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PLAINTIFF'S EXHIBIT subiect: Evaluation of Employee Asbestos Exposure During Brake Work Operations Case 48106-3 Bel laboratories <iate February 8, 1978 1,or V. R. Cohen R. Deitchman MEMORANDUM FOR RECORD INTRODUCTION The hazard of exposure to airborne asbestos during the changing of brake linings and clutches has been recognized for several years. (Hickish and Knight, 1970; Hatch, 1970). Mizutani et al. (1973) have reported that chrysotile In brake materials displays structural strain and substructure fragmentation caused by shear during braking processes. Material fatigue results from this shear strain and along, with binder pyrolysis can produce disintegration of brake linings liberating chrysotile asbestos fibers. (Rohl et al, 1976). The presence of chrysotile in brake drum dust has been demon strated by X-ray diffraction, transmission electron microscopy, selected area electron diffraction and electron microprobe analysis (Rohl et al, 1976). In these studies the percentage of chrysotile by weight ranged from 2-15% with an average ranging from 3 to 6%. Other components identified in brake drum dust Included lead compounds, quartz, calcite, mica, clays, barite, graphite and alpha-iron particles. The three major constituents of brake linings are binders, fioer reinforcers and property modifiers. The binders are primarily phenolic-type resins noted for high binding effi ciency and ability to withstand pyrolytic breakdown. The modifiers cover a wide range of materials and are used for a number of purposes. They are used as lubricants to reduce the coefficient of friction along the brake surface (lead compounds) and as agents to increase the coefficient of friction and enhance the action of the brake shoe (brass chips). Modifiers are also used as internal abrasives to help recon-* dition braking surfaces and remove deposited decomposition products (e.g. rottenstone, quartz). Chrysotile asbestos is the major fiber reinforcement material and comprises from 40 to 50 percent of the brake. In the past, methods of cleaning out brake drums have included blowing with compressed air, dry brushing and impacting the CONFIDENTIAL 003929 2 drums against the floor. -These methods have been associated with high airborne asbestos fiber exposures. Peak exposure levels reported by the National Institute for Occupational Safety and Health (NIGSH, 1975)during the blowout of auto mobile drum brake assemblies, beveling of new truck brake linings and the grinding of used truck linings gave peak exposure results of 10.5, 37-3 ana 3-75 fibers per cubic cent im.eter. To reduce the hazard of asbestos fiber inhalation by garage workers ir. the Bell System, two industrial vacuums were pur chased*. Studies were performed at Bell Laboratories and thre* operating company garages to determine employee exposure to asbestos during brake work operations. The industrial vacuum cleaner is modified to support a efficiency particulate air (HERA) filter. Caution and warn: labels are attached to the vacuum cleaner alerting vhe opens to precautions to be taken when working with asbestos, C> a vacuum cleaner is mounted on a th'-'ee wheel platform to tort at1~. The vacuum cleaner nose- has standard domest name s. svapt and recommendations Em.pl.vee asbestos exposure was evaluated during traxe work iz~ eracicr.s using a vacuum cleaner. Two operating telephone com panies were chosen for field trials. Employees at Michigan Red were sampled twice, first a month after the vac um. was received and three months later. Chesapeake and Potomac Tele phone Ttmpany employees were sampled two months after initial use :N the vacuum, cleaner. Results from these studies showed all personal exposure levels to range from below detectable limits 'less than 0.01 fibers per cubic centimeter) to 0.0? fibers per cubic centimeter. The present Occupational Safety and Health Administration (OSHA) Standard for asbestos exposure is I fisers per cubic centimeter on a time weighted average. However, a new National Institute for Occupational Health Criteria Document calls for an asbestos standard cf 1.1 fiters ter cubic centimeter on a time 'weighted basis. Camples were analytes by either phase contrast microscopy, scanning electrcr. mirrrsccpy, or transmission electron microscopy. ire garare environmental sample indicated a reorder of small ashes-*s fibers appearing to be Forsterite, the decomp os iti;r prod--- :f chrysotile asbestos crakes. The health hazard cf T.-s- --all fibers is unclear. * CONFIDE?1-21 *5 J ^ .i1 i 3 4 r-'A, 1 _ uurr. Cleaners, Node! do 003930 Respirator use is not necessary when performing brake cleanin work with the vacuum cleaner. A single use respirator is supplied for use during vacuum filter changing. The res pirator is then disposed of in a properly sealed bag. The following are recommended: 1. At the present time NIOSH is funding a study to evaluate asbestos vacuum cleaners for brake work. The study is under contract to Texas A&M University and results should be available by late 1978. NIGSH may at some time consider certifying vacuums cleaners for use in garages. This Texas A&M Study will include an evaluation of the vacuums cleaners in terms of collection efficiency of asbestos fibers. The Bell System Study only involved evaluation of the brake work operations, not the vacuum cleaner alone. The results of this NIOSH Study should be incorpor ated into Bell System vehicle maintenance opera tions . 2. Another alternative method tc clean brake assem blies is u:e of a solvent with a collection unit. These units are less expensive than vacuum cleaner systems but have not been evaluated in terms of Bell System employee exposure. A solvent unit should be evaluated in an operating telephone com pany garage. 3. In order to function properly the vacuum cleaner requires some changes including new vacuum hcse attachments. Formulation cf information and docu mentation outlining procedures for brake work with the vacuum cleaner is necessary. In conjunction with the vacuum cleaner, a crake assembly cleaner (such as those manufactured by ?er-Lux or BrakeVac) may be necessary to sufficiently clean the brake assemblies. The brake assembly cleaner fits snugly over the wheel and uses compressed air to clean the brake assemblies. An evaluation from a vehicle maintainence and industrial hygiene view is necessary with these systems. fc. To comply with OSHA requirements, medical and environmental monitoring may still be necessary fcr employees exposed to asbestos fibers during brake work op? rations. Empityees monitored in this study should be informed cf their air sampling re sults. METHODS The asbestos samples were collected using the procedures outlined both by the National Institute for Occupational Safety and Health (NIOSH) and the Occupational Safety and Health Administration (OSHA). The procedure involves col lection of the airborne fibers on a small filter, with later analysis using phase contrast or electron microscopy. The filters used for collection of the samples were either 37mm Millipore cellulose ester filters or 37mm Nuclepore polycarbonate filters. Both filter types have nominal porediameters of 0.8 micrometers (pm) and were used open faced. Air was pulled through the filters using battery powered sampling pumps manufactured by Bendix and MSA at 2.0 liters per minute. The pumps were calibrated using the soap bubble flowmeter technique. An Anderson high volume pump was used to collect peak airborne samples during the actual vacuuming of the brake drums. The flow rate was 25.5 liters per minute. A variety of analysis techniques have been used to identify asbestos fibers and determine their concentrations in air. These include optical microscopy, electron microscopy, and X-ray diffraction analysis. Asbestos fiber identification and quantitation in occupational and environmental air samples is difficult for a variety of reasons: 1. Asbestos fibers are generally present in low mass quantitites even though fiber number concentrations may be high. 2. Many instrumental analytical techniques cannot differentiate asbestos fibers from their nonfibrous mineralogic polymorphs. This is the case with light microscopy and thus, electron microscopic methods are necessary to be certain fibers are truly asbestos. 3. Many airborne asbestos fibers are generally below resolution limits of the optical microscope (phase contrast). These fibers may only be detected by using electron microscopic methods. U. For identification of the various asbestos fiber types by electron microscopy, electron diffraction and micro chemical analyses must be performed which require extensive in strumentation and analysis time. The cellulose filters in this study were analyzed using phase contrast microscopy while analysis of the polycarbonate filters was performed using electron microscopy. 003932 -5- Light microscopy was completed by Ms. V. R. Cohen and Mr. C. Lichtenwalner of the Bell Laboratories Environmental Health and Safety Department. The light microscope uses phase con trast to identify fibers greater than 5 um in length and a greater than 3:1 aspect ratio. P. Beth transmission and scanning electron microscopy were used for asbestos fiber identification and quantitation. In addi tion to morphologic observation, selected area electron dif fraction and energy dispersive X-ray analysis were used. Transmission electron microscopy will yield higher resolution than scanning electron microscopy, however, scanning will cover a larger optical field for analysis. Transmission electron microscopy was performed by McCrone Associates, Inc., Chicago, Illinois. EMV Associates in Rock ville, Maryland performed the scanning electron microscopy. In order to test the performance of the filtration system, a modification of standard procedures for evaluating the perfor mance of high efficiency particle filters and clean rooms was attempted. An aerosol generator capable of producing 0.3um diameter mean particle size dioctyl phthalate was used to pro duce an aerosol for detection with a Virtis Particle Counter. Unfortunately, it was not possible to test the efficiency of the filtration system because of the high background particle concentration and the geometry of the vacuum system. A rela tively elaborate test fixture and environmental chamber would be required to test the efficiency of the filtration system. This work was performed by Mr. C. P. Lichtenwalner and Mr. R. Deitchman of the Bell System Services Group. RESULTS Table I shows the results of air sampling for asbestos at the Livonia, Michigan garage of Michigan Bell on August 30, 1977 by Mr. R. Deitchman of the Bell System Services"Group. This was the first attempt at field sampling of asbestos exposure of employees while using the vacuum cleaner during brake work. All samples were analyzed by transmission electron"microscopy and all results were below detectable limits. The area sample in the garage, however, revealed an extremely large number of fine, single fibril, fibers which appear to be Forsterite, the decom position product of ehrysotlle asbestos on extreme heating which might originate as brakes are applied. These fibers were in general less than 0.5 ,,n with the size distribution between 1.1-1.0 um. Sampling during brake work using the second vacuum cleaner was completed on October 31, 1977 at a C & P Telephone Company CONFIDENTIAL 003933 6- - Garage in Washington, D. C. by Ms. V. R. Cohen ana Mr. W. J. Schreibeis of the Bell System Services Group. Results are shown in Table II. A high volume Anderson pump was used to collect peak samples to gain greater accuracy and lower de tectable limits. Samples were analyzed by light microscopy and transmission electron microscopy. On November 14, 1977 additional sampling was completed by Mr. W. J. Schreibeis and Mr. R. Deitchman of the Bell System Services Group on the first vacuum cleaner which had been moved to the Romulus Garage of Michigan Bell. This sampling was to check employee exposure to asbestos during brake work after the vacuum cleaner had been in field use for three months. Samples were analyzed by scanning electron microscopy (3EM) and light microscopy. The SEM results from samples taken at the vacuum exhaust, using the Anderson high volume pump for collection, are all below the lower detectable limit. The long term, high volume samples of the background asbestos level analyzed by SEM shows one chrysotile fiber for a concen tration of 0.0005 fibers per cubic centimeter. Light micro scopy results of asbestos exposure showed levels ranging from 0.02-0.06 fibers per cubic centimeter. V. R. Cohen Industrial Hygienist VRP MK-7885-pQ -cm R. Deitchman Industrial Hygienist Copy to R. L. Beach - AT&T C. Buck, M.D. - MBT E. Burgess - C&P N. J. DeCapua - AT&T J. M. Degen - AT&T R. Jones - MBT W. J. Schreibeis - ETL R. W. Stone, M.D. - AT&T G. M. Wilkening - BTL I | CONFIDENTIAL 003934 REFERENCES Hickish, D.E. and Knight, K.I. (1970). Exposure to Asbestos During Brake Maintainance. Ann. Occup. Hyg. 13, 17-21. Hatch, D. (1970). Possible Alternatives to Asbestos as a Friction Material. Ann. Occup. Hyg. 1_3, 25-29. Mizutani, Y., Qbara, H., and Nakajima, K. (1973). Study of Friction and Wear of Resin-bonded Asbestos. 387-392. X-ray Wear 23, " Rohl, A.'J., Larger, A.M., Wolff, M.S. and Weisman, I. (1976). Asbestos Exposure During Brake Lining Maintainance and Repair. Env. Res. 12, 110-128. NIOSH Issues Asbestos Dust Alert for Workers Exposed Servicing Brakes; Occ. Safety and Health Reporter, BNA, 5, 3A8-A9, 1975. CONFIDENTIAL 003935 I A sbestos Samples C o lle c te d In a M ichigan B e ll G arage, L iv o n ia , M ichigan August 30, 1977 VH O *5 5S-* i* s 5 *4 Si! a S3 5- Ut aHi I as av a S3 mAQ aj 1H3 o-> *-ov. A U*-* i W &* A K-i Co *.. H A U44* c3H 4 *5 n a Gioi -Ch H3 CO *is i ru4t> <4CBno<>L ra. W ^ T3 fc c x: 3 a f* * Sfc tSf. I **4 G O *1 f* *J C. V Gw WO CC 130 U(i-4/ O O TS CL, r-t A ntrUu ^UtCi ft tfl<< 3 t. hh .Cchi W 0) -s 'CONFIDENTIAL & o O S c HO>i d * .r4i f-i 003936 u *o -* o p c. >* p H s S3 3 3 A sb e sto s Sam ples C o lle c te d I n C. & P . Co. G arage 1120 F i r s t S t r e e t , NE, W a s h in g to n , D.C. m a o *4o1 P fc. otC--N- 2 0 "v. it (ft P J- >, & m 8 \> iOTv CU OO CK O o -3 o do o o fPt no no OJ H co no O OJ 3 -a O r4 CM 0j <n CU 8 i0r0\ ml/\ CM rH ca ort it P P3 b3. a > B ca cOo Cow 0C 5* * i* 36 <auH o .ev1 t:ii Uc:'iX ;*t i e! f.-s aVt. --o\' u3 uc c u JrJ U0t Ho V. |*I rft.t O S..- o CPU. I CONFIDENTIAL --Te U.' C-- t> Uv> t r. l. r .. (A Ui (< i c\t it u, c a. ;< i 3 3 P lA *C ": `v, u ttL- _* Vi p* it u i.i * P i> bfl P CC )Cb <u0J Cj*-* C *7 it W O 3 CU i* c <n t} t? t-* u cu o i O 3G C i 3 L. O eit O> Oft. 4 4c. 003937 s 5*> s K *> S 4 -n* O tt-S. <PP IIAs Si! c 55 3 5 5 10 CO Ua J ao io o B3 0Vfc. tC H .Of %2 5 a Is ft* 4/ t) Q X> 3qM. Vn St r-l J O -H > r-i 8 m i/\ oH Ho oo 8S oo s d 8 V fcrt 33 w a w T> S 3$ (I k6l)w t- } t0- V-t a p fa. fc'iD E *u& CONFIDENTIAL * S u3 TuI3 si x* r. a: u 3 u ,o p *** C! ,\i C nco au R> - Vc n u. --* cc u ., o r? s 'v P cI sci t) >p .o >uS C T33 T? l ;nOa Sip ni: t>i to d c *;.* a -phV aI:I e s: u. aQrt *i;>.' ut-jj. OV {--C] tf) tU... 4- *J nO a >. :o* cc:a; r-4 r* V 0. . It It II :i K:i 003938 7 Personal Sample employee breathing zone area during actual spray operations with Amrnco Brake Washer System 13 31 0.28 13 31 BDL (0.01) 8 Hour Time Weighted Average Exposure for Rick Malinowski 480 0.06 OSUA Standard 480 2.00 LH Light Microscopy SEM = Scanning electron Microscopy HDL = below Detection Limit (Lower Limit of Detection) LM SEM LM LM CONFIDENTIAL 003939