Document rek3D88KZxmZ7b5DB4bJyw5EE

THE ACTUAL CONTRIBUTION OF AIRBORNE ASBESTOS FIBERS mm. OCCUPATIONAL EXPOSURE flE BT-STABDERS SKT.KCTTO PROCESSING fiZ ENCAPSULATED ASBESTOS BASJCEIh SCRIBING OF GASXET MATERIALS CARL A. MANGOLD, CZB ENVIRONMENTAL CONTROL SCIENCES, INC. BELLEVUE. WASHINGTON JANUART 1989 ABSTRACT Asbestos containing gasket stock can be Barked using a scratch awl or a scribe in preparation for cutting a gasket-. This is an operation described by sone workmen that handled asbestos gasket aaterlals In the course of their work and when new pre-cut gaskets or gasket cutting tools were not readily available. New Garlock Znc. gasket material, Style # 900/7735 containing about 70S chrysotile asbestos was scribed'in preparation for gasket cutting. Two gasket stock pieces were narked with the scribe each hour for 8 hours to sisulate the actions of a workman preparing gaskets throughout the work day as needed, or 16 gaskets. The air samplers placed on the operator and at 5 and 10 feet away from the operator recorded the release of chrysotile asbestos fibers in the air from this process. The operation was conducted in a clean room and low ambient levels of natural asbestos. The results showed that; 1. The electron microscopy analyses for total chryMtHe fibers averaged .002 structures/cc.'Structures/ cc is approximately equal to fibers/cc. 2. The electron microscopy analyses for chrysotile asbestos fibers greater than 5 micrometers in length and less i than .25 micrometers in diameter were compared to the phase contrast microscopy method. The results showed that there were no chrysotlle asbestos fibers present greater than 5 micrometers In length at concentrations above the lower level of detection of .002 structures/cc. This Is a method of verification of the phase contrast microscopy method. 3. The phase contrast microscopy analyses revealed that the average concentration for fibers greater than 5 micrometers In length was .003 flbers/ce. The personal sample of the operator using the scribe to mark gasket materials was .005 flbers/cc. The phase contrast microscopy method Is the only one specified for analyses In the Federal standard. The eight hour time-weighted average to the operator and to those of a by-stander In the enclosure are a fraction of the permissible exposure limit of .2 flbers/cc. TABU or COflUR ABSTRACT SABLE OP CONTENTS ' BACKGROUND ENVIRONMENTAL EXPOSURES VOLUME OF ASBESTOS USED INSHIPYARDS EXPOSURES OP THE CONSTRUCTION AND SHIPYARD TRADES CURRENT ALLOWABLE LEVELS OFEXPOSURE ' CONTINUING EVALUATIONS U.S. NAVY GASKET REPORT VERIFICATION OF THE NAVYGASKET REPORT THE DILEMMA EXPERIMENTAL DESIGN REFERENCES RESULTS AND CONCLUSIONS 1 1 2 6 ? 9. 10 11 13 15 17 21 24 1 1..BACKGROUND: Asbestos Is one of the aost plentiful, useful, end cheep Industrial minerals. Because of its high thermal stability and resistance to corrosion it appears in aore than 3,000 manufactured goods in the United States. Zstlaates are that at least 30,000,000 tons have been used in construction and aanufacturlng since the year 1900. This common use of asbestos has led to the exposure of Billions of Aaerlcans at levels that Bay have a significant iapaet on their health. Today, large nuabers of Aaerlcans are exposed to asbestos in Industry as well as the environaent where it occurs naturally. Most environaental exposures oeeurs in our cities, near industrial coaplexes, from soil high in asbestos content, in the water, and in the air froa these sources. Therefore, aost Aaerlcans receive at least soae regular low level exposure throughout their llfetlaes. In 1980, Dr. Churg (1) determined that aost city.dwellers retain a considerable aaount of asbestos in their lungs in soae state of clearance. The retained aaounts can be in the Billions of fibers just from living and working in the city where low level exposures to asbestos is coaaonplace. The concerns about the role of asbestos in the development of a lung disease : aabestosls, began in. the United States in the 1930's and progressed slowly as more was learned about the pathogenesis of the disease. Most of 2 * the attention was centered on disabled workers with obvious work-related exposure patterns involving exposure to the raw fibers of the various forms of asbestos used commercially. Few, If any, controls were followed so that tiae and intensity factors led to dose levels that precipitated various degrees of asbestosis. This continued until the I960's when signs of asbestos-related cancers began to reshape thinking and aetion about the occupational exposures to asbestos. Today, the exposures of workers to asbestos have been markedly reduced through various aeans of voluntary controls and legislations that led to the first Federal standards in 1972. Since that tiae the. permissible exposure levels of asbestos have, been reduced through the regulatory processes in the Dnlted States. In 1964, Karr (2} concluded that asbestos-related disease was an important problem among Insulators working in Naval shipyards. Bis assumptions were correct; however, the methods of assessment weakened the conclusions. Pioneer work was begun at Puget Sound Naval Shipyard (PSNS) in 1965, culminating in a conclusive report of exposure levels and medical findings by Mangold, Beckett 9 Bessmer (3,4). Most of the attention was directed at the products and the ' operations that produced high-level exposures to asbestos workers and associated trades, and because of the large volumes of asbestos used- annually-"in the shipyard. The conclusions were that the threshold limit value (TLV) 3 4* was still too high at 5 millions of particles per cubic foot (MPPC7), equivalent to about 50 fibers per cubic centimeter, and that intermittent peak exposures were far sore' iaportant that previously recognized. Both conclusions have been corroborated by sore recent literature. About 1964, Sellkoff (5,6) and-others reported the association of exposure to asbestos with asbestos-related cancers and the effects of ssoking. In 1976, Or. Selikoff (7) and a team of scientists published a protracted study of asbestos-related diseases which defined the latent effects of exposure and probable' dose-response relationship based upon tise and intensity of exposure. The sodel foraulated from high level exposures was extrapolated to all levels of exposure however so snail. But, J.E. Craighead, et.al. (8), M.R. Becklake (9) and W.J. Nicholson (10) all raised reasonable questions about the validity of the straight line approach because of the latency factors and ill-defined responses to low level exposure. Nicholson (10) further observed that the long lapse tine fron exposure to the onset of asbestosls, or asbestos-related cancers, creates difficulties in attempting to establish the true dose-response relationship. And, the diseases today were from decades past when few measurements of asbestos concentrations in the breathing zone of workers were made, exposures were high, and controls few. - ' '' Since that time Or. Churg (1) has described the 4 relatively high levels of asbestos fibers in the lungs of city dwellers not occupationally exposed. This suggests a sigmoid, or NS" shaped curve, so often found where a lower no-effect level Is reached. Otherwise, Billions of Americans receiving dally exposures to asbestos from the environment at low levels should show significant asbestos-related disease. They do not. Therefore, the assumptions that all levels of exposure have the same risk through the straight line dose-response model Is extreme and without proof. It Is based upon extrapolation and assumption. The Occupational Safety and Health Administration (OSHA) used those assumptions In the 1972 Federal regulation for occupational exposure to'asbestos (11) and subsequent downward revisions. In addition, they have made the assumption that all forms of asbestos, namely Chrysotlle, Amoslte, and Crocldolite, and sore recently less used commercial forms all produce asbestos-related disease at the same levels of exposure. More recent studies In 1988 by Dr. Churg and others (12,13) show that the potency of the various forms of asbestos are different related to the cancer producing effects. However, OSHA treats them alike; as does the Environmental Protection Agency (EPA) for regulatory control purposes. *, 2. ENVIRONMENTAL EXPOSURES: The amount of environmental exposure to natural forms of asbestos In the United States 5 * is substantial. Asbestos, mainly Chrysotilt, it common to the ambient air In the environment especially near mountainous regions In the United States. There are 22 States with major asbestos outcroppings that contribute substantial amounts of asbestos to the air, water, and the eroded soil. Many major cities, as Seattle, Nashlngton aay use drinking water for the population that contains 400,000 to 1,000,000 asbestos fibers per liter of water. Because the asbestos occurring naturally Is so wide spread on the East and West eoast and along the border with Canada, Billions of Americans receive dally and substantial exposures to asbestos froa birth froa these natural sources. The Increased activities In cities and the concentration of large nuabers of the population on a dally basis eauses even further Increases In exposures, some froa aanaade products such as elutehes or brakes of vehicles. Jt Is not uncoaaon to find airborne concentrations of asbestos in such communities at levels of about .002 flbers/cc of air, rising to occasional peaks of .02 flbers/cc or more. ~ . The background levels of natural occurring asbestos In air is so prevalent that the EPA took Into account the Influence for clearance of school buildings following ' an asbestos removal (14). It Is not uncoaaon to find the ambient airborne concentrations exceeding those Inside office or school buildings. The current-EPA criteria for clearance of a school building following an asbestos removal project 6 Is .02 fibers/cc by transmission electron microscopy for total fibers. At that level the EPA considers the building cleared for occupancy. Doll A Peto (25), Weill A Hughes (26), and Hughes A Weill (17) all have Bade contemporary predictions of the risk o environmental exposures at these levels. Doll and Peto predict one excess death from environmental exposure in a year in the United Kingdom. Sueh a low level of risk at the known environmental levels In the United Kingdom and the United States would account for the fact that mllllonsof people ao exposed do not demonstrate asbestosrelated diseases; suggesting a lower no-effect level. 3. VOLUME OP ASBESTOS USED IN SHIPYARDS: It is important to make a contrast between the discussion of environmental exposures-and the amount of asbestos used In a Hava2 Shipyard in the 2940's during the World War II years. The Plelscher- Drinker report on Naval shipyards published in 1946 shows that in those small industrial communities 100,000 to 200,000 pounds of asbestos products would be used each month in ship construction (II). The report made no mention of the volume of asbestos that needed to be removed prior to overhaul or renovation. The amount of material alone ' sets the conditions for high levels of exposure to workers handling the asbestos under these conditions. About 90S of the products used were' amosite blankets or pads, loose amoslte, magnesia block insulation, and asbestos cements. 7 4* All of these saterials were loose, easily broken or crumbled, and handled directly by workers. The potential for high level exposure, especially peaks, is apparent. Few effective control aeasures were in place at that tlae largely because the real risk from high level exposures over long periods of tlae were not realized because of the extreae latency period. 4. EXPOSURES OP THE CONSTRUCTION AND SHIPYARD TRADES: There are several studies that atteapted to define the occupational exposures to workers in the construction and shipyard trades in the 1960's. They constitute a cross section of the Aaerlcan experience at controlling high level occupational exposures where they were occurring In Industry. In 1970, Mangold, Beckett, and Bessaer (3,4) published a report on exposures to asbestos at Puget Sound Naval Shipyard showing that 21k of asbestos workers showed pulaonary abnormalities. They concluded that the TLV of 5 MPPCF was too high, that peaks were important, and that changes of work practices were required. The publication contains the levels of exposures recorded for the workers activities. In 1968, W.C. Cooper and L. Baltzer (19} published a similar study of construction workers in the San Francisco Bay area. About 25k of the construction workers handling asbestos products and receiving high level exposures showed x-ray changes of the lungs. They concluded that the TLV was too.high and needed to be reduced. The types of products and 8 the level* of occupation*] exposure for the construction workers was recorded. In 1971, Gaensler (20) published a study of exposures and medical findings in a private shipyard on the East coast. He concluded that exposures were too high and that the TLV should be reduced. A comparison of the asbestos exposures by job are contained in the report. These three studies show that the use of large volumes of asbestos with corresponding high levels of exposure were coasonplace among those required to handle or remove It. Such substantial levels of exposure are those that account for the asbestos-related diseases following long latency periods. The concentrations are many orders of magnitude*" above background levels, or environmental exposures. ' 5. CURRENT ALLOWABLE LEVELS OP EXPOSURE: The American Conference of Governmental Industrial Hygienists (ACGXH) adopted a Threshold Limit Value (TLV) for asbestos in 1946 of S millions of particles per cubic foot of air sampled for an 8 hour time-weighted average workday (TWA). It remained in effect until 1969, when It was reduced to 2 KPPCF or 12 flbers/cc. Currently, separate TLV's are published for each type of asbestos used commercially; A. Chrysotile: 2 fibers/cc, 6 hr TWA B. Amoslte: .5 flbers/cc, 8 hr TWA C. Crocldollte: .2 fibers/cc, 8 hr TWA D. Other: 2 fibers/cc, 8 hr TWA 9 A The current OSKA Federal standard for occupational exposure to asbestos is .2 flbers/cc for ail forms of asbestos used commercially. It makes no distinction between the types of asbestos. The regulation specifies the use of a speciml technique of air sampling and laboratory analysis by phase contrast microscopy at 400 X magnification (11). The SPA now regulates school clearance following an asbestos removal project to .01 flbers/cc as determined by transmission electron microscopy, a preelse method that measures all asbestos fibers present (14). It Is apparent that the AC'CXH recommendations do not agree with the OSHA permissible exposure limit. The EPA clearance"level Is aimed at public policy for schools where asbestos Is managed, or removed. 6. CONTINUING EVALUATIONS: Following control programs In the 1960's and 1970'a and more recently those mandated by Federal or State regulations, the overall occupational exposure levels to workers has dropped markedly. Investigator!have now turned to other sources of asbestos used In Industry to determine the contribution to the overall exposure. If any. In the 1960's the major goal was to reduce the - 10 high level exposure* occurring from highly friable asbestos materials used in large volume in construction and in shipyards. The small volume products and those that were encapsulated were not considered because of the small contribution to the overall exposure pattern (3,4). And, because tests revealed that'the low emissions were obscured by the high background levels from other highly friable products (3,4,19,20). Most of the data In the earlier reports evaluate processes which include the Influence of all sources of asbestos that may be present. Zt Is difficult to differentiate the contributions of the various types of asbestos produets which were being used at the same time, or in near proximity to each other. 7. U.S. NAVY GASKET REPORT: Zn 1978, the D.S. Department of the Mavy (21), as part of a continuing evaluation program, set about evaluating the asbestos exposures to workers from the storage, handling, and processing gaskets of all kinds in Xaval shipyards. The evaluation is important because there are only a few such publications that identify and estimate the occupational exposure to gasket materials in shipyards, the report concludes that even the simplest of general housekeeping controls or work practices are sufficient to maintain occupational exposures at-acceptable levels. In fact,- ' most of the exposures were found to be less than .1 fiber/cc 11 for an 6 hour TWA, a level at which aedleal exaainations are not required according to the current Federal standard for asbestos. The 1978 U.S. Navy report did achieve the intended purpose to deteralne the exposure to any and all asbestos In the breathing zone of workers but does not deteralne the actual contribution froa the gaskets alone. The breathing zone air saaples were collected for various foras of gasket processing in soae work areas under uncontrolled conditions and In the presence of contaalnatlon froa other asbestos products. The results are actually the contribution froa the gaskets, background levels, and contaalnatlon froa other asbestos products. They do not reflect the actual contribution froa the gaskets. Because the airborne - concentrations were extremely low, often .01 flbers/ee or less, the potential for contaalnatlon Is certain and cause a major contribution to the reported values for gasket processing. Many of the reported values reflect the actual exposure tine; not an 8 hour time-weighted average. The 8 hour TWA aeasureaent or calculation Is necessary to be able to coapare the values to the current Federal standard. Short tern peak exposures aeasured In this way will nearly always be greater than the hr TWA, often by several orders of aagnltude. While the 1978 U.S. Navy report achieved the Intent there are several objections in the use of the 12 i* data to reflect the actual contribution froa gaskets alone. They are; A. Short tera peak exposures are reported that cannot be directly coapared to the hour TWA of the Federal standards. Br Ko atteapt was aade to eontrol or factor the contributions of contamination froa the results. The contaalnatlon levels aay even have exceeded the actual contribution froa the gaskets processed. C. The data was Intended to deteralne the overall peak exposures froa unit operations that included all asbestos contributions. - The saall contributions froa gaskets are confounded or obscured by high background contaalnatlon levels where the gaskets were processed, contaainated clothing, and ataospheric pollution. 8. VERIFICATION OF THE 1978 U.S. NAVY STUDY: Because of the objections offered above, the U.S. Navy report could not be used with accuracy.to reflect the actual contribution of gaskets alone. In 1982, the Garlock, Inc. comaissioned C.A. Mangold (22) to repeat the U.S. Navy investigation on gaskets as nearly as possible and to take into account the effects of contaalnatlon in order to sake estimates of the actual contribution of gaskets to the occupational exposure of a worker handling or 13 processing then. In addition, the data was to reflect the 8 hour tine-weighted average work day for direct comparison to the existing Federal standards for asbestos. Samples of the ambient air were collected in various cities to show the apparent level of natural and aanaade < asbegtos fiber pollution. The effects of contaminated clothing that, a worker may wear were evaluated to determine the contributions. All sources of contribution were considered to control or factor those background levels that were not part of the contributions from the processing of the gaskets. After the background levels were measured or controlled, the data showed that hardpressed or encapsulated Garlock, Inc. gasket products released Insignificant levels Into the breathing zone of workers processing gaskets in the same manner as conducted in Naval shipyards. The actual contribution for the processing of gaskets averaged .02 flbers/cc for sum hour TKA when the effects of contamination from other sources or asbestos products were controlled. The peak background levels of ambient air in industrial areas, or in cities on warm summer days may reach these levels. This verification of the U.S. Navy report revealed that when the contamination was factored or controlled the values for the actual contribution from gaskets were about 50k of those'reported' by the U.S. Navy. The study conducted by Mangold (23) more appropriately 14 4* reflects the actual contribution fron handling or processing encapsulated gasket for an 8 hour tine-weighted average work day. The overall average of .02 flbers/ee is l/10th of the current Federal standard for occupational exposure to asbestos fibers in air. 9. THE DILEMMA^ The verification of the 1978 0.9. Havy report shows that hardpressed or encapsulated gaskets actually contribute negligible amounts of asbestos when handled or processed as in Industry or in shipyard. Negligible exposures present a negligible risk. The risk is in the sane aagnltude-as sone envlronaental exposures to the population at large. However, additional aeasurenents under highly controlled conditions- are needed because; A. Some workaen describe specific aethods of handling, processing or removing gaskets fron Machinery or piping that were not evaluated in the 1978 U.S. Kavy report or the subsequent verification. Sons are not standard operating practices expected of workaen experienced in the handling, processing or renoval of encapsulated gaskets froa aachlnery or piping. B. The 1978 U.S. Kavy report and the 1982 verification contains the effects of levels of contaalnatlon that are in the sane range as the expected* actual contribution of airborne asbestos fibers froa the gasket alone. Therefore, IS the results will be shewed upward by that contamination contribution. Better definition is needed where the effects of other asbestos products do not Interfere with the tests. C. Ambient concentrations of chrysotlle asbestos fibers that occur naturally froa soil and water, and froa aanaade products add some contribution to the aeasuraaents of the ealsslon froa gaskets. The contributions can be substantial and in the ease range as the expected actual ealsslon froa the gaskets being handled, processed or reaoved. D. New analytical aethods that were not available or practical for the U.S. Navy report In 1978 or the verification in 1982, are now readily available and within economic practically. These aethods ean provide a aore precise examination of the actual 'release of fibers froa encapsulated gaskets. ' E. The new analytical aethods have a such .lower limit of detection that those used la the 1978 and 1982 reports. The aethods now available can not only deteraine the total number of fibers present, but deteraine the types of fibers they are. This is valuable because the chrymotll* asbestos is used in encapsulated gaskets. P. The new analytical aethods can make a direct comparison to the older Phase Contrast Microscopy (PCM) method specified in the Federal standard through the use of Scanning Transmission Electron Microscopy (STEM). It can verify the PCM aethod which is easily influenced by other non-asbestos fibers, if they are present. 16 C. A better definition of by-stander exposure was needed, that is, the levels of exposure of a worker 5 or 10 feet away froa another worker aaking, installing, or removing encapsulated gaskets. 10. EXPERIMENTAL DESIGN: . Although the 1978 U.S. Navy report and the 1982 verification show that only negligible aaounts of asbestos fibers are released from the handling or processing of gaskets, additional aeasureaents are needed to utilise the new analytical methods, to.better control the effects of ambient or manmade contamination, and to determine the actual contributions froa the gaskets handled in the ways described by some workmen. And, the by-stander exposures froa those selected processes. A clean room condition was needed for the testing in order to accurately measure the low level release of ehrysotlle asbestos fibers froa the encapeulated gasket materials processed or removed from flanges. Since the emissions were expeeted to be near the limit of detection of phase contrast microscopy methods used, special precautions were taken to control potential contamination. _, A new metal building was leased in Eent, Washington 17 where electron microscopy samples showed that the amount of natural ambient asbestos was .002 flbers/ec or less for all sizes of fibers. The new building was selected to ensure that aceuaulatlon of dust, or previous asbestos Insulation contamination was not present. Inside the building, an enclosure of polyethylene plastic was constructed that measured 20 feet by 20 feet and 10 feet high, or 4000 eublc feet. This represents a saall compartment or rooa where such work say be done in Industry or aboard ship and that aay be occupied by a by stander. The celling and floor was covered with polyethylene plastic and all the edges were sealed. The only entry was a specially designed flap door that would reaaln sealed during testing. A clean work bench was placed in-the center of the enclosure "The gaskets were processed on the bench according to the descriptions given by soae workmen. Sample locations were assembled on the points of the compass at head height Inside the room. The sample stations were located 5 and 10 feet away from the work bench in the center of the room. The sample cassettes for analysis by phase contrast mlcroseopy and scanning electron microscopy were placed at the sample stations. Air was drawn through the special filters in the cassettes by electrically operated high volume air samplers. The volumes of air were measured by recording the flow rates'with'"a class A rotometer and recording the amount of time the samples were collected. Kine 18 J* PCM and 6 STEM samples were collected for each test. One PCM was worn by the operator at the work bench to record the breathing zone exposure. The other sample stations provided a preponderance of data and simulated by-stander exposures at 5 and 10 feet away from the gasket processing. Samples of gasket material containing chrysotile asbestos were obtained from the manufacturer for processing. And. piping and valves were obtained from a O.S. Xaval vessel, the DSN Gypsy (AXSD-1) which was scrapped In Portland, Oregon. She was built In 1944, served In the Pacific Theatre during World War II, and was decommissioned In the 1950's. Some of the flanges had never been opened since the vessel was built. All of the residual asbestos Insulation on the outside of the piping was removed to prevent contamination when the gaskets were removed from the flanges. Plastic Impregnated protective clothing (TYVEC) was worn by the operator to control the potential release of non-asbestos fibers from street clothing, and dust from shoes. \ The tests were conducted over an 6 hour time-weighted work day. This Is necessary to develop data that can be directly compared to the Federal standard for occupational exposure to asbestos. Zt Is Inappropriate to attempt to compare peak exposures to the Federal standard. Following the tests, the sample cassettes were removed and delivered to ESSTEK, a highly qualified asbestos 19 analytical laboratory capable of conducting phase contrast microscopy (PCM) according to Appendix A, of the Pederal asbestos.standard, and transalsslon electron aicroscopy (TEM). Special arrangeaents were Bade to directly coapare the results by PCM with that obtained by TEM. The PCM analysis is subject to Influence by non-asbestos fibers that aay be present. But, the TEM aethod Is highly specific, deternlnes all asbestos fibers present, Identifies the type of fiber present, and has a very low Halt of detection about .002 struetures/cc (approximately equal to flbers/cc). Arrangement were aade to have at least 78* of the PCM saaples blind counted. This Beans at least two qualified asbestos counters would sake a determination without knowing the result of the other. The results are then compared. This minimizes the potential for counting errors. The PCM and the TEM saaples collected at each sample location at the same time and filtering about the same volume of air, were compared as duplicates. This provides two separate determinations with highly specific methods at the same location and gives a high degree of confidence that each determination Is comparative. The results and conclusions for the tests conducted are found In paragraphs 12 and 13. 20 11. REFERENCES: 1. A. Churg and M. Warnock, "Asbestos Fibers in the General Population", As. Rev. Reap. Disease, Vol 122 (1980) 2* W.T. Marr, "Asbestos Exposure During Naval Vessel Overhaul, As. Ind. Hyg. J. 25:264 (Kay-June 1964) 3. C.A. Mangold, R.R. Beckett, D.J. Bessser, "Asbestos Exposure and Pulsonary X-Ray Changes to Pipe Coverers and Insulators at Puget Sound Naval Shipyard," PSNS, Dept, of Navy, Breserton, WA. (August 1968} . 4. C.A. Mangold, R.R. Beckett; D. J. Bessser, "Asbestos Exposure and Control-Puget Sound Naval Shipyard," U.S. Dept, of Navy, TMay 1970) 5. 2.J. Sellkoff, J. Churg, E.C. Hassons, "Asbestos Exposure and Neoplasia", JAMA 188:22 (1964) ' 6. I.J. Sellkoff, J. Churg, E.C. Hassons, "Relation Between Exposure to Asbestos and Mesotheliosa", N. Eng. J. Med. 272:560-565 (1965) 7. I.J. Sellkoff, M.D., "Disability Cospensation for Asbestos-Associated Disease in the United States", Env. Scl. Lab, Mt. Sinai Hospital, City'Oniv., N.Y. (Report to O.S. 21 A Dept of Labor - (June 1962) 8. J.E. Craighead, B.T. Mossaan, "The Pathogenesis of Asbestos-Associated Diseases", H. Eng. J. Med., 306 (June 17, 1982). 9. M.R. Becklake, "Exposure to Asbestos and Busan Disease", N. Eng. J. Med., 306, (June 17, 1962) 10. W.J. Nicholson, A. M. Banger, X.J. Selikoff, "Epidemiological Evidence on Asbestos", Proceedings of a' Workshop on Asbestos Definitions and Measureaent Methods. (July 1977} Gaithersburg, MD, U.S. Dept. Commerce Pub. # 506 (Nov 1978) ' 11. _Federal Asbestos Standard: 29 CFR 1910.1001 and 1926.56: Occupational Exposure to Asbestos, Treaollte, Anthophyllite, and Actlnolite, Final Rules, (June 20, 1966} 12. Dr. Andrew Churg, "Chrysotile,- Treaolite and Malignant Mesothelioma in Man", Chest 93(3}: 621:628 (1988) 13. A. Churg and L. De Paoli, "Clearance of Chrysotile Asbestos froa Human Lung", Experlaental Lung Research, 14(5): 567-574 (1988) 14. Environmental Protection Agency: 40 CFR, Part 763, 22 Asbestos-Containing Materials In Schools; Final Rule and Notice, (Oct 30, 1987) 15. R. Doll and J. Feto, "Asbestos; Effects on Health of Exposure to Asbestos", London, Her Majesty's Stationary OfficeT (1986) 16. R. Weill and J. Bughes, "Asbestos as a Public Health Risk: Disease and Polley", Ann Rev Pub Hlth, 7, (1986) 17. J. Bughes and H. Weill, " Asbestos ExposureQuantitative Assessment of Risk", As Rev Resp Dls (1986) 18. W.E. Fleischer, F.J. Vlles, R.L. Cade, and Phillip Drinker, "A Health Survey of Pipe Covering Operations In Constructing Naval Vessels", J. Znd. Hyg. A Tox. 28:9 (Jan 1946) 19. J.L. Baltzer and W. Clark Cooper,M.D.," The Work Environment of Insulating Workers, Aa. Ind. Byg. Assoc., 29:222 (May-Jun 1968) 20. R.L.B. Murphy, Jr.M.D., B. Ferris, W. Burgess, J. Worcester, E.A. Gaensler, M.D., "Effects of Low Concentrations of Asbestos: Clinical, Environmental, Radiological, and Epidemiologic Observations in Shipyard Pipe Coverers and Controls", N. Eng. J. Med., 23:285, 23 (December 2972) 21. L.R. Llukonen, K.R. Still, R.R. Beckett, "Asbestos Exposure from Casket Operations", O.S. Dept, of Navy, Bremerton, Washington ( Kay 1878) . 22. C.A. .Mangold, "The Actual Contribution of Oarlock Asbestos Casket Materials to the Occupational Exposure of Asbestos Workers", October 1982, Bellevue, Washington. 24 13 & 14 RESULTS AND CONCLUSIONS: In order to aerie asbestos containing gasket stock a sharp instrument like a scribe or awl can be used to scratch a pattern. This Is particularly useful when the gasket to be shaped is of an odd. size or pattern. Workmen describe using this technique In the field to scribe stock gasket aaterlals prior to cutting or punching. This aethod aay be used In preparation of preparing a gasket when new pre-cut gaskets, or the proper cutting tools are not available. New Garlock Inc. Style 900/7735 gasket stock containing about 70* chrysotlle asbestos was selected for marking of gaskets with a scribe. This style Is ordinarily used for flanges and aachlnery parts. ' The snail sheets of gasket stock were marked with the scribe at a rate of 2 eaeh hour over 8 hours, or 16 Barkings of gasket material for cutting. The scribing was all that was done to simulate the descriptions of workers who have handled asbestos gasket materials in the.course of their work, and to establish the 8 hour time-weighted average for eompa-ison to permissible exposure limit of .2 flbers/cc in the Federal standard. The conduct of scribing gasket stock material inside a clean room with a low background and low ambient levels in air allows the measurement of .these expected low emission rates and establishes the potential exposure to any by stander near the operator scribing gasket materials in this 25 way. The 8 sampling stations situated around the room provided sufficient data to establish those ranges of by stander exposure. - The attached data sheets show that; 1. The electron microscopy methods for total chrysotlle fibers In samples collected' at each of 8 sample stations averaged .002 structures/ec or less. The struetures/cc are approximately equal to fibers/cc. This method determined all of the chrysotlle present regardless of size. There Is no total fiber standard. 2. The electron microscopy analyses of the samples for all fibers greater than 5 micrometers In length and '.25 micrometers In diameter is a method of comparison to the phase contrast microscopy method specified in the Federal standard._Jn this way the phase contrast microscopy results can be verified. The results showed that no fibers of chrysotlle were found that were greater than 5 micrometers In length. 3. The phase contrast microscopy results for the 8 sample stations averaged .003 fibers/ec, for fibers greater than 5 micrometers In length. This would represent the exposure pattern of a by-stander In the room with the operator. The exposure pattern of the operator scribing gasket materials was .005 fibers/cc, >5 urn in length. The difference between these.results- and the electron- microscopy results is likely due to other non-asbestos fibers that must be counted according to the analytical 26 rules. All.of the results represent an 6 hour time-weighted average for direct comparison to the Federal standard of .2 fibers/cc, >5 us In length. . The exposure pattern Is a fraction of Federal standard as expected. The hard pressed, encapsulated gaskets releases Insignificant amounts of chrysotlle asbestos during scribing processes. The precise electron microscopy methods verified and corroborated the results that the exposures are negligible in terms of the current Federal standard. ^ ' 27 . I0.W LOCATION OF SAMPLE STATIONS IN THE ASBESTOS FIBER FREE ENCLOSURE - fA/TCtf * KkP I6hl 0 5 vu * SN w B5NC.H 5S, #5/ /ftS* Enclosure Height 10' 20' . * IOS. SIT IXV Seribing of Gasket Materials* TRANSMISSION ELECTRON MICROSCOPY AIR fAMPLE ANALYSIS RESULTS CLIENT: Carl A. Mangold, CIH PROJECT: Garlock-Research REPORT I: 11200 PAGE: 3 of 12 CLIENT SAMPLE 10 ESSTEX ID CONCENTRATION CHRYSOTILE ALL SIZES STRUCTURE SIZE CHRYSOTILE COUNTED LENGTH >5.0 ua STRUCTURES (S/cc) DIAMETER >.25 UB CONCENTRATION LENGTH >5.0 DIAMETER >.25 S/cc T5N-25 12049 T5E-26 812050 T5S-27 812051 T5V-28 812052 T10N-29 812053 T10E-30 812054 T10S-31 812-055 T10W-32 812058 LAB BLAi<K NSD BLD* NSD BLD 1 0.002 NSD BLD NSD BLD NSD BLD NSD BLD 1 0.002 NSD Jr .fl&i. NSD NSD N5D NSD NSD NSD NSD NSD 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 xa <000 Analytical Sensitivity 0.002 S/cc NSD - No Structures detected BLD - Belov Level of Detection S/ec - Structures per cc fibers per cc BLP A530t^5`C? *OoZ ^/ec_ Environmental Safety Systems, Inc. Cateway Corporate Park, Bldg. 5 12122 Caleway Drive Seattle, Washington MISS (206) 243-6573 AIR SAMPLE ANALYSIS REPORT CLIENTi CSrl Mangold, C.I.H, 3033 170th Place_SE Bellevue, WA 98008 ESQJBCTt Gaxlock Research - Set IV Scribing of Gasket Materials REPORT it 50-128130 REPORT DAZEi . 12-09-88 PACE 1 of 2 DATE RBCETVffii 12-02-88 PC it lire Given CLIENT SAMPLE ID ESS 2D SAMFUE SAMPLE DATS VCL (L) FIBER FXHZ) BLANC Off FIBERS SRSSO COCNT COCNT /100 PUDS PER CC * MAT P5N-25 P5E-26 P5S-27 PSW-28 P10N-29 P10E-30 P10S-31 P10W--32 P-BLK-4 128130 11-30-88 ' 128131 11-30-88 128132 11-30-88 126133 11-30-88 128134 11-30-88 128135 11-30-88 128136 11-30-88 128137 11-30-88 )128138 11-30-88 128139 11-30-88 5760 5760 5760 5760 5760 5520 5040 5760 1080 0 39.0 31.5 37.0 31.0 36.0 28.0 41.0 24.5 9.0 2.5 100 2.50 100 ' 2.50 0.003 0.002 H L 100 2.50 0.003 L 100 2.50 0.002 L 100 2.50 0.003 L 100 2.50 0.002 L 100 2.50 0.004 L 100 2.50 0.002 L 100 2.50 < 0.005 VL 100 N/A BLANK SAMPLE LOCATICKSt Sasple 1128130 was taken north Sft at statics. X- 603 Ssnple #128131 was taken east 5ft at aatple station. Sanple #128132 was taken south 5ft at sacple station. Sample #128133 was taken west 5ft at sasple station. Bulk Sampling Ait Monitoring * Analysis Asbestos Abatement Equipment A Supplies AIR SAMPLE ANALYSIS REPORT CLIENT: Carl A. Mangold, C.X.H. PROJECT: G&rlock Research - Set IV SAMPLE LOCATZCIS (continued) i REPORT It 50-128130 PACE 2 Of 2 Sample #128134 wes taken north 10ft at sample station. Sample #128135 Mas taken east 10ft at sample statim. Sasple #128135 i taken south 10ft at sample station. Sample #128137 mbs taken west 10ft at sample station. Sample #128138 was a personal sasple in breathing zone of operator. Sasple #128139 was submitted as a blank. The samples analyzed in this report were prodded by third parties not subject to control by Bavdrararerital Safety Systems. Inc. (ESS) or its affiliates. Consequently, the results presented represent microscopic examinations in ESS laboratory facilities and ESS makes no representation as to sample collection techniques or procedures. Analysis was perfoaied using phase contrast microscopy trader the guidelines of NEOSH method #7400-A. * A minimum of' ten fibers per 100 fields is needed for reliable quantification. Samples with less than 10 fiber* per 100 fields are reported as less than ) the quantification limit. ' . Amounts of ncn-fibrous material are determined using charts for estimating composition from the Journal of Sedimentary Petrology (v. 25. pp. 229-234, 1955). Amounts repcuteri reflect nan-fibrous material density on sample filter only. Legend: T * Trace (less than 1%), VL Very Lor (2-5%), L Low (5-15%), M Moderate (15-25%), 8 * High (25-40%), VH Very High (greater than 40%). 2 Microscope Field Area 0.00785 am _ Analyst(s) - FV Exposed Filter Area 385.0 am? Reviewed by: