Document zQ95yDbJbENw9yGgejVJVdMg

FILE NAME: Z< DATE: & DOC#: Z< DOCUMENT DESCRIPTION ^ZZ ZZZtZ Accepted Manuscript A Study of Airborne Chrysotile Concentrations Associated with Handling, Unpacking, and Repacking Boxes of Automobile Clutch Discs George C.T. Jiang, Amy K Madl, Kelsey 1. Ingmundson, Dana M. Mmbach, Kmt A. Fehling, Dennis J. Paustenbach, Brent L. Finley PH: DOl: Reference: S0273-2300(08)00039-1 10. 10 16/j.yrtph.2008.02.oo9 YRTPH 2124 To appear in: Regulatory Toxicology lwd Pharmacology Received Date: Revised Date: Accepted Date: 30 November 2007 19 February 2008 22 February 2008 Regulatory lOxicology and Phannacology tHffrJ.,l~ffflU1nH"'1JIt..rn..U.""#~,\-tJ td tr~lK.Ylinlt~~I""'Wal<op ....~"">r .. '" .;;;;" $cicoceOlred ~~~~I)$'" Please cite this article as: Jiang, G.C.T., Madl, A.K, Ingmundson, KJ., Murbach, D.M., Fehling, KA., Paustenbach, DJ., Finley, B.L., A Study of Airborne Chrysotile Concentrations Associated with Handling, Unpacking, ilnd Repacking Boxes of Automobile Clutch Discs, Regulatory Toxicology and Pharmacology (2008), doi: 10.10 16/ j.yrtph.2008.02.009 This is a PDF file of an unediled manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published ill its final fornI. Please note that during the production proce.',s errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. A Study of Airborne Chrysotile Concentl'ations Associated with Handling, Unpacking, and Repacking Boxes of Automobile Clutch Discs George CT Jiang 1, Amy K. Madl 1, Kelsey 1. IngmlUldson 1, Dana M. Murbach \ Kurt A. Fehling I, Dennis J. Paustenbach I, and Brent L. Finley I I ChemRisk, 25 Jessie Street, Suite 1800, San Francisco, CA 94105 * Corresponding Author: Brent L. Finley ChemRisk, Inc. 25 Jessie Street, Suite 1800 San Francisco, CA 94105 Phone: (415) 896-2400 Fax: (415) 896-2444 Email: bfinley({V.chernrisk.com Keywords: Asbestos, Automobile Clutches, Chrysotile, Exposure Assessment For Submission to: Regulatory Toxicology and Pharmacology Running Title: Clutch Study 0.001 flcc and 0.004 0.002 flcc when I or 2 boxes of clutches v.. ere handled, respectlvel\". Estimated 8-hr TWA asbestos exposures for a worker handling I or 2 boxes of clutches o\er a workday ranged from 0.002 to 0.006 f/cc. The 30-min PCM adjusted average airborne asbestos concentration for a worker continuously stacking unopened boxes of clutches \vas 0.212 == 0.014 f/cc; the 8-hr TWA was 0.013 flcc. Additionally, 30-min peM adjusted average airborne asbestos concentrations following cleanup and clothing handling were 0.002 0.001 flcc and 0.002 0.002 flcc, respectively, both resulting in estimated 8-hr TWA asbestos exposures of 0.0001 f/cc. The results of this study indicate that the handling, unpacking, and repackmg of clutches, and the subsequent cleanup and clothes handling by a \\orker withm a short-tenn penod or over the entire workday, result in exposures below the historical and current short-term and 8-hr occupational exposure limits for asbestos. 2 INTRODUCTION The purpose of an automotive manual clutch is to allow [or alternate connection and separation of the engine to the transmisSIOn shaft that drives the wheels. Similar to automotive brake pads and linings, clutch disc [aces frequently contain friction materials that come in contact with rotating metallic surfaces. Over time, the friction materials on the clutch will wear and the clutch disc must eventually be replaced or the clutch will begin to slip Manual clutches typically require repair or replacement every 50,000 to 100,000 miles. Figure 1 illustrates the location of a clutch and a cut-away schematic drawing of a clutch disc. ChrysotIle asbestos was a primary component of the friction material m manual automobile and truck clutch discs from the early 1900s to the 1980s. The chrysotile fibers, if present which comprised approximately 30-60% of the original clutch disc facing matenaL offered superior frictional characteristics such as good tensile strength, durability, flexibIlity, and heat resistance (Paustenbach et aI., 2004; Sheehy et aI., 1989; Skinner et aI., 1988). By the mid1980's, several acceptable substitutes for chrysotile asbestos were identified and the manufacture and use of asbestos-containing manual clutches was gradually discontinued in the United States (Paustenbach et aI., 2004: Paustenbach et aI., 2(03). During manual clutch installation and repair, asbestos fibers might become airborne if clutch wear debris IS present. Clutch wear debris is formed when the friction material d~grades due to the heat and pressure generated when the clutch surface is in contact with the flywheel and pressure plate. It has been kno\\TI for several decades that, similar to brake wear debris, the levels of chrysotile asbestos in clutch wear debris are very low, if any are detected (Boelter et al.. 2007; Kauppinen and Korhonen, 1987; Lynch, 1968; R J. Lee Group, 2004; Yeung et aI., 1999). Specifically, in 1968, Lynch reported no detectable fibers in clutch wear debris following normal dnving conditIOns (Lynch, 1968). Other reported measurements of asbestos in clutch wear debris are < 1% (Boelter et a1.. 2007) and non-detect to 0.4% (RJ. Lee Group, 2004). This is consistent with the fact that airborne concentrations of asbestos during clutch repair are also qUlte low. Numerous studies have shown that the time-weighted average (TWA) airborne asbestos levels during removal/installation of asbestos-contaimng manual clutches on automobiles and heavy equipment are consistently belo\', the current OSHA 8-hour permiSSIble exposure limit (PEL) of 0.1 flcc (Boelter et al , 2007, RJ. Lee Group, 2004~ Yeung et a1.. 1999). Workers who handle, unpack, and repack boxes of new clutches could also theoretically experience some degree of exposure to asbestos. Such workers would include the mechanics themselves, bystanders, "parts-pickers", and other staff at a distribution center or an auto parts store. Theoretically, residual asbestos fibers could be present inside a ne\\' clutch box, possibly as \vear during product shipping or as a result of airborne fibers "settling" into the open box III the manufacturing or packaging facility. These residual fibers could become airborne when the boxes are handled or the clutches are removed from the box and installed, or when clutches are "repacked" into the original box or another container. To date, there are no studies that descnbe airborne asbestos concentrations associated \vith clutch or box handling or cleanup activlties. We recently completed a study involving boxes of asbestos-containing brake pads and dlscs (Madl et al., 2007). In that study, we measured worker and bystander airborne asbestos levels during the unpacking and repacking of asbestos-containing brake pads and brake shoes. The results indicated that 1) airborne asbestos concentrations increased with the number of boxes unpacked and repacked, 2) handling brake pads resulted in higher asbestos concentrations than handling brake shoes, and 3) amphibole fibers were not detectable in bulk samples ofth8 brake pads and shoes. 4 In this analysis, we employ a similar research protocol to characterize potential \\'orker and bystander exposures to asbestos during the handling, unpacking, and repacking of asbestoscontaining clutch discs. Short-term and 8-hour TWA concentrations were measured and calculated under a variety of worker scenarios. In addition, we evaluated: (1) potential asbestos exposures associated with clean-up and clothes handling activities, and (2) size and morphology of airborne asbestos fibers. The resulting data are compared to historical and current OSHA short-term and long-term asbestos standards and cumulative chrysotile exposures experienced by other cohorts. These comparisons are used to determine whether and to what degree handling, packing, and re-packing asbestos-containing clutch discs might contribute to asbestos-related pulmonary diseases. METHODS The protocol [or the study was approved by Copemicus Group IRB (Research Tnangle Park, Ne), an accredited Institutional Review Board (lRB). Desertption ofBoxes ofClutch DISCS A total of 27 boxes of clutch discs were obtained from an automotive parts v"arehouse. The clutches were made prior to the mid-1980s for passenger vehicles and were therefore expected to contain chrysotile asbestos. The boxes had typically been in-stock and undisturbed for several years and were in good structural condition in the original packaging. The boxes were not taped together and did not appear to have been opened prior to the study. The bo:\.es were not opened prior to sampling to ensure that the results would be consistent v"ith a worker opening a new unused box of replacement clutches. Each box contained one clutch disc. The 5 brands on the boxes of the clutches were used to identifY the individual clutches (Table U). Figure 2A illustrates the worker with a stack of clutch boxes, and Figure 2B illustrates close-up photographs of representative brands of clutch dISCS and their respective boxes DescriptIOn afStudy Settzng The automobile repair shop where the study was conducted has been previously described in detail in Paustenbach et aI. (2006) (Paustenbach et aI., 20(6). The shop, \\hich IS located in Santa Rosa, CA, is a garage with an open floor plan with dimensions of approximately 101 ft wide by 48 ft deep with a IS-ft ceiling (Figure 3A). To prevent air sampling measurements from being confounded by other repair activities in the shop, no other automobile repair work was conducted on the testing days of this study. Additionally, the shop was not ventilated \vith heating or air conditioning. To simulate low ventilation conditions all entry and service doors were closed during the testing. Temperature and weather conditions were noted each day of the testmg. DeSCrIptIOn ofE.xposure ScenarIOS The difIerent tasks evaluated over the three days of study are summarized in Table I On January 20, 2007, discrete airborne asbestos measurements \vere obtained during the follov,ing tasks: 1) continuous repetItive stacking and handling 27 unopened boxes of clutches (onc event): 2) unpacking and repacking 1 box (4 events); 3) unpacking and repacking 1 box with overhead disc manipulation and dry cloth wipe (2 eyents) or spray clean wipe (2 eyents): 4) counter cleanup (one event). On January 21, 2007, the tasks were 1) unpackmg and repackmg 1 box (4 events), 2) unpacking and repacking 2 boxes with overhead manipulation (2 events), and 3) counter cleanup (one event). On January 27, 2007, the tasks were 1) unpacking and repacking 1 box (4 events), 2) unpacking and repacking 2 boxes wIth overhead manipulation (2 events), 3) counter cleanup (one event), and 4) clothes handling (one event). All box-handling work was performed by a single individual. The box and clutch handling activities were designed to be consistent with those described by career automotiYe mechanics and parts suppliers. The handling, unpacking and repacking of boxes of clutches was conducted at a 3.S ft high counter open to the automotiYe repair section of the shop (Figure 3A). The counter was w'iped thoroughly before each sampling event wIth a commercIal cleaner and a rag. Boxes of clutches were stored on the counter within reach of the worker. The handling activity consisted of opening the box, comparing the new replacement clutch to a demonstrative clutch, and then repacking the clutch in the original box. This entire process required approximately 1S-30 seconds. In some cases, the individual also cleaned the disc with a dry cloth or spray cleaner (30 seconds) and/or held the disc overhead (lO-IS seconds) before returning the clutch to the box. Each box was unpacked and repacked only once. The repetitIye box stacking task was conducted for the entire 30 minute period. Counter --cleanup" events occurred at the end of the day (for approximately 1 minute) and were performed using paper tovvels and \vet wipes. The clothes-handhng task (approximately 4S seconds in length) imohed shaking and folding 3 different pairs of overalls (a fresh pair was worn by the indiYldual durmg each day of testing) to simulate a person handling and laundering potentially "contaminated" work clothes. The overalls from the first 2 days were kept in a sealed bag until testing. CollectIOn and AnalYSIS ojAzrhorne Ashes/os Samples Airborne asbestos samples were collected in a manner consistent as previously described (Paustenbach et aI., 2006). Briefly, samples were collected using mixed cellulose ester (MCE) 7 filter membranes (25 mm, 0.45 !lm pore size, Zefon International, St. Petersbmg, FL, USA) using either portable SKC Universal PCXR (SKC-West Inc., Fullerton, CA. USA) or Gilian Gilair pumps (Sensidyne Inc., Clearwater, FL, USA) or Oawson 1300 high-volume sampling pumps (Ashtead Technology Rentals, Hayward, CA, USA). The sampling pumps \vere noted with a Bios(~ OryCal OCLite primary flo\\' calibrator (BlOS International Corporation, Butler, NJ, USA) before and after sample collection. Portable SKC or Gilair pumps were used to collect asbestos samples at 2liters per minute (LPM), whereas high-volume pumps were used to collect samples at air flow rates between 3 - 10 LPM. Collection of all airborne asbestos samples \vas consistent with NIOSH Methods 7400 and 7402 (NIOSH, 1994a; NIOSH, 1994c). Ounng each mdividual event, personal air samples were collected on the left and nght lapels of the worker. Specifically, worker lapel samples were collected in both IS-minute (n=...J., 2 consecutive samples on both the right and left lapel, 8 - 10 LPM respectively) and 60-minute (n=2, one sample on both the left and right lapel, 3 - 6 LPM respectively) tIme segments. In addition, during each event 30 minute area samples were collected at 1\,.,,0 bystander locations (5 feet from the main activity, 8 - 10 LPM), and a remote location (over 50 feet from the mam activity, 10 LPM) at breathing zone height (5 feet) (Figme 3A). To assess background conditions inside the facility prior to testing, three consecutive 30-minute samples were collected at the beginning of each day of testing at both bystander locations. Three consecutive 120minute ambient air samples \vere also collected each day of testing with a sampling rate of 10 LPM outside the south wall of the shop a\vay from automobile traffic. All e\'ent sampling was completed with the entry and service doors of the repair shop closed. After each box handling, clothes handling, or counter cleanup event, the doors of the shop were opened to air-out the workspace. A summary of the airborne asbestos sampling 8 events collected per exposure scenario is shown in Figure 3B. Fibers were counted according to the NIOSH Methods 7400 and 7402, which define iibers as being greater than 5 flm in length and 0.25 flm m diameter and havmg at least a 3' 1 aspect ratio (NIOSH, 1994a; NIOSH, 1994c). All airborne asbestos samples \\ ere sent to an American Industrial Hygiene AssociatIOn accredited laboratory (EMS Laboratories, Pasadena, CA) for analysis of asbestos by Phase Contrast Microscopy (PCM, NIOSH Method 7400) and Transmission Electron Microscopy (TEM, NIOSH Method 74(2) (NIOSH, 1994a: NIOSH, 1994c). Air samples were also analyzed according to the International Organization for Standardization (ISO) method for characterization of fi ber type, siLe, and morphology of fibers greater than 5 flm in length (ISO, 1995). Fzber Szze and Morphology Analyszs Because OSHA specifies peM analysis (with or without TEM analysIs) for the evaluation of occupational exposures to airborne asbestos, most \\'orkplace measurements of asbestos utIlize the NIOSH Method 7400. However, the NIOSH Method 7400 PCM analysis does not differentiate asbestos fibers from other structurally similar non-asbestos flbers. therefore OSHA has mdicated that TEM analysis (NIOSH Method 74(2) can be used to quantifY the ratIO of asbestos fibers to total fibers, which is then applied to the peM fiber concentration result (OSHA, 1994). To assess occupational exposure to asbestos, one can compare either the peM result or the peM adj usted result to the OSHA PEL. While the NIOSH methods 7400 and 7402 cannot be used to assess the fiber SIze (length and width) of any given fiber, the ISO Standard method is a refined techmque using TEM that permits characterization of both fiber si;:e and type, and it can differentiate between free fibers and fibers associated with a matrix (ISO, 1995). Using the ISO 10312 methodology, asbestos 9 fiber morphology in the personal air samples was quantIfied by categonLmg asbestos fibers greater than 5 !J,m in length as free fibers, free fiber bundles, fiber clusters, or matrix fibers (including matrix fibers, bundles, and dIspersed arrangements). In those instances where asbestos fibers were associated with a cluster or matrix, the dimensions of the cluster or matnx structure, as well as those of the individual fibers within the cluster or matrix, were recorded The ISO methodology was also used to assess the presence of amphibole fibers in the personal air samples. A number of studies have sho\\TI that fibers that are deposited in the pulmonary region of the lung are thinner than 0.7 !J,m and virtually all are thilmer than 1 flm (Harris and TimbrelL 1975; Strom and Vu, 1994; Sussman et aL 1991a, Sussman et aI., 1991 b; Yu et aL 1995). Therefore, for the purposes of this analysis, respirable fibers (free and bundles) were designated as those with width of O. 7 flm or less. Collectzon and AnalysIs of Bulk Asbestos ,"'ample.~' Filmgs of the clutch lining material from each box and the dust that accumulated on the counter dunng the box handlmg actIvities were collected for bulk sample analysis for asbestos in a plastic bag which \vas then sealed and sent for analysis. Both types of bulk material \\ere analyzed by EMS Laboratories (Pasadena, CA) using X-Ray Diffraction (XRO) accordmg to NIOSH Method 9000 (NIOSH, 1994d), and Polarized Light Microscopy (PLM) accordmg to NIOSH Method 9002 (NIOSH, 1994b). XRD analysis was used to determine the % composition (by \\'eight) of the bulk samples that were comprised of asbestos while the PLM analyses \\ ere used to assess the presence of chrysotile or amphibole asbestos fibers. The limit of detection (LOO) for PLM analySIS was 1%. 10 Air l!,xchange Measurements Using Tracer Gas Sulfur hexafluoride (SF6) was used as a tracer gas to estimate the air exchange rate within the garage as previously described by Paustenbach and coworkers (Paustenbach et al., 20(6). In summary, measurements of the gas were taken according 10 ASTM Method E741-00 (ASTM International,2001). A steady-state concentration of 1 ppm for SF6 (Sigma-Aldrich, St. Louis, MO) was targeted for the tracer gas analysis. Based on the estimated yolume of the repair shop, three Tedlar bags (Fisher Scientific, Hampton, NH) were filled with SF6 outside of the garage to prevent leakage into the shop. The bags were then released in the garage with all doors closed. Fans on either end of the garage were used to facilitate dispersion of the gas After steady-state was reached, SF6 measurements were taken in 30-sec intervals with a MIRAN SapphIRe-XL Analyzer (Thermo-Electron Corporation, Hayward, CA) for approximately 1 hr. The air exchange was calculated by the following equation: 0) The air exchange in the garage was calculated using the concentration decay (optional regression) test method by plotting the natural logarithm of SF6 concentration over time (ASTM International, 2001). Data and Statistical Analyses Descriptive statistics were calculated for both PCM and TEM measurements of airborne fiber concentrations. Analytical sensitivity limits were estimated based on the presumption that 1 fiber could be counted within 100 microscopic fields and the volume of air sampled (NIOSH. 1994a; NIOSH, 1994c) Results below the analytical sensiti,ity limit (LOD) were mputed using a value equal to one-half the sensitivity linut. PCM measurements ,vere adjusted for asbestos fiber content according to the method outlined in NIOSH Method 7402, whIch specifies multiplying 11 the ratio of asbestos fibers to total fibers obsen'ed in the TEM analysis by the peM fiber concentration (NIOSH, 1994c). The ratios of asbestos to total fibers (asbestos and non-asbestos fibers) were based on TEM fiber counts for the same filters from whIch the PCM fiber counts were obtained. The PCM measurements adjusted by the ratio of asbestos versus total fibers \\ ere referred to as 'PCM adjusted" (PCMadj) airborne asbestos concentrations in this study. In cases \vhere the PCM result was below the analytical sensitivity limit but asbestos fibers were detected in the corresponding TEM measurement, a value of one-half the peM analytical sensItinty limit was substituted and multiplied by the ratio of asbestos fibers:total fibers observed by TEM. In circumstances where peM measurements were above the sensitIvity limit (LOD), but a~bestos fibers were not detectable by TEM, a PCM-adjusted asbestos concentration was not calculated. All of the reported measurements for the varIOUS activities are the actual measured values and have not been adjusted [or contributIons from background or ambient sources. Thirty-minute TWA and 8-hr TWA airborne asbestos concentrations were calculated from the consecutiye IS-min samples collected on the right and left lapel o[ the worker using the following equations, respectively: I(C\ * 1,)/30 min (2) I(e, * fj)/480 min (3) where C, is the average airborne concentration (f/cc) for the left and right lapel collected [or each of the sampling segments and t, is the duration of the task. For the 8-hr TWA calculation, the mean of all the measured background values was assumed to be present for the remaining 7.5 hours of the workday. The IS-min concentrations \vere compared to the historical OSHA 15- min ceiling limit of 10 flcc (1972 - 1986) and the calculated 30-min TWA concentrations were compared to the current OSHA 30-min excursion limit of 1 flcc (1988 - present). Eight-hour 12 TWA airborne asbestos concentrations were compared to the current OSHA PEL of 0.1 flcc RESULTS Air exchange on the days of testing (measured with SF6 tracer gas) indicated rates of 0.4 air exchanges per hour on January 20,2007,2.0 air exchanges per hour on January 21, 2007, and 0.3 air exchanges per hour on January 27, 2007. These air exchange rates are similar to lhose reported previously for this building by Paustenbach et al. (2006) and are low compared to the rates expected in most auto repair facilities (ASHRAE, 1991; Paustenbach et al., 2(06). This is not surprising, given that no active ventilation system was present in the buildlllg and all doors and windows were kept closed during sampling. Asbestos Bulk Sample Analyses The chrysotile content of each clutch is summariLed in Table n. Bulk sample analysis (\'ia X-ray diffraction, XRD) indicated that all of the clutches contained asbestos and the mean chrysotile asbestos content was 33.7% 2.0, \vith a range of 20 - 52%. PLM analysis (LOO 1%) did not indicate the presence of amphibole asbestos fibers in any of the clutches. Bulk sample analysis (XRD) of dust which had accumulated on the countertop during the lIDpacking and repacking of boxes of clutches indicated an average chrysotile asbestos concentration of 6. 8% 2.2, and a range of 1 - 14% (Table Ill) Airborne Asbestos Sample Analyses Table IV presents the mean, minimum and maximum airborne PCM, TEM, and PCMadj 13 data for the dlfferent actlvities and sampling penods. Average sensitivity hmits for mrbome asbestos samples ranged between 0.0004 and 0.0042 flcc for PCM and 0.003 and 0.009 flcc for TEM (data not shown). As summarized in Table IV, the mean of the l't 15-minute PCMadj values for unpacking/repacking a smgle box were very similar in all handling scenarios: 0.051 flcc \\lth no manipulation, 0.050 flcc with dry wipe and overhead handling, 0.046 flcc 'with spray clean wipe and overhead handling. As is also summarized in Table IV, for each of these activities. the means of the 2nd 15-minute PCMadj values were far lower (means of 0.002,0.005 and 0 001 flcc, respectively) than the 1st 15-minute means. The mean of the 1st 15-minute asbestos concentrations assoclated with unpacking/repacking two boxes (0.196 flcc) was higher than the means measured with one box; however the concentrations measured during the 2nd IS-minutes v,:ere far lower (mean of 0.001 f/cc) and similar to the values measured "vith one box. The relatively higher personal measurements dunng the 1st minute sample (2 boxes) were not eVIdent at the bystander and remote locations (Table IV). Repetiti\ e stacking and handling of 27 unopened boxes generated the highest mean concentrations in this study (l st_ and 2nd 15-minute PCMadj means of 0.231 and 0.194 flcc respectively). Again, howe"er, airborne concentratlOns of asbestos above background were not present at the bystander or remote 10callons (Table IV) The trends observed in the 60 minute samples were generally consistent \\ ith those discussed above (Table IV). Cleanup and clothes handling activitIes did not generate significant concentrations of airborne asbestos (maximum PCMadj value of 0.006 flcc on personal lapel samples, no measurable asbestos fibers at remote or bystander locations). Samples collected at the bystander locations (5 feet away from the box activities) were less than 0.02 flcc regardless of activity, 14 while all of the samples collected at the remote location contained zero PCMadj values. Similarly, all background PCMadj samples collected between testing events and ambient measurements were calculated to be 0.000 flcc (Table IV). As can be seen in Table IV, every mdividual 15 minute sample was less than the historical OSHA short term lS-min ceIling limit of 10 flcc (1972 - 1986). As sho\\n in Figure 5, the calculated 30-minute TWAs for all activities were less than the current (l988-present) short term 30-minute OSHA standard of 1 f/cc. As shown in Figure 6, the calculated 8-hr TWAs for all activities were far below the current 8-hour OSHA PEL of 0.1 f/cc. Fzber Szze and Morphology Fiber SIze and morphology were assessed for personal worker samples collected during box handling, cleanup, and clothes handlmg activities. For the purposes of this analYSIS, the limit of detection of fiber length was 5 /-tm. When all the data are considered in aggregate (all activities combined) the results mdicate that 57% of the fibers counted were free fibers or bundles, 19% were fiber clusters, and 24% \vere associated with a matrix (Table V). Approximately one-third (29%) of the free fibers/bundles were of a respirable width (less than 0.7 /-tm). Very few (3%) of the fibers/bundles longer than 20 /-tm were less than 0.7 /-tm 10 width It should also be noted that 17% of the ""respirable fibers" (fibers of widths less than 0.7 /-tm) were actually bound in a matrix. Using a respirable particle definition of < 10 /-tm in diameter yielded similar values for the clusters and matrix-bound fibers. None of the personal air samples contained detectable amphibole fIbers 15 DISCUSSION The results of this study indicate a number of activity patterns and data trends that should permit an accurate evaluation of potential asbestos exposures associated with a variety of clutchhandling scenarios. Flfst, unpacking and repacking unused asbestos-containing manual clutches results in brief "peak" asbestos levels that rapidly return to concentrations at or near background levels. As a result, asbestos levels associated with unpacking/repacking one or two boxes did not exceed any of the historical or current short- or long-term occupational standards (Table [V and Figures 2 and 3). Cleaning the clutch face with a dry wipe or spray cleaner did not influence the airborne asbestos levels (Figure 4). Airborne concentrations at bystander locations (5 feet from the work activities) were even lower and often indistinguishable from background. Given the fact that garage mechanics rarely conducted more than one clutch change a week (Cohen and Van Orden, 2008; Kauppinen and Korhonen, 1987; Yeung et al., 1999), it can be concluded that clutch box handling did not result in exceedances of workplace standards for garage mechanics or co-workers at any point in time. Interestingly, the results of the "box-stacking" activity suggest that handling numerous unopened boxes in a short amount of time can result in higher asbestos levels than actually opening the boxes and handling the clutch. In this study, 27 unopened boxes were repetitively stackedlunstacked and otherwise moved about on the work counter throughout the first and second 15 minute periods (approximately 4 cycles of stacking/unstacking during each 15 minute period). The bystander (but not remote) concentrations were also elevated relative to all other activities. The box stacking activity constituted the first sampling event on the first day and therefore the results are not due to suspension of residual fibers from prevIOUS activities. Hence. the results indicate that repetitive handling of numerous unopened boxes (as might be c,)nducted 16 by a distribution warehouse parts picker, or occasionally by an auto parts dealer or counterman) could result in higher short-term exposures than might be experienced by a mechanic \\ho \\ould typically open one or two boxes a week at most. Nonetheless, the 15 minute samples \\ere all below the historical 15 minute STEL (l0 f/cc) (Table IV, Figure 4), the calculated 30-minute TWAs were all below the current OSHA 30 minute STEL of 1 flcc (Figure 5), and the calculated 8-hour TWAs (assuming background exposure levels for the remainder of the day) \\ere also below the current 8-hour PEL (0.1 f/cc) (Figure 6). Personal airborne samples collected during counter cleanup and clothes handling were all low and often non-detectable, suggesting that these activities would contribute little if any to the total asbestos exposure experienced by a mechanic, parts picker, or auto parts dealer. The data also suggest that "take home" exposures, as might be experienced by a person(s) laundering the clothes of the worker, \vould be minimal. It is interesting to note that the personal TEM results were higher than the personal peM results for all activities except cleanup and clothes handling, which indicates that non-asbestos fibers from the cleanup activities and clothing contributed to the peM values. This is consistent with the findings of Weir et al. in which airborne asbestos levels were measured during the agitatlon of a brake mechanic's clothing to detenmne the quantity offibers remaining on the clothing (Weir et aL 2001). The majority offlbers "ere not asbestos fibers, but other benign fiber types such as cotton fibers; the small amount that was asbestiform was composed of chrysotile fibers (Weir et al., 200 L). Similarly, analYSIS of the counter top bulk samples (collected at the end of each day) indicated a chrysotile content of 6.8% 2.2. This is much lower than the chrysotile content of the original clutch material (33 7% 2.0), suggesting the presence of non-asbestos material in the dust that accumulated on the counter (possibly from the box itself). It is also worth noting that the peM results of the 17 bystander and remote samples were consistently higher than TEM results, again indicating the presence of a significant number of non-asbestos fibers at these locations. The 10\\' airborne asbestos levels measured in this study are consistent WIth recenr studies of clutch handlmg and repair activities. Yeung et aI. (1999) reported no detectable airborne asbestos at a detection limit of 0.05 flcc (PCM) during a single clutch repair in an Australian passenger car service garage (Yeung et aI., 1999). RJ Lee (2004) measured airborne asbestos concentrations (PCM) during clutch servicing activities that included opening of the bell housing, removing the clutch plate and scraping debris from inside the housing (RJ. Lee Group, 2004). All 8-hour TWAs were below the current 8-hour OSHA PEL of 0.1 0 flcc (the highest reported concentration was 0.0363 f/cc) and in fact most samples did not contain any detectable asbestos fibers (RJ. Lee Group, 2004). Boelter et al (2007) reported 8-hr TWAs ranging from 0.007 to 0.013 flcc during clutch-specific repair from heavy equipment (Boelter et aI., 20(7). In many instances, the previous studies also involved brake servicing activities which may have influenced the airborne asbestos fiber concentratlOns. Hence, even if it \vas assumed that all of the asbestos measured in those studies was derived solely from clutches (i.e., brakes and gaskets made no contribution), the results \vould still clearly indicate that clutch repair does not result ll1 asbestos levels in excess of workplace standards. The airborne asbestos concentrations measured in this study are likely biased high for most settings. First, the data were collected under conditions of very little ventilation. Second, the boxes and the clutches used in this study were at least 30 years old and therefore the data are probably conservative for potential exposures that occurred when relativel) new clutch boxes were handled or opened. Third, while it is reasonable to expect that a mechanic or parts picker would open (and possibly repack) clutch boxes on a fairly consistent basis, it IS unlikely that an 18 auto parts counterman would actually repetitively shuffle and stack 27 clutch boxes on a COlmter in a 30-minute period. The same individual conducted all of the tasks in this analYSIS and therefore the influence of worker-to-worker variability is unknown. Given the fairly simplistic nature of the tasks conducted in this study (e.g., opening/repacking or shuffling clutch boxes), the influence of worker-to-worker variability should be minimal. Future studies e\ aluating more complex tasks (e.g., performing a complete clutch change) should address this potential variability factor. The clutches used in this study contained 33.3% 2.0 chrysotile asbestos by weight, as determined by X-ray diffraction. Although chrysotile fibers were used to manufacture asbestoscontaining automotive friction products such as brakes and manual clutches, it has been Imown for some time that certain chrysotile mines contained trace amounts oftremolite, a noncommercial amphibole fiber. Accordingly, it is theoretically possible that small amounts of tremolite may have been present in some asbestos-containing friction products at different points in time. However, the weight of evidence is largely negative in this respect. For example, Sheehy et al. (1989) found that fibers in 40 vehicles with asbestos-type brake shoes contained mostly chrysotile fibers, and that fibers in the wheel drwn bulk samples represented less than 1% of the brake dust, and were generally 60-100% chrysotile (Sheehy et al., 1989). Weir et al. demonstrated that an overwhelming majority of samples from dust collected from the brake drum where air was not used to blowout the drum contained non-fibrous matenal (cotton), and that most fibers were attached to phenolic residue deposits (Weir et aI., 2001). Weir et al further demonstrated that fibrous asbestos-containing material, determmed to be chrysotile by morphology, could be removed from brake pads by grinding or drilling processes, but they remained bound to the matrix of the underlying material (Weir and Meraz, 2001). Blake et al. 19 determined that air samples contained only chrysotile asbestos and an absence of other tvpes of asbestos following brake changes in 4 different vehicles (Blake et aL 2003). In a recent study, we found that 121 asbestos-containing brakes had no detectable amphIbole fibers (polanzed light microscopy analysis with a limit of detection of 1%) (Madl et aI., 2(07). Similarly, In the current study, we found that none of the 24 asbestos-containing clutches contained amphibole fibers (polarized light microscopy analysis with a limit of detection of 1%). It has been understood since the 1970' s that the disease-producing potential of an inhaled fiber is governed in part by the fiber dimension (Stanton and Wrench, 1972; Stanton et aI., 1972) Recent government expert panel evaluations have concluded that asbestos fibers < 5 Ilm in length (ATSDR) or up to 20 Ilm in length (EPA) probably do not contribute to disease (ATSDR, 2001; USEPA, 2003). Fiber ,\idths of> 0.7 Ilm are rarely found in the lung (Stanton et aL 1972; Sussman et aI., 1991a; Sussman et ai., 1991b; Timbrell, 1980; TimbrelL 1982) and for the purposes of this analYSIS 0.7 Ilm is assumed to represent the upper bound of a respirable width. Hence, fibers of> 5 Ilm and> 20 Ilm in length, both with respirable widths < 0.7 Ilm, are of particular interest in this study. The fiber size and morphology analyses of the an samples demonstrated that only 29% of the airborne free fibers > 5 ~lm in length were of a respirable width 0.7 urn). Very few (3%) of the free fibers > 20 Ilm in length were of a respirable width (Table V). It is worth noting that a significant fraction of the respirable OSHA fibers 0.7 urn width, >5 urn in length) measured in this study were present either in clusters (11 %) or were bound in a matrix (17%). The current understanding of lung deposition characterIstics of fibers is based primarily on free fibrous structures; the behavior of more complex fibrous stru.::tures. such as those attached to a matrix or resin, is less clear (Gross et ai., 1971; Harris and 1 imbrelL 1977; ISO, 1995; Morgan and Holmes, 1980; OSHA, 1994; Strom and Yu, 1994; Sussrnan et al.. 20 1991a; SussmanetaI., 1991b: Timbrel1, 1980: Timbrel1, 1982: Yu et al., 19(5). Presumably, at least some of these fibers would not be respirable due to a large aerodynamic diameter (oflhe cluster or matrix) and/or would not biologically active due to their encapsulation in a solid matrix. The PCM analytical methods typically used to monitor asbestos concentratIons ill the workplace cannot distinguish between free fibers vs. fiber clusters vs. matrix-bound fibers and, therefore, these results suggest that the PCMadj values reported in this paper are likely to overestimate actual respirable concentrations of OSHA fibers associated with different clutch handling activities. Since the late 1960's, numerous industrial hygiene studIes involving sen ice and repair of asbestos-containing brakes have consistently found that the airborne asbestos levels were below contemporaneous and current occupational standards (Agudo et aI., 2000: Goodman et a;., 2004. Hessel et aI., 2004; McDonald and McDonald, 1980; Paustenbach et aI., 2004; Paustenbach et aI., 2003; SPlrtas et aI., 1994; Spirtas et aI., 1985; Teschke et al., 1997; Teta et aI., 1983; Woitowitz and Rodelsperger, 1994; Wong, 2001). We recently developed estimates of cumulative asbestos exposures for brake mechanics based on industrial hygiene data and assumptions regarding the number of brake jobs a career mechanIC might perform (Fmle\ et aL 2(07). We reported that the median and upper-bound cumulative exposures for U.S. automobile and light truck brake mechanics who worked prior to the installation of dust-control technologies (i.e., before the mid-1970's) were 0.41 and 2.79 f/cc-years, respectively (Finley et aI., 2007) Similarly, estimates of lifetime cumulative asbestos exposuress associated \vith clutch box handling can be developed for a vanety of indi vidual work scenarios using the data presented in this paper (the product of the 8-hr TWA of a task and the number of years performing the task). For example, based on the 8-hr TWA estimate of 0.0016 flcc [or opening one clutch box (Figure 21 6), a 40-year career mechanic who performs one clutch change per week ,vouId expenence a cumulative chrysotile asbestos dose of 0.065 f/cc-years as a result of takmg the clutch out of the box (0.0016 flcc x 40 years). A counterman unpacking/repacking 10 boxes a week for 20 years would have a cumuIatlve exposure of 0.62 f/cc-years (S-hr TWA estimate of 0.0062 flce for unpackingirepacking 2 boxes x 5 x 20 years), while a parts picker stacking and shuffling 200 boxes per week for 5 years would have a cumulative exposure of 0.066 f/cc-years (8-hr TWA estimate of 0.0133 flcc for stacking boxes x 5 years). In all cases, background values were used for the "non-exposure" periods. These exposures, and generally any plausible exposures associated solely with clutch box handling, are smliIar to or less than the aforementIOned estimated exposures for mechanics conducting brake repair (Finley et aI., 2(07). Because it has been well-established that garage mechanics conducting brake repair are not an increased risk of developing asbestos-related diseases (Finley et aI., 2007), it can be inferred that the cumulatl\e asbestos doses associated with clutch box handling do not pose a health risk. Also, any estimated exposures from clutch box handling would be far below the cumulatIve "no-eITect" exposures that have been reported for chrysotile-exposed cohorts: 25-1,000 f/cc-years for lung cancer (Albin et aI., 1990; Berry and Nevvhouse, 1983; Bro\\n et aI., 1994; Hughes et al. 1987: Lacquet et aI., 1980; Liddell and Armstrong, 2002; McDonald et aI., 1983a; McDonald et al., 19S3b; McDonald et aI., 1984; McDonald et aI., 1993; Neuberger and Kundi, 1993: Pett) et aL 1985; Pierce et aI., 2007; Piolatto et ai., 1(90) and 15-500 flcc-years mesothelioma (Albm et al.. 1990; Lacquet et ai., 1980; McDonald et aI., 1984; Pierce et aI., 2007; Piolatto et aI., 1990). In short, our findings suggest that indi viduals opening, repacking, or otherV', ise handling cl utch boxes are not at an increased risk of asbestos-related disease. "Bystander" or "take-home" exposures would be even lower and would also pose no health risk. 22 In conclusion, we have assessed airborne asbestos concentrations associated with seyeral automotive clutch disc handling exposure scenarios not previously characteri;:ed in the literature A broad range of both typical and worst-case clutch box handling scenarios ,vas studied, In addition to evaluating potential exposure associated with handling work clothes or performing clean-up activities following these scenarios. While this study characterizes potential exposures associated with handling boxes of clutches, a scenario not previously assessed in the historical exposure studies of automobile mechanics, the results of this study should not be extrapolated beyond what was tested. In summary, the short-term and 8-hr TWA airborne asbestos concentrations measured and calculated for a mechanic or bystander unpacking and repacking boxes of asbestos-containing clutches were below the current OSHA excursion hmit and PEL for asbestos, as well as below all prevlOUS U.S occupational standards for asbestos. ACKNOWLEDGEMENTS This research was supported by funding from Borg-Wamer Corporation, \\ho have been involved in litigation related to the possible exposure of clutch mechanics and handlers, and theIr family members, to asbestos. Some of the authors have served as expert witnesses in litigatIon regarding the potential asbestos health hazards to mechanics and friction product handlers historically involved in automobile-related work. 23 LIST OF TABLES AND FIGURES Table I. Summary of clutch handling and associated actIvities performed throughout the simulation study. Table n. Chrysotile content of the 24 clutch linings used in the simulatIOn study Table Ill. Chrysotile content of the counter dust from the simulation study. Table IV. Summary of airborne asbestos concentrations (f/cc) during different handling scenarIOS. Table V. Size and morphology distribution of fibers detected in personal \-vorker samples collected during various clutch handling and associated activities. Figure 1. Schematic drawing of a clutch and its location. Figure 2. (A) Photograph of the stack of clutch boxes. (B) A close-up view of a clutch and its clutch box. Figure 3. (A) Diagram of automotive repaIr shop and locations of area sampling stations (B) Schematic of sampling scheme for airborne asbestos sampling collected during each clutch handling associated event. Figure 4. PCM-adjusted airborne asbestos concentrations for the worker during different clutch handling associated scenarios. Figure 5. 30-min TWA airborne asbestos concentrations for the worker dUling different clutch handling associated scenarios. Figure 6. Estimated 8-hr TWA airborne asbestos concentrations for the worker during different clutch handling scenarios. 24 REFERENCES Agudo, A., et aI., 2000. OccupatIOn and risk of malignant pleural mesothelioma' A casecontrol study in Spain. Am J Ind Med. 37, 157-168. Albin, M., et al., 1990. Mortality and cancer morbidity in cohorts of asbestos cement workers and referents. Br J Ind Med. 47,602-10. ASHRAE, Heating, Ventilation, and Air-conditioning Applications. American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., Inch-Pound EditIOn. Atlanta, GA, 1991. ASTM Intemational, Standard test method for determining air change m a single zone by means of a tracer gas dilutIOn. American Society for Testing and Materials, West Conshohocken, PA, 2001. ATSDR, Toxicological profile for asbestos. U.S. Department of Health and Human Services (DHHS), Public Health Service, Agency for Toxic Substances and Disease Registry (ATSDR), Atlanta, GA, 2001. Berry, G., Newhouse, M. 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Some aetiologic consideratIOns o[ fiber carcinogenesis Laboratory of Pathology, National Cancer Institute; Presented at: Biological Effects Of Asbestos conference, Lyon, France, Oct. 2-5 1972, Paper 43A Strom, K. A, Yu, C. P., 1994. Mathematical modeling of silicon-carbide whIsker deposition in the lung-comparison between rats and humans. Aerosol Sci Technol. 24, 193-209. Sussman, R, et ai., 1991a. Asbestos fiber deposition in a human tracheobronchial cast. I Experimental. Inhal Toxicol. 3, 145-160. Sussman, R 0., et aI., 1991b. Asbestos fiber deposition in a human trancheobronchlal cast. 11. Empirical model. Inhal Toxicoi. 3, 161-179. Teschke, K., et al., 1997. Mesothelioma surveillance to locate sources o[ exposure to asbestos. Can J Public Health 88, 163-8. Teta, M. J, et aI., 1983. Mesothelioma in Connecticut, 1957-1977, Occupational and geographic associations. J Occup Med. 25, 749-756. Timbrell, V., Measurement of fibers III human lung tissue. In: Wagner, 1. C , (Ed), Biological effects of mineral fibers. International Agency [or Research on Cancer, Lyon, France, 1980, pp. 113. Timbrell, V., 1982. Deposition and retention o[ fibers in the human lung. Ann Occup Hyg. 26,347. USEPA, Final Draft: Technical support document [or a protocol to assess asbestosrelated risk. US Environmental Protection Agency. Prepared for the Office of Solid Waste and Emergency Response, Washington D.C., 2003. 28 Weir, F. W., Meraz, L. B., 2001. Morphological characteristics of asbestos fibers released during grinding and drilling of friction products. Appl Occup Emiron Hyg. 16, 1147-9. Weir, F. W., et aI., 2001. Characterization of vehicular brake service personnel exposure to airborne asbestos and particulate. Appl Occup Em-iron Hyg. 16, 1139-46. Woitowitz, H. 1., Rodelsperger, K., 1994. Mesothelioma among car mechanics'? Ann Occup Hyg. 38,635-638. Wong, 0., 2001. Malignant mesothelioma and asbestos exposure among auto mechanics: appraisal of scientific evidence. Regul Tox.icol Pharmacol. 34, 170-7. Yeung, P., et aI., 1999. An Australian study to evaluate \vorker ex.posure to chrysotilc in the automotive service industry. Appl Occup Environ Hyg. 14,448-57. Vu, C. P., et al., 1995. Deposition of refractory ceramic fibers (RCF) from the rat lung- development of a model. Environ Res. G5, 243-253. 29 Jlang et al. A Study of Airborne Chrysotile Concentrations Associated with Handling, Unpacking, and Repacklng Boxes of Automobile Clutch DIscs Table I Summary of clutch handling and associated activities performed throughout the simulation study Activities Day 1 Stack boxes 1 U/R 1 box 4 U/R 1 box, DW, OH 2 U/R 1 box, SC, OH 2 U/R 2 boxes, OH Clean counter 1 Clothes handling U/R - UnpacklRepack Day 2 4 Day 3 4 2 2 1 DW- Dry wipe Activity replicates 1 12 2 2 4 3 se - Spray cleaner # personal worker samples 4 48 8 8 16 12 4 OH - Handle overhead Jiang et al. A Study of Airborne Chrysotlle Concentrations Associated with Handling, Unpacking, and RepacklnG Boxes of Automobile Clutch DIscs Table II Chrysotile content of the 24 clutch linings used In the simulation study, Brand Brand 1 Brand 2 Brand 3 Brand 4 Brand 5 Brand 6 Brand 7 Brand 8 Brand 9 Brand 10 Brand 11 Brand 12 Brand 13 Brand 14 Brand 15 Brand 16 Brand 17 Brand 18 Brand 19 Brand 20 Brand 21 Brand 22 Brand 23 Brand 24 XRD Result (Chrysotile %) 27 29 39 52 48 48 23 43 44 39 26 35 43 28 33 27 33 20 25 21 20 47 28 31 PLM Result (Amphibole %) NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO Note' NO - non-<ietectable, XRO - X-ray diffraction, PLM - Polarized light microscopy, Non-<ietectable samples entered as one-half the limit of detection or sensItivity limit limit of detection =1% Jlang et al A Study of Airborne Chrysotlle Concentrations Associated with Handling, Unpacking, and Repacking Boxes of Automobile Clutch DIscs Table III Chrysotlle content of the counter dust from the simulation study Sample ID Sample Jl.KU KeSUIt (Chrysotile %) I-'LIVI Kesult (Amphibole %) All boxes Counter Dust 2 ND Counter 012007 Counter Dust 5 ND Counter 012107-A Counter Dust 5 ND Counter 0121 07-8 Counter Dust 1 ND Counter 012707-A Counter Dust 14 ND Counter 012707-8 Counter Dust 9 ND Note: ND - non-detectable, XRD - X-ray diffraction, PLM - Polanzed light mlcroscopy, Non- detectable samples entered as one-half the limit of detection or sensitivity limit LOD =1% Jlang et al A Study of Airborne Chrysotlle Concentrations Associated with Handling, Unpacking, and Repacking Boxes of Automobile Clutch OISC~ Table IV. Summary of airborne asbestos concentrations (f/cc) dUring different handling scenarios PCM TEM PCMadj Location Task Replicates N Mean Min Max %NO N Mean Min Max %NO N Mean Min Max Worker One box 12 24 0057 0.006 0138 0 24 0132 0010 0400 0 24 0051 0004 0138 (1st 15 mln) One box, OW, OH 2 4 0058 0.035 0.120 0 4 0.115 0.060 0200 0 4 0050 0.027 0.109 One box, SC, OH 2 4 0.055 0.034 0073 0 4 0.078 0060 0.100 0 4 0046 0034 0063 Two boxes 4 80209 0.110 0370 0 80413 0100 0700 0 80.196 0102 0366 Stacking boxes Cleanup _ _ _ ... glothe~hC!~Iirl..___ Worker One box 1 2 3 6 2 12 --"- ----24 - 0.294 0.012 0110 0.011--- 0278 0006 0090 0 005 0.310 0 ! 2 0 600 0.500 i 0021 0, 6 0006 0004 i, 0130 0 2 0006 0004 O.019--~-o-1--~-24---00-66---0063 0 700 0 0008 50 0007 50 --0-02-0--71- 2 0231 0.217 0.245 6 0002 0.000 0006 2 0,003 0.000 0005 24 0-502----0.00-0---0-.0-0-8--- (2nd 15 mln) One box, OW, OH 2 4 0014 0.008 0019 0 '4 0010 0005 0020 0 4 0005 0.003 0,008 One box, SC, OH 2 4 0007 0005 0010 0 4 0011 0 004 0030 75 4 0001 0.000 0,005 Two boxes 4 8 013 0 008 0 024 0 8 0 005 0 004 0 010 75 8 0.001 0 000 007 Stacking boxes 1 20.230 0207 0253 0 20450 0400 0500 0 20194 0180 0207 Cleanup 3 6 0010 0.004 0018 0 I 6 0005 0.004 0.007 67 6 0002 0.000 0006 Worker (60 min) Clothes handling One box One box, OW, OH .. 244 . 2 0047 0.039 0054 0, 2 0.004 0.004 0005 100 I 2 __0_0_00._._._ 000o_.__ .. 0._000 ~ -~4- ~.~~~" ~ ~~; ~ ~:~ ~ rr~4--'- ~ ~;;~~~~ ~ ~;~ ~ 1 ~ ~~~ ~ ~~~ ~ ~;: One box, SC, OH 2 Two boxes 4 _______ Sta~l<ing_~~_. Bystander One box 12 4 0017 8 0.061 0.007 0027 0026 0097 0 I4 0 I8 0 017 0121 224 6':'M'-~~--~-~~-:---~-~-;;----~--- -;l-4--~~g~ ;i 0006 0.050 00.030 30 122 ~ I 48 00001534 ~.~~~.-- ~ ~%~.~~ '2~-' ~ ~~~ 00 . 000224 00'092 21 ~:~~~ ..-~~~~-- : : 1:8 ~ ~~! ~ ~~~ ~ ~~; ~ ~:~~~ ~ ~~~ ~ ~~~ ;3~8 One box, OW, OH 2 One box, SC, OH 2 Two boxes 4 8 0009 0.002 0019 0 8 0007 0002 0.020 ~.~~~ ~.~~~ ~ ~~; 0004 0000 0019 Stacking boxes 1 2 0030 0.027 0032 0 2 0007 0 004 0009 0 I 2 0010 0 003 0016 Cleanup 3 6 0006 0001 0015 0 6 0.002 0002 0.004 83 i 6 0000 0000 0000 ____ ..__Clothe~.b'c!!l<l~Ir1L __. _____ . 2 0010 0006 0013 0 Remote area One box 12 1cc2=----0=-.0=-=08 "'-0-0-03---0022- 0 2 0004 0.004 12--cio64----0-004 -00.0.040071090 HrI 212-0-00-0 0~ 0.000 0000 0000 ---'0003- One box, OW, OH 2 2 0005 0001 0008 0 2 0004 0.004 0.004 100 I 2 0000 0.000 0000 One box, SC, OH 2 2 0005 0003 0007 0 2 0.004 0.004 0004 100 2 0000 0.000 0000 Two boxes 4 4 0003 0001 0006 0 4 0004 0.004 0007 100 4 0000 0000 0000 Stacking boxes 1 1 0008 0008 0008 0 1 0004 0.004 0004 100 1 0000 0000 0000 Background Cleanup Clothes _handling o [ 3 3 0006 0004 0010 0 13 0004 0004 0004 100 3 0000 0000 0000 1 1 0009 0009 0009 0004 0004 0004 100 0000 0000 0.000 3 9 o 007 0 002 0 014 0 9 0 004 0 004 0 004 100, 9 0 000 0 000 0 000 Ambient 3 9 0001 0000 0.001 0 9 0 004 0 004 0007 89 I 9 0,000 0 000 0000 Jlang et al. A Study of Airborne Chrysotlle Concentrations Table V Size and morphology distnbutlon of flbers detected In personal worker samples collected during various clutch handling and associated activities Fiber Structure Classification Total Flbers Free Flber/Bundle Flber Clusters Matrix Disperse N 1424 816 267 341 Total Fibers (%) -- 57% 19% 24% Percent Fibers (%) Classified as Fiber or Particle with Dimensions of Respirable Fiber Respirable Particle* <0.7 fJ-m width >5 fJ-m length >20 fJ-m length -_. --- 29% 3% 11% 1% <3fJ-m width >5 fJ.m length --. >20 fJ-m length _.- 41% 6% 15% 2% <10 fJ-m width >5 fJ-m length >20 fJ-m length -- _.- --- --- 15% 2% 17% 2% 21% 3% 21% 3% Figure 1 Transmission , 0 t Pressur'e Plate t Flywheel 1 Engine Figure 2A Figure 2B Figure 3A Ef't(:.iQ$ea '~iI\tartln.g ,~re4 , I I I 1.<.il.l.- - - - - . ':' 11- - - I ~ I :~~'''~ f ... I ~, " I " r _ . . .\ l"',,~~,j i 1,'------1.... ....~--------~~." - - - - ,I linE 9.1 n I I I I ~---------, I t I I Figure 38 Worker --/ , I I I ~: Bystander I 15-min 111...--_1_5-f11_i_n----' [ 60-min "--------------~--~ ----- 30-min Remote 30-min Figure 4 rL2 I , . . J.tJ~ " j ... ~: ," 1_' :>1 .1, .~: , , --I , 11 ! :- :'" l :,'!- i , r o ' ; " ' Of, Figure 5 1.20 _ ... -~ .. -- - - - - - - - -<_.-. - -. - - - - - - - - - OSHA. 30~- rr-in- - - - - E~cmsion Li-rdt-(19-8B--p-re-s-en-t). G.DU 0)]26 One b0>: (N;;:;;'12) 0.027 !] .023 One bo'~;', DVV, OH (1\1=2) On'\? Box, se, OH in::':'?1 " .~ 0099 l/oJ':O bo >: :i;"3 (N:::-4) 0.212 lJ C1CQ 1::'1E'-,;mu F (i\F3) O.oJ2 !~:Iothes h3nrtng (N",-'1,) Figure 6 'l',' 1~~' 1 - i- ....r;.J u -...'if 1 .... I.; 1~) 0 -c:I- , I '\lJ I:: I);::: U c 0 I !lU ! <I I.I~: ~ .0 I u~ .. I! 0 t:i [:! IJ..~ I~ I Q;l .g I oc( I,?' (U j'! ~ ! 1 Cl e I ~ i I l- ..:( ni', < Er. JIG it ,'.., \ -.... , I " >1,'":' i " ~T . ' , r I ;.. 10 , ,.I " , .j - .- ,, ,t '.1.1, " " i : I [I}' , '.1 -, - [~\.~ -1' ! ,~ '. '~. -.~ ~' ' " ..J! ! I I I J '~tf~