Document Ed14v27ojKvoVEj3LX3E4DMBN

ft .. )4gpilecrOriku|Mitioi3l and Environmental Hygiene *' Afelame IA;448-457,1999 MiMllViXto $1200 + .00 EXHIBIT Aw Australian Study to Evaluate Worker Exposure to Chrysotile in the Automotive Service Industry Paul. Yeung, Kim Patience, Linda Apthorpe, and Deborah Witlcocks Worksafe Australia, Sydney, Australia t' \ i - A.study was conducted in Sydney, Australia, in 1996 to 'investigate the current exposure levels, control technologies, and work practices in five service garages (four car and one bus), three brake bonding workshops, and one gasket pro cessing workshop. This study formed part ofthe assessment of chrysotile as a priority existing chemical under the Aus tralian National Industrial Chemicals Notification and As sessment Scheme. A total of 68 (11 personal and 57 area) air samples-were collected, in accordance with the Australian Standard membrane filter method. Fiber concentrations were determined by the traditional phase contrast micro 'Bjscopy (PCM) method and Id selected samples were analyzed '"|ie more powerful transmission electron microscopy 'Chrysotile exposure ofcar mechanics measured by PGM was typically below the reportable detection limit of OJOS f/mL, irrespective ofwhether disc brake, drum brake, oi*'clutch was bring serviced. These low levels can be at tributed to the wet cleaning or aerosol spray methods used ip recent years to replace the traditional compressed air jet cleaniag.Tn the three brake shoe refining workshops, task- specific exposure reached up to 0.16 f/mL in the processes of cutting and radios grinding. TEM results were gener- nlly higher, doe to its higher resolution power. The median diameter on samples taken from the service garages (pas senger cars), as determined TEM, was 05-1.0 pm; and - wasbetween (12-05 pm'loflEe brake bonding and gasket processing workshops, while that for the bus service depot s'iOJMfc? pm. Most of the respirable-fibers (84%, mainly felkfetitej-from the bus service depot were below 0.2 pm |ft^ittteter:'#i>Ich is the resolution limit of PCM. In the .bHi^yindlng and gasket cutting workshops, 34 percent aii44'pefc*'nt'of the chrysotile fibers were below 0.2 ftm in fitlfiiiiete ' Keywords Automotive Service, Brake Bonding, Brake Service, Vfe' Chrysotile, Gasket Processing, Service Garage In Australia, industrial chemicals are assessed for safety and registered under the National Industrial Chemicals Notification arid Assessment Scheme. The use of chrysotile is being re viewed under thepriority existingchemical assessmentprogram. The review Is a risk assessment process based on the inherent hazard of the material and its* likely impact on occupational health and safety, the environment, and public health and safety. The assessment process will also make recommendations on measures tocontrol these risks, investigate the present use ofsafe substitutes for chrysotile, and address the feasibility of phasing out the nse of chrysotile in Australia. Chrysotile is still used in the manufacture of motor vehicle brake and clutch materials in Australia, although increasingly other materials (for example, metal oxides, synthetic mineral and organic fibers) have been substituted for asbestos in the fabrication of friction materials. Friction materials commonly found in brake and clutch systems contain about 40-60 per cent (drum brakes and clutches) and 20 percent (disc brakes) chrysotile asbestos (together with phenolic-type resins as binder and various other additives to improve performance). Amosite. crocidolite, or other amphibole asbestos varieties are not used because they are too harsh and tend to score the brake drums or discs.*** Many of the chrysotile fibers originally present in the brake and dutch materials can undergo thermal degradation to forsterite or to a non-fibrotis silicate phase, due to the high temper ature encountered in use.*2* Free chrysotile fibers can also be released because of abrasion and other shear processes. Un like cheysotile, the health effects of exposure to fotsterite, ahd to the transition series fibers (chrysotile/forsterite) with altered crystalline structures, are not well documented. The debris re maining in (he brake and clutch assemblies and encountered in normal automotive service contains a combination of these fibers. Chrysotile fibers usually constitute less than 1 percent in weight of the debris.*1* Asbestos-related diseases have attracted considerable atten tion in the Australian community. A study of (he 16-year data from the Australian Mesothelioma Surveillance Program and 1 ym Reg me.s (bra 199 gar; den serif X raw Aus in vr for I live! Earl char serv to d: porn C rouii Iftli. and < prao live of w aulot durii gask- BRA R depo into movt brake ing \ most ing. f clean orch the-a The clean fibert W disc j opera HWBUI0007674 ty and cation lg regram, terent (tonal afcty. ns on fsafe asing l*> tngly neral n the tonly perakes) inder >site, used ns or >rake rstetpero be Unand ered s reered tese it in tendata and AUTOMOTIVE SERVICE WORKER CHRYSOTILE EXPOSURE . ' ' .' Register between 1979-1995 has indicated that the number of in an oven at a trmtperature of 200^300^6* J$ mesothelioma cases in Australia had increased in car mechanics and leveling of the new brake lining Sii^ce (cpthntdni^vbalie^isii. (brake work) from 7 cases in 1979-1985, to 16 cases in 1986- "radius grinding") is routinely required and is the mbsKliitely -; 1990, and to 24 cases in 199 l-1995.p,4> Althougha link between source of fiber generation. Cutting of new linings is tosoSome^ garage work and cancer has not as yet been established by epi times performed. demiological study, the recently reported cases ofmesothelioma strike a warning note. Much is known about the risk of occupational exposure to raw asbestos fibers in miming, milling, and manufacturing in Australia and elsewhere. The picture is less clear in Australia in work with asbestos-containing materials where the potential for fiber escape and associated airborne contamination is rela tively low, as, forexample, in motor vehicle repair and servicing. Earlier overseas studies ofairborne asbestos exposure to car me chanics showed significant exposure to chrysotile during brake servicing, especially brake assembly cfeaning.(l,6-w> However, to date, no similar exposure studies in Australia have been re ported in literature. Car mechanics are potentially exposed toasbestos dustduring GASKET PROCESSING. -. Asbestos-free gaskets are widely used in (he autohioUve in dustry arid for other purposes. However, asbestos gaskets are- still found in older models of passenger.cars.ait(l'heavy. vehi- cles. although nowadays they are more commonly used-inhigh-' temperature and high-pressure applications (foe example,In.oil refineries and chemical plants). In asbestos gasket productionoperations, articles are cut off from compressed asbestos fiber sheets by hand-held electric saws, and are then cut to. the de sired shapes by a powered stamping machine. Process workers, are potentially exposed to asbestos dust during the cutting and powered stamping process. routinebrake, clutch, and gasket maintenanceservice andrepair, if the debris inside the. brake and clutch assemblies is removed and disposed of using appropriate control equipment and work practices, the exposure can be minimized. The principal objec tive of this study was to determini the exposure to chrysotile of workers in the automotive service industry, particularly of automotive mechanics who may use various control techniques during maintenance and replacement of brakes, clutches, and gaskets. METHODS AND MATERIALS Nine typical establishments in die Sydney metropolitan area, including five service garages (fourfor passenger and light com mercial vehicles, one for buses and coaches), three brake bond ing workshops,and one gasketprocessing workshopparticipated in this study.The three brake bonding workshops and one | processing workshop were the only workshops is the indite*^*/ that still processed asbestos-containing products aod.were lo- BRAKE AND CLUTCH SERVICE OPERATIONS rated in the Sydney metropolitan area. . The study methodology involved air monitoring to estimate Repair facilities ranging from small service stations to bus exposure to chrysotile at work when chrysolite-containing fric depots follow similar service procedures. The vehicle is driven tion materials were worked on, in relation to the type ofcontrol: into a repair stall or bay, sometimes elevated,.wheels are re measures used, and sizing of airborne fibers by transmission moved, and the brakes or clutch are inspected. Traditionally, election, microscopy (TEM). In this study, the dust control tech brake dust was often cleaned from brake assemblies by blow niques were also assessed, and the work practices and the.'nse ing with compressed air. At the time of this study, however, ofpersonal protective equipment were evaluated by the use ofa most brake servicing facilities we observed used wet/dry wip standardized questionnaire. ing; squirt bottle wash-off, or aerosol'can organic cleaner. After cleaning, patjsasi replaced or repaired as needed, and the brake or clutch systemTs reassembled and adjusted. Dust arising from the work was obviously a possible source of asbestos exposure. The debris accumulated in titd brake housing,,and when it was cleaned outby oae ofthe above methods, could liberate asbestos fibers into the ambient air. With the introduction of bonded linings and factory-made disc pads in recent years, the need fordrilling, facing, orgrinding operations during installation has decreased significantly. Monitoring of Airborne Asbestos Fibers j Thsk-specific personal and area tor samples were collected at a flowrate of2 liters per minute on 2S-mm~diamster0.8 fi$ pore size Millipore mixed cellulose ester membrane filters honied in anti-static cowls, in accordance with the Australian standard membrane filter method/11* Area samples were taken at fixed, locations in the vicinity of the work tasks, and between one and two meters above floor leveL Single sample-durations Were selected not to exceed two hours, such that only a maximum of BRAKE BONDING OPERATIONS 240 titers of tor would be collected. This approach has resulted in a practical detection limit of around 0.05 taL-(or lb fibers/ Worn drum brake shoes collected from brake service stations 100 graticule areas) by phase contrast microscopy (PCM). are re-processed in specialized brake bonding establishments. Filter sections werecleared by acetone-triacetin and the fibers The metal shoes are stripped of the worn asbestos linings, then were sized and counter}, under a phase contrast optical;m ) cleaned, glued to precut replacement linings, and finally cured scope at 400-450x magnification, fibers-with an aspeerti..-^--^ HWBUI0007675 ... 450 P. YEUNG ETAL. 6 exceeding 3, with length greater than 5 /nm, and diameter under A pith, were.counted to a minimum 'of 100 fibers in 20 fields rarely need to undertake activities such as cutting, grinding, and drilling which may release fibers to the ambient air. .r 100 random fields. The limit of resolution of PCM is about Waste friction materials generated in these workshops (e.g., 0.2 jim. . > worn brake discs in garages, asbestos-containing debris in brake In.addition to PCM analysis, 16 samples in half filters were bonding workshops) were kept in special closed bins and dis selccipd forTEM analysis on a Phillips CM12 at 8800x magrrifi- posed of by licensed waste contractors. Only some asbestos- cation>These 16 samples included all personal samples and some containing products were labelled with the appropriate hazard area samples with relatively high PCM fiber readings. TEM warning and safe handling instructions. However, none of these analysis was perfonned to identify asbestos fibers too small to products was provided with MSDS. be. detected by PCM. Fibrous minerals were identified by se lected area electron diffraction (SAED) and energy-dispersive X-ray analysis CBDAX), and sized by length and diameter. The grid openings used in TEM were sized by optical microscopy so that the TEM results could be reported in fibers per equiva lent .Waltoa Beckett graticule area and directly compared to the PCM results. Due to the higher resolution power of TEM, res pirable fibers of all dimensions were recorded (resolution limit was about 0.02 fim in diameter). .. Work Practice and Control Techniques Work activities in these nine establishments at the time ofair sampling, the dust control techniques, and standard of ventila tion are summarized in Table I. In the service garages, special ization was nota feature and tasks were allotted as the mechanic became available with each spending about 10-75 percent of his time on brake'work. Dust control technologies in brake and clutch work included wet and dry wiping, and the use of a squirt water bottle or aerosol can organic solvent. Garage C'used a Survey by Questionnaire combination of squirt water tu>ttle,.wet wiping, and then com In addition, the nine establishments were surveyed through a . pressed air stream for drying. However, three workshops (A, D, standardizedquestionnaire designed to obtain information about and I) did not provide any form of dust control measures. Tra work practices, the use of dust control measures and personal ditional compressed airjet cleaning has long been abandoned at protective equipment, the use of asbestos products and substi these workplaces. Most younger workers stated that this is due tutes,thecurrentpractices ofriskmanagementincludingtraining to die proper automotive trade training provided by technical of Workers, and provision of safety information in the form of colleges in Sydney. "'roper labelling and material safety data sheets (MSEJS). Hie Among the three brake bonding workshops, shops G and 9 jestionnatre was completed in consultation with the employer H are specialized businesses working full-time in the activ add the'relevant workers at each establishment. ities of cutting, radius grinding, curing, and packing. Radius grinding and cutting which would potentially release asbestos- containing dustwere performed for aboutone to two hours every RESULTS This small-scaled cross-sectional survey indicated that both chrysolite-containing products and substitutes were widely used lit the nine workshops. However, there was an increasing ten dency for them to lean toward tire use of non-asbestos products wherepossible, apparently driven by the marketsupply situation day. Although both processes were provided with local exhaust ventilation, area contamination with asbestos dust was easily discernible. Some exposed workers in these workshops were provided with regular health surveillance (chest x-ray and lung function tests). Approved disposable-type dust respirators were worn by some workers during cutting and radius grinding. and die healthconcern ofthe community and the workforce. The substitutes used in the brake friction materials encountered in PCM Results these workshops incWedmotlfic oxides and synthetic mineral A total of68 (tl personal, 57 area) samples were collected. and tiiganjc fibers including fiberglass, wollastonite, graphite All the resoles were below the current Australian occupational .fibers,parbon-fibers,.kevlar. and steel fibers. exposure standard of 1.0 &mL for chrysotile (under review, see - Ttaej'spiteyalso revealed that all replacement clutches and reference {5)) and the exposure standard of05 f/mL in the State gasketej-.arid-most disc brake pads were asbestos-free and sup of New South Wales. plied to the automotive service industry in (he form of factory- Details of the air sampling results determined by PCM, the .made order parts. However,'the majority of replacement drum types of. sample, and the work activity are presented in 'brake linings, still used in cars ofolder models and in buses and Table II. Respirable fibers were present in most (25 out of 36) -'coagheS.'.were still chrysotile products. air samples from the service garages. The task-specific liber 'Hie five:service garages in this study did not conduct any concentrations were all below the reportable detection limit of brake.re-lining-or re-bonding work. According to them, it is 0.05 OftiL. The highest short-term exposure levels (geomet 'ajready-aji industry-wide practice that worn drum brake shoes ric mean = 0.11 f/mL) were found in a brake bonding work and clutch discs.were collected, distributed to, and re-processed shop (shop G) which is an old-fashioned workplace specializ r^:-$6^alized.brake bonding establishments. Garage workers ing only in the reprocessing ofasbestos drum brakes. Although ? 4 y f HWBUI0007676 1 and (e-g.. wake t disstosizard these Jfair ltilasrialtanic nt of : and quirt ed a :om- k.D, Tra. sd at WW> gpr 4 4 e t 4 4 i 4 ? 2tivdius >tosvery aust ssily irere .ung vere f ted. mal see tate ; > in 36) ber 6 tof tet- ft igh AUTOMOTIVE SERVICE WORKER CHRYSOIUE EXPOSURE Establishment TABLE l Work activities and control measures Work activities*. Frequency Controt techniques . Sendee garages for passenger and light commercial vehicles A Replaced BM & BD 6 h/day B Replaced BD & checked BM 6 h/week C Replaced BM&BD 6 h/week D Replaced dutch Service depot for buses E Replaced BM Biate bonding workshops F Bonding & RG G Bonding, pitting, RG & packing H Cutting, RG & packing Gasket processing workshop 1 Machine cutting & stamping Occasionally 3 h/week 1 h/day 8 h/day S h/day 2 h/day None Aerosol spray Squirt water bottle + compressed air drying None Dry wiping, respirators Respirator Respirator None None *BM=duim brake; BD= disc bake; RO "radius goading; LEV=local exhaust ventilation. v-t Ventilation standard Natural, good Natural,-good' 'Natural, good * .Natural, poor Natural, good LEV, good LEV, good LEV, good NataraUfair TABLE H Air sampling results by phase-contrast microscopy (PCM) Sample Establishment type* Work activity Sampling No. of time (min) samples Fiber concentration (fftnL) GM Range - Service garages for passenger and light commercial vehicles A P BM&BD 77 A 77 B P BM&BD 80 A 75 C P BM&BD 135 A 135 D P Clutch 125 A 125 Service-depot for buses E- P A BM 125 125 Brake bonding workshops FP A GP A HP A Bonding & RG Bonding, cutting, RG . & packing Packing Cutting & RG 80 scr ~130 -125 125 120 Gasket processing workshop I P Cutting & stamping A -100 -100 1 <0.05 . 5 <0.05 1 <0.05 6 <0.05 1 <0.05 6 <0.05 1 <0.05 7 <0.05 <0,05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 ., 1 <0.05 <0.05. 7 <0.05 <0.05 1 <0.05 <0.05 8 <0.05--<0.17 <0.05-<0.17 2 0.11 0.07-0.16 6 <0.05 <0.05-0.04 i <0.05 - <0.05 6 0.04 0.03-0.07 2 <0.05 <0.05 6 <0.05 <0.05 AP = personal sample; A = area sample; GM=geometric mean; see Table I for other-abbreviations. 8Three samples were taken for only 20 minutes. HWBUI0007677 TEM (no. o( fibres /ISO fields) P.YEUNGETAL respirable fibers were found in ail the air samples from the gas, let^Wdessing Workshop (shop I), the fibre concentrations Were all belowjthe reportable detection limit of 0.05 f/mL. - ".'.feiMfiaS or area sampling apparently did not cause a major difference in results, probably due to the very low level of ex' posittein most of the workshops. However, in shop G, personal exposures (re = 2/ concentration--0.07-0.16 f/mL) were obviouslyhigherttian the area sampling results (ail below 0.05 f/mL) .Which,weie taken for the same processes and for the same sam pling jdtadtion. \ It i$:. important to note that the fiber levels reported in this study were, all short-term task-specific exposures (less than two hours).which covered 'only periods of work where peaks'of expoStre Were expected The fimeweighted average (TWA) daily or weekly exposures would be many times lower, as indicated by tfie frequency of particular work activities. sourced from general pollution. In the two samples collected from the bus depot (Garage E) during drum brake maintenance, the fibers were mostly very line forsterite and amorphous silica which are the thermal degradation products of chrysotile. These fibers would have been too fine to be counted under PCM (i.e, diameter <0.2 pm). In brake bonding work, 88 percent of the fibers from the six samples were chrysotile (range -- 63-100 percent). In gasket processing, 78 percent ofthe fibers were chrysotile(range = 709396, n=3). Despite (be differencein resolutionpower, the PCM andTEM data (for all fibers) show a positive correlation (r =0.79) (see Figure I). When the diameter differences of the two sets of data (for all fibers) are adjusted, it is shown in Figure 2 that a very strong positive correlation exists between die two methods (r = 0.90). f t * TEM versusPCM Results Fiber Dimensions Due to its higherresolution and analytical power, TEM could All the countable fibers were less than 50 fim in 'length. Indicate fire presence of fine fibers not detected by PCM, and The percentage diameter distribufiblSsTts measured by TEM are identify different types of fibers: chrysotile, organic, or mineral, shown In Table IV. The median diameter on samples taken from lit the 16 samples selected for TEM analysis, the TEM results the sendee garages (passenger cars) was 0.5-1.0 ftm. and was . were generally higher than the corresponding PCM counts be- 0.2-0.5/rm forbrake bonding and gasketprocessing workshops, - ' cau$e highenergyshearing processes (e.g., cutting and grinding) while that for the bus service depot was 0. l-=0.2 pun. Most ofdie . tend.td liberate finer particles and fibers. A comparison of the respirable fibers (8496, mainly forsterite) from the bus service - TEMand PCM results is given in Table Iff, For the purposes of depot were below 0.2 jim in diameter which is thepractical res ^ ' ^bihparison, the actual calculated PCM results are used in this olution limit ofPCM. It is also important to note that 34 percent and 44 percent ofthe respirable chrysotile fibers taken from the '' QnysotHc fibers were only delected by TEM in one (in brake bonding and gasket cutting workshops were below 0.2 inn Garage- C) of the seven air samples collected from the ser in diameter. > vice: garages,'resulting in a chrysotile fiber concentration of The actual size distributions of the fibers sampled from the 0.004 CfiuL fdr that sample. The other fibers found were mostly four types of establishment, as determined by TEM, are pre organic fibers (e.g., calcium sulphate) which presumably were sented in Figures 3-6. V TABLE HI A comparison of PCM and transmission electron microscopy (TEM) results GM-fiber concentration (f/mL) Type.oLj establishment Work type/ activities Service garages for cars . Service depot for buses' .Brake bonding ... V' : ;6asket processing All processes Brakes Clutch Brakes P A Total (brake bonding) No. of samples 4 1 2 3 3 6 3 16 PCMA (all fibers) 0.006 0.003 0,009 0.06 0.05 0.05 0.01 0.01 , TEM (chrysotile) <0.01 <0.01 <0.01 0.07 0.05 0.05 0.02, 0.02- TEM (all fibers) <0.01-0.01 <0.01 0.1 lc 0.09 0.05 0.07 0.02 0.03 TEM (ns, of flbres/ioo fields) HWBUI0007678 W Sected ranee, silica These t (i.e., m the jasket =70- T f * * * TEM ) (see ets of that a *.thod$ 4- Mgth. Mare (from d was hops, he iressrcent in (he 2ftm m the : pre- AUTOMOTIVE SERVICE WORKERCHRYSOTTLE EXPOSURE aO> PCM versus TEM data (adjusted for fiber diameter). HWBUI0007679 P. YEUNG ETAL. TABLEIV Percentage size distribution by TEM Fiber diameter (fim) distribution in percent t # fibers Type of establishment counted ii ' I Semce garages--car (all fibers) Service depot--bus (all fibers) 17 79 Brake bonding (chrysotUe only) 291.5 Gasket processing (chrysolite only) 37.5 ( . Shaded ansa represents the proportions of fibers not `countable* by PCM. DISCUSSION Thethree brake bonding workshops participating in this study This;smali study suggests that there is widespread replace collectively indicated that thegreatmajority ofworkintheindus mentofchrysolite in friction materials used in theAustralian au tryinvolved the use ofchrysotile-containing products. However.. tomotive industry. The.use of substitutes for chrysotile Is most due to the continuouslyincreased introduction into the market of | evident ju brake disc pads and clutches. However; chrysotile- asbestos-fiee clutch kits and disc brake pads, business activities j containing dram brake linings continue to be manufactured and in the rebuilding industry are rapidly decreasing. imported into Australia in large quantities, predominantly for As shown by the air dhuifflestaken from the four service -I use in the aftermarket industry for older model passenger cars garages (passenger cars), the respirable fiber concentrations I and heavy vehicles. were very low and all below 0.05 fi'mL (the detection limit of HWBUI0007680 J automotive service worker chrysotile exposure ' its study eindusiowever,tarketof .ctivities service ltrations limit of Diameter (fttn) "Shaded Area = fawns notcountable by PCM FIGURE 4 Fiber size distribution (all fibers)--Bus service depot Shaded Area = Ftbera not countable by PCM I : FIGURE 5 .' Fiber size distribution (chrysotile)--Brake bonding. .........'i: 'ft: ` . R YEUNG ETAL, PCMj.'.TheSe findings, contrary to those of many previous overexposure studies that indicated significant exposures, may attributed- to garage workers' increasing awareness of the ' hazard?.of asbestos, which has led to the use of wet methods to replace the traditional compressed air jet The interpretation is reinforced by the observation that chrysolite fibers were identi fied' Sy TEM only in the persona! sample from Garage C where compressed, air. was used for drying after some wet cleaning processes. No. asbestos fibers were detected in any of the sam ples.taken. from Garages A, B, and D where only a wet cleaning method Was used. Although there was no practical difference in PCM results between servicing bus and passenger cars, fiber concentrations as determined by TEM for servicing buses wens an order of magnitude greater than for passenger cars. TBM analysis shows that!84 percent ofthe fibers found in the samples taken from the bus service depot (Garage E) were too fine (less than 0.2 ftm in diameter and'between 5-20 fim in length) to be detected by PCM. The fibers were mainly forsterite which is a thermal degradationpioductofchiysotile.These findingscanpossibly be explained by the greater extent of wear and tear in the friction material during braking of heavy vehicles, and the failure of Garage'E to use wet cleaning methods during brake service. The findings raise concerns about the likely higher exposure to chrysolite, particularly to the very fine fibers not detected by PCM, during brake service to other types of large vehicles (e.g.. coaches, trucks). More studies may be needed before a valid conclusion can be reached on the likely exposure levels for the service of.heavy vehicles. In brake bonding, exposure to chfysotile was demonstrated. Although the exposure level may still be low (especially af ter adjustment for a 8-hour workday), the possibility of area contamination has caused health and environmental concerns. In these workplaces, improvements to control measures and personal protection and housekeeping practices are necessary to reduce the health risk and possible contamination of the environment PCM is the international regulatory method for the deter mination of airborne asbestos fiber concentrations. However, as shown in this study, PCM is not able to detect the very many small fibers (<0.2 fim in diameter) generated by highenergy shearing processes (e.g., cutting, grinding, and sand ing) of asbestos-containing materials. For this type of processes, PCM may underestimate exposure and thus the health risk; and TEM should be used as an aSjuncfto PCM in any regular air monitoring program. COt A llW(. HWBUI0007682 sure to ted by Ue.g,, i valid :or the , ^ *** Crated. Hy aff area teems. 3 and essaty of the & 9 o i deterwever, 5 very high- ^ * sandtesses, . * k; and Jar air . * v *' CONCLUSION AND RECOMMENDATIONS Although it was a small scale cross-sectional study, the fol lowing conclusions can be drawn from the results: Jt The use of substitutes for cluysotile is quite common for brake disc pads, clutches, and gaskets in Australia. However; chiysotile-containing dram brakelinings co ntinue to be manufactured and imported into Australia, predominantly for use in the aftermarket industry for older model passenger cars and heavy vehicles. All the air sampling results from this study (service garages, brake bonding, and gasket processing) were below the current Australian occupational exposure standard of 1.0 f/mL for chrysotile and the New South Wales State's exposure standard ofOJS fifaL. Task-specific exposures ofcar mechanics to chrysotile during service of brakes and clutches were typicallyless than the PCM detection limit of0.05 f/inL. These low levels can be attributed to the.use of wet cleaning or aerosol spray methods in recent years to replace the traditional compressed air jet cleaning. Brake service to heavy vehicles can generate substan tial number ofvery fine fibers which are not detectable by PCM. More studiesare needed to quantify the likely exposure in brake work for heavy vehicles. Area contamination by asbestos debris in brake bond ing workshops raises health and environmental con cerns. The use ofasbestos in theseworkshops should be bettercontrolled. An improvedcontrol program should include education of exposed persons,- isolation of asbestos work, control by ventilation and personal pro tection, maintenance of ventilation system, and good housekeeping measures necessary to reduce the inhala tion ofdust ACKNOWLEDGMENTS This work was funded by the Priority Existing Chemicals As sessment Prqgjaig of Wotksafe Australia's National Industrial Chemicals Notification and AssessmentScheme. TEM analysis was conducted by Alan Rogers and Gary Conaty. DISCLAIMER The conclusions reached and scientific views expressed-in this article are the authors' and do not necessarily reflect those of the organizations in which they work. REFERENCES . 1. Sheehy, J.W.; Cooper, T.C.; O'Brien, D.M; et alrjCbijhptof.As- bestos Exposure During Brake Dram Service, pBfHS .OOSt0 Publication No. 89-121. DHHS, Washington; DClf 198?). " { 2. Lynch, J.R.: Brake Lining Decomposition Products; IAifPoIioliori Cont Assoc 18:824 (1968). :- 3. Rogets.-AJ.; Yeung,P.;Johnson,A;etaL:T!^iidsiaOccupational Groups and Industries Associated with Australian Mesothelioma Cases 1979-1995. Ann Occup Hyg41(l):123-128 (1997). 4. Yeung, P.; Rogers,. A.; Johnson, A: Mesothelioma in Different Occupational Groups and Industries 1979-1995. Proceeding! of 16th Annual Conference- of'Australian Institute of Occupational , Hygienists, Albuiy, New South Wales, 28-November-2 December (1997). 5. National Occupational Health and Safety Commission. Chiysolile (White Asbestos) Proposed National Exposure Standard for the Occupational Environment, Wotfcsafe Australia, Sydney, Decem- ber (1995). 6. Cheng, V.K.t.; O'Kelly, FJ.: Asbestos Exposure in the Motor --v hide Repair and Servicing Industry in Hong Kong, J Soc C ; Med 36:104-106 (1986). '" 7. Kauppinen, T.; Korironen, fC: Exposure to Asbestos Dust birring Brake Maintenance ofAutomotive Whicles by Different-Methods', hid Hyg Assoc J 48(5):499-504 (1987). ' ^' 8. Plato, N.; Tomling, G.; Hogstedt, C.; et al An Index of Past As bestos Exposure as Applied to Carand Bus Mechanics. Ann Occap Hyg 39(4):441-454 (I995)i 9. Rodclspetger, K.; Iahn, H.; Bracket, B.; et ai.: Asbestos Dust Ex posure During Brake Repair. Am J Ind Med 19:63-72 (1986).- 10. Sheehy, J.W.; Cooper, T.C.; O'Brien, D.M.: Control of Asbestos Exposure During Brake Drum Service. Appi hid Hyg 4(12):314-- 319 (1989). . 11. National Occupational Health and Safety Commission: Asbestos: Code of Practice'and Guidance Notes--Guidance Note oh-(he Membrane Filter Method for Esdmadng Airborne Asbestos putt, Australian Government Publishing Services, Canberra (1988). \ V y * * * HWBUI0007683