Document g2EbvLzDXdgkMpXnr4npeVBbN

PB88162193 Information Is our business. IN-DEPTH SURVEY REPORT: EVALUATION OF BRAKE DRUM SERVICE CONTROLS AT UNITED STATES POSTAL SERVICE, VEHICLE MAINTENANCE FACILITY, NASHVILLE, TENNESSEE, NATIONAL INST. FOR OCCUPATIONAL SAFETY AND HEALTH, CINCINNATI, OH. ENGINEERING CONTROL TECHNOLOGY BRANCH AUG 1987 U.S. DEPARTMENT OF COMMERCE National Technical information Service Tailored to Your Needs! Selected Research In Microfiche SRIM is a tailored information service that delivers complete microfiche copies of government publications based on your needs, automatically, within a few weeks of announcement by NTIS. SRIM Saves You Time, Money, and Space! Automatically, every two weeks, your SRIM profile is run against all new publications received by NTIS and the publications microfiched for your order. Instead of paying approximately $15-30 for each publication, you pay only $2.50 for the microfiche version. Corporate and special libraries love the space-saving convenience of microfiche. 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U.S. DEPARTMENT OF COMMERCE Technology Administration National Technical Information Service / Springfield, VA 22161 (703)605-6000 http://www.ntis.gov V 4 IN-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. Dennis M. 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 J 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 Facility 707 Chestnut Street 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, 615/742-0207 Robert Hart, Supervisor, Vehicle Maintenance, 615/742-0203 James C. Hollingsworth, Chief Steward Nashville Local American Postal Workers Union, AFL-CIO Eugenia Shtrom, PEI, and Data Chem formerly Utah Biomedical Testing Laboratory 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 Welfare), it was established by the Occupational Safety and Health Act of 1970. This legislation mandated 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 research deals with methods for controlling occupational exposure 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 or process of interest, and to create a more general awareness of the need for or availability of an effective system of hazard control measures. These studies involve a number of phases. Initially, a series of walk-through surveys are conducted to select plants or processes with effective and potentially transferable control concepts or techniques. Next, in-depth surveys are conducted to determine both the control parameters and the effectiveness of these controls. The reports from these in-depth surveys are then used as a basis for preparing technical reports and journal articles on effective hazard control measures. Ultimately, the information from these research activities builds the data base of publicly available information on hazard control techniques for use by health professionals who are responsible for preventing occupational illness and injury. Background Asbestos is found in motor vehicle brake materials. Recognition of asbestos' carcinogenic properties has currently resulted in substitution of less toxic fibers for some brake materials. However, asbestos is still used in a large number of brakes. 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. On the basis of the principles outlined in their paper, some priorities for research 1 and control clearly stood out. Their results pointed to the investigation and control of occupational exposure to asbestos as the number one priority in 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.(2) other estimates run as high as 900,000 workers being potentially exposed in brake servicing. A study of brake service operations was needed because of the following: the known carcinogenic potential of asbestos; a large number of workers are potentially exposed; primarily small businesses perform brake servicing and lack resources to evaluate control devices; and the general lack of 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 effectiveness of various control techniques used during brake repair, and the transfer of the documented information to the appropriate individuals 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 wiping/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 for proper fit and adjustment in the final phase of the servicing operation. The brake repairman and other service personnel in the garage area are potentially exposed to asbestos dust during and following the brake drum removal. If the normal dust buildup inside the drum and brake assembly is removed and disposed of in a controlled manner, this hazard can be minimized. Site Selection Preliminary surveys were conducted at 10 sites using a variety of control techniques. These site visits were conducted to observe the control techniques in use and to select sites for detailed sampling studies. Sites were selected primarily from fleet garages to control for variables such as vehicle type, use, and maintenance practice, and on the physical size of the garage. Selection of sites was made, as judiciously as possible, based on criteria including: 2 a) The type of control technique(s) 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 repair workers includes asbestosis, lung cancer, and mesothelioma.(4-8) In a detailed examination of 90 union motor vehicle maintenance workers in New York City^7) with 10 or more years of shop work, 29% had decreased vital capacity; the percentage increased with age and most markedly after 20 years from the onset of auto work. Many of the workers examined showed signs consistent with asbestosis, with observed changes noted in chest X-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 asbestos. Many of the asbestos fibers originally present in the unused brake shoe chemically degrade due to the high temperature encountered in use. Chrysotile asbestos fibers exist in automobile brake dust in various states of deformation. Unlike chrysotile, the health effects of exposure to forsterite (a deformation product of chrysotile), or to transition series fibers (chrysotile/forsterite) with altered crystalline structures are not well documented. In studies by Davis and ConiamO) and KoshidO) in which fibers of chrysotile, chrysotile/forsterite, and forsterite were injected into the pleural and peritoneal cavities of mice, the results suggested varying degrees of toxic effects. Fiber implantation animal studies conducted by Pott, et. al.,(H12) and Davis, et. al.,^3) suggest that the morphology and size of a fiber, regardless of fiber type, are responsible for its carcinogenicity. Likewise, Stanton, et. al.,^1^) suggests that fibers less than 1.5 urn in diameter and greater than 8 um in length pose the greatest risk in producing pleural sarcomas. These studies tend to suggest that the physical morphology (size dimensions) and to a lesser degree chemical and surface characteristics of a fiber are the determining factors for inducing a biological effect. The 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 workers and the lack of a clearly identified no-effect level for asbestos, it is important to minimize exposure to brake dust which may contain asbestos. The two sources of occpuational exposure criteria considered in this study are: (1) the NIOSH Recommended Exposure Limit (REL), and (2) the Department of Labor OSHA Permissible Exposure Limit (PEL). NIOSH recommends that employee exposure to asbestos be reduced to the lowest feasible limit, due to the carcinogenic nature of this substance. The NIOSH 3 REL published in 1976 is 0.1 fibers greater than 5 ym in length per cubic centimeter (f/cc).(*5) NIOSH submitted an update on the recommended asbestos criteria at the OSHA proposed rule-making hearings for asbestos in June 1984.(16) The NIOSH position is summarized below: The carcinogenic potential of asbestos is no longer in doubt; however, there is some uncertainty about the toxicological 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. Virtually all levels of asbestos exposure studied to date demonstrated an excess of asbestos-related 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 may conclude that asbestos is a carcinogen capable of causing lung cancer and mesothelioma, independent of smoking. NIOSH has recommended that asbestos be controlled to the lowest detectable limit. It is our contention that there is no safe concentration of exposure to asbestos. Any standard, no matter how low the concentration, will not ensure absolute protection for all workers from developing cancer as a result of their occupational exposure. However, lower exposures carry lower risks. Since the only widely available method, NIOSH Method 7400,d?) is able to achieve (intralaboratory) accuracy of 12.8% RSD at an exposure limit of 0.1 f/cc (100,000 f/m3) in a 400 liter sample, NIOSH and others have recommended an exposure limit (REL) of 0.1 f/cc for asbestos based on 8-hour time-weighted average concentrations.While this is a well understood practice, we can not find compelling arguments to prevent a recommendation based on alternative sampling periods. In fact, such an approach may provide more protection than an 8-hour based sampling period that allows short-term exposures 6 or 10 times greater than the 8-hour exposure limits being considered by OSHA. Furthermore, since there is uncertainty regarding the cumulative dose required to initiate disease, it seems reasonable to make every attempt to control exposures to as narrow a range of concentrations as possible. One way to accomplish this is to restrict the period over which workplace concentrations can be averaged. Personal sampling pumps are available, with flow rates up to 3.5 1pm, which would allow a sampling time of two hours or less. 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 As noted, the occupational exposure criteria - the NIOSH REL and the OSHA PEL- are based on the readily available Phase Contrast Microscopy analytical method. This method has inherent limitations based on the physics of the optical microscope and upon the ability of the counters to reliably discriminate the specified length to width ratio in a complex sample matrix. The minimum diameter routinely observed is on the order of 0.5 pm. The NIOSH 7400 method stipulates that only fibers longer than 5 pm be counted with a length to width ratio of either 3:1 ("A" rules) or 5:1 ("B" rules). The "A" rules use the same aspect ratio as the current OSHA standard, and thus have the advantage of relating to current and historical compliance data. 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 differentiate the numbers of fibers with various length to width ratios. A coarse analysis of this data indicates that fiber counts using NIOSH 7400-A and 7400-B counting rules would differ by less than 15%. Another concern is that asbestos fibrils as small as 0.02 pm in diameter and less than 1 pm in 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 effect of small fibers (and thus what sizes of fibers should be counted) adds further ambiguity to this area. On June 20, 1986, OSHA issued a revised standard PEL, which reduced the PCM level to 0.2 f/cc, as an 8-hour time-weighted average (TWA) exposure. It also set an action level of 0.1 f/cc that triggers worker training, medical monitoring, and other requirements. The new standard does not set a ceiling or short-term exposure limit. II. PLANT AND PROCESS DESCRIPTION Facility 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 so that total vehicle mileage on all routes stay approximately the same. All the garage shop personnel are members of the American Postal Workers Union, AFL-CIO. In the entire Sectional Center District, the Nashville vehicle maintenance facility services the following: 5 1) Five hundred and seventy-five 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 575 vehicles are the AM General Post Office delivery vehicle type, and the remainder are special vehicles. Most of the delivery Jeeps and all the 1/4 and 1/2 Ton units have 6-cylinder engines - the remainder have 4-cylinder engines. 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-DJ5D. 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. g) Transmission - Automatic. h) Differential - limited slip rear wheel drive. 2) Thirteen seven-ton International trucks (disc brakes all four wheels). 3) Three Mack and two White tractors (drum brakes all four wheels). 4) Seven trailers. The garage is staffed with nine mechanics, one lead mechanic, four garagemen, one body man and two supervisors. Six mechanics work from 6:00 a.m. to 2:30 p.m. and four mechanics work from 9:30 a.m. to 6:00 p.m., with all 10 mechanics on duty from 9:30 a.m. to 2:30 p.m. The garage building sides face East and West and is 202 feet long with a working area of 64 by 111 feet and a ceiling height of 20 feet. There are seven bay doors on each side with each door approximately 14-feet high and 11-feet wide. A plan of the working area is shown in Figure 1. When the garage was opened in 1979-80, building heat was provided by a bank of six electrical heaters (equipped with small fans) suspended in a row on each side of the garage (12 heaters). Because these units were expensive to operate, they are no longer used. In their place, four gas-fired unit heaters were installed at each comer of the garage. There is an under-floor hose and pipe system to remove auto exhaust fumes. These are located in the floor by the doors of the 14 bays. Six of the bays 6 are equipped with hydraulic lifts (both front and rear of each vehicle) so they can work on twelve elevated vehicles at the same time. Each bay has a working width of 13 feet. Numerous electrical cables are 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 roof-mounted fans on each side of the garage. These are operated in summer to remove hot air from under the roof area. In the cooler months, these fans are not used and the inlet dampers are kept closed. There is no provision for providing fresh, heated air from the outside. When the 14 bay doors can be left open during mild weather, they provide a lot of useful ventilation. During colder weather, the garage air temperature is kept at 60-65F at the mechanics working level. Process and Equipment Description This facility is currently replacing asbestos brake shoes with the nonasbestos type when vehicle brakes are repaired. Our control evaluation at this facility concentrated on Jeep vehicle maintenance to determine the variability of control effectiveness in the same model vehicle during 10 separate vehicle brake repair or inspections. A $760 brake washer assembly unit (Kleer-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 unit was not evaluated in use on any type of vehicles except jeeps, supervision reported good results when using this unit on the larger vehicles as well. The portable washer moves easily to the brake repair location. A water solution (Greasoff No. 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 any dust and perform the necessary cleaning. The solution is returned to the bottom tank where it is recirculated. The upper tray is removable to permit use of the bottom tank for 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 discarded. (Four gallons of Greasoff No. 19 cost $75.) Greasoff No. 19 contains the following hazardous ingredients; less than 5% by weight sodium metasilicate, a highly alkaline compound (pH 12.4), and less than 5% by weight ethylene glycol monobutyl ether, which is also known as 2-butoxy ethanol or by its common name of butyl Cellosolve. Sodium metasilicate is severly irritating to the eyes, skin, and mucus membranes. Ethylene glycol monobutyl ether or 2-butoxy ethanol is absorbed by the skin and is a hemolytic agent. The current OSKA standard for 2-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 7 MAINTENANCE GARAGE (2 0 2 ` 3ii 4 it { i i * CO u ^ 5o* **-* B X* CO .M u 1 -* V 09 vi In w * oN 2 c CM o I I 63 6 O w w a I^ oO CO CO ^ Ed g 5S *-2 1 E-| oCO | C*4M P* Ed E-* Ed u o 1 oo 09 ON CO 33 CO 1< z > J<oSao, V) Tae3 aaio au w eon M S ae owo aui 3 00 8 9 F ig u re 2. Brake Washer Assembly U n it. side shield safety glasses and rubber or chemical resistant clothing is recommended for preventing skin contact when handling Greasoff* No. 19. The washer unit has a six-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 five-gallon cans and marked in accordance with EPA instructions for disposal. An EPA-approved contractor picks up the used liquid and disposes of it in an EPA-approved toxic waste site. Some of the features of the brake washer assembly include: 1) A gentle flow of solvent to the workshelf/catch basin area to wet the back plate and brake components in order to avoid spreading dust into the air and, at the same time, clean the components. 2) A low center of gravity to avoid tipping and spillage of solution which may contain asbestos fibers. 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. 5) A reservoir equipped with a removable cover to prevent liquid evaporation when covered and as a work tray when the cover is removed for work on large vehicles. 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) Hake sure the switch is in OFF position and plug into power source. 3) Make sure the brush 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-end 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 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 hose-pump connection. 6) The "Flo-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 assembly unit and believed it did a good job of containing and collecting brake dust when employed on any size vehicle. III. METHODOLOGY Air Sampling and Analysis Personal air samples for asbestos were collected in duplicate on 0.8-um pore size, 25 mm-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/cc 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 were used to measure fibers escaping into the working environment during the cleansing and repair activity. The minimum volume collected (840 liters) allowed a limit of detection of 0.002 fibers/cc by PCM. Two additional area samples were collected in the general garage area (background) at approximately 7.0 1pm for a 4-hour period encompassing pre- and post-brake job activities. These background samples were used to determine effects of general shop cleanliness and overall containment effectiveness of the controls. The minimum volume collected (1,680 liters) allowed a limit of detection of 0.001 fibers/cc. Two other area samples were collected out of doors several hundred feet from the building at 3.0 1pm for an approximate 8-hour period. These ambient samples were used to determine environmental levels of asbestos. The minimum volume collected (1,440 liters) allowed a limit of detection of 0.001 fibers/cc. 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 light-field Transmission Electron Microscopy (TEM). To facilitate analysis by PCM and TEM on the same samples, the direct transfer method of sample preparation described by Burdett and Rood^S) was used. For PCM analysis, all fibers with a 5:1 (or 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 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 and submitted for PCM and TEM analysis. Twelve blanks were analyzed by PCM and 6 blanks by TEM and these results are shown in Table 1 of Appendix A. Analysis by PCM and TEM show all blanks were below detectable limits. 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 of fibers that were asbestos was quantitatively determined; the length and diameter of asbestos and other fibers were measured. Elemental analysis of the nonasbestiform constituents was performed using energy dispersive X-ray analysis. Real-Time Monitoring The entire brake maintenance operation was recorded on videotape. Two Hand-held 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-optical system provides instantaneous measurements of total dust levels in mg/m^ at 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 in the operator's breathing zone and in the area beneath the vehicle's axle. Before each brake maintenance job, the HAMs were 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 25-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 real-time plot of the dust levels was made. By comparing the peaks from this plot with the video, work practices producing elevated dust levels can be identified. Ventilation Kurz Model No. 480 and TSI Model No. 1630 air velocity meters were used to 12 measure air velocities to determine flow rates and wind directions in the garage. Smoke tubes were used to assist in observation of general airflow patterns. 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 using a brake washer assembly unit. Each worker was videotaped during routine brake inspection and 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 "stop-action" techniques. Work analysis included breaking the job into general tasks which could be matched with airborne dust levels during brake inspection and replacement. Work tasks which could cause personal exposure 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 Real-Time Sampling Results Real-time total total dust data were collected using Hand-Held Aerosol Monitors (HAM's) connected to an Apple II Plus computer. Two real-time samples were collected: one alongside the personal sample on the brake mechanic, and the other just below the vehicle's axle. Real-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-five 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 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 real-time computer data, the instruments background level (0.05 millivolts) is used as the reference point at this facility. This background level is the HAM/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) of these dust exposures, relative dust exposures due to certain phases of the brake job can be identified and compared. Real-time data detected brief elevations of total dust during the removal of the lug bolts and the drum, and during the reinstallation of the lug bolts. The greatest potential asbestos dust exposure occurs during removal of the brake drums. Each drum contains ground-up brake shoe residue which is likely 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 job, the worker was exposed to elevated dust levels from 0.7% to 11.0% (averaging 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 bolts from the Wheels. These levels were up to three times the reference level on 38% of the brake jobs. When reinstalling 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 0.2% of the total time spent in loosening and tightening of the lug bolts. Removing the old and installing the new brake shoes resulted in slightly elevated dust levels, up to 1.5 times above the reference level, in 9% of the brakes replaced. For each brake job, the worker was exposed to elevated dust levels from 0.2% to 0.3% of the total time spent in removing and installing of the brake shoes. On the third brake maintenance operation, there were prolonged elevated dust exposures during the time it took to remove the lugs from two wheels. The dust levels were seven to eight times above the reference level and averaged 5.1% of the total brake maintenance time for two wheels on one vehicle. When the air-impact wrench was replaced, dust levels and exposure time both dropped, indicating a faulty air-impact wrench. Also noted was the cleanliness of the wheels, the amount of road dust on the rims. Of the forty wheels, 20% could be described as clean, 60% fair, and 20% 14 dirty. From the real-time data, there was no clear relationship between dust exposures and cleanliness of the wheel. The greatest potential to asbestos exposure is during the removal of the brake drum. This potential appears to be reduced when the cleansing liquid is allowed to flow between the brake drum and brake support plate before the drum is removed. The high dust level experienced during the removal and tightening of the lug bolts appears to be due more to the air-impact wrench than the road dust on the rim. One faulty or worn out air-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 real-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 new shoes. As a result, total dust levels were low or not measurable during 91% of brake shoe replacements. Air Sampling Results Individual filter sample results for airborne asbestos fibers are presented in Table A-l 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/cc, with only one sample above 0.004 fibers/cc. Source samples taken above the wheel (fender) averaged less than 0.002 fibers/cc; source samples hung over the axle and centered between the wheels averaged less than 0.002 fibers/cc; background samples collected at two separate locations in the garage averaged less than 0.001 fibers/cc; and outdoor ambient samples averaged less than 0.001 fibers/cc. 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 detection limit of 0.004 fibers/cc. Because personal sample concentrations represented exposures while servicing brakes, and this usually takes no more than 2 to 3 hours per shift, the mechanics time-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. All fibers identified as chrysotile or amphibole asbestos with an aspect ratio of 3:1 or greater were counted (fibers 0.25 microns and longer are included). A few samples contained fibers that were not identified (no I.D.), but could possibly be asbestos. 15 Table 1 Phase Contrast Microscopy Concentrations for 10 Vehicles (fibers/cc) 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 10 <0.002 <0.002 16 <0.001 <0.001 8 <0.001 <0.001 Table 2 TEM Concentrations for 10 Vehicle Brake Jobs (fibers/cc) Sample Type Number of Samples Arithmetic Mean Standard Deviation Range Personal Fender Axle Background Ambient 10 0.008 0.003 <0.006 - 0.013 10 0.009 0.012 <0.002 - 0.040 10 0.004 0.004 <0.002 - 0.016 8 0.002 0.001 <0.001 - 0.006 4 0.002 0.001 <0.002 - 0.003 16 The arithmetic mean TEM concentration (Table 2) for all personal samples was 0.008 fibers/cc, with a standard deviation of 0.003 fibers/cc. This concentration was higher than the background levels in the building (which averaged 0.002 fibers/cc), and the outdoor ambient levels (which averaged 0.002 fibers/cc). Source samples taken at the axle averaged 0.004 fibers/cc, while samples taken at the fender (above the wheel) averaged 0.009 fibers/cc. 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), M-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 1% 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. 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. Two of the brake drum bulk samples contained amphibole fibers. From 0 to 3% of asbestos fibers and bundles were longer than 5 microns. Three percent of the fibers from brake job No. 1 bulk sample were larger than 5 um. The remaining eight bulk samples contained 1% or fewer chrysotile fibers longer than 5 microns. The rafter sample contained 99% chrysotile fibers with 7% of the asbestos fibers larger than 5 microns. The 0SHA Standard or 0.2 fibers/cc (Action level 0.1 fibers cc) and the NIOSH recommended exposure limit of 0.1 fibers/cc 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 samples show that more than 85% of the chrysotile fibers counted using the ''A" rules would also have been counted using the "B" rules. Based on the levels measured by both PCM and TEM however, the mechanic's exposure in this study would be well below these recommended levels. V. CONTROL TECHNOLOGY Occupational exposures can be controlled by the application of a number of well-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 Brake Job Vehicle & Year Sample No. Table 3 Bulk. Sample Results Grids Examined Amphibole Number of Chrysotile and Amphibole Fibers* Z of Total Fibers Chrysotile and Amphibole Chrysotile and Amphibole Fibers* |5 um 1 Jeep 1976 2 9 No 83 83 3 2 " 1977 3 4 No 97 88 0 3 " 1977 4 3 1 116 96 0 4 1978 5 10 No 66 97 0 5 1977 6 4 No 115 97 0 6 1978 7 4 No 112 97 1 7 1981 8 10 1 41 100 0 9 1973 9 10 Ho 54 100 0 10 1974 10 10 No 19 86 0 Rafter 1 8 No 100 99 7 * Includes fibers, fibers in a matrix, and bundles. V 18 situations,. but their optimum application varies from case to case. The 'application of these principles are discussed below. Engineering controls The brake washer assembly unit is used at this garage to contain and collect all brake lining dust (including potentially hazardous asbestos fiber content). The unit (which is fully described in Section II) is used during all brake inspection, repair, and brake lining replacement. 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/cc, well below the current OSHA standard of 0.2 fibers/cc and the NI0SH recommended standard of 0.1 fibers/cc. Low fiber concentrations (by PCM) were also found for the source sample placed on the fender directly above the wheel. After completing servicing to the first wheel, this sample was moved to the fender above the other wheels so that this sample included dust emissions from all four wheels. The fender sample concentration for each of the 10 brake jobs was less than 0.002 fibers/cc. The other source sample, hung over the axle, showed concentrations of less than 0.002 fibers/cc for all 10 brake jobs. The importance of this source sample is that it shows dust fibers were not being propelled by the brake washer assembly unit liquid toward the other side of the vehicle. As noted 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. 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 urn 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/cc, respectively, for all 10 brake jobs. Fender sample asbestos concentrations were very low, ranging from the detectable limit of 0.004 to a high of 0.040 fibers/cc. The axle source samples were also very low, ranging from 0.004 to a high of 0.016 fibers/cc. Background and ambient asbestos concentrations by TEM averaged 0.002 fibers/cc. These low asbestos levels indicate that the asbestos in the personal and source samples was from activities such as brake servicing and not from outdoor sources or from resuspended dust in the garage. The sampling at the Nashville Postal Service garage was conducted in mild weather (October), with some doors open most of the time. Natural ventilation 19 Table 4 Work Task Analysis of Brake Inspection and Replacement Step Work Task Brake Dust Exposure Sources 1 Use pneumatic wrench to remove five lugs from wheel. Loose dust around lugs and tire rim. 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, loose dust from components 7 . Worker cleans axle surface. 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 clean, and put back on brake unit. 10 Wheel is put back on vehicle. 11 Wheel lugs are pneumatically tightened on wheel. Loose dust around lugs and tire rim. \ 20 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 exposure points while performing this task are also noted. The average work cycle time for a one-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 38.2 + 12.8 years. As a group these men had 4.0 + 1.9 years experience as mechanics, and performed 5.6 + 2.5 brake jobs per week. The other job duties included general maintenance, engine tune-up, 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 tool, 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: the use of a respirator, clean-up procedures and safety precautions, and not to use compressed air to blow out 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 X-ray as part of their physical examination. Analysis of workers with and without X-rays showed an age dependent pattern with all three workers who had X-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 leaving work. The U. S. Postal Service provides work clothes and laundry service for the regular work force. 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 for nuisance dust and the brake washer assembly unit when performing brake maintenance and repair. VI. CONCLUSIONS AND RECOMMENDATIONS The use of this brake washer assembly resulted in very low asbestos exposures, for the 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 P&CAM it239) of around 1 fiber/cc and time weighted average exposure of around 0.2 fibers/cc with dry brushing 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 belowthe 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 the chrysotile fibers counted using the "A" rules would also have been counted using the "B" rules. Since the TEM method is more sensitive, this allowed comparison between personal or source samples and background and ambient levels, all of which were quite low. 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-type 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 1% 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-time 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 Training in the operation and maintenance of this unit is important for developing good work practices which could reduce potential brake asbestos exposure. Mild weather with some of the doors open may have resulted in lower ambient levels than might occur during cold weather when the doors are normally kept closed. 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, 71:6; 1123:1142. 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. 22:261-269, 1965. 5. McDonald, A.D. et al. Epidemiology of Primary Malignant Mesothelial Tumors in Canada. Cancer 26:914-19, 1970. 6. Greenberg, M. and T.A. Lloyd Davies. Mesothelioma Register 1967-1968 Brit. J. Ind. Med. 31:91-104, 1974. 7. Lorimer, W.V., A.N. 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. 43:207-218, (May-June 1976). 23 8. 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. 38:492-500, 1970. 9. Davis, J.M.S., and S.W. Coniam. Experimental Studies on the Effects of Heated Chrysotile Asbestos and Automobile brake Lining Dust Injected into the Body Cavities of Mice, Experimental and Molecular Pathology, Vol. 19, pp. 339-353 (1973). 10. Koshi, K., H. Hayashi, and H. Sakabe. Biological and Mineralogical Studies on Serpentine Minerals in Heat Treated State, Ind. Health, Vol. 7, pp. 66-85 (1969). 11. Pott, F., F. Huth, and K.H. Friedricks. Tumorigenic Effects of Fibrous Dusts in Experimental Animals. Environmental Health Perspectives, Vol. 9, pp. 313-315 (1974). 12. 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. The Fibrogenic Effects of Mineral Dusts Injected into the Pleural Cavity of Mice, British Journal Exp. Pathology, Vol. 53, pp. 190-201, 1972. 14. Stanton, M.F., M. Layard, A. Tegeris, E. Miller, M. May, and E. Kent. The Carcinogenicity of Fibrous Glass: Pleural Response in the Rat in Relation to Fiber Dimension. J. Natl. Cancer Institute. 58:587-603, March 1977. 15. NIOSH. (1976) Revised Recommended Asbestos Standard. U.S. Department of Health, Education, and Welfare. DHEW (NIOSH) Publication No. 77-169, p. 93, December 1976. 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. 17. NIOSH Method 7400. (1984) NIOSH Manual of Analytical Methods, Third Edition Vol. 2, DHHS (NIOSH) Publication No. 84-100. 18. Burdett, Garry J., and Anthony P. Rood. (1983). 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REPORT NO. 4. Title end Subtitle In-Depth Survey Report: Evaluation of Brake Drum Service Controls at United States Postal Service, Vehicle Maintenance Facility, Nashville, Tennessee, Report No. CT-152-20B__________ 7. Authorts) Godbey, F. W., T. C. Cooper, J. W. Sheehy, D. M. O'Brien, H. D. Van Wagenen, J. D. McGlothlin, and W. F. Todd 9. Performing Organization Name end Addrese Engineering Control Technology Branch, Division of Physical Sciences and Engineering, NIOSH, Cincinnati, Ohio 12. Sponsoring Organization Name and Address -PBa8-16^19 J 5. Report Dete 87/08/00 8. Performing Organization Rapt. No. CT-152-20B 10. Project/Task/Work Unit No. 11. Contract(C) or Grant(G) No. <C) (G) 13. Type of Report & Period Covered 15. Supplementary Notes I 14. 16. Abstract (Limit: 200 words) The effectiveness of a brake washer assembly unit (Kleer-Flo Model LW-22 Rollabout) for limiting exposure to asbestos (1332214) during the servicing of automotive brakes was evaluated as the U.S. Post Office Maintenance Garage in Nashville, TN. A fleet of 575 Jeep delivery vehicles are serviced at this facility. Most of the vehicles had 13 or 14 inch wheels and 10 inch long brake shoes. Ventilation in the garage was minimal. During winter months, there was no provision for fresh, heated air from the outside. When the 14 bay doors were open in the summer, they provided good ventilation in conjunction with roof fans. One gallon of concentrated detergent, Greasoff No. 19, was used diluted to clean 40 to 50 wheels. Very low asbestos exposures were recorded when this washing assembly was in operation. Personal air samples for the brake mechanics averaged less than the detection limit of 0.004 fibers/cubic centimeter (f/cc) with only one sample above 0.004f/cc. Of the ten vehicles tested, fibers found in the drums were between 83 to 100 percent chrysotile (12001295), with two vehicles having 100 percent asbestos fibers The authors recommend showers for employees before they go home from work, a laundry\service to clean soiled work clothing, and further education concerning the potential hazards of this particular work. The authors conclude that use of this brake washer assembly resulted in very low asbestos exposures. 17. Document Analysis a. Descriptor* b. Mentlfien/Open-Ended Terms REPRODUCED BY U.S. DEPARTMENT OF COMMERCE NATIONAL TECHNICAL INFORMATION SERVICE SPRINGFIELD, VA. 22161 j NIOSH-Publication, NIOSH-Author, NIOSH-Survey, Field-Study, CT-152-20B, Region-4, Repair-shops, Fibrous-bodies, Dust-inhalation, Airborne-fibers, Air-quality-control, Air-sampling, Dust-control, Asbestos-dust c. COSAT! Fleld/Group lft. Availability Statement (Sh ANSI-239.18) 19. Security Cleaa (This Report) 20. Security Class (This Page) Se. tmiructlons on Rev.rs. 21. No. of Pages ji 22. Price Ml U-li" OPTIONAL FORM 272 (4-77) (Formerly NTlS-35) Department ol Commerce item w a s received ite m is d e fe c tiv e . it or d rr e e r iofracn f d s e m id ite ro v f p ionetr,ndrtoeerrtw,iuiliflrf tntbhheoee Reproduced by NTIS National Technical Information Service Springfield, VA 22161 This report was printed specificallyfor your order from nearly 3 million titles available in our collection. For economy and efficiency, NTIS does not maintain stock of its vast collection of technical reports. Rather, most documents are printed for each order. Documents that are not in electronic format are reproduced from master archival copies and are the best possible reproductions available. If you have any questions concerning this document or any order you have placed with NTIS, please call our Customer Service Department at (703) 605-6050. 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