Document XM7XjKX6OaZL6oO2GJaR2qVg

Exhibit E <?-/ *9 Discussion of the Technological Feasibility of Attaining a 0.5 Fiber/Cubic Centimeter Time-Weighted Average Airborne Concentration of Asbestos Fiber in the Workplace as Proposed by OSHA in the Federal Register of Thursday, October 9, 1975 by Johns-Manville Corporation April, 1976 DUP U52470 DU 061785 C- / INDEX Title Page Summary & Conclusions ----- -----------------i Johns-Manville's Involvement in the Asbestos Industry - - 4 Plant Data (Table A) - .5 Major Problem Areas - -- -- -- -- -- -- 7 Fiber Introduction -------------7 Bag Opening Stations Fiber Handling Product Finishing -- - -- -- -- -- -- -8 Machining Sanding Case History 1 - Asbestos Bag Opening Stations - - - - 10 Process Descriptions ---------- Asbestos-Cement Pipe ---------Case History 2 - Reduction of Asbestos Fiber Exposures in Asbestos Cement Pipe Plants Case History 3 - Waukegan Pipe Plant - - Asbestos-Containing Boards ------ - - - - 22 Asbestos-Cement Asbestos/Calcium-Silicate -' Case History 4 - Billerica Plant - - Roofing - -- -- -- -- - - - _ . _ _ . -27 _ - 29 Roofing Felts Coatings ft Sealants Sealing Components ----- --- _ - - - 32 Molded Packings Sheet Gaskets Mechanical Packings Case History 5 - Manville Textiles Plant Building Systems --------- . . ... .._ 38 41 Asbestos Cement Sheets ACE (Extruded) Panels Paper - -- -- -- -- -- -- _ 45 DUP 1152471 1< \ DU 061786 Figura No. 1 2 3 4 5 6 7 8 LIST OF FIGURES PROCESS DESCRIPTION FLOW CHARTS Oparation Asbastos Camant Plpa Aabastos ContainingBoards Roofing Roof Coatings and Saalants Saaling Componants Shaat GasJests Mschanical Packings (Taxtilas) Building Systams Asbastos Camant Shaat ACE (axtrudad) Panals Papar Paga 16 26 31 36 37 43 44 46 DUP 1152472 DU 061787 SUMMARY AND CONCLUSIONS Johns-Manvilla has for many years installed mechanical exhaust ventilation systems, modified process equipment, and introduced new work practices in its plants manufacturing asbestos-containing products in an effort to reduce the airborne concentrations of asbestos fiber and other materials to which its employees are exposed. These procedures have been continuously upgraded and improved as the "state of the art" of dust control advanced. Until December 1971, the Threshold Limit Value or exposure limit for asbestos dust was 5 million particles per cubic foot. Dust control mechanisms which were installed prior to December 1971 were not designed solely to achieve 5 mppcf, but were designed to attain the lowest possible airborne concentration of asbestos dust in the workplace - with the goal wherever feasible, of reducing exposures below 5 mppcf in our asbestos-using operations. We employed what we believed, at the time of installation, to be the best avail able technology. Surveys performed by our industrial hygiene laboratories using the impinger technique - revealed that by 1970, we were close to achieving our goal; approximately 90% of our monitored asbestos-using work stations were under the then existing TLV. This accomplishment required a concerted effort by plant personnel and by our General Plant Engineering and Environ mental Control Departments. In addition to the design and installation of the best available dust control equipment, these efforts included the development of improved processes and techniques and utilized the expenditure of about $12,000,000 during the period 1950 to 1970. Efforts to control airborne concentrations of asbestos fiber actually were instituted well before 1950. Installatidn of dust control equipment dates at least as far back as the mid 1930's. No records presently exist as to the specific airborne concentrations of asbestos fiber present or the total expenditure for dust control made during this period. In December 1971, OSHA promulgated its emergency standard for exposure to asbestos dust. This standard specified an 8-hour time-weighted average exposure limit of 5 fibers per cubic centimeter, as determined by the membrane filter/perscr.al air sampler technique. Johns-Manville, on the recommendation of the Bureau of Occupational Safety and Eealth, had initiated this type of monitoring technique in our plants during 1969. At the time the emergency standard went into effect, we had completed the monitoring of our asbestos-using work stations DUP 1152473 (1) DU 061788 & ,\ C with this naw fiber counting method. An analysis of our industrial hygiene data in aarly 1972 showad that only 60% of our work stations complied with tha than naw OSBA exposura limit; contrastad to ovar 90% complianca with tha pre vious TLV of 5 million particlas par cubic foot. Following tha promulgation of tha Dacaabar 1971 OSHA amargancy standard, Johns-Manville imaadiataly initiatad programs to comply. These programs tiara furthar intansifiad aftar pro mulgation of tha parmanant standard, with its raquiramant of an exposure limit of 2 f/cc by July 1, 1976. As in tha past, our programs wara not primarily daaignad to aehiova 5 f/cc or 2 f/cc, but rathar, wara targatad towards achieving tha lowast faasibla level, with tha minimum goal of all work stations baing balow 2 f/cc by July 1, 1976. Wa again employed what wa considarad to ba tha bast avallabla dust control tachnology and institutad work practicas and procass modi fications that wara davalopad for thosa situations whara wa beliavad availabla dust control tachnology would not ba adaquata. Thasa intansiva afforts wara guidad by our Environmental En gineering Department. Three case histories are included in this report detailing our afforts ovar tha years to reduce airborne concentrations of asbestos at three different manufacturing facilities. These histories define specific problem areas and possible steps that can ba taken to furthar reduce asbestos fiber concentra tions . By mid 1975, it appeared that our environmental control afforts which had required giving up tha manufacture of soma products and an expenditure of $8,500,000 from 1971-1975, would ba successful. Industrial hygiene surveys showad approx imately 90 cos^lianca with tha July 1, 1976 limit of 2 f/cc. Whan OSBA published its Aetober 1975 Notice of Proposed Rulemaking-Occupational Exposure to Asbestos - with a proposed 8-hour TWA axposura limit of 0.5 f/cc, wa examined our indus trial hygiene data to determine our compliance status. This examination indicated that as a result of our intansiva past endeavors, 45% of our monitored work stations wara already in complianca with tha proposed Permissible Exposure Limits. It must ba clearly understood that tha attainment of 45% of our monitored work stations balow tha proposed Permissible Exposure Limits of 0.5 f/cc in no way implies, let alone assumes that tha application of bast availabla tachnology can similarly raduca airborne concentrations of asbestos fibers at all of tha remaining work stations. To tha contrary, bast available technology has already bean applied to most of thasa work stations. It is fair to conclude that 45% of our monitored work stations do comply with the proposed permissible exposure limits 0UP 1152474 (2) DU 061789 '/^y only because best available technology was successful at these stations and was not successful to the same extent in other process steps in dux facilities where the same control efforts were made. A review of our industrial hygiene data for all of our asbestos industry segments indicates that, in general, the process steps with major problems, that is, process steps with TWA fiber counts above 0.5 f/cc, are concentrated in two areas: ' 1. Fiber introduction a. Bag opening, emptying and disposal b. Fiber handling 2. Finishing a. Machining b. Surface sanding These are not the only problem areas that will need study and development effort in order to reduce exposure levels. These two process steps are major operations, common to many asbestosproduct manufacturing facilities and will require the greatest attention from Johns-Manvilla. Our study of these major problem areas has convinced us that en tirely new processes, methods, and equipment must be developed by trial and error, with no guarantees that the proposed Per missible Exposure Limits can, in fact, be met. It is impossible to predict now the cost and implementation time for these develop ments. We don't know what will be needed to achieve compliance. CONCLUSIONS: 1. DESPITE THE MAXIMUM FEASIBLE EFFORTS OF MANY YEARS EMPLOYING BEST AVAILABLE TECHNOLOGY, jfE HAVE NOT BEEN SUCCESSFUL IN REDUCING EMPLOYEE EXPOSURES TO AIRBSME CONCENTRATIONS OF ASBESTOS TO BELOW 2 F/CC AT ALL WORK STATIONS. 2. BEST AVAILABLE TECHNOLOGY CAN NOT ACHIEVE COMPLIANCE WITH THE PROPOSED TWA EXPOSURE LIMIT OF 0.5 F/CC. EQUIPMENT, PROCESSES AND WORK PRACTICES, UNAVAILABLE UNDER EXISTING TECHNOLOGY, WILL HAVE TO BE DEVELOPED THROUGH THE TRIAL AND ERROR METHOD - WITH NO ASSURANCE OF SUCCESS. 3. BECAUSE OF MANY UNKNOWN FACTORS, IT IS IMPOSSIBLE NOW TO PREDICT THE COST AND TIME REQUIRED FOR THESE DEVELOPMENTS SUCCESSFUL OR OTHERWISE. DUP I 152475 (3) DU 061790 JOHMS-MAHVILLE'S INVOLVEMENT IN THE ASBESTOS INDUSTRY Johns-Manville is the largest manufacturer of asbestoscontaining products in the unitsd Statss. Zn 1974, we usad 197.000 tons of asbestos fibar in producing 620,000 tons of goods that sold for approximately $185,000,000. Canadian Johns-Manvilla Company, Ltd. (C-JM) is tha largast producar of asbastos fibar in tha Western world. It is estimated that in 1976 C-JM will nine and sail 720,000 tons of asbastos; 421.000 tons in tha United States, tha remainder internationally. Of tha amount sold in tha U.S., Johns-Manvilla itself will consume 146,000 tons, plus 44,000 tons from other asbastos sources. - Johns-Manvilla operates 20 plants manufacturing asbestoscontaining products in tha U.S., employing over 3800 people. Table A on page 5-6 sets forth specific details on these plants, including employment and financial data. Our product lines can be categorized into 6 major asbestos industry segments. 1. Pipe -Asbestos-cement pressure and sewer pipe, conduit indvents for the construction industry. 2. Boards - Plain and pigmented asbestos-cement boards for the electrical, laboratory furniture and construction industries. Asbestos reinforced calcium silicate boards for fire retardant partitions, oven construction and for the aluminum industry. 3. Roofing - Asphalt saturated asbestos roofing felts, roof coatings and cements, putties and sealants for residential, commercial and industrial building construction. 4. Sealing Components - Molded packings, sheet gaskets, and asbestos textile based mechanical packings for original equipment installation and maintenance of mechanical equipment. 5. Building Systems - Extruded asbestos-cement wall panels and shapes, formed flat asbestos-cement sheets and lamin ated A/C sheet panels for commercial and industrial building construction. 6. Paper - Commercial asbestos paper and high purity specialty asbestos paper for the electrical industry. Pipeline feltfor underground pipe protection. 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MAJOR PROBLEM AREAS As noted in the "Summary and Conclusions" section of this report, there are two process steps, common to most asbestos industry segments, where control of airborne fiber generation is of major concern, because past efforts have been unsuccessful in reducing eiqployee exposures consistently to less than 2 f/cc, to say nothing of reaching 0.5 f/cc as an 8-hour TWA. 1. fiber Introduction a) Bag opening, emptying and disposal, (common to all asbestos industry segments) Since 1954, we have designed and installed 18 different bag opening stations. None has been successful from the standpoint of maintaining exposure levels below 2 f/cc. Presently, the TWA airborne asbestos concentrations to which our enployees are exposed at our best bag opening station, range from 0.8 to 2.2 f/cc, with an average of 1.1 f/cc. Fiber counts for all bag opening stations range from 0.8 to 8.6 f/cc. In addition to our own development efforts, we have tested three commercially available automated bag opening systems. None were suitable because at frequent intervals during their operations, portions of the kraft or plastic bag would enter the raw material mix. Zn many of our asbestoscontaining products,particularly asbestos-cement products, these contaminants result in faulty units which must be rejected. In order briefly to illustrate the considerable investigation by Johns-Manville of possible alternatives, a history of our efforts to develop a bag opening system follows this section in the reports. It is titled: "CASE HISTORY 1 - ASBESTOS BAG OPENING STATIONS."' As a result of our investigation of possible alternatives, we believe that a fully automated bag opening system, which includes a provision for bag disposal to meet EPA standards, represents our best chance for complying with the proposed permissible limit of 0.5 f/cc. A workable system is unavail able under existing technology. It will be necessary for the asbestos industry, in conjunction with an equipment manufacturer,' to undertake a major program to develop a suitable system. b) Fiber Handling (common to many asbestos using operations) Presently, the TWA airborne asbestos concentrations to which our employees are exposed at various fiber handling opera DUP 1152479 (7) DU 061794 tions rang* from lass than 0.5 to 1.4 f/cc, with an avaraga of 1.0 f/cc. Development of an improved varsion of tha nagativa willow system praaantly usad in our pipa plants must ba undartaJean. If this davalopaant is succassful, complete systaas oust ba installad in plants prasantly utilizing diffarant procaduras, and tha improvements must ba incorporatad in tha pipa plant systaas. Operations in tha fibar handling "downstream" from tha nagativa willow systaa Bust ba carafully studiad and iaprovad aathods of dust control davalopad. Zf trial installation of a naw nagativa willow system and iaprovad "downstream" oparations provas than inadequate and unable to raduca. airborne concentrations of asbestos to within tha proposed Exposure Limits, than a wet feeding systaa must ba davalopad and utilized. This system would coaqpletely replace existing fibar handling equipment from after tha bag opening station to delivery into the forming machine. Johns-Manvill* presently is proposing a $545,000 project to develop and install such.a system on one machine at one of our asbestos-cement pipe plants. 2. Product Finishing (common to many asbestos industry segments) a) Sawing of asbestos-containing boards TWA airborne asbestos concentrations to which our employees are exposed at sawing oparations range from less than 0.5 to 4.5 f/cc, with an average of 1.5 f/cc. Saws usad in board trimming and fabricating oparations prasantly are equipped with mechanical exhaust ventilation for dust control. Tha first stap in an attempt to achieve compliance with tha proposed permissible Exposure Limit would be the design and trial oparation of refined dust control equipment and procedures. b) Machining of pipe Machining operations include: (i) End trimming and shaping of pipe. (ii) Cutting and forming of pipe couplings. TWA airborne asbestos concentrations to which employees are exposed in our pipe machining operations presently range from less than 0.5 to 4.5 f/cc, with an average of 1.5 /=c. Pip* machining is performed on specially designed equipment DUP 1152480 (3) DU 061795 C-! 6e with dust collection hoods at all points of dust generation. These hoods are part of elaborate mechanical ventilation systems that exhaust through fabric bag filters. Initial development efforts would concentrate on the trial install ation of redesigned ventilation equipment on various types of existing finishing equipment. If trial installations indicate that this procedure will not achieve compliance with the proposed permissible limits, then new, automated machinery with dust collection as an integral part, unavailable under existing technology, must be developed from the "ground 19." Initial development efforts would concentrate on an automated pipe lathe--a lathe used to machine pipe ends. If trials of the new lathe are successful, then development work must be expanded to automate the other types of finishing equipment used in an asbestos-cement pipe plant. c) Board and sheet surface sanding Even though our existing sanding lines are relatively new (installed during the last five years) and equipped with manufacturer supplied sophisticated dust control systems, soma operating steps are even difficult to maintain at/or below a TWA of 2 f/cc. Exposure levels range from less than O.S f/cc at the feed end to 3.S f/ce at inspection and take-off stations. The major source of airborne fiber is residual dust on the face of the sheet that is not removed by the existing surface cleaning equipment. Further reductions in the airborne concentration of asbestos fibers from this oper ation can only be achieved by a more effective cleaning procedure. Equipment to achieve this goal is unavailable under existing technology and would have to be developed through a trial and error process. DU 061796 DUP 1152481 (9) CASE HISTORY 1 ASBESTOS FIBER BAG OPENING STATIONS For approximately 25 yaara, numaroua attempts have been made to reduce the exposure to asbestos fiber of workers in Johns-Hanvilie plants who are required to open bags containing asbestos fiber. Up to this time, despite the efforts enumerated below, no mechanical bag opening machine or manual bag opening station, has been develope that consistently meets all of the following specifications: 1. Maintains asbestos fiber exposures below a TWA level of 2 fibers per cc. 2. Opens bags without contaminating the process with the bag material. 3. Provides means for removing the empty bag. 4. Does not interfere with the process. Part of the problem is due to the diversity of packaging mater ials , size of the package, and differences between the pressure packed and loose pack bags. The problem was much more acute before the Canadian asbestos fiber industry made a major improve ment in fiber packaging with the introduction in 1954 of the pressure packed kraft paper bag, replacing the loose packed jute bag. The jute bag leaked fiber and was difficult to handle during the bag opening process, ftie pressure packed paper bag was smaller, easier to handle, and unless accidentally broken, relatively dust free. Asbestos fiber today may be shipped in loose packed or pressure packed lined jute bags, pressure packed paper, or pressure packed reinforced plastic. Package sizes may vary from grade to grade of asbestos fiber and from manufacturer to manufacturer. JohnsManville, like many other users of asbestos fibers, purchases fiber from various suppliers, often located in different parts of the world. Therefore, it is difficult, if not impossible, to achieve standardization with respect to bag type or size. The following is a history, that is by no means complete, of efforts made to solve the bag opening problem. 1. In 1954, a carefully designed bag opening station with a fiber breaker was installed at our Jeffrey Mine to refeed off grade or damaged pressure packed paper bags. 2. In 1954, we installed in our Nashua, N.S. plant a ventilated bag opening station with a screw conveyor on the bottom to feed amosite. DUP 1 152482 DU 061797 C-/6\ 2. In 1954, large hoods for opening and asiding empty bags were installed in the Thermobestos insulation operations in our Manville, N.J., Waukegan, 111. and Long Beach, Calif, plants. 4. In 1957, at our Billerica, Mass, plant, a mechanical bag opener was installed to open and empty jute bags containing aaosite. 5. In several of our asbestos-cement pipe plants, starting in 1958, ventilated belt conveyors were installed for opening, batching, and feeding dry mixers in the raw siaterial prepara tion area. 6. In the late 1950's, ventilated bag opening stations were in stalled on belts feeding Moody openers. 7. In 1960, a ventilated hood with fiber breakers in the floor was installed for feeding the boot of an elevator in our Manville, N.J. asbestos-cement extrusion operation. 8. In 1966, in our shingle plant in Manville, considerable work was done to develop a prototype of a manual, ventilated, bag opening station. The effort was reasonably successful, but great difficulty has been experienced in using the prototype in other processing areas. 9. In 1969, a commercial mechanical bag opener, called a bag splitter, was tried out on a test basis but did not work. 10. In 1969, an attempt was made to design an improved ventilated bag opening station for the Thermobestos insulation operations in our Manville plant. It did not work. 11. in the textile plant at Manville, many months and over $10,000 was spent trying to permit the use of an enclosed glove box for opening asbestos fiber bags. Knives of various types, conveyors, and mechanical* lids were installed in the system in an atempta to solve operating problems. Efforts were finally abandoned as unsuccessful. 12. A mechanical bag opening station, using a horseshoe knife cutter, was designed and tested in 1970 in our Waukegan plant. After many months of effort and many thousands of dollars of expenditures, it was abandoned as unsuccessful. 13. For several years commencing in about 1970, our Jeffrey asbestos mine purchased and tried to solve the operating pro blems of mechanically opening pressure packed fiber bags with various types of knife arrangements. It is not successful. 14. Since 1973 , our Jeffrey Mine has worked almost constantly or. a second mechanical opening station using a guillotine type of principle to open pressure packed bags of fiber. To data, this effort is not successful. (11) DU 061798 DUP 1152483 15 . In 1975, an improved manual vantllatad bag opening station was installed in our Green Cove Springs, Fla. pipe plant. 16. In 1975, an improved manual bag opening station was installed in our Toronto, Canada pipe plant. Trouble was experienced in opening bags o blue and amosite fiber. This trouble was corrected, but the opened fiber cannot be carried away by the proosss elevators. This effort is continuing, but is not successful. 17. In 1976, our Jeffrey Mine purchased and installed an English bag opener that is reputed to work well with asbestos fiber. It is still too early to say whether this opener will be successful. 18. In 1976, our asbestos-cement Pipe Division started a new effort to develop a manual bag opening station in an effort to solve process and environmental problems. As stated previously, despite all of the efforts enumerated above, tie have not been able to develop or find a mechanical bag opening machine or manual bag opening station which will consistently meet the four specifications listed above. Some cannot meet any of these specifications. (12) DUP 1152484 DU 061799 <2 -/6 <-f PROCESS DESCRIPTIONS To provide a batter understanding of the fiber control problems associated with each asbestos industry segment (product line), brief descriptions of the processes used to manufacture our line of asbestos-containing products are set forth on the following pages. These descriptions include: A. Flow charts which delineate the major process steps which result in fiber generation and report the range of fiber counts from our latest industrial hygiene sur veys. B. Comments on the major areas where new processes, methods and equipment must be developed. ASBESTOS-CEMENT PIPE Basic Description Asbestos-cement pipe is presently manufactured at 6 separate Johns-Manville manufacturing facilities. It is a durable, inexpensive pipe material, used primarily in underground appli cations. It is resistant to erosion and corrosion from internal and external factors. Two of the major attributes of asbestos-cement pipe are ease of installation and the integrity of the pipe joint. The pipe is manufactured in sizes ranging from 4" to 32" in diameter. The two major uses for asbestos-cement pipe are in water supply systems and sewer service. Additional uses include air handling systems and vent lines. The raw materials used in the production of asbestos-cement pipe are asbestos fiber, Portland cement and silica sand. Process Description Bags of asbestos fiber are conveyed on pallets by fork trucks to the fiber bag opening station. At this location, the bags are manually opened, the fiber removed, and the bag disposed under a dust control hood. The fiber is mechanically conveyed to a totally enclosed willow for opening or fiberizing. It is then air conveyed under negative pressure to fiber storage bins. Dust in the conveying air is removed by fabric bag filters and re turned to the fiber feed system. From the fiber bins, the fiber is conveyed to dry mixers, where it is mixed with the other dry ingredients, Portland cement and sand. Points of potential dust emission have dust control hooding. After dry mixing, these blended raw materials are mechanically conveyed to a wet mixer and then into the pipe forming machine. The asbestos-cement slurry is picked up from a felt and deposited f 13 > DUP 1152485 DU 061800 Masai / U' on a rotating mandrel. Daposition on the mandrel is continued undar pressure until propar thickness has baan attainad. After preliminary sat tha pipa is strippad from eha aandral, air curad and staaa curad. Tha curad pipa sactiona ara oonvayad by fork truck to tha finishing oparations. Hara tha pipa is cut to langth and and machined for the coupling device. Other machining opara tions performed include the manufacture of finished couplings from pipa stock. Machining is dona by single or multiple point lathe type tools. Elaborate dust collection pick-up hoods ara provided at each point of dust generation. All finished pipa is visually inspected and all finished pressure pipe is hydrostatically tasted. After inspection and tasting tha pipe is stacked into unit loads for shipment and conveyed by fork truck to an outside storage yard to await final shipment. In addition to tha standard pipe and couplings, pipe plants will produce special pipa lengths and a variety of special fittings including teas, elbows and reducers. Ttim currant range of airborne concentrations of asbestos fibers to which our employees ara exposed, without ragard to tha use of respirators in each process step in our asbestoscement pipa manufacturing facilities, are sat forth in Figure 1. As discussed in tha "Major Problem Areas" section of this report, the two process steps that will require extensive improvement in order to achieve the proposed exposure limits are: 1. Fiber Introduction a. Bag opening, emptying and disposal b. Fiber handling 2. Machining of Pipe Presently, the TWA airborne asbestos fiber concentrations to which our employees are exposed at our bag opening stations range fromO.S to 3.5 f/cc, with an average of 1.6 f/cc. A history of our concerted efforts in the past to reduce airborne concentrations of asbestos at out bag opening stations is set forth in "CASE HISTORY 1-ASBESTOS BAG OPENING STATIONS," in the "Major Problem Areas" section of this report. f 14) DUP I 152486 DU 061801 C-lb6 The TWA airborne asbestos concentrations to which our em ployees are exposed at different fiber handling steps range from less than 0.5 f/cc to 1.4 f/cc with an average of 1.0 f/cc. TWA airborne concentrations of asbestos to which our employees axe exposed at pipe machining stations presently range frost less than 0.5 f/cc to 4.5 f/cc, with an average of 1.5 f/cc. A history of our concerted efforts in the past to reduce airborne concentrations of asbestos at the fiber handling steps and pipe machining steps in our pipe plants is set forth in "CASE HISTORY 2 - REDUCTION OF ASBESTOS FIBER EXPOSURES IN ASBESTOS-CEMENT PIPE PLANTS - FIBER INTRODUCTION AND PRODUCT FINISHING," at the end of this industry segment section. Following CASE HISTORY 2, is CASE HISTORY 3 - WAUKEGAN PIPE. CASE HISTORY 3 traces the history of the major efforts at our Waukegan, Illinois pipe plant in past years to reduce airborne concentrations of asbestos. This history is representative of similar efforts at our other 5 asbestos-cement pipe plants. Steps which can be taken to further reduce airborne con centrations of asbestos fibers in these process steps are set forth under the "Problem Areas" section of this report. (15) 0UP DU 061802 bn I ul u a cl z UJ UJ cc o o (fl g 111 u<i v9 Q-g *3 CQ 0 Z <3 oi ss Qa. <r o | _0UaJ ky 5 - r - ts h-H - \C -1 -PI cvj DUP 1 152488 ~r Ul cn N o DU 061803 PROCESS STEPS CASE HISTORY 2 REDUCTION OF ASBESTOS FIBER EXPOSURES IN ASBESTOS-CEMENT PIPE PLANTS FIBER INTRODUCTION AND PRODUCT FINISHING Over past years, Johns-Manville has made tremendous efforts to reduce asbestos fiber exposures in our manufacturing plants. These efforts included modification of processing equipment, improvement of asbestos fiber packaging and continual updating of dust collection facilities. The work done in improving asbestos fiber packaging is discussed in the case history on bag opening stations. The following discussion reviews the high lights of the modifications to process'equipment and improvements in dust collection facilities. Fiber Introduction Bag Opening Stations Bag opening stations still remain a problem. This was discussed in CASE HISTORY 1. Fiber Handling Asbestos processing equipment, after the bag opening station, has changed from a completely manual operation to automated systems. The original systems utilized positive pressure pneumatic conveying systems, feeding to live bottom fiber bins, from which the fiber was mechanically conveyed to the dry and wet mixing operations. The early dust collection facilities associated with fiber handling were wet collectors, that were not completely reliable. These were replaced with an intermittent type of fabric filter, whose draw back was the requirement that the unit- be shut down for cleaning. In the mid 1950's, we constructed two new asbestos-cement pipe plants. These plants were built with the following successful innovations which substantially reduced airborne concentrations of asbestos fibers: 1. Negative pressure asbestos fiber conveying systems in stead of the previous positive pressure. This process change resulted in a spectacular improvement in airborne fiber concentrations in this portion of the plant. 2. Continuous automatic fabric filters were installed instead of the intermittent type. This improved filter design eliminated the necessity for shutting down the collector for cleaning. 3. Automatic weighing and conveying of asbestos fiber from the live bottom bins to the dry mixers. M 7) DU 061804 OUP l152489 4. Mechanical equipment for ecrap grinding, replacing the previous manual operation. These automated systems incorporated dust control to reduce employee exposures. 5. Live bottom bins for the automatic weighing and intro duction of scrap into the process were installed. This new equipment eliminated the previous completely manual process. These process improvements were so effective in reducing employee exposures to asbestos fiber, that they were quickly incorporated into our. other existing pipe plants. Finishing Equipment All of our pipe plants, when originally built, were equipped with dust collection systems on the finishing equipment. Be ginning in the late 1930's and continuing to the present day, a constant effort has been made to reduce the emission of airborne concentrations of asbestos fibers from the finishing equipment, by the installation of more effective hoods and total rebuild of control systems, as our knowledge of dust control procedures advanced. Some of the specific improvements incorporated in our plants were: 1. Complete redesign of the Universal pipe lathes that are used to machine pipe ends. This redesign included im proved dust control. 2. Redesign and replacement of complete dust collection systems including improved hoods, new ductwork to accomodate greater air flows and improved fabric bag filters. 3. Continuing efforts to improve the hood design on all finishing equipment. 4. Installation of mechanical equipment to remove the chips generated by the pipe finishing process. 5. Installation of central vacuum cleaning systems to improve plant housekeeping. (18) DUP 1 152490 DU 061805 '0 CASE HISTORY 3 WAUKEGAN PIPE PLANT We have chosen to review our dust control efforts at this location because it is our oldest asbestos-cement pipe operation; it was started in 1929. When the Waukegan, Illinois pipe plant was built it was equipped with limited dust control facilities, mainly on the finishing equipment. Fiber handling was manual with shovels used to convey the fiber into weigh boxes where it was mixed with sand and cement. A limited number of evaluations of airborne asbestos dust concentrations were made by industrial hygienists from our insurance carriers in the period 1930 to 1950. Unfortunately, records of the survey results are no longer available. In the early 1950's, the first major changes in process and mechanical exhaust ventilation equipment were made. These included: 1. Automatic weighing and mixing of the fiber, cement and sand. 2. Positive pressure air conveying, systems for the dry raw materials. 3. Additional mechanical exhaust ventilation capacity on the fiber bag opening, fiber conveying and raw material mixing systems. During this same period modifications were made on the dust control systems on the finishing equipment to improve effectiveness. Dust counts taken for us during the mid-1950's by our insurance carrier showed that approximately 90% of our monitored work stations were under the ACGIH TLV of 5 mppcf. In the late 1950's and early 1960's, the second group of major process and dust control modifications were installed. The most significant modification was the conversion of the positive pressure fiber conveying system in the wet end to a negative pressure system. This virtually eliminated fiber leakage from the system to the workplace. In 1958, we established the basic industrial hygiene laboratory system we have in effect today, with laboratories then located at three points in the United States and one in Canada. Our hygienists performed surveys at this location to determine asbestos dust concentrations using the impinger technique. In 1962 our surveys showed the situation as follows: No. of Work Stations Monitored No. over TLV of 5 mppcf High Low ______ mppcf 69 3 9.3 0.4 (ig-i DU 061806 DUP 1152-491 In 1968, the last ysar in which our asbestos dust surveys were made by the impinger technique, the situation was even better. No. of Work Stations Monitored High Low No. over TLV of 5 mppcf mppcf S2 0 4.5 0.4 In 1969, Johns-Manvilla began using the membrane filter/ personal air sampler technique for evaluating employee exposure to asbestos dust. The initial survey at this location was done in April 1969. While the last series of iopinger surveys had shown cooplete control, that is, no counts over TLV, this new monitor ing procedure indicated a much different situation. No. of Work Stations Monitored No. over ACGIS Proposed High Low TLV of 5 f/cc_________ ______ mppcf 51 15 25.9 0.6 These survey results triggered a program to further reduce airborne concentrations of asbestos fibers. After the promulgation of the OSHA temporary and permanent standards for exposure to asbestos, our efforts were intensified to assure compliance with the 2 f/cc exposure limit effective July 1, 1976. Modifications and improvements accomplished during the period of 1971 to the present include: 1. Utilisation of better methods for shipping and handling of asbestos fiber. 2. Installation of additional mechanical exhaust ventilation at the points of dust generation. Our records show that during the period of 1930 to 1972 approx imately $1,500,000 was spent for asbestos dust control improve ments at our Waukegan, 111. pipe plant. To these capital costs must be added $500,000 in engineering and plant development expense for a total of $2,000,000. This figure does not include added maintenance and operating costs estimated at $50,000 to $100,000 per year. Despite these efforts, only 38% of the stations monitored in our latest survey were below the proposed TLV of 0.5 f/cc. The present situation is: No. of Work Fiber Levels Stations Monitored Less than 0.5 0.S-2.0 2.0-5.0 Greater than * 73 28 38 4 2 In two critical areas - fiber introduction and product finishing (20) DUP 1 152492 DU 061807 Mamma <2-/7 new techniques and methods must be developed to meet the pro posed Permissible Exposure Limit of 0.5 ibers/cc. These two critical problem areas were discussed in detail in the "Major Problem Areas" and "Process Description" (Asbestos-cement pipe) sections of this report. (21) DUp 1152493 DU 061808 ASBESTOS-CONTAINING BOARDS Basic Description Asbestos-Cement Board* - Asbestos-cement board is a durabla non combustible material usad in numerous applications including build ing construction# alactrical switch gaar and laboratory fumitura. Aabastoa-caaant boards usad in building construction ara produced as flat or corrugated sheets# normally 4 feat wida with langths up to 12 fast. Thay hava axcallant waatharing resistance and ara suitable for roofing and siding. Electrical equipment frequently contains a variety of asbestoscement boards fabricated to shape. It can be usad as a structural mounting panel for alactrical switch gaar components. Pigmented asbestos-cement boards are used extensively in the laboratory furniture industry as a durable, chemical resistant laboratory bench top.- The raw materials used in the production of asbestos-cement boards are asbestos fiber, Portland cement and silica sand. Asbestos/Calcium-Silicate Boards -Johns-Manvilie developed MARir s (asbestos/calcium-silicate boards) for use as a structural fire resistive material in shipboard partitions. It has seen extensive use internationally in this application. Because the board has structural integrity, as well as fire resistance and insulating properties, it is widely used as a panel material in oven con struction. Heat treated MARINXTE is used throughout the aluminum industry. Raw materials used in the manufacture of asbestos/calciumsilicate boards are asbestos fiber, lime, natural diatomaceous earth and clay. Process Description Asbestos-Cement Boards Bags of asbestos fiber are conveyed on pallets by fork trucks to the fiber bag opening station. At this location the bags are manually opened, the fiber is removed and bags disposed under a dust control hood. The fiber is mechanically conveyed to a willow for opening or fiberizing and then to dry mixers, where it is mixed with the other dry ingredients, Portland cement and sand. After dry mixing, the materials are conveyed to a wet mixer. f 22) DUP 1152494 DU 061809 c- / The asbestos-cement sand slurry is gravity dumped into a hydraulic press, where it is pressed to the specified thickness and density. The formed sheet is stripped from the press and stacked on racks for air curing. After air curing, the sheets are conveyed by fork truck to autoclaves for steam curing. After steam curing, the sheets are conveyed by fork truck to the finishing department to be trimmed to size and for surface sanding to the required thickness and finish. The fin ishing department also will cut to order special sheet sizes and shapes. As discussed under the "Major Problem Areas" section of this report, the two process steps where it has been difficult to control airborne concentrations of asbestos fiber are: 1. Fiber introduction a. Bag opening, emptying and disposal b. Fiber Handling 2. Product finishing a. Saw fabricating b. Surface sanding Presently, the TWA airborne concentrations of asbestos to which our employees are exposed in tha fiber introduction steps r&nce from less than O.S to 3.5 f/cc, with an average of 1.3 f/cc. In order to further reduce asbestos exposures at these operations, two improvements are necessary. la. Installation of an automated bag opening system. er lb. Installation of a "negative willow system" and revised dust control procedures at other steps in fiber introduction, or Installation of the yet to be developed wet feed system. Exposures in the product finishing operation range from less than 0.5 f/cc to 3.8 f/cc, with an average of 1.5 f/cc. Possible reductions in airborne concentrations of asbestos fibers will require two modifications: 2a. Install, after development, improved mechanical exhaust ventilation systems on the fabricating saws. 2b. Implementation of new, improved procedures for cleaning the surface of sanded sheets. (23) DUP 1152495 DU 061810 That* proposed improvements and modifications are discussed in detail in the "Major Problem Areas" section o this report. Asbestos/Calcium-Silicate Boards Bags of asbestos fiber are conveyed on pallets by fork trucks to the fiber introduction station. Bags are mechanically elevated to a mezzanine where the bags are manually opened, the fiber is removed and bags disposed under a dust control hood. The fiber is air conveyed through a fiber opening system, and then into a vet mixer. The other raw materials are introduced at this lo cation. From the wet mixer, the slurry is conveyed to a gel tank where the initial chemical reaction takes place. From the gel tank, the slurry is conveyed to the press where the product is pressed to the specified thickness and density. The sheets are stripped from the press, placed in racks and conveyed by fork truck to the autoclaves for steam curing. From the autoclaves, the sheets are transported by fork truck to the racking and unracking station. Here the sheets are placed in special racks for transport through the drying ovens. After drying, they are unracked and transported to a temporary storage area. From tem porary storage, the sheets are taken to the sanding line where they are top and bottom sanded to thickness and the edges are trimmed to size. After sanding, the sheets are conveyed through a brush roll section for surface cleaning, through the turnover inspection station and to the sanding line take-off station. They are then transported to the finished goods storage area where they remain until prepared for shipment. The current range of airborne concentrations of asbestos fibers to which our employees are exposed, without regard to the use of respirators, in each process step in our asbestos-containing board manufacturing facilities (including asbestos-cement boards and MARINITI), are set forth in Figure 2. The major process steps where it has been difficult to control airborne concentrations of asbestos fiber are similar to the asbestos-cement board operation. 1. Fiber introduction a. Bag opening b. Fiber handling The TWA airborne concentrations of asbestos to which our employees are exposed in fiber introduction range from less than Q.5 f/cc to 8.0 f/cc with an average of 1.3 f/cc. 2. Product finishing a. Surface sanding Exposures at these operations range from lass than 0.3 f/cc (24) DU 061811 DUP U52496 C- / 76 to 3.2 f/cc,with an average of 1.2 f/cc. In order to further reduce airborne concentrations of asbestos in these process steps, improvements similar to those described for our asbestos-cement board operation must be made. Immediately following this process description is CASE HISTORY 4 Billerica Plant, which reviews the dust control efforts at this plant, and demonstrates the difficulty of controlling asbestos fiber emissions generated by the finishing of low density asbestoscontaining board products. (25) DUP 1152497 DU 061812 nn c OJ LU <r D o LL ----- -- ----- hm tfi i H----H -is -n -<n -cj PR O C E i STE.PS DUP 1152498 "l T i i---------1--------r~--"i--------- 1--------- r 0 oBf-isin^ocM -- a C i niw*u r- aa i Mi *3e-iMw\_i wm -A-i t .j DU 061813 <2 -/ 7<> CASE HISTORY 4 BILLERICA PLANT We have chosen to review our dust control afforts at this location in ordar to demonstrate tha difficulty of controlling asbastos fibar amissions ganaratad by tha finishing of low density asbestos-containing sheet products. Billerica was acquired in 1936 and production of MARINITE was begun in 1939. MARINITE is a calcium silicate, asbastos re inforced sheet formed from natural diatomaceous earth, lime and asbastos fiber. The ingredients are introduced directly into a wet mixer, pumped to gel tanks, conveyed to a press and pressed to shape. After pressing, the sheet is autoclaved, oven dried and fxnished to the correct size by a sanding operation. One of the major uses of MARINITE is in fire-safe wall partitions, primarily in marine construction. It is also used as a structural insulating panel in oven construction and a heat treated form is used extensively in the aluminum industry. The MARINITE production facilities, as originally installed, included dust control systems in the raw material preparation and finishing operations. Surveys performed for us by our insurance carrier during the period 1940 to 1943 indicated satis factory airborne dust levels as determined by the criteria of the period. During the period 1949 tc 1966, plant capacity was gradually increased and dust control systems were modified and enlarged to keep pace with this capacity increase. In 1958, Johns-Manville organized its own industrial hygiene facilities. Our hygienists performed a dust level survey using the impinger technique at this location in 1962. Results of this survey were as follows: No. of Work Stations Monitored No. over TLV (5 mppcf) High Low mppcf 15 5 41.0 0.6 During the period 1962 to 1968, numerous improvements were made in the plant. The most significant change was the replace ment of the individual finishing stations with a single pass finishing line. Simultaneously, adoption of a precision forming technique eliminated the need for saw trimming. An industrial hygiene survey performed in 1968 showed marked reduction in airborne asbestos dust levels. (27) DUP HS2199 DU 061814 Ho. of Work Station! Monitored Ho. ovr TLV (5 nppef) IS 1 High Low mppcf 6.3 0.3 Panda expended during the period 1950 to 1968 at our Billerica plant to achieve these asbestos concentrations in the workplace totalled $133/000. The first survey utilizing the membrane filter/personal air sampler technique was performed at Billerica in June, 1969. Results were as.follows: Ho. of Work Stations Monitored Ho. over TLV (5f/cc) High Low f/cc 18 11 50 0.4 Here again, is the situation where exposure levels were below the TLV by one measurement system, and suddenly many work stations were above limits by a new measurement technique. numerous modifications were made in this plant from 1969 to the present, with the goal of reducing exposures below 2 f/cc. These modifications included total replacement of the sanding line and its dust control system. Improvements were made in fiber introduction. A total of approximately $550,000 was approved in capital funds to undertake these dust control im provements, plus $125,000 for engineering and design. The latest industrial hygiene survey was performed at this plant in Hovember 1975. The data are: Ho. of Work Fiber Levels Stations Monitored Less than 0.5 0.5-2.0 2.0-5.0 Greater than 5. 22 6 11 4 1 Only 27% of our monitored stations are at or below the pro posed exposure limit of 0.5 f/cc, despite past efforts. The problem areas are similar to those in our other asbestos using operations - fiber introduction and product finishing. Possible steps for isqprovements were discussed in the "Major Problem Areas" and "Process Description (Asbestos-Con taining Boards) sections of this report. (23) DU 061815 MlaHfilies'' iniiiIBiiHiiltitTf-HpiMStBlI' ROOFING Basic Description tooting Falts - Roofing felts are asphalt saturated asbestos paper. This product is used extensively in "built-up" roofing systems for commercial and industrial buildings. The asbestos fibers impart dimensional stability and rot proofing to the felt. In addition to providing dimensional stability, the fibers permit slight movement of the felt to accommodate expansion/contraction movements of the building structure without cracking of the felt. Roof Coatings -Roof coatings are manufactured from cut-back asphalt, inert fillers such as limestone, and 5-10% asbestos fiber. These coatings are used extensively in built-up roofing systems and foundation water-proofing. The asbestos again imparts dimensional stability, while permitting slight expansion and contraction of the coating without cracking. Sealants - Sealants are manufactured from a variety of base material's such as castor oil, soybean oil and various resins reinforced with asbestos fiber. These products are used extensively for caulking in building construction and for general purpose sealing compounds in industry. Again the asbestos fiber imparts dimensional stability while still allowing a certain degree of flexibility. The current range of airborne concentrations of asbestos fibers to which our employees are exposed, without regard to the use of respirators, in each process step in our roofing man ufacturing facilities (only including roof coatings and sealants) are set forth in Figure 3. Process Description Roofing Felts - The airborne asbestos problems associated with the manufacture of asbestos roofing felts are discussed under the asbestos paper process description section of this report. Roof Coatings -Raw Material Introduction Bags of asbestos fiber on pallets are conveyed by fork trucks t: the fiber bag opening stations. At this location the bags are man ually opened, the fiber is removed and the bags disposed under a dust control hood. The fiber is conveyed from the bag opening station, to a fiber fluffer, and then into a mixer. DU 061816 (29) DUP H52501 The other raw materials are introduced at the mixer. From the mixer, the finished product is conveyed to the filling station, where pails and cans of various sizes are filled and capped. The only process step which generates significant concentra tions of airborne asbestos fiber is bag opening in the fiber introduction segment. Presently, the TWA airborne concentrations to which our employees are exposed at this operation range from 0.8 to 2.5 f/cc, with an average of 1.2 f/cc. In order to further reduce airborne concentrations of asbes tos at this process stepk the use of an automated bag opening system, as described under the "Major Problem Areas" -section of this report will be required. Sealants - The process for manufacturing sealants is very similar "to that of coatings, except that a different mixer is used, and after mixing, the material is conveyed to an extruder for final processing to size and shape. The extruder is followed by a packing station where the sealants are prepared for shipment. Again, the only process which generates significant concen trations of airborne asbestos fiber is bag opening in the fiber introduction segment. Exposure levels are similar to those at the roof coating operation. The steps which must be taken to further reduce airborne concentrations of asbestos are the same as described for roof coatings. (30) DUP M52502 DU 061817 FIGURE 3 PROCESS STEPS 2? <\l U. (A Q v3 1 U u 0 0 Sj.rvW"Jc 3JBV41 N l^N^Td V/V\J_ - 7Z7/J DU 061818 SEALING COMPONENTS Basic Description Molded Packings -Precision dynamic sealing elements ara oada in a wide range of compounds, aizas and eroaa aactiona. Thay ara uaad for sealing baaringa, preventing oil aaapaga and axcluding dirt in a largo variety of aachanical equipment. Moldod packings ara gonarally mada from aynthatic rubber, and ara roinforccd with canvas duck, asbostos taxtila, or asbastos-containing shaat gaakat. Sheet Gaskets - Shoots of varying compositions ara uaad to seal two flat aurfacas against leakage. Examplas of applications are pipe flangos, cylindor hoads, valva covars, and angina crankcasas. Shaat gaskats contain 70% to 30% chrysotile asbastos fiber, bonded with rubbar, or other compounds. Mechanical Packings (Asbostos Taxtila Based)- Mechanical packings consist of a wide range of materials designed to control laakaga between moving or stationary parts. Primary application is with pumps and valves. Thay ara in a great variety of styles, shapes and cross sections. These packings generally ara made from asbastos textiles im pregnated with rubbar or graphite, reinforced with wire, and sometimes encased in wire mesh. Process Description Moldod Packings - This fcrodutft is precision die molded, single or multi-cavity, in a hydraulic press. Asbastos textiles or asbestosrubber bonded shoot gaskats ara used as heal reinforcement. There is virtually no asbostos exposure resulting from this process, since the asbostos is supplied to the process in bound form. Sheet Gaskets - Bags of asbastos fiber ara transported on pallets to the bag opening station. Hera, bags are manually opened,the fiber removed,and bags disposed under a dust control hood. Fiber is mechanically conveyed to the fiberizing device, then air con veyed in a negative pressure system to the feed cyclone. From the cyclone, fiber is fed through a rotary air lock to the wet mixer, where it is combined with the other raw materials, mainly rubber and solvent. The conveying air is cleansed by a fabric bag filter (32) oup "S2S0`' DU 061819 C- /?y and the captured fiber is returned to the system. The blended raw materials,in paste form, are transported by box truck to the two roll sheeter. The sheeter rolls the paste into a sheet, which is stripped from the rolls and air cured. The current range of airborne concentrations to which our employees are exposed, without regard to the use of respirators, in each process step in our sheet gasket manufacturing facil ities are set forth in Figure 4. The process step that presently generates fiber levels above 0.5 f/cc is bag opening. Exposure levels presently vary from 0.8 to 3.5 f/cc. In order to reduce airborne concentrations of asbes tos at this process step, an automated bag opening system, as discussed in the "Major Problem Areas" section of this report, must be utilized. Mechanical Packings - Mechanical packings are produced in two forms: 1. Braided from asbestos yarns. 2. Folded or formed from asbestos cloth. Braided packings are square, round or oval in cross section. They are braided in solid form or around various core materials. After braiding, the product is impregnated with rubber, graphite, TFE, molydisulphide or petroleum wax. Lubricating surface coatings are frequently used. Folded packings generally are square in cross section. They are folded to shape and bonded in their folded form with a neo prene base cement. The current range of airborne concentrations of asbestos fibers to which our employees are exposed, without regard to the use of respirators, in each process step in our mechanical packings manufacturing facilities, are set forth in Figure 5. The process step with major asbestos exposure is braiding. Even though the asbestos yam and asbestos cloth has been treated with a latex emulsion.during its manufacture, fiber exposure levels at the braiders range from less than 0.5 to 1.6 f/cc, with, ar. average of 0.9 f/cc. Zt is our present belief that additional, presently unknown, changes in the yam and textile manufacturing process will be required to further reduce airborne concentrations of asbestos fiber when handling asbestos textiles and yarns. In order to fully comprehend the magnitude of the problem (33) DUP 1 152505 DU 061820 expressed above, it is essential that asbestos textile manuf acturing be fully described, including industry attempts at dust control at the various process steps. In 1973, two scient ists, Robert A. Curtis and Philip J. Bierbaum of the National Institute of Occupational Safety and Health made an in-depth study of the industry. Their report "Technological Feasibility of the 2 Fibers/cc Asbestos Standard in Asbestos Textile Fac ilities" includes an excellent description of the three basic manufacturing procedures. 1. Dry; or conventional 2. Damp; used by Johns-Manville 3. Wet (Liquid dispersion process) During their study, Curtis and Bierbaum visited five "model" plants offered by the industry for their inspection. They con cluded that only two plants; plant A (Johns-Manville using the damp process) and plant B (Using the wet process) had a possibil ity of achieving the 2 f/cc standard. They stated that both these plants had limited production facilities due to product restraints created by the new processes. Curtis and Bierbaum conducted an asbestos dust sampling sur vey at these two plants. Results are given in their report. Their data for Plant A (Johns-Manville) and our most recent survey data are shown in the Table below. Operation NIOSH Range Mean J-M Range Mean Carding Twisting Weaving Braiding 0.2-2.6 0.8 0.1-1.5. 0.5 0.1-0.7 0.6 0.0-0.7 . **.2 0.1-1.4 0.3-1.5 0.1-0.8 0.3-1.6 0.9 0.8 0.8 0.9 The only serious discrepancy in data occurs in the braiding operation. Numerous repeat samples recently taken have con vinced us that our data is correct. Many variables - such as product mix - influence airborne fiber levels, and their effect can be determined only over a period of time. To effectively supplement this portion of the report we enclose two items : 1. A copy of "Technological Feasibility of the 2 Fiber/cc Asbestos Standard in Asbestos Textile Facilities" by Robert A. Curtis and Philip J. Bierbaum of NIOSH. This report is enclosed because of its excellent des cription of the asbestos textile manufacturing process and its conclusion concerning control of airborne concentrations of asbestos fiber. DUP 1152506 f 341 DU 061821 C-Ub 2. CASE HISTORY 5 - which describes the control efforts at our Manville Textile operations. This report includes our conclusions on the feasibility of attaining a 0.5 f/cc Permissible Exposure Limit. (35) DUP 1152507 DU 061822 PROCE.S5 STEPS tfl Id oj CC 3 O IL SJ.NV"Id CAM. Nl 3*?NVd V/VNJ. - 3 j j DUP 1152508 DU 061823 37 : 101-112 ( 1975) . Rajhans, G.S., and Bragg, G.M.; A statistical analysis of asbestos fiber counting in the laboratory and industrial environment. Am. Ind. Hyg. Assoc. J. 37:909-915 (1975). DUP 1152509 44 DU 061824 ssmm y-ja--ritTT I TABLE 12: Sample Averages, Standard Deviations, Coefficient of Variation, Median, Low count and High Count For Samples given in Tables 2-11. Sample Mo. Average Std. Dev. Co.of var. Median Low Eig 1 .22 2 1.5 3 5.1 4 .13 5 1.8 6 1.0 7 4.8 8 .4 9 .3 10 .3 .09 1.5 1.6 .05 .9 .7 1.1 .09 .17 .13 .42 1.00 .31 .40 .50 .70 .23 .22 .55 .37 .19 1.1 4.7 .13 1.5 .7 4.8 .4 .2 .3 .09 .5 .5 6.1 2.5 8.0 .06 1-0 .24 4.4 0.4 2.6 2.1 6.7 .3 .6 .2 .7 .2 .6 C* DUP 1152510 DU 061825 References Asbestosis Research Council: Technical Note 1 -- The Measurement of Airoorne Asbestos Dust by the Meabrane Filter Method. Revised September, 1971. Beckett, S.T., and Attfield, M.D.: Inter-laboratory comparisons of the counting of asbestos fibres sampled on membrane filters. Ann. Occup. Hyg. 17:1-12 (1974). Convey, R.E., and Holland, W.D.: Statistical Evaluation of the Procedure for Counting Asbestos Fibers on Membrane Filters. Prepared for Asbestos Information Association/North American, 1973. Edvards, G.B., and Lynch, J.R.: The method used by the O.S. Public Health Service for enumeration of asbestos dust on meabrane filters. Ann. Occup. Hyg. 11:1-6 (1968). Harness, I.: Airborne asbestos dust evaluation. Ann. Occup. Hyg. 16:397-404 (1973). Joint AIHA-ACGIH Aerosol Hazards Evaluation Committee: Recommended procedures for sampling and counting asbestos filters. Am. Ind. Hyg. Assoc. J. 37:83-90 (1975). Joint ACGIB-AIHA Aerosol Hazards Evaluation Committee: Background documentation on evaluation of occupational exposure to airborne asbestos. Am. Ind. Hyg. Assoc. J. 35:91-103 (1973). Knight, G.: Overlap problems in counting fibers. Am. Ind. Hyg. Assoc. J. 36:113-114 (1975). Leidel, N.A.: Optimum Sampling Times for Airborne Asbestos Fibers. DSPBS, NIOSH TR-82, 1973. .Leidel, N.A., and Busch, K.A.1 Statistical methods for determination of noncompliance with occupational health standards. NIOSH:75-159 (1975). Leidel, N.A., Bayer, S.G., and Zumwalde, R.D.: USPHS/NIOSH Membrane Filter Method for Evaluating Airborne Asbestos Fibers. USPBS, NIOSH TR-84, 1973. Leidel, N.A., Busch, K.A., and Crouse, W.E.: Exposure measurement action level and occupational environmental variability. NIOSH.-78-131 (1975). Lynch, J.R., Kronoveter, K.H., and Leidel, N.A.: Validity of the Poisson Distribution in Dust Counting. NIOSH unpublished inhouse report TR-83. Ortiz, L.W., Ettinger, H.J., and Fairchild, C.I.: Calibration standards for counting asbestos. Am. Ind. Hyg. Assoc. J. 43 DUP 1152511 DU 061826 FLDS FIBERS F /H L 1I nw >^ c? o vi X 9 0<1 * i 'N n in xK "1 V> O >9 9t *\ + . + ^ *-s >C ,n c c>. vCg5(%0 rHr* ^091* m <ai. "h *t*i * (% oh- j K fLD S FIBERS r/M L TLOS FIBER S F /H L II I FLOS FIBERS P /H L FLDS FIBC IIS F /H L TWAF/MI, O .s- Dup 11525\2 DU 061827 T a b le 11. Sanple 10 FLD3 FIBERS F /H l FLOS FIB E R S F /H L FLOS FIBERS F/H L FLOS FIBERS F /H l FLOS F IB E R S F /M I. TWAF/IV. 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