Document bX6RXgkvMB707mXYwB03Vy3Z

FILE NAME Brakes BRK DATE 1987 Aug DOC BRK159 DOCUMENT DESCRIPTION NIOSH Report - Evaluation of Brake Drum Service Controls Possibly Same as 158 THE E 16 001 : 2001 PB. * .* . GQ -~ DEPTH SURVEY REPORT EVALUATION OF BRAKE DRUM SERVICE CONTROLS AT United States Postal Service Vehicle Maintenance Facility Nashville Tennessee REPORT WRITTEN BY Frank W. Godbey Thomas C. Cooper John W. Sheehy Ph.D. DenniMs. O'Brien Ph.D. Harold D. Van Wagenen James D. McGlothlin _ William F. Todd REPORT DATE August 1987 REPORT NO ECTB 152-20b NATIONAL INSTITUTE FOR OCCUPATIONAL SAFETY AND HEALTH Division of Physical Sciences and Engineering Engineering Control Technology Branch 4676 Columbia Parkway Cincinnati Ohio 45226 Tue tet Veo Gkrute py lang rm PLANT SURVEYED SIC CODE SURVEY DATE SURVEY CONDUCTED BY EMPLOYER REPRESENTATIVES CONTACTED EMPLOYEE REPRESENTATIVES CONTACTED ANALYTICAL WORK PERFORMED BY United States Postal Service Vehicle Maintenance 707 Chestnut Street Facility Nashville Tennessee 37203 4311 October 27-30 1986 Frank W. Godbey Thomas C. Cooper Harold D. Van Wagenen Dennis M. O'Brien Charles Harvey Fleet Operations Manager 742-0207 Robert Hart Supervisor Vehicle Maintenance 742-0203 James C. Hollingsworth Nashville Local American Postal Workers Chief Steward Union AFL Eugenia Shtrom PE1 and formerly Utah Biomedical Laboratory Data Chem Testing 3N THE : ist g I. INTRODUCTION The National Institute for Occupational Safety and Health NIOSH is the primary Federal agency engaged in occupational safety and health research Located in the Department of Health and Human Services formerly Department of Health Education and Wolfare it was octabliched by the Occupational and Health Act of 1970. This legislation mandated Safety NIOSH to conduct a number of research and education programs separate from the standard setting and enforcement functions of the Occupational Safety and Health Administration OSHA in the Department of Labor An important area of NIOSH with method for research deal cnuteolling vocupational Capusure to potential chemical and physical hazards to safe levels The Engineering Control Technology Branch ECTB of the Division of Physical Sciences and Engineering has been given the lead within NIOSH to study the engineering aspects of hazard control Since 1976 ECTB has conducted a number of assessments of health hazard control technology on the basis of industry common industrial process or specific control techniques Examples of these completed studies include the foundry industry various chemical manufacturing or processing operations spray painting and the recirculation of exhaust air The objective of each of these studies has been to evaluate and document effective control techniques for potential health hazards in the industry interest and to create a more general awareness of the or process of need for or availability of an effective system of hazard control measures These ctudies involve surveys are conducted a number of phacoc to select plants or Initially a oorioc of walk processes with effective and through potentially surveys are transferable conducted to control concepts or techniques Next depth determine both the control parameters and the effectiveness of these controls The reports from these then used ac a basis for preparing technical reports and depth surveys journal articles are on effective hazard control measures Ultimately the information from these research activities builds the data base of publicly available information on hazard control for preventing techniques for use by health professionals occupational illness and injury who are responsible Background Asbestos is found in motor vehicle brake materials Recognition of asbestos carcinogenic properties has currently resulted in substitution of less toxic fibers for come brake materials However acbertor in still used in number of brakes large This study is concerned with the control of asbestos exposures to workers who are required to repair motor vehicle brakes Dubrow and Wegman published a research and control priority assessment of occupational carcinogens Their objective was to identify occupations with potentially high cancer risk by combining the results of 12 major Occupational disease surveillance studies and to make recommendations concerning priorities for occupational cancer research and control on the basis of the results of this analysis in conjunction with other available epidemiologic industrial hygiene toxicologic and employment data basis of the principles outlined in their paper some priorities for On the research Un dae t 3 : 11 RlOS and control clearly stood out Their results pointed to the investigation control of occupational exposure to asbestos as the number one priority in and occupational cancer research and control In this situation where occupational disease surveillance studies point to a likely problem with a known carcinogenic agent the priority should be placed on industrial hygiene investigations of asbestos exposure in the suspect occupations If likely exposure is found control measures should be developed and instituted There are frequent asbestos exposures during brake repair in the vehicle maintenance work force NIOSH in the National Occupational Exposure Survey estimates that a work force of 151,000 brake mechanics and garage workers in the U.S. are potentially exposed to asbestos Other estimates run as high as 900,000 workers being potentially exposed in brake servicin3g A study of brake service operations was needed because of the following known carcinogenic potential of asbestos a large number of workers are the potentially exposed primarily small businesses lack resources to evaluate control devices and perform brake servicing the general lack of and information on the effectiveness of currently available control devices Therefore the Engineering Control Technology Branch undertook this study The primary objective of this control technology assessment is to determine the the effectiveness of various control techniques used during brake repair transfer of the documented information to the appropriate individuals and in industry labor academia and the government i.e. industrial hygienists safety engineers OSHA EPA etc. A secondary objective of this assessment is to determine if additional research is needed Description of Brake Servicing Operations Repair facilities follow the same basic servicing procedures The vehicle is driven into a repair stall or bay for a brake system examination Pending repairs the wheels are elevated removed and the brakes inspected Loose dust is cleaned from the drums and brake assemblies by vacuuming wet or dry brushing using compressed air or a combination of these methods Parts are then replaced or repaired as needed and the brake system is reassembled and adjusted The vehicle is then driven to check and adjustment in the final phase of the servicing operation for proper fit The brake repairman and other service personnel potentially exposed to asbestos dust during and removal If the normal dust buildup inside the removed and disposed of in a controlled manner in the garage area are following the brake drum drum and brake assembly is this hazard can be minimized Site Selection Preliminary techniques surveys were conducted at 10 sites using a variety of control These site visits were conducted to observe the control techniques in were selected vehicle type use and to select sites for detailed sampling studies Sites primarily from fleet garages to control for variables such as use and maintenance practice and on the physical size of the garage criteria Selection of including sites was made as judiciously as possible based on 7 } ea bee na 1 0 | re . a The type of control technique being used at that site b The type and quantity of vehicles available for brake repair Good work practices and a sound management approach were fundamental to the existence of suitable conditions for study Health Effects The health significance of the inhalation of chrysotile asbestos fibers in auto In a repair workers includes detailed examination of asbestosis lung cancer and mesothelio 4m -a 8 90 union motor vehicle maintenance workore in Now York City with 10 or more years of shop work 29 had decreased vital capacity the percentage increased from the onset of auto work many with age and most markedly after 20 years of the workers examined showed signs consistent with asbestosis with observed changes noted in chest rays and indication of restrictive pulmonary function The prevalence of these changes was significantly higher after 20 years exposure a result expected after occupational exposure to asbesto8s Many of the asbestos fibers originally present in the unused brake shoe chemically degrade due to the high temperature asbestos fibers exist in automobile brake dust encountered in use in various states of Chrysotile deformation Unlike chrysotile the health effects of exposure to forsterite a deformation product of chrysotile or to transition series fibers chrysotile with altered crystalline structures are not well documented In studies by Davis and Coniam and Koshi in which fibers of chrysotile forsterite and forsterite were injected into the pleural and peritoneal cavities of mice the results suggested varying dogroco of toxic ottocts Fibor implantation animal studios conducted by Pott et 11,12 and Davis et al 13 suggest that the and size of a fiber regardless of fiber type are responsible morphology for its carcinogenicity Likewise Stanton et 14 suggests that fibers less than 1.5 um in diameter and greater than 8 um in producing pleural sarcomas These studies in length pose the greatest tend to suggest that the risk physical morphology size dimensions and to a lesser degree chemical and surface characteristics biological effect The of a fiber are the determining factors for inducing a precise fiber dimensional characteristics required for these observed pathologic responses have been difficult to determine experimentally because of the difficulties encountered in producing fibers of specific size dimensions Because of the observed health effects in auto repair a clearly identified effect level for asbestos it exposure to brake dust which may contain asbestos workers and the is important to lack of minimize The two sources of occpuational exposure are 1 the NIOSH Recommended Exposure of Labor OSHA Permissible Exposure Limit criteria considered in this study Limit REL and 2 the Department PEL NIOSH recommends that employee exposure feasible limit due to the carcinogenic to asbestos be nature of this reduced to substance the lowest The NIOSH 11 31 31 cone a REL published in 1976 is centimeter cc 15 0.1 fibers greater than 5 m in length per cubic NIOSH submitted an update on the recommended asbestos criteria at proposed making hearings for asbestos in June 1984. The position is summarized below the OSHA NIOSH The carcinogenic potential of asbestos is no longer in doubt however there is some uncertainly shout the toxicaingical and morphological properties which determine the carcinogenic potency of various fibers NIOSH believes that on the basis of available information there is no scientific basis for differentiating between asbestos fiber types for regulatory purposes Data available to date provide no evidence for the existence of a threshold level studied to date demonstrated an Virtually all levels of asbestos exposure excess of asbestos disease NIOSH continues to believe that both asbestos and smoking are independently capable of increasing the risk of lung cancer mortality When exposure to both occurs the combined effect with respect to lung cancer appears to be multiplicative rather than additive From the evidence presented we of causing lung cancer may and conclude that mesothelioma asbestos is independent a carcinogen of smoking capable NIOSH has recommended that asbestos be controlled to the lowest detectable limit It is our contention that there is no safe concentration of axposure will not to asbestos Any standard no ensure absolute protection for matter how low the concentration all workers from developing cancer as a result their occupational exposure However lower exposur~ sexposur~ s carry lower risks Tann Since the only widely wwallable method NIOSH Mathod 17 is to achieve intralaboratory accuracy of 12.8 RSD at an exposure able limit of 0.1 cc 100,000 min a 400 liter sample NIOSH and others have recommended an exposure limit REL of 0.1 cc for asbestos based on hour weighted average concentrations While this is a well undorctood practico wo can not find compolling argumente to prevent a recommendation based on alternative sampling periods In fact such an approach may provide more protection than an hour based sampling period that allows short exposures 6 or 10 times greater than the hour exposure limito being considered by O HA Furthermore since there is uncertainty rogarding the cumulativo doco roquirod to initiato dicoaco it seems reasonable to make overy attempt to control exposures to as narrow a range of restrict concentrations as possible One way to accomplish the period over which workplace concentrations can this is to be averaged Perconal campling pumps are available with flow ratac up to 3.5 1pm which would allow a campling time of two houre or lost Finally we still believe that there are occasions such as mixed fiber exposures where fiber specificity is necessary Therefore we recommend the use of electron microscopy in the event of process or product modification in mixed fiber exposures or when there are other reasons for characterization of fiber type and morphology 4 Vids P Se It 34 . 38 1 . CHEE As noted the occupational exposure criteria - the NIOSH REL and the OSHA PEL- are method based on the readily available Phase This method has inherent limitations Contrast based on Microscopy analytical the physics of the optical microscope and upon the ability of discriminate the specified length to width The minimum diameter routinely observed is the counters to reliably ratin in a complex sample matrix on the order of O. ...m The NIOSH 7400 method stipulates that only fibers longer than 5 um be counted with a length to width ratio of either 1 A rules or 1 B rules The A rules use the have the advantage of same aspect relating to ratio as the current OSHA standard and current and historical compliance data thus They have the potential disadvantage of counting particles that may or may not be fibers In the present study TEM offers the advantage of being able to determine the actual dimensions of all fibers that were counted and thus to dillerentiate the numbers of fibers will various lenglis to width ratios A coarse analysis of this data indicates and 7400 counting rules would differ that fiber counts by less than 15 using NIOSH A 7400. Another concern is that asbestos fibrils as small as 0.02 ...m in diameter and less than 1 ...min length are visible only with electron microscopy These fibrils constitute a significant and variable proportion of the total fibers present in brake dust Thus PCM in counting only optically visible particles may not be a good indicator of the total fibers present Controversy over the health affect of small fibara and thus what sizes of Fibers should he mounted adds further ambiguity to this area On June 20 1986 OSHA issued a revised standard PEL which reduced the PCM level to 0.3 00 00 on 8 hour timo uoightod average TWA onpoques It aloo set an action level of 0.1 cc that triggers worker training medical monitoring monitoring and other requirements or short exposure limit The new standard dues not sel a ceiling Facility Description II PLANT AND PROCESS DESCRIPTION ' The United States Post Office Maintenance Garage in Nashville services all the Federal postal vehicles for the Sectional Center District of Tennessee This involves 575 vehicles whose city routes cover nearly half of the state Records on all these Postal vehicles are kept by computer Each year each vehicle has a minimum of two complete inspections If the computer record shows more than 500 miles per month usage then the yearly scheduled inspections are increased from 2 to 3. An average city mail delivery route is within a 20-30 mile range with a minimum of 250-400 mail stops The local Postmaster keeps track of vehicle mileage and may shift vehicles from route to route same so that total vehicle mileage on all routes stay approximately the All the garage shop personnel are members of the American Postal Workers Union CIO In the entire Sectional Center District facility services the following the Nashville vehicle maintenance 5 1 Five hundred and seventy Jeep delivery vehicles - This category includes 1/4 and 1/2 ton special vehicles Jeep engines and chassis but a larger enclosure than the standard Jeep delivery unit Eighty to 85 of the the 575 vehicles are the AM General remainder are special vehicles Post Office delivery vehicle type and Most of the delivery cylinder engines - Jeeps and all the remainder the 1/4 and 1/2 have cylinder Ton units engines have Most of the delivery Jeeps have 13 or 14 wheels and 10 long brake shoes Jeep delivery vehicles have the following specifications a Manufacturer - AM General formerly American Motors Corporation b Model c Model year - 1973 to 1986 d Brake Type - All four wheels equipped with drum brakes e Tires - Bias Ply f Vehicle Weight - 2,310 pounds 8 Transmission - Automatic h Differential - limited slip rear wheel drive 2 Thirteen seven International trucks disc brakes all four wheels 3 Three Mack and two White tractors drum brakes all four wheels 4 Seven trailers The one garage is staffed with nine mechanics one lead mechanic four garagemen body man and two supervisors Six mechanics work from 6:00 am to 2:30 p.m. and four mechanics work from 9:30 a.m. tu 6:00 p.m. with all 10 mechanics on duty from 9:30 a.m. to 2:30 p.m. The garage building sides working area of 64 by ill race feet East and west and a ceiling and is height 202 feet long with of 20 feet There a die seven bay doors on each side feet wide plan of the with each door approximately feet high and working area it shown in Figure 1. When the garage was Bloutviool opened in 1979-80 building heat was provided by a bank of six hostore oquipped with small fans anapended in a row on each side of the garage 12 heaters Because these units were expensive to operate they are no longer used installed at each corner In their place of the garage four fired unit heaters were There Thasa is an under hose and pipe are located in the floor by the system to remove auto doore of the 14 baya exhaust Six of fumes the hays Tum fe ES it 00 os . 2011 Ju are equipped with hydraulic lifts both front and rear of each they can work on twelve elevated vehicles at the same time vohicle so Each bay has a working width of 13 feel Numerous electrical cables ure suspended from above alongside the bay These are extended for use to power the numerous power tools the mechanics use Much of the repair work is done with the mechanic standing under the elevated vehicle Ventilation of the garage is minimal There is a series of mounted fans on each side of the from under the roof garage These are operated in summer to remove hot air area In the cooler months these fans are not used and the inlet dampers are kept closed There is no provision for heated air from the outside When the 14 providing fresh mild bay doors can be left open during weather they provide a lot of useful ventilation During colder weather the garage air temperature is kept at 60-65 at the mechanics working level Process and Equipment Description This facility is currently replacing asbestos brake shoes with the nonasbestos type when venicle brakes are repaired our control evaluation at this facility concentrated on Jeep vehicle maintenance to determine the of control effectiveness in the variability same model vehicle during 10 separate vehicle brake repair or inspections A 760 brake wacher accembly unit Kloer Flo Model LW 22 Rollabout had been used to control potential asbestos exposure at this facility for several months prior to our survey Figure 2 shows this washer unit Although the unil was not evaluated in use on any type of vehicles except jeeps supervision reported good results when using this unit on the larger vehicles ac wall Tho portablo washer mover easily to the brake repair location A. water solution GreasofffiNo. 19 recirculates through a flexible tube and brush to flood parts clean The upper tray raises to the work area to hold small parts ready for reassembly and to catch the solution A pump in this machine pulls the solution through a nylon filter and then pumps the filtered solution through a flexible tube and out between the bristles of the brush allowing a gentle flooding of the brake assembly area to wash down dust and perform the any necessary cleaning The solution is returned to the bottom tank where the bottom it is recirculated tank for The upper tray is removable to permit use of cleaning brakes on larger vehicles One gallon of Greasoff No. 19 a liquid concentrate mixed with five gallons of water and is used to clean 40 to 50 wheels before it needs to be dicearded Four gallons of Groacoff No. 19 co t 75 GreasofffiNo. 19 contains the following hazardous ingredients less than % by weight sodium metasilicate a highly alkaline compound pH 12.4 and less than % by weight ethylene glycol monobutyl ether which is also known as its butoxy ethanol or by common name of butyl Cellosolve Sodium metasilicate is Beverly irritating to the eyes skin and mucus membranes Ethylene glycol monobutyl ether or butoxy ethanol is absorbed by the skin and is a The current OSHA standard for hemolytic agent butoxy ethanol is 50 ppm The 1981 Threshold Limit Value TLV listed in the American Conference of Govermental Industrial Hygienist ACGIH booklet reduced the TLV to 25 ppm Wearing of goggles or TR Pht ds 1 e. tt wreg MAINTENANCE MAINTENACE doug 23 (+9 8 sdoysg X SOVYD Shop Area 00 Batery 14 Bays 8 t Tuol 202) g + & 8 vely x doys (ut (sfg 420m x Work arog #9) og #71) at pug 986T a8eie9 Sasn Jo L L ^' DONYGLIVN J OFICEPOST OFFICE |, TENNESSEE TENNESSEE anipg ie PlPOaSnT CO fue * fh ofertas SU (x3mo0d) 370NtH nHe us ay493 / |9a205) 694579 yIsVs JI9KS NMeOUSeavnt! ARAM T+9ONawcd WZAIMS gy YIOM 33oH AD CORD SHELF DATA PUMP / wsAye - se L ~~ ~~ oN.>L 12eysen ~SUILSY axBIA PUMP AY 2indta | | A0) NISVS AVIHS Washer NAOM ; lite ret 16 11:10:12 11:10:12 2000 13 side shield recommended safety glasses for preventing and rubber or chemical resistant clothing is skin contact when handling Greasoff /No. 19 The washer unit has a gallon capacity During our survey this facility disposed of the used liquid on a monthly basis Approximately 25 brake jobs were performed each month with the liquid being changed after each 10 to 12 brake jobs The ten gallons of used brake cleaner is placed in sealed gallon cans and marked in accordance with EPA instructions for disposal An approved contractor picks up the used liquid and disposes of it in an approved toxic waste site Some of the features of the brake washer assembly include 1 A gentle flow of solvent to the workshelf basin area to wel the back plate and brake components in order to avoid spreading dust into the air and at the same time clean the components spillage 2 A low center of gravity to avoid tipping and may contain asbestos fibers of solution which 3 An adjustable work tray allowing the mechanic to position the tray at a height to avoid splashing and spillage 4 A design that can be used on both automobiles and trucks so the mechanic can maintain safe work practices for all types of vehicles A reservoir equipped with a removable cover to when covered and as a work tray when the cover large vehicles prevent liquid is removed for evaporation work on The manufacturer recommends the following sequence for use of their unit for brake shoe servicing 1 Fill the reservoir with one gallon of brake cleaner concentrate and five gallons of water 2 Make sure the switch is in OFF position and plug into power source 3 Make sure the bruch is positioned toward the solvent supply or in the catch basin to prevent accidental spillage and loss of solution Do not leave brush and hose assembly on the floor 4 If the vehicle is on a lift place the machine so that the catch basin is directly under the brake assembly Height of the catch basin can be adjusted for convenience of the mechanic If the vehicle is raised by a front lift or jack as is often the case with trucks cleaning can be done by removing the catch basin opening the hinged cover of the main reservoir tank and cleaning over the expanded metal mesh covering the fluid reservoir 10 11+ ae IN 14.1 14.1 13 201 P. 14 5 Turn the switch ON and the fluid will be pumped through the brush hose assembly and cleaning can commence Regulation of the fluid flow is controlled by a valve at the pump connection 6 The Thru brush provides a wetting action to wash away dust asbestos fibers oil and grease Small parts can be conveniently cleaned and stored in the catch basin or in the main tank 7 Fluid should be disposed of in accordance with local state and federal requirements The barrier filter should be washed at this time The mechanics worked confidently with this brake washer believed it did a good job of containing and collecting employed on any size vehicle assembly unit and brake dust when III METHODOLOGY Air Sampling and Analysis Personal air samples for asbestos were collected in duplicate on 0.8 pore size 25 diameter cellulose ester membrane filters at 3.0 1pm for the duration of a single brake job or 2 hours whichever was longer The total volume collected 360 liters allowed a limit of detection of approximately 0.004 fibers by Phase Contrast Microscopy PCM analysis Area air samples for asbestos were collected on cellulose ester filters Two area samples were collected at the vehicle fender and the axle source samples at approximately 7.0 1pm for the duration of a single brake job or 2 hours whichever was longer The source samples escaping into the working environment during the were used cleansing to measure and repair fibers activity The minimum volume collected 840 liters allowed a limit of detection of 0.002 fibers by PCM Two additional collected in the general garage area background at a hour period encompassing pre- and brake job area samples were approximately 7.0 1pm activities These for background samples were and overall containment used to determine effects of general shop cleanliness effectiveness of the controls The minimum volume collected 1,680 liters allowed a limit of detection of 0.001 Fibers Two other area samples were collected out of doors several hundred feet from the Building Building at 301 301 Con a App~ uzimate App~ uzimate li prvisul prvisul These ambient ambient samples samples were used to determine unvironmental levels of asbestos The minimum volume collected 1,440 liters allowed a limit of detection of 0.001 fibers All filter air samples were analyzed by Phase Contrast Microscopy PCM in accordance with NIOSH Method 7400. In addition to PCM analysis approximately 2/3 of these samples were analyzed by field Transmission Electron Microscopy TEM To facilitate analysis by PCM and TEM on the same samples the and Rood direct transfer method of sample was used For PCM analysis all preparation fibers with described a 1 or by Burdett greater ratio were counted using Method 7400B counting rules TEM analysis of these samples show that more than 85 of the chrysotile fibers counted using the A rules would also have been counted using the B rules For TEM analysis 11 fi" fi efi efl 16 10-1110-11 29BLE 19 fiber type and size distribution were obtained for all fibers greater than approximately 0.25 um diameter using a magnification of 17,600X and counting either a minimum of 10 grids or 100 particles whichever came first Bulk Samples and Rafter Sample Field blanks were prepared for each sampling date TEM analysis Twelve blanks were analyzed by PCM these results are shown in Table 1 of Appendix A. show all blanks were below detectable limits and submitted for PCM and and 6 blanks Analycic by by TEM and PCM and TEM A bulk brake dust samples for each vehicle and a bulk rafter sample for the site were collected and analyzed for asbestos by TEM The percentage of asbestos in the bulk samples was qualitatively determined by estimating the ratio of the number of asbestos fibers to total dust particles The percentage length and of fibers that were asbestos was quantitatively determined the diameter of asbestos and other fibers were measured Elemental analysis of the nonasbestiform constituents was performed using energy dispersive ray analysis Real Monitoring The entire brake maintenance operation was recorded on videotape Two Hand Aerosol Monitors HAMS ppm Inc. Knoxville Tennessee and a personal computer Apple II Plus were used to measure and record the dust levels The HAM's electro system provides instantaneous measurements of total dust levels in mat one second intervals The HAM sends a millivolt signal to the computer which records it as a relative dust level The computer program can record a maximum of 2,000 readings at a minimum of four second intervals before it has to be reset The HAMS measured the dust levels axle in the Before operator's each brake breathing zone and in the maintenance job the HAMS area were beneath the vehicle's calibrated and zeroed The computer's clock was synchronized with that of the video camera DuPont P4000 or MSA Model G pumps were connected by tubing to each HAM and each HAM in turn was connected by a foot electrical lead to the computer programmed to receive the data The brake maintenance operator wore one HAM and the other HAM was set beneath the axle of the vehicle undergoing brake maintenance The computer recorded these dust levels on a disk from which a plot was later made By comparing the plot to the video recording of that brake maintenance operation dust sources due to work practices and enclosure leaks could be identified Although the HAMS are not specific for asbestos if the asbestos fibers are dispersed along with the other components of the brake dust which seems to be a resonable assumption then the HAM should be a useful real time indicator for control of asbestos laden dust Using a spreadsheet program Lotus 1-2-3 a time plot of the dust was made By comparing the peaks from this plot with the video work practices producing elevated dust levels can be identified levels Ventilation Kurz Model No. 480 and TSI Model No. 1630 air velocity meters were used to 12 fue 16 16:01:116:201:12 2001 16 measure air velocities to garage Smoke tubes were patterns determine flow used to assist rates and wind in observation directions of general in the airflow Air temperature humidity and wind conditions were determined using an aspirated psychrometer and velocity meters Ergonomic Evaluation of Brake Maintenance and Repair An ergonomic evaluation was conducted on workers performing brake maintenance and repair to determine work practices which may cause personal asbestos dust exposure while during routine using brake a brake washer inspection and assembly unit Each worker was videotaped brake replacement tasks Work cycle times and work analysis were performed from videotapes in the laboratory Cycle times were taken while running the video tapes at normal speed while work analysis was conducted at both normal speed and by action techniques Work analysis included breaking the job into general tasks which could be matched with airborne dust levels during brake Work tasks which could cause personal exposure inspectiaonnd replacement to brake dust were identified Interviews were conducted with eight vehicle maintenance workers who do brake work Data were collected on a standardized questionnaire see Appendix B and analyzed Basic descriptive demographic and work history data were gathered from each worker Information from these interviews were compared to workplace observations by the NIOSH research team IV RESULTS Time Sampling Resuits Real total total dust data were collected using Held Aerosol Monitors HAM's connected to an Apple II Plus computer Two time samples were collected one alongside the personal sample on the brake mechanic and the other just below the vehicle's axle time data collection was during actual brake maintenance operations approximately an hour in duration and was obtained during all 10 brake maintenance jobs Nine different operators performed the brake maintenance jobs on these 10 vehicles The general brake maintenance procedure was - Remove the wheel's lug bolts and the wheel average time 17 seconds - Remove the brake drum average time 17 seconds Thirty percent of the operators let the cleansing liquid run down between the brake drum and the support plate for about 15 seconds before removing the drum - Thoroughly wash the drum brake shoes and brake support plate for about 80 seconds - Inspect the brake shoes If they do not need replacing reinstall the brake drum wheel and lug bolts average time 60 seconds 13 1120+ 16 16:10:116:410:14 2081 . - For brake shoes that are to be replaced remove the brake shoes average time 100 seconds For 30 of the replacements the operator would wash the support plate and related gear for another 10 to 40 seconds - Install the new brake shoes average time 280 seconds - Reinstall the brake drum average time 10 seconds - Remount the wheel and tighten the lug bolts average time 60 seconds To interpret the time computer data the instruments background level 0.05 millivolts is used as the reference point at this facility This background level is the Apple's internal noise level and values below it are considered to be unreliable as to accuracy and were not used Values above this reference level are used to identify the dust sources By determining the magnitudes value above the reference point with time these dust exposures relative dust exposures due to certain phases of of the brake job can be identified and compared Real data detected brief elevations of total dust during the removal of the INP lug bolts and the drum and greatest potential Aghegros during the reinstallation of the lug bolts oust exposure occurs during removal of the Coote 1 AL de Cote 1 _ _ 11 ht 1 LIL ge -r to contain asbestos fibers For 38 of the drums removed dust levels were up to nine times that of the reference level For each brake jah the worker WHY exposed to olovated duct lovoit from 11 to 11.0 avoraging 3.6 of the , total time spent in removing the brake drums The second highest dust levels detected were during the removal of the lug bollo from the whocio Thooo lovolc woro up to throo timos tho referenco level on 38 of the brako jobc When roinstalling the wheel and tightening the lug bolts dust levels were up to 1.5 times above the reference level in 10 of the operations For each brake job the worker was exposed to elevated dust levels 0 % of the total time spent in loosening and lightening of the lug bolts Removing the old and installing the new brake shoes regulted in alightly elevated dust levels up to 1.5 times above the reference level in % of the blakes replaced Put each brake jub Lhe wucher was capused to elevated Just levels from 0.2 to 0.3 of the total time spant in removing and instulling of the brake shoes On the third brake maintenance operation there exposures during the time it took to remove the Just levels were seven to night times shave the were prolonged elevated dust lugs from two wheels The reformer level and averaged 5.1 of the total brake maintenance time for two wheels on one vehicle When the impact wrench was replaced dust levels and exposure time both dropped indicating a faulty impact wrench Also noted was the cleanliness of the ime. of L. ful whotls 20 could wheels the amount of road be described as clean CO dust on the Fair and 20 14 Tum 16 16 THAT P. 13 dirty From the time data there was no clear relationship between dusl exposures and cleanliness of the wheel The greatest potential to ashestos ex ngure is during the remoiral of the brake drum This potential appears to be reduced when the cleansing liquid is allowed to flow between the broke drum and brake support plate before the drum is removed The nign Aust level experienced during the removal and tightening ot the lug bolts appears to be due more to the impact wrench than the road dust on the rim One faulty or worn out impact wrench significantly increased the total dust levels when it was used on two of the forty wheels as noted previously by directing compressed air onto the wheel being serviced The elevated time dust readings may also have been from an oil mist aerosol from the wrench generated by the compressed air Thorough washing of the brake support plate brake shoes and gear used to attach the brake shoes appeared to remove or wet most of the asbestos dust before the operator started to manually remove the old shoe and install the Now 41 sh sS. A " rull total dual of brake shoe replacements lavala vard low a h^k Adurable char 18 Air Sampling Results Individual filium sumpla muoulto fom olmboemo ombo0400 Sibere oes unted in Table A of Appendix A and are summarized in Tables 1 and 2. The results for samples analyzed by Phase Contrast Microscopy PCM are presented in Table 1 Personal asbestos sample concentrations for the brake mechanics averaged less than the detection limit of 0.004 fibers with only one sample above 0.004 fibers Source samples taken above the wheel fender averaged less than 0.002 fibers source samples hung over the axle and centered between the two wheals avaraged less than separate locations in the 0.002 fibers background samples collected at garage averaged less than 0.001 fibers and outdoor ambient samples averaged less than 0.001 fibers As stated earlier TEM analysis of these samples show that more than 85 of the chrysotile fibers counted using the A rules would also have been counted using the B rules Nineteen of the 20 personal samples taken during 10 brake jobs were below the dotoction limit of 0.004 fiborc Because personal sample concentrations represented exposures while servicing brakes and this usually takes no more than 2 to 3 hours per shift the mechanics weighted averages exposure would be even lower than the measured levels Only 1 of the 76 samples analyzed by PCM was above the detectable limit thus analyses comparing brake mechanics type of vehicle and differences between brake inspection and brake replacements were not done Transmission Electron Microscopy TEM results are summarized in Table 2. fibers identified as chrysotile or amphibole asbestos with an aspect ratio 1 or greater were counted fibers 0.25 microns and longer are included few samples contained fibers that were not identified no I.D. but could possibly be asbestos Ail of 4 15 Tue : 1K 14.1186 CHILT F. Table 1 Phase Contrast Microscopy Concentrations fibers for 10 Vehicles Sample Type Number of Samples Arithmetic Mean Range Personal Fender Axle Background Ambient 20 0.004 0.004 - 0.006 10 0.002 0.002 0.002 10 0.002 0.002 16 0.001 0.001 8 0.001 0.001 Table 2 TEM Concentrations for 10 Vehicle fibers Brake Jobs Sample Type Personal Fender Axle Background Ambient Number of Samples Arithmetic Mean 10 10 10 8 4 0.008 0.009 0.004 0.002 0.002 Standard Deviation 0.003 0.012 0.004 0.001 0.001 Range 0.006 -- 0.013 0.002 - 0.040 0.002 ~ 0.016 0.001 - 0.006 0.002 -- 0.003 16 Itim . 1 ove Pegsduysns QUE 21 The arithmetic mean TEM concentration Table 2 for all personal samples was 0.008 fibers with a standard deviation of 0.003 fibers This concentration was higher than the background levels in the building which averaged 0.002 fibers and the outdoor ambient levels which averaged 0.002 fibers Source samples taken at the axle averaged 0.004 fibers while samples taken at the fender above the wheel averaged 0.009 Fibers The TEM source sample results were only slightly above background levels Because most concentrations were below detectable limits and detectable concentrations were not much above detectable limits tests of significance were not performed on this data Asbestos fibers chrysotile or amphibole greater than or equal to 5 um in length were found in only 12 of the 48 samples analyzed by TEM Two personal samples showed fibers greater than 5 um Asbestos fibers that were in a matrix partially hidden by particles fibers and X fibers - fibers that extended into another field - are not included in Table 2 but are denoted in Appendix A. Four of 48 samples analyzed by TEM contained M or X asbestos fibers and one of these samples would show substantially higher concentrations had M or X fibers been included Bulk and Rafter Sample Results Bulk samples were collected from the drums of nine of the vehicles tested In addition a rafter sample was collected and analyzed The bulk sample results are presented in Table 3. Less than % of the of the bulk samples and the rafter sample were total material dust in each asbestos although asbestos constituted virtually all the fibers that were found From 83 to 100 of the fibers in the 9 brake drum bulk samples were chrysotile with two of the nine samples containing 100 chrysotile asbestos fibers bulk samples contained amphibole fibers From 0 to Two of the brake drum % of asbestos fibers and bundles were longer than 5 microns Three percent of the fibers from beake job No. 1 bulk sample were larger than 5 um The remaining eight bulk samples ; contained % or fewer chrysotile fibers longer than 5 microns The rafter sample contained 99 chrysotile fibers with % of the asbestos fibers larger than 5 microns The OSHA Standard or 0.2 Fibers Action level 0.1 fibers cc and the NIOSH recommended exposure limit of 0.1 fibers for asbestos 8 hour time weighted average are based on PCM analysis of asbestos using A counting rules B counting rules were utilized in this research study As noted earlier TEM analysis of these counted using the samples show that more than 85 of the A rules would also have been counted chrysotile fibers using the B rules Based on the levels measured by both PCM and TEM however the mechanic's expocure in this study would be well below these recommended levels , CONTROL TECHNOLOGY Occupational exposures can be controlled by the application of a number of known principles including engineering measures ventilation isolation and substitution work practices and personal protection Ongoing monitoring and maintenance of controls to insure proper use and operating conditions and the education and commitment of both workers and management to occupational health are also important ingredients of a complete effective and durable control system These principles of control apply to all 17 The oe ch 11. HH HH 13 201 %, a Brake Job Vehicle & Year Sample No. i Jeep 1976 2 Z 1977 3 - 3 1977 4 - 4 1978 S * S 1977 6 ^ 1978 7 7 1981 8 . 1973 10 1974 13 Rafter 1 Table 3 Bulk Sample Results Grids Examined Amphibole Number of Chrysotile and Amphibole Fibers I of Total Fibers Chrysorile and Amphibole Chrysorile and Amphibole Fibers 15 um 9 No 83 4 No 97 3 1 116 10 222 222 00 115 " No 112 10 1 41 10 22 54 10 22 19 00 No 100 83 3 88 0 96 0 97 0 97 Oo 97 ww 100 100 a 85 > > 7 * Includes fibers fibers in a matrix and bundles 18 Tae er 16 16.910 4 14 2081 F situations but their optimum application varies from case to case application of these principles are discussed below The Engineering controls The all brake brake washer lining assembly unit is used at this garagteo contain and collect dust including potentially hazardous asbestos fiber content all brake The unit which is inspection repair fully described in Section II and brake lining replacement is used during In this study the entire brake service job was monitored including all four wheels The results discussed below represent fiber PCM and asbestos TEM concentrations during the entire brake job consisting of all four wheels The effectiveness of the brake washer assembly is evidenced by the very low exposures for the brake mechanics Nineteen of the 20 personal samples analyzed by PCM were below the detectable limits of 0.004 fibers well below the current OSHA standard of 0.2 fibers and the NIOSH recommended standard of 0.1 fibers Low for the source sample placed on fiber concentrations by PCM the fender directly above the were also found wheel After completing servicing to the first wheel this sample was above the other wheels so that this sample included dust moved to the fender emissions from all four wheels The fender sample concentration for each of the was less than 0.002 fibers The other source sample hung showed concentrations of less than 0.002 fibers for all 10 10 brake jobs over the axle brake jobs The importance of this source sample is that it shows dust fibers propelled by the brake washer assembly unit liquid toward the the vehicle As noted earlier TEM analysis of these samples than 85 of the chrysotile fibers counted using the A rules were not being other side of show that more would also have been counted using the B rules TEM results were also used to evaluate the effectiveness of the brake washer assembly unit The TEM results are not directly comparable to the PCM data because TEM includes all size fibers whereas PCM includes only fibers longer than 5 um and with a diameter greater than about 0.3 um and TEM includes only fibers identified as asbestos whereas PCM includes all fibers larger than 5 um The TEM personal sample results Table 2 show asbestos fibers were controlled to very low levels with use of the brake washer assembly The personal sample arithmetic mean concentration and geometric mean concentrations were 0.003 and 0.009 fibers respectively for all 10 brake . jobs Fender sample asbestos concentrations were very low ranging detectable limit of 0.004 to a high of 0.040 fibers The from axle samples were also very low ranging from 0.004 to a high of 0.016 the source fibers Background and ambient asbestos concentrations by TEM averaged 0.002 fibers These low asbestos levels indicate that the asbestos in the personal not from and source samples outdoor sources or was from activities such from resuspended dust in as brake servicing the garage and The sampling at the Nashville Postal Service weather October with some doors open most garage of the was conducted in mild time Natural ventilation 19 Ilim 11. 1 :: ; 2013 P. 2323 Table 4 Work Task Analysis of Brake Inspection and Replacement Step Work Task Brake Dust Exposure Sources 1 Use pneumatic wrench to remove fivo lugo from whool Loose rim dust around lugs and tire 2 Remove wheel from vehicle 3 Remove brake drum and sets on floor Loose dust from drum and brake components may become airborne 4 Worker positions brake assembly washer unit under brake assembly 5 Worker uses wet brush stylus to clean brake components 6 Worker removes brake components and When brake components are not cleans each piece throughly washed in step 5 7 Worker cleans axle surface loose dust from components during removal and installation in steps 6 and 8 8 Worker assembles brake components and installs new brake shoes 9 Brake drum is wet washed with brake washer assembly unit wiped put back on brake unit clean and 10 Wheel is put back on vehicle 11 Wheel luge are pneumatically tightened wheel Loose rim dust around lugs and tire 20 Lue eh 14. 14. HI fob ee P. 24 due to the open doors may have helped to minimize the airborne asbestos levels although there was no measurable increase in the personal source or background levels when some doors were closed Work Practice Results Table 4 shows the work task analysis of a brake inspection and replacement job while using the brake washer assembly unit Potential asbestos exposui^' points while performing this task are also noted The average work cycle time for a wheel brake inspection task was 12 minutes As seen from Table 4 asbestos exposure during brake maintenance and repair may occur during the initial tasks of removing the wheel and brake drum from the vehicle Good work practices observed by some of the workers to reduce these exposure points are the use of a wet brush on the wheel and on the back of the brake drum and assembly to suppress dust before removing the brake drum Bad work practices included using a dry rag to wipe down the brake drum and assembly as a substitute for the wet wash unit the use of a hammer to loosen frozen brake drums without first suppressing dust with wet control methods and taking soiled clothing home to wash Demographic and work practices were obtained from interviews of eight workers All eight workers were male ranged in age from 19 to 54 years and the average age was years experience as 38.2 - 12.8 years As a mechanics and performed group these men 5.6 - 2.5 brake had 4.0 + 1.9 jobs per week The other job duties included general maintenance engine tune repair work and use of hydraulic equipment Seven of the workers indicated their right hand was dominant in performing work while one claimed to be ambidextrous Tools and equipment commonly used during brake maintenance and repair included brake spring remover pliers hammer brake washer unit solvent dust mask brake adjustment tool brake shoe loul power air tool and impact wrench Five of eight employees indicated they were provided with training with regard to asbestos exposure during brake maintenance the training lasted anywhere from one to eight hours and usually took place when employees started working with the U.S. Postal Service Workers remembered from their training precautions and not the use of a respirator to use compressed air to clean blow out procedures and safety brake dust All eight workers indicated they had a physical examination before being hired by the Postal Service and all but one employee indicated having a physical exam within the past year one employee indicated a physical exam in March 1985 Three of eight workers reported having an ray as part of their physical examination Analysis of workers with and without rays showed an age dependent pattern with all three workers who had rays being over 40 years of age When asked if the workers did anything special to protect themselves for brake dust all indicated use of a dust respirator and use of the brake washer assembly unit Personal protective equipment worn by all workers included work clothing and a respirator gloves and other items such as safety glasses and safety shoes were not indicated Shower facilities were available for all workers however only three indicated regular use before leaving work Two trainee workers reported they did not change out of their work clothes before Pa 21 Tue 8 62 16 16:30 16:30 : 2001 B.S leaving service work The U. S. Postal Service for the regular work force provides work clothes and laundry In summary this information revealed that these workers were aware of the hazards of asbestos exposure while working on brakes In addition they generally used control devices such as disposable quarter mask respirators nuisance dust and the brake washer assembly unit when performing brake maintenance and repair for VI CONCLUSIONS AND RECOMMENDATIONS The for use the of this brake washer assembly resulted in very low asbestos exposures vehicles tested indicating effective control of the asbestos dust Although it was not possible to evaluate an uncontrolled situation to determine an efficiency for the controls other work has shown peak exposures using NIOSH Analytical Methods CAM 239 of around 1 fiber and time weighted average expocure of around 0.2 fiberc with dry bruching or compressed air blowing This data suggest that the present technique was substantially effective in controlling asbestos dust during brake servicing Fender and axle source sample results showed no major differences among the vehicles tested There was almost no difference in asbestos exposures between brake inspections and brake replacements based on TEM results TEM results were of much greater value than PCM results for evaluating the brake assembly washer since the asbestos levels were quite low The primary use of the PCM data was to demonstrate that exposures were well below the OSHA standard and NIOSH recommended level since both the standard and recommended level are based on the PCM procedure As noted earlier TEM analysis of these samples show that more than 85 of rules would also have been counted the chrysotile fibers using the B rules counted using Since the TEM the A method is more sensitive and background and this allowed comparison between personal or source ambient levels all of which were quite low samples Bulk sample results analyzed by TEM show that the brakes of the vehicles tested in this study contained chrysotile asbestos fibers and therefore had asbestos brakes Fibers found in the drums of the nine vehicles tested were between 83 and 100 chrysotile with 2 vehicles having 100 chrysotile fibers Less than % of the total material dust in each of the bulk samples and the rafter sample were asbestos although asbestos constituted virtually all the fibers that were found An analysis of the video and real total dust data indicates that some dust emission peaks may be reduced by altering work practices such as 1 allowing the cleansing fluid to flow between the brake drum and brake support plate before the drum is removed and 2 after removing the brake drum throughly wetting the wheel hub and the back of the brake assembly to suppress dust and then thoroughly washing the brake support plate brake shoes and brake components used to attach the brake shoes before the operator starts to manually remove the old shoes 22 Lue 8 13:11 11. 13:11 13:11 .- . Shuts Ph Training in the developing good exposure operation and maintenance of this work practices which could reduce unit is important for potential brake asbestos Mild weather with levels than might closed some of the doors occur during cold open may have resulted weather when the doors in lower ambient are normally kept Since asbestos was identified in most brake dust samples showers are recommended as a good practice before going home from work to remove any residual dust from the body and a laundry service should be provided for cleaning soiled work clothing Further education about personal hygiene i.e. showers at work and changing soiled work clothing before leaving work may provide additional protection by not bringing asbestos dust to the home environment Maintenance and regular changing of the brake washer assembly solution is encouraged for maximum efficiency of this unit see manufacturer's recommendations VII REFERENCES 1 Dubrow Robert and David Wegman 1983. Setting Priorities for Occupational Cancer Research and Control Synthesis of the Results of Occupational Disease Surveillance Studies Journal of the National Cancer Institute 71 1142 2 Roberts Dennis R. and Zumwalde Ralph D. 1982. Asbestos Exposure Assessment for Brake Mechanics Industrial Hygiene Summary Report No. 32.4 NIOSH November 1982 3 Current Intelligence Bulletin 5 Asbestos Exposure During the Servicing of Motor Vehicle Brake and Clutch Assemblies National Institute for Occupational Safety and Health August 8 1975 4 Newhouse M.L. and H. Thompson Mesothelioma of Pleura and Peritoneum Following Exposure to Asbestos in the London Area Brit J. Ind Med 261 261 9965 5 McDonald A.D. et al Epidemiology of Primary Malignant Mesothelial Tumors in Canada Cancer 914-19 1970 6 Greenberg M. and T.A. Lloyd Davies Mesothelioma Register 1967-1968 Brit J. Ind Med 91-104 1974 7 Lorimer V. A. Rohl A. Miller W.J. Nicholson and I.J. Selikoff Asbestos Exposure in Brake Repair Workers in the United States Mt. Sinai J. of Med 207-218 June 1976 23 eer Ti, Per nibs as JH . Boot Bader M.E. R.A. Bader A.S. Teirstein A. Miller and I.J. Selikoff Pulmonary Function and Radiographic Changes in 598 Workers with Varying Duration of Exposure to Asbestos Mt. Sinai J. of Med 492-500 1970 Davis Heated J.M.S. and S.W. Coniam Experimental Studies on the Effects Chrysotile Asbestos and Automobile brake Lining Dust Injected of into the Body Cavities of Mice Experimental and Molecular Pathology Vol 19 PP 339 3531973 10 Koshi K. H. Hayashi and H. Sakabe Studies on Serpentine Minerals in Heat Vol 7 pp 66-85 1969 Biological and Treated State Mineralogical Ind Health 11 Pott F F. Huth and K H. Friedricks Tumorigenic Dusts in Experimental Animals Environmental Health Vol 9 pp 313-315 1974 Effects of Fibrous Perspectives Pott F. F. Huth and K.H. Friedricks Tumorigenic Effects of Fibrous Experiments Concerning the Carcinogenic Effects of Fibrous Dusts Interpretation of Results Considering the Carcinogenesis in Humans Annales d'Anatomie Pathologique Paris 1976 Vol 21 pp 237-246 13. Davis J.M.G. Pleural Cavity The Fibrogenic Effects of Mineral Dusts Injected into of Mice British Journal Exp Pathology Vol 53 pp 190-201 1972 the 14 Stanton M.F. M. Layard A. Tegeris The Carcinogenicity of Fibrous Glass Relation to Fiber Dimension J. Natl 1977 E. Miller M. May and E. Kent Pleural Response in the Rat in Cancer Institute 587-603 March . 15 NIOSH 1976 Revised Recommended of Health Education and Welfare p 93 December 1976 Asbestos Standard U.S. DHEW NIOSH Publication Department No. 77 169 16 NIOSH 1984 Statement of the National Institute for Occupational Safety and Health the Public Hearing on Occupational Exposure to Asbestos June 21 1984. Testimony on Proposed Rule Making at OSHA Hearings NIOSH Method Edition Vol 7400. 1984 NIOSH Manual 2 DHHS NIOSH Publication of Analytical No. 84-100 Methods Third Burdett Garry .. and Anthony P. Rood 1983 Membrane Transfer technique for the Analysis of Asbestos Fibers or other Inorganic Particles by Transmission Electron Microscopy American Chemical Society Environmental Science and technology 643-649 24 Tc . D 780I9zSy Xacy ad 3/2490Cate el e Cate Fg c - cr c 2 c c - c - 1 cr ~ - c - c c C C c - c - Cc Asbeto ow Vehicle- C'o JypeJype Vehicle: Year Jype Inspact 2 ( ) Youne Youne Youne . Fibers Fibers / Fileri Fileri / co . 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RESZ 652"A6SZ 7650 SRHSZ TEAST 7662 8652 C667 6962 8RAS7 TRESZ ALESC 0L6S7 69KST SL6S7 91652 9652 $9687 69657 Ste