Document b5ZeE399y1jRbDQ8pD4D4OXO3

FILE NAME: Z< DATE: DOC#: Z< DOCUMENT DESCRIPTION :ZZZZ dZDZZZ^Z Ann. Occup. Hyg, 2014, 1-15 doi: 1O.1093/annhyg/meu093 _0115 ;'\(; Cr1(yturco SOC,O~i 'or WorKer H~,)o)'n ProleCliOf' AMsebcehstaonsicEsxipnoAsuurteomamotoinveg RTerpanaisrmSihssoipons Natalia SaIazar Maria Fernancla CeIy-Garda Patrick N. Breysse and 1 2 1 J , 1 Juan PabIo Ramos-Bonilla ,* oo I.Department of Civil and EnVironmental Engineering, Universidad de los Andes, Bogota, Colombia opklOs University, Baltlmore,MD, USA $' :ol " 2.Dlvision of Environmental Health Engineering, Bloomberg School of Public Health,Johns H 49 ext 2811, 2810; fax: +57-1-3324313; e-mail: Jramos@Juniandesedu.co ~ 3' *Author to whom correspoSnudbemnictetesdho21ulMd baercahdd2r0e1s4se; dr.evTiesle:d+257O-1c-t3o3b9e4r 92014; revised version accepted 9 October 2014. 0- 3 ABSTRACT Objectives: Asbestos has been used m a broad vanety of industrial products, including countries that clutch discs of have analyzed ission system of vehicles. Studies conducted in high-income mechanics have concluded that these workers are exposed the transm personal asbestos exposures oftransmission concentrations in compliance with the US Occupational Safety and Health AdministratIOn to asbestos (US OSHA) occupational standards. Clutch facings are the friction component ofclutch discs. Ifclutch efore installation in the vehicle. facings are sold separated from the support, they require manipulation b ing clutch facings is performed by a group of mechanics known as The manipulation ofasbestos contain eters, and includes drilling, countersinking, riveting, sanding, and occaSionally grinding, tasks that es are not rcrieavnpoprotetednitniaslltyudrieelseacsoenadsubcetsetdosmfibheigrsh,-einxcpoomsiengcothuentmrieesc.hTanhiicsss. tTudheysaenmalaynzeipsupleartisoonnaalcatisvbiteistos expo- sures of transmission mechanicpsatighnats minantiwpuolattreacnlsumtcihssfiaocningresp. air shops (TRS) were conducted in ~ o Methods: November Air sampling 2012 and July cam 2013 in Bogota, Colombia. Four workers employed in these TRS were samrsonal samples C 0- V> o = pled (i.e. three riveters and one supervisor). Personal samples (n 39), short-term pe (n 8), and background samples (n =2) were collected ::> Z o = (n == 49), area samples (n during 3-5 52), blank samples == consecutive days, following US National Institute for Occupational Safety < " 3 er in both TRS and Health (US NIOSH) methods 7400 and 7402. Asbestos samples were analyzed by an American ~ Industrial Hygiene Association accredited laboratory. of the days sampled, all riveters were exposed to asbestos concentrations ;~ o N Results: On at least one that exceeded the US OSHA permissible exposure limit or the Colombian permiSSible limit value. (4.3%) exceeded .j... Additionally, from the forty-seven 30-min short-term personal samples collected, two the US OSHA excursion limit of 1 f cm-3 this study, we identified that the working conditions and use of asbestos containing Conclusions: In transmission products expose transmission mechanics to asbestos concentrations lth of that exceed both the these workers are of Colombian and OSHA standards. The potential consequences for the hea great concern. KEYWORDS: asbestos, chrysotile, clutch disc, Colombia, exposure assessment, transmission mechanics The Author 2014. PublIshed by Oxford Umverslty Press on behalfof the Bntlsh Occupational HygIene SOCIety Page 2 of 1S Asbestos exposure oftransmISSIon mechanics INTRODUCTION 30-60% of the friction material (Yeung et al., 1999; mphiboles have not been detected Asbestos-containing materials are good acoustic, thermal, biological, Jlang et al., 2008). A in previous studies of transmission mechanics (Blake heat and fire insulators, and resist and chemical attack (Thompson and Mason, 2002). et al., 2008; Jiang et al., 2008). Beginning in the 1980s, products Because of these characteristics, asbestos has been used in a wide range of industrial products such as chrysotile was gradually replaced in clutch used in the USA with other non-asbestos substitutes thermal insulations, friction products (e.g. brake and ilding materials, (Jiang et al., 2008). In 1975, the US National Institute for transmission products ofvehicles), bu eat-resistant textiles (Pierce et al., 2008). Occupational Safety and Health (US NIOSH) re and h A causal association between asbestos exposure veral diseases has been established (lARC, Research on warned about the potential risk ofasbestos exposu of workers that handled asbestos containing brake parts and clutch discs (NIOSH, 1975). In addition, and se 1998). The International Agency for (IARC) has classified all types of asbestos several exposure assessment studies conducted in is- Cancer (i.e. chrysotile and amphiboles) as carcinogenic to Australia and USA have concluded that transm are exposed to asbestos concentra- humans (Group I; IARC, 1998). Some of the diseases lation of asbestos fib- sion mechanics tions in compliance with both the US OSHA PEL that might result from the inha ers include lung cancer, asbestosis, and mesothelioma and EL (Yeung et al., 1999; Boelter et al., 2007; den, 2008; (Kanarek, 2011). Every year asbestos exposure is Blake et al., 2008; Cohen and Van Or et al., 2008). These studies describe the activi- responSible for half of the occupational cancer deaths ]i.1I1g ties performed by transmission mechanics as only worldwide COMS, 2004). In 2011, the Colombian Ministry of Social removing the entire old clutch disc and replaCing it 007; Blake et al., Protection established for the first time an asbestos occupational standard (i.e. Resolution 007, esolution 007, the with a new one (Boelter et al., 2 2008; Cohen and Van Orden, 2008). Nevertheless, there is a study conducted in Japan during the 1980s 2011) (MSPS, 2011). In R American Conference of Governmental Industrial and published in 2006, that reports high PCM conactivities (Le. Hygienists (ACGIH) threshold limit value (TLV) centrations due to the manipulation grinding and leveling) of brake linings for asbestos was adopted as the Colombian permislue (PLV). Thus, the Colombian PLV is machine and clutch facings in three companies involved in s ~ sible limit va 0.1 f cm-3 for an 8-h time weighted average (TWA) the reprocessing of automobile brakes and clutche o 0. phase contrast microscopy equivalent (PCME) asbes- (Sakai et al., 2006). Previous studies of our research group conducted <f' o " Z tos concentration [We use the term PCME to mean asbestos content, as described on brake mechanics in Bogota found that the manip- o < " 3 counts corrected for below. It is important to note that this is different ulation of asbestos containing brake products (e.g. lted in the release of impor- cr" ~ ng of PCME in ISO 10312:1995 grinding, drilling) resu tant amounts of asbestos fibers, exposing the work- from the meani (ISO, 1995)]. In the USA, the Occupational Safety and Health Administration (US OSHA) permissible for asbestos is 0.1 f ers (Cely-Garcia et al., 2012, 20l4). Transmission mechanics could be facing a similar situation, since cings (Le. the friction exposure limit (US OSHA PEL) cm-3 for an 8-h TWA PCME concentration. The US OSHA has also established an excursion limit (US asbestos concentration asbestos containing clutch fa component of clutch discs), are commercialized in Colombia detached from the clutch plate (i.e. OSHA EL) of 1 f cm-3 PCME for a 30-min exposure period (OSHA, 2013). [Instead metallic support). The clutch disc is comprised the clutch plate, of using the term US OSHA EL, we previously used of two clutch facings attached to clutch facings that are detached from the plate the term 'short term exposure limit (STEL)' (Cely- and require manipulation before installation. The cur- Garcia et al., 2012, 2014).] Asbestos containing clutch parts have been used rent study analyses personal asbestos exposures of ring the manipulation since the early 20th century (Cohen and Van Orden, 2008; Jiang et al., 2008). Traditionally, chrysotile was lutch parts, comprising transmission mechanics du process of asbestos containing clutch facings in Bogota, Colombia. the type of asbestos used in c Asbestos exposure oftransmission mechanics Page 3 of 15 the use of compressed air or rags to clean the system, METHODS In 2012, a comprehensive and detailed census ofbrake this was not the case for the workers sampled in this the sampling repair shops located in an area of the city of Bogota study. To avoid study-induced bias from n, all workers were instructed to conduct their where automotive repair shops cluster was developed. this database, three trans- campaig daily activities without modifications. The activities During the development of mission repair shops (TRS) were identified. Two S 1 and TRS2) collaborated performed were recorded in activity diaries. Shortterm personal samples were collected during the ipulation activities of clutch facings, and during of these shops (i.e. TR with this study. The study methods and design were mittee of Universidad de man cleaning activities. The duration of the partial period approved by the Ethics Com 10s Andes, and workers from the TRS that participated sample was longer when no manipulations were conwere expected in the study signed an informed consent. Personal partial period, personal 30 min, and area consecutive days ducted, since air fib er concentrations to be low. Blank samples were collected for each sampling day, and background samples were collected dur- air samples were collected during 3 in TRSl (8-10 November 2012), and 5 consecutive ), during the work- ing one night at each shop. All personal samples were analyzed by PCM and TEM. Background and blank analyzed by PCM. days in TRS2 (11-15 July 2013 shift. To reduce the chances of overloading the filters s, the work-shift samples were Study design and methods were similar to those during the collection of air sample ivided into shorter partial-period sampling win- used in previous studies by our research group (Celye collected was d dows. Air sample collection and analysiS followed US Garda et al., 2012, 2014). Air samples wer XRSOOO pumps (SKC-Inc., Eighty fie NIOSH methods 7400 (NIOSH, 1994a) and 7402 7400 provides using AIRChek Four, PA, USA) operated at a flow rate of- 2 LPM, con- (NIOSH, 1994b). US NIOSH method unts using phase contrast microscopy (PCM), nected to 2S-mm cassettes equipped with SOmm conE filters fiber co and reports total fib er concentration according to ducting extension cowls, holding 25-mm MC ~m pore size(SKC Preloaded Cassette, SKC- selected counting rules. US NIOSH method 7402 scopy (TEM) to with 0.45 Inc.). Flow rates were calibrated at the beginning and at utilizes transmission electron micro ine fiber identity and provides asbestos fiber the end ofeach sampling window using a Defender 510 tor (BIOS determ counts, asbestos type, and the fraction ofobserved fib- High or 520 High BIOS International Calibra utler, NJ, USA) following standard pro- ers that are asbestos. International, B :;: cedures. Samples were reported as suspect if the differ- 8 Personal samples were collected in a group ofTRS ters, who manipulate asbestos ence between the initial and final flow was above 5%. o0- V> workers known as rive and non-asbestos containing clutch facings to attach Samples were analyzed by Forensic Analytical Analytical Laboratories, ::l Z ? < them to the clutch plate before installation in the Laboratories, Inc. (Forensic Inc, Hayward, CA, USA), an American Industrial 3 " er vehicle. In TRS 1, there were two riveters (Ri, R2) in tion of clutch facings, and spo- Hygiene Association (AIHA) accredited labora- ~ charge of the manipula unt of work, a third tory that also partiCipates in the National Voluntary rogram (NVLAP). TEM radically, depending on the amo worker (Wl) who is the supervisor of the TRS, also Laboratory Accreditation P analysis was performed at 100 kV accelerating volt- performed manipulations. In TRSl, workers RI, R2, and W1 did not repair the transmission system of the transmission parts in age and -2500x magnification to count fibers >S p.m, using a Philips CM 12 TEM (Eindhoven, Netherlands, agnification of 10000x was vehicles; they only prepared the order to install them in the vehicles, and did not use installed in -1991). A m used to determine fiber dimension and countability of any compressed air. The workers in charge of repairing the vehicle's transmission system worked in a differ- In TRS2, the riveter fibers close in length to 5 pm. The energy dispersive X ray analyzer (EDXA) instrumentation was manufacSA; installed in 2007), ent area, and were not sampled. (R3) conducting the manipulation processes was also mechanic in charge of repairing the vehicle's transdoes not clean tured by Evex (Princeton, NJ, U and consists of a quantum dot detector (QDD) with standard window and digital ADC/MCA analyzer and the mission system. R3 reported that he icle's transmission system. Although repairing QDot power supply (Forensic Analytical Laboratories, the the veh transmission system of the vehicle could involve personal communication). Page 4 of 15 Asbestos exposure oftransmission mechanics PCME personal concentrations were used to com- not result in important differences on the 8 h peME sensitivity analysis showed pare against both the Colombian and the US OSHA concentrations. In fact, the that the compliance status of the samples did not standards. To estimate PCME concentrations, PCM rrected with the fraction ofasbes- change when using the LOD instead ofV2 LOD. When concentrations were co tos fibers to total fibers (ElF) reported byTEM (NIOSH, this usage of the term PCME is dif- work-shifts ended before 8 h or the worker left the shop, fiber concentrations were assumed as 0 f cm-3 for the time remaining to complete the work-shift. 1994b). [Note that ferent from that in ISO 10312: 1995 (ISO, 1995)]. PEL and Colombian PLY set limits Area samples were collected in both shops at a The US OSHA for asbestos personal exposures during work-shifts of breathing height of 1.5 m. In TRSl, the collection of determine if fibers could S-h per day. Nevertheless, in multiple occupations in area samples was done to igrate outside the manipulation area (MA), expos- Colombia, as happened with the mechanics involved in the current study, the daily work-shift is longer. The s extending beyond m ing administrative staff or customers. In TRS1, the office facilities were physically separated from the with a duration approach to deal with work-shift Sh differs between the two standards (Le. US OSHA manipulation area, and area samples ere collected at the office entrance (OF), and PEL and Colombian PLY). One ofthe options recomal Manual is using of-Sh w at the MA. TRS2 did not have physically separated mended in the US OSHA Technic orst partial period sampling windows that add up areas, since this shop only had one large area where were con- the w 8 h for each work-shift to estimate the S-h TWA PCME both administrative and repair activities sess fiber migration in TRS2, short-term concentration, for comparison purposes against the roach was ducted. To as area samples were collected at 1 m (AI) and 2 m (A2) US OSHA PEL (OSHA, 200S). This app current study. For short-term personal from the manipulation equipment (i.e. emery disc), ples used in the samples, the 30-min PCME personal concentrations ainst the US OSHA EL of 1 f cm-'. simultaneously to the short-term personal sam collected during the manipulation processes. Fig. 1 shows the location of the area samples in each TRS. were compared ag In the case of the Colombian PLV, the regulation work-shift exceeds 8 h, the All area samples were analyzed by peM, and in TRS2, stipulates that when the PLY must be adjusted follOWing equations (1) and (2) area samples collected at 1 and 2 m during days in which the 8h personal concentration exceeded the VS OSHA (MSPS, 2011): PEL, were also analyzed byTEM (Le. Day 1 and 2). (1) Asbestos percent bulk content ofthe most common clutch facings used in the shops sampled was deter- mined using method EPA 600/R-93-116 PLM, by z o Forensic Analytical Laboratories. None of the labels of "3'" PLVc=CFxPLV (2) the clutch facings specified asbestos content. However, c.".r,- we received feedback from the workers regarding their .-"" where CF is a correction factor, hd is the number of perception of asbestos content. Two of the brands sent as asbestos containing prod- N o -"" hours worked per day, and PLVc is the corrected PLY. for analysis were reported ucts, and the third brand was reported as asbestos free. In TRS 1 the work-shift was 8.5 hiday, and in TRS2 was 9 hi day. For comparison purposes against the LY is 0.091 f cm-3 for To capture potential variability of asbestos content, four clutch facings per brand were analyzed. elative humidity were recorded on Colombian PLY, the adjusted P Temperature and r TRS1 and 0.OS3 f cm-3 for TRS2. hen PCM concentrations were below the limit MAs using aHOBO VI 0 Temperature Relative Humidity ourne, MA, USA). W of detection (LOD), one-half of the LOD was used Data Logger UlO-003 (ONSET, B for calculation purposes. To determine the potential impact of using one-half of the LOD instead of the RESULTS LOD, a sensitivity analysis was conducted in personal Description ofthe TRS samples with sampling windows that had concentrasensitivity analysis showed TRS 1 operates -8.5 h per day on weekdays, and 5 h tions below the LOD. The that using the LOD instead ofone-halfofthe LOD did on Saturdays. TRS2 operates -9 h from Monday to I a) I 1 - 1 - - - - - lOm Asbestos exposure oftransmission mechanics b) I--- 4m ----i Page 5 of IS O~disc 12m 12m Work area @ (3 3 I Office Warehouse 4m I-..----~___..ll $o Office and WlIr.hGuse .rea sample Manipulation.r....mpl. (IMj (Of) o A1-Areasample $ A2 - Area sample {Day 1) o A2-ArnSimple (Days 2, 3, 4,5) (a) Location of area samples in TRS 1 (vertical view). (b) Location of area samples in TRS2 (vertical view). :oE o Saturday. Both TRS use asbestos containing clutch a wrench, and holes are drilled in the clutch facings plate. Then, the holes i1- o ::l ally uses non-asbestos con- matching the holes of the clutch clutch facings are countersunk, and if drilling Z o < facings, and TRS 1 sporadic taining clutch facings (i.e. glass fiber). Table 1 presents on the the clutch facings leaves an irregular surface surround- 3'" or a description of the TRS involved in the study. !:; ing the holes, the surface is sanded. In TRS2, the riveter Description ofmanipulation activities ofclutch rubbed one clutch facing against the other to remove clutch facings are riveted facings the debris. Subsequently, the the plate. If the size of the facings does not match the At the TRS sampled, clutch facings are sold without clutch plate. Using the to plate, facings are ground with an emery disc. holes and separated from the ctivities diaries kept during the sampling campaigns, Sometimes clutch facings for specific vehicles are are not in stock. In a it was possible to reconstruct the tasks involved in the ipulation process required to attach clutch facings process of clutch not commercially available or they such occasions, riveters need to adjust clutch facings of improper size to the clutch plate, which includes cutting man to the clutch plate. The manipulation is the same for all types of manual transmissions the edges, grinding, and sanding the products. A flowd in Fig. 2. facings (i.e. both heavy and passenger vehicles). Once the clutch chart of the manipulation process is presente disc has been uninstalled from the transmission system, Air samples results the manipulation process starts with the removal of the facings using a drill. The new A total of ISO samples were collected in the TRSs, rivets from the old clutch clutch facings are attached to the old clutch plate using including 39 personal samples of different duration, Page 6 of15 Asbestos exposure of transmISSIOn mechanics Table 1. Description ofTRS Shops characteristics Type ofvehicles serviced TRSI TRS2 Prepares transmission parts for heavy Prepares transmission parts for and passenger vehicles serviced at the passenger vehicles exclusively serviced shop and at other nearby TRS. at the shop. Number of clutch discs manipulated -12 -1 per day Workers involved in clutch discs 2 Riveters (RI, R2) 1 Riveter (R3) preparation 1 Supervisor (Wl) o c Area of the shop, ceiling height -160 m2 with a ceiling height between -48 m2 with a ceiling height -3.5 m :;: "0" ~ 3.5 and 4.5 m. 0- Office and warehouse area shared 0"....-., Description of office and warehouse Office and warehouse area of -20 sically separated from the space with manipulation area. Work Cl 3 ml, phy manipulation area. Warehouse desk located at - 3 m from the access is through the office. Office manipulation area, close to the exit door located at -10 m from the door. Exit door remained open during manipulation area. The doors of the the entire work-shlft. office and the warehouse remained Description of manipulation area open during the entire work-shift. Area of -13 m2 The manipulation area was embedded in a larger area where other mechanics performed Area of -4 m2 with a ceiling height of - 3 m, which was o.s m lower than the rest of the shop. their work. Manipulation equipment and 1 drill 1 drill ~ materials 1 countersink 1 countersink cCL V> C 1 rivet machine 1 rivet machine " Z 1 emery machine (With emery stone 1 emery machine (with emery stone c 3""' and emery disc) and emery disc) cr" ~ Ventilation system ... Sandpaper Sandpaper ;1"- N Consisted of a self-made extractor No ventilation system in the shop, o hood located above the countersink except for the natural ventilation prOVided by the exit door. This door aonpderraitveedt.mTahcehrienaerse, wtwhoicshkywlaigshrtasrely remained open during the entire in the roof, one located above the work-shift. manipulation area, which remained open during the sampling days. Two exit doors remained open during the entire work-shift. Asbestos exposure oftransmission mechanics Page 70flS Table 1. Continued Shops characteristics TRSl TRS2 Cleaning activities of the manipulation Every day at the end of the shift the Cleaning activities under dry area shop was cleaned. This was done after conditions were performed once sprinkling small amounts ofwater during the sampling campaign at the on the floor. Occasionally workers end of the week. removed dust from the machines with their hand or a broom in dry conditions. Respiratory protection equipment Workers wore working clothes. Worker wore working clothes. In some cases workers used The riveter used a half face-piece inappropriate respiratory protection, air-purifying respiratoron top of a including a piece of cloth or a filtering filtering face-piece respirator. Neither face-piece respirator to cover their respirator met the recommendations nose and mouth. for asbestos protection. Respirators were loose, and occasionally the nose was uncovered. No 2- J Drill the rivets to separate old clutch faclngs from the clutch plate Hold the new clutch faeings 10 the clutch plate with wrench o::E o Cl. Drill the new clutch facings Use a new clutch plate rh o '" matching the clutch plate holes z o < ":3 er (t Do clutch No ~ Sand clutch faelngs or rub one facing against the other Yes Grind the clutch faelngs to adjust size Install the clutch disc In the vehicle 2 Manipulation process of clutch facings. Page 8 of 15 Asbestos exposure oftransmission mechanics 49 short-term personal samples, 52 area samples, 8 above both standards during two sampling days (i.e. blanks, and 2 background samples. Chrysotile fibers RJ-Day I, R3-Day 2), and was exposed to asbestos were the only type of asbestos identified in the sam- concentrations exceeding 50% of the US OSHA PEL ples collected in both TRS. Eleven TEM fib er counts and the Colombian standard during Day 5 (i.e. R3- were below the analytical sensitivity. One sample was Day 5). Supplementary Table SI, available at Annals suspect because the flow drift was greater than 5% (Le. of Occupational Hygiene online presents all 30-min 5047%). Another three samples were labeled as suspect short-term personal asbestos concentrations and the because the conducting extension cowls were acciden- description of the manipulation or cleaning activi- tally opened when detaching them from the pump, ties associated with each sample. For the concentra- although the filter remained in the cowl and the cowl tions presented in Supplementary Table SI, available was immediately sealed again. One filter was reported at Annals of Occupational Hygiene online, when the by the laboratory as "loaded with particulates" (Le. RI sampling window was shorter than 30-min, 0 f cm-3 DayI ST3). All these samples were used in the TWA was assumed for the remaining time. It is important calculations, and reported in footnotes 'b' and 'g' in to highlight that all the 30-min PCME short-term per- Table 2, and footnotes 'd', 'f', and 'g' in Table 3. No fib- sonal samples collected in TRS 1 were below the US ers were found in the blanks, and both background OSHA EL. However, four samples had TEM concen- samples collected had PCM concentrations below the trations above 0.5 f cm-3, and one sample was above LOD. 1 fcm-3 Two 30-min PCMEshort-term personal sam- During sampling days, temperature in TRSI ranged ples collected in TRS2 exceeded the US OSHA EL of between -15 and 24C in the MA, and between -19 1 f cm-3 Eleven percentage of all the short-term per- and 22C in the office area. Relative humidity ranged sonal samples collected in both shops were above 50% between -36 and 70% in the MA, and between -38 of the US OSHA EL. 2. and 60% in the office area. In TRS2, temperature and During manipulation activities of asbestos and relative humidity were sampled at 1 and 2 m from non-asbestos containing clutch facings, presented 2- J the manipulation equipment (i.e. Al and A2, respec- in Supplementary Table SI, available at Annals of tively). Temperature ranged between -17 and 2rC Occupational Hygiene online, workers reported which in both sampling pOints, and relative humidity ranged type of products was used. The asbestos content bulk between-53 and 72% in sample pointAI and between analysis showed that the two brands reported by -47 and 67% in sample point A2. the workers as asbestos-containing products had a ~ o o 20% content of chrysotile. There was no variation in 0. V> o Personal air samples results asbestos content between the four clutch facings ana- ::l Z Table 2 presents the results of the 8 h TWA and 8.5 h lyzed per brand. The four clutch facings of the brand o < TWA personal asbestos concentrations in TRSI, for reported by workers as asbestos free, had a 25% con- ";3 0' comparison purposes against the US OSHA PEL and tent of fibrous glass and asbestos were 'non-detected: ~ the Colombian PLY, respectively. Both riveters sam- Additionally, Supplementary Tables S2 and 53} pled in TRSl were exposed to asbestos concentrations available at Annals of Occupational Hygiene online pre- not in compliance with both the US OSHA PEL and sent the results of all the personal samples collected in the Colombian PLVc during the first sampling day (Le. TRSl and TRS2, respectively. RI-Day I, R2-Day I), and were exposed to asbestos Table 4 summarizes the 8-h TWA and 30-min concentrations above 50% of the US OSHA PEL and PCME short-term asbestos concentrations of per- the Colombian standard during the second sampling sonal samples collected in both TRS sampled. day (Le. RI-Day 2, Rl-Day 2). The supervisor in TRSI (Le. WI) was exposed to asbestos concentrations below both US OSHA and Colombian standards Area air samples results in all the days sampled. PCM area concentratlO/l results Table 3 presents the results of the 8 h TWA and In TRSl} the three 8-h TWA PCM office area concen- 9 h TWA personal asbestos concentrations in TRS2. trations coIIected on Days 1,2, and 3 were 0.009, 0.002} Riveter R3 was exposed to asbestos concentrations and 0.005 f cm-3} respectively. The corresponding 8-h Table 2. peME 8-h TWA and 8.5-h TWA personal asbestos concentrations for workers sampled in TRS 1 Worker-Day Number of sampling windows Total sampling time (min) TWAPCME concentration using total sampling time (f cm-3 )a US OSHA STANDARD (0.1 f cm-3 for 8-hTWA) Time assumed with Ofcm-3 to complete 8-h TWA (min) 8-hTWAPCME concentration (f c m -3 )a COLOMBlANSTANDARD(0.091 fcm-3 for 8.S-h TWA) Time assumed with 0 f cm-3 to complete 8.S-h TWA(min) 8.S-h TWA PCME concentration (f cm-3)a RI-Day 1 11 508 0.103 0.108b" 2 0,103 b,d RI-Day 2 5 495 0.064 0.066 IS 0.062 RI-Day 3 4 270 R2-Day 1 12 510 R2-Day2 13 480 0.042 210 0.107 0.077 o 0.024 240 O.I11e o O.077b 30 0.022 0.107d 0.073b R2-Day3 6 263 0.088 217 0.048 247 0.046 ;:t.. WI-Day 1 2 533 0.013 WI-Day2g 7 553 0.012 WI-Day3 1 285 0.010 195 O.013e O.014b 0.006 225 O.013 f '<":- ~ ~ 0.0 12b,h ~'" 0.006 s: I:: ~ '" RI: Rlveter I, R2: Rlveter 2, Wl: worker I. ~..... 'PCME concentrations calculated based on PCM concentratIons, chrysotIle fiber counts, and f/F ratIO, whIch are shown In detaIled for each sample IS avaIlable as Supplementary Table S2 at Annals of OccupatIOnal i:l ~ HygIene onlIne. 2i 'TWA PCMEconcentration includes samphng window(s) WIth PCM concentrations <LOO. Total fibers/asbestos fibers ratio was multtphed by one-halfof the LOO for samphng window(s) with PCM ~. concentrations <LOO, o :::: 'Soh TWA PCME concentratIOn not In comphance WIth OS HA PEL of0.1 fcm-'. 2i dS.S-h TWA PCME concentratIOn not in comphance with Colombian PLVc of 0.091 f cm-'. S- 'Soh TWA PCME concentration calculated USIng the worst S-h of the work shift, accordIng with the US OSHA Technical Manual (OSHA, 2008). I::> :::: 'Samples were collected dUrIng 533 mIn thIS day. TWA PCME concentration was estimated for the total samphng tIme, and compared agamst the Colombian PLVc of0 085 f cm-'. ~. "fWA estImatIOn Includes concentratIOns from samples WI Oay2 P2 and WI Oay2 ST2, In whICh the conductIng extensIon cowl were aCCIdentally opened at the end of the sample collectIOn. Cowls were ImmedIately closed and the filter always remained In the cowl. 'Samples were collected dunng 553 mm this day TWA PCME concentratIOn was estImated for the total samplmg tIme, and compared against the ColombIan PLVc ofO.OSO f cm-'. 'tI ~\0 o ......,Vt vI OZ "17 I J;}qw;}AON uo spooi\\ J::IJ1UUJf Aq ,j.lo 'lell 1110i'PJ 0 I\( r j \ljlllm 11 duq WOJJ P;}PBOluMOQ ?...... o .C.l., (Jo Table 3. peME 8-h TWA and 9-h TWA personal asbestos concentrations for workers sampled in TRS2 ~ '~ " Worker-Day Number of Total sampling TWAPCME US OSHASTANDARD (0.1 fcm-3 for COLOMBIAN STANDARD(0.083 f ~ ~ sampling time (min) concentration using 8-hTWA) cm-3 for 9-h TWA) ~'" windows total sampling time (fcm-3)a Time assumed with 8-hTWAPCME Time assumed with 0 9-hTWAPCME ~ s::: of cm-3 to complete concentration f cm-3 to complete 9-h concentration ~ 8-h TWA (min) (f cm-3)a TWA(min) (fcm-3)a <Q., ~ ;,. R3-Day 1 7 461 0.159 19 R3-Day2 7 475 0.195 5 R3-Day3g 4 479 0.024 1 R3-Day4 4 513 0.032 0.153bc,d 79 0.193 b.cf 65 0.025! 61 0.034b 27 0.136de ~~. .,c 0.172e'( ;,. := 0.022! ~ ;,. 0.030 e!' R3-Day5 5 523 0.057 0.061 b.f 17 O.OSOf R3: Riveter 3. 'PCME concentratIOns calculated based on PCM concentrations, chrysotile fiber counts, and flF ratIO, whICh are shown in detailed for each sample is available as Supplementary Table S3 at Annals of OccupatIOnal Hygrene online. '8-h TWA PCME concentration calculated usmg the worst S-h of the work shift, according with the US OSHA Technical Manual (OSHA, 20(8). '8-h TWA PCME concentration not in complIance With OSHA PEL of0.1 f cm-'. 'TWA PCME concentration mcludes a suspect sample that had a flow drift of 5.4%, With a samplIng time of 30-mm and a PCME concentration of 1.084 f cm-'. '9-h TWA PCME concentration not in compliance With the Colombian PLVc of 0.083 f cm-'. 'TWA PCME concentration mcludes samplmgwmdow(s) with PCM concentrations <LOO. Total fibersl asbestos fibers ratIO was multiplied by one-half of the LOO for sampling window(s) With PCM concentrations <LOO. 'TWA estimation includes concentration from sample R3 Day3 P3, in which the conductmg extenSion cowl was aCCIdentally opened at the end of the sample collectIOn. Cowl was immediately closed and the filter always remained m the cowl. vlOl'vl l;>qW;>AON 1I0 spooM l;>JfUU;>[ A:q .la.!" 'Iell fll(1lpl(}I'''';i (ljUlll;/! ulIq WOlj P;)PBOIUMoa Table 4. Statistical summary ofPCME personal asbestos concentrations found in the TRS sampled Type ofsample Worker (shop) Total number (number above the US OSHA PCME asbestos concentrations (f cm-3) PEL or EL) Mean SD Median Min Max 8-h TWA personal samples a Short-term personal samples C RI (TRSl) R2 (TRSl) R3 (TRS2) Wl (TRSl) RI (TRSl) R2 (TRSl) R3 (TRS2) Wl (TRSl) 3 (lb) 3 (1 b) 5 (2b) 3 (Ob) 12 (Od) 23 (Od) 11 (2d) 3 (Od) 0.066 0.079 0.093 0.011 0.172 0.105 0.603 0.065 RI: Riveter I, R2: RIveter 2, R3: RIveter 3, W I: worker 1. 'Calculated USIng the S-h TWA PCME asbestos concentrations shown In Tables 2 and" (Column 6). bValues compared agaInst the US OSHA PEL of 0.1 f cm-". 'Based on the 30-min PCME asbestos concentratIons shown In Supplementary Table SI (Column 5) available at Annals of OccupatIOnal Hygiene onlIne_ dValues compared against the US OSHA EL of I f cm-'. 0.042 0.032 0.076 0.004 0.088 0.048 0.443 0.076 0.066 0.077 0.061 0.013 0.195 0.110 0.432 0.021 0.024 0.108 0.048 0.111 0.025 0.193 0.006 0.021 0.022 0.223 0.021 0.014 ;r~ 0.332 <'":s- 'C'"" 0.212 ~''"" l.653 <:> ;'":: 0.153 ~~ ;:: ';"i ;;;. 'o" ;:: ;i <'> ;::- '"~ 5";:: ..."''"'"C (Jq ....0.... ...tI> vIOL 'vl lJqw;lAON uo spooM l:lJIUU;)f Aq ,ill" 'll:lIl1wi"Pj()J'" il,\ljlllll:" Ulllj WOlj PJpuolu",\OO Page 12 of 15 Asbestos exposure of transmissIOn mechanzcs TWA PCM MA concentrations collected on Days I, riveters. These manipulations are required because 2, and 3 were 0.017, 0.010, and 0.015 f cm-3 respec- clutch facings are sold detached from the support. tively. In TRS2, the 8-h TWA PCM Al area concen- In the TRS sampled, most of the clutch facings used trations ranged between 0.007 and 0.050 f cm-3 (i.e. contained asbestos. Riveters sampled have to perform collected during 5 days). For A2, the 8-h TWA PCM manipulation activities including drilling, counter- area concentrations ranged between 0.006 and 0.183 f sinking, riveting, sanding, and grinding clutch facings, cm-3 (i.e. collected during 5 days). which release asbestos fibers and expose workers. All riveters sampled were exposed to non-compliant PCME area concentration results asbestos concentrations when compared to the US Eight-hour TWA PCME area concentrations in TRS2 OSHA PEL and the Colombian standard. Moreover, were estimated for Days 1 and 2 in sampling points Al (1 m), and A2 (2 m) (Fig. 1\ because on these days some manipulation activities resulted in asbestos exposures exceeding the us OSHA EL. Although personal samples showed high asbestos exposures of ready to install clutch discs are commercially available, ~ the riveter (R3). For this analysis, fiber concentration they are more expensive and were less common in the '"o Cl.. was assumed as 0 f cm-3 during periods when samples TRSs sampled. (t Cl.. were not collected. One of these 8-h TWA area con- To the best of our knowledge, this is the first study 3' 3 centrations exceeded 0.1 f cm-3 (i.e. A2 Day 2 =0.183 that reports asbestos exposures on transmission f cm-3), recognizing that area samples should not be mechanics (Le. riveters) in low- and middle-income used to determine regulatory compliance. The other countries. The results obtained in this study are dif- 8-h TWA PCME area concentrations (AI Day 1 and ferent from the results of the small number of studies 2, and A2 Day 1) had quantifiable asbestos concentra- conducted on this occupational group in high-income tions ranging from 0.024 to 0.050 f cm-3 countries. In 1999, a study conducted in Sydney, Australia found that during the replacement process Comparison ofPCME short-term personal a/1d short-term of a clutch disc, PCM concentrations were below the area concentrations LOO (0.05 f cm-3) (Yeung et al., 1999). A study from A preliminary analysis was conducted to determine the USA evaluated personal exposures to asbestos the migration of fibers in the work area during the among transmission mechanics during activities that manipulation activities. For this, during Days 1 and included unpacking, repacking, and stacking boxes, 2 short-term 30-min area concentrations were col- cleaning asbestos containing clutch discs, and clothes ~ o o lected in TRS2 at points Al and A2 while riveter was handling. This study found that personal asbestos con- Cl.. 'o" manipulating asbestos containing products. PCME centrations were in compliance with the US OSHA :l 30-min Al concentrations ranged between 0.091 and PEL and EL, and reported that the highest exposures o Z < 0.207 f cm-3 Thirty-minute PCME A2 concentrations were associated with stacking unopened boxes (Jiang 3 " 0" ranged between 0.069 and 1.715 f cm-3 PCME con- et al., 2008). Another study conducted in USA in 2003 ~ centration of sample A2 Oay2 ST2 exceeded 1 f cm-3 analyzed asbestos exposures during the removal and Recognizing that the number of samples is small, replacement of asbestos-containing materials in heavy no clear patterns associating asbestos concentration vehicles (i.e. gaskets, brakes, and clutch parts). In this with the distance to the manipulation equipment was study, authors reported that the PCME short-term per- observed. Supplementary Table S4, available at Annals of Occupational Hygiene online shows in detail the sonal asbestos concentrations ranged between <0.043 and 0.099 f cm-3, and TWA PCME concentrations. 30-min personal sample PCME concentrations and ranged between 0.0 11 and 0.052 f cm-3 during different the corresponding 30-min PCME area samples at a sampling periods (i.e. from 336 to 574 min) (Boelter distance of 1 m (AI) and 2 m (A2) from the manipu- et al., 2007). Finally, Blake et al. (2008) reported that lation equipment. during the installation of a clutch disc, the 8-h TWA PCME chrysotile asbestos concentration was 0.0011 DISCUSSION f cm-1 (Blake et al., 2008). All these studies concluded This study describes the manipulation activities of that transmission mechanics are not at excess risk of asbestos containing clutch facings performed by developing asbestos related diseases (Yeung et al., Asbestos exposure oftransmission mechamcs Page 13 ofl5 1999j Boelter et .11., 2007j Blake et al., 2008j Ji.lng some potential explanations for this. First, based on the et al., 2008). However, none of the previous studies activity diaries filled during sampling campaigns, R3 report the manipulation activities conducted by the frequently rubbed one clutch facing against the other to riveters sampled in the current study. Thus, a potential eliminate debris, and this activity was often performed explanation for the low asbestos exposures reported in close to his respiratory zone. In contrast, riveters in studies conducted in high-income countries involve TRS 1 used sand paper for this task, and in only one the fact that in these countries, clutch discs can be occasion during the sampling campaign, one worker directly installed in vehicles without manipulating in TRSl (Le. RI) rubbed clutch facings (Le. sample clutch facings. It is important to highlight that there RI Day2 ST2, in Supplementary Table SI, available at is one study conducted in Japan during the 1980s and Annals of Occupational Hygiene online). Second, clean- published in 2006 that reports manipulation activities ing activities of the MA were uncommon in TRS2, and on brake linings and clutch facings. Instead of trans- old clutch facings and damaged clutch discs were dis- mission mechanics or riveters, these workers were posed on the floor. Thus, asbestos fibers could be re- involved in the reprocessing of automobile brake and suspended, creating an additional source of exposure. clutches (Sakai et al., 2006). Although the occupation Finally, TRS2 was a small shop, with a smaller MA and was different, workers from the Japanese study and the a lower ceiling in comparison to TRS1. Thus, ventila- current study manipulated asbestos containing clutch tion conditions were worst in TRS2. parts, and asbestos exposures of workers sampled in There were two 30-min short-term personal samples both studies are extremely high. Unfortunately, the collected during the manipulation activities of clutch Japanese study only reports PCM concentrations, facings that the riveters reported as asbestos free (i.e. although they used TEM to identify the type of fibers R2 Day3 STlO and Wl Day2 ST2, in Supplementary found (i.e. chrysotile). Table SI, available at Annals of Occupational Hygiene As expected, days with the highest number of online), and no other activity was performed during :; 2- manipulations resulted in the highest 8-h TWA these sampling windows. However, these samples had J PCME personal asbestos concentrations. Focusing asbestos fibers. This phenomenon was also described on the 8-h TWA PCME personal asbestos estimates, in similar studies of brake mechanics in Bogota (Cely- 29% (4 out of 14) exceeded both the us OSHA PEL Garcia et al., 2012, 2014). As it was explained by Cely- us and the Colombian PLVc. Focusing on the PCME Garcia et al., the manipulation equipment may have 30-min short-term personal samples, 4.1 % (2 out of been contaminated with asbestos fibers during previ- :e o o 49) exceeded the OSHA EL. ous manipulation activities, and fibers may have been Q. 'o" The supervisor in TRS 1 (Wl) was the only worker re-suspended. Another potential explanation was that 'Z" sampled who was not exposed to asbestos concentra- although riveters reported clutch facings as asbestos o < (1) tions above the US OSHA or Colombian standards. free, they might have contained asbestos. 3 er This could be explained because this worker rarely Area samples collected in both shops suggest that ~ manipulated clutch facings, and during sampling Days other workers not involved in the manipulation activi- 1 and 3 did not conduct any manipulation activity. ties may be exposed to asbestos fibers. One short-term However, personal samples of Wl indicate exposure area sample collected at 2 m from the manipulation to asbestos fibers. This is important because even at equipment was above the personal sample collected concentrations in compliance with the regulations, on the riveter performing the manipulation. However, there is a risk of developing asbestos-related diseases (OSHA, 1995). Similarly to Wl, other workers and the concentrations of both samples were similar (Personal sample R3 Day2 ST2 = 1.653 f cm-3, area customers that share work areas with riveters may be sample A2 Day2 ST2 =1.715 f cm-3). 1hese samples exposed to asbestos fibers. were collected while the riveter (R3) was cutting the Riveter 3 in TRS2 had two samples that exceeded edges of two clutch facings, and then sanding and the US OSHA EL. R3 also had the highest 8-h TWA grinding them. Because of the location of the door in PCME asbestos concentrations among all work- the TRS (Fig. 1), one potential explanation for this ers sampled, exceeding the US OSHA PEL and result is that the wind may have blown the fibers away Colombian PLVc in 2 of the 5 days sampled. There are from the riveter toward the sampling equipment. Page 14 of 15 Asbestos exposure oftransmission mechanics Workers in shops sampled occaSionally used per- asbestos containing clutch facings because they are sonal protection equipment (PPE) not designed for sold separated from the clutch plate, the lack of train- asbestos protection (i.e. filtering face piece respirators ing on the risks resulting from working with asbes- and clothes). The TRS also lacked adequate ventila- tos-containing products, and the absence of proper tion systems. TRS2 did not have any ventilation sys- engineering controls and PPE, raises serious concerns tem, and the extraction hood ofTRS 1 was operated in about the potential implications that all these factors rare occasions. Moreover, PPE is at the bottom in the may have on the respiratory health of these workers. hierarchy of occupational control options, and other Similarly to what we have found in Colombia, work- alternatives, such as source interventions, should be ers in other low- and middle-income countries may prioritized when trying to reduce the risks of these be experiencing unacceptable occupational risks workers. resulting from asbestos exposure. Thus, it is important From an industrial hygiene perspective, the best to expand our knowledge regarding the risks result- o option to eliminate the risk of asbestos exposure ing from the continuous use of asbestos containing o:;: among transmission mechanics would be to produce products worldwide. The authors recommend that :::> 0- asbestos free clutch facings. Another, less desirable the health} environmental, and labor authorities in 5. "0.. option, would be to commercialize ready to install Colombia should consider requiring, as a transitory 3' asbestos-containing clutch disksj in TRS2 a clutch provision, preassembled asbestos-containing friction :3 disk ready to install was used in one occasion, which products when asbestos-containing products are used. did not require any manipulation. The authors strongly recommend that the production Recognizing that more studies are needed to and use of asbestos-containing products in the coun- improve our understanding of asbestos exposures try should be severely restricted or banned. among mechanics that manipulate asbestos contain- ing products, the results for transmission mechanics observed in the current study suggest that they experience higher exposures than passenger vehicle brake mechanics (Cely-Garcia et al., 2012, 2014). In com- parison to heavy vehicle brake mechanics, asbestos exposures seem to be similar. FUNDING The financial support was provided by the Department of Civil and Environmental Engineering of Universidad de los Andes for the development of this study. The findings of this study confirm the importance ACKNOWLEDGMENTS ~ of being cautious when translating the results of occupational studies from high income to low- and The authors thank Forensic Analytical Laboratories, o 0.. 'o" middle-income countries. The working conditions, Inc.} for the analysis of the samples. The authors also :::> Z characteristics of the products used, tasks performed thank the workers that participated in the study, and the owners of the BRS that gave us permission to con- o < :"3 by workers} workers training} and the enforcement of duct the sampling campaigns on their premises. 0' ~ regulations to protect workers may have major differ- The authors have no conflict-of-interest to declare. ences between countries, even when comparing the same occupations. REFERENCES CONCLUSIONS Although the workers in the TRS sampled reported that the number of clutch facings manipulations has decreased over time, the exposure concentrations found are high. Thus, this group of transmission mechanics is at excess risk of developing asbestosrelated diseases. Furthermore, workers that do not manipulate clutch facings may be exposed to high asbestos concentrations in the workplace. The adverse working conditions ofriveters, the need to manipulate Blake CL, Dotson GS, Harblson RD. (2008) Evaluation of asbestos exposure within the automotive repair industry: a study involving removal of asbestos-containmg body seal ants and drive clutch replacement. Regul Toxicol Pharmacolj 52: 324-3l. Boelter FW, Spencer]\V, Simmons CE. (2007) Heavy equipment maintenance exposure assessment: using a tlme-activ ity model to estimate surrogate values for replacement of missing data. JOccup Environ Hygj 4(7): 525-37. Cely-Garcia MF, SanchezM, Breysse PN et al. (2012) Personal exposures to asbestos fibers during brake maintenance of passenger vehicles. Ann Occup Hygj 56: 985-99. Asbestos exposure of transmission mechanics Page 15 of 15 Cely-Garcia MF, Torres-Duque CA, Duran M et al. (2014) NIOSH. (1994a) Method 7400. Asbestos and other fibers Personal exposure to asbestos and respiratory health of heavy vehicle brake mechanics. JExpo SCI EnvlYon EpldemlOl. by PCM. Manual of analytical methods. 4th edn. Online. Available at http://www.cdc.gov/mosh/docs/2003-1S4/ dOi:1O.l038/jes.2014.8 [Epub ahead ofprintl. pdfs/7400.pdf. Accessed 19 December 2013. Cohen H], Van Orden DR. (2008) Asbestos exposures of NIOSH. (1994b) Method 7402. Asbestos by TEM. Manual of mechanics performing clutch service on motor vehicles. J analytical methods. 4th edn. Onlme. Available at http:// Occup Environ Hyg; 5; 148-56. !ARc. (1998) Asbestos. Summary of data reported and evalua- www.cdc.gov/niosh/docs/2003-1S4/pdfs/7402.pdf. Accessed 19 December 2013. tion. IARC monographs on the evaluation of carcinogenicrisks OMS. (2004) Selected occupatIOnal risk factors. Comparative to humans. IARC monographs on the evaluation of carcino- quantificatIOn of health risks, Vol. 2. Ch. 21. Onhne. genic risks to humans, Volume 14. Online. Available at http:! / Available at http://www.who.int/healthinfo/global_bur- ",'ww.iarc.fr/ en/pubhc.ltlOl1S/hst/ monographs/. Accessed den_disease/era/en/. Accessed 19 December 2013. 19 December 2013. OSHA. (1995) OSHA 3095 (Rev). Asbestos standard for ISO. (1995) ISO 10312. Ambient air. Determination of abes- general industry. Online Available at https:! /www.osha. tos fibres. Direct transfer transmission electron microscopy gov/Publications/osha309S.pdf. Accessed 19 December method. Online. Available at http://wWW.lso.org/iso/cata- 2013. logue_detall.htm?csnumbcr=18358. Accessed 27 May 2014. OSHA. (2008) Personal samphng for air contaminants. ISO. (1999) ISO 13794. Ambient air. Determination of asbes- OSHA technical manual (OTM). SectIOn II: Ch. 1. Online. tos fibres. Indirect-transfer transmission electron microscopy Available at https://www.osha.gov/dts/osta/otm/otm_ll/ method. Online. Available at http://www.lso.org/lso/ otm 11 1.html. Accessed 19 December 2013. catalogue_ detail.htm?csnumber=22933. Accessed 19 OSHA. (2013) Asbestos. Standard number 1910.1 00 1. Onlme. December 2013. Available at https:/ /www.osha.gov/pls/osh:tweb/owadlsp. ]iang GC, Madl AK, Ingmundson K] et al. (2008) A study of show_ document?p_l.lble=STANDARDS&p_ld=999S. airborne chrysotile concentratIOns associated with han- Accessed 19 December 2013. dling, unpackmg, and repackmg boxes ofautomobile clutch Pierce ]S, McKinley MA, Paustenbach DJ. (2008) An evalu- discs. Regul Toxlcol Pharmacol; SI; 87-97. ation of reported no-effect chrysotile asbestos exposures Kanarek MS. (2011) Mesothelioma from chrysotile asbestos: for lung cancer and mesothelioma. Crit Rev Toxicol; 38: update. Ann EpldemlOlj 21 ;688-697. 191-214. Ministerio de Salud y Proteccion Social (MSPS). (2011) Resolucion 007 de 2011 Por la cual se adopta el reglamento Sakai K, Hisanaga N, Shibata E et al. (2006) Asbestos exposures during reprocessing of automobile brakes and clutches. 1nt J de higiene y seguridad del cnsotilo y otms fibras de uso simzlar. Occup Environ Health j 12: 95-105. Bogota, Colombia; Mmisterio de Salud y ProtecClon Social. Thompson SK, Mason E. (2002) Asbestos; mmeral and fibers. NIOSH. (1975) Current Intelligence Bulletm 5; Asbestos Chem Health Sa!; 9; 21-3. ~ 8 exposure during servICing of motor vehicle brake and clutch Yeung P, Patience K, Apthorpe L et al. (1999) An Australian cv: assemblies. Online. Available at http://www.cdc.govI mosh/ study to evaluate worker exposure to chrysotIle in the auto- C :l docs/1970/78127_5.htmI.Accessed 19 December 2013. motive service industry. Appl Occup Environ Hyg; 14: 449-58. o Z < ('l) 3er('l) ~