, containing differing asbestos types and concentrations were tested for respirable dust production tinder conditions simulating actual usage. These products were purchased "blind"; a .reliable third party not connected with the University or any of the manufacturers { concerned purchased the products through the normal turret channels ordinarily used by him In his purchases of other Insulation products. Thus, ve entered the market randomly; the products used in this study are ( a "grab sample" of the products which might be delivered to any user. Product D was the only one of those tested which did not meet the original broad specifications; it was supplied as two 1 1/2-inch layers and not the ( single layer of the other products. The wholesaler confirmed that Product D is not supplied in a single layer in 3-inch thickness. Therefore, it was used as received since this Is the way it would be supplied to Insulators 4 In actual practice. A test chamber (shown in Figures 1 and II) was constructed measuring 10*4" long by 9*8" high by 10* wide. The total volume was 1,000 cubic feet. t i The room was lined with 0.006" plastic sheeting to facilitate cleaning. Farr Company HP 200 filters were used to filter the supply air and the exhaust. Air exchange rate between test runs was 290 cubic feet per minute. After each run, and between products, the room was flushed for a period which varied depending on the observed "dustiness" of the room but was a minimum of 20 minutes (about 6 air changes). Before each change of product (or change in process), a background air sample was taken in the "room" position (described below); each sample subsequently taken in that series (or run) was then corrected by having the background concen trations subtracted. The following operations (described in greater detail below) were performed on each product by an Insulation mechanic (journeyman asbestos worker). _ I. Simulation of pipe covering, and tear-out of heat stressed pipe covering. II. Power sawing of the products to simulate on-site fabrication of specific shapes of the material by a bandsaw; and the "scoring" of blocks. III. Pounding with a simulated hammer to estimate the effects of force-fitting (not performed by the insulation mechanic). In each of these operations (except the tear-out and pounding), the insulation mechanic was permitted to set his own pace; the specific plan of operations was determined in consultation with him so that practices usual to the trade vere followed. The insulation rr>echanic used a "Vhitecap" supplied-air respirator throughout; the asbestos fiber concentrations in the air supplied to him were far belov the proposed Threshold Limit Value. Sampling and Analysis Air samples were taken by draving air through Hillipore 0.8 urn mean pore size organic membrane filters. Filters of 37 on diameter vere used for the per sonal breathing zone samples and 47 ad diameter filters for all other samples. Additional samples vere taken using Nuclepore membrane filters (0.8 vim mean pore size) for subsequent electron microscope analyses. During the simulated pipe-covering, tear-out, and bandsaving, samples vere taken at five locations vithin the teat chamber: 1) in the middle of the chamber with the open-face filter holder 8 feet above the chamber floor level ("Roof" samples); 2) from a support projecting Into the chamber approximately 1 foot from the vail opposite the work bench on vhich the covering vas done, through an open-face filter holder about 6 feet above the floor ("Room" samples); 3) above the work bench (near the vail closest to the bench) with an open-face filter holder ("Bench'* samples); 4) in the same location as the Bench samples but vith the air dravn through a Hexhlet Horizontal Elutriator (Casella-Wilson) before passage through the In-line filter holder ("Elutriator" samples); S) In the insulator's breathing zone vith disposable Millipore Field Monitors (open face) ("Personal" samples). Sample air flow rates vere: Roof, 0.7 cubic feet per minute (cfa); Room, 0.5 cfm; Bench, 0.5 cfm; Elutriator, 50 liters per minute (1.8 cfm); and Personal, 0.11 cfm. See Figures I and XI for these locations. i r r cT\ S ------------ <3 | m | H A 08 S *s n1 w*> SS S dice m ncutt ti ri \ iv* h t (iof mw) I V i r V ' -6- During the scoring operation, only two sampling locations were utilized (Rooa and Personal samples) as shown In Figures I and II. The pounding operation was monitored with four samplers, one on the bench above the product being pounded ("Bench top") and three others approximately 5 feet distant from the pounding site, 4 feet above floor level. One of these filter holders was directed upward ("Up"), another directed downward ("Down"), and the other directed horizontally ("Borizontal"). Flow rates here were 1.9 cfm for the Mass, 1.0 cfo for the three others. These location* are shown in Figures III and IV. f t t ( r V r f ( ( 6a *11 BIJOU i -7- Analysis of the collected samples was directed at obtaining tvo measures of the relative amount of duae production from the products being tested. All filters (except the 37ma Personal sample filters) vere weighed before and after use, each such weighing proceeded by desiccation for two hours to stabilise weights. From this weight data, the gravimetric concentrations of total airborne dust were computed in milligrams per cubic meter (mg/o^) by dividing the milligrams change in weight by the total cubic meters of air which had passed through the filter. This was the sole analysis applied to the "Bench", "Elutriator", and "Bench top" samples. The other sample filters were analyzed to determine the concentrations of asbestos fibers in addition to the gravimetric analysis. This analysis was by the standard method for the determination of asbestos fibers collected on membrane filters:^ a wedge of Che weighed, exposed filter was cut from the filter and the wedge (about 1/8 of the total filter) placed on a standard microscope slide on which was placed a drop of a mounting medium which matched the Index of refraction of the organic filter. The filter wedge thus "cleared" was examined with phase contrast micro scopy at 430X magnification, with the microscopic field of examination 2 limited to the area bounded by a Porton eyepiece reticle (0.0061 ms per field). The asbestos fibers seen in each field were recorded and placed into several length and diameter categories, and the field shifted to another portion of the filter. This process was continued iffitil 100 such fields had been examined, or until 300 fibers had been counted and sized. -8- Vhen 300 fibers (or 100 fields) were accumulated from any one sample, the count within the field was completed and the count then terminated for that sample. The concentration of asbestos fibers per liter of air was determined by taking Into account the area of the filter surface examined (0.0061 tan2 ), the total exposed filter area (960 nm2 ), the number of fibers counted, and the flow through the filter in milliliters. This result was expressed as fibers per milliliter (f/al). The proposed Threshold Limit Value (American Conference of Governmental Industrial Hygienists) is only for those fibers longer than 5 micrometers (ym). Therefore, asbestos fiber concentrations expressed within this report are given for both total asbestos fibers and asbestos fibers longer than 5 Um in the tables of results, but the graphic expression of fibers per ml. is limited to fibers longer than 5 yo. Specific Operations I. Pipe-covering. Three 'funs" were made on each product during the simulation of pipe covering. For each of these runs, two 36-inch long half-round sections of insulation were cut into 18 separate pieces by cutting across at 4" intervals, the major axis of the 36-inch long sections. These 4" sections were then wired in place around a 48-inch long piece of 3" I.D. cast-iron pipe so that the final covering of the pipe extended for approximately 35" (with about 1 inch lost because of saw blade width). The wired insulation was "mudded" with a mix which was constant throughout the series of tests, and the mudded surface wrapped with medium-weight canvas, i t -9- . i , " v- ^ ^ I using wheat-paste adhesive. The material removed by these operations was weighed at the completion. The wrapped pipes were air dried for at least two days and then heat-stressed. The heat stressing was accomplished by inserting Cal-Rod heaters into the pipes; current flow into the heaters was controlled by chrome alumel thermocouples (within the pipes but not touching the heaters) actuating standard temperature control relays; potential differences in the thermocouples were monitored by a multi-channel recorder which was activated for 15 minutes in each 12-hour period. Temp eratures in the pipes were held at 1150*F (+25*F) for 96 hours, with current to the Cal-Rod heaters shut off with a timing switch at the completion of that time. When all products had been applied and heat-stressed, the insulation was removed from the pipes in simulation of ship-board tear-out operations. All three pipes for one product were placed in the chamber, and the mechanic given a knife, a hatchet, and a three-minute time limit within which to remove all three coverings. Air samples were taken for five minutes, in order to standardize results, since only one sampling opportunity was available for each product. Figure V shows a schematic diagram (flow chart) of this series. i i t V L t t -9a- nans f C<wrl&f Md %r>c^t Mw Un Uf :i#l ro^uifo-i (for 1 -r *r<duei (J f*ll rai4 *Ue) full UTO9 & 6.i wLb 9.0 da e 1*.} *ln 0 6.1 Klr> JO '5 J -10- Resulcs (Pipe Covering) Tables 1-4 show the results of the air sampling for these operations, expressed as milligrams of total particulate per cubic meter of air (mg/m^), total asbestos fibers per milliliter of air (f/ml), and asbestos fibers longer than 5 micrometers per milliliter of air (f/ml 5). All concentrations have been corrected for background. The concentrations from the various products are shown graphically in Figures IV-IX, where fiber concentrations (f/ml) are given only for those fibers longer than 5 ym. r 10a Airborne Asbestos Fiber Concentrations and Total Airborne Dust (Gravimetric) Concentrations from All Pipe Covering Operations: Product A TitU 2. Ftp* Coaarlat A Ofttatlaa Ft 1/ml f/al(>5> l%u S Ldjr< 0*rl t1 m 27.2*4 27.711 s*. >*3 >1.011 >2.010 n.uo >3.35* n.iso 14.039 14. HT *1.314 17.331 17.003 14.149 14.34 3 4.400 -tJm\_ 9.34* 13.144 4.114 13.131 15.731 31.144 *7.44! *.47 leof 1.130 23.*43 XI 13.0*1 14.411 24.434 14, Ml 1.771 tmm 1*4 m,m' 20.214 4.144 4.4*4 J.17 1.334 1.341 4.934 4.922 11ml 10.241. 13.342 2.234 9.144 3.227 13.444 SjiS* 3.343 kfy Heatloa 18.304 13.778 11.494 14.434 11.101 13.4*4 14.071 13.*14 21.091 _)*.**> _J 1,417 1 1M*4. Standard 1.499 1.4*7 2.433 11.413 13.332 20.4*4 10.011 5.3*4 4.401 _ 2.503 2.443 4.721 3.034 4.434 4.444 Im f/alO3) *.144 14.191 2.102 1.745 5.170 13.041 4.041 10.31* .3 m/m 4.070 *.341 4.J03 0.4)4 0.103 5.73) 3.5)5 2% 40 m/m3 10.034 4.0)7 10.433 1.314 4.743 43.250 14.293 23.239 4.120 12.473 9.444 2.*-* 2.It 3.474 |.744_ tii_ 4.320 0.53* 1.712 1.401 0.447 1.440 0.411 tlxrltur m/m3 1.414 1.3*7 0.34* 0.479 1.344 1.511 2.271 3.121 3.292 2.147 1.27* 1.412 2.144 Taaravt 1 *9.131 *7.411 l _** ?5.1. 25.14*_ 20.374 _7j.73. _ 7.477 4.52*. 21.014 _J.9*0____ t l Airborne Asbestos Fiber Concentrations and Total Airborne Dust (Gravimetric) Concentrations from All Pipe Covering Operations: Product B Table 2. Fl Cev*ftn Froduet I OftndM _____________ J f/al (/ill 3) f/al Saaelat leaf f/all 3) mt/m3 f/al teea f/a!( 3) la4ivli| 1*2.335 142.32) 213.10* 211.7*7 241.473 302.443 230.304 39.22) Oavlatlaa 121.04* J 134.477 17*. 759 1*0.524 : 202.*10 ; 243.474 1 110.290 ) *3.3*7 42.349 223.134 134.853 10*. 344 97.400 130.413 34.420 217.147 147.279 92.17* 193.149 137.047 127.074 "5.47S" "iS.l07 "1C74* 9.73* 13.31* 1.104 17. sr 24.931 -- 13.44* T*i7 *5.0)5 149.747 23.274 19*.433 101.402 104.410 10*. 3*1 41.U0 ` 37.937 133.403 21.479 1*3.7*4 90.4*2 97.475 44.504 37.3TO KfflltKlffl 37.133 114.373 15*.140 Htan 113.147 itiMiil 31.441 0-fat(*n 49.701 104.1*2 233.344 *3.04* 34. *02 3*. 735 30.417 42.03* 7.474 30.342 34.41* 4*.731 *.5)3 20.140 10.774 13.479 11.477 1.744 23.031 32.044 34.04* 32.IH4 7.074 14.8*7 17.001 33.327 27.4/M 7.72) turt 2*2.021 241.345 71.477 *9.122 19.134 1)7.94* 1)2.144 Untt 1'.* W'-> Zlutrlatar >0.113 17.4)2 2.474 13.12) 7.*15 14.33) 10.444 1.111 4.377 13.247 14.432 3*.307 19.37* 9.912 17.431 irmr 2.7)3 1.4*4 *.247 17.4)7 3.37* 21.04* 1.120 17*90 1.353 9.*41 9.44* 7.134 3.903 7.474 *.7*3 __ f .40* 0.S20 0.410 1.282 2.779 7.*41 1.4*7 3.4)7 ' 27.2*9 33.370 3.713 V i r i t 10b Airborne Asbestos Fiber Concentrations and Total Airborne Dust (Gravimetric) Concentrations from All Pipe Covering Operations: Product C f/K>3) 5.4*3 ls.sie u.iii 11.10* *.344 Stn4t4 J.I10 Pl*< f 1 rm 5.415 11.741 10.5*2 11.023 *.443 .057 2.1*1 Application Str>4r4 5.131 5.*22 7.837 .*.52* 1.154 ... *. * 52 4.245 5.172 o.*;* T**r**t | 13.5*5 12.524 Tiki* v Fir* C*irlnc U,uU t f/fttl tecf f/l(>5) 1 /.' 1.102 3. 322 4. *53 5.084 3.541 4.083 3.74 1.1*5 1.77* 2.851 4.443 4.811 3.2*4 3.*78 3.544 1.141 4.528 8.04* 2.05* 11.181 t. *05 10.131 7.045 3.80* 0.883 2.481 1.3*4 4.50* *.128 3.002 3. *18 3.81* IftOi f/*lt> 5) 0.831 2.2*8 3.181 3.79* 3.110 3.005 3.280 1.474 taeh 4.337 4.5*2 1.442 3.4)7 7.808 4.244 4.347 3.077 2.413 0.085 0.20) 1.184 10.534 4.78* 3.821' -*/>- - 0.805 0.441 2.44* 0.383 5.000 30.201 ___ 11.4*0 5.412 5.502 2.50* 4.44] 1.172 5.823 5.280 2.54* 4.514 1.807 4.444 4. *71 17.828 8.011 7.4*5 1.820* 7.504 5.11* 4.*03 3.712 1.747 ' 4.118 4.878 4.572 2.557 3.7)4 3.412 9.4)0 4.1*2 1.0*4 1.481 4.12) 4.840 . 4 J4*_ 2.875 0.848 J.434 1.418 __1.J01 0.402 1.1*3 1.328 4.527 5.383 5.025 *.583 33.1)4 1.3*4 Airborne Asbestos Fiber Concentrations and Total Airborne Dust (Gravimetric) Concentrations from All Pipe Covering Operations: Product D Operatic* Kjc^ttvUft *)( !* tftplUKlN 0vU(lM Turwt fr i/ml (/!( >3) 28.05* 31.01* 50.384 2274..27**88 28.378 27.525 24.147 34.31* 41.948 32.484 >4.828 7* 1*7 5.142 4.87| 20.287 18.180 28.574 25.84) 21.17* 72.214 4.204 737..5345)1 4*.742 43.841 mu *. ftp* m*iu frWwct t teef /!(,)) 1.148 25.748 3.308 13.3*8 2.842 22.204 ft ?ft 8.050 1.802 73.451 3.201 13.1)8 2.474 10.458 ft.155 8.474 __ bslii n/.1 0.374 3.274 13.4*7 3.7*3 1.082 3.001 4.501 5.347 r/i 5.357 4.244 10.314 14.032 1.784 4.074 8.470 4.352 Um /l(4) 4.48) 18.62* 8.111 13.453 7.58* 3.170 8.8)5 3.877 2.044 4.32* 4.054 40.251 13.454 10.578 12.77* 14.08* tone* */' 8.74) 7.148 10.034 13.300 1.340 32.321 12.35) 10.382 20.5*0 74.300 18.110 2.1.38 7 2.481 18.4*4 24.177 11.57* 2.878 11.1)3 21.72) 14.48) t).7lt 5.404 7.2*7 11.127 ll.Oft* 12.144 5.477 23.40* 7.352 10.5)3 11.738 17.58) 14.854 H-2JU 4.5)3 11.315 3.74* 7.320 4.328 5.442 _}1*.247I21 41.001 38.414 74.84* 22.311 11.744 8.84) 33.134 (lutdtut /' 4,808 2.51* o.m 3.872 4.253 4.348 3.4*2 2.0)0 2.7*7 2.57) 3.255 5 558 1.4*1 1.7*2 ( V t t ( ( t C ( 1 < 10c -f 1 1-- * ----------------I---------------------1______________i_____________ i_____________ i * sa sa s t H 4 r ( C *Oj J< : X4>1 ' <n ` 4) - CuO P v Ke UWHl Tc- 3 *E4 To > Ic oU 3 V et JotO ct(. 3 w*4J c 4k- Ho us 3vj. T o ta l A irb o rn e Dost (C ra v ira e tric ) and A irb o rn e Aabeaton F ib e r C o n c e n tra tio n s : A p p lic a tio n P o rtio n o f P<n r -10dr i ( i * i r-o- u ( E6 I 8C I til i ( 8 8S3 o ( ( i4 f t ?! f : K u l! E s I ( >------- -4t --.....< >-*--I f-t u j i 6 40 J'h ) i >- - -4 1 -4 9 r 4 -lOe- T o ta l A irborne Dust (C ra v lm e tric ) and A irborne Asbestos F ib e r C oncentrations: Tesr-O ut P o rtio n o f Pipe Covering / ./ ,^ ( t l < < -11- II. Power Saving (Bandsaw) Six 3-foot long half-round sections were cut Into (approximately) 4-inch long sections (making 9 cuts per 3-foot section), using a Devalt bandsaw with a 1/2-inch blade with 6-blade points per Inch. Ihe linear velocity of the point tips was about 3000 feet per minute. A background sample was taken before each product change. The saw was placed In the center of the room (under the Roof filter holder). TVo half-sections were cut. while samples were taken, then the saw shut off and the filters changed. This process was repeated twice more for each product. Figure XII shows a flow chart for this operation. |A*B SAVtMC ncutz zu Hut Tt* t.'ulrM (far 1 full Metis*) A 2.0 *ia. I 2.1 ill. C 2.2 iti. D 2.9 U. Air Sm.la. Nr fr4uci IS ^ ( ^ f I t [ i l V. Results (Bandsaw) Table 5 shows the results for the bandsawing for all products with (again) the results listed as total asbestos fibers per milliliter, fibers (longer than 5 Un>) per milliliter, and total particulate milligrams per cubic meter. In Figures XXII and XIV are again shown the graphic representations of results, Airborne Asbestos Fiber Concentrations and Total Airborne Dust (Gravimetric) Concentrations from Bandsawing: All Products TKlt 5, ntf Scvttft ttyultl Pron* 1 f/*l f/mJ C>5> (/l f/*lf>5) /*5 t/mi loot f/slOS) o'*1 6,nth n'v tlucrla(*r o'.1 * $(n4r* 74)04? 225.615 174.757 ? t*.. n* u.ui 754.262 217.7O0 170.452 207.4*5 J2.8/1 4.404 172.>44 114.175 40. M 0 64.203 3.t70 117.0** iot.>#t 74.M2 65.255 2.11) 35. 385 31.211 73.1*7 17. 74 J 101.571 104.420 41.271 101,4*0 4.046 103.771 44.540 14.731 *7.6*7 7.704 23.004 26.073 74.035 41.770 76.451 144.424 147.314 142.041 1A5 J3i_ 2.421 18.461 0.323 27.074 14.441 13.547 t Sl*ft4r4 362.0?* <**.731 uji.m 1070.78? OS*. 101 75*. 7*2 407.326 374.224 26S.243 347.770 324.004 3V>. 47* *6.247 2 3t. H 7 371.374 n>. jt> >0*.4<7 6S.44> 34.14) 101.471 161.674 47.44> 13*.161 300.>*4 276.31* :)*'.2*7 17.642 135.044 241.474 264.6*1 2)2.754 14.677 30.650 >4.71? 74.000 47.16* 23.341 174.441 166.434 155.744 1 77.284 15.472 74.54) 40.4)7 34.474 35.434 5.555 C Maafl St*nd*r4 OrrlttlWl 0 NfUtln 51.072 it.221 40.6*1 *3.480 >.220 tl.MO 27.475 61.441 51.ISt 21.351 47.470 41.322 >6.440 *1.144 >.712 41.47S 23.147 75,141 >3.414 24.471 31.404 24.204 4*.4*4 33.3>t >.041 30.453 21.44) 3*.6? 32.17J 3.405 264.617 664.642 ***.574 >34.427 732.344 It.>44 17.201 44.MJ 43.174 44.lit 17.42 17.074 43.114 42.544 43.1)4 14.226 35.171 146.372 1.424 44.443 33.501 24.011 2*.*1 30.477 2.620 45.744 22.177 53. >33 40.503 14.335 32.44) 27.275 26.371 21.744 3.400 26.450 75.754 172.7)5 75.640 47.143 220.640 224.307 122.274 1*0.661 34.371 31.113 11.772 70.120 21.004 4.700 45.040 21.026 31.5*4 34.151 16.004 4.473 34.130 60.45* 30.340 27.440 151.341 34.124 241.274 141.444 130.344 26.514 5.047 34.545 12.727 14.150 t ( < l ( IS 5 4 ** 12a 4 >4I M * T o ta l A irb o rn e Duet (G ra v im e tric ) and A irb o rn e III. Power Saving (Scoring) Two 3-foot half-round sections were scored to s depth of 1 1/4 Inches, to simulate the scoring of flat blocks of insulation, as is done to facilitate the thermal Insulation of large vessels (e.g., boilers) with large radii. Each section of the insulation was scored longitudinally four times while samples were taken; the filters were then changed and the process repeated. As above, a background sample was taken with each change of product, and an additional personal sample was taken during the clean-up process. This was done using a Ram hand circular saw ("Skilsav" type) with a 7-inch diameter blade with 1 blade point per outside circumference inch. The linear velocity of the point tips was about 3000 feet per minute, as it was for the bandsaw. The flow chare and schematic of this operation are shown in Figure XV, ae canto ncuu xv Aw fr Air iwflii fr >rMvt A 2.4 tin. 2.2 C 2.1 aln 6 1.4 a*. 14 Results (Scoring) Table 6 shows the scoring results, Figures XVI and XVII their graphical representation. Airborne Asbestos Fiber Concentrations and Total Airborne Dust (Gravimetric) Concentrations from Scoring: All Products Ttl I. krlt lutlu Froriuct Mneul SM>U( (/ml i StauUr* OavtatLa* *44.314 311.4*4 411.64) 4*0 1H 1*6.111 1161.441 mi.m 1*41.144 1166.401 >(tdir4 6* v< * 11 of> 1*41.1*6 416.1* 1)1.411 *74.744 114.0)1 3)4.616 441.716 14). )64 1)41.411 1)11.41* IV*.> 6* 1152.1)1 i4n.no 444.81) f/ml (/!< 101.140 44.117 1)1.074 7.171 , 141.4)7 41.411 124.484 *1.110 13.4)4 41.SOI 115*7 14.147 7 44,47* 1*3. 1)1 74).*)$ 44.714 722.147 *01.224 741.48* )). 414 SI.Ml 247.2*2 L-114.631 151.4)4 C tondird 11.40* *1.1 w 14.664 .IM IS.Ill 11. SO* SO.Ill 41.14) 44.067 14.440 47.4)4 14.7)7 It.Ill 2).4*4 22.7*4 7.1)7 14.011 24.174 _____ IL Li?__ 7.24) 10.1*4 44.764 31.367 34.477 e *10 StndM (HvltliM 104.44) 174.4*1 1*0.m 1)0.16* 701.S4* 11.0)1 iff. m 141.4)6 171.771 728.7*0 1*1.70) 14.1)1 SO .02) 47.44* 71.4*4 11.4* 47.00* 4).If) 71.ISO 14.144 10,601 4.10) 17 7)4 4.40) V 1 14a r, *T i *r t2 & v& X Il l j___ :iiI I HI ---- *I I |3 Te > *- | |$ .4 a 5 *r- a t * T o ta l A irborne Dust (G ra v im e tric ) and A irborne Asbestos F ib e r C oncentrations: S coring -15- IV. Founding A 4-inch section of insulation (recovered from the Bandsawing) was placed in a 4-inch wide by 9 1/2-inch long by 12-inch deep (internal dimensions) box, and a 4-foot long section of 1/2-inch (I.D.) iron pipe (weight 4 lb. 2 or.) dropped through a guide section of 3-inch pipe a distance of 16 inches onto the rounded outer surface of the pipe covering. This drop was repeated 50 times, and then the pumps started and 5-minute air samples taken. The process was repeated twice more, using the same piece of pipe covering throughout for each product. Aa usual, background samples were taken with each product change. Figure XVIII shows this experimental arrangement; the locations of the air samples are shown in Figures III and IV, p. 6a. flam nu A A `ft I U' 1 13 ' Flat f M U4 In -16- Results (Pounding) Table 7 gives the results from this experiment, as do Figures XIX and XX. Airborne Asbestos Fiber Concentrations and Total Airborne Dust (Gravimetric) Concentrations from Pounding: Ail Products- THt 7. 4r*8st n/.J A Mas Jutdird Barlatlra 2.450 4.417 2.410 5.214 1.020 Ma Ua*4at4 Ovrla (Isa 2.570 2.570 10.708 5.544 l.Ul Mam StiMird Dartatlaa 4.283 2.283 4.447 J. 553 1.74ft Mait 8cn4ar4 6a*ltta 5.441 1.J71 0.44) 1.452 1.555 ImUi 9*. Oew, Mrltmtal /) (/l f/ml(>5) 1.040 1.485 2.554 5.444 2.544 54.4 2 5 1.442 5.054 4 4"7 11.477 2.104 7.402 8.247 2.541 4.144 4.434 2.814 4.7)1 5.415 S 474 2.470 2.458 7.807 4.5*4 10. Xil 2.475 5.104 5.088 10.152 5.*24 5 1 5.004 ... . . 0.243 1.001 0.445 0.445 2.482 0.245 2.415 1.054 5.708 44.844 24.140 55.417 47.755 24.804 23.408 44.888 57.818 41.822 57 rtn 47.413 51.417 37.447 44.44? 28.7)7 27.8)7 44.425 >4.233 43.152 5* ------ V827--------- 0.280 2.244 0.034 4.45$ 0.280 1.424 5.424 0.45) 0.455 1.414 1.424 0.137 5.811 8.171 3.104 8.832 7.544 8.518 8.144 0.554 4.118 1.721 0.825 1.114 1.518 2.827 1.452 2. 544 1.14 5 1.557 1.552 0.581 5.487 2.214 5.041 4.514 2.4?) 2.848 5.224 2.045 5.53? 1.827 1.018 2.0)1 1.412 2.450 2.144 2.423 1.581 1.473 1.524 0.32ft 5.421 2.148 5.271 4.440 2.44) 2.144 5.454 2.744 5.5*4 5.412 1.110  -16ai t l r t i c 1e r w 4 t*| ( f / a l J) T o ta l A irb o rn e Duat (G ra v im e tric ) and A irb o rn e Asbestos F ib e r C oncentrations: Poinding -17- Discussion of Results It is clear from the foregoing results that Product B produces significantly more airborne asbestos fibers from similar manipulations than any of the other products. This is shown by Figure XXI, where the ranges and means of all results (except those from the scoring) have been accumulated. ftt til l**>t'* *4 H*Mi* (txttpt esrtj) ncvu m \ m Ttcovcn -18- One question which has not yet been answered is: `Vhat are the sizes of the airborne asbestos fibers produced from these products?'1 Answer to this question is provided by an examination of the diameters of the asbestos fibers counted on the Personal filter samples for all products, (for the hand-saving portion of the pipe-covering operation) in Table 8. Table 8 Asbestos Fiber Diameters from Personal Samples Product 50% less than (geometric mean) 90% less than geometric standard deviation A 1.45 Pm B 1.7 pm C 1.6 pm D 1.6 ym 2.8 pm 3.0 pm 3.0 pm 2.9 pm 1.66 1.59 1.60 1.56 Another concern which arises from an examination of the data is with the total gravimetric concentrations of airborne particulate matter which were measured. In many cases, these were orders of magnitude above the proposed Threshold Limit Value of 10 mg/m^ for inert dusts. This indicates that, even if these products contained no asbestos, their use in enclosed spaces similar to our test chamber would produce concentrations of airborne dust which would be unacceptable. Analysis of the ''respirability11 of these dust concentrations (from the comparison of the Elutriator samples with other samples) is proceeding and will be the subject of future publications. It must be understood at this point that the results of this study are ( V c ( ( < k ( c < < -19- subject to several qualifications. Perhaps the most important of these is that exposures of workers in the actual application and manipulation of these materials would often be different than those found here. Higher concentrations would be postulated if several men were working within an enclosed space, or if the available space was more confined. More likely, actual concentrations (as ve have measured in many diverse Job situations) would be lower due to slower pace of the work, natural ventilation, or greater space available for dilution. Another qualification is that the Pounding and Scoring operations performed here are not strictly comparable to actual trade practices. The pounding operation was (in essence) a destructive test; most applications would not be accompanied by repetitive blows concentrated on a small area of the surface of a product. However, (despite the fact that this is considered a poor trade practice) some insulators will not consider an installation complete on a large vessel until they have thoroughly pounded the applied insulation material, raising clouds of visible dust. Scoring is ordinarily done to facilitate ''bending" of flat blocks of insulation to fit a curved surface. Product B is not supplied in flat blocksi and it ia therefore unlikely that scoring will be done to this product. But mechanization is proceeding in this trade (as In others) and the use of power saws of various sorts is becoming more common for tasks which have traditionally been done by hand. A third Important qualification affecting the application of the results found here is due to our sampling method. None of the data are time-weighted average concentrations; they represent "peak" exposure*. Nevertheless, the relative hazard judgements implied by the different concentrations found are valid, since the time limitations were Imposed by the products themselves. That is, a product which ia easier to work will require less time for installation of a given segment, but in actual practice this will mean that the insulator will install more of these segments. He will thus be exposed to more repetitions of peak exposures, not necessarily to a lover time-weighted average exposure. Further, the purported ease of fabrication of Product B was not found in our tests. This can be seen from the times shown in Figures V, XII, and XV. It is worthy of particular note that Product B was the only product for which the 3*rainute tear-out time limit was not met. This was due to the "springiness" of this product; the wires rebounded from the hatchet blade Instead of breaking cleanly. Our hypothesis that the product containing the highest percentage of asbestos might not produce the greatest concentrations of airborne asbestos fibers has not been validated by this study. From the raw data, it would appear that our conclusion must be: "The concentrations of airborne asbestos fibers are directly related to the percentage of asbestos in the parent products." Ve do not believe this to be a general rule; we suspect that design of materials to reduce airborne dust production is possible and that factors not apparent to us at this point may eventually prove to be of more Importance in this design than the percentage of asbestos. Our examination of the products used in this study is continuing; we hope at some future time -21- to be able (within reasonable bounds of certainty) to predict airborne asbestos fiber production from given operations on specific products. This prediction would arise from consideration of such factors as density, relative strength of the bonds between the asbestos fibers and the matrix, resistance to specific kinds of applied forces, and others. From a practical point of view, it is clear that none of these products should be used without industrial hygiene control. Any cutting operation should be accompanied by controls on the dust arising from that operation, preferably controls (such as local exhaust ventilation) which would prevent the dissemination of dust into the breathing rone of the workman doing the cutting, or the breathing 2ones of those working near him. Where this cannot be done, personal respiratory protection is a poor (but necessary) * second choice. Conclusions 1. A method by which construction materials can be tested for their potential for airborne dust generation has been developed. 2. Four insulation materials containing asbestos have been tested using the method; the material containing the highest percentage of asbestos produced the highest concentrations of airborne asbestos fibers under conditions of the test. - 3. Measurement of the total airborne dust concentration is a "poor" indicator of the airborne asbestos fiber concentration. 4. Comminution (by hand or mechanical methods) of any of these products within confined spaces may result in airborne asbestos fiber < f ( C ( r < i 4 t / 1 i -22- concentrations orders of magnitude greater than the proposed ceiling value of the Threshold Limit Value. REFERENCES 1. Durban, T. M.: 3rd Symposium on Silicosis, edited by B. E. Kuechle, Employers Mutual Liability Insurance Co., Wausau, Wisconsin, 1938, pp. 66-69. 2. Drinker, P. and Hatch, T. F.: Industrial Dust, McGraw Hill Book Co., New York, 1954, p. 83. 3. Balzer, J. L. and Cooper, W. C.: The Work Environment of the Insulating Worker, Aaer. Industr. Hyg. Assn. J., May-June, 1968. 4. Lanza, A. Z.i Asbestosls, J.A.M.A. 106:368-369, 1936. 5. Selikoff, I. J., Churg, J., and Bananond, E. C.: Asbestos Exposure and Neoplasia, J.A.M.A. 188:22-26, 1964. 6. Edwards, H. and Lynch, J. R.: The Method Used by the Public Health Service for Enumeration of Asbestos Dust on Membrane Filters, Annals of Occ. Hyg. 11:1-6, 1968.