Document YDjbbGz4rEg1n3zbG5z29aqbN

FILE NAME Brakes BRK DATE 1986 DOC BRK099 DOCUMENT DESCRIPTION Journal Article - Asbestos Dust Exposure During Brake Repair same as 97 s 000422 silica cause lung ! Med 285-294 genkrebsh^/ufigkeit on Health 218-9 Suppl American Journal of Industrial Medicine 10 63 712986 ; Asbestos Dust Exposure During Brake Repair K. R^delspergerPhD H. Jahn ING B. Br^...ckelING J. Manke R. Paur MD and H.-J. Woltowitz Prof Dr Med PhD About 10,000 tons of chrysotile per year are used in the Federal for production of friction Republic of Germany the brake materials During repair an unknown number of By copy and by scanning transmission electron microscopy electron tremely fine chrysotile fibers with lengths < 5 microscopy ex ...mwere identified in brake drum duit Fibers with lengths > 5 ...mconstituted less than % of all 4 brake drum dust Short asbestos dust chrysotile fibers counted in~fl in 101 personal samples during blowing exposures were measured out of brakes and by light microscopy linings During blowing out of car brakes as well grinding and turning of brake the product of fiber concentration with as during grinding of brake linings about 4-5 fibers + min length > 5 ...mand sampling time amounted to min For trucks and buses corresponding to a concentration of 106 fibers over 4-5 . higher amounts of 5-10 106 fibers min were observed during these operations From occupational histories of 210 vehicle average duration of employment of x is is = 21 -10 and mechanics an dose of x -s = 0.54 -1.1 106 fibers years a mean cumulative fiber years were calculated Key words brake repair auto mechanic asbestos occupational history fiber dose exposure light and electron microscopy INTRODUCTION communication The amount of brake lining material used during 1975 in the Federal of Germany was estimated to be 26,000 tons Ullman et al 1978 Republic The asbestos content of brakes used in the FRG ranges from 10-70 weight- with an of 35 weight- Infrared spectographic analysis of 18 samples of brake average material in the following reading of chrysotile Jahn et al 1985 x - = 30 resulted | In accordance with these data it would appear that the asbsestos con-t1e1ntweofigbhratk-e } material increased from 9,000 year in 1975 to about 12,000 year in 1980 and dropped to 10,000 year in 1983 G Schmidt 1984 personal Institute and Polyclinic for Occupational and Social Medicine eral Republic of Germany University Giessen Fed- Address reprint requests to Dr. K. R^delspergerInstitute and Medicine of the University of Giessen Aulweg 129 6300 Polyclinic for Occupational and Social Accepted for publication February 18 1986 Giessen Federal Republic of Germany '1986 Alan R. Liss Inc. EXHIBIT NO Betty Brownino : 4 t iy 64 R^delspergeret al { ! i A large percentage of the approximately 300,000 car mechanics in the F.R.G. . have been exposed to asbestos dust during the cleaning of brake systems and the machining of brake linings It is the aim of this study to estimate the exposure to asbestos dust for this large group of persons Similar to earlier studies on the use of products containing asbestos Heidermanns et al 1978 R^delspergeret al 1980 Woitowitz and R^delsperger1983 a risk assessment is made on the basis of ) dust measurements during brake service 2 screening for fibrogenic reactions by chest rays and 3 evaluation of standardized work histories Our intent is to examine a group of about 400 vehicle mechanics to date 210 have been examined MATERIALS AND METHODS During the maintenance of automobile brake systems 90 dust measurements in 76 garages were taken with static and personal samples In general personal sampling was extended over the whole service operation which lasted 1 h or more but in some cases personal sampling was limited to certain generating work operations Therefore depending on the duration of the work operation sampling time varied from less than 3 min to more than 1 h Fiber concentrations were determined by light and electron microscopy Fibers with lengths > 5 ...mwere counted with phase contrast light microscopy using the reference method of the AIA Asbestos International Association 1979 In addition counts of fibers of lengths 5 5...mand fibers of all lengths were made by scanning transmission electron microscopy at magnifications of 6,300 and 29,000 Since it is suspected that the mineral structure of fibers is altered during the braking process all fibers were examined by energy dispersive ray analysis and electron diffraction In addition to the dust measurements an epidemiological sectional study was planned for a group of 400 car mechanics who have been involved in brake maintenance for at least 10 years A standardized occupational history was adminis- tered to each individual and an extended medical examination made To date 210 occupational histories describing 459 different sets of working conditions under which brake maintenance is carried out have been evaluated RESULTS Working Operations The number of working operations which were registered in 76 automobile garages during dust sampling can be seen in Table I.The use of exhaust ventilation is also indicated Compressed air was used to blow out loose dust in 15 of 36 garages servicing cars and in 19 of 40 garages servicing trucks or buses Special exhaust ventilation systems were used during blowing operations in 8 of the car garages and in 10 of the bus and truck garages In addition to compressed air blowing brushing and the use of solvents were observed Only brake systems heavily contaminated with oil and dirt were cleaned with hot water Fitting of new brake linings for cars was done with special grinding machines in 20 garages Although each grinding machine was combined with an exhaust ventilation none of the filter bags were suitable for asbestos except in 3 garages [- - Ent Ind ce * iss ie rn [Or ee ee mee 8 ms as ee Ot BRO MOS Cre Re ee ~~ ee ae 1 4 GE Y > TES | || L | > ESES ee| Asbestos Dust Exposure During Brake Repair 65 TABLE I. The Number of Work Operations Releasing Dust Observed During Brake Repair in 76 Automobile Maintenance Shops Operation Passenger car n = 36 Blowing out dust Machine grinding of drum brake linings Turning of drum brake linings 15 8 20 20 _ With exhaust ventilation For 17 of these systems the filter bag was not suitable for asbestos Truck bus n = 40 19 10 4 34 11 TABLE II Concentrations of Fibers With Lengths > 5 ...mDetermined by Phase Contrast Microscopy Brake service in automobile repair shops Fiber concentration -10 -10 fibres Passenger ; Truck car bus Operation = 31 n = 36 Blowing out Dry brushing Riveting off and on Grinding by hand Machine grinding Turning Combinations 4 0.10 4 0.05 4 0.09 1 0.15 7 0.10 7 0.12 _ - 5 0.06 1 0.39 - _ 18 0.08 11 0.04 S 0.08 Phase contrast microscopy of fibers with length > 5 ...mPersonal sampling for > 30 min seven measurements were made of personal air samples taken during brake service deviations approximately equal mean values Standard Grinding of brake linings was only done in 4 out of 40 garages servicing trucks and in one of these with exhaust ventilation Thirty garages used a turning machine for fitting brake linings In addition to the stationary machine special movable equipment with arotating cutting tool was used which could be mounted to the axle of the truck Exhaust ventilation was also available for the turning machine in 11 garages servicing trucks In general blowing out and grinding only take a few min for each vehicle On the average the turning of brake linings takes about 30 min per vehicle Concentration of Asbestos Fibers Light microscopy Table II shows the results of 67 measurements of fiber concentrations during personal air sampling of brake repair work for periods of more than 30 min Values are specified for different working operations involving emission of asbestos dust during the maintenance of cars compared with trucks trailers and buses Average fiber concentrations were about 0.1.106 0.1.106 0.1.106 fibers 106 fibers = 1 fiber of lengths > 5 ...mfor all but one of the working operations A concentration of 0.39 106 fibers of lengths > 5 ...mwas reached during machine grinding of brake drum linings in a truck garage The sampling time for this measurement was about 1 h Because of the short duration of dust generation sampling time is about 1 h or less Therefore the average fiber count for all measurements in Table II was only 66 R^delspergeret al TABLE III Concentrations and Doses of Fibers With Lengths > 5 m Brake Service in Automobile Repair Shops Concentration and Fiber Dose" Sampling time t min 153 < 30 30 < < 60 > 60 n - 22 22 Fiber concentration X -) -10 fibers m 5.5 0.47 -0.48 0.09 -0.06 0.08 -0.07 ( -10 fibers m.minm.min 4.8 4.8 4.6 4.9 3.7 -2.5 7.4 5.5 eight fibers per 100 fields Because of this the and the detection limit precision of measurement is very low unused filter corresponds to a count of about one fiber per 100 fields for an ; fibers In Table III 101 measurements with min are compared For all sampling times from < 3 min to 60 considerably as the working operations the average concentration decreased sampling time increased For 14 short sampling time < 3 min the maximum measurements with average reading was 5.5 106 concentration was 20 - 106 fibers The dust emission the fibers Because of the generally short duration of if the average concentration decreased to less than 0.1 106 sampling time exceeded 30 min In addition in Table III fiber is calculated as the concentration is compared with fiber dose which product of concentration and fiber concentration the fiber dose is sampling time In contrast to the fore comparison of the generally independent of sampling time There- emissions of asbestos dust during the different working fibers Table IV specifies fiber doses for fiber times From 40 measurements made lengths > 5 ...mand for all sampling are about 4 106 fibers - during the repair of cars the average fiber doses m min for min for dry brushing and grinding and 5 106 blowing out Generally higher average values are obtained from 46 example they are about 10 106 fiber min The doses can be . >5 compared to the limit value of 1 ...mwhich has been adopted in 106 fibers with lengths in a maximum permissible the Federal Republic of Germany which results Electron dose of 480 - 106 fiber + min for an h shift were microscopy Fibers with lengths of 5 5 counted at a magnification of x6,300 in the ...mon Nucleopore filters microscope In comparison to the results shown in scanning transmission Table IV the dose of chrysotile fibers was considerably higher For instance an was seen in three average reading of 20 106 fibers min measurments made during blowing out of truck drum brakes A TABLE IV I Operation ean Blowing out Dry brushing Riveting off ar Grinding by ha Machine grind Turning Phase contras Brake service equal mean val reading of . ments made Staticmicroscopy microscopy 5...mwer than 1 h..Fil chrysotile r study 1,219 examined by percent of th Other s Heidermanr 1985 Rohl e electron micr 1 weight- braking oper confirmed by few fibers of of dust blow observed at a the crystallin dispersive X- in brake drun 1985 There magnification chrysotile fib Occupation The occ ics had been e of employme Pee Dose se X -s 10 fibers m.min 4.8 4.6 -4.9 3.7 -2.5 7.4 -5.5 amples by phase in the breathing it is very low ) fields for an min to > 60 on decreased rements with pers The duration of vv m dose which ontrast to the time There- rent working r fiber dose a short all sampling e fiber doses 106 fibers ned from 46 rinding for with lengths which results hift ---- filt--e...rs microscope e fibers was m. min n brakes A Asbestos Dust Exposure During Brake Repair 67 me. TABLE IV Dose of Fibers With Lengths > 5 m e Brake service in automobile repair shops fiber dose [ 10"fibres min e Operation Blowing out Dry brushing Riveting off and on Passenger car = 40 S 61301 61301 4.7 4.0 - = 46 Truck bus 8 5.3 1 9.3 Grinding by hand 7 9.0 61301 3.9 - Machine grinding 61301 3.9 Turning 61301 - ~ Combinations - 3.8 - 4 9.9 21 8.6 S 4.4 approximately Phase contrast microscopy of fibers with length > 5 ...mPersonal sampling for < 3 to Brake service was done most commonly for one car or one axis Standard deviations equal mean values 60 min reading of X -s = 35 -45 106 fibers min was obtained in eight measurements made during turning of truck drum linings " Static sampling away from the working operation was also evaluated by electron . microscopy Concentrations of less than 0.03 - 10 asbestos fibers with lengths 5...mwere estimated from these background counts when sampling time was more than 1 h Fiber counting by light microscopy is nonspecific for asbestos Apart from chrysotile metal fibers and other fibers may be released from brake linings In this . study 1,219 fibers with lengths > 5 ...mfrom air samples in repair garages were examined by energy dispersive ray analysis and electron diffraction Seventy percent of these fibers were identified as chrysotile Other studies have been reported on the chrysotile content of brake drum dust Heidermanns et al 1978 Jacko et al 1973 Lorimer et al 1976 R^delspergeret al 1985 Rohl et al 1977 Williams and Muhlbaier 1982 Rohl et al 1976 In several electron microscopic studies brake drum dust showed an asbestos content of less than 1 weight- indicating a partial physical breakdown of chrysotile fibers during the braking operation leading to a large number of short thin fibers These results are confirmed by our study As shown in Figure 1 at a magnification of 6,300 only a few fibers of lengths 5 5...mare seen After air sampling on Nucleopore filters of dust blown from brake drums numerous fibers usually of lengths < 2 were m observed at a magnification of x35,000 x50,000 and x60,000 Since alteration of the crystalline structure of these fibrils is possible electron diffraction and dispersive ray analysis were also done It was found that the thin fibers energy in brake drum dust did not differ from fibrils of observed chrysotile R^delspergeret al 1985 Therefore in brake drum dust even under electron microscopy evaluation at a magnification of x6,300 chrysotile fibers of lengths 5 5...monly form % / of chrysotile fibers of all lengths measured at a magnification of 29,000 Occupational Histories The occupational histories of 210 car mechanics were evaluated These mechan- ics had been engaged in brake maintenance for at least 10 The of employment as a car mechanic was X - = 21 years average duration -10 years ee aye Eta! . uz FY Fig 1. Asbestos fibers in brake drum dust Scanning transmission electron microscopy at different magnifications Upper left x6,300 upper right 35,000 lower left ^ 50,000 lower right 60,000 Whereas at a magnification of x6,300 lower borderline = 14 monly a few fibers are visible at higher magnifications numerous unit fibrils are observed Si 459 job they ha generat T work a type of of the j these ca brakes work 7 all othe M type of 83 c drum b trucks ' buses mainly been us F dust ex dose va car Di describ cars re fiber do account year as T. fibers v was no The me mechan TABLE Dust Brake rep Passenge Truck b Other ve Clutch re Percent exposed t opy at different right x60,000 s are visible at Asbestos Dust Exposure During Brake Repair 69 Since most of the mechanics had more than one employment position altogether 459 job profiles were described Nine car mechanics gave descriptions of jobs where they had not repaired brakes themselves but had been exposed to asbestos dust generated by others Table V shows the percentage of job profiles that involved brake maintenance work and the number of vehicles with brake repairs per week classified according to type of vehicle The average number of clutch repairs per year is also shown In 60 of the job profiles mechanics repaired car brakes averaging 4.6 jobs per week In these cases the duration of repair work was approximately 2 h On average the brakes of trucks or buses were repaired 2.6 times per week by those who did such work The average duration was approximately 4 h The duration was about 2 h for all other vehicles e.g. fork trucks Clutch repair also took an average of 2 h Mechanic work activities during brake and clutch repair specified according to type of vehicle are shown in Table VI In almost all repairs either blowing out 75- 83 or dry brushing 54-59 of drum brakes took place Machine grinding of drum brakes is described in 25-36 and grinding by hand in 55-75 of the jobs for trucks buses and cars whereas turning 6-6%4 was mainly restricted to trucks and buses The cutting and drilling of brake linings reported in 11-26 of the jobs mainly occurred before 1960. Since then precut and predrilled brake linings have been used . dust From dust measurements exposures expressed as a and occupational histories cumulative fiber dose can as be follows shown in Tables A calculated as follows dose value as shown in Table VI is equivalent to the dose for the maintenance of one car Dose values per car can be calculated if the frequency of work operations described in Tables IV and VI are known for a particular job Taking the number of cars repaired per year Table V and the duration of employment the cumulative fiber dose per job can be calculated All jobs of the car mechanics are taken into account The unit of measurement fibers min is converted into fibers . year assuming 240 working shifts per year each of 480 min duration The cumulative probability distribution function of cumulative fiber dose for fibers with lengths > 5 ...mis shown in Figure 2. For % of the 210 workers there was no measurable fiber dose since they were only indirectly exposed as bystanders The median value is 0.3 106 fibers years for about % of the vehicle mechanics the cumulative fiber dose exceeds 1.106 1.106 1.106 fibers years Thus the TABLE V. Occupational Histories of 210 Vehicle Mechanics With Potential Exposure to Abestos Dust Brake repair No. of employment histories reporting brake or clutch repair work by vehicle n % vehicles vehicles rerpeapiarieredd per week - Passenger car Truck bus Other vehicles Clutch repair 275 J28 4.6 -4.6 209 J28 2.6 -3.9 32 J28 3.7 -5.0 278 61 1.8 -2.0 Percentage of 459 employment histories of 210 vehicle mechanics In 33 histories mechanics were exposed only as bystanders 70 R^delspergeret al TDuAsBtLE VI Occupational History of 210 Vehicle Mechanics With Potential Exposure to Abestos Operation Blowing out Dry brushing Riveting off and on Grinding by hand Machine Passenger cars 198 76 59 86 75 Trucks buses No. of jobs = 100 133 Percentage ofjob profiles that involved indicated operation 75 54 93 56 Mixed 78 58 58 87 55 grinding Turning Cutting and 26 23 ' 26 64 drilling 14 11 26 buses Four hundred nine jobs of 210 car mechanics In 50 other repairs of passenger cars trucks or jobs the mechanics did not perform brake % distrbuion Cumlative iT T is T T T T T T T 4 25 .5 l 1.5 2 3 Fibre dose length > 5...m [ 105 fibres * years is Fig 2. Exposure of 210 vehicle mechanics during brake maintenance bution function of cumulative fiber dose for fibers with Cumulative probability distri- exposure is less than 3 - 106 fibers lengths > 5 ...mFor 99 of all mechanics fibers years are calculated years For two further mechanics % doses of 7 and 13 10" average value amounts to X 1 s = 0.54 -1.1 106 fibers corresponds to an exposure of about 6 months with years This 1 106 fibers with an asbestos fiber concentration of lengths of > 5 m In 1981 Nicholson et al estimated about 350 asbestos te afimboerng car mechanics for the United States This number wacsanbcaesreddeoanthasnper year average exposure level of 0.1 to 0.3 106 fibers Compared to our results of average dose of 0.54 106 fibers an years during an average period of 21 years that c tion e brake CON low fi fiber Blowi less th Conce sampl fibers fibers micro fiber uncert tained data i the cu to the been c roofer and R~ exposi m wit and pr has bee been ir out and are cal ACKN Project REFER Asbestos as e to Abestos Mixed 78 d 8 $ ___ 87 55 36 42 , 26 I perform brake 3 3 -s i robability distri- f all mechanics o of 7fand 13 106 This years This ncentration of aths per year an average results of an 1 of 21 years Asbestos Dust Exposure During Brake Repair 71 that concentration estimate seems to be at least four times higher than the concentra- tion estimated in our study Four cases of mesothelioma have been observed among brake repair workers seen as patients in our Polyclinic Paur et al 1985 CONCLUSIONS Asbestos dust measurements in garages during brake service operations show low fiber concentrations typically about 0.1 106 fibers average and also low fiber doses The working conditions are generally characterized by short exposure Blowing out and machine grinding take only min and the time taken for turning is less than 1 h per vehicle All results are considerably below the existing German Technical Guiding Concentration TRK of 1 106 fibers with lengths > 5 ...mwhen a minimum sampling time of 1 h is taken Electron microscopy of brake drum dust does not indicate a high occurrence of fibers with lengths > 5 ...mhowever there are very high concentrations of short fibers Mass concentration of asbestos estimated from scanning transmission electron microscopy indicates the mass of fibers as < 1 weight- R^delspergeret al 1985 Fiber concentrations for certain working operations are characterized by low fiber counts and therefore by a high uncertainty factor Furthermore there is a high uncertainty in the knowledge of the frequency of different working operations obtained using a standardized occupational history However the inconsistency in these ' data inasmuch as it is measurable has no great influence on the calculated size of the cumulative fiber dose The data also allow the ranking of the workers according to the severity of exposure An average value of a cumulative fiber dose of 0.54 - 106 fibers years has been obtained This dose is one order of magnitude lower than an estimate made for roofers cutting asbestos cement at building sites R^delspergeret al 1980 Woitowitz and R^delsperger1983 It is about one order of magnitude above the environmental exposure which in the Federal Republic of Germany is usually less than 1,000 fibers m with lengths > 5 m Some changes in working conditions have taken place Nowadays only precut and predrilled brake linings are used Machine grinding is less frequent for cars and has been replaced by turning in the case of trucks and buses Exhaust ventilation has been introduced almost universally during grinding and to some extent during blowing out and turning These changes have to be mentioned when cumulative dose values are calculated from results of dust measurements and occupational history . ; ACKNOWLEDGMENT Project Supported by the German Federal Ministry for Science and Technology Bonn Project No. 01 VD 2900 REFERENCES Asbestos International Association AIA 1979 Reference method for the determination of airborne asbestos fibre concentrations at workplaces by light microscopy Membrane filter method London . 72 R^delspergeret al Hauptverband der gewerblichen Berufsgenossenschaften e.V. ed Heidermanns F K^...hnen A Prochazka R Riediger G Woitowitz H Valentin H Henke R Woitowitz G Sch^...tz KP Klosterk^tterW Bruch J 1978 Untersuchungen ^...berdie GesundheitsgefahrRenHduHroclhzShatu^s/eurbe asbesthaltiger Bremsbel^/geForschungsbericht Asbest Bonn Schriftenreihe des der gewerblichen Berufsgenossenschaften V. Hauptverbandes Asbeststaubgef^/hrdung Jahn H R^delsperger K Br^...ckel B Manke J Woitowitz H Bremsendiensten.Staub Luft 1985 in Jacko MG DuCharme RT Somers JH 80 83 operation Automobile 1973 Brake and clutch emissions generated during vehicle Lorimer engineering meeting Detroit Michigan May 14-18 pp 1-20 WV Rohl AN Miller A Nicholson WJ Selikoff U 1976 Asbestos workers in the United States Mount Sinai J Med 207-218 exposure of brake repair Nicholson WJ Perkel G Selikoff U 1981 Cancer from 1980 2000In R. Peto M. Schneidermann occupational asbestos exposure projections Spring Harbor Laboratory pp 87-111 Eds Banbury Report No. 9. New York Cold Paur R. Woitowitz H R^delspergerK Jahn H ( 1985 Pleuramesotheliom nach 3be6i6Bremsreparaturen im Handwerk Kasuistische Beobachtungen PArsabxesPtsnteauumboglef3^/6hr2du-ng R^delspergerK Woitowitz H Krieger HG 1980 Estimation of building sites Biological effects of Mineral Fibres Vol 2 Je.xC.poWsuargenteoraLsyboneSsctioesntdiusftiocn Publications No. 30 pp 845-853 . R^delspergerK Br^...ckelB Jahn H Manke J Woitowitz H 1985 Asbestemission bei gen Reinhalt Luft 26-31 Bremsvorg^/n- Rohl AN Langer AM Klimentidis R Wolff MS Selikoff U tered in brake maintenance and repair Proc Roy Soc Me1d93727-A3sb7estos content of dust encoun- Rohl AN Langer AM Wolff MS Weisman I 1976 Asbestos repair Environ Res 110-128 exposure during brake maintenance and Ullmann D. Eggersdorfer R K^nigR 1978 Analyse der . Asbestindustrie im Auftrag des Umweltbundesamtes Bericht Bericht des Instituts Williams RL Muhlbaier JL ( 1982 Asbestos brake 4/78 Berlin Erich Schmidt Woitowitz H R^delspergerK 1983 emissions Gesundheitsrisiko Environ Res 70-82 Berichte 313 324 bei der Anwendung asbesthaltiger Produkte Patt Kenne ARRED<PZ^ S AR ED<PZ^ S AR ED<PZ^ S ARRED<PZ^ S ARRED<PZ^ S AR ED<PZ^ S ^ " 522 522 522 Key wor INTRO Pl asbestos used to resident exposed Th Pipe Fi represe concern about th mortalit years 19 local un Environm Address 1 Cancer In Accepted '1986: