Document dnmde54xewDKnpnRBDnryR89

<>r, u re Vo a sc cat os fibers wh<.1 c drilling ebony power Cases 4S102-1 A sbestos 481QO-1 Beil Laboratories June oO ' -ci. Cl o 3 MEMORANDUM FOR RECORD In a letter of April 26, 1974, J. P. Dunn, M.D. Assistant General Medical Director, WECo., requested a study be made of the exposure to asbestos fibers of an Individual drilling ebony power board. On May 22, 1974, the Rolling Meadows, Illinois facility of WECo. was visited for the purpose of evaluating the exposure of an employee drilling ebony power boards in a simulated central office environment. Arrangements were made by Mr. A. A. Skriptunas, WECo. Rolling Mc-adowc, to set up a simulated central office installation and to provide the material and the installer. Mr. V. Hudson, an employee at Rolling Meadows, had at one time worked as an installer in central offices and had actually made installations on ebony power boards on numerous occasions. He stated that the drilling of holes in ebony power boards to accept additional fuse posts was a very brief and infrequent operation. This operation was restricted to midnight to 6 a.m. because of the possibility that operating power could be lost in the office due to an accident on the power board. Thus, the typical exposure In a workday would be one five minute drilling period followed by a brief cleanup. An installer might be expected to do this job once or twice a year. No other reason was given for drilling ebony power boards. The ebony board is described in "Impregnated Asbestos Composition Panels," Western Electric Co. Material Specification 7:221, Issue 5, February 28, 1974 , "1. Scope. The material is an asbestos and Portland cement mixture press._ Into a hard, uniform panel and impregnated with a titunir:dielectric. It is intended for use as a panel for eie : crical switchboards." According to Miss Celine 7aul, Manufacturing Engineering, Chicago, the panel containt to Ida asbestos. 003637 I .1 j r." a:' performed in aeeo-Muncc with the OSH j-.roc-. :..rc outlined in Appendix J Air f amolir.:- thods , pa.yr: VTTJ-i to V' TI-3 (tee attached refer'.nee) Air was drawn through a 37 run diameter Milliporo filter disc K,V.;G 03/' AM lyre A white griUdoa filter mounted in 3. prea..:;-:tbied monitor. The rate of air flow was calibrated at 1.0 liters per ornate determined by use a one liter bare t a a primary standard before and after the survey. Two MIA Monitairc Samplers Model S with Approval No. 2F-200i| issued by the U.C. Bureau of Mines and equipped with a pulsation dampener were used as air pumps. The sampler was attached to the be]c of the employee and was connected to the monitor via a clear plastic tube. The proassembledmonitor containing a Mi11ipore filter was opened immediately prior to sampling and was pinned to the shirt of the employee. The filter assembly and air pump can be seen in some of the illustrations included in this report. Sample Analysis All samples and a blank were submitted to George D. Clay con and Associates. 25711 Southfield Road, Southfield, Michigan, for evaluation of the fiber count using the recommended method page VIII-6 of Appendix I of the NI02;M document. The following are the details of the method they use: "The sample preparation of Millipore Type AA (membrane) filter samples consists of ousting out a preehaped section, placing it on a glass slide, dissolving it with a drop of clear in solution and finally covering it with a cover glass. The ~ clearing solution is a 1:1 diethyl oxalate-dimethyl phthalate mixture containing 0.1 gram of pure membrane filter material per milliliter of solution. The filter material is added to reduce the rate of solution of the sample filter and thus minimize the migration of dust particles. As soon as the sample is cleared completely it is ready for examination." "The fiber counting is accomplished using a UOY. phase contrast objective and periplan 10X eyepieces equipped with a Porton reticle. The Porton reticle has a series of calibrated circles tc which each fiber is compared. A minimum of "0 fields is examined to assure a representative count." `'Criteria for a re com: .ended standard... . Occupational Exposure to Asbestos, Rational Institute of Occupational Oafoty and Health 1972. CONFIDENTIAL 003638 3 Tcs t r ro cedarc A typical central office ebony power board panel is illus trated in Fir;. 1. The job Involved an employee drilling a act of holed in such a power board for installation of additional fuse posts. The tests were conducted on a simulated central office frame on which were mounted three separate ebony power board strips. The strips consisted of (1) a 3 inch wide, 1 inch thick "hard" ebony board H6 inches from the floor (Fig. 2), (2) a 3 inch wide, 1 inch thick "hard" ebony board 23 inches from the floor (Fig. 3) > and (3) a 3 inch wide, 5/8 inch thick "soft" ebony board 6l inches from the floor (Fig. 4). All three boards were bolted to a plywood back to simulate the actual installation. They had been randomly selected from a pile of scrap board and no information on the spec ifications was available. The determination of "hard" or "soft" was made by Mr. Hudson based on his experience. Mr. L. J. Eykstra, Manufacturing Engineering, Chicago, Indicated that 1 inch thick "hard" ebony board is no longer stocked and the only thickness currently available in "hard" or "soft" is the 5/8 inch thickness. The thickness of ebony board available are 3/8, 1/2, 5/8, 1, 1-1/2, and 2 inch "soft" and 5/8' inch "hard". The test room was "L" shaped 32 feet by 8 feet with a pro jection 14 feet by 14 feet and a height of 13 feet and normally functioned as an enclosed storage area for the loading dock. There was no air supply or exhaust system for the room, thus simulating a worse case. Mr. V. Hudson did all the drilling using a hand held 1/2 inch Thor drill at 500 R?K. Breathing zone samples were collected during a 15 minute period and included the actual drilling cycle (cleaning out of the holes and drill bit, checking the hole diameters and sweeping up the floor) and the time interval following the drilling during which -the holes were checked and prepared for installation. The drilling 'was completed in 5 minutes or less, but the samples were continued for 15 minutes as recommended, by NIOSHl. The tests were repeated without changing the tes4' conditions or ventilating the room. Each breathing zone sample represents cr.e complete drilling operation and simulates the extent of an installers exposure in the field. Continuous room air samples were collected during the entire tests for a total of 4 hours. Re cults The results are reported in Table 1. The general room air cons _ r.ti at ion of airborne fibers greater than 5 micrometers r r" *vV. \*r >*. 7 3 4 Ct 003639 - 4- per cubic centimeter was 0.Oil for the first hour, 0.016 for the second hour unci 0.011 for the third and fourth hours. These samples were collected at nose level. The filter can be s< ?n on the stand behind the man drilling in Fig. 2, The breathing some samples collected during actual work operations are samples Nos. 2, 3, 5, 6, and 8. The con centration of airborne fibers greater than 5 micrometers per cubiic centimeter was 0,04?, Q.0&Q, 0.044, Q.O67, and 0.097. Sample No. 8 was the last sample of this series and was collected while sweeping up the debris resulting from all the previous drilling. Conclusions The samples collected r.ere designed to evaluate conditions found at the employees breathing sone during drilling and cleanup and in the general room air. All samples were within the 1equirements of the Occupational Safety and Health Standards, Federal Register, Vol. 37, No. 202, page 22142, paragraph "1910.93a Asbestos. (a) Definitions (2) Standard effective July 1, 1976. The eight hour timeweighted average airborne concentration of asbestos fibers to which any employee may be exposed shall not exceed two fibers, longer than 5 micrometers per cubic centimeter of air,. . . . " Based on the results reported it is concluded that this simulated operation was completely within the OSHA require ments. It is recommended that this be verified in actual central office editions. . MH-8 4 35-WJS-el Copy to Mr. J. P. 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