Document M4NnBE2z3w9OKkK18nV8XbVba
PLAINTIFF'S EXHIBIT
suBiect
Evaluation of Employee Asbestos
Exposure During Gara"' Work Operations at Pacific Telephone .ompany
Case 48106-3
Bell Laboratories
January 24, 1979 Uorr R. Deitchman
MEMORANDUM FOR RECORD
To reduce tne hazard of asbestos fiber inhalation by garage workers in the Bell System, an industrial vacuum was evaluated for use in brake work operations.* During a meeting with AT&T motor vehicle personnel, it was determined that Pacific Telephone had purchased and was presently using a solvent spray system and an industrial vacuum with a lower flow rate than recommended by AT&T to clean brake assemblies and drums and in clutch work operations.** It was requested that the Bell System Services Group at Bell Laboratories evaluate employee exposure to asbestos during work operations with these systems.
Summary
Un December 4 and 5, 1978, employees performing brake and clutch work operations at Pacific Telephone garages were sampled for asbestos exposure. Tne vacuum and solvent spray system used to control asbestos by Pacific T> lephone was evaluated and found to be compatible with AT&T requirements. Samples were analyzed by phase contrast microscopy and transmission electron microscopy.
Recommendations
The following are recommended as a result of this study:
1. The combination vacuum and solvent spray system results in a
low level of asbestos exposure to employees performing brake
and clutch work operations. Its use is compatible with the
requirements outlined in AT&T General Letter 78-18-045
{Transmits further rcihaeeftdatiafts
{irseedurea fa? ^rateesiaj
employees from excessive exposure to airborne asbestos
* Memorandum for Record, "Evaluation of Employee Asbestos Exposure During brake Work Operations," February 8, 1976.
** Ammco Solvent System and Pullman Vacuum Model JB-75R.
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subject; Asbestos Exposures During Brake Changes. Case: ^488106-3
Bell Laboratories
March 30, 1977 rom, Qm D. Kenney
MEMORANDUM FOR RECORD
Introduction
Measurements for asbestos we re taken at three different garages in the Miami District on December 1,2, 1976. In addition, measurements for lead, tin and copper were taken in one garage where a worker was welding and grind ing on a truck which was undergoing extensive bodywork.
Procedures
The asbestos samples were collected using the procedures outlined both by the national Institute of Occupational Safety and Health (UIOSH) and the Occupational Safety and Health Administration (OSHA). Basically the procedure Involves collection of the fibers on a small filter, with later analysis using phase contrast or transmission electron microscopy.
The samples for metals were collected In a similar manner. The filters used for collection of the samples were either 37 mm Millipore cellulose ester filters, or 37 mm Nuclepore polycarbonate filters. Both filter types have nominal pore diameters of 0.8 micrometers Cum).
Air was pulled through the filters using battery powered sampling pumps manufactured by Bendix. The pumps were calibrated using the soap bubble flowmeter technique.
The cellulose filters were analyzed using phase contrast microscopy while analysis of the polycarbonate filters was performed using transmission electron microscopy. Analysis for the metals was performed using the procedure of atomic absorption spectroscopy.
Background
During the course of this survey measurements w.-^e taken at three different garages. Rough sketches of the garages are attached.
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The main jobs being performed at garages 1 and 3 during the time measurements were being taken was annual pre ventive maintenance examinations of the vehicles. These include visual examination of the brake linings with replacement if necessary. At garage #2 welding, torching and grinding was being performed on the vehicles as well as the annual preventive maintenance examinations.
In all cases the vehicles being examined were 3/4 or 1/2 ton vans. In addition, once the brake drum has been pulled the drum and backing plate were cleaned by blowing out the dust using compressed air. The total time it took to check the brakes and mount new linings, if necessary, was 40 to 60 minutes per truck.
Results
The results of the phase contrast analysis are presented in Table I while results of the electron microscopic analysis are presented in Table II. Table III presents the results of the metal analysis.
Briefly, the results of the metal analysis indicate that during the operations of grinding, torching, and -welding insignificant amounts of metal fumes and or dust are generated. The levels measured were well below the appro priate OSHA standards for lead (200 yg/m3), tin (2000 yg/m3), and chromium (1000 yg/m3).
The results of the phase contrast microscopy analysis, presented in Table I, indicate that a definite exposure to asbestos fibers occurs during the operation of changing brakes. Three of the samples, one taken for a period as short as 12 minutes, had dust concentrations too heavy for an accurate count to be performed. The remaining personal samples gave values between 0.16 and 0.24 fibers longer than 5ym per cc of air. These values are elevated over the one ambient sample of 0.02 fibers/cc and the blind blank with an assigned value cf 185 L of <0.015 fibers/cc.
The results of the electron microscopic analysis are presented in Table II. They indicate that of the five general air samples collected, including the ambient, asbestiform fibers >5ym in length were detectable on only one sample; on this sample the concentration was 0.24 fibers >5 pm/ec.
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The one personal sample analysed by electron microscopy indicated an asbestos concentration of 1.04 fibers >5pn/cc during the eleven minutes necessary to blow out the brake drums. This level indicates that an occupational exposure to asbestos does occur during the blowing out process, a conclusion that correlates with the phase contrast microscopy results. Summary As a result of these measurements it is evident that an exposure to asbestos fibers occurs during the operation of inspecting and/or changing brakes. Consequently, where possible, engineering means to control the exposures should be investigated. In addition, the employees should be afforded medical examinations where possible.
Attachments Tables I, II, III Copy to B. M. May - A.T.&T.W. J. Schreibeis - BTL R. V/. Stone, M.D. - A.T.&T. G. M. Wilkening - BTL
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