Document wqX7NLaY57KG1GXd4exmGaOpV

LIST OF TABLES Number 2.1 Approximate Chemical Formula of the Asbestoses 5 _2.2 Chemical Composition of Common Fibrous Silicate Minerals 6 2.3 Chemical Composition of Asbestoses from Different Geographic 8 Locations [ 2.4 Physical, Chemical, and Mineralogical Properties of Varieties 9 of Asbestos [ 2.5 Chrysotile Grades by the Quebec Standard Test 2.6 Modifications in Grading American Mined Asbestos [ 3.1 Captive Fiber Sources for the Major American Asbestos Product Manufacturing Firms 13 15 22 [ 3.2 Twenty of the Largest U.S. Asbestos Product Manufacturers 23 3.3 Asbestos-Based Activity of Some }mjor Asbestos-Manufacturing 24 [ Companies 3.4 Industry Specialization and Primary Product Class 25 Specialization for Asbestos Product Producing Establishments: 1972 3.5 Asbestos Products Manufacture: Distribution of Plant Sizes 27 { 3.6 Asbestos Products Manufacturing: Total Employment as a 27 Function of Size of Facilities l 3.7 Asbestos Products }mnufacturing: Total Value of Shipments 28 as a Function of Size of Facilities l 4.1 Mine Production of Asbestos 31 4.2 U.S. Export of Asbestos (Unmanufactured) for 1965- 1975 32 [ 4.3a U.S. Export --By Country -- of Asbestos (Unmanufactured) 33 in 1975 I 4.3b U.S. Export-- By Country -- of Asbestos (Unmanufactured) from January, 1976, to June, 1976 34 f_ 4.4 U.S. Exports --By Country -- of Asbestos Manufactured Products in 1975 35 ( v FMSI 04826 -------------------. ASBESTOS INFORMATION ASSOCIATION NORTH AMERICA 1835 K Street, N.W., Washington, D.C. 20006 (202) 223-4885 27 April 1977 Memorandum For: R. Iwarsson, Abex Corporation W. Jones,. Safeguard Automotive Corp. J. Marsh, Raybestos-Manhattan, Inc. J. Riopelle, Bendix Corporation W~ Sleeth, Royal Industries E. Zacharias, Molded Materials Company Subject: EPA Contracted Study with Syracuse University Research Co.t::p -- Friction Materials In May of 1975 the Environmental Protection Agency contracted with Syracuse University Research Corp. for an Industrial Chemical Market Input/Output Profile in connection with studies of its Office of Toxic Substances. The contract (initially listed in the amount of $99,700) has been discontinued because of lack of funds, we have learned. However, on the subject of asbestos in the study, the general sections, and a section on friction materials were completed and submitted to EPA in draft form. This material is forwarded as a matter of interest. Please be advised that the paper is in draft form and has not been formally released by EPA. Therefore, it should not be quoted. The work by Syracuse University Research Corp. appears to be of high quality. Your comments will be appreciated. ereness . Executive Director cc: Standards & Technical Committee (Rhodes, Weaver,Weber, Fenner) Mr. Drislane, FMSI RHM:v Enclosures ------------- FMSI 04827 l r [ I I I I l r l [ r I l_ (_ I. l List of Tables (Cont'd) Number 4.5 4.6a 4.6b 4.7 4.8 4.9 4.10 4.11 4.12 4.13 4.14 5.1 6.1 6.2 6.3 6.4a 6.4b 6.5 6.6 U.S. Imports of Asbestos (Unmanufactured) for 1965 - 1975 U.S. Imports --By Country -- of Unmanufactured Asbestos in 1975 U.S. Imports -- By Country -- of Unmanufactured Asbestos, January to June, 1976 U.S. Imports for Consumption of Asbestos U.S. Imports --By Country -- of Unmanufactured Asbestos Products in 1975 Asbestos Supply-Demand Relationships, 1965-75 (Thousand short tons) Asbestos Distribution by End Use, Grade, and Type, 1974 (Short tons) Buyers of Asbestos and Asbestos Ore Time-Price Relationship for Asbestos Recent Prices of Various Asbestoses Projections and Forecasts for U.S. Asbestos Demand by End Use, 1973 and 2000 (Thousand short tons) American Asbestos Mines and Hills Value of Shipments of Asbestos Friction Materials U.S. Manufacturers of Asbestos-Bearing Friction Materials Binders and Property Modifiers in Automotive Brake Linings Average Brake Lining Composition Brake Lining Compositions from Patent Literature Summary of Published Data - Asbestos Emissions -from Brake Lining Use Estimated Asbestos Emissions by Jacko and DuCharme (1973) from Vehicles 40 42 43 44 45 46 46 47 49 50 51 55 60 62 76 78 79 82 90 vi FMSI 04828 ----~--- List of Tables (Cont'd) Number 6.7 6.8 6.9 Estimated Asbestos Emissions from Vehicles Using Rohl et al. (1976) Figures for Asbestos Content of Wear Debris ---- Asbestos Concentration During Automobile and Truck Brake Service Asbestos-Free Composition of a Disc Brake Pad 92 94 97 L ------- vii FMSI 04829 LIST OF FIGURES Number 2.1 Schematic Diagram of the Structure of a Chrysotile Fibre Formed of Several Scrolls of Individual Crystallites 3 2.2 Schematic Diagram of the Crystal Structure of an Amphibole Fiber, Indicating the Unit Cell Based on x7si8o22 (OH) 2 4 3.1 Asbestos Industry Structures 19 3.2 Asbestos Products Industry 20 4.1 Asbestos - Salient Statistics 30 4.2 U.S. Asbestos Demand, and Projected Trends to 2000 r 5.1 Possible Areas of Asbestos Deposits 48 53 5.2 Asbestos Mines in the United States 54 5.3 Quebec Production Trends, From Analysis of 1951 - 1970 Data 57 6.1 Geographical Dispersion of U.S. Friction Materials Plants 66 6.2 Dry-Mixed Brake Lining Manufacturing Operations 69 : I -- 6.3 Wet-Mixed Molded Brake Lining Manufacturing Operations l 6.4 Molded Clutch Facings Manufacturing Operations 71 72 6.5 Woven Clutch Facings Manufacturing Operations 74 viii FMSI 04830 DRAFT ~. TR 77-515 CHEMICAL MARKET INPUT/OUTPUT ANALYSIS OF ASBESTOS TO ASSESS SOURCES OF ENVIRONMENTAL CONTAMINATION. William M. Meylan Philip H. Howard Sheldon S. Lande I Center for Chemical Hazard Assessment Syracuse Research Corporation Merrill Lane Syracuse, New York 13210 Contract No. 68-01-3224 - Task III SRC No. Ll273-08 March 1977 Project Officer - Robert J. Carton Prepared for: Office of Toxic Substances U.S. Environmental Protection Agency Washington, D.C. 20460 FMSI 04831 NOTICE This document is a preliminary draft. It has not been formally released by EPA and should not at this stage be construed to represent Agency policy. It is being circulated for comment on its technical accuracy and policy implications. ' II I '-- L ii L FMSI 04832 TABLE OF CONTENTS l 1.0 INTRODUCTION [ 2.0 DESCRIPTION OF ASBESTOS 2.1 Composition and Properties of Asbestos 2.2 Asbestos Grading 2.3 Major Uses of the Asbestoses 1 2 2 11 12 2.3.1 Chrysotile 2.3.2 Crocidolite 2.3.3 Amosite 2.3.4 Tremolite and Actinolite 2.3.5 Anthophyllite L 3.0 DESCRIPTION OF THE ASBESTOS INDUSTRY 12 17 17 18 18 19 [ 3.1 Industry Structure 3.2 3.3 Types of Plan Numerical and tPserce~tage Distribution of Plants~ Employees, 19 24 26 l and Production 4. 0 MARKET INPUT/OUTPUT DATA 29 [- 4.1 Mine Production 4.2 Exports 4.3 Imports r 4.4 Supply-Demand-Use 4.5 Asbestos Fiber Prices 4.6 Future Outlook L 5. 0 MINING AND MILLING 5.1 U.S. Mines and Hills [ 5.1.1 Ore Characteristics 29 32 40 41 41 48 52 52 56 L 6.0 FRICTION MATERIALS 6.1 Statistics 59 59 [ 6.1.1 6.1.2 6.1. 3 [ 6.1.4 Use Quantity and Shipment Values Industrial Firms Plants Future Projections for Asbestos (Clifton, 1975) 59 61 65 67 [ iii FMSI 04833 Table of Contents (Cont'd) 6.2 -Manufacturing Process Technology 68 6.2.1 Molded Products 68 6.2.1.1 Dry-Mix Process 6.2.1.2 Wet-Mi)C Process 68 68 6.2.2 Woven Products 70 6.3 Composition of Friction Materials 73 6.3.1 Binders 6.3.2 Property Modifiers 75 75 6.3.2.1 Non-Abrasive Modifiers 6.3.2.2 Abrasive Modifiers 75 77 6.3.3 Composition 6.3.4 Summary 6.4 Asbestos Emissions from Brake Lining Use 78 78 80 6.4.1 Published Literature 81 6.4.1.1 Discrepancies in Asbestos Content of 81 Emissions or Debris 6.4.1.2 Collection Methodologies and Particle Size 85 i Distribution l~ 6.4.1.3 Analysis Techniques 6.4.1.4 Other Considerations 86 88 6.4.2 Emission Quantities 6.4.3 Human Exposure to Asbestos Emissions During Brake Lining Maintenance and Repair 89 91 L 6.5 Alternatives to Asbestos as a Friction Material 94 r l 6.5.1 The Role of Asbestos in Friction Linings 6.5.2 Alternatives in Brake Linings 94 95 6.5.3 Alternatives in Disc Brake Pads 96 6.5.4 Alternatives in Clutches 97 6.6 Summary and Conclusions for Asbestos Friction Applications 98 l_ REFERENCES 101 r L iv l FMSI 04834 List of Tables (Cont'd) Number 6.7 6.8 6.9 Estimated Asbestos Emissions from Vehicles Using Rohl et al. (1976) Figures for Asbestos Content of Wear Debris ---- Asbestos Concentration During Automobile and Truck Brake Service Asbestos-Free Composition of a Disc Brake Pad 92 94 97 : !._ r L ._ l r l r vii L. fN\S\ 04835 LIST OF FIGURES Number 2.1 Schematic Diagram of the Structure of a Chrysotile Fibre Formed of Several Scrolls of Individual Crystallites 3 2.2 Schematic Diagram of the Crystal Structure of an Amphibole 4 Fiber, Indicating the Unit Cell Based on x7si8o22 (OH) 2 3.1 Asbestos Industry Structures 19 3.2 Asbestos Products Industry 20 4.1 Asbestos - Salient Statistics 30 4.2 U.S. Asbestos Demand, and Projected Trends to 2000 48 .. 5.1 Possible Areas of Asbestos Deposits 5.2 Asbestos Mines in the United States 53 54 5.3 Quebec Production Trends, From Analysis of 1951 - 1970 Data 57 r 6.1 Geographical Dispersion of U.S. Friction ~aterials Plants 66 I 'L. 6.2 Dry-Mixed Brake Lining Manufacturing Operations 69 r I t- 6.3 Wet-Mixed Molded Brake Lining Manufacturing Operations 71 l 6.4 Molded Clutch Facings Manufacturing Operations 72 6.5 Woven Clutch Facings Manufacturing Operations 74 viii FMS\ 04836 1.0 INTRODUCTION This study on the commercial market and environmental sources of asbestos was undertaken for the following reasons: (a) to consolidate the large volume of published literature in an attempt to describe the asbestos industry and the uses of asbestos in terms of marketing data and statistics; and (b) to examine the potential for asbestos emissions from final end-use products. Asbestos emissions from mining and milling operations and from industrial factories have been examined in reasonable detail by previous EPA reports . However, no comprehensive attempt bas been made to examine the sources and quantities of asbestos which may be released to the environment from asbestos-containing products. Unfortunately, because of limited funds, this report considers only the [ asbestos emissions from friction materials such as brake linings and clutches. [ [ L [ l [ r ( l1 FMSI 04837 l l 2.0 DESCRIPTION OF ASBESTOS r 2.1 Composition and Properties of Asbestos "Asbestos" is not the name of a distinct mineral species but is a r commerical term applied to fibrous varieties of several minerals differing widely in chemical composition, the fibers being diverse in length, strength, [ flexibility, and consequent usefulness (The Asbestos Factbook, 1970). The [ varieties of asbestos most used commercially are chrysotile, amosite, crocidolite, and anthophyllite. Chrysotile, which accounts for approximately 95% of [ all asbestos consumed commercially, is of the serpentine group of fibers, while the other varieties (crocidolite, amosite, anthophyllite, tremolite,' and actino- [ lite) are of the amphibole group of fibers. Among the amphibole asbestoses, [ amosite and crocidolite are the most important commercially; anthophyllite, tremolite, and actinolite account for only minor commercial consumption (Kover, [ 1976; Clifton, 1975). Sometimes the literature refers to the common asbestoses with jargon names: "white asbestos" for chrysotile and "blue asbestos" for r crocidolite (Berger and Oesper, 1963). While the asbestoses differ in chemical composition, they share L similar polymeric silicate structure. The fibrile-like structures of the [_ asbestoses result from linear chains of silicate tetrahedra. Chrysotile and amphibole asbestoses fundamentally differ by the number and shape of the sili- l cate units. These differences can be visually identified from Figures 2.1 and [ 2.2, which are structure schematics of chrysotile and amphibole, respectively. Chrysotile consists of Si 2o5 silicate units arranged in double layers and formed (_ into a laminar structure. The chrysotile Si2o5 layers are joined by brucite (magnesium hydroxide) layers. This double layered structure is contorted in l 2 (_ FMSI 04838 --------- r [ l [ r r [ [ [ II l Figure 2.1. Schematic Diagram of the Structure of a Chrysotile Fibre Formed of Several Scrolls of Individual Crystallites (Each scroll is formed from a closely connected double layer having magnesium l hydroxide units on its external face and silica units on its inner face. The details of a small section of the scroll show the structure of the double layer and of the unit cell based on [ Mg3(si20s) (OH) 4 .) (Kover, 1976) I [ 3 L FMSI 04839 r L .--- l [[ L Figure 2.2. Schematic Diagram of the Crystal Structure of an Amphibole Fiber, Indicating the Unit Cell Based on x7si8o22 (OH) 2 (The line A-A L represents the edge of the preferred cleavage plane along which the fibres will split to form even smaller fibres.) (Kover, 1976) [ [_ [ 4 l FMSI 04840 ,- tubes in which the brucite forms the outer fiber layer. The amphiboles contain silicate a~ Si4o11 double chains in a banded structure. The chains are united by intercalcated cations and form as solid fibers (Berger and Oesper~ 1963; Badolette, 1963; Kover, 1976). f Unlike the synthetic chemicals which usually exhibit unique chemical [ compositions, the asbestoses are composed of mixed inorganic oxides. The vari- ous asbestoses are characterized by ranges of these oxides rather than precise r molecular formulas. Table 2.1 below gives the approximate chemical formula for .each of the varieties of asbestos, while Table 2.2 lists the typical ranges of mixed oxide compositions for the asbestoses and a few related minerals. Table 2.1. Approximate Chemical Formula of the Asbestoses [ (The Asbestos Factbook, 1970) r Chrysotile 3MgO 2Si02 2H20 [ Crocidolite Na2o Fe2o3 3Fe0 8Sio2 H2o [ Am.osite Anthophyllite l.SMgO 5.5Fe0 8Si02 H20 7Mg0 8Si02 H2o Tremolite 2Ca0 SMgO 8Si02 H20 Actinolite 2Ca0 4Mg0 FeO 8Si02 H2o L Since asbestos is a metamorphic mineral, its composition reflects the composi- tion of the surrounding minerals and its formation conditions. Therefore, the oxide composition range differs for asbestoses of different geographical origin, as evident from Table 2.3. The asbestoses contain relatively few elements. In 5 FMSI 04841 - ,._.,...._ ~ ~ .....~~~~,......~~ ~ .......... ~~,........,~-, CTI , 3en: 0 ~ 00 ~ N Table 2. 2. Chemical Composition of Common Fibrous Silicate Minerals (Kover, 1976) Typical ranges, wt-% Chrysotile Crocidolite Amosite Anthophyllite Actinolite Tremolite Talc Hornblende Orthopyroxene sw2 38-44 49-53 49-53 56-58 51-56 55-60 60-63 39-54 44-60 MgO FeO Fe2o3 40-43 0-3 1-7 28-34 15-20 21-26 30-32 3-25 4-39 0-0.8 13-20 "34-44 3-12 5-15 0-4 . o. 6-2.5 0.2-23 3.5-48 0.5-4 17-20 ----- ----- 0-3 0-0.5 0-1.5 0-9 0-3 Alz03 . CaO KzO 0.3-0.9 0-0.2 ----- 0.5-1.5 1.5-3 0-2.5 0-2.5 4-15 0-8 0-1.0 0.3-2.7 ------------- 10-12 11-13 0-1.4 9-13 0.2-4.2 Trace 0-0.4 0-0.4 ----- 0-0.5 0-0.6 ----- 0-1.7 0-0.6 Na2o H2o Trace 4-8.5 Trace ------- 0. 5-1.5 0-1.5 ------- 0.5-4.3 0-0.9 13-14 2.5-4.5 2.5-4.5 1-6 1.5-2,5 0.5-2.5 0-0.3 0-2.6 0-0.8 r r [ I r [ [ r { l l [-[ l [' I [ addition to silicate and water, they generally contain the oxides of magnesium, calcium, i:on, and/or sodium. Aluminum and potassium oxides are sometimes present as trace "impurities." The "impurities" are defined as the oxides which are not accounted in the approximate chemical composition. They can either form part of the polymeric structure or occur as occlusions within the fibers (Berger and Oesper, 1963). Table 2.4 describes some of the properties important in the commercia~ uses of asbestos. The properties of asbestos that give it commercial value are its fibrous structure, the great strength of its fibers, and its resistance to high temperatures and to certain types of chemical attack. Chrysotile asbestos excels commercially due to its fineness of fiber, high flexibility, good heat resistance, general workability, and ample supply. The longer fibers can be spun easily into textile materials. However, chrysotile degrades faster than the amphiboles in water, acids, or alkalis. This results from the solubility and reactivity of the brucite. While amphiboles lose only ca. 9% of their weight in 4N HCl after eight hours at l00C, chrysotile looses all magnesium hydroxide (60% of its weight) after only one hour in 1 N HCl at 95C (Berger and Oesper, 1963). When chrysotile is extracted by the Soxhlet procedure for four hours with aqueous alkali (pH 10.33), it loses a high percentage of magnesium ion and yields magnesium silicate. Crocidolite, when treated by the same conditions, will leach only 4% silica and 6% sodium {Berger and Oesper, 1963). Because crocidolite and amosite fibers are highly acidresistant, they are particularly valuable for use in chemical plant applications. Anthophyllite and tremolite fibers are too brittle to be spun or used as fibrous reinforcements but, because of their resistance to attack by certain chemicals, are used for filtering purposes in chemical processing plants and in laboratories. 7 FMSI 04843 - - -... ,.....,, .......1"--11 ~ ~ ~ ~, ~~~~ ,...... ~ ~ ........., --. Table 2.3. Chemical Composition of Asbestoses from Different Geographic Locations (The Asbestos Factbook, 1970) (X) ., 3: ~ 0t t Variety end .Location FeO 5102 (Ferrous (Silica) Oxide) Fe 2o~ (Fetr c Oxide) 6MnO o(AAlu1m2 in3a) MgO (Magne~ia) CaO (Lime) (M4ng>~neee Oxide) (So"d"ioUlll Oxide) (PotaKs2s0iulll n o- (COlli ined Oxide) Water) H20+ (Colllbined Water) Chrysotile (Quebec) 40,2 1.0 0.5 2.9 39.9 1.1 0.1 0.1 0.1 0.8 13.4 Chrysotile (So. Rhodesia) 39.7 0.7 0.3 3.2 40.3 1.1 0.3 0.1 0.1 0.6 12.2 Chrysotile (Ural Mts,) 38.1 1.3 1.4 5.0 37.7 2.2 0.1 0.1 0.1 0,8 11.1 Crocidolite (Cape Province) 50.9 20.5 16,9 nil 1.1 1. 5 0.1 6.2 0.2 0.2 2.2 Crocidolite (Australia) 52.8 14.9 18.6 0.2 4.6 1,1 Tnce 6.0 0.1 0.2 2.6 CrocidolHe (Bolivia) 55,7 3.8 13.0 4.0 13.1 1.5 Trace 6.9 0.4 Trace 1.8 Aalosite (Transvaal) 49.4 40.6 0,1 nil 6.7 0.7 o. 7 0.1 0,2 0.1 1.9 Anthophyllite {Finland) 59.1 6,7 1.0 0.9 29.7 0.1 0.2 0,1 0,1 0,5 2.4 TreiDolite (Pakinan) 55.1 2.0 0.3 1.1 25,7 11.5 0.1 0.3 0,2 3.5 0.2 Actinolite (Cape Province) 53.8 25.3 2. 0 1.2 4.3 10.2 0.4 0.4 0,1 0.2 2.6 r Table 2.4. Physical, Chemical, and Mineralogical Properties of Varieties of Asbestos (Kover, 1976) Property Chemical formula Ouvsotite Mg3Si20 5 !0HI4 Crocidohte Amosite AnL~ophyli;te TremoUte Actinolite N"o!Fe3 Si8 0 22 (0HI2 (FeMg)7Si80 2 z(OHlz (feMg) 7Si80 2 2 \0Hlz Ca2 Mg3Si80 2 2!0Hl 2 (CaMgFelsSi80 2 2(0Hiz --pH t.2to 9.8 --- Neutral -- -- l -- --Re\istance to Poor Good Good Good ec.ids [ Ve"'"' Cca....S sliplibon Crooa fibef Cros f;be< Slip. INS fib~ uncri,led SlipO< mus. libi!r Slip or mauli~ and interl.i<::ing - [ -toColor G.....,, ,oy, Blue 'Gray. vel!,... !odrk v..llowis.h br.,..,n, guyi\h Gravwhite. greenilh, vellowi\h, .- Greenlsh white brown v.hire bluilll [ Texture Soft to~'"' Sort to hor\h Coarse but Harth Generally H>r\h aloo silky somewhat horsh, pliable some-limn [ toft luster Sil~v Silky 10 dull Vitreous. Vitrrous to S.lky Silky 1011\ewhlt pearty [ pearly Hardness1 :Z.Sta 4.0 4 5.5 to 6.0 S.Sto 6.0 5.5 6~ r flexibility Hog~\ Gcod Good POD< Poor Poor [ Spinnability v.., good F1ir Fair Poor Poo< Poor [ Tensile strength. lb. in.2 824,000 '" 876,000 mo. 16.000 to 90.000 4.000 and ll!"ts 1.000 to 8,000 1,000 ,~nc,J Ius l Fusion point,F 2,770 2,180 2,550 2,615 2,400 2,540 [ Specific heat, Btu/lb.F 0.266 0.201 0.193 0.210 0.212 0.217 [ ~orking Scale of Hardness: 1 - very easily scratched by fingernail, and has greasy feel to the hand; 2 - easily scratched by fingernail; 3 - scratch by brass pin or copper coin; 4 - easily scratched by knife; 5 - scratch with [ difficulty with knife; 6 - easily scratched by file; 7 - little touched by file, but will scratch window glass. All harder than 7 will scratch window glass. l9 FMSl 04845 ,. r [ ( I I I r [ [ [ [ [ [ [ Table 2. 4. Physical, Chemical, and Mineralogical Properties of Varieties of Asbestos (Cont'd) Property Chrysotile Electric charge Filtration properties Positive Slow Specific gravity Cleavage 2.4to 2.& 010 perfect Crocidolite Noeatiw Felt 3.2to 3.3 110pMKt Amosite Negative Anthophyllite Ntgoti,. Fat MNium 3.1 to 3.25 2.85 to 3.1 110perfect 110 perfoa Tramolite Negative .......... Actinolite N. . .1 M Mocllwft 2.8to 3.2 3.0to 12 110perfect t10!Mrlect Optical properties Biaxial positive, extinction parallel Refractive index 1.50 to 1.55 Resistance to destruction by heat Good, brittle at high lemperatures Temperatura at ignition loss,F 1,800 Magnetic content,% Crystal structure O.Oto 5.0 Fibrous and asbestiform Biaxial. ex.tinction inclined 1.7 pleochn>ic Poor, fuses 1,200 Biaxial positive, extinction parallel aioiapooiti.. llltinctiOft parallel 8i..ill ntgotiv-, ntinc:tion indinod Biaxial negative, extinction Inclined 1.6U 1.61:t Good. brittl at hi!#l t&f!IPI<ItUI'U 1,1100 to 1,800 Very good 1.600 1.61t 1.63t -kly pleochroic Fair togaed -- --1,800 3.01o 5.9 Fibrou 0 Prism1tic. lomollor to fibrous 0 Prism otic. lamellar to libr.,.,. 0 -- Long ond thin columnar to librous Long lnd thin calum"ar to fibroua Crystal 1ynem Monoclinic and orthorhombic Monoclinic Monoclinic Minoralogical structure In veins of serjlantlne, ate; Fibrous in iron stones lamellar, coarse to fine fibrous and asbestiform Mineral association In altered peridotite adjacent to nrpentine and limestone near contact with baslc Igneous rocks Iron rich silicious argillita in quartzoso schists In crystalline schists, etc. Orthorhombic lamellar. fibrous asbastiform Monoclinic Monocfinic --- .. - - Long. rnarnilltc and fibrous awegates .-- R-tu;ycld lonc.a prismatic c:rystlls end fibers --- In crystalline schists and gneisses In Mg limestones as alteration product of magnesian rocks, metamorphic and Igneous rocks In limestones and In cryotalline schistl 10 FMSI 04846 Since asbestos is often used in the manufacture of insulation for electrical equipment, its electrical conductance is an important property. Its conductance is related to the magnetite (Fe304) content. As the content of this impurity increases, the asbestos conductance also increases (Berger and Oesper, 1963). The thermal stability is limited by asbestos metamorphosis to other mineral forms. The fusion points listed in Table 2.4 are not melting points for the asbestoses, but correspond to the fusion temperature of the metamorphic products. Chrysotile, for example, is thermally transformed to the minerals olivine or enstatite at a rate dependent upon time and temperature. The trans- formation may be important to assess some environmental losses for certain uses, such as in brake linings (Berger and Oesper, 1963). 2.2 Asbestos Grading Asbestos is graded by fiber length. It is not commonly graded by mineralogical content or other properties. The Quebec Standard for chrysotile is the most important, because most asbestos consumed in the U.S. is graded by this system. The Quebec Standard measures the distribution of fibers after sieving a 16 ounce sample through a system constructed of four boxes: three screens and a "pan" for fines: Box Number Screen Opening Diameter of Wire 1 0 . 5 0 0 11 0 . 1 0 5 11 2 0.187" 0.063" (4 mesh) 3 0.053" 0.047" (10 mesh) Asbestos fibers are graded in nine groups: Groups No. 1 and 2 are hand-cobbled crudes and the remainder are milled fibers. Group No. 1 is basically 3/4" staple and longer fibers, which makes the best spinning grade. Group No. 2 includes 11 FMSI 04847 l [ r [ l [ r [ [ [ [ [ [ [ [ [ [ [ l spinning fibers of lower quality. The milled fibers are grouped according to the box distributions listed in Table 2.5 (Berger and Oesper, 1963; The Asbestos Factbook, 1970). Other grading systems are also used for chrysotile and the amphibole asbestoses. They also grade fibers by length. U.S. mined asbestos basically .follows the Quebec Standard. Table 2. 6 describes the modifications used for Arizona and California mined asbestos. 2.3 Major Uses of the Asbestoses .The following discussion. briefly describes the major uses for the asbestoses and the reasons why they are used. }~rket input/output data concerning the quantities consumed according to use and grade are given in Section 4.0. 2.3.1 Chrysotile Chrysotile dominates the asbestos consumed in total quantity, value, and number of products. It accounts for about 95% of all the asbestos commercially consumed. (a) Asbestos Textiles The long chrysotile fibers (Grades No. 1, 2, and 3) are predominantly used for textile manufacture. The textile products can eventually be marketed as textiles such as safety clothing, drapes and curtains, wicks, etc. or they can be further processed with resins and other additives in the manufacture of friction materials, gaskets, laminated plastics, etc. (Kover, 1976; Hendry, 1965; The Asbestos Factbook, 1970; Clifton, 1975). (b) Asbestos Cement Medium sized chrysotile fiber (Groups No. 4 to 7) dominate in production of asbestos cement products (pipe and sheet). Asbestos cement 12 FMSI 04848 r [ r ( r [ r [ r [ [ r[ I [ [ ( f. [ Table 2.5. Chrysotile Grades by the Quebec Standard Test (The Asbestos Factbook, 1970) Standard Grade Designation Group No. 1, Crude No. 1 Group No. 2, Crude No. 2 Group No. 2, Crude run-of-mine Group No. 2, Crudes sundry Groups No. 3 through No. 9 Fiber Description - consists basically of crude 3/4.. staple and longer - consists basically of crude 3/8.. staple up to 3/4" - consists basically of unsorted crudes - consists of crudes other than above specified - are "Milled Asbestos.. Group No. 3: Group No. 4: Group No. 5 Guaranteed Minimum Shipping Test (Distribution of 16 oz. of Fibers) Box 1 Box 2 Box 3 3F 10.5 3.9 1.3 3K 7.0 7.0 1.5 3R 4.0 7.0 4.0 3T 2.0 8.0 4.0 3Z 1.0 9.0 4.0 4A 0.0 8.0 6.0 4D 0.0 7.0 6.0 4H 0.0 5.0 8.0 4J 0.0 5.0 7.0 4K 0.0 4.0 9.0 4M 0.0 4.0 8.0 4R 0.0 3.0 9.0 4T 0.0 2.0 10.0 4Z 0.0 1.5 9.5 SD o.o 0.5 10.5 SK 0.0 0.0 12.0 SM 0.0 0.0 11.0 SR 0.0 0.0 10.0 5Z 0.0 0.0 8.6 13 Pan (fines) 0.3 0.5 1.0 2.0 2.0 2.0 3.0 3.0 4.0 3.0 4.0 4.0 4.0 5.0 5.0 4.0 5.0 6.0 7.4 FMSI 04849 l [ Table 2.5. Chrysotile Grades by the Queb'ec Standard Test (Cont'd) ( r Group No. 6 r Group No. 7 l r r Group No. 8 r Group No. 9 [ [ [- [ L l [ [ [ [_ Box 1 Box 2 Box 3 Pan (fines) 6D o.o 0.0 7.0 9.0 7D o.o 0.0 5.0 7F 0.0 0.0 4.0 7H o.o 0.0 3.0 7K o.o 0.0 2.0 7M 0.0 0.0 1.0 7R o.o 0.0 0.0 7T o.o o.o 0.0 7W 0.0 0.0 0.0 11.0 12.0 13.0 14.0 15.0 16.0 16.0 16.0 8S under 50 lbs/cubic foot loose measure 8T under 76 lbs/cubic foot loose measure 9T over 75 lbs/cubic foot loose measure 14 FMSI 04850 [ [ [ [ ( ( ( [ [ [ r [ I l ( I ( l Table 2.6. Modifications in Grading American Mined Asbestos (The Asbestos Factbook, 1970) ASBESTOS GRADES IN ARIZONA Source: Metate Asbestos Corporation, Globe, Arizona The same "Guarantl'Cd Minimum Shtpping Test~" arc used in Arizona as arc used in Canada, with the follmving c":eptions: 3Z !Soft Filter Grade I is held to -- 0 10 4 2 Special Sugar Grade LX222NAW is held to about Canadian Gr:1dc 3T - 2 8 4 2 All other Arizona Grades follow Canadian grading procedures but add the following designations: s H AW NAW - Soft -- Har>h -Add Wa;hed - Non-Add Washed ASBESTOS GRADES IN CALIFORNIA Source: Coalinga Asbestos Company, Inc., Coalinga, California The following short Chry~otilc asbc~tus fiber grades arc available from Johns-Manville Corporation's CC>alinga Mine at Coalinga. Califurnia. While the chcmilal ..:lUlljlO\ilion of Californian libcrs is very ('hrpotilc. they arc typil:ally lighter m ..:olor,lower insimliinl~asr to thai l:Onlcnt of Canadian and higher in ~urf;.h..'C arc-a. U/. TRA BI:STOS Red Braml: a hi~h surface area, high absorption, low tine~ !!cncral-rurro'" ,h<Ht fiber. ULTRABI:STOS Blue Brand a similar to Canadian Grade 7R. high This quality, low lines Grade is prepared seh~ rt tiber aecialty somewhat for usc in vinyl floor tile. Cualinga FloaW an apprn>.imatdy 95?e cbxylrtchm~ clloykN'hcuttrltelisbt.cr(Sheacvirnag11ac minus 2{0 mesh con!cnt of 23 for a description of this test.) C:naliiiJ:O Parcrh<'stm-/00: an extremely 'hurt litwr prepared fur usc in the papcnnaking indu.,try a' a pat~h .:untrul and pi~,:rm:nt rct.:ntinn aid. C:ualiiiJ:fl ,l.fhnltit"" a m~uium ah,urptinn shurt !ihcr fur a'phall t>:rving applkatums. 15 FMSI 04851 -~--------------------- l [ I [ [ [ r r [ ~[ I[ 1~ [ I [ (_ L [ ( I. ( products account for the major portion of the asbestos consumption, both in ~tonnage of fiber and market value. The properties which contribute to its commercial position include fiber length and tensile strength (Kover, 1976; Carton, 1974; Berger and Oesper, 1963; Clifton, 1976). (c) Asbestos Paper and Felt Properties for which chrysotile is used in this product segment include.its capacity for heat and electrical insulation, its chemical and thermal stab.ility, its strength and flexibility (Kover, 1915; Carton, 1974; Hendry, 1965). Chrysotile grades from 3 to 7 are predominantly used (Berger and Oesper, 1963; Clifton, 1975). (d) Composition Materials The composition materials include plastics, asbestos-vinyl and asbestos-asphalt products, coatings, and compounds. Chrysotile is added to these products generally as a filler and reinforcement medium (Modic and Barsness, 1965; Seymour, 1968; Grove and Rosato, 1967). The longer fibers (including Grades No. 1 and 2) are used in the production of high grade laminated plastics. The short fibers (Grades No. 4 and shorter) dominate in the manufacture of most other composition materials (Clifton, 1975; Berger and Oesper, 1963). Although the quantity of fibers used in these products is large (the second largest consumption of fibers), the low value of the short fibers results in a low commercial value for asbestos used in this market segment. (e) Friction Materials The properties for which asbestos is used in friction materials include its capacity for thermal stability, its ability to act as a reinforcing agent, as a filler, for the regulation or inhibition of resin flow, its lower 16 FMSl 04852 .( abrasion than other fillers of its price range, and its dispersion of metal chips and other particulates (Hendry, 1965}. While the fiber lengths of Grades [ No. 4 to 7 dominate the friction materials, some longer fibers are also used l (Clifton, 1975). (f) Packing and Gaskets [ Chrysotile use in packings and gaskets is accounted for by its strength, resiliency, durability, toughness, and thermal stability (Hendry, lf 1965; Kover, 1976). Fiber length predominantly ranges from Grades No. 4 to 7, 1. although some Grades 1 through 3 are also consumed (Clifton, 1975; Berger and jl Oesper, 1963; SRI, 1974). ll 2.3.2 Crocidolite ' Crocidolite fibers are shorter and more brittle than chrysotile but have a slightly higher tensile strength. Crocidolite is principally con- sumed for the manufacture of asbestos cement products (Kover, 1976; Clifton, 1976). While it can be spun into fibers, its spinnability is not equivalent to chrysotile. Longer crocidolite fibers are sometimes mixed with chrysotile for textile production (Berger and Oesper, 1963). It is used as replacement for chrysotile fibers in some laggings, insulations, filter media, and packings exposed to corrosive (acid or alkali) substances (Fisher, 1967; Hendry, 1965; Kover, 1976). Long crocidolite fibers are also consumed in asbestos boards and papers (Berger and Oesper, 1963). 2.3.3 Amosite Amosite has lower tensile strength than chrysotile or crocidolite by more than an order of magnitude. It is consumed mainly in asbestos cement products. Other major uses are in various thermal insulations, including pipe l II and boiler coverings, bulkhead linings in ships, and 85% magnesia insulation (Hendry, 1965; Kover, 1976). 17 FMSI 04853 [ r 2.3.4 Tremolite and Actinolite Both tremolite and actinolite are of low tensile strength and [are brittle. They have only minor commercial use. They are primarily consumed as cheap fillers and as filtering mediums. Tremolite is sometimes puri- [ fied by acid treatment for special filtering purposes (Kover, 1976; Hendry, 1965). [ 2.3.5 Anthophyllite Anthophyllite is also of minor commercial value. It is mainly [ used as a filler in rubber, plastics, adhesives, and asbestos cement products l (Kover, 1976; Hendry, 1965; Clifton, 1975). [ [ [ [- i l [ r 18 FMSI 04854 3.0 DESCRIPTION OF THE ASBESTOS INDUSTRY 3.1 Industry Structure Figure 3.1 below is a simple illustration showing the movement of asbestos within the asbestos industry. Mining - - -.. Hilling ---+Primary Industries Secondary -----9.-Consumer Industries Industries Lconsumer Industries Figure 3.1. Asbestos Industry Structure The following definitions have been adopted (Daly et al., 1976): Primary Industries: those industries that start the manufacturing process with raw asbestos fiber and modify the fiber to produce an intermediate product (to be further processed or fabricated) or a finished product. Secondary Industries: those industries that continue the manufacturing process with an intermediate asbestos product (one in which the fiber has previously been modified in a primary industry), and further process, modify, or fabricate it to produce either another intermediate product (to be further process-ed or fabricated) or a finished product. Consumer Industries: those industries that purchase a finished asbestoscontaining product (from a primary or secondary industry), and apply, install, erect, or consume the asbestos-containing product without further physical modification of the product. This classification is depicted in Figure 3.2, which categorizes the various end uses by products. 19 FMS\ 04855 ~ I jliiiiiMt~" ......-...---~~"-~ .~---..-....~;.,~'to!' "~~-~~ --~~~~ ........ ............. ........ -----""'"'-'" wo'"$'# ~ ?e t'''' "- i:wi-= ~ '@WTt ''Wf &"" -"~---'=""-"""'~-~--- .....,~-- ~ !;' :J N 0 "1'\ ~ 0 t "Q') Primary Industries FLOOR TILE GASKETS & PACKINGS FRICTION PRODUCTS PAINTS, COATINGS & SEALANTS ASBESTOSREINFORCED PLASTICS ASBESTOS CEMENT PIPE ASBESTOS TEXTILES ASBESTOS PAPER ASBESTOS CEMENT SHEET MISCELLANEOUS Secondary Industries OFFICE, HOME, COl IMERCIAL FLOORS VAL V, FLA..aE, JW. TANK S1:AUNO COMPONENTS CLUYCHITRANSM SION, DRAKE COiolPOHENlS INDUSTRIAL FRIC ION MATERIIILS AUYOIIIOTIVEITR CIC. DOOV COATINGS IIOOF COA TINCS r.ll rl\ TCHlNO COMPOUNQ$ ELECYRIC MOYOR :oMPONENTS MOLOEO PAOOUC COMPOUNDS FOR HIOti STRfNQTHIWEIOifT USES CHEMICAL PROCE .PIPtNG WillER SUPPLY Pll NO CONDUITS fOR EL CTRICAL WIRES PACKING COMPOI :NTS OASKETCOIIII'ON YS ROOFING MATER ILS COMMERCIAL/I~[) JSTRIAL DRYING FELTS HEAT/ffRE PROTI :fiVE CLOTHINO CLUTCH/TRANSM iSIDN COIIII'ONENTS ELECTRICAL WIR ANO ~IPE INSULATION THEATER CURTA IS AND FIREPROOF DRAPERIES OASIVN'OR DUCT ,FOR CORROSIVE COMPOUNDS FIREPROOF AlSO BENTPAPERS TABLE PADS AND tEAT PROTECYIVE lilATS HEAT/FIR PROTI :TtON COMPONENTS MOLYEN GLASS H .NOLING EQUIPMENT INSULATION PROI UCTS GASKET COIIIPOH ~TS UNOERLAVMENT 'DR SHEET FLOORING ELECTRIC WIRE I liULATIOH fiLTERS FOR BEV' iRAOES APPLIANCE INSUI TION ROOFING MATER LS HOODS. VENTS FO ~CORROSIVE CHEMICALS CHEioliCAL l ANKS AND VUSEL MANUFACTURING PORYABLE CONST UICTION tiUILOINQS ELECTRICAL SWI' :H&OAROS AND COMPONENTS RtSIDENTIAL BU .DING MATERIALS MOL lEN lolETAL I ONDLINCl EQUIPMENT INDUSTRIAL BUll liNG MIITERIALS fiRE PROYECTION INSULATIOH PRO IUCTS SMALL APPLIANC COMPONENTS ELECYRICAL 11101 lR COMPONtN T5 LABOflATOAY FU 'NHURE COOLING TOWR :ut.WONENTS WHOLESALERS - Consurr r Industries ARCDEFLEI ORS, ELECTRICAL RESISTANCE SUPPORTS, WATER SUPPLY ANI ,WAGE PIPING, DECORATIVE BUILDING PANELS, PLASTER AI STUCCO, MOLDED PLASTICS, ACOUSTICAL PRODUCTS, SAPHALTP~ NG, CAULKING, MOTOR ARMATURES, PAINTS, AMMUNITKl WADDING, WELDING-ROD COATINGS, DRIP CLOTHS, FIREDOORi IUTOMOTIVE BRAKES AND TRANSMISSIONS, HEATER ELl ENT SUPPORTS, OVEN AND STOVE INSULATION, SIDINGSHII LES, AUTOMOTIVE GASKETS, ELECTRIC MOTOR CASINGS,EI :TROLYTIC CELL DIAPHRAGMS, FLOOR TILES, SPACEVEHI E HEAT SHIELDS, CORROSIVERESISTANT PIPING AND DUCTS:,MARINE BULKHEADS, TANKS FOR CHEMICALS, FIRE HOSES :ARMENTS, GLOVES, FILTER MEDIA, AUTOMOTII UNDERCOATINGS, BOILER INSULATION, FURNITURE, PUMPAND1 ,VE SEALS, MOTION PICTURE SCREENS, ROOFING . PRODUCTS, LTEN-METAL CONVEYORS, RUGS, WALLBOARD, POWERCAB INSULATION, ELECTRICAL SWITCHES - -Figure 3.2. Asbestos Products Industry (Daly et al., 1976) The first industry segment to come into contact with the asbestos is, of course, the mining segment. As far as the United States is concerned, how- ever, this predominately occurs in Canada. From 1971 to 1975, between 80-85% of the asbestos consumed domestically was imported (see Sections 4.3 and 4.4); and of the imported asbestos, nearly 96% originated in Canada (Clifton, 1975). The milling segment of the industry is very closely connected to the mining segment r because-mills are usually located in close geographical proximity to the mines ' and, in general, the mines and mills are owned and operated by the same parent r- I corporation. American mining and milling production is discussed in Section 5.1. l The interesting relationship is, however, the relationship between the r l mining segment of the industry and the primary industries, the product manu- facturers who initially fabricate asbestos products. Table 3.1 lists the cap- [ tive fiber sources in Canada and in the U.S. for the major domestic asbestos [ products manufacturing firms. Twenty of the largest U.S. asbestos products manufacturers are listed in Table 3.2. When Tables 3.1 and 3.2 are compared, it [ can be seen that four corporations (Johns-Manville, Raybestos-Manhattan, Jim Walter, and ASARCO) not only control large mining interests in Canada, but also [ control nearly 35% of the American asbestos products market. l According to the 1967 U.S. Census of }mnufacturers, 81 firms operating 138 establishments were involved in asbestos products manufacturing (SIC 3292; L this does not include asbestos paper-making establishments). The 1972 Census of Manufacturers lists 142 establishments for SIC 3292. When the asbestos paper- r makers are included, it is estimated that approximately 85 firms are presently [ engaged in asbestos products manufacture (SRC estimate). In evaluating the asbestos products manufacturing industry, it is possible to arrive at the [ 21 FMSI 04857 Table 3.1. Captive Fiber Sources for the Major American Asbestos Product Manufacturing Firms (Igwe, 1974; Asbestos Magazine, Dec. 1975) Canadian Hines r Company Mine (Company) Fiber-Producing Capacity (short tons/year) ASARCO l Lake Asbestos of Quebec, Ltd. r Johns-Manville Products Corp. Canadian Johns-Manville Co., Ltd. Jim Walter Corp. Carey-Canadian Mines, Ltd. [ Raybestos-Manhattan, Inc. Cassiar Asbestos Corp. (partial interest) 150,000 835,000 200,000 110,000 [_ General Dynamics Corp. Asbestos Corp., Ltd. (54% interest) 500,000 [- I Atlas Asbestos Co. Union Carbide Corp. [ Johns-Manville Products Corp. American Mines Atlas Asbestos Co. Union Carbide ~lines Coalings Asbestos Co. 25,000 10,000 (closed at present) l [_ [ I_ 22 l FMSI 04858 Table 3.2. Twenty of the Largest U.S. Asbestos Product Manufacturers (Economic Information Systems, 1976; Igwe, 1974; SRC Estimates) Co nip a n y Estimated 1975 Asbestos-Product Sales ($ millions) 1. Johns-Manville Corp. 2. Raybestos-Manhattan, Inc. 3. GAF Corp. 4. Bendix Corp. 5. Jim Walter Corp. (Celotex) 6. Armstrong Cork Co. 1. Illinois Central Industries (Abex Corp.) 8. Flintkote Co. 9. Asten-Hill Mfg. Co. 10. H.K. Porter Co. 11. Certain-Teed Corp. 12. Nicolet Industries 13. Kentile Floors Inc. 14. National Gypsum Co. 15. Royal Industries 16. Uvalde-Rock-Asphalt Co. 17. Sabine Industries 18. American Asbestos Textile 19. ASARCO Inc. (Cement Asbestos Products) 20. Gatke Corp. 240 140 114 72.5 71 60 60 so 40.5 37.6 33.1 30.7 29.5 27.1 24.5 21.6 21.6 15.0 13.0 11.6 Approximate Percentage of the U.S. Market 18.0 10.5 8.5 5.5 5.5 4.5 4.5 3.5 3.0 3.0 2.5 2.0 2.0 2.0 2.0 1.5 1.5 1.0 1.0 1.0 23 FMSI 04859 r conclusion that the industry may be dominated by several giant firms. From Table 3.2 it can be seen that the six largest firms control over 50% of the market. It should also be noted that the larger asbestos-based manufacturing [ firms are generally diversified into other product lines. Table 3.3 shows the r. percentage of some major manufacturers' product lines that are related to asbestos. [ 'Table 3.3. Asbestos-Based Activity of Some Major Asbestos-Manufacturing Companies r (Igwe, 1974; SRC Estimates) Estimated Annual Sales Percent of Product Line L Company ($ millions) Related to Asbestos r American Biltrite Rubber Co. The Flintkote Co. 161 441 5 12 GAF Corp. 5 [ Johns-Manville Corp. National Gypsum Co. [ Jim Walter Corp. 800 519 880 30 5 8 r 3.2 rypes of Plants Asbestos products manufacturing plants are characterized by a high degree of specialization. The typical plant (especially of the minor manufacturers) is apt to be a single-product operation whose product is geared to service a specific industry. Table 3.4 lists the general statistics for 24 FMSl 04860 Table 3.4. Industry Specialization and Primary Product Class Specialization for Asbestos Product Producing Establishments: 1972 (SIC 3292) (1972 Census of Manufacturers, U.S. Bureau of the Census) [ Entire Industry I Primary Product Class Establishments Establishments with 75% or More Specialization 142 127 Friction Materials [ Asbestos-Cement Shingles and Clapboard ( Vinyl Asbestos Floor Tile I Asbestos and Asbestos-Cement Products 23 7 18 55 21 6 17 42 [ establishment specialization in 1972. In Table 3.4 the measures of plant I specialization are shown as: (1) industry specialization - the ratio of primary product shipments to total product shipments (primary plus secondary) and I (2) product class specialization - the ratio of the largest primary product class shipments to total product shipments (primary plus secondary) for the l. establishment. l A survey of selected facilities shows that nearly all the large plants employing in excess of 100 workers belong to the major firms within the industry, l such facilities also often generating relatively minor proportions of nonasbestos products (Igwe, 1974). 25 FMSI 04861 It is fair to state that the asbestos manufacturing industry in the United States is very mature, with most of the larger plants well over 25 years old and employing well-established technologies. For instance, asbestos-cement pipe manufacture was introduced in the United States about 1928 by the JohnsManville Corporation at its Waukegan, Illinois, plant. Except for incorporation of sophisticated controls and materials handling systems, it is doubt~ul whether the technology, similar iq principle to that employed in the manufacture of flat or corrugated sheeting,_ has changed to any fundamental extent since then. Similar comments may be applied to the manufacture of vinyl asbestos tiles (Igwe, 1974). 3.3 Numerical and Percentage Distribution of Plants, Employees,'and Production The numerical distribution of the establishments by size (expressed in terms of the number of employees) as given by the 1972 Census of Manufacturers is shown in Table 3.5. Total employment as a function of establishment size and [_ total value of shipments as a function of establishment size for asbestos products r manufacturing are given in Tables 3.6 and 3.7, respectively. I l A comparison of Tables 3.5 and 3.6 shows that whereas establishments with less than 100 employees account for 53.4% of the number of asbestos products manufacturing establishments, these facilities employ only 7.8% of the work force. The relative minor contributions of the "less-than-100-employees" facilities are further illustrated when Table 3.5 is compared to Table 3.7. The industry segment with less than 100 employees per establishment contributes only 6.1% of the shipment values of asbestos products. The economic punch appearH clearly to rest with the major manufacturing units. There is the additional consideration that, for a given asbestos product, the manufacturing equipment tends to be of a given standard capacity. 26 FMSI 04862 Table 3.5. Asbestos Products ~lanufacture: Distribution of Plant Sizes (1972 Census of Manufacturers (SIC 3292), U.S. Bureau of the Census) Average Number of Employees 1 to 4 5 to 9 10 to 19 20 to 49 50 to 99 100 to 249 250 to 499 500 to 999 1000 to 2499 Total Total Number of Establishments 12 20 13 16 15 40 19 5 2 142 Percent of Total 8.5 14.0 9.1 11.3 10.5 28.2 13.4 .3.5 1.4 Table 3. 6. Asbestos Products Hanufacturing: Total Employment as a Function of Size of Facilities (1972 Census of Hanufacturers (SIC 3292), U.S. Bureau of the Census) Average Number of Employees 1 to 4 5 to 9 10 to 19 20 tO. 48 50 to 99 100 to 249 250 to 499 500 to 999 1000 to 2499 Total * SRC Estimates Total Number of Establishments 40* 100 200 500 1,100 6,400 6,300 6,300 4,200* 25,140 Percent of Total 0.2 0.4 0.8 2.0 4.4 25.4 25.0 25.0 16.7 27 FMSl 04863 ~able 3.7. Asbestos Products Manufacturing: Total Value of Shipments as a Function of Size of Facilities (1972 Census of Manufacturers (SIC 3292), U.S. Bureau of the Census) Average Number of Employees il' 1 to 4 5 to 9 ,r 10 to 19 20 to 49 50 to 99 100 to 249 ll 250 to 499 500 to 999 1000 to 2499 Total 'l * SRC Estimate Value of Shiptoents ($ millions) 0.7 4.9 7.4 15.8 30.7 246.8 255.6 . 201.5 200.0* 963.4 Percent of Total o.s 0.8 1.6 3.2 25.6 26.5 20.9 20.8' Differences in plant capacities are therefore determined approximately by the number of installed machines, and capacity differences therefore occur in multiples of one standard machine capacity (Igwe, 1974). l rJ I J il jt 28 FMS' 04864 4.0 }1A.RKET INPUT/OUTPUT DATA The salient statistics for asbestos are graphed in Figure 4.1, which covers the period from 1940 to 1975. Import and e~~ort data shown in Figure 4.1 represent shipments of unmanufactured asbestos only. 4.1 Mine Production Table 4.1 lists the domestic and world mine productions from 1965 to 1975. U.S. mines shipped only 75% as much asbestos in 1974 as in 1973 and only 66% as much in 1975 as in 1973. The exact total output of 112,533 tons in 1974 was valued at $13,759,000 (Clifton, 1975). Only four states produce asbestos: California, with 53% of the 1974 total, was the leader, follm.;red in order by Vermont, Arizona, and North Carolina. The California segment of the asbestos industry has led the sharp decline in [ U.S. production. The closing, in early 1974, of Johns-Manville's (Coalings l Asbestos Co.) mine was followed by the closing of H.K: Porter's (Pacific Asbestos Corp.) mine. These mine closures led to production of only 57% of the 1973 [ - California state total, and only 55% of the 1973 dollar value of the fiber was realized (Clifton, 1975). The H.K. Porter mine was sold in October, 1975, to [ Calaveras Asbestos Ltd. and was to begin operation in mid-1976 (Asbestos Maga[ zine, December, 1975). All of the American mines produce the chrysotile variety of asbestos l except the North Carolina mines which produce the anthophyllite variety. In total, the American mines produce approximately 15% of the asbestos used in the L United States. The remainder is imported, mostly from Canada (see Section 4.3). l 29 FMSl 04865 THOUSANDS OF SHORT TONS APPARENT CONSUMPTION 100 [ [ lI I. 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 Figure 4.1. Asbestos - Salient Statistics (SRI, 1974; Clifton, 1974; U.S. Bureau of the .Census, 1975 a, b) 30 FMSI 04866 I .- -- - -r-- r-- ,...._... ,........ ,..._ ~ ,...._....., ,..._..., ----, I Table 4.1. Mine Production of Asbestos (Clifton, 1975; Asbestos Magazine, December, 1975) (Thousand sho~t tons) 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 World mine production: United States 118 126 123 121 126 125 131 132 150 llJ 99 .w..... RoMt of world 2,984 3,149 3,084 3,170 4,042 3,672 3,816 4,050 4,448 4,423 4,996 Total 3,102 3,275 3,207 3,291 4,168 3,797 3,947 4,182 4,598 4,536 5,095 , esn:: 0 ,J:Io. 0) .C.... 4.2 Exports Table 4.2 below lists the American export of asbestos (unmanufactured) from 1965 to 1975. Table 4.2. U.S. Export of Asbestos (Unmanufactured) for 1965 - 1975 (Clifton, 1975; U.S. Bureau of the Census, 1975 b) . Year 1975 1974 1973 1972 1971 1970 1969 1968 1967 1966 1965 Asbestos Export in Thousands of Short Tons 35 62 66 59 54 47 36 41 47 47 43 Tables 4.3a and 4.3b list the countries to which the exported asbestos (unmanufactured) was shipped in 1975 and in the first half of 1976, respectively, and the amounts shipped to each country. Unmanufactured asbestos includes asbestos fibers, not further processed than beaten, washed or graded to length and asbestos waste and refuse. Table 4.4 lists u.s. exports, by country, of asbestos manufactured products in 1975. In 1975 U.S~ exports of unmanufactured asbestos amounted to only 6.5% of the quantity of U.S. imports, while in 1974 the figure was only 8.1%. On the other hand, the dollar value of U.S. exports of manufactured asbestos products was nearly three times higher than the dollar value of U.S. imports of manufactured asbestos products. 32 FMSI 04868 Table 4.3a. U.S. Export --By Country -- of Asbestos (Unmanufactured) in 1975 (U.S. Bureau of the Census, 1975 b) 2764015 Asbestos fibers, not further processed than beaten, washed, or graded to length Net Quantity Value (Short Tons) (Dollars) Canada Mexico Brazil Belgium France West Germany Rumania Iran Singapore Japan Other Countries Total 1,567 6,881 699 463 206 937 494 721 1,137 1,334 734 15,173 682,546 2,349,846 261,080 140,181 204,242 335,709 101,420 252,817 523,255 . 936,115 279 2895 6,067,106 2764030 Asbestos waste and refuse Canada 3,629 Mexico 5,109 Colombia 706 Venezuela 391 Brazil 115 United Kingdom 815 France 458 West Germany 723 Italy 120 Iran 203 Singapore 615 Japan 3,842 Egypt 104 Other Countries 2,918 Total 19,748 188,856 1,151,572 124,078 70,978 67,123 131,681 101,436 202,087 72,414 . 78,240 577,569 700,350 64,558 460,943 3,991,885 *U. S. Bureau of the Census, 197Sb 33 FMS1 04869 r r I [ r l I I_ 1_ I l 1. Table 4.3b. U.S. Export -- By Country -- of Asbestos (Unmanufactured) from January, 1976, to June, 1976 (u.s. Bureau of the Census, 1976 b) 2764015 Asbestos fibers, not further processed than beaten, washed, or graded to length Net Quantity (Short Tons) Value (Dollars) Canada Mexico Venezuela Brazil United Kingdom The Netherlands Belgium East Germany Greece Rumania Iran Thailand Indonesia Taiwan Japan Algeria Other Countries Total 448 4,883 119 63 41 298 328 177 126 371 140 1,320 900 300 1,532 840 595 12,481 161,298 1,283,987 40,302 41,106 32,000 63,953 76,115 130,190 33,840 101,135 39,033 527,987 284,150 116,350 631,900 292,428 104!760 3,960,534 2764030 Asbestos waste and refuse Canada Mexico Colombia Venezuela Brazil United Kingdom East Germany Spain Italy Rumania United Arab Emirants Korean Republic Japan Algeria Libya Other Countries Total *u. S. Bureau of the Census, 1976b 255 5,430 445 ' 231 378 613 400 120 49 400 192 1,500 3,507 760 149 646 15,075 63,389 1,113,082 80,832 36,805 77,447 114,365 209,904 57,831 54,279 76,000 125,195 348,000 546,306 57,054 101,058 158,559 3,220,106 34 FMSI 04870 Table 4.4. U. S. Exports--By Country--of Asbestos Manufactured Products in 1975 * 66183+0 Asbestos-cement shingles and clapboard Net Quantity (Pounds) Value (Dollars) Canada United Kingdom West Germany Italy Saudi Arabia Japan Other Countries Total 669,126 589,890 17.778,767 7,205,759 228,577 234,704 1,847,108 28,553,931 142,466 109,149 2,97i,698 943,314 78,228 66,185 331 z776 4,648,816 6618320 Articles of asbestos-cement or of fiber-cement except asbestos cement shingles and clapboard' Canada Mexico Salvador Panama Brazil Sweden West Germany Iran Saudi Arabia Indonesia Philipine Republic Japan The Pacific Islands Algeria Republic of South Africa Other Countries Total 21,936,513 487,372 455,804 5,266,390 134,606 305,303 102,004 265,941 4,511,035 33,478 360,441 418,104 320,865 2,094,038 116,300 1,096,502 37,904,696 3,867,321 138,980 64,879 715,851 70,184 375,555 87,175 79,733 999,724 161,793 70,893 242,323 71,806 185,964 73,093 422,609 7,627,883 6638105 Asbestos gaskets l'Canada Jamaica Iran Saudi Arabia Republic of South Africa Other Countries Total 172,100 32,955 39,551 91,663 14,105 184,962 535,336 500,993 98,785 68,213 202,404 79,183 660,608 1,610,186 *U. S. Bureau of the Census, 1975b 35 FMSI 04871 ( 1 J Table4.4. u. s* Exports--By Country--of Asbestos ~mnufactured Products in 1975 (Cant' d) '{ Net Quantity Value (Pounds) (Dollars) l 6638115 Asbestos packing 2 Canada 1,042,869 1,896,802 :I Mexico Guatemala Jamaica 393,093 25,828 49,803 291,741 68,294 278,425 Colombia 320,649 513,348 Venezuela 37,695 158,526 Surinam 42,645 142,790 Peru 151,358 396,141 l Chile Brazil Sweden 123,234 114,892 15,451 205,258 119,524 94,047 I Finland United Kingdom Ireland 30,289 264 J 110 81,400 279,984 374,256 366,739 r The Netherlands Belgium France 15,083 20,239 41,1.89 113,214 139,314 177,591 tiest Germany 76,187 205,023 I Switzerland Spain Italy 17,857 30,531 86,309 80,840 183,812 673,373 Greece 25,198 73,157 Iran 46,118 137,128 Israel 9,577 95,091 Kuwait 16,468 80,943 Saudi Arabia 466,441 256,331 India 145,126 64,691 Pakistan 13,920 64,832 I Thailand Singapore l?hilippine Republic 42,989 153,448 229,895 76,663 408,972 551,008 Korean Republic 27,000 63,030 [ Tail.ran Japan 52,596 57,871 159,405 262,573 Australia 28,394 131,979 ll New Zealand Nigeria 25,210 33,470 170,069 87,997 I Republic of South Africa 35,719 242,818 I Zambia Other Countries Total 11,917 3462981 4,749,049 118,528 987 2008 10,791,265 *u. s. Bureau of the Census, 1975b 36 FMSI 04872 I f I Table 4.4. U. S. Exports--By Country--of Asbestos }lanufactured Products in 1975* (Cont'd) I Net Quantity (Pounds) Value (Dollars) I 6638117 Asbestos insulation, heat or sound 2 Canada 729,888 Mexico 188,096 1 Dominican Republic Venezuela 60,990 282,149 Surinam 282,149 I Peru Brazil 81,658 214,532 United Kingdom 130,610 I The Netherlands Belgium Iran 102,618 253,755 66,323 Pakistan 143,518 1 Singapore Philippine Republic 364,906 74,620 Mainland China 916,153 l Japan Australia New Zealand 98,572 99,706 248,444 l Egypt Ghana Other Countries 68,333 65,383 812,154 Total 5,071,672 6638120 Asbestos textiles and yarns I 3 Canada Hexic.o _7,749,305 1,249,110 3,664,189 747,770 Peru 122,520 220,267 i Sweden 'United Kingdom 122,929 85,929 230,746 207,598 Ireland 45,100 145,350 l The Netherlands West Germany 487,222 195,984 127,799 252,944 Italy 54,043 274,700 I Japan Australia 23,646 1,020,703 146,510 614,452 Other Countries 307,061 651,974 Total 11,463,552 7,284,299 1 *U. S. Bureau of the Census, 1975b I 37 l FMSl 04873 ' Table 4.4. U. S. Exports--By Country--of Asbestos Manufactured Products in 1975* (Cont'd) Net Quantity Value (Pounds) (Dollars) [ 6638150 Asbestos protective clothing Mexico Greece I Saudi Arabia Other Countries Total 76,580 200,311 68,643 463,975 809,509 I 6638160 Asbestos manufactures, other than friction materials, NEC l Canada Mexico Panama I Jamaica Venezuela Peru I Chile Brazil Sweden I United Kingdom The Netherlands West Germany Switzerland I Poland Lebanon Iran I Saudi Arabia Korean Republic Japan 1 Australia New Zealand 'Republic of South Africa Other Countries I_ Total 2,230,745 246,573 74,099 70,179 749,761 305,139 182,659 83,043 1,145,722 2,528,018 702,650 866,848 124,542 81,315 83,372 66,238 185,369 110,313 439,217 92,913 200,613 325,572 845,089 1~,739,989 I I *U. S. Bureau of the Census, 1975b I 38 I FMSI 04874 Tabla 4.4. U. S. Exports--By Country--of Asbestos Manufactured Products in 1975* (Cont'd) Net Quantity Value (Pounds) (Dollars) 6638202 Asbestos clutch facings for automotive use, including linings Canada Chile United Kingdom West Germany Other Countries Total 506,277 63,447 195,978 226,888 281,518 1,274,108 6638206 Asbestos clutch facings, NEC, including linings Canada Other Countries Total 160,905 163,144 324,049 6638215 Asbestos brake linings for automotive use 1 Canada Guatemala Ecuador Chile Belgium Greece Lebanon Iran Singapore Indonesia Other Countries Total 5,726,553 55,287 76,894 26,188 83,388 426,808 146,100 164,803 133,140 118,415 700,518 7,658,094 4,681,018 95,364 114,637 63,495 133,965 177,068 165,735 156,894 82,093 73,897 8691554 6,613,702 6638225 Asbestos brake linings, NEC 6 Canada Mexico Brazil The Netherlands Japan Australia Other Countries Total *u. s. Bureau of the Census, 1975b 1,487,000 274,572 20.913 26,700 15,909 48,975 1801307 2,054,376 1,594,737 173,896 148,892 271.849 64,690 136,347 3691465 2,759,876 39 FMSl 04875 4.3 Imports Table 4.5 below lists the American imports of asbestos (unmanufactured) from 1965 to 1975. [ [ r [ r I II l [_ r l [ I_ Table 4.5. U.S. Imports of Asbestos (Unmanufactured) for 1965 - 1975 (Clifton, 1975; U.S. Bureau of the Census, 1975 a) Year 1975 1974 1973 1972 1971 1970 1969 1968 1967 H~ H~ Asbestos Import in Thousands of Short Tons 539 766 792 736 682 649 695 737 646 1W 1H In 1975, 539,000 short tons of asbestos were imported into the U.S., as compared to 766,000 short tons in 1974. The decrease from 1974 to 1975 was due to a shortage of asbestos in the Canadian supply caused by: 1) a destructive fire a~ Thetford Mines, Quebec, 2) a landslide at Johns-Manville 1 s Jeffrey M1ne, Quebec, and 3) the 7-month-long strike of Quebec asbestos workers (Asbestos Magazine, December, 1975). During the first half of 1976, 329,000 short tons of asbestos were imported, a rate which is approximately midway between the 1974 and 1975 figures. 40 FMSI 04876 Tables 4.6a and 4.6b list U.S. imports, by country, of unmanufactured asbestos in 1975 and the first-half of 1976, respectively. Table 4.7 gives similar data for 1973- 1974. Table 4.8 lists U.S. imports, by country, of manufactured asbestos products in 1975. A historical breakdown for asbestos imports of chrysotile, crocidolite, and amosite is included in Table 4.9, l Asbestos Supply-Demand Relationships. During the entire history of the asbestos industry in the U.S., lr domestic sources have been able to meet only a small percentage of U.S. require- ments. Canada furnished 96% of all the asbestos tonnage imported by the U.S. (1969- 1973), but only a small portion (3%) was spinning grade fibers. The [ comparatively small tonnages imported from Africa are more important than would appear on a tonnage basis because they consist largely of special kinds and r qualities unobtainable elsewhere (Clifton, 1975). [ 4.4 Supply-Demand-Use Table 4.9 gives the asbestos supply-demand relationships for [ 1965 - 1974. The U.S. supply is a combination of imports, domestic mine pro- duction, industry stockpiles, and governmental stockpile releases. The U.S. r ! supply is distributed among industry and governmental stockpile acquisitions, [ exports, and industry demand. The relative importance of each is apparent from Table 4.9. The asbestos distribution by end use, grade, and type for 1974 is [ shown in Table 4.10. The major buyers of asbestos and asbestos ore are listed in Table 4.11. [ 4.5 Asbestos Fiber Prices l Asbestos prices are characterized by an erratic price history. Prices for Canadian asbestos increased about 8% in 1973, 39% in 1974, and 23% in 1975 ( 41 FMSI 04877 l f ( Table 4.6a. U.S. Imports--by Country--of Unmanufactured Asbestos in 1975 Net Quantity [ I 1Short Tons Customs Value (dollars)** F.a.s. C.i.f. [ 2764010 Rep SAP Asbestos, Amosite 3,894 1,539,951 1,542,143 1,872,035 Total 3,894 1,539,951 1,542,143 1,872,035 [ 2764020 Asbestos, Crocidolite, Blue Mozambq 118 16,090 16,090 29,033 Rep SAP 11,570 4,942,886 4,942,181 6,100,733 [ Total 11,688 4,958,976 4,958,271 6,129,766 2764030 Asbestos, Chrysotile Crudes [ Canada U King 71 9,045 9,654 9,654 277 82,982 82,982 121,299 Belgium 22 2,670 2,670 4,408 USSR 4,525 920,772 920,772 1,617,748 [ Rep SAF Swazlnd 940 2,756 663,658 952,544 663,658 952,544 760,556 1,291,259 Rhodesia 1,633 1,521,421 1,520,611 1,753,361 Total 10,244 4,153,092 4,152,891 5,558,285 [ 2764040 Asbestos, Chrysoti1e, Except Crudes and Spinning Fibers Canada 7,637 5, 772,397 5,879,920 5,893,666 lr Rep SAF Rhodesia 115 99,572 99,572 109,296 382 368,845 368,845 414,831 Total 8,134 6,240,814 6,348,337 6,417,793 2764050 Asbestos, Chrysotile, Except Crudes and Spinning Fibers Canada 490,615 91,014,320 96,411,691 96,526,478 Mexico 73 14,876 14,876 14,876 U King 58 11,396 11,890 11,890 USSR 86 38,640 39,805 40,214 Italy 44 12,540 12,540 16,461 Gaza St 152 25,914 25,914 25,.914 Rep SAF 220 68,025 68,276 95,123 Rhodesia 32 22,871 22,871 27,614 Total 491,280 91,208,582 96,607,863 96,758,570 L 2764060 Asbestos, Unmanufactured, Crudes, Fibers, Stucco, Etc., NES Canada Finland Belgium USSR Italy Rep SAF Rhodesia Total 5,222 329 48 5,768 153 1,237 576 13,333 776,931 32,841 4,599 1,321,982 23,868 391;099 357,486 2,908,806 858,340 32,298 4,599 1,321,982 23,868 424,487 357,486 3,023,060 859,639 51,915 7,426 1,822,332 38,805 533,022 473,331 3,786,470 *Source: U.S. Bureau of the Census, 1975a **Customs Value: Value of imports appraised by U.S. Customs Service. F.a.s. Value: Transaction value of imports at foreign port of exportation. C.i.f. Value: Value of imports at the first port of entry in U.S. 42 FMSI 04878 Table 4.6b. U:S. Imports--by Country--of-Unmanufactured Asbestos, January to June, 1976* . , 2764010 Rep SAF Oth CtyTotal Net Quantity Short Tons Customs .Asbestos, Amosite 1,151 20 1,171 503,663 469 504,132 Value (dollars) I IF.a.s. 509,697 669 510,366 C.i.f. 642,607 669 643,276 2764020 Asbestos, Crocidolite, Blue Rep SAF Total 4,712 4, 712 2,315,466 2,315,46"6 2,388,971 2,388,971 2,606,013 2,606,013 2764030 Asbestos, Chrysotile Crudes Canada Mexico U Kin~ Rep SAF Rhodesia Total 289 234 119 351 1,095 2,088 125,175 125,486 55,992 193,918 1,115,230 1,615,801 129,108 126,948 55,992 193,913 1,115,230 1,621,196 129,108 126,948 64,090 220,191 1,200,965 1,741,302 2764040 Asbestos, Chrysoti1e Spinning Fibers L - Canada Total 2,394 2,394 2,053,568 2,053,568 2,110,240 2,110,240 2,111,611 2,111,611 2764050 Asbestos, Chrysoti1e, Except Crudes and Spinning Fibers Canada Fr Germ Rep SAF Oth C"ty [ Total 298,988 1,086 396 17 300,487 60,006,713 202,826 217,440 3,919 60,430,898 63,427,681 202,826 219,660 3,919 63,854,086 63,598,407 257,094 235,599 3,919 64,095,019 2764060 Asbestos, Unmanufactured, Crudes, Fibers, Stucco, Etc., NES r I L_ Canada 8,759 1,450,342 1,571,118 1,572,326 Fr Germ 823 179,840 179,840 320,577 r USSR Rep SAF L Oth Cty 6,700 1,953 54 1,292,721 898,889 21,969 1,293,001 920,675 22,029 2,079,238 981,292 22,368 Total [ 18,289 3,843,761 3,986,663 4,975,801 *Source: U.S. Bureau of the Census, 1976a r L 43 FMSI 04879 r r l r I [ I r I I [ I l [ I l l Table 4. 7. U.S. Imports for Consumption of Asbestos (Unmanufactured) by Class and Country (Clifton, 1974) Year and country - - - - - - - - - - - -Crude (lnolud- lna blue tiber) Textile tiber All other Quantity Value Quantity Value Quantity Value (abort. (thou- (lhort. (thou- (short. (thou- tonal oanda) tono) sandal tonal aanda) Total Quantity Value (abort. (thoutoni) aanda) 11173 Canada ---------------Finland ---------------Germany, Weet -------- Guyana ---------------- IMtaallyasa-a-y-,--R-e-p-u--b-li-c---_-. -__- Mexico ---------------Moumblque ----------- PPoartn.au~m~;aal ------ ----------------------- Rhodeaia, Southern ---- South Africa, Republic of ____ ______ Swaziland ------------- Yemen ---------.-----YUKoslavla ------------ 1,991 78 U a45 21,629 200 1397 __ 21 27 423 4,610 122 16,666 86,020 81 130 73 7.S,Il88 1,027 __ sos 88 n li 12 1 $86,U9 83 18a 'I 1 11 (') 7U,&U 1.027 78 aoa a8 (8 16 lll 1 U6 $92,866 91 21 8 1 'J, 118 11 (I) 428 8,427 60 8 733 21,064 I,!U sao 195 11 liO 11 8 - - -8- - -8 Total _-- __ -------==2:=4=:,7=9&===6==60:,::0==15=::;80=3==':=0=9=4=='=7=61::::=:87=5=::::8:=7::;,1=20:::=:=7::;11::;2:'=:"3:::=:::::9:,::8::,9=:1:::4 1874. ~!:!~. -=============== Finland --------------- Germany, Weat -------- Italy ------------------ KPoerxtuic~oral - --------------------------- _ RSohuotdheaAlafric-a-,------------ Republic of ---------- Swadland ------ _------ U.S.S.R -------- ------- 11_5_ 119 -1,717 20.807 480 i_3_ 80 -1,010 &,167 361 26,7&8 10,4i6 20 712,228 667 1 lili ' 2 106,085 74 1 ii 2 8,291 1110 4&1 123 20 189,111 157 100 1 611 4 1,721 2 116.1114 74 86 '11 2 1.012 23,66o& 480 01 6,881 861 128 Total ------------ 22,718 6,576 26.839 10,488 716,807 1_06.808 766,164 128,822 ' Leaa than Yo unit. 44 FMSI 04880 Table 4.8. U.S. Imports--by Country--of Manufactured Asbestos Products in 1975* 6618340 Net Quantity Pounds Customs Value (dollars) I F.a.s. -~ Asbestos & Hydraulic Cement Articles NES C.i.f. Canada Mexico Guatmal Colomb U King Belgium W Germ Japan Austral Total 12,176,880 282,803 532,566 15,259,038 9,246 7,395,456 4,149,943 145,941 246,333 40,198,206 1,700,400 73,555 43,941 1,494,207 5,350 1,858,386 377,706 30,725 '56,234 5,640,504 1,773,749 73,564 43,941 1,494,215 5,368 1,858,022 377,705 30,725 59,555 5,716,844 1, 773,779 73,564 60,097 1,760,082 5,995 2,168,971 564,244 36,848 70,473 6,514,053 6638000 Asbestos Articles, NES, and Asbestos Yarn, Sliver, Rope, Etc., With or Without Wire Canada Mexico Venez Brazil Sweden Norway Finland Denmark U King Neth1ds Belgium France W Germ Switzld Spain Italy Yugos1v Greece India Phil R Kor Rep China T Japan Rep SAF Total ' 3,988,524 2,624,027 40,381 841,938 128,742 6,369 8,499 12,780 4,373,180 11,139 32,774 137,475 1,282,955 6,187 495,545 156,022 17,664 1,140 5,261 1,000 257,256 1,094,659 1,149,464 119,527 16,792,508 4,010,223 2,478,821 40,381 831,938 128,721 6,369 8,499 12,189 4,380,595 11,139 32,795 137,897 1,278,071 6,187 495,545 156,022 17,664 1,140 5,261 1,000 244,970 1,075,207 1;135,904 119,527 16,616,065 4,019,687 2,617,067 42,674 872,701 142,887 7,749 9,149 12,594 4,794,464 11,578 35,867 147,444 1,346,141 7,168 531,694 172,358 19,251 1,226 5,919 1,555 255,633 1,154,996 1,228,451 120,127 17,558,380 *Source: U.S. Bureau of the Census, 1975a 45 FMSI 04881 ------------------------------------------- I --- - --,..... ,......_ ,...... .~ ~ ,_.,.. '~ ~ ~ ,_..., ,........... ~.... I Table 4.11. Buyers of Asbestos and Asbestos Ore (Compiled from data furnished by I U.S. Bureau of Mines, Washington, D.C.) Armstrong Cork Co., West Liberty & Charlotte St., Lancaster, Pa. 17604 Asbestos Textile Co., 165 West Wacker Dr., Chicago, Ill. 60601 Carlisle Corp., 621 North College, Carlisle, Pa. 17013 Celotex Corporation, L'Anse, Mich. 49946 I Certain-Teed Products Corp., 120 East Lancaster Ave., Ardmore, Pa. 19003 Firestone Tire & Rubber Co., 1200 Firestone Pky., Akron, Ohio 44317 Flintkote Co., The, Inc., 400 Westchester Ave., White Plains, New York 10604 Foseco, Inc., 20200 Sheldon Rd., Brook Park, Ohio 44403 GAF Corp., 140 West 51st St., New York, N.Y. 10020 Garlock Inc., 250 Main St., Palmyra, N.Y. 14522 Gatke Corp., Box 308 East Winona, Warsaw, Ind. 46580 Rooker Chemical Corp., Kenton, Ohio 43326 International Vermiculite Co., Girard, Ill. 62640 Johns-Manville Corp., Greenwood Plaza, Denver, Colo. 80217 .~.... Mead Corp., 118 West First St., Dayton, Ohio 45402 Minnesota Mining & Mfg. Co., 3M Center, St. Paul, M:J.nn. 55101 National Gypsum Co., Inc., 325 Delaware Ave., Buffalo, N.Y. 14202 Owens-Corning Fiberglass Co., Berlin, N.J. 08009 Pittsburgh Corning Corp., No. 1 Gateway Center, Pittsburgh, Pa. 15207 H.K. Porter Co., Inc., 601 Grant St., Pittsburgh, Pa. 15219 Raybestos Manhattan, Inc., Bridgeport, Conn. 06601 Rogers Corp., Rogers, Conn. 06263 Standee Brake Lining Co., 2701 Clinton Dr., P.O. Box 93, Houston, Tex. 77020 U.S. Gypsum Co., 101 South Wacker, Chicago, Ill. 60606 U.S. Plywood Corp., South River, N.J. 08882 -n 3C ~ 0 ~ 00 N Table 4.12 lists the average annual asbestos price from 1954 to 1974 and compares it to a figure based on constant 1973 dollars. Table 4.13 lists recent prices for various grades and origins of asbestos. The remarkable disparity of grade prices is evident from Quebec chrysotile fiber prices. Grade No. 7 (shorts) was priced at $89 per ton, while Grade No. 1 (crudes) cost $3496 per ton. 4.6 Future Outlook The best projections for future use of asbestos are reported by [ Clifton (1975). The information and projections contained in this subsection [ come directly from Clifton (1975). The domestic demand for asbestos is expected to increase at a slow [ rate; the low rate of annual growth is expected to be 0.9%, while thft high rate is expected to be 3.0%. The U.S. demand for asbestos in the year 2000 is pro- f jected to be about 1.25 times that of 1973 (876,000 short tons). Projection [ trends for the U.S. demand are illustrated in Figure 4.2. The forecast for U.S. demand of asbestos by end use is given in Table 4.14. ( U.S. ASBESTOS DEMAND 93~ / / [ 900 / / / / 873 ,~::-,.. // / .....8...7..7 ( ".0z.....'... ..0 X .,../...(._","".'.."..."......\'6'~.,.,...... "'800 l az c ":I' "0 ....... l. ...X LEAST SQUARES PROJECTIONS: (A) LAST 20-YEAR TREND IBI LAST 10-YEAR TREND [ 700 [ 19S4 1973 2000 BUREAU OF MINES ( U.S. DEPARTMENT Of THE INTERIOR Figure 4.2. U.S. Asbestos Demand, and Projected Trends to 2000 (Clifton, 1975) l 48 FMSI 04883 Table 4.12. Time-Price Relationship for Asbestos (Clifton, 1975) l Average Annual Price, Dollars Per Short Ton [ Year 'I 1954 l[ 1955 1956 1957 1958 I 1959 ( 1960 1961 1962 [ 1963 1964 1965 ,f 1966 1967 1968 :I 1969 1970 1971 1972 .,( ! 1973 1974 l l Actual Price 82.34 84.61 89.78 88.09 90.50 91.17 94.62 95.60 94.85 92.44 98.70 97.92 100.63 101.91 98.93 110.03 115.64 117.54 116.63 122.22 122.27 Constant 1973 Dollars 141.72 143.65 147.42 139.38 139.66 138.35 141.44 141.00 138.26 133.00 140.00 136.38 136.35 133.74 124.75 132.41 132.01 128.32 123.16 122.22 110.90 !I 'i i 1l lj[, 1II I 49 l FMSI 04884 Table 4.13. Recent Prices of Various Asbestoses (Asbestos Magazine, December, 1975) ARIZONA Per Ton of 2000 Lbs .. As of April 17, 1975 No. 1 Crude (Sofl) .. No. 2 Crude (Soft) .. AAA ........... .. .. .. . .. . . Group No. 3-Nonferrous Filtering-Plastic Group No. 4-Nonferrous Filtering-Plastic Group No. 7-While Shorts F.O.B Globe, Arizona U.S. Dollars $ $2000.00 1500.00 1100.00 715.00- 800 00 700.oo- 800.00 100.00- 200.00 QUEBEC As of December t, 1975 Per Ton of 2000 Lbs. F.O.B. Mine Canadian Dollars [ No. 1-Crude No. 2-Crude No. 3-Spinning Fiber No. 4-Asbestos Cement Fiber No. 5-Paper Fiber No. 6-Paper and Shingle Fiber lllo. 7-Shorts . . . $ . . $3496.00 1899 00 891 .00- 1463.00 492.00- 829.00 278.00- 392.00 236.00- 244.00 89.00- 198.00 CASSIAR Per Ton of 2000 Lbs., F.O.B. North Vancouver, B.C. As of August 1, 1975 Canad1an Dollars Cassiar Mine C-1 .. . .. .. AAA Grade-Nonferrous Spinning Fiber/Canadaan Group 3 $2916.00 1685.00 AA Grade-Nonlerrous Spinning FibertCanadian Group 3 A Grade-Nonferrous Spinning Fiber/Canadaan Group 3 AC Grade-Nonferrous Spinning Fiber/Canadran Group 3 AK Grade-Asbestos Cement Fiber/Canadian Group 4 AS Grade-Asbestos Cement Fiber/Canadaan Group 4 AX Grade-Asbestos Cement Fiber/Canadian Group 5 AY Grade-Asbestos Cement Fiber/Canadian Group 5 AZ Grade-Asbestos Cement Fiber/Canadian Group 6 1340 00 1020.00 735.00 524.00 454 00 416 00 292 00 216.00 [ Climon Mine CP Grade-Asbestos Cement Fiber/Canadian Group 4 CT Grade-Asbestos Cement Fiber/Canadian Group 4 CY Grade-Asbestos Cement Fiber /Canadian Group 5 492.00 445.00 292.00 [ CZ Grade-Asbestos Cement Fiber/Canadian Group 6 216 00 VERMONT Per Ton of 2000 LbS., F.O.B. Morrisville, Vermont As of January 1, 1976 U.S. Dollars Grade 4T-Fiber . . . . . .... S ..-$ 418.00 [ Grades 50 thru SA-Fiber Grade 60-Waste . . . . 275.00- 324.00 200.00 Grades 70 thru 7T-Sh0rts 83.00- 160.00 Grade 7TF-Fioats (Shol'ts) Grade BS-Shorts . ... Hooker No. 1-in 50-lb. woven poly bagsf eft. 1211175 72.00 54 00 970.00 Hooker No. 2-in 100-lb. woven poly bags/eff 1211/75 485 00 l [. [ ( so FMSI 04885 I [ I I Table 4.14. Projections and Forecasts for U.S. Asbestos Demand By End Use, ( 1973 and 2000 (Thousand short tons) (Clifton, 1975) I 2000 I End Use 1973 Contingency Forecasts for United States Forecast Range I Forecast Base Probable Low High ( Asbestos cement pipe 166 I Asbestos cement sheet Flooring products Roofing products 64 218 87 Packing and gaskets l Friction products Insulation 26 79 26 Paper 18 [- Textiles Other 18 174 475 178 479 190 100 65 104 68 360 233 372 236 150 93 148 94 75 64 75 66 150 110 144 118 30 30 39 34 45 21 40 27 20 19 24 21 400 199 387 260 I Total 876 1,012 1,812 1,114 I 1 [ l I 51 I FMSI 04886 [ 5.0 MINING AND MILLING ( 5 .1 U-.S. Mines and Mills Although asbestos deposits are located throughout the United States r (Figure 5.1), asbestos is mined in only a few states. The map in Figure 5.2 designates the location of mines which are operating or which have been closed [ recently. In order of decreasing annual production, the mining states are California, Vermont, Arizona, and North Carolina. Table 5.1 lists the American mines which are operating or have recently closed, along with the associated r .mills. All of the mines produce chrysotile asbestos with the exception of the Powhattan mine in North Carolina which produced anthophyllite asbestos. r The largest mines are the Vermont Asbestos Group mine (formerly owned [ by GAF Corp.) in Vermont and the Calaveras Asbestos Ltd. mine (formerly controlled by H.K. Porter Co.) in Copperopolis, California (Asbestos Magazine, [ December, 1975). The inactive Coalinga Asbestos Co. mine (Johns-Manville) was .the second largest mine in California and the third largest nationally. En- [ - vironmental regulations are cited as the prime reasons for the closing of the [ Johns-Manville mine (Clifton, 1976; Harwood and Blasznak, 1974; Asbestos Magazine, December, 1974, 1975). Although the Powhattan mine in North Carolina was re- l. ported as inactive since 1973 (Harwood and Blasznak, 1974), a conversation with a Powhattan employee suggests that the mine is currently being operated. L Potential mining has been discussed for Alamore, Texas (tremolite asbestos), Sonora, Ca~ifornia, and the Yukon region of Alaska (Asbestos Magazine, ( December, 1972, 1974). l It should be noted that actual mining production data for each mine cannot be accurately collected for proprietary reasons. Since California had, ( 52 ( FMSI 04887 ~'-"'---'<~< ...... ....... .....''"----~-----~""~'' J-111111' . . . . . . . ..~ '~-~----~~.,~-- ~~"-~- ~~.....,.__~ ~--~.------- -~~""~-~--,~------"'-''""'------- ..w~'-'"'-~-~~----~---- ......., ,.....,. - - - - - - - - -~ ,..._.. ~ ,....._ Uwl ~ Areas of the U.S. wht., '"'Cf contain natural oecurren~u of os:>esliform minerals u-: be~rock (areas containing igneous or metamorphic rocks) '"T1 -!: C/) 0 ~ Figure 5.1. Possible Areas of Asbestos Deposits (Harwood and Blasznak, 1974) 00 00 ::J I "".....''.. "<'( 0 Currently Operating A Recently Closed l l [ Figure 5.2. Asbestos Mines in the United States [ I l 54 FMSI 04889 ----""____,_._____________________________ ,_...._.... \.11 \.11 ., -3en: 0t CD 0 ,..........,. ,._.....-. r---"" ,............. ...--, ,.._..... ..------. Table 5.1. American Asbestos Mines and Mills (Harwood and Blasznak, 1974; Clifton, 1974, 1975; Asbestos Magazine, December, 1972 - 1975) Note: All mines are open pit except those in Arizona, which are underground. Operating Company Mine Location 1. Atlas Asbestos Co. 2. Calaveras Asbestos Ltd. 3. Union Carbide Fresno County, Calif. Calaveras County, Calif. San Benito County, Calif. 4. Coalinga Asbestos Co., div. of Johns-Manville 5. Vermont Asbestos Croup Fresno County, Calif. Hyde Park, Vt. 6. Jacquays Mining Corp. Gila Cuunty, Ariz. 7. ABbes tos tlf g. Co. a. Metate Asbestos Co. Gila County, Arb. Gila County, Ariz. 9. Powhattan tUning Corp. Burnside, N.C. * 1973 figures (llarvuod and Blasznak, 1974) ** Mill capacity figure Employees* Mill Location Estimated Production Employees* (Short Tons) Comments 20 Coalinga, Calif. 50 25,000/yr. Used in vinyl-floor tile 36 Copperopolis, 135 220/day Used in asbestos-cement Calif. pipes and sheets 36 King City, Calif. 50 110/day Used in reinforcing thermoplastics (Calidria); Japan is a major consumer 20 Coalinga, Calif. 50 110/day Closed in June, 1974 58 Hyde Park, Vt. 143 220/day Used in heat-resistant materials, mostly by CAF; purchased in 1975 from CAF 8 Globe, Ariz. 5 3,000/yr. Used for electrical and filter media; moat is exported to Japan -- ---Clobc, Ariz. Closed Closed -- ---Globe, Ar 1z. Closed Closed 4 Baltimore, Md. 8 700/yr.** -------- until recently, several operating mines, the Bureau of Mines has reported annual production for the state. But as a result of recent mine closings, the annual California production report might be terminated (Clifton, 1976). Table 5.1 contains estimates of Harwood and Blasznak (1974) for several indi- vidual daily mine productions and the estimate of Asbestos Magazine for annual [ production of two mines. Based upon the combined data of Harwood and Blasznak, Clifton; and Asbestos Magazine, we estimate that at the present time about 55-65% r of the asbestos mined in the U.S. is mined in California, 35-45% comes from Vermont, and less than 5% is mined in Arizona and North Carolina. Until recent mine closings and sales altered the California production, California had accoun- [ ted for nearly 70% of the domestic fiber. The lower limit for economical asbestos production is estimated at 4% I asbestos containing ore (Berger and Oesper, 1963) . Clifton (1975) evaluated the [ effect of continuous mine operations on the percent fiber recovery by a linear regression analysis of Quebec mine data (see Figure 5.3). He forecasts that as ( _ the age of a mine increases, the percent fiber recovery decreases. This will result in an increasing fiber production cost until mining is no longer prof- r itable. By reason of analogy, the Quebec data should be generally true for U.S. [ mines, especially the Vermont mine, which is an outcrop of the Quebec deposits. Based on the above data, the Vermont mine appears close to being mined out. [ 5.1.1 Ore Characteristics The chrysotile asbestos content of ore varies between deposit l locations. The lowest concentration is deposited in the Vermont ore which ( consists of less than 4% asbestos by weight, and the highest concentration is deposited in the Coalinga, California, district which is approximately 60% by l weight asbestos. I 56 FMSI 04891 i l I ::J 200 ------------------------------------------~20 (I ~ ...... QUEBEC PRODUCTION TRENDS .,~ :I N < ,"" ,,/ / I ."0.z..'.. Ill: 0 % 100 "z' 0:_::,; '~~Q/ / q..oc..,",~-.-.~/'>"" ,, / / "0 m ""10 ('\ mz -4 i REcovERy (Rock MILLED) / ROC"ff,\\.\.EO _Ob.----a---~--.-masm ____._.aa_.. . . . . .a.nO 1950 1960 1970 1980. 1990 2000 1 Ore and waste rock exclusive of overburden BUREAU OF MINES U.S. DPARTMENT Of THE INTERIOR I [ Figure 5.3. Quebec Production Trends, From Analysis of 1951- 1970 Data (Clifton, 1975) I f :I 57 jl FMSI 04892 The Vermont ore deposit is an outcrop of the large Quebec deposits in Canada. While the Vermont deposit contains some spinning grade fibers (Harwood and Blasznak, 1974), most fiber is shorter grade and is consumed in the manufacture of heat resistant products (Asbestos Magazine, December, 1973). The Calaveras Asbestos Ltd. mine in Copperopolis, California, [ produces the normal long fibered form of chrysotile asbestos which is primarily I used in asbestos-cement products (Harwood and Blasznak, 1974; Asbestos Magazine, December, 1975). Three mines, the.Coalinga (Johns-Manville), Atlas, and Union l Carbide, are in close proximity to each other near Coalinga, California. They work an ore body which is 10 miles long and 0.25 miles wide. The ore from these I mines is atypical of asbestos. Instead of a fibrous vein structure, the asbesI tos is in a platy, slippery form known locally as desert leather (Harwood and Blasznak, 1974). The fibers from this tract are short and therefore are used in l floor tile and reinforced thermoplastics (Asbestos Magazine, December, 1971, 1975). Arizona produces an exceptionally high quality, low iron content asbes- I tos, most of which is used for electrical insulation and for filtering media (Asbestos Magazine, December 1975). Most of the Jacquay Mine production is I exported to Ja~an (Harwood and Blaszak, 1974). I_ 1 \ I I. 58 FMSI 04893 l 6.0 FRICTION MATERIALS Friction materials are used in practically all industries as a key component I in clutches for transmitting torque, brakes for slowing down or stopping motion, I or as torque limiters. Although friction applications to automobile brakes and clutches are the most important commercially, asbestos-friction applications are ( not limited to brakes and clutches in automobiles, trucks, busses, construction equipment, and railroad cars. Rather, these applications are found wherever I motion must be controlled. The following examples show the diversification of I friction material usage: farm tractors, presses, hoists, tensioning devices in production of wire and plastic rope and cable, lift trucks, machine tools, I shuttlecars, specialized mining equipment, chainsaws, drilling equipment, spin- ning and knitting equipment, x~ray machines, wheel brakes, tape recorders, I typewriters, bicycle brakes, snowblowers, and washing machines (Daly et al., I 1976). Asbestos is an important ingredient in these friction material products because it imparts strength, good friction properties, can withstand high tern- peratures, and is a good insulator. 6.1 Statistics 1 6.1.1 Use Quantity and Shipment Values I From Table 4.9 (p. 46), it can be seen that U.S. demand for asbestos in friction products has ranged from sixty-five to eighty thousand l short tons annually from 1964 to 1974. This amounts to approximately 9% of the total u.s. asbestos demand (consumption). The trend in the value of shipments of asbestos friction materials I is shown in Table 6.1. Duri~g the five year period from 1967 to 1972, shipment I 59 l FMSI 04894 ---~- -,..-.-. ,...._ r---" ..----. Table 6.1. Value of Shipments of Asbestos Friction Materials (U.S. Bureau of the Census, 1972 Census of Manufacturers) SIC Product Code Product 32922 - 32922 11 32922 15 Asbestos Friction Materials - Total Brake Linings: Woven, containing asbestos yarn, tape, or cloth Molded, including all non-woven types 32922 21 Disc Brake Pads C\ 0 Clutch Facing: 32922 51 Woven, containing asbestos yarn, tape, or cloth 32922 55 Molded, including all non-woven types 32922 00 Asbestos Friction Materials, n.s.k. Total Product Shipments, including interplant transfers (millions dollars) 1972 1967 1963 209.5 144.4 177.7 10.2 113.1 14.2 13.5 95.6 19.9 48.5 3.6 17.2 16.1 2.0 ., 3: ~ 0,a:.. ()C) cD Ul values increased by 45%, as compared to a 23% increase for the four-year period from 1963 to 1967. Using an annual figure of 9% for shipment value increases, the total product shipments of asbestos friction materials would be approxi- mately $271.3 million in 1975 and $295.7 million in 1976. Table 6.1 also gives a breakdown for the major asbestos friction --~- - - - - - < - - - -. . material products. In 1972, brake linings accounted for nearly 59% of shipment values while clutch facings accounted for slightly over 32% of the shipment ( values. If disc brake pads are included along with brake linings, then asbestos brake-materials account for 65.6% of the total value of asbestos-friction I materials. Clearly then, "brakes" are by f~r the most important commercial product in the friction material category. r 6.1.2 Industrial Firms r Table 6.2 lists the U.S. manufacturers of asbestos-bearing friction materials along with their respective sales of friction materials in I 1975. The larger firms include not only the essentially captive producers, such I as the Delco-Moraine and Inland Divisions of General Motors Corporation and the Cycleweld Division of Chrysler Corporation, but also the diversified industrial l- product manufacturers, such as Raybestos-Hanhattan, Bendix, Abex, and H.K. - Porter. In addition, the list includes many smaller, typically single-plant I firms, which man~facture friction products for both the original equipment and i. replacement market. The first eight firms listed on Table 6.2 account for nearly 15 l to 85% of the total estimated sales of asbestos friction products in 1975. This ratio is consistent with the historical pattern for the industry, which indi- i cates that in the 1954 to 1967 period, the eight largest firms accounted for l between 86 and 91% of the industry's value of shipments (Margolin and Igwe, 1975; U.S. Bureau of the Census, 1972). I 61 1 FMS\ 04896 ~--------------------------------- Table 6.2. U.S. 1-lanufacturers of Asbestos-Bearing Friction 1-laterials {Economic Information Systems, Inc., 1976; Margolin and Igwe, 1975; SRC Estimates) [ Company Plant Location Raybestos-Manhattan, Inc. Stratford, Conn. Mannheim, Pa. r Crawfordsville, Ind. Fullerton, Calif. Estimated 1975 Sales of Friction Materials {$ million) 110.0 Bendix Corporation Troy, N.Y. Cleveland, Tenn. 72.5 .Abex Corporation Cleveland, Ohio Troy, Michigan American Brakeblok Division Winchester, Va. 60.1 .General Motors Corp. Delco-Moraine Div. Dayton, Ohio Inland Division Dayton, Ohio 30.0 .H.K. Porter Co. Huntington, Indiana Richmond, Ky. 26.0 Chrysler Corporation Cycleweld Division I Trenton, Michigan Borg Warner Corporation Spring Division I. World Bestos Co. Bellwood, Ill. New Castle, Ind. 18.8 L National Friction Products Corp. Logansport, Ind. 10.2 l Gatke Corporation Carlisle Corporation I. Maremont Corporation l 1 Warsaw, Ind. Ridgeway, Pa. Grizzly Products Division Paulding, Ohio 62 10.0 9.7 8.7 FMSI 04897 Table 6.2. U.S. Manufacturers of Asbestos-Bearing Friction Materials (Cont'd) Company Plant Location Estimated 1975 Sales of Friction 1-laterials ($ million) Scandura~ Inc. Mar Pro Corporation Charlotte, N.C. Grizzly Brake Division Chicago, Ill. Standco Industries Forcee Nfg. Corporation Houston, Texas Tappahannock, Va. Royal Ind. Brake Products, Inc. l Auto Friction Corp. L. J. Niley Co. [ Friction Products Co. Danville, Ky. Lawrence, Ma. Chicago, Ill. Medina, Oh. [- United States Brake Lining Corp. Brassbestos Mfg. Corp. Niami, Fla. Patterson, N.J. Southern Friction Material Co. [ Reddaway Mfg. Co. Charlotte, N.C. Newark, N.J. Nolded Ind. Friction Corp. Prattville, Ala. [_ Auto Specialties Mfg. Co. St. Joseph, Mich. [ Lasco Brake Products Co. Oakland, Calif. California Blok Co. Gardena, Calif. I MGM Brakes, Inc. Cloverdale, Calif. Wheeling Brake Block l Mfg. Co. Wheeling, W.Va. Bridgeport, Ohio l 63 8.7 5.7 5.7 5.5 4.0 2.9 1.7 1.7 FMSI 04898 'Table 6.2. U.S. Manufacturers of Asbestos-Bearing Friction Materials (Cont'd) Company Plant Location Baldwin-Ehnet Hill, Inc. Trenton, N.J. Thiokol Chemical Corp. Trenton, N.J. P.T. Brake Lining Co. Lawrence, Mass. [ Hunt/Airheart Products, Inc. Chatsworth, Cal. Re-Bilt Auto Products Corp. Brooklyn, N.Y. [ l [ l- [ l l [ [ [ 64 [ Estimated 1975 Sales of Friction Materials ($ million) <1 <1 FMSI 04899 J I I One important discrepancy in figures should be explained. For 1972,. the U.S. Bureau of the Census listed the total value of shipments of as- l bestos friction products as $209.5 million which was projected as $271.3 million for 1975 in Section 6.1.1. From Table 6.2, the estimated sales of asbestos friction materials in 1975 total nearly $370 million for the listed figures; the companies with no listed figures may total another $50 million. The difference from the value of shipments as reported by the Bureau of the Census and the estimates given in Table 6.2 are due to variations in definition and reporting { coverage. Shipment value does not"include freight charges and excise taxes which are included in the actual sale cost. Also, the Bureau of the Census i I figures are based upon surveys at 23 asbestos-friction material establishments. J Table 6.2 contains 44 establishments. Although the Bureau of the Census survey I probably includes most of the larger establishments, the ones which were not I surveyed are not available. 6.1.3 Plants I Figure 6.1 shows the geographical dispersion of friction materials plants in the U.S. Not surprisingly, they tend to be concentrated in and around :j l the major metropolitan centers of the Northeast and Midwest, with a few plants l ! l located in California to primarily cater to the needs of the automobile assembly plants in that part of the country. l As wo.uld be expected of a mature industry, most of the plants and equipments are old, usually over forty years of age, with the possible exception i of newer captive facilities belonging to the automobile manufacturers. ProI duction processes have changed only marginally over the years, and labor rather than capital intensity appears to be the norm in most of the older plants I (Margolin and Igwe, 1975). l 65 FMSl 04900 -------------------------------------- r------ ,.----~, r r- r- (""" 0\ 0\ "T1 -3: CJ) 0 ~ Figure 6.1 Geographical Dispersion of U.S. Friction Materials Plants (Modified from Margolin and CD 0 Igwe, 1975) ..a. 6.1.4 Future Projections for Asbestos Use (Clifton, 1975) Asbestos demand for friction products was projected to the year 2000 at an 'annual growth rate of 1.50 percent. This figure was based on a formula derived from least-squares regression analysis of total asbestos demand modified by the estimated growth in the automobile industry and economic indi- caters, which showed the best correlation. Asbestos is an important part of many types of friction materials for use in automobiles, trucks, and other transportation equipment. Modern industry could scarcely function without asbestos friction materials. In addi- tion to using asbestos in brake linings, today's motor cars, equipped.with automatic transmissions, get their drive from metal transmission disks,' which are covered with a super-tough paper containing crocidolite asbestos. The average automobile with power shift contains from 8 to 12 of the paper lined disks. Although the quantity of asbestos in each transmission is small, the [ output of more than 8 million automatic transmissions annually requires disk paper production in hundreds of tons. r- t A new composition disk-brake-shoe unit containing asbestos, [ designed to meet the critical braking requirements for the new 150-mile-per-hour passenger train systems, has been developed. [ Based on an estimated forecast of the number of motor vehicles produced in the year 2000 (approximately double 1973 production) and on the l assumption that the use of asbestos per vehicle will remain at present levels, the forecast for asbestos demand in user-operated vehicles is projected to 118,000 tons. An increased number of public transportation vehicles and equip- ment using parts made of asbestos or maintaining the present quantity used per vehicle could result in a demand as high as 144,000 tons. [ 67 [ FMSI 04902 6.2 Manufacturing Process Technology ' Several different processes are used to manufacture asbestos brake linings and clutch facings. Manufacture can be accomplished by a molding proc- I ess, in a dry or wet-mixed state, or by a woven process; these processes, which are described below, are taken from Gregg (1974). The raw materials used for forming asbestos-friction materials are discussed in Section 6.3. 6.2.1 Molded Products 6.2.1.1 Dry-Mix Process The manufactur'ing steps typically used in dry-m:Lx molded brake lining manufacture are shown in Figure 6.2. The bonding agents, metallic constituents, asbestos fibers, and additives are weighed and mixed in a two- stage mixer. The mix is then hand-tamped into a metal mold. The mold is placed in a preforming press which partially cures the molded asbestos sheet. The asbestos sheet is taken from the preforming press and put in a steam preheating mold to soften the resin in the molded sheet. The molded sheet is formed to the proper arc by a steam-heated arc former, which resets the resin. The arc-formed sheets are then cut to the proper size. The lining is then baked in compression molds to retain the arc shape and convert the resin to a thermoset or permanent condition. The 1ining is then finished and, after inspection, is packaged. The finishing steps include sanding and grinding of both sides to correct the thick- l ness, edge grinding, and drilling of holes for rivets. Following drilling, the ( lining is vacuum-cleaned, inspected, branded, and packaged (Gregg, 1974). 6.2.1.2 Wet-Mix Process !I Figure 6.3 shows the major steps in the manufacture of wet- I mixed molded brake linings. The name "wet mix" process is a misnomer and refers [ It 68 FMSI 04903 ' ----------------------------------------------------- I ( I II.j I ( 1 RAW MATERIALS STORAGE PROPORTIONING PREFORMING PRESS COOLING WATER ~..._'-......,,_lllill~COOLING WATER ~~~~--~CONDENSATE COOLING WATER STEAM ~~~~~-------, p.~~L----.. .COOLING WATER ~--~~-----a~ CONDENSATE COMPRESSION MOLD BAKING OVEN +ousT INSPECTION PACKAGING STORAGE CONSUMER Figure 6.2. Dry-Mixed Brake Lining Manufacturing Operations (Gregg, 1974) 69 fMS\ 04904 r r I to the use of a solvent. The ingredients of the molded lining are actually I relatively dry. After weighing, they are mixed in a sigma blade mixer. The mixed ingredients are then sent to grinding screens where the particle size of r the mixture is corrected. The mixture is conveyed to a hopper and is forced from the hopper into the nip of two form rollers which compress the mixture into ( a continuous strip of friction material. The strip is cut into the proper ( lengths and then arc-formed on a round press bar. The cutting and arc forming operations are done by separate units. The linings are then placed in racks and [ either air-dried or oven-dried to remove the solvent. An alternative process is to place the arc-formed linings in metal molds for baking in an oven. From the I ovens, the linings are finished, inspected, and packaged (Gregg~ 1974). r Molded clutch facings are produced in a manner similar to the wet-mixed process. The rubber friction compound, solvent, and asbestos r fibers are introduced into a mixer churn. After the churn mixes the ingredients, the mixture is conveyed to a sheeter mill which forms a sheet or slab of [ the materials. The sheet is then diced into small pieces by a rotary cutter. I The pieces are placed in an extrusion machine which forms sheets of the diced material. The sheets are cut into the proper size and then punch-pressed into ( doughnut-shaped sheets. The scraps from the punch press are returned to the extrusion machine. The punched sheets are placed on racks and sent to a drying [ oven and then a baking oven for final curing and solvent evaporation. The oven[ dried sheets are finally sent to the finishing operations. Figure 6.4 illu- strates the steps in the manufacture of molded clutch facings (Gregg, 1974). ( 6.2.2 Woven Products Woven clutch facings and brake linings are manufactured of high [ strength asbestos fabric that is frequently reinforced with wire. The fabric is l 70 FMSI04905 RAW MATERIALS STORAGE PROPORnONM3 GRINDING SCREENS TWo-ROLL FOfMHG r l [ [- ~ OUST f INSPECTION [ PACKAGING STORAGE l CONSUMER l Figure 6.3. Wet-Mixed Molded Brake Lining Manufacturing Operations (Gregg, 1974) l 71 [ FMSI 04906 j I ~( RAW MATERIALS STORAGE I PROPORTIONING I COOLING WATER I ( COOLING WATER CONDENSATE --. ------~--~~ I I I I CRECYCLEO SCUDS I I I ( I ea.J ( SOLV:NT r-... SOLVENT I l l INSPECTION PACKAGING [ STORAGE CONSUt.ER I Figure 6.4. Molded Clutch Facings Manufacturing Operations (Gregg, 1974) l 72 l FMSI 04907 predried in an oven or by an autoclave to prepare it to be impregnated with resin. The fabric can be impregnated with resin by several techniques: 1) immersion in a bath of resin, 2) introducing the binder in an autoclave under pressure, ( 3) introducing dry impregnating material into carded fiber before producing yarn, and 4) imparting binder into the fabric from the surface of a roll. After the solvents are evaporated from the fabric, it is made into brake linings or ] clutch facings. Brake linings are made by calendering or hot pressing the fabric in molds. The linings are then cut, rough ground, placed in molds, and placed in a baking oven for final curing. Following curing, the lining is finished, inspected, and packaged (Gregg, 1974). I Figure 6.5 illustrates the manufacture of woven clutch facings. The treated fabric is cut into tape-width strips by a slitting machine. The strips are wound around a mandrel to form a roll of the fabric. The roll is pressed in a steam-heated press and then baked in an oven to cure the resin in the clutch facing. Following curing, the clutch facing is finished, inspected, and packaged (Gregg, 1974). 6.3 Composition of Friction Materials Many raw materials, including some whose exact roles are regarded as I proprietary knowledge, are used in varying quantities in the manufacture of ! friction materials. The major, or foundation constituent, of practically all organic friction materials is asbestos fiber. The asbestos usually used in friction materials is chrysotile from Quebec or Vermont (Jacko and DuCharme, 1973); grades 3-7 are used; however, grades 5 and 7 account for nearly 83% of the total (Clifton, 1975). Asbestos is used because of its thermal stability, relatively high friction level, and reinforcing properties. 73 FMSI 04908 l ( TREATED FABRIC I [ [ [ COOLING WATER [ COOliNG WATER CON>ENSATE ( BAKING OVEN [ -lllllll+ OUST [ INSPECTION PACKAGING STORAGE [ CONSUMER r l Figure 6.5. Woven Clutch Facings Manufacturing Operations (Gregg, 1974) r i' ~ 'l_ 74 FMSl 04909 Asbestos alone does not offer all of the desired friction properties. Therefore, other materials, known as property modifiers, are added to the asbestos fibers. Modifiers are varied in type and content to provide aesired leve~s of effectiveness, wear, fade, recovery, and noise. A binder is also added to hold the other materials together with adequate strength. 6.3.1 Binders Table 6.3 lists binders and property modifiers which are used in automotive brake linings. The binders used in the automotive industry today are primarily phenolic-type resins which are noted for high binding efficiency and ability to withstand pyrolytic breakdown (Rohl et al., 1976). They are prepared as the condensation product between the appropriate phenol (sometimes modified) I and formaldehyde in the presence of an acidic catalyst to yield the novolak. When mixed with an appropriate curing agent, they polymerize at elevated tem- l peratures to an insoluble, infusible mass (Jacko and DuCharme, 1973). Other resin systems in wide use are based on elastomers, drying oils, or combinations. I 6. 3. 2 Property Modifiers I Perhaps the widest range of materials used in friction products are the property modifiers. Table 6.3 indicates the range and diversity of i these modifiers. In general, property modifiers can be divided into two classes: non-abrasive modifiers and abrasive modifiers (Jacko and DuCharme, 1973). I 6.3.2.1 Non-Abrasive Modifiers I Non-abrasive friction modifiers can be classified further as low friction and high friction. The most common and best known of the high I friction materials is known as friction dust. This is a cured resinous material. The most frequently used variety is derived from cured or polymerized [ 75 I FMSI 04910 Table 6.3. Binders and Property Modifiers In Automotive Brake Linings (Rohl et al., 1976; Jacko and DuCharme, 1973; various patent lit-~rature; Bark et al., 1975) Binders ~Phenolic-type resins Natural rubber Buna N rubber Nitrile rubber Tire scrap Pitch Cork Gilsonite Elastomers Drying oils Property Modifiers Graphi~e Coke Coal Carbon black Gilsonite Use Function Lower friction coefficient and noise " " " II WQBRrouoaatlstrlestanzsCstt(ohoSninpii0este2)(S(Ci0a2S)i03) Zinc and compounds Alluminum Remove decomposition deposits " II II n " Limestone Clays (Caco3) Improve wear resistance II Silicas [ Barite II II r Lead and compounds Friction dusts Lubricant to prevent grabbing See discussion in Section 6.3.2.1 Antimony comp~unds Not available Calcium compounds II Copper and compounds II Barium hydroxide II [ Potassium dichromate II Magnesium carbonate " Iron oxide " [ Cryolite Fluorspar (Na6AIF3) II II Cardolite II [ Nickel Naptha II II Sulfur II Methylethyl ketone II l. Molybdenum disulfide Lubricant Calcium fluoride Lubricant L ( 76 L FMSt 04911 --~---- ~----------------------------------------------,-- cashew-nut-shell liquid, chemically a phenolic compound. When heated with hardening agents, such as hexamethylenetetramine or formaldehyde, it becomes sufficiently hard or polymerized to be granulated. Many other cured resinous or polymeric materials, some with fillers, are also used. Certain friction dusts are combinations of these materials and cashew resin. Ground rubber is normally used in particle sizes similar to, or slightly coarser than, those of the cashew [ friction dusts for noise, wear, and abrasion control (Jacko and DuCharme, 1973). Carbon black, graphite, petroleum coke flour, or other carbonaceous materials may also be added as friction modifiers to lower the friction coefficient or to reduce noise. These materials are normally used in I the form of fine powders or particles, although graphite is sometimes used in I coarse particles or pellets. The amount of friction modifier added is dependent upon the properties desired in the final composite (Jacko and DuCharme, 1973). r 6.3.2.2 Abrasive Modifiers Abrasive modifiers, such as alumina and the silicas, are I usually used in relatively small amounts and only in very fine particle sizes I (generally 100 mesh or finer). Particle size is limited by the fact that large particles of such hard materials would groove and wear the mating surfaces. l Minerals are generally added to improve wear resistance at minimum cost. Those most commonly used are ground limestone (whiting) and barytes (barium sulphate), l though various types of clay, finely divided silicas, and other inexpensive or abundant inorganic powders may also perform this function. Such materials are 'I inorganic in nature and tend to detract from noise properties and mating surface l compatibility (Jacko and DuCharme, 1973). Metals or metal oxides may also be added to perform specific l functions. Brass chips are frequently found in heavy-duty friction materials I 77 FMSI 04912 where, as scavengers, they break up undesirable surface films. Zinc and aluminum are also used. Zinc chips, in relatively small amounts, can contribute significantly to recovery of normal performance following fade (Jacko and DuCharme, 1973). 6.3.3 Composition The average composition of a typical automobile and truck brake lining ~s shown in Table 6.4a. Individual mixes may vary considerably from these averages. Table 6.4a. Average Brake Lining Composition (Lunch, 1968) Ingredient Asbestos Resins and Polymers Oxides and Pigments Metals Carbon, Graphite, etc. Automobile 55 28 9 3 5 100% Truck 33 48 16 2 1 100% Manufacturers are very reluctant to release their exact compositions due to proprietary considerations. A search of patent literature reveals limited information, although several examples from the patent literature are given in Table 6.4b. 6.3.4 Summary The tables and examples given in Section 6.3 have been included to illustrate the wide variety of compositions which are possible for fabrication of automotive and truck brake linings. Brake linings have been singled out 78 FMSI 04913 ------------------------------------------------- Table 6.4b. Brake Lining Compositions from Patent Literature Example No. 1* Asbestos Barite Phenolic resin binder Brass Magnesium carbonate Limestone Organic calcium powder 55 10 20 5 8 8 10 Example No. 2** Asbestos Phenolic resin Nitrile rubber Cashew dusts Calcium fluoride Copper iodide 60 15 3 ' 12 7 3 ~ Example No. 3*** Asbestos Barite Graphite Brass Phenolic resin Lead oxide Buna N rubber Naphtha Copper .sulfide Methyl ethyL ketone 35 2.5 7 13 7 11.5 8 7 12.5 4 Example No. 4**** Asbestos Tarry residue Barite Phenolic resin Graphite * Sakata et al., 1974 (Hitachi) ***** Toyota Central Research Keller, 1969 (Abex) and Development Labs, 1971 **** Mitchell, 1974 (duPont) 50 12 20 20 2 79 FMSl 04914 from the asbestos-friction products for examination because of their dominance of the asbestos-friction products market as shown in Table 6.1. When the varia- tions of compositions are coupled with the variations of manufacturing process methods (as described in Section 6.2), it is possible to view a brake lining made by company A as substantially different from a brake lining made by com- [ pany B, although the intended use applications may be the same. From this [ standpoint, it is entirely reasonable to speculate that asbestos emissions during automotive brake use may vary in concentration., depending upon composi- tion and process manufacture of the individual linings. 6.4 Asbestos Emissions from Brake Lining Use I Asbestos has been identified in over 200 air samples taken from the ( atmosphere of 49 cities in the United States (Nicholson et al., 1973); asbestos was present in every sample taken. Asbestos has also been found in air samples I from European cities (Holt and Young, 1973) and from air samples collected in Australia (Alste ~ al., 1976). The asbestos manufacturing industry may not be I the source of the asbestos emissions found in urban air samples cited above. I According to Holt and Young (1973), "the object of our investigations was only to determine whether asbestos fibres are present in the atmosphere of towns I where t;here is no asbestos industry. The result was positive in every case." The source of asbestos emissions, in the absence of asbestos mining and industry, is a matter of speculation. Holt and Young (1973) and I Selikoff et al. (19~2) suggest that the asbestos source may be construction which uses building materials made from asbestos. Alste et al. (1976) consider, I as a source, that asbestos emitted from automobile brake linings is a "strong possibility." Alste et al. (1976) found that the air concentration of asbestos I 80 l FMS\ 04915 was much higher at points where considerable braking occurred, as compared to points of virtually no braking. This result is apparently in agreement with measurements made in New York City which found that the asbestos air concen- trations contiguous to a toll booth were three to five times higher than back- ground levels (Anderson et al., 1973; Nicholson et al., 1971). This subsectio~ I will consider the possibility of asbestos emissions from brake lining' use. [ 6.4.1 Published Literature A number of articles and publications (Alste et al., 1976; Il Rohl et al., 1976; Jacko and DuCharme, 1973; Jacko et al., 1973; Bush et al., 1972; Hatch, 1970; Hickish and Knight, 1970; Lynch, 1968) have discussed the I asbestos emissions from the use of brake linings. Table 6.5 gives a brief summary of this published data in terms of methodologies and results. As can be seen from Table 6.5, there are important discr~pancies in the results obtained. l 6.4.1.1 Discrepancies in Asbestos Content of Emissions or Debris Lynch (1968), Hatch (1970), Hickish and Knight (1970), and Jacko and DuCharme (1973) reported figures in the range of 1% or less for the l asbestos content of emissions or debris resulting from brake lining use. Bush et al. (1972) and Rohl et al. (1976) arrived at figures which are substan- I tially higher, 44% and 2-15% asbestos content, respectively. While Alste et al. (1976) did not arrive at a percent figure, they did conclude that the major l effect of braking appears to be separation of bunches of fibres and reduction of 1 their average length, but not alteration of their crystal structure. This conclusion may certainly result in a relatively high asbestos content for wear l debris. I 81 1 FMSI 04916 ,..... c~-"'''"'""'"""'N'"..,.V~ - ........ ~ r-- ~ ,._... I ,..._,_ ~ _...~ ~~-"" ,.....~...". ........., - - - ...,..,..-. ............... - . ...- "-'~- ---------~--~.-...""""'"-~- ~ , Table 6.5. Summary of Published Data - Asbestos Emissions from Brake Lining Use Publication Source Method Used to Collect Emission or Debris Samples Hethod Used to Deter~~~ine Asbestos Content of Emission Debris Samples Asbestos Particle Size Distribution Asbestos Content of Emission or Debri~ Lynch, 1968 Laboratory simulations utilizing brake-testing machines or dynamometers. Samples collected on 0.8 ~ pore size membrane filters. Electron micrographs !lot discussed <1%, except under severe-stress conditions Hatch, 1970 A dust cloud was generated by using compressed air jets to re1110ve dust fro11 brak.e linings in an auto repair garage. Samples were collected by means of a hand pump located in center of dust cloud, .!!!1.!. stated 94% of fibers fell in 2-s ~m length category. Only 6% were longer than 5 ~~~. "'1% Hickish and Knight, Samples were collected directly from debris .!!!1.!. stated Hot discussed 1. 6% and leas co 1970 N remaining as brake dust and from membrane filters exposed during brake cleaning operations utilizing compressed air. Filter pore size i~ not given. Bush .!U_ !!., 1972 Laboratory simulations utilizing a disc brake assembly mounted on all i11ertial dynamometer. Samples were collected on suitable filtor paper. Neutron activution Hot discussed ~4% (this figure is not accurate; see discussion in Section 6.4.1.1) Jacko and DuChar111e, 1973 (contains same data as Jacko .!U_ al., 1973) Samrl~>s W~>re generated by operating n standard Aml!rlcan car on a dynamometer simulating driving conditions. Brake and clutch assembliea were enclosed by specially designed collectors. Samples wO!re collected from 1) dropouts durina usu, 2) dust retnined in lining assemblies, and 3) airborne samples collected on membrane filters. Optical and electron microscopy 30% of fibers were from o.2s-o.so ~~~ in length; 60% were longer than 0,5 ~m. 0.23% overall average (an independent chO!ck done by Batelle Labs gave a figure of 0.171%) "T1 3: ~ 0 ~ ~..... - - - -I ........... ........ ,._.. ,__ ,....... ,_. ,.._..... j (X) w Table 6.5. Summ~ry of Published Data -Asbestos Emissions from Brake Lining Use (Cont'q) Publica tlon Source Kohl !. .!!_. 0 1976 Alate !!. .!!, 1976 He tbod Used to Col lee t Emission or Debris Samples Ten samples o{ automobile brake drum dusts were collected from maintcnanc" shops in the New York o.rea. M<!thud Used to nc.'tcrmlnc AHbmt LOtt Content of EmlsHion Debris Samples x-ray diffractometry Tranwmission electron microscopy, selected area. electron diffraction, and electron microprobe analyses Samples "'ere taken from fresh and worn brake linings and from the atmosphere near a freeway. Electron microscopy and electron diffraction Attlwut uH Particle Size Distribution 80% of fibers were shorter than 0.4 ~m length, Haj ority were <2 ~ in maximum linear dimension, Asbestos Content uf Emission or Debris 2-15%; average of 3-b% Consistent with, but lower than, quantitative determination made by x-ray diffractometry; no percentages are given No percent figure given; however, conclusion "'as that major effect of braking appears to be in separating bunches of fibres and reducing their average length, but not in altering their crystal structure ., s: !!! 0 ~ ~ 01) I I I. The 44% figure computed by Bush et al. (1972) isbased upon l a neutron activation analysis, which is a technique for finding the elemental composition of a sample by irradiating the sample with neutrons, thereby causing I the elements to become radioactive. Bush et al. is careful to point out that chrysotile asbestos is a magnesium silicate and neither magnesium or silicon are I able to be determined utilizing the particular technique. Therefore, asbestos I content of the wear debris was determined by means of a scandium concentration. Scandium was a trace element <~ 4 ppm) present in the chrysotile used in the I experiment. Neutron activation can be a very precise and usefwl technique for determining elemental composition; unfortunately, the asbestos content of any J particular wear debris sample cannot be computed by an elemental analysis. I Chrysotile asbestos is a unique crystal structure of a magnesium silicate (see Section 2.1); heat or other physical means can destroy this unique structure, I thereby creating a different compound with different properties. However, the elemental composition of the different compound will be identical with chryso- I tile. Both Rohl et al. (1976) and Jacko and DuCharme (1973) determined that the I magnesium:silicon ratio of an asbestos friction material is the same before use and after use (as determined from wear debris via chemical analyses). There- I fore, the 44% asbestos content figure computed by Bush et al. (1972) does not represent the asbestos content, but rather it represents the magnesium silicate I content. When considering wear debris from friction materials, neither neutron I activation nor chemical analyses are useable techniques fpr analysis of asbestos concentration. I The major conflict to be resolved is the high asbestos content suggested by Alste (1976) coupled with the 2-15% asbestos content figure I 84 I FMSI 04919 1 obtained by Rohl et al. (1976) versus the 1% and less figures obtained by the remaining publication sources listed in Table 6.5. The difference of results ~ppears to be based upon collection methodologies, analysis techniques, and l interpretations. 6.4.1.2 Collection Methodologies and Particle Size Distribution The first major consideration of methodology is the type of samples which were collected; that is, samples produced by laboratory simulations versus samples produced during actual, real-life use. Jacko and DuCharme . (1973) and Lynch (1968) collected laboratory samples produced by simulations while Alste et al. (1976), Rohl et al. (1976), Hatch (1970), and Hickish and Knight (1970) collected real-life samples. There may be an open debate as to which collection method produces the best final results. Laboratory simulations, as conducted by Jacko and DuCharme (1973), allow entire brake assemblies to be enclosed, and therefore, all conditions could be monitored or controlled and all emissions can be collected. On the other hand, samples collected from real-life use are not only relevant, but they may provide the truest indication as to the asbestos emitted from brake lining use. Conditions encountered during actual use may not be totally reproducible in the laboratory; hence, the ashestos emission factors may be significantly different. Another area of consideration is the asbestos particle size distribution in the wear debris. Rohl et al. (1976) determined that approximately four-fifths of the wear debris fibers are shorter than 0.4 ~m in length while Jacko and DuCharme (1973) found that 30% of the fibers were from 0.25-0.50 ~m in length. According to Rohl et al., some of the discrepancies between their data and those of Jacko and DuCharme may be attributed to Jacko and DuCharme's 85 FMSI 04920 [ } r use of lower magnification (22,000X vs. 42,000X), at which fibers shorter than l 0.20 ~m may not be easily seen or identified on the electron microscopic screen. Hatch (1970) also produced size distribution figures, finding that 94% of the 1 fibers fell in a 2-5 ~m length range; however, there is no indication that Hatch attempted to look for fibers shorter than 2 ~m. Alste et al. (1976) found that I the majority of particles, which consisted of small bundles of fibers, had a l maximum dimension ot ~ 2 ~m. The best available data (Rohl et al., 1976; Jacko and l DuCharme, 1973; Alste et al., 1976) indicates that a very high percentage of the asbestos present in brake lining wear debris is shorter in length than 2 ~. 1 with a substantial portion shorter than 0.5 ~m. 1 6.4.1.3 Analysis Techniques Hickish and Knight (1970) fail to discuss analysis techniques l used to determine the asbestos content in their wear debris and, also, do not fully describe collection methods. Under these circumstances, it is difficult l to accept their results at face values. Hatch (1970) is deficient in analysis 1 methodology also, although it appears that he used electron microscopy in sizing particles down to 2 ~m. Since the Rohl et al. (1976), Jacko and DuCharme (1973), i and Alste et al. (1976) studies are the best studies yet conducted on brake lining asbestos emissions, a closer examination of the three is warranted. l As seen from Table 6.5, Rohl et al. determined their 2-15% asbestos content from X-ray diffractometry (both continuous and step-scan modes I were used). According to Jacko and DuCharme, "asbestos is readily identified 1 ,when alone or in simple mixtures at high concentrations by the following analytical methods: X-ray diffraction, thermal methods, microscopy, and infrared I 86 I FMSI 04921 analysis. However, in complex mixtures, or at very low concentrations, the analysis for asbestos is very difficult. In brake wear debris, the problem is compounded because the reaction products of asbestos, fosterite and olivine, have similar elemental ratios and similar X-ray diffraction patterns. The only sensitive method which can be used is microscopy." This conclusion by Jacko and buCharme is apparently based upo~ the assumption that samples that they were r going to produce would contain 1% or less asbestos; an accompanying table estiI l mated the asbestos content of wear debris to be less < 1%. Apparently they did not use X-ray diffraction becausethey assumed the asbestos concentr~tion would be too low. In the percent range reported by Rohl et al., namely 2-15%, X-ray diffraction is very likely an appropriate technique for quantitative chrysotile determination. Two published reports (Goodhead and Martindale, 1969; Crable, 1 1966) of X-ray diffraction techniques for determination of asbestos in dusts [ support the contention that chrysotile can be quantified with good accuracy in the percent ranges reported by Rohl et al. ( Rohl et al. further verified chrysotile presence by i transmission electron microscopy and selected area electron diffraction. "Chrysotile was found, both in fiber and fibril form, with unaltered structure ( and chemical composition. Its frequency of occurrence was consistent with, but lower than, the quantitative determination made by X-ray diffraction analysis. [ However, it should be noted that X-ray diffraction analysis is based on both I free fibers and fibers present in clumps; the latter would obscure the presence of discreet fibers on electron microscopy study." I Alate ~ al. (1976) determined the presence of chrysotile asbestos by electron microscopy and electron diffraction and concluded that the I 87 l FN'SI04922  major effect of braking appears to be in separating bunches of fibers and reducing their average length but not in altering their crystal structure. This is an important result in terms of the following consideration: If only 15%, or .~downwards to less than 1%, of wear debris is asbestos, what happens to the major portions of the asbestos originally present in the brake lining? Lynch (1968), Hatch (1970), and Hickish and Knight (1970) present a prevalent theory that "hot ..,.spots" created during braking cause the local asb-estos fibers to undergo thermal deg!adation which results in thermal metamorphosis of the asbestos into a different mineral, such as fosterite(olivine). Jacko and DuCharme (1Q73) assumed that 20-40% of the wear debris composition would be olivine. However, according to Alste ~ al. (1976) concerning wear debris from brake linings, "there was no indication from the diffraction pattern of the presence of fosterite;" this result was in agreement with Rohl et al. (1976) who also could not verify the [ presence of fosterite. Rohl et al. (1976) and Jacko and DuCharme (1973) dis- cussed other forms of brake lining wear, in addition to thermal wear, such as [ abrasive wear and macroshear wear. However, the end result is probably this: [ the asbestos present in the original brake lining, excluding the asbestos which is emitted in the wear debris, is converted by thermal or other physical proc- l ess.es in.to magnesium silicates or other recrystallized magnesium silicate structures different from asbestos. In addition to unaltered chrysotile fiber l in the wear debris, Rohl et al. (1976) observed partially altered and completely [ recrystallized fibers. Holt and Young (1973) reported. that some of the asbestos fibrils collected in European city air appeared to have been heated. 6.4.1.4 Other Considerations The Rohl et al. (1976) study is based upon a wider and more [ random sampling than that of Jacko and DuCharme (1973). Rohl et al, selected l. 88 FMSI 04923 wear debris samples from ten random automobiles undergoing brake maintenance while Jacko and DuCharme's wear debris samples came only from original auto equipment, a partial relining, and a relining for the car tested on the dynamometer. Alste et al. (1976} also collected random samples of wear debris from an auto repair shop, but apparently from only a few cars at most (a much smaller sampling than Rohl et al.}. Neither Rohl et al. (1976), Jacko and DuCharme (1973}, nor Alste et al. (1976) considered, or tested, brake linings manufactured by different companies, different techn~cal processes, or different compos~tions in any systematic manner which would be representative of the entire brake lining industry. Hence, there has been no experimental study conducted which can confirm or refute the supposition that brake linings made by different companies, processes, and compositions may contribute varying amounts of asbestos emissions into the environment. 6.4.2 Emission Quantities Table 6.6 gives the estimated annual asbestos emissions for vehicles as computed by Jacko and DuCharme (1973). These figures are based, in part, upon Jacko and DuCharme's figure of less than 1% (~0.2%} asbestos content of emission debris. They also made the following estimations: (1} The total amount of asbestos contained in all of the automotive brake friction materials sold each year is about 103 million pounds which corresponds to ~118 million pounds prior to grinding and drilling. (2} The total amount of asbestos contained in all automotive clutch friction materials sold each year is about 4.5 million pounds. 89 FMSl 04924 ___ ............ -,........,.....~ ~ I ,.._.... ~ ..........,. ,.._.. ,......, -... -.... ~-, Table 6.6. Estimated Asbestos Emissions* by Jacko and DuCharme (1973) from Vehicles \,() 0 "T1 3: ~ 0 ~ N U1 Passenger Cars Light Trucks Medium Trucks and Buses Heavy Trucks Miscellaneous (motorcycles, trailers, etc.) Totals Percent of Total Total Number of . Annual Asbestos Vehicles Emissions (lb) 96,400,000 60,400 Distribution of Total (lb) Drop-Out - 49,470 Airborne 2,230 Retention 8,700 17,100,000 32,300 28,420 940 2,940 2,600,000 16,300 14,330 470 1,500 1,200,000 6,615,000 32,900 16,300 28,920 14,330 950 470 3,030 1,500 158,200 135,470 85.6 5,060 3.2 17,670 11.2 * Includes both brake linings and clutches (3) The combined total of brake and clutch friction material worn away annually is 123.6 million pounds (117 (brakes) + 66 (clutches) = 123.6). Assuming an average asbestos content of 60%, the amount of asbestos ~orn away as friction material wear debris is ~74 million pounds. Based upon available data from other sources (Clifton, 1975; U.S. Bureau of the Census, 1972, 1975), the estimations made above ar.~ quite reasonable and are probably good figures to use in emission computations. l Table 6.7 lists the estimated asbestos emissions using the Rohl et al. (1976) figure for the asbestos content of wear debris. Computations l were made using the same assumptions and method as Jacko and DuCharme (1973); the only variation is the use of different asbestos content percentages. i Rohl et al. (1976) arrived at an average asbestos content figure of 3-6% (therel fore, a median of 4. 5% is listed in Table 6. 7) and high-low values of 2-15%. A comparison of Table 6.6 and 6,7 reveals that the total annual 1 asbestos emissions reported in Table 6.7 (4.4% median) is nearly 22 times higher than the total reported in Table 6.6. The focal point of the difference is the I percentage of asbestos which survives in the wear debris. I Jacko and DuCharme (1973) determined that approximately 3% of the asbestos emission become airborne. Based upon sample concentrations collected at freeway exits, Alste et al. (1976) concluded that only a small fraction of the total dust formed becomes airborne, which is consistent with Jacko and DuCharme. l 6~4.3 Human Exposure to Asbestos Emissions During Brake Lining Maintenance and Repair In the United States, an estimated work force of at least 900,000 auto mechanics and garage workers is potentially exposed to asbestos in I 91 I FMSI 04926 I .............~..-- ~ ~. ~Pi'.... ~ ~ ,__ --. ..----, I I Table 6.7. Estimated Asbestos ~missions from Vehicles Using Rohl et al. (1976) Figures for Asbestos Content of Wear Debris ---- Asbestos Content . of Wear Debris Total Annual Asbestos Emissions (lb) Distribution of Total (lb) Drop-Out Airborne Retention 2% (low) 1,520,000 1,300,000 49,000 171,000 \0 15% (high) 11,400,000 9,800,000 360,000 1,280,000 N 4.5% (median 3,420,000 2,930,000 110,000 380,000 of average 3-6%) "T1 3: !!! 0 ~ CD ~ the servic~ng of both brake and clutch linings (Rohl et al 1976). Measurable concentrations of asbestos fiber have been observed and reported in the work environment of workmen involved with brake and clutch linings maintenance and repair (Hickish and Knight. 1970; Hatch, 1970; Boillat and Lob, 1973; Rohl et al., 1976). When a vehicle is brought into a repair shop for brake lining inspection or replacement, the wheel is removed and the loose dust is removed from the drums and back plates, generally by means of a compressed air jet. A cloud of dust is produced by this air jet l<~hich is visible for several minutes. Table 6.8 lists the fiber concentrations which were measured as a result of the dust cloud by the most relevant study (Rohl et al . 1976) to American standards of exposure; also given are concentrations measured for common truck servicing operations. The result of the Rohl et al. (1976) study indicates that it is common for OSHA asbestos-fiber concentration standards to be exceeded during brake cleaning operations. It should be noted that fiber counts made during this study were in accordance with procedures adopted by OSHA. Essentially, the analysis consists of counting fibers 5 to 100 ~m using phase contrast microscopy at a magnification of 400X. Section 6.4.1.2 revealed that most of asbestos present in wear debris is much smaller than 5 pm. Rohl ~ al. (1976) estimated that 80% of the fibers present are shorter than 0.4 ~m. Accepting these results, it is obvious that the asbestos exposure during brake servicing may be a great deal higher than is indicated by OSHA test standards. 93 FMSI 04928 Table 6.8. Asbestos Concentration During Automobile and Truck Brake Service* (Rohl et al., 1976) Operation Distance (ft) Number of Samples Fiber Concentration (fibers/ml) Mean Range -A,u,-to- - Blowing dust out of brake drums with compressed air 3-5 < 5-10 10-20 4 16.0 6.6-29.8 3 3.3 2.0-4.2 2 2.6 0.4-4.8 Truck Renewing used linings by grinding 3-:-5 10 3.8 1.7-7.0 Truck - Beveling new linings 3-5 5 37.3 23.7-72.0 * Fibers 5-100 ~m in length, counted by optical microscopy. ( 6.5 Alternatives to Asbestos as a Friction Material I 6.5.1 The Role of Asbestos in Friction Linings I Originally, automotive brake linings were made from a cotton textile material which was impregnated with drying oils and cured to form a I strip of material which was flexible, conformable, and mechanically very strong. The main purpose of the drying oil was to protect the cotton from attack by [ atmospheric oxygen, which, even at the temperatures reached by early brakes, would have resulted in burned cotton had its surface been exposed to the air. I As brake operating temperatures increased, it was found that cotton started l to degrade and lose its strength even though still protected from oxygen attack. In other works, the cotton suffered thermal degradation instead of f oxidative degradation (Hatch, 1970). I 94 l FMSI 04929 Around 1910, a technological breakthrough was achieved when it was discovered that asbestos could be woven and used to replace cotton because asbestos neither burns nor loses its strength below about 500C. When braking operations became more severe, in the 1940's, brake linings began to be manu- factured by moulding powdered resins with short asbestos _fibers. This made [ possible the inclusion of various property modifiers to aid in the braking operations (Hatch, 1970). As described in Section 6.2, this is the current ( method of brake lining manufacture. I Any alternative material to asbestos in brake linings has to compete with asbestos's properties of strength, high temperature protection, t insulation, and good frictional properties. 6.5.2 Alternatives in Brake Linings 1 At this time, there are no commercially available, asbestos-free brake linings intended for use in automobiles with drum brakes (Aldrich, 1977; f_ Rosenburg, 1977). This is not the case when considering disc brake pads, as 1- will be explained later. Currently, nearly all of the major brake lining manufacturers are engaged in research and testing programs to develop asbestos- i free drum brake linings for automobiles; commercial success has not been achieved. l It should be noted that, if by "alternative" we mean a new or better fiber which might shortly be available as a replacement for asbestos in conventional brake l linings, the chances are actually quite remote. The possible asbestos alternatives which are being tested and l considered are discussed below (Hatch, 1970; Aldrich, 1977; Rosenburg. 1977): (1) Glass Fiber - overall strength is lower than that of asbestos, but strong enough for friction material applications. Unfortunately, at the temperatures l reached by braking operations, glass fiber melts, even in depth below the operating surface. i 95 FMSI 04930 --------- r l [ [ Il [ l l [ l (2) Steel Wool - compared to asbestos, the overall strength is lower and the cost is much higher. In addition, the material hardness of steel wool damages the brake drums. (3) Mineral Wools - overall strength is very low and brittle to the extent of limiting mixing processes. (4) Carbon Fiber - the main properties of carbon fibers are generally good, but still somewhat inferior to asbestos. A major consideration is the cost, which is' a great deal more. than asbestos. (5). Sintered Metals and Cermets - these materials are now being used to manufacture brake linings for railroad cars and airplanes. Eventually, these materials may be developed into practical applications for automobiles. At this time, the wear-resistance is not good enough for automotive uses ~d the cost is too high. There are two good reasons why the industry is attempting to develop asbestos-free products. First, there is the possibility of a govern- mental ban on asbestos applications which emit asbestos fibers into the atmos- phere. And secondly, asbestos-free manufacture would eliminate the need for asbestos-environmental control devices in the workplace and would eliminate a health hazard to employees, thereby eliminating a substantial expense. Some American brake lining manufacturers are currently maneuvering around the second . reason above by establishing manufacturing plants in foreign countries whose pollution regulations are much less stringent than in the United States. The friction products containing asbestos can then be imported into the U.S. 6.5.3 Alternatives in Disc Brake Pads It is purely fortuitous that thefrictiort materials used in disc brakes are designed to a stronger shape than in drum linings; that is, more or less square or circular pads of considerable thickness are supported by a metal plate of adequate thickness. Therefore, the friction material does not have to stand up to handling during assembly, does not have to withstand riveting, and 96 FMSI 04931 .could, from the point of view of bulk mechanical strength alone, be made without a high loading of fibrous reinforcement of any kind. There remains, however, thermal shrinkage and thermal shock, and in order to prevent the formation of tensile cracks normal to the operating surface, a percentage of asbestos fibre is still retained (Hatch, 1970). Nevertheless, it cannot be said that the use of asbestos in disc brake pads remains a technical necessity (Hatch, 1970); in fact, commercially available disc pads have been developed for automotive uses which do not use asbestos (Aldrich, 1977). Table &.9 lists a typical composition for ,this asbestos-free disc pad. Cost of the asbestos-free pad is somewhat higher than the asbestos pad. Table 6.9. Asbestos-Free Composition of a Disc Brake Pad (Aldrich, 1973) (vol. %) Carbon Iron Powder Steel Fiber Phenolic Resin 45 25 10 20 (manufactured by common methods) 6.5.4 Alternatives in Clutches Borg-Warner Corporation, a major manufacturer of clutches, is currently engaged in the testing of asbestos-free friction materials intended for use in clutches (Rosenburg, 1977). The asbestos-free materials being tested have been developed by the major friction-material producers such as RaybestosManhattan and Abex. To date, none of the alternatives tested have been as go~d as asbestos. 97 f~S\04932 6.6 Summary and Conclusions for Asbestos Friction Applications (1) Chrysotile asbestos fiber is a major component of brake and clutch lining friction materials. Asbestos is used because it imparts strength, ~.good friction properties, can withstand high temperatures, and is a good insula- tor. (2) The annual U.S. demand for asbestos in friction products has [ rhistorically ranged from 65-80 thousand short tons, or approximately 9% of the total U.S. asbestos demand. Projections calculated from 1972 figures released [ by the U.S. Bureau of the Census indicate that the shipment value oi all asbestos- ;friction products is currently about $300 million. [ (3) At present, nearly 118 million pounds (59 thousand short tons) of ( chrysotile asbestos are consumed annually for fabrication of automotive brake linings. I (4) Asbestos usually used in friction materials is chrysotile from Quebec and Vermont. Length grades 5 and 7 account for nearly 83% of the total [ use. (5) Approximately 35 corporations operating a total of 44 plant 1. ~establishments are currently engaged in manufacturing asbestos-friction material [ products. '(6) The eight largest corporations (headed by Raybestos-Manhattan, l Bendix Corporation, and Abex Corporation) control from 75-85% of the asbestosfriction material market. I (7) Several different process technologies are vsed to manufacture I asbestos brake linings and clutch facings. Manufacture can be accomplished by a molding process, in a dry or wet-mix state, or by a woven process. I 98 { FMS' 04933 l _ r l (8) A wide variety of ingredient compositions are used for the fabrication of automotive brake linings. In addition to the 30-60% typical asbestos content, at least 43 different inorganic and organic compounds have been listed for use by previous publications and patent literature, as property modifiers and binders. (9) It may be reasonable to speculate that asbestos emissions resulting from automotive brake lining use may vary in concentration, depending upon the ingredient composition and the process method used to manufacture the individual lining. (10) Among the studies which have examined asbestos emissions or wear debris from brake linings, the best appear to be Rohl et al. (1976), Jacko and DuCharme (1973), and Alste et al. (1976). These studies utilized different methodologies and arrived at different results. Rohl et al. (1976) examined random samples of brake lining wear debris from automobiles used under real-life conditions and determined, by X-ray diffractometry, that 2-15% of the wear debris was asbestos. Jacko and DuCharme {1973) produced samples of wear debris by means of laboratory simulation utilizing a car on a dynamometer, with specially designed collection apparatus, and concluded, by electron microscopy, that the wear debris contained, on average, only 0.2% asbestos. Using real-life samples examined by electron microscopy and electron diffraction, Alste et al. (1976) concluded that the major effect of braking appears to be in separating bunches of fibers and reducing their average length, but not in altering their crystal structure. This disparity in results, computed by"very qualified researchers, leads to the conclusion that additional work is required in determining a more consistent evaluation of asbestos in wear debris from brake linings in terms of content percentage. 99 FMSI 04934 (11) There has been no experimental study conducted which can confirm or refute the supposition that brake linings made by different companies, processes, and compositions may contribute varying amounts of asbestos emissions into the environment. This supposition is offered as a suggestion which may be ._beneficial in the explanation of the different results obtained by Rohl et al. (1976), Jacko and DuCharme (1973), and Alste et al. (1976). (12) According to Jacko and DuCharme (1973), the total asbestos contribution to the environment as a result of brake and clutch lining wear is nearly 158,000 lbs/yr, of which 5,060 lbs/yr is airborne. Utilizing the results 'Obtained by Rohl ~ al. (1976) for asbestos content of wear debris, we can calculate that the total environmental contribution, on average, would be 3,420,000 lbs/yr, of which 110,000 lbs/yr would be airborne. Obviously, the differences are significant. (13) A very high percentage of the asbestos emitted in wear debris is shorter than 5 pm in length. In fact, Rohl et al. (1976) found that nearly 80% of this asbestos is shorter than 0.4 ~m. This is an extremely important consideration when dealing with exposure to workers, such as brake service mechanics, who come into direct contact with this airborne wear debris. OSHA standards count only fibers from 5-100 ~m in length; therefore, any measurements made by OSHA st~ndards would seriously underestimate the asbestos exposure to the workers. Rohl et al. found that even under OSHA test standards, asbestos fiber concentrations would periodically exceed OSHA regulations during brake maintenance and repair. Therefore, a potentially serious asbestos exposure exists for the estimated 900,000 persons employed as auto mechanics and garage workers. 100 FMSI 04935 REFERENCES Aldrich, F.W. (1977), Personal Communication, Bendix Corp., Troy, N.Y. 1 Aldrich, F.W. (1973), Ger. Offen. 2,304,732, Aug. 9, 1973; U.S. Patent Appl. 222,342, Jan. 31, 1972, assigned to Bendix Corp. A1ste, J., Watson, D., and Bagg, J. (1976), "Airborne Asbestos in the Vicinity of a Freeway," Atmos. Environ. , ]_, 583-9. Anderson, A.E., Gea1er, R.L., McCune, R.C., and Sprys, J.W. 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(1976), "Asbestos: A Review of Selected Literature through 1973 Relating to Environmental Exposure and Health Effects," Office of Toxic [ Substances, Environmental Protection Agency, EPA Report No. EPA-560/2-76-001. 102 l FMSI 04937 Lynch, J. R. (1968), 11Brake Lining Decomposition Products, J. Air Pollut. Cont. Assoc., 18, 824-6. Margolin, S.V. and Igwe, B.U.N. (1975), "Economic Analysis of Effluent Guidelines: The Textile, Friction and Sealing Materials Segment of the Asbestos Manufacturing Industry," U.S. Nat. Tech. Inform. Service. PB-250 682. Mitchell, A. (1974), "Ger. Offen. 2,409,916, Oct. 10, 1974, assigned to E.I. duPont de Nemours. Modic, F.J. and Barsness, D.A. (1965), "Embedding," Kirk-Othmer Encycl. Chem. Technol., 2nd Ed., !, 102-16. Nicholson,.W.J., Langer, A.M., and Selikoff, I.J. (1973), "Discussion- Asbestos Fibres in the Air of Towns," Atmos. Environ. , ]_. 666-8. Nicholson, W.J., Rohl, A.N., and Ferrand, E. F. 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The Asbestos Factbook (1970), printed by Asbestos (Asbestos Magazine), Willow Grove, Pennsylvania. l. Toyota Central Research and Development Laboratories, Inc. (1971), British Patent 1,235,100, June 9, 1971. [ U.S. Bureau of the Census (1972), "1972 Census of Manufacturers," U.S. Gov't. Printing Office, Washington, D.C. 103 l FMSl 04938 ----------------------------------------- U.S. Bureau of the Census (1975 a), "U.S. General Imports," Report FT135, December, 1975, U.S. Gov't. Printing Office, Washington, D.C. U.S. Bureau of the Census (1975 b), "U.S. Exports- Schedule B Commodity by Country," Report FT410, December, 1975, U.S. Gov't. Pr~nting Office, Washington, D.C. U~S. Bureau of the Census (1976 a), "U.S. General Imports," Report Frl35, June, 1976, U.S. Gov't. Printing Office, Washington, D.C. U.S. Bureau of the Census (1976 b), "U.S. Exports- Schedule B Commodity by Country," Report Fr410, June, 1976, U.S. Gov't. Printing Office, Washington, D.C. U.S. Census of Manufacturers (1967, 1972), see U.S. Bureau of the Census (1972) l l l l { l l l l l 104 l FMSt 04939 FMSI 04940