Document R2aMJJ300Kj5Vv1e5Y12erYj8

Authors Fred W. Boelter Gary N. Crawford Daniel M. Podraza Bocltcr 5; Yates, Ine,, 1300 West Higgins Road. Pari; Ridge, !L 60068-5772 Airborne Fiber Exposure Assessment of Dry AsbestosContainina Gaskets and Packin Found in Intact Industrial and Maritime Fittings This study assessed airborne liber exposures from intact asbestos-containing gaskets packings while activities representative of historical work practices were performed. Tb design eliminated analytical interferences while systematically capturing information ret activity variables. A series of gasket and packing activities was conducted according h traditional methods while sampling was performed to determine the 8-hour lime-weighl average ffWA). The fittings used during this study were obtained Intact from a decommissioned industrial power plant and U.S. Navy destroyers. The activities tested flat blade scraping, hand wire brushing, power wire brushing, making gaskets with a b hammer, and stem packing removal and replacement. All activities were performed dry lor every area and personal sample showed the 8-hour TWAs were well below the cur Occupational Safety and Health Administration permissible exposure limit of 0.1 f/cc. A database of more than 400 points was developed to analyze information from variable related to the tests. These factors included, tor example, type of gasket, composition ol gasket, percentage of gasket adhering to a flange surface, gasket surface area, and m elapsed for removal. The results demonstrate a very low rate of fiber exposure from rot activities associated with asbestos-containing elastomeric gaskets and impregnated pac Keywords: asbestos-containing, exposure assessment, fittings, gaskets, packing, i This project was Rinded by Coitce Industries. sbestos fiber exposure assessments are prevalent and newly manufactured pros! Adifficult to conduct with .? high degree still used around the world. Gaskets ami f of' confidence for specific products when are not banned by the July 1989 U,$. h either asbestos or tmnashesiox fiber con mental Agency (EPA) final rule regard tribution from other sources must be caremfiraifvnufacture, importation, processing, a managed such that they do mr complicatetrtihbeunon of'asbestos products. Asbest interpretation of analytical results Elastomeric ; gasket and impregnated packing material often 1 contain high percentages of asbestos, and an e\| posure assessment is difficult to determine in earning gaskets and packings are the pm choice in many applications such as el planes, refineries, power plants, and ships The published literature contains litrh mation representative of historical or tr.u field applications because of the presence ofdusts work activities involving asbestos-containi and fibers such as from clothing and other in kets and packings such as the practice of sulating materials such as fiberglass and asbestos mm.il. Most of the literature reports on Assessing the exposures resulting from han of specific activities to determine cotnpl dling asbestos gasket and packing-materials is ini noncompliance as opposed to exposures portant because prcuouslv installed products arc mg from dry handling and worst ease see 782 AIHA Journal (63) N'ocemhef/Deceinlxcr 20U2 Copyright 2002, American Industrial Hygiene Asso Historically represent.unc viatj is important in conducting expo sure and dose reconstructions and in comparing historical expo sures against those related to today's "good seorfc practices " Other investigators lute attempted to measure worker expo sure resulting from the handling or manipulation o! asbestos-con taining gaskets and packings. The U.S Navy studs- by Liukonen ci a!. * and two other studies published in journals were coo* ductcd in the Held of svorkers under actual conditions. In the field study by Cheng et a!.`4' tests were performed while the gaskets were drv cut or removed under both wet and drv conditions. There are relatively tew data points associated with the removal activities. In the Held studs by Spence et a!.'5> a comprehensive senes of tests was performed while the gaskets were removed while being wetted, whereas traditionally these techniques arc performed dry The investigators utilized transmission electron microscopy (TF.M) in accordance with National Institute for Occupation Safe ty and Health (NIOSH) method 7402''' to distinguish asbestos libers from interfering nonasbestos fibers. The investigators con cluded the phase contrast microscopy (PCM) overestimated as bestos liber concentrations in their study, even though the PCM results ranged from he low detection ro 0.02 fibers/mL. One potential limitation of all the field studies was the as sumption that the fibers counted by PCM ' were all asbestos. Kven il rhex were determined to be asbestos, an assumption would still need to be made that the counted fibers actually came from the respective gasket nr packing being handled and not from some other asbestos fiber source. It has been the authors' experience that in conducting field siudies manv variable conditions cannot be controlled; oficn con dition.s can onlv be recorded and reported. Simulated work envi ronments mav bas e the benefit ot reducing the number of degrees of freedom be controlling or eliminating certain variables. Three other published studies on gaskets and packings were pcrlisrmed in simulated work environments, In the- simulated work environment study hi1 Fowlerv testing was performed while band saw cutting gasket material l his was noted to be an unusual prac tice and therefore is ot narrow or limited case-specific interest. In the simulated work environment studs' bv McKinncrv et al 4 ac tivities were performed in ways not represemam e ol gasket acmitics observed m the workplace, jik! the analytical procedures were misused. The simulated work environment study bv Milleite et al, liieused onlv on the dry removal ot packing and also misused the TEA! procedure. A common problem with simulated work environment studies when definitively idcntitying asbestos fibers has been the use ot direct or indirect preparation lor TIM analysis utilizing "cleanliness" Asbestos Hazard Emergency Response Act of IbRfs (AHEH.M " or nonoccupatiotial EPA,I; International Organization tor Standardization ( LSOj,1''-11 or ASTM"" analyt ical protocols rather than the prescribed direct preparation N'lOSH THM method 7402 When NIOSH method 7402 ssas used, ii sijs incorrectly used as a counting technique rather than as a technique lor determining the percentage of asbestos fibers present. The asbestos fiber concentration in air is to he calculated by multiplying the NIOSH 740(1 f'CM total fiber counts bv the ncrcciir.ige ot' asbestos tillers determined in the NIOSH 7402 1'EM analysis Additionally, in all the published studies the respective lines Ogjtors either sampled specific short duration tacks tor comp.tn son against a short-term exposure limit or projected, through cal culation. a time weighted average (TWA) tor comparison against the permissible exposure limn < 1'Hl.i ""nr threshold limit value. There are, therefore, limitations to both the He Id ansi simulated work environment studies ill determining fiber release fur use m exposure assessments and historical dose reconstructions The purpose ot this study was to carefully conduct a studs of elastomeric asbestos-containing (fibrous) gaskets and impregnated asbestos-containing (fibrous) packing materials to determine the exposures that result from rcpica! activities. For the studv a [extinct protocol was developed tor assessing personal exposure to fibers and general room air concentrations xvhile conducting fixe differcm but commonly encountered activities. The five different activ ities evaluated included flat blade senping, hand ware brushing, power xxarc brushing, making gaskets with a ball-pecn hammer and stem packing removal and replacement. The objectives were to (I) utilize common techniques for han dling gaskets and packings and facing flanges; (2) handle the gas ket and packing materials in the wav workers traditionally handled them; (3) perform tests at a rate typical ot workers in the field; (41 conduct the testing without wetting the gasket or packing materials; (5) perform the rests in a controlled enxironment to eliminate interfering fibers and thus the need for fiber identifica tion or confirmation by TEM; (6) utilize fittings from the field with a known history; (7) conduct the tests in accordance xxith good industrial hygiene practice; and (8) carclullv document the variables associated with the testing and findings. METHODS Intact fittings were identified and removed trom two different settings; industrial and maritime. The fittings and flanges select ed had been in service manv vears and were obtained from a de commissioned power house or decommissioned U.S. Navy de stroyers. Each fitting was rigorously cleaned prior to use in the studv. An isolation test chamber shown in Figure I was constructed in which to conduct the study The chamber was 20 fit wide bv 20 fir deep ami 9 It in height. It was constructed of two separate n ails ol 0 mil polyethylene .sheeting to physically separate the ac tivity being tested from outssde-rhe chamber influences A work bench and hoist were placed in th: center of the test chamber. The purpose ot the chamber was to assure the elimination of fiber influences unrelated to the fitting gasket or pjckmg. The chamber was designed and constructed to be a static en vironment During the test there was no air movement into or out ot the chamber This was verified bv smoke tube examination trom the outside and bv carbon dioxide monitoring during the testing. ( arlson dioxide concentrations usually stjrxcd at 000 ppm at the beginning <>t the test cycle and peaked at 7000 to 8000 at the end of the test cycle. During the cleaning following each test cvcle, the room was x-cntilated with high-effieicnex- particulate air i HERA; filtered air being pushed into the chamber and air being drawn out of the chamber through another HERA filter. Entry into the chamber was onlx through an access airlock. Between testing cycles the isolation chamber was ventilated, systematically wiped down, and determined to be clean bv AHf.RA aggressive .ur sampling protocol, The studv was conducted as 10 separate cedes in an isolation clumber to eliminate outside influences Each cvcle svas conducted at the rate of one fitting per hour over an 8-hour period. The frequency ot one rilling per hour wax based on the activity rates observed bv the authors, reported in previous published field gas ket studies, and those in reference estimating manuals ' or ref erence text bonks. ' Some 80 fittings with flanges ranging in size from 4-12 inches A1HA Journal (63) Novemher/Dcccmbcr 2002 / .x.x in diameter and weighing from 2-200 pound* were used during the 10 testing cedes. During a particular testing cycle (i.e., power wire brushing an industrial fittingl a different fitting was handled each hour and us gasket removed and Its flanges laced in a similar way. Eight fittings were thus used lor each test cycle. About 30 industrial fittings with a total of 50 Manges and 20 valve stems were assembled lor the industrial phase ol the testing About 20 maritime fittings with a total of 40 Manges and 10 valve stems were assembled tor the maritime phase of the testing. Phw leal information about rhe fittings was recorded Tins included sire olihe flange, number ol bolt holes, size ol the bolt holes, and so forth. All the fittings had intact gaskets as well as valve stems. In preparation for the testing rhe linings were caretullv blasted with glass beads to remove surface corrosion, rust, paint, insulation, and so forth. The gaskets and packings were left intact. Based on the careful room preparation plus systematic cleaning and han dling of the fittings, there was a high degree of confidence that the orilv fibers in the test chamber would be a release by the re spective gasket Or packing activity hemg tested. The first five test cedes conducted used "industrial fittings" from the decommissioned power plant. Test vvcle I was "Fiji blade scraping." test cycle 2 was "hand wire brushing," rest evcle 5 was "power wire brushing." rest cede 4 four was "making gas kcis ss tth a ball peen hammer." and test cycle 5 was "stem packing removal am! replacement " The nest five cycles conducted used "maritime fittings' from the nasal descrovers. Test evcle 0 was "flat blade scraping," test cycle 7 svas "hand svirc brushing," test cycle 8 was "power wire brushing," test cycle 9 was "making gaskets wnh a ball peen hammer," ant! icsi cycle 10 was "stem packing removal and replacement-'* Each lumr dunng the cycle, one of the eight fittings was po sitioned in the center ol the room on the work bench ("cycle event" i. The fittings selected for the particular test evcle were all placed m the isolation chamber before beginning the test cycle. A total ol eight "evcle events" w ere conducted dunng rhe course of a test cycle which fasted 8 hours. A total of so test cycles com posed of 4K cycle events were conducted during the gasket re moval and Mange "facing." The other four test cycles related to gasket making and packing removal activities The gasket removal and flange "facing" procedures used dur ing each of the individual eighi hourly "cycle events" were con ducted m the same manner until the particular flange was "faced" ami adcvjiutelv prepared as if to receive a new gasket. The author and helper performed rhe procedures by trades such as pipefitters and mechanics following traditional techniques reported in the published literature and personjilv observed by the author. The gaskel iniu.illv was removed with a flat blade scraper and the flange was faced with the respective finishing technique (flat blade scrap er. hand wire brush, or power wire brush! All gasket and packing removal and replacement procedures were conducted drv In Fig ure 2 an industrial fitting is shown being faced with a power wire brush ()nlv fittings containing fibrous gaskets that appeared to he 734 AIHA Journal (63) Novcnihcr/Dcccmbcr 2002 ! FIGURE 2, Flange of *n industrial lining being "laceo'' wltn * power wire brush asbestos-containing and elastomeric (i.e., flexible! were used in the study. Dunne each evele even! this was determined visually when the flange wav actually opened, .is shown in Figure 3 Gaskeis tli.it Mere not elastomeric lie,, spiral wound msrall were rejected, and .mother fitting was selected ttjr that event cycle, The necessity to reject ,t fitting occurred nnlv three times in the course of the -IS event cycles when a gasket was being removed. All of the gasket and packing material renamed was fibrous Alt materials were re tamed and tested tu verify asbestos content. When old gasket ma terial uas determined to contain asbestos, content ranged from 40 to 80% ehrvsotile. There si ere no eroctdolite gaskets encountered. The gasket-making sampling and event cycles were conducted identical!'' to the methods used in the gasket removal and flange "facing" tests except that a new gasket was made. A fitting was selected that had been ''faced" in a previous gasket removal test. New 1/16" thick Ciarlock 900 gasketing, which contains 60 m 8U".i ehrvsotile asbestos, wax obtained and used tor the event cvcl.es. rise 16 new gaskets were made using a ball-peeil hammer, as cli. u li in (figure 4. The packing removal ami replacement sampling md event cv vies were conducted identic-alls' to the methods used in the gasket remm.il and flange "faetng" tests except the ' .'lie stem packing " As being removed and replaced. Removal and replacement of'.the. stem packing for a particular fitting occurred during the same evele (Gar luck Sealing Technologies. Palinvra, N.V.l. A valve was se lected and the old packing was removed (see Figure 5) and the stems were repacked with new asbestos-containing packing ma terial. The old packing materia! was all fibrous, and when it con tained jsbexios, it varied from 40 to 80% ehrvsotile, The "new" asbestos containing packing material used tor the event cycles was from unused new old stock (N'OSl This material was Garloek 5tvle 733. which is a graphite impregnated .80% ehrvsotile square braid ed packing. The 16 valves were packed using new valve packing tools purchased from a catalog. Personal samples were collected using OSRA monitoring methods in accordance with gixid industrial hvgiene practice.-1 Personal samples were collected Irmti the breathing zones ot the tvvii individuals performing the work tor the duration of the 8 hour test cycle. Samples were collected and analyzed bv PCM fol lowing O.SHA ID 160, which is essentially the same as N'lOSH method "400, A Rules. ' To eliminate variability, analysis' was per formed by the same analyst at the same laboratory accredited for PCM analysis by the American Industrial Hvgiene Association. Persona! air samplers vsere started at the beginning of the S-hour test evele and were stopped only during the lunch break. To determine tile general room air concentration, the isolation chamber was subdivided into 3600 modules of 1 ft" each, and each module was assigned a discrete Consecutive number for pur poses of identification bur each evele a random number generator was used to select 8 ot the modules lor sampling, A sample cassette was located in the center ot the randomly selected module for the duration ot the evele, and samples were collected ansi analyzed AIHA Journal (63) Novembei/Decenibcr 2002 735 FIGURE 3. AHir opamng tn* !t*ng, tt> jMktt wi first verified >> *n l*lom*ric ityls. following NIOSH method 7400, A Rules. General room air sam plers w-erc started at the beginning and were run during the enure 8-hour test cycle. Prior to each test cycle the room teas verified to be "clean" following "aggressive air" clearance monitoring protocols using a lea! blower and tans. The room cleanliness was verified as <70 s/mnv bv collecting five air samples inside the chamber and an alyzing them according to EPA AKERA, Appendix A, Post Abatement Clearance TEM protocol. "' To eliminate variability, analvsis was performed bv the same analyst at the same lahnraton accredited tor TEM analvsis by the National institute ot'Sundards and Technotogv (NISTi under the National Voluntary Laboratory Accreditation Program fKVLAP). When possible prior to selecting a particular titling for studv, the presence ot'asbestos m the gaskets svas verified; however, this was not possible to determine for every fitting. Because it was important to maintain the integrity of the gasket to flange face, a small pinch of gasket material was removed from the flange face gap without opening the llange After the gasket removal cycle was completed, the removed gasket material svas reserved, and a larger bulk sample w as collected and analyzed. In addition to the old removed gasket maicnal. bulk samples ot the new gasket ma terial used in the cvcles in which a ball-peen hammer was used to make gaskets were collected and analyzed, Bulk samples were an alyzed bv polanzcd light microscope tPLM) following EPA AHP.RA. Appendix E. " .Analysis was performed bv a laboratory accredited for PLM .analysis bv NIST under NAT^AP Sampling results were formatted in a database for analysis Sta tistical rbiKumis were performed including maximum, mean, min imum, and standard deviation. Additionally, collateral information was recorded in the database related to vanable factors such as type of gasket, composition of the gasket, percentage of gasket adhering in a flange surface, gasket surface area, and minutes elapsed lor removal RESULTS A database of some 20 factors was developed to record variables related to each of the eight fittings used in the six gasket re moval testing cvcles. These factors included, lor example, ope ol material (lull-lace gasket, ring gasket, partial-face gasket, or pack ing); comi'Hiwtion of the gasket when asbestos-containing (40 m 80% chrvsntile J; percentage of gasket adhering to a flange surface (0 to 100% t, condition of gasket (poor to excellent!; gasket sur face area m to 00 m:t, and minutes elapsed tor removal t 1 to 24 min). A database ot some five iactors was developed to record vari ables related to each of else eight valves used in the tw o packing removal testing cvcles These factors included, tor example, shaft outside diameter (0,56 to 1 625 inches I, packing housing outside diameter I 1.25 to 2.625 inches), packing depth |0.31 to 1.875 inches), and minutes elapsed for removal (5 to 26 mini 756 AIHA Journal (63) November/Dccembcr 2002 FIGURE <. Punching boil fiol*l In * gikt md tiling * blfp*en hmmr Not surprisinglv, a variety of gasket conditions were rncoun. tertd. ranging from tightlv adhered gaskets to loosely adhered gas kets. Of the 48 flanges, and thcrclbre 96 flange faces, that were cleaned bv either putts' knife, hand wire brushing, or power wire brushing, only 1 flange face did not require any removal of'resid ual gasket material This happened to be related to a lilting during an industrial fitting puttv knife test cycle. Tile other 95 flange faces had some material adhering to a flange face that required removal lit the method being studied. Twenty-one flange laces were esti mated to have 50% or more of' the face covered with residual requiring removal Personal samples during the testing of "industrial fittings'' ranged from 0.005 to 0.052 t/cc. The mean tit the personal sam ples of the five "industrial'' cycles was 0.026 fi/ic, Standard de viations ranged from 0 001 to 0.008 l/cc Table 1 shows die per sonal air sample results for the five test cycles in which industrial fittings were used Room air samples during the testing of industrial (minus ranged from 0.005 to 0.048 f/cc. The mean of the room air sam ples ut the five industrial cycles was 0,028 f/cc. Standard devia tions ranged from 0.00] to 0.006 f/cc. Table I shows the room atr sample results for the five test cycles in which industrial fittings were used. In test Cvclc I. "industrial flat blade scraping.'' seven of the eight fittings used contained an asbestos gasket. The average of the personal samples was 0.031 f/cc, and the av erage of the area samples was 0 026 f/cc In test cvclc 2, 'industrial hatid wire brushing." eight of the eight fittings used contained an asbesros gasket. The average of the personal samples was 0 006 f/cc. and the average of the area samples Was 0.008 f/cc. In test cycle 5. "industrial power wire brushing." five of the eight fittings used contained an asbestos gasket. The average of the personal samples was 0.022 l/cc, and the average of the area samples was 0.017 f. ec. In test cvclc 4. "industrial making gaskets with a ball pecn ham mer," eight of the eight fittings used had an asbestos gasket made. The average of the personal samples was 0.045 f/cc, and the av erage of the area samples was 0.040 l/cc. In test cycle 5, "indus trial srem packing removal and replacement," eight of the eight valves used contained asbestos packing, and all were replaced with asbestos stem packing. The average of the personal samples was 0.026 f/cc, and the average of the area samples was 0.025 f/cc Personal samples during the testing of "maritime fittings" ranged from 0.000 to 0 029 f/cc. The mean of the personal sam ples of the five maritime cvclcs was 0.013 t/cc. Standard devia tions ranged from 0.001 to 0.003 f/cc. Table I shows the personal air sample results for the five test cycles in which maritime fittings were used. Room air samples during the testing of maritime fittings ranged from 0.001 to 0.025 f/cc. The mean of the room air samples of the live maritime cycles was 0.0)2 f/cc. Standard deviations ranged from 0.001 to 0.003 f/cc Table I shows the room air sample results tor the five test cycles in which maritime fittings were used In test cvclc 6, "mantime flat blade scraping." right of the AIHA Journal (63) Novcother/December 2002 737 FIGURE 5. digging out th# *t*m packing ittor a hook did nol work. I_ eight fittings used contained an asbestos gasket. The average of the persntt.il samples " as 0.01" f/cc, .likt tile average of the area samples was 0.017 l/cc. In test cycle 7. -'maritime hand wire brushing," tour of the eight fittings used contained an asbestos gasket. The average of the personal samples was 0 002 f/cc. anil the average ol the area samples was 0.002 f/ce. In test cycle S, "maritime power wire brushing," eight of the eight linings used lomamed an asbestos gasket, The average of the personal samples vi as 0.009 f/ce, anil the average of the area samples vvas 0 011 f/ is. In test cvclc 9, "maritime making gaskets with a ball pcen hammer." eight of the eight fittings used had an asbestos gasket made Tile average of the personal samples was 0 026 f/ce. and the average of the area samples was 0.021 f/ce In test cvclc 10, "maoume stem packing remov al and replaiement." st\ of the eight valves used contained asbestos packing, and all is ere replaced with asbestos stem packing. The average of die personal samples was 0.009 f/cc. and the jverage of the area samples was 0.003 t'/ec. In summary, all 43 gaskets removed were elastomeric and tibrous, and 40 ot'them were determined to be asbestos-containingAll 16 of the gaskets made using a ball-pcen hammer w ere made from asbestos-containing sheet stock. All 16 packmes that were removed were impregnated and fibrous, and 14 of them were dc' termmed to be asbestos-containing. All 16 of the packings that were replaced were Irom NOS asbestos-containing packing. a 4 5 \ 3j DISCUSSION The air sampling results from both the the industrial test cycle* and the. live maritime test evelevwerc not significantlydifferc*1* TABLE I- Ten Test Cycle Sampling Results T*t Cycle Oeecription industrial *1--Flat blade scraping industrial *2--Hand wire brushing indusirial *3---Power wire brushing Induslnal *4--Making gaskets with a ball-poen hammer Industrial *5--Stem packing removal and roplacemenl Maritime #6--Flat blade scraping Martlime *7--Hand wire brushing Maritime #8--Power wire brushing Maritime 9--Making gaskets with a ball-peen hammer Maritime *10--Stem packing removaf and replacement Sample totals Sample Type personal room air persona! room air persona! room air personal room air personal room air personal room air personal room air personal room air personal room air personal room air personal room air No. Samples 2 8 2 8 2 8 2 8 2 8 2 8 2 8 2 8 2 e 2 8 20 80 Sampling Call Analysis Minimum (t/cc> Mean lcc) 0.035 0.034 0.007 0.010 0.023 0020 0.052 0.048 0.027 0.031 0.019 0.020 0 004 0.004 0010 0.014 0.029 0.025 0.010 0 011 0.026 0.008 0.017 0 040 0.023 0.017 0.002 0.011 0.021 0.008 Minimum ir/cc) 0.028 0 020 0.005 0 005 0.021 0.015 0 036 0.030 0.024 0.018 0.014 0.014 0.000 0.001 0.008 0.008 0.022 0.017 0.008 0.004 Standard Deviation 0,004 0.002 0 001 0.006 0.003 0.002 0.001 0.002 0.003 0.002 from each other. This was true tor the personal samples as well as lor the room air samples. Sample results tor the 10 test cycles .ire shown in Table ! The results of the 80 area samples and 20 personal samples indicate that no single sample ever exceeded the 8 hour TWA PEL ot 0.1 t/cc and thai only 1 persona! sample lat 0.052 f/cci ever exceeded halt' ot' this value. An tipper confidence limit of all the personal samples was calculated to he 0.069 1/cc Therefore, based on these findings, it is unlikely that exposures would ever approach the TfiL while these types of activities were performed, twtn when thes were performed tlrs. All samples were analyzed bs direct preparation in accordance with NIOSH 7400 Because it was assumed all detected Kbers ss'erc asbestos, u was not necessary to subsequently analyze these samples bv TF,M utilizing NIOSH 7402, Had definitive fiber identification been performed, it would have been incorrect to use a TEN! method other than NIOSH 7402. because methodologies such as El'A's AKKRA or Yam ate protocol, as well as ISO. have no relationship with the epidemiologicallv derived tihers per cubic centimeter exposure standards based on the PCM. It would fur rher be incorrect to compare the TEM unit ot "struaures/cubic centimeter" against the 0.1 l/cc allowable limits that arc to be determined bv PCM Intuitively, one would expect greater variation based on type of activity or asbestos content. For example, it would he reason able to expect the airborne fiber concentrations to be greater tor power "ire brushing sindustrial, 0.022 t'/ec; maritime, 0.009 1/ cci than they would be for flat blade scraping (industrial, 0,051 t/cc. maritime. 0 017 f/cc). One svoufc! also expect (tut an actis its that was literalh identical between tile industrial 1(1.045 f/cci and maritime (0.026 f/cei test cscles, n.llilcii that of making a gasket with a balbpcen hammer, scrutlc! viek.l more similar num bers results because it was the same hammer, same sheet material, similarly clean flange faces, and same people doing the work in a eleaiiroom. The numerical results would appear to show some differences But analysis of the database did not yield any significant correla tion between the air sample results and the multitude of recorded variables, including whether the material contained asbestos. One reason was that few fibers were detected on the filters, so a vari ation of a few libers counted made a significant difference in the reported value. Further, all fibers were being counted as asbestos whether they were or were not asbestos Also, the room air sample results were not significantly differ ent Inim the persona! air sample results for each of the test cycles. This was not surpoxing, because there was no ventilation in the room during testing, and over an 8 hour period it is reasonable m expect the personal samples would reflect die general air quality in a room with no ventilation. The results of this carefully controlled study arc consistent with other published studies m which the sampling and analytical meth ods are believed to have been properly followed tor comparison against the OSHA 8-hour TWA allowable exposure For example, the results (or dry scraping and power sanding reported be Cheng ei jJ calculate as 04)4 and 0 (I, f/cc on an 8-hour TWA. respec tively. The results lor production remov al of hard to-remove plate (sheet i gasketing reported bv Spence ct al. arc shown to range between nitnJetccUon arid 0.005 asbestos f/ml. oil an 8-hour TWA. Also, the results tor installation and removal ol sheet gaskets as reported bv Liukonen et al shoiv averages ranging Ironi 0.03 to 0.00 f/cc. All of these studies were conducted in actual work place situations w here there were other fiber influences. CONCLUSIONS This exposure assessment showed that the rate ot liber release for old and new elastomeric asbestos-Comaiding gaskers and impregnated asbestos packing materials are insignificant even when the materials are manipulated dry Although there is some quantified total fiber exposure during the activities typically per formed bv workers while using elastomeric asbestos-containing AIF1A Journal (63) Nmcmhcr/Occember 2002 739 gaskets am! impregnated asbestos packing materials, all sample re sults showed the airborne concentrations of fibers to be well below the current OSHA PEL ol'O.l f/cc as sampled user an 8-hour TU'A period. This is regardless of the activity being conducted and whether the activity was removal of an old elastomeric gasket or impregnated packing material or replacement with new elas 6 National Institute of Occupational Safety' and Health (NIOSH): AsbecTtis bv TEM. NIOSH Method 7402. In SJOSH Manual of An alytical Methods, 4ih cd. Cincinnati, Ohio; NIOSH. 1994 7 National Institute of Occupational Safety and Health (NIOSH); Asbestos and other fibers bv PCM, NIOSH Method 7400 In iYIOSH Manual of Analxtual Methods. 4th cd. Cincinnati, Ohio NIOSH. 1994 tomeric gasket or impregnated packing material. The studv methods controlled for potential interference that 8 Fowler, D.P.: Exposure to asbestos arising from bamhawmg gasket matenal Appt. Occup. Environ. Hyg. J5 404-408 (2000). could impact analvtieal confidence at the very low fiber concen trations related to gasket and packing activities. The studv meth ods also yield a high degree of confidence that the fiber concen 9 McKinncry, W.N., and R.W. Moore; Ev aluation of airborne asbestos fiber loch during rcmoxal and installation ot valve gaskets and pack ing Am Ind. Hyg. Assoc j 5J;53l-532 (1992) trations reported are those resulting from the respective gasket or packing removal or replacement activitv. Further, the results were obtained using tools and techniques as well as traditional worker methods with onh dry materials, drv removal, and dry replace ment techniques under conditions of no ventilation in a contained room. The results of this simulation, therefore, represent worst case conditions and are likclv higher than those that would be experienced in actual working conditions out of doors or in ven tilated spaces tl interfering fiber sources could be eliminated from 10. Millctte, J.IC, and M.P. Mount: A studs- determining asbestos fiber release dunng the removal of valve packing Appl Occup Euriron Hrp # 790-793 (1993). 1 I. "Asbestos Containing Materials in Schools--.Asbestos,Transmission Electron Microscopy," Code of Federal Regulations Title 4 0. Tan 763, Appendix A, Section 1, 1987. 12. Yomatc, G., S. AgarwaL and R, Gibbons: Methodology for she Mensurement of Airborne Asbestos b\ Electron Mtcroseopy (Draft Report. EPA contract no. 68-02-3266). Washington. D C.: Environmental Protection Agency, 1984 those settings. These findings arc usehil for exposure assessments and dose reconstructions related to historical activities and to current activ 13. International Organization for Standardization (ISO): Determi nation of Asbestos Fibres--Direct Transfer Transmission Electron Miavtcapy Method i ISO 10312). Geneva ISO. 1995 ities in which tin methods are used. 14 International Organization for Standardization (ISO): Determi nation of Asbestos Fibres--Indirect Transfer Transmission Electron Microscopy Method (ISO 13794) Geneva: ISO, 1999 ACKNOWLEDGMENTS 15 American Society for Testing and Materials (ASTM): Standard Test Method for Microvacuum Sampling and Indirect AnaJvsts of Thanks is extended to Central Illinois Light Co. for access to their decommissioned R.S Wallace powerhouse, which allowed the opportunity to obtain intact industrial fittings Ibr use in the Dust by Transmission Electron Mteroscopv tor Asbestos Structure Number Concentration f.ASTM D5755-9S. West Conshohocken. Pa ASTM, 1995 study. And also, thanks to the L .S X'ayy tor the intact maritime 16. "General Industrv Standards, Permissible Exposure Limns i PELS Code of Federal ReefuInnous Title 29. Pari 1910 1001(C)- 1994 fittings that came from cither the decommissioned destrovers C.S.S. Pas is, C.S.S Ricketts, or I' .S.S King, 17 American Conference of Governmental Industrial Hygienists (ACG1H): Threshold Ltnttr l)iinn for Chemical Substances and Plus- seal ,\neutt C" Ruifanicnl Expaittre htdtco Cincinnati. Ohio At GIH. REFERENCES 1998 18 R,5. Means Co.: Means Facilities Maintenance C" Repair Cm: Data 1 "Ltmnnumg Restrictions on Certain Asbestos-Containing Products," Kingston. Mass R.S Means Cu . 1994 Federal Register SR'5.W64 i 5 N<ncnihi*r. 199.G 19 Page, J.S.: Estimator!i Piping Man-Hour Manual Houston. Texas 2 "Technical Amendment m Response to Court Decision on Asbcvlas; Gulf Publishing Co., 1987 ", Federal Register .59;A32U8 2M lunc. 1994 i 20 Littleton. C.T., and R.A. Dickson. Industrial Ihptnn Nf" York. a Liukonen, L.R., K.R- Still, arid R,fL BcckctT: Astontit Exposure McGraw-Hill. 1951 t'rinu Castor Upcra twits Bremerton, Wash.: Industrial HvuK'nc 21 "Coimrucmm Indium Standards, OSHA Reference Method -- Mart Branch. Nasal Regional Medicj! Outer, 1978 datnrx." Code m' Federal Regulations Title 29. Djrt 1926 1101. Ap 4 Cheng, ICT,, and H.J, McDcrmotr: Kxpmurc to asbestos irom jv pendix A. 1994 bevios gaskets AppI Occup Environ H\n (V58S-59I ;|9y| i 22 Leidcl. N., K. Busch, and J. Lynch: (kcnpruumal Exposure Sampling A Spence, S.K., and P.S.J. Rocchi: Exposure to asbestos fibres during Strategy Manual (NIOSH contract CDC 99 74-75* Cincinnati. gasket removal A/nt Occup H\a 4fN5i83-58H <109f>, Ohio National Institute lor Occupational Safetv and Health. 19- 740 AIHA Journal (63) Nmci\\Ivr/Dccentticr 2002