United States
Environmental Protection
Agency
Office of Pesticides &
Toxic Substances
Washington, DC 20460
EPA-560/3-80-001
November, 1980
Toxic Substances
Proceedings of the National
Workshop on Substitutes
for Asbestos
Sponsored by:
The Environmental Protection
Agency
The Consumer  Product Safety
Commission
The Interagency Regulatory
Liaison Group

-------
                                      EPA-560/3-80-001
                                      November 1980
     PROCEEDINGS   OF  THE
   NATIONAL  WORKSHOP  ON
SUBSTITUTES  FOR  ASBESTOS
 Arlington,  VA, July 14-16, 1980
                 Sponsored by:

       United States Environmental Protection Agency
     United States Consumer Product Safety Commission
         Interagency Regulatory Liaison Group
             Arlene Levin, Co-editor
              Contract flo., ,68-02-3168
                   Task 17
      EPA Project Officer and Co-editor:  Hope Pillsbury

        Office of Pesticides and Toxic Substances
         U.S. Environmental Protection Agency
                 Prepared for

         U.S. ENVIRONMENTAL PROTECTION AGENCY
       Office of Pesticides and Toxic Substances
              Washington, D.C.  20460

-------
                              DISCLAIMER NOTICE
     Convention of the National Workshop on Substitutes for Asbestos and
publication of this document do not signify that the contents necessarily
reflect the joint or separate views and policies of each sponsoring Agency.
Mention of trade names or commercial products does not constitute endorsement
or recommendation for use.

-------
                                   PREFACE
     The purpose of the National Workshop on Substitutes for Asbestos was to
obtain more information on the technical and economic feasibility and
possible health problems of substitutes for asbestos, for use in considering
regulation of asbestos.  The Workshop was co-sponsored by the Environmental
Protection Agency (EPA), the Consumer Product Safety Commission (CPSC), and
the Interagency Regulatory Liaison Group.  It was held at the Sheraton
National Hotel in Arlington, Virginia, July 14 to 16, 1980.  It was attended
by over 600 people from industry, government, public interest groups, labor,
and other interested parties.

     Most of the technical/economic portion of the workshop consisted of talks
on substitutes for asbestos product categories, followed by question and
answer periods.  Eight roundtable discussion sessions were held concurrently
for each category of substitutes for asbestos.  An evening panel discussion
was held in which representatives from industry, government, labor, and
environmental groups discussed substitutes for asbestos.  On the second day
of the workshop, a session was held in which manufacturers and other experts
on asbestos supplied information about substitute materials and products.

     The second portion of the workshop focused on health effects of both
fibrous and nonfibrous types of substitutes.  An overview on routes of expo-
sure was presented, followed by papers on epidemiological and experimental
studies of various substances that can ^e used as substitutes for asbestos.
Discussion sessions followed the presentations.  An evening session was held
to discuss the health aspects of exposure to talc.

                                                     Chairmen

                                     Richard J. Guimond and James N. Rowe, Ph.D.
                                     Office of Pesticides and Toxic Substances
                                     U.S. Environmental Protection Agency
                                     iii

-------
                                  CONTENTS


Acknowledgments                                                          viii

Introductory Remarks, Richard J. Gulmond                                     *

Overview of Regulatory Status, Peter Preuss and Warren Muir                  3

ECONOMIC SESSIONS:  Richard J. Guimond, Chairman
    WORK SESSION ON FRICTION PRODUCTS
        Non-Asbestos Friction Materials, Michael G.  Jacko, Charles M.
          Brunhofer, and F. William Aldrich                                  9
        Discussion on Friction Products                                     32
    WORK SESSION ON GASKETS AND PACKINGS
        Gaskets and Packings, Stephen D. Koehler                            35
        Discussion on Gaskets and Packings                                  58
    WORK SESSION ON PLASTICS AND FLOORING
        Asbestos in Plastics:  Looking for Alternatives, Matthew Naitove    59
        Discussion on Plastics and Flooring                                 69
    WORK SESSION ON PAPER AND ROOFING PRODUCTS
        Single-Ply Roofing as a Substitute for Asbestos Roofing Felt,
          David E. Bailie                                                   71
        Roofing Felt, Nancy Roy                                             75
        Discussion on Roofing Products                                      82
        Mill Applied Coatings for Underground Pipelines, Jack Wink          84
        Discussion on Pipeline Wrap                                         99
    WORK SESSION ON TEXTILES
        Textiles, Samuel G. Manfer                                         101
        Discussion on Textiles                                             106
    WORK SESSION ON SEALANTS
        Asbestos Substitutes in Roof Coatings, Kenneth Brzozowski          109
        Overview of Asbestos Substitutes in Sealants, Roof Coatings, and
          Cements, Eric Wormser                                            113
        Discussion on Sealants                                             119
    WORK SESSION ON SUBSTITUTES FOR ASBESTOS-CEMENT SHEET
        Glass Fiber Reinforced Cement, John Jones and Frank W. Fekete      121
        Other Substitutes for Asbestos-Cement Sheet, David Cogley          129
        Discussion on Substitutes for Asbestos-Cement Sheet                135

-------
    WORK SESSION ON SUBSTITUTES FOR ASBESTOS-CEMENT PIPE
        Substitutes for Asbestos-Cement Pipe, Richard A. Simonds and
          James L. Warden                                                  139
        Discussion on Substitutes for Asbestos-Cement Pipe                 161

    PANEL ON DEVELOPMENT OF SUBSTITUTES
        Presentations by Richard J. Guimond, Robert Moore, John Gurtowski,
          Roy Steinforth, James F. Reis, and Barry Castleman               163
        Discussion on Development of Substitutes                           175

    ROUNDTABLE DISCUSSION SESSIONS
        Introductory Material to Roundtable Discussion Sessions            181
        Summaries of Roundtable Discussions                                194

    PRODUCT AND SUBSTITUTE MATERIAL REVIEW SESSION                         229

HEALTH SESSIONS:  James N. Rowe, Ph.D., Chairman
    Scope of the Health Workshop, James N. Rowe                            279

    OVERVIEW OF THE ROUTES OF EXPOSURE
        Inhalation, Deposition, and Clearance of Particles,
          Morton Lippmann                                                  283
        Fate of Ingested Particulates, James Millette and
          M. Rosenthal                                                     313
        Discussion on the Routes of Exposure                               323

    SYNTHETIC FIBROUS SUBSTITUTES
        Man-Man Vitreous Fibers and Health, Jon L. Konzen                  329
        Discussion on Man-Made Vitreous Fibers                             342
        The Translocation and Fate of Sized Man-Made Mineral Fibers
          Following Exposure by Intratracheal Instillation in Rats,
          David M. Bernstein, Robert T. Drew, and Marvin Kuschner          343
        Discussion on the Translocation and Fate of Sized Man-Made
          Mineral Fibers                                                   391
        Occupational Exposures to Mineral Wool, Douglas P. Fowler          395
        Discussion on Mineral Wool                                         418
        Mortality Patterns of Rock and Slag Mineral Wool Production
          Workers, Cynthia F. Robinson, Gregory 0. Ness, Richard J.
          Waxweiler, and John M. Dement                                    419
        Discussion on Rock and Slag Mineral Wool                           420
        Industrial Hygiene and Toxicology Aspects of 3M Nextel  312
          Ceramic Fibers, Robert S. Larsen and William McCormick           425
        Discussion on Ceramic Fibers                                       441
        Toxicology of Aramid Fibers, C. F. Reinhardt                       443
        Discussion on Aramid Fibers                                        448
        Environmental Exposure Considerations Due to the Release of
          Graphite Fibers During Aircraft Fires, Benjamin Sussholz         451
        Discussion on Graphite Fibers                                      474
                                     vi

-------
NATURAL FIBROUS SUBSTITUTES
    Cross-Sectional Medical Study of Wollastonite Workers,
      Brian Boehlecke, D. M. Shasby, M. R. Petersen, T. K. Hodous,
      and J. A. Merchant                                               475
    Discussion on Wollastonite                                *         476
    Endemic Pleural Disease in Relation to Zeolite Exposure,
      Arthur N. Rohl                                                   477
    Discussion on Zeolites in Turkey                                   482
    Chemical Detoxification of Asbestos Fibers, Earl S. Flowers         489
    Discussion on Chemical Detoxification of Asbestos Fibers           497
NATURAL NON-FIBROUS SUBSTITUTES
    Health Considerations in the Perlite Industry, W. Clark Cooper     505
    Discussion on Perlite                                              511
    Review of the Health Effects of Micas, Ilmar Lusis                 513
    Discussion on Mica                                                 554
    Health Effects of Venniculite, James E. Lockey and
      Stuart M. Brooks                                                 555
    Discussion on Venniculite                                          560
Talc:  Roundtable Discussion (Evening Session)
    Opening Remarks:  Natural Non-Fibrous Substitutes:  Talc,
      Arthur M. Langer                                                 563
    Cross-Sectional Epidemiologic and Industrial Hygiene Survey  of
      Talc Workers Mining Ore from Montana, Texas, and North Carolina,
      John Gamble, Alice Greife, and John Hancock                      570
    Roundtable Discussion on Talc                                      612
SYNTHETIC NON-FIBROUS SUBSTITUTES
    Occupational Exposures in the Manufacture and Application of
      Polyurethane and Urea Formaldehyde Insulation Systems,
      Robert F. Herrick, A. A. Alcarese, R. P. Reisdorf, and
      D. W. Rumsey                                                     621
    Discussion on Foams                                                644
    Human Pulmonary Function Study (5 years) on Occupational
      Isocyanate Exposure, Hans Weill                                  647
    Discussion on Isocyanate                                           652
CRITERIA FOR EVALUATING SUBSTITUTES
    Criteria for Animal, Tissue Culture, and Biochemical Studies
      on Asbestos, Mineral Dusts, and Proposed Substitutes for
      Asbestos, Earl S. Flowers                                        653
                                 vii

-------
                              ACKNOWLEDGMENTS


     We gratefully acknowledge all who aided in organizing and producing the
Workshop on Substitutes for Asbestos.  The Chairmen express special thanks
to the speakers and participants, who provided much insight and information
about the subject.

     The editing work on the Proceedings, performed by the EPA and CPSC staff
and their contractors, GCA Corporation and Merenda Associates was also very
much appreciated.
                                     viii

-------
                            INTRODUCTORY REMARKS

                                    by

                         Chairman Richard J.  Guimond
                    U.S. Environmental Protection Agency
                              Washington, D.C.


     Welcome to the first National Workshop on Substitutes for Asbestos.  I
will be chairing the technical and economic sessions of this workshop.

     We hope you find the meeting informative.   I have been looking through
the presentations and I have found much that I was not aware of before and
much that has expanded our horizons.

     There are going to be eight Roundtable discussions.  There is a list of
questions, issues, and topics that we would like to take up in those Round-
tables.  The first page of the handout for the Roundtable discussion is a
general set of questions that apply to all Roundtable discussions, but the
remaining pages focus on the individual sessions.  There is a session for
asbestos friction products, reinforced plastics, flooring, gaskets and pack-
ings, paper and roofing products, textiles, asbestos cement sheet, and asbes-
tos cement pipe.  People are free to move around the various sessions, in
case you want to learn about more than one topic or participate in more than
one session.

     Because of the large number of participants attending the meeting, I am
going to ask that all remarks or questions be held to 3 minutes, so that
everyone has an opportunity to ask a question or to make their comment.

-------
                               REGULATORY STATUS

                                      by

                              Dr.  Peter Preuss
                   U.S.  Consumer Product Safety Commission
                              Washington, D.C.

                                     and

                               Dr. Warren Muir
                    U.S. Environmental Protection Agency
                              Washington, D.C.


DR. PETER PREUSS

     We are here at this workshop  to try to learn from you about an issue that
is of a great deal of concern in many places.   Some of you may not be entirely
familiar with the Consumer Product Safety Commission (CPSC) and what we do and
how we function.  The Consumer Product Safety Commission is an independent
agency headed by five commissioners and a chairman appointed by the President.
Basically, we administer two statutes that allow us to deal with and regulate
asbestos, other hazardous materials, and health and safety issues related to
consumer products.

     Under the Consumer Product Safety Act, the Commission has the general
responsibility to protect the public from unreasonable risks of injury, illness,
or death associated with consumer  products.

     The second Act, the Federal Hazardous Substances Act, allows us to regu-
late hazards presented by the presence or use of toxic and other hazardous
substances.

     In the past, the agency has used both of these Acts in controlling sub-
stances they felt posed a hazard.   Regardless of which statute we have used
in the past or which we might use  in the future, one of the keys to effective
regulation is having not only good communication from all involved parties,
but also having regulations that are based on good and appropriate information.
This has been one of the issues that 1 have been speaking about ever since I
came to the Commission about a year ago because it has troubled me that there
has not been a sufficient flow of  information.  And whether it was at the meet-
ing of the Asbestos Information Association or a variety of other forums where
I have been privileged to represent the Commission, I have tried to make this
point:  that our regulations and our efforts are, indeed, limited by the quan-
tity and quality of the information that we have available to us at the time
that we make our decisions.
                                      3

-------
     Now, on  this  issue  specifically,  that is  the use of asbestos and asbestos
substitutes,  we have made  a number  of  attempts over the past 8 or 10 months to
try  to acquire some of the information that we felt was important and necessary.
In October  of last year, the  Commission,  together with EPA, published an
Advanced Notice of Proposed Rulemaking (ANPRM) where we, in general, outlined
our  thinking  and our approaches  to  the question.  CPSC, in particular, tried to
get  some idea of the scope of the potential problem posed by consumer products
containing  asbestos.  A  number of very specific questions were asked at that
time.

     And since then, we  have  followed  through  in the direction that ANPRM had
indicated.  Very recently, the Commission has  voted to approve a General Order
that requires the  submission  of  information about the use of asbestos in a
variety of  consumer products.  The  point  is to obtain some very specific infor-
mation for  a  number of defined and  specified consumer products.  We hope that
these kinds of efforts will provide us with the information that is important
and  necessary to make our  decisions.

     In addition,  we have  just completed  setting up a test facility in Chicago
to look at  asbestos and  other fibers as they may be emitted from consumer
products.   That laboratory is now beginning to look at many materials and prod-
ucts.  This kind of effort will  become more important and the information we
gather will become more  important as we move from asbestos to some of the
substitute  materials.

     I think  one of the  points of this workshop is that if we have learned
anything from our  past efforts,  it  really is very important to try to accumulate
the  information and assess and evaluate the information before we go too far
down any one  road.  We cannot wait  until  materials are in widespread use, until
everybody is  exposed, or until they are present in all parts of the environment
before we begin to look  at deleterious health  effects.

     So we  are looking forward,  during these 3 days, as a regulatory agency, to
obtaining some of  the information dealing with the identity, the uses, and the
possible adverse health  effects  from consumer  exposure to this potentially very
large group of materials that we are,  for convenience, calling "asbestos
substitutes."

     I want to point out that this  workshop, although the headings indicate
"EPA/CPSC," is more than just an effort of these two agencies.  It is, indeed,
an effort that is  being  coordinated by all of  the agencies belonging to the
IRLG,  the  Interagency Regulatory Liaison Group, which is composed of five
agencies.   In addition to  the EPA and  CPSC, there is the Food and Drug Admin-
istration,  the Occupational Safety  and Health  Association, and the Food Safety
and  Quality Service of the Department  of  Agriculture.  I mention this because
these IRLG  agencies have been working  very hard over the past year on this
topic of asbestos  and asbestos substitutes to  try to make sure that we are
sharing information; that  we  are not stepping  on each other's toes', that we
are not duplicating efforts;  that we make sure what we are doing is as coherent
and as reasonable  as we can possibly make it so that this workshop and the
information that comes from it will clearly be shared with all of those
agencies.

-------
     Again, these agencies, the IRLG agencies, have been looking for ways to
foster communication and to try to be a little bit more innovative than in the
past.  Hopefully, this workshop will serve as a model for that effort, and so,
after the 3 days are over, we will all agree that we have benefited from this
exercise.  We will have benefited particularly by learning a great deal from
you; by learning a little better what our needs are; and jointly, by under-
standing how we can communicate a little bit better with each other.

     The workshop is structured in a way to allow maximum participation by all
of the people who are attending.  And to get those of you who, clearly, know
much more about many of these specific areas to participate with us and to try
to share knowledge.  The sessions will cover a variety of topics, everything
from physical uses to health effects.  I think you all have an obligation to,
in fact, participate with us in these efforts so that we can make this work-
shop a success.  And, again, I think that the more informed we are, as
regulatory agencies, as we proceed in our regulatory investigations, the better
our chances are of obtaining the best results.

DR. WARREN MUIR

     We in the Office of Pesticides and Toxic Substances are currently con-
ducting a rulemaking investigation on the commercial and industrial uses of
asbestos.  We are holding this conference as part of our investigation in an
effort to expand our knowledge regarding the substitutes of asbestos.  We want
to learn as much as possible about asbestos substitutes in various product
categories.  We are eager to learn about their performance, their cost, and
any health and environmental risks that they may pose.  This rulemaking pro-
ceeding is being conducted under the Toxic Substances Control Act, more often
referred to as TSCA.  The Act required that EPA eliminate unreasonable risks
of human and environmental injury posed by chemical substances.

     Several factors are involved in evaluating whether or not asbestos, or any
chemical substance or mixture, presents an unreasonable risk.  To promulgate
a rule to control risks from exposure to asbestos, the EPA plans to consider
the following three things and, indeed, such factors would weigh into any
control regulation under the Toxic Substances Control Act.

     The first of these is the hazard of asbestos on health and the magnitude
of exposure to humans.  Secondly, the benefits of asbestos from its various
uses and the availability of substitutes.  And thirdly, the reasonableness of
the ascertainable economic and regulatory impact of any rulemaking that we
would undertake.  These three factors would enter into, generally, any regu-
latory action that we would take.

     EPA's preliminary health assessment, which we have been undertaking, indi-
cates that asbestos poses a substantial risk to human health.  The various
toxicological characteristics of asbestos have been well known for many years
and our assessment has, in essence, confirmed those relatively well  known
characteristics.

-------
      This conclusion has prompted our initiation of the rulemaking proceeding.
 In deciding on the specifics of such a rule, we felt it appropriate to investi-
 gate the substitutes of asbestos; and, hence, we are interested in participating
 with the Consumer Product Safety Commission in undertaking this workshop.  We
 wanted to make sure that we had made a careful examination of the availability
 of reasonable substitutes for the various uses of asbestos and, therefore, we
 are investigating both those substitutes already available commercially and
 those anticipated to be available in the near future.

      EPA wants to know about the good and bad characteristics of the substi-
 tutes so that our decisions will reflect the best information available.  This
 workshop is one of our efforts aimed at gathering and evaluating such informa-
 tion.  As Dr. Preuss has pointed out, our ability to undertake these actions,
 in any reasonable fashion, is really predicated upon a good information phase.

      Other information collection actions include contractor studies and com-
 ments on an Advanced Notice of Proposed Rulemaking that we had in the Federal
 Register.  Under our current schedule, we expect to complete our deliberations.
 to the extent that the agency could propose a suitable role regarding commer-
 cial and industrial uses of asbestos by this winter.  This will be a proposed
 rule.

      We expect that this workshop will provide us with valuable data and in-
 formation, as well as perceptions of the industry, environmentalists, academia,
 and the public.  The more informed we are, as we proceed in our regulatory
 investigation, the better our chances of obtaining an optimal result, namely,
 the elimination of unreasonable risks from exposure to asbestos while minimizing
 the adverse impacts of such a regulation.

      We have structured this workshop to provide us with a broad array of view-
 points regarding the substitutes of asbestos.  We have representatives from
 companies that use asbestos to achieve various product characteristics;  those
 that are suppliers of asbestos;  manufacturers of substitutes;  research scien-
 tists;  concerned private citizens, and others.   We also have representatives
 from industry and elsewhere on the possible asbestos substitutes currently
 available or projected.

      I would like to focus on some of the specifics about the workshop.  The
 kind of information we are looking for covers substitutes for the many uses
 that have been found for asbestos.  We want to know about their technical per-
 formance, their economics, and their effects on human health through the
 environment.

      We have divided these uses  into eight product specific categories,  which
 are  friction products,  gaskets and packings, plastics and floorings, paper
 products,  textiles,  sealants,  asbestos cement sheet, and asbestos cement pipe.
 This  will enable all of  us to  focus on specific areas  of interest and concern,
 and will help us obtain  information and advice from the most qualified people
 in each of the respective fields.   The technical performance of asbestos and
 the economic  aspects of  developing, marketing,  and using asbestos substitutes
will  be  discussed within each  of the category review sessions.

-------
     In evaluating substitutes our initial step is to determine the range of
uses within each.product category.  From this we can find out where substitutes
are available for product categories or subsets of categories and how they per-
form technically.  We want to look at both the general fiber substitutes for
asbestos and at substitutes for specific asbestos products.  We want to know
about the technical limitations of the substitutes present; for what applica-
tions are there no feasible substitutes; and how much has been invested in
research and development to find such substitutes.

     We are also concerned about the economic and practical impacts of conver-
sion to asbestos substitutes.  We are aware that there are many situations
where economics may prevent*the use of a substitute.   Where has this occurred,
and how might the situation be improved?  What are the estimated conversion
costs in the various product industries?  Would industry requirements be
altered significantly, and are there performance standards and regulatory
guidelines that might encourage or inhibit the production or introduction of
any such substitutes?  These are a few of the topics for the Round Table
sessions.

     And, finally, we will be addressing the health aspects of various fibrous
and nonfibrous substitutes, both synthetic and natural.  We will review the
routes of exposure and the results of exposure to various substances, many as
reported in studies and surveys of exposed workers in several industries.

     We have set aside some time for open discussion on the evaluation of cri-
teria for health studies and on the scientific evaluation of substitutes.  We
are here to learn; we have come with open eyes and open ears.  We hope that
you will do the same.  We want to know all sides of the issue, the essential
uses for asbestos, those applications for which there are no feasible substi-
tutes yet available, and those for which substitutes exist and may even be
superior.

     The workshop is not the end of our search for information.  We hope that
it will stimulate your thoughts and generate new ideas.  So, if you have any
additional data, information or comments, or wish to elaborate on any of the
discussion that has occurred during the workshop, we would encourage you to
make that available to us.

-------
                      NON-ASBESTOS FRICTION MATERIALS

                                      by

                          Michael G. Jacko, Ph.D.
                    Bendix   Advanced Technology Center
                            Southfield,  Michigan

                                     and

           Mr.  Charles M.  Brunhofer and Mr. F. William Aldrich*
                     Bendix Friction Materials Division
                               Troy, New York
                                   ABSTRACT

Friction materials for automotive orakes are complex composites containing three
general types of ingredient materials:  reinforcing fibers; modifiers that
adjust or maintain friction level, wear rate, and noise properties; and organic
resin binders.   Historically,  the foundation or major constitutent of automo-
tive friction materials has been asbestos fiber, so chosen because of thermal
stability, friction level,  reinforcing properties, availability, and relatively
low cost.

Numerous substitutes for asbestos in conventional organic materials have been
evaluated, including both naturally occurring and synthetic materials.  Direct
substitution of these alternative materials in conventional formulations has
resulted in poor friction levels, friction  instability, roughness, structural
failure, increased noise, mating surface deterioration and/or front-to-rear
vehicle brake imbalance. Complete reformulation, not simple substitution, is
necessary to meet the numerous,  complex performance requirements of consumers,
manufacturers, and government  standards, such as FMVSS 105-75 and FMVSS 121.

In the 1960fs, a new class  of  friction materials, called semimetallics, was
developed to meet severe braking requirements, primarily in heavy-duty disc
brake and extreme duty truck block applications.  Semimetallics operate satis-
factorily against the ventilated cast-iron  rotors in the smaller brakes of
downsized cars, as well as  against the solid rotors found in the lighter brakes
of new front wheel drive vehicles.  Semimetallics rely on steel fiber and pow-
der metallurgy techniques for  reinforcement, and do not require asbestos.  The
improved performance of semimetallics compensates for their higher costs due
to more expensive ingredients, higher specific gravity, and more costly pro-
cessing requirements.  Overall development  took more than 10 years from intro-
duction to significant customer acceptance.
*Presented by Mr.  Charles M.  Brunhofer

                                       9

-------
    The characteristics of semimetallics make them extremely difficult and costly
    to process as a drum lining segment.  Consequently,  an additional new class of
    friction materials is under development,  specifically for drum lining applica-
    tions.  Additional development effort is  necessary,  not only to confirm the
    performance characteristics of these new  substitute  fiber formulations, but
    also to develop new processing techniques.  These new-type friction materials
    will be more costly, however, due to the  ingredients and new processing
    techniques.
 INTRODUCTION

      Automotive brakes can be viewed, quite  simply,  as energy transformers.
 During a brake application, the friction material (stator) makes contact with
 the rotating drum or disc (rotor), creating  a friction force resisting the
 relative motion between the two bodies.  The energy  of motion is transformed
 into heat energy, which is dissipated, primarily through the rotating member.

      As one might expect, the friction material  must operate in a rather hostile
 environment.  Lining soak temperatures in  excess of  400°C (750°F)  are not
 unusual, and temperatures at the contact interface can exceed 850°C (1560°F).
 The nature of the on-the-road operating environment  (dust, mud, salt, water,
 etc.) complicates the problem.  The  friction material must possess an optimized
 balance of characteristics, and maintain those characteristics throughout
 20,000 to 40,000 miles of vehicle operation.

      The fundamental characteristics of friction materials are listed in
 Table 1.  Friction level must be adequate  and stable over a  wide range of
 operating speeds, application pressures, and temperatures, regardless of the
 conditioning and age of the material.  Of  particular interest are the fade/
 recovery characteristics; i.e., the  ability  to resist friction level deterio-
 ration when subjected to extreme elevated  temperatures (the  fade)  and then to
 return to the pre-fade friction level on cooling (the recovery).   The friction
 material must have good wear properties for  long life, but it must also not
 cause excessive wear or grooving on  the mating disc  or drum.   Excessive com-
 pressibility, noise and roughness (chatter,  vibration, pulsation)  must be
 avoided, and sensitivity to moisture must  be minimized.   Finally,  the friction
 material must be capable of being manufactured with  consistency at a reasonable
 cost.

      Detailed definitions of these characteristics,  and their interaction and
 interdependence, have been discussed at length by Aldrich and Jacko.1  In gen-
 eral,  attempting to improve upon one characteristic  often results  in the deterio-
 ration of other characteristics.  The development of friction materials is
 therefore a complex, interactive process seeking an  optimized combination of
 interdependent characteristics.

      The existence of numerous brake designs  provides another level of com-
plexity in designing friction materials.  Linings for drum brakes  require a
wide  range of properties.   The duo-servo drum brake  (the most popular U.S.
design)  requires two different types of linings,  designated  primary and


                                       10

-------
 TABLE 1.  CHARACTERISTICS OF
           FRICTION MATERIALS

Friction
     •    Level (coefficient)
     •    Stability - speed
                    - pressure
                    - temperature
                    - conditioning
                    - age
     •    Fade/recovery
Wear
     •    Friction material
     •    Drum or disc
Noise
Roughness
Moisture sensitivity
Manufacturability
     •    Processibility
     •    Uniformity
              11

-------
secondary, each of which needs different properties of strength, wear resistance,
friction level and friction  stability.  The non-servo drum brake (used on many
sub-compact vehicles) requires a friction material which encompasses the best
characteristics of the primary and secondary in a single formulation, with
emphasis on low-temperature  properties and static friction capability.  The
large hydraulic and  air-operated drum brakes utilized on medium and heavy trucks
require, in general, the maximum properties of the smaller vehicle linings but
at significantly higher operating temperatures.  The arcuate form of drum brake
linings places additional restrictions on the formulation, because of processing
requirements.

     Disc brakes demand a totally different set of operating conditions for the
friction materials.  Disc brakes generally operate at significantly higher tem-
peratures than equivalent drum brakes, and the front disc brakes run hotter than
the rear drum brakes on the  same vehicle  (Table 2).  The friction material for
disc brakes must be  specifically designed for these higher temperatures, and
must possess a higher coefficient of friction and better wear characteristics
across the temperature range.  Friction-material formulations must also be
tailored to the specific needs of the particular vehicle application.  Numerous
parameters such as vehicle weight, front-to-rear brake balance, actuating system
design, and duty cycle affect the capability of a particular lining formulation
to perform satisfactorily.

     The existence of numerous complex performance standards emanating from con-
sumers, associations, manufacturers, and  government agencies provides an addi-
tional set of parameters that friction materials must meet.  Significant dif-
ferences can exist between friction materials used as original equipment in new
vehicles and friction materials available as replacement parts in the after-
market.  Each vehicle manufacturer has a unique, extensive set of test and
acceptance standards to ensure the safety, durability, and performance of its
products and the components  used therein.  Government-instituted requirements
exist at the federal, state, and local levels.  Federal requirements include
those promulgated by the Department of Transportation (vehicle performance),
the Occupational Safety and  Health Administration (manufacturing work practices),
and the Environmental Protection Agency (manufacturing practices and raw
materials).

     In order to meet the many characteristics outlined thus far, friction mate-
rials for automotive brakes  have developed as complex composites containing
three general types  of ingredient materials:  reinforcing fibers; modifiers
that adjust or maintain friction level; wear rate and noise properties; and
organic resin binders.  Historically, the type of friction materials used in
most automotive applications has been conventional organic friction material.
The foundation or major constituent of conventional organic friction material
has been asbestos fiber, so  chosen because of its unique combination of char-
acteristics.  Asbestos fibers provide reinforcement, possess a high coefficient
of friction, and more importantly, have excellent thermal stability.  The open-
ness of the fiber, its adsorptiveness, and its compactability enhance the pro-
cessing and uniformity requirements.  Finally, asbestos fibers have been avail-
able in a variety of grades at a relatively low cost.
                                      12

-------
              TABLE 2.  BRAKE FADE TEMPERATURES3(°F)
                        (SUBCOMPACT FRONT WHEEL DRIVE
                        VEHICLE)
                       1st SAE fadeb               2nd SAE £adeb
                        (10 stops)                  (15 stops)
                  Disc front    Drum rear     Disc front    Drum rear

Combination 1        780           300           870           360


Combination 2        985           235          1030           240


Combination 3        760           200           855           235

 Temperatures measured before the last stop.  Actual temperatures
 for disc brakes are 80 to 180°F higher, as measured below  the rub-
 bing surface.  Surface temperatures are in excess of 1600°F  (870°C).

bSAE J843c
                                  13

-------
      Once the friction material has been cured, the asbestos fibers are locked
 into the matrix.  During brake operation, the high temperatures generated at
 the interface convert more than 99.7 percent of the asbestos to non-fibrous
 residues (primarily olivine) in the wear debris,2 and less than 0.02 percent
 asbestos becomes airborne.3*1*

      The conventional organic formulations and the processes by which they are
 made have been dependent upon and tailored to the physical and chemical proper-
 ties of asbestos.  Two courses of action are open for elimination of asbestos
 from automotive friction materials:

      1.   Develop a new generation of friction materials,  designed from
           the start without asbestos in mind.

      2.   Attempt to substitute an alternative fiber system for the
           asbestos in conventional formulations, with subsequent mod-
           ification of composition and process techniques.

      Bendix is aggressively pursuing both courses of action.   As Mr.  William
 Agee, our Chairman and Chief Executive Officer, has stated, Bendix is committed
 to being asbestos-free at the earliest possible date within this decade.

 SEMIMETALLIC DISC PADS

 Properties

      In the 1960s, a new generation of friction materials, called semimetallic,
 was developed to meet severe braking requirements which organics could not meet.
 Class A organics (typical U.S.  materials), which perform well in low and mod-
 erate temperature duty, are prone to fade and exhibit compressibility and poor
 wear resistance at high temperatures.  Class B organics (typical European and
 Japanese materials) provide good high-temperature wear and friction levels,  but
 have poor low-temperature wear resistance, produce rotor scoring and/or wear,
 and are prone to being noisy.   Semimetallies were initially develed for these
 extreme, high-temperature applications.5

      Semimetallics rely on steel fiber and powder metallurgy  techniques for  re-
 inforcement.   Various property modifiers are added to enhance performance to
 desired levels,  with a resin binder holding the materials  in  a uniform solid
 mass.   Semimetallics may contain metallic powder, sponge iron particles,  ceramic
 powder, steel fiber, rubber particles, graphite powder, and phenolic resin.6*7
 Some manufacturers utilize a backing layer of a different  composition which
 can contain asbestos.

 Problems Overcome

      Inherent in the uniqueness of the semimetallic formulations and  their per-
 formance properties were a number of significant problems  which required reso-
 lution.   Concentrated development effort was required to resolve both proces-
 sing and performance related issues.   Processing issues included:   the unifor-
mity of the raw  materials mixtures,  the ability to form and handle the in-
process material,  and the ability to manufacture high-quality parts consistently.

                                       14

-------
Performance issues included:  materials strength, cold friction properties,
initial wear resistance, and attachment to the backing plate.   The development
effort on semimetallic friction material has been continuous,  not only to fur-
ther improve its characteristics and properties,  but also to overcome the prob-
lems inherent in accommodating new vehicle applications.

     Semimetallics gained acceptance because they were able to solve some of
the problems that could not be overcome using Class A or Class B organics.
The Improvements/advantages are listed in Table 3.  The key element is the
attainment of overall excellent properties at both low and high temperatures.
Semimetallics cost more because of more expensive ingredients  and a costlier
process, but the improved performance capabilities offset these factors.   An
increased usage of Semimetallics has occurred over the past few years.  The
downsizing of vehicles, with resulting smaller front brakes and higher oper-
ating temperatures has given impetus to increased use of Semimetallics.8   It
is expected that the trend toward asbestos-free semimetallic disc pads will
continue.

SEMIMETALLIC DRUM LININGS

     An obvious alternative to conventional organic drum brake linings is the
use of semimetallic material for drum linings.  In fact, one of the first
applications for Semimetallics was for air brakes on heavy-duty trucks used
in the logging industry—an extremely severe application.

     Significant development effort has been expended on semimetallic drum
brake linings.  However, the basic nature of Semimetallics does not lend itself
to the arcuate segment configuration required for small drum brakes.  The semi-
metallic mix does not possess the necessary green strength, is difficult to
bend into the arcuate shape, and is more brittle in its cured form and there-
fore subject to cracking.  Modifications to the formulation to facilitate pro-
cessibility generally result in a product that cannot achieve commercially
acceptable performance characteristics.

     These difficulties present a clear challenge, and development work on
semimetallic drum brake linings continues.

ALTERNATE FIBERS/REINFORCERS

Properties

     Alternative fiber systems in conventional organic formulations represent
the second course of action open to friction-material manufacturers.  Table  4
is a summary of the properties of some of the various materials which could
be considered as alternate reinforcements.  Since conventional organics and
Semimetallics have traditionally been reinforced with asbestos and  steel  fiber,
respectively, these fibers are also included in the table  for comparative pur-
poses.  The data in Table 4 were obtained from the material manufacturer's
literature and extensive characterization data developed at Bendix.   Charac-
terization included scanning electron microscopy  and x-ray energy spectroscopy
(SEM/XES).  The selection of suitable alternate materials  must also consider


                                      15

-------
TABLE 3.  IMPROVEMENTS OFFERED BY
          SEMIMETALLIC DISC PADS

  Improved energy absorption
  Fade resistance
  •    Temperature insensitivity
  •    In-stop fade
  •    Speed spread
  Friction stability (FMVSS 105-75)
  Higher temperature capabilities (life)
  Rotor compatibility
  •    Scoring
  •    Heat checking
  Reduced noise
  Smaller brake sizing
                 16

-------
                                TABLE 4.   CHARACTERISTICS OF REINFORCING AGENTS
BANE
MANUFACTURER
OMPOSITXOH
(HEIGBT PERCENT)
COST (e/LB)«*
SHAPE
LENGTH (MM)
DIAHBTER (u»)
ASPECT RATIO
SPECIFIC GRAVITY
TENSILE STRENGTH (PSI)
AVG:
THERMAL STABHITf:
UPPER USE TEMP (^)
Tg (°P)
Tfue <°W
»TTop)
HARDNESS (Mph)
MISCELLANEOUS
INFORMATION
ASBESTOS
JM, etc
3HgO.S102.2B20
SlOj
MgO
1.0
FIBER
250+
0.25*
10,000*
2.56
280-440 KPSI
360 RPSI
1200
1600
3.0 - 4.0

FIBERGIIAS
497
OWENS/CORMlNti
E CLASS
S102 54.5
A120S 14.5
00 17.0
HgO 4.5
B203 8.5
H»20 1.0
5.0
FIBER
3175+
13
240+
2.6
450-550 KPSI
500 KPSI
1300
1350
2000
6.5
SILANIZED
MDIBRAL
FIBER
U.S. PIPE
AMD niUHbHX
S102 42
A120, 8
C«0 35
Hgo a
Other 7
1.9
FIBER
28
1-10
40-60
2.7
3-20 KPSI
70 KPSI
1400
1400
2300
6.0 - 6.5
ALSO HINERAL
WOOL
SDZORITE
MICA
MARIETTA
RESOURCES
SiOj 41
Al20j 16
MgO 21
K20 10
F«0 8
Other 4
0.8
PLATE
3175+
2.7
33-37 KPSI
2960
2.5 - 3.0

FIBERFRAX
(CHOPPED)
CARBORUNDUM
S102 47
Al20j 51
Other 2
5.9
FIBER
305
2
150
2.73
400 KPSI
2300
7.0 - 7.5

VOUASTONITE
MOOD BT
HRERPACE (RT)
CeSlOj
CaO.StOa
S102 51
00 47
Other 2
1.0
FIBER
15
2.9
-
1200
1200 (tr)
1540
4.5
SILAHIZED
FORM
AVAILABLE
FRABKUH
FIBER
CERTAIN
TEED
CaSO*
WISKERS
*
0.8
FIBER
SO*
2
25+
3.0
300 KPSI
1800
2100 (tr)
2600
~3.5
SLIGHTLY
SOLUBLE IN
WATER 0.1 g>
GRAPHITE
UFA
UHIOB CARBIDE
99.5Z C
98.9
FIBER
6350+
8.4
750*
1.4
120 KPSI
1200
-1.0

CARBOR
WFA
UHIOH CARBIDE)
912 C
29.6
FIBER
6350*
11
575+
1.4
30 KPSI
1000
-1.0

SOLKA-FLOC
BROWR CO.
CELLULOSE
1.2
FIBROUS
76
18
4
1.4
-
-400
1.0
5.7X
MOISTURE
KEVLAR 29
DUPONT
AROMATIC
POLUHIDB
1007. ORGANIC
19.8
FIBER
6350*
15
423+
1.45
400 KPSI
700
800
1.0

STEEL FIBER
AMERICA!!
STEEL WOOL
SAB 1010
C 0.1
Mn 0.4
S 0.1
Fe 99.4
2.7
FIBER
800-2000
80-100
10+

-
~1000 F
~2SOO F
5.5

 •Fibril Dloettr
"Relative to ubeitoi.

-------
 the health  and  safety implication  of  the  substitute fiber system.  After con-
 siderable study of  existing  information,  Bendix has chosen substitute materials
 which,  in our judgment,  are  free from serious health implications.

 Processing  Conditions

      Current organic friction materials have been developed around the unique
 properties  of asbestos.  Asbestos  fiber bundles open during mixing and entrap
 the friction modifiers and resin,  giving  a  consistent mix.  The compactability
 of asbestos facilitates  forming at room temperature with moderate pressure.

      The non-asbestos fibers are much more  difficult to handle.  Most are very
 brittle and have little  or no surface adsorptivity.  High bulking and segrega-
 tion  occur  during mixing.  Spring  back and  low tack lead to weak structures.
 Combinations of additives and new  processing techniques are required to over-
 come  these  problems and  produce the cohesiveness necessary for manufacturing
 parts.

 Performance Characteristics

      The characteristics of  the fibers can  have significant influence on the
 performance properties of the final composite.  Asbestos has a high, stable
 friction level, good adsorptivity  for strength and wear resistance, and does
 not contribute  to noise.

      Substitute fibers generally show greater frictional instability, little
 or no surface adsorptivity,  and/or significant contribution to both noise and
 mating-surface  degradation.

 NON-ASBESTOS ORGANIC DISC PADS

 Failures on Direct  Substitution

      A  commercial Class  A organic  disc pad  formulation, similar to one reported
 earlier9 and known  to contain phenolic resin, asbestos fiber, organic friction
 particles (cashew and rubber dusts),  zinc chips, and barytes was selected as a
 baseline composition.  In a  series of new formulations, the asbestos fiber was
 replaced with glass fiber, mica, mineral  wool, Franklin fiber, a glass fiber/
 mica  mixture, a glass/Fiberfrax/graphite  fiber mixture, and a glass/Wollastonite
 fiber mixture.

      The composites were run on an inertial dynamometer equipped with a Bendix-
 designed Series III disc brake  loaded to  1000 pounds.  Stops from 50 mph (80
 kmph) at 3.66 mpsps (12  fpsps)  deceleration were run at different initial brake
 temperatures up to  315°C (600°F).   All fiber substitutions produced roughness
 followed by poor  friction.   Generally, the  composites were structurally inade-
 quate producing tear-out and poor  wear resistance, in addition to roughness
 (Table  5).  All formulations were  considered failures.  This led to the conclu-
 sion  that simple  direct  substitution  of alternative fiber systems was not
practical.
                                       18

-------
TABLE 5.  DIRECT SUBSTITUTIONS AND THEIR FAILURES
Formulation
Baseline
b.c.e
d

f
g
h
Reinforcement
Asbestos
Glass
Mica

Glass/Mica
Glass/Fiberf rax/Graphite
Glass /Wollas toni te
Strength
• Strong
No defects
• Pad surface
tearout
• Pad surface
and edge
tear outs
• Weak
• Strong
• Pad surface
tearout
Performance
• Stable friction
Good wear resistance
• Erratic friction, fade, high
pad wear, and scored rotor
• Good friction, SL fade,
high pad, and rotor wear

• Poor friction, fade, and
inner pad wearout
• Roughness, fade, acceptable
pad wear, and scored rotor
• In-stop fade, acceptable
pad wear, and scored rotor

-------
 Alternate Approach

      A new baseline was selected with Increased reinforcement  content to better
 screen the following characteristics:

      •    processing
      •    strength

      •    performance (friction, wear, drum compatibility,  and noise properties)
      •    cost

      The initial objective was improved structural capability.  A number of
 formulations were made using high fiber concentration.  As  shown in Table 6,
 the tensile strength results were very encouraging.   The next  step, which
 proved very difficult, was attaining a proper balance of friction and wear to
 go along with the strength.

 Sample Dynamometer Results

      A series of combinations of materials with a fixed ratio  of glass fiber
 and the other reinforcements was evaluated on a sample dynamometer (Table 7).
 The results indicate that all of these reinforcement  combinations are poor sub-
 stitutes for asbestos fibers in that they exhibit poor friction, poor wear
 resistance, poor friction stability, or poor rotor compatibility.  However,
 some clues were provided and it was possible to combine two of the formula-
 tions to produce a new composite M.  This material was then reformulated with
 additional property modifiers in six other iterations to produce yet another
 formulation S, which exhibited a high but stable friction coefficient, equiva-
 lent wear resistance, and slightly poorer rotor wear  resistance.  At this point,
 the study was transferred to full brake inertial dynamometer testing.

 Inertial Dynamometer Results

      The inertial dynamometer confirmed that formulation S  had a higher fric-
 tion level, slightly better wear resistance, and slightly poorer rotor compati-
 bility than the baseline (Table 8). Approximately 40 iterations of formulation
 S  led to formulation AA which gave good friction with friction stability and
 very good wear resistance.   Further iterations (~10)  led to formulation AL
 which gave lower friction,  poorer wear,  and good rotor compatibility.  In addi-
 tion to  inertial dynamometer tests, a  series of vehicle tests was also
 initiated.

 Vehicle  Test  Results

      Several  formulation iterations were coupled with processing improvements.
 Formulation DA was  developed after  approximately 50 iterations following"Formu-
 lation AL.  Formulation DN  was developed after 13 iterations of a new-concept
material which has  been patented.10 The vehicle test results  (effectiveness,
 fade,  and  recovery,  in addition to  wear  data and noise ratings) are given in
Table  9 and were  run according to a modified SAE J843c schedule.  Formulation
Bendix D7180  is  a Class  A organic used as the baseline.

                                       20

-------
                 TABLE 6.   TENSILE STRENGTH DATA
Formulation
Baseline
A
B
C
u
D
E
B1
Reinforcer
- Asbestos
Glass fiber
Mineral fiber
Wollastonite

Suzorite mica
Glassa
Silanized mineral fiber
Tensile
Min.
3100
3400
600
850

850
2750
2900
strength
Avg.
4000
4800
1300
1500

1400
3500
3150
(psi)
Max.
4600
6350
1850
2350

1750
3750
3250
Deduced
content.
                               21

-------
                                 TABLE  7.   SAMPLE DYNAMOMETER TEST RESULTS
fO
N>
250F
Formulation
Baseline
A
F
G
H
J
K
L
M
S
Reinforcer(s)
Asbestos
Glass fiber
WOL/GF
Mica/GF
MF/GF
FRAX/GF
FF/GF
SOFL/GF
Proprietary
Proprietary
y
0.32
0.32
0.33
0.49
0.32
0.36
0.36
0.35
0.35
0.45
w*
0.002
0.005
0.004
0.004
0.004
0.009
0.003
0.002
0.002
0.002
450F
V
0.28
0.23
0.34
0.19
0.17
0.45
0.50
0.18
0.22
0.45
W
0.004
0.010
0.009
0.010
0.012
0.013
0.005
0.003
0.003
0.006
650F
v»
0.30
0.16
0.16
0.22
0.16
0.50
0.32
0.18
0.18
0.46
W
0
>0
>0
>0
>0
>0
0
>0

0
.022
.080
.040
.060
.080
.200
.016
.080
-
.018
250Rb
RF
1.00
1.31
1.16
1.08
1.37
-
1.75
-
1.20
1.04
RW
2.62
1.70
1.68
2.31
-
-
2.07
-
1.12
2.27
Rotor
Wear
0.0000
0.0003
0.0003
0.0001
0.0001
>0.0005"
0.0001
0.0000
0.0001
0.0001
          All wear  figures  are in inches


          3Rerun used  to provide relative friction (RF) and relative wear (RW) trends after high temperature
          operation.

-------
                        TABLE 8.  INERTIA! DYNAMOMETER TEST RESULTS
Burn

Baseline
S
W
AA
AD
AL
LP*
380
400
400
400
420
440
'Wb
0.
0.
0.
0.
0.
0.
004
003
003
002
003
003
300F
LP
660
400
400
370
650
510
W
0.003
0.003
0.003
0.002
0.003
0.002
450F
LP "
700
300
350
340
600
580
i
-w
0.009
0.008
0.007
0.006
0.012
0.008
600F
LP
490
280
300
390
450
430
W
0.028
0.018
0.015
0.008
0.037
0.034
300F Rotor
LP W
470 0.007 0
0
- - 0
440 0.003 0
330 0.006 0
270 0.004 0
W
.0000
.0007
.0004
.0003
.0002
.0000
a
 All line pressures are in psi.
 All wear figures are In inches..

-------
              TABLE 9.  VEHICLE TEST RESULTS (1977 FULL SIZE STATION WAGON LOADED TO 5540 LBS)
K>
Fronts*
Preburnish effectiveness**
Full system
Post-burnish effectiveness**
Full system
Fronts only
First SAE fade (10 stops)**
Max
(Recovery - 10)
Second SAE fade (15 stops)**
Max
(Recovery - 10)
Post-fade effectiveness**
Full system
Fronts only
Wear (Mils)
Burnish (F/R)
Fades (F/R)
Total pads (F/R)
Total rotor
Noise ratings
Fronts
Rears
Class A organic
D7180
30 MPH 60 MPH
(48 KMPH) (97 KMPH)
500 500
600 600
1180 970
1100 Max
(410)
800 Max
(410)
600 500
900 670
6/6
42/3
48/9
0
10
10
Non-asbestos organics
DA
30 MPH 60 MPH
(48 KMPH) (97 KMPH)
440 460
520 530
1020 900
1000 Max
(380)
800 Max
(360)
450 460
960 850
11/9
33/3
44/12
1.0
8
10
DN
30 MPH 60 MPH
(48 KMPH) (97 KMPH)
440
500
620
(320)
(340)
420
700
11/6
22/2
33/8
1.5
6-8
10
400
420
620
1000
880
460
920


         *A11 tests used same rears (BX4641A/H3133).
        **Line pressures needed for 15 FPSPS deceleration per SAE J843C.

-------
     The line pressure data show that the non-asbestos organics have higher pre-
burnish, post-burnish, and final effectiveness than the baseline,  based on full-
system as well as fronts-only checks.  This higher friction level  and friction
stability are also demonstrated in the fade and recovery portions  of the test.

     Both non-asbestos organics showed poorer burnish wear resistance, and both
showed improved wear resistance during the fade and recovery portions of the
test.  The rotor compatibility of both non-asbestos organics was poorer than
that of the asbestos-based baseline.

     Formulation DA, which is more typical of Class A organics, showed less
loss in rotor wear than did the new-concept DN material.   Both materials were
prone to be noisy.

Status

     Non-asbestos organic disc pads are still in the development stage because
several problems have not yet been resolved:

     •    rotor compatibility
     •    wear durability
     •    noise properties
     •    processing

     Bendix is continuing development efforts to commercialize non-asbestos,
organic disc pads.

NON-ASBESTOS ORGANIC DRUM BRAKE LININGS

Process Characteristics

     Drum-brake linings require different processing characteristics than do
disc pads.  When made by a wet process technique, friction materials require
a binder-wetted plastic mass with good cold flow properties.  When made by a
dry process technique, they require good hot flow properties, but  must first
be capable of being preformed under cold pressure conditions to develop
strength for handling purposes.  Both wet and dry process types require the
capability of ultimate arcuate formation.  All currently known alternate fibers
result in serious problems in these areas.

     As in the case of disc pads, the direct substitution of alternate fiber in
existing asbestos formulations has been unsuccessful.  Basic processibility has
been the first obstacle.  The generally stiff, nonabsorptive alternate fibers
do not result in a wetted, densified mass.  This precludes cold-pressure forming
into brake-lining strip configurations typical of wet process methods.  In the
case of dry-process methods, the fiber stiffness is a deterrent to good physical
integrity of preforms and also leads to excessive lining cracking during bending.
In general, the alternate fiber materials do not result in a mix character which
allows them to be processed effectively by currently known techniques.  The
solutions to these problems call for radically different approaches to material


                                      25

-------
 formulation and processing techniques.   The new processing techniques require
 substantial capital investment.

 Testing and Development

      With the application of suitable material and process changes, non-asbestos
 type drum linings have been experimentally fabricated and  tested.  Hundreds of
 formulations of duo-servo primary linings and secondary linings, along with
 those for non-servo type brake linings, have been made.  When processed  satis-
 factorily, these materials have been tested on sample dynamometers and inertial
 dynamometers before selecting the better ones for vehicle  testing.  The  use of
 different formulations to overcome the  process problems has resulted in  sub-
 stantially different frictional and wear characteristics which have had  to be
 modified to duplicate current materials more closely.

      Table 10 illustrates the magnitude of some of the early problems and some
 of the later results.   Initial tests using very high friction combinations  (A
 and B) run on Vehicle 1 with-a front-brake hold-off valve, resulted in a seri-
 ous duty shift with front brakes projecting greater than normal mileage, and
 the rear brakes projecting short life because of their higher work load.  How-
 ever, when Combination A was run on Vehicle 2 (which had no front-brake  hold-
 off valve), the secondary lining (the same as in Combinations A and B) pro-
 jected almost the minimum requirement of 15,000, although  the primary gave only
 7900 miles.  Subsequent tests of improved combinations,  particularly with
 improved primary lining life,  projected over 20,000 miles.  Tests on Vehicle 3,
 again without a front hold-off value, projected reasonably good life on  Com-
 binations E, F, 6, and H, with quite acceptable life on the more recently
 developed Combination H.  A comparison  of wear projections on Combinations F
 and G shows the importance of primary-secondary teaming.   Both combinations
 had the same primary,  but with different secondaries,  the  life of the primary
 decreased from 20,900  to 12,200 miles.

      The above data illustrates that basic life and performance are achievable,
 at least on certain vehicles.   However, the materials  noted above were prepared
 by more involved,  more expensive processes and are noisier than current  asbestos
 types, and the mating  surface  condition requires further improvement.  Further,
 the ability of these materials to withstand extended in-service usage must be
 evaluated in a wide range of vehicle applications and  environments.

 Status

      The first generation of asbestos-free drum linings  is being evaluated by
 some vehicle manufacturers.  Bendix is  continuing development efforts on further
 improved materials.

 ECONOMIC IMPACT

      The economic  impact of  eliminating asbestos from  automotive friction
materials is significant and includes three distinct segments:
                                      26

-------
           TABLE 10.  LIFE TESTING ON VEHICLES

Front disk
Rear lining Pad life
combination* (miles)
Vehicle 1

Vehicle 2


Vehicle 3



A
B
A
C
D
E
F
G
H
59,600
44,500
31,400
33,200
27,600
31,100
34,800
28,100
21,450
Rear drum brake
• Primary
life
(miles)
3,700
6,600
7,900
20,700
28,300
17,600
20,900
12,200
32,800
Secondary
life
(miles)
8,200
5,900
14,500
26,800
20,400
15,900
16,900
18,700
27,400
*Same type front disc pads for all tests.
                           27

-------
1.   Research and Development/New Capital Investment:  Bendix has
     committed, and will continue to commit, extensive funding to
     both research and development efforts and to the new equipment
     and facilities required to support asbestos-free friction mate-
     rials.  Over the last 5 years, the number of dynamometers, and
     test vehicles at our Friction Materials Division has doubled,
     and engineering headcount has been increased by over 60 percent.
     The total engineering budget has tripled, and the share of the
     budget devoted to asbestos-free product development has grown
     from 13 percent in 1976 to over 71 percent for 1981.  The corp-
     orate research laboratories have also expended significant effort
     in support of the division.  Based on our current plans, Bendix
     estimates that it will have committed over $25,000,000 to engi-
     neering activities on asbestos-free product in the U.S. by 1985.

     Capital expenditures must also be increased significantly.  Over
     the next 5 years, the average annual expenditure related to
     asbestos-free products will be triple the historical average
     annual expenditure for the entire division.  Based on our cur-
     rent plans, Bendix estimates that it will invest over $60,000,000
     (1980 constant dollars) in new equipment and facilities for
     asbestos-free products.

2.   Product Cost:  The basic cost of the product itself is a complex
     function involving many factors.  The amount and types of mate-
     rials used, and the basic raw materials cost are obvious factors.
     The fixed and variable costs of manufacturing can differ greatly,
     based on the type of process and its complexity, production vol-
     umes, labor costs, energy cost, and process yield, among other
     factors.  Administrative costs and handling/distribution costs
     are also significant variables.

     Preliminary cost estimates indicate that asbestos-free drum brake
     linings may cost 20 percent to 50 percent more than current lin-
     ings.  Disc brake pads may cost 20 percent to 100 percent more
     than current materials.  These estimates are for products deliv-
     ered in the original equipment market.  We emphasize these are
     preliminary estimates.  Until parts can actually be manufactured
     on production equipment in significant volumes, costing esti-
     mates must be preliminary.  The estimates are highly dependent
     on the raw materials and processing techniques, which can vary
     significantly.   Moreover, research and development continues,
     and future results can affect product cost.

3.   Implementation Costs:  As noted earlier, vehicle manufacturers
     have an extensive series of stringent test requirements.  Each
     different vehicle configuration requires the series of tests to
     ensure that the product conforms to the requirements.  Since
     asbestos-free materials may have some performance or property
     differences from current materials, vehicle system redesign may
     be necessary.   We do not have sufficient information to accu-
     rately estimate costs associated with the test programs.  We

                                28

-------
          would expect that each vehicle manufacturer would expend millions
          of dollars, and possibly tens of millions, in converting their
          product lines to asbestos-free materials.  A key element is the
          timing of the test programs.  Expenses could be minimized by con-
          verting to asbestos-free materials as part of the scheduled new
          vehicle design programs, where significant brake-system testing
          is already necessary.
 TIMING
     Friction materials development is a lengthy process.  As mentioned pre-
viously, the materials themselves and their properties are the results of
optimization procedures, and the necessary testing programs are extensive.
These programs include not only testing by the friction material supplier to
develop and document the materials' capability, but also extensive testing by
the customer to ensure suitability and regulatory conformance in the particular
application.

     Historical data gives us a sense for program timing.  Evolutionary changes
generally require 18 to 24 months for supplier development and validation test-
ing, and 6 months manufacturing lead-time—that is a total of 3 to 4 years.  An
example of such a change would be an improved organic disc pad utilizing the
same basic components (i.e., asbestos, resin, modifiers).  Compared to its
predecessor, the new formulation might exhibit 15 percent better wear, improved
fade resistance, and the same friction and noise properties.  Today's asbestos
organic linings are essentially the product of 40 years of evolutionary changes.

     Revolutionary changes, which advance the state of the art, are more dif-
ficult to come by.  It is unrealistic to put a timetable on invention, but
establishing the feasibility of a new concept can take 12 to 18 months.
Reducing that concept to a product with some or most of the basic character-
istics can take 12 to 24 months.  Formulation development to obtain a balanced
set of characteristics for commercial application, and validation of those
properties requires 24 to 36 months.  As before, 12 to 18 months for customer
application testing, and 6 months manufacturing lead-time are needed—that is
a total of 5*5 to 8*5 years.  The semimetallic discussed previously is a good
example.

     Semimetallic development began in 1962.  The first low volume, special-
purpose applications occurred in 1969.  General acceptance came in the mid
1970's with the second generation of semimetallic formulations.  Today, semi-
metallic disc pads are utilized on the front brakes of approximately 50 percent
of the new vehicles built in the U.S., and projections approach 100 percent
utilization by 1985.  It has taken continued development and improvement of
semimetallic properties to achieve this level of use.

     The elimination of asbestos from automotive friction materials must be
considered a revolutionary change.  There are strong indications that the
asbestos-free materials can achieve general acceptance more rapidly than semi-
metallies did.  However, basic development needs demand a minimum time from
the start of a program to initial production and application.  Assuming a  1975
start date, historical data would suggest that initial applications could  be

                                      29

-------
 expected in the 1982/83 time frame,  and we believe that we are  close  to  that
 timetable.   However,  this only applies to the first generation  of  asbestos-free
 materials.   Continued engineering effort (evolutionary changes) will  be  required
 to develop  both the second generation of materials with improved properties, and
 the multiplicity of types of formulations necessary for different  applications.

      As indicated earlier, semimetallic disc brake linings containing no asbes-
 tos in either the friction material  or the backing layer are  in use today.  It
 should be pointed out that the semimetallic friction materials  have some char-
 acteristics which may preclude their utilization in certain vehicle applica-
 tions.   An  orderly transition to significantly increased utilization  of  semi-
 metallic disc pads on new U.S. vehicles is in process, and will probably
 approach 100 percent  utilization no  later than 1985.

      Development continues on both asbestos-free organic disc-brake linings
 and on semimetallic drum brake linings, but the timing for production Imple-
 mentation cannot be accurately predicted.

      The initial generation of asbestos-free organic drum-brake linings  is in
 the final development stage at Bendix, and initial evaluations  are underway at
 vehicle manufacturers.   Some asbestos-free blocks are available commercially
 for heavy truck applications.   While it is too early to tell  whether  these
 formulations will achieve commercial success, the first significant production
 release would probably be in 1982.

      Although this presentation has  primarily addressed original equipment con-
 siderations, the use  of asbestos-free materials in the automotive  aftennarket
 will create additional challenges.   As new vehicles are produced with asbestos-
 free friction materials, they should be serviced with asbestos-free products.
 However, since the asbestos-free materials may very well have property and
 performance differences compared to  current friction materials, it may not be
 possible to substitute the asbestos-free materials directly in  older  vehicles
 without compromising  safety.   Hence, significant time and effort will be needed
 to evaluate the effect of new asbestos-free friction materials  in  aftermarket
 applications to ensure safe and efficient braking and adequate  lining life
 prior to the release  of these asbestos-free materials for use in the  aftermarket.

 SUMMARY
                                                                              ji
      Automotive  friction materials  are complex composites that have  developed
 around  the  properties of asbestos.   There is no simple substitution for  asbes-
 tos  fibers  in automotive friction materials.   Extensive engineering programs
 are  required to develop new asbestos-free formulations and process techniques,
 and  to  conduct testing  to ensure the adequacy and safety of the new friction
materials.

      Semimetallic  disc  pads,  originally developed for heavy duty applications,
meet  the criteria  of  being asbestos-free and are in use today.   The trend
 toward  significantly  increased usage is well established.   The  first  generation
of asbestos-free drum linings  for passenger cars and light trucks  is  in  the
final stages  of development at Bendix,  and in the initial stages of evaluation- by


                                       30

-------
vehicle manufacturers.  If these asbestos-free drum linings prove to be com-
mercially acceptable, initial limited production usage could occur as early as
1982.  Some asbestos-free friction materials are currently available on the
market for heavy truck applications.

     Engineering programs continue on Improved versions of the materials men-
tioned above, and also on other types of materials which might prove successful.
Bendix is committed to developing asbestos-free alternatives, and an orderly
transition to such materials is now taking place.  Significant engineering
effort and time is needed to accomplish this transition.

     As stated in the Bendix Corporation's 1979 annual report, "...Bendix early
in the 1980's will offer its automotive customers brakes made with long-wearing
high-performance friction materials that are asbestos-free."  We intend to meet
that commitment.

REFERENCES

     1.   Aldrich, F. W. and M. G. Jacko.  Organic Friction Materials.  Bendix
          Technical Journal.  Vol. 2 (No. 1), 42-54.  (Spring 1969.)

     2.   Jacko, M. G. and R. T. Ducharme.  Brake and Clutch Emissions Generated
          During Vehicle Operation.  Society of Automotive Engineers Transac-
          tions.  JJ2, 1813 (1973); also SAE Paper 730548.

     3.   Anderson, A. £., R. L. Gealer, R. C. McCune, and J. W. Sprys.
          Asbestos Emissions from Brake Dynamometer Tests.  Society of Auto-
          motive Engineers Transactions.  82, 1832 (1973); also SAE Paper 730549.

     4.   Murchio, J. C., W. C. Cooper, and A. DeLeon.  Asbestos Fibers in
          Ambient Air of California.   Final Report.  University of California
          Contract ARB 4-054-1.  March 1973 (also EHS Report #73-2).

     5.   Klein, B. W.  Semimetallic Outer Pads for Disc Brakes.  Bendix Tech-
          nical Journal.  Vol. 2 (No. 3), 109-113.  (Autumn 1969.)

     6.   Rhee, S. K. and J. P. Kwolek.  U.S. Patent 3,835,118, issued
  *       Sept. 19, 1974.

     7.   Jacko, M. G. and S. K. Rhee.  Brake Linings and Clutch Facings.
          Kirk-Othmer Encyclopedia of Chemical Technology.  Vol. 4, 202-212,
          (1978).

     8.   Kwolek, J. P.  Friction Materials for Small Car Solid Rotor Applica-
          tions.  SAE Paper 750874.  October 1975.

     9.   Jacko, M. G.  Physical and Chemical Changes of Organic Disc  Pads  on
          Service.  Wear 46, 163-175 (1978).

    10.   Klein, B. W. and M. G. Jacko.  U.S. Patent 4,175,070  issued
          November 20, 1979.


                                      31

-------
                         DISCUSSION ON  FRICTION PRODUCTS

 QUESTION     (Chairman Guimond) :   You  discussed  quite a bit relative to the
              work that has  to be  done  in  research and development and the
              cost involved  in equipment.   In discussing the increased costs,
              that is  20 to  50 or  20 to 100 percent, depending upon what pro-
              duct line you  were talking about* did these increased costs re-
              flect research and development in the capital equipment writeoffs?
              And  secondly,  could  we also  anticipate, that as you learn more
              about manufacturing  that  the relative costs would come down?

 ANSWER       (Mr.  Brunhofer):  As I tried to indicate in the presentation, we
              separated the  cost discussion into  three segments.  The first
              was  research and development and capital, and since we discussed
              those costs under  that topic, we felt it would not be fair to
              also include amortization of those  costs when we talked about
              product  cost;  therefore,  we  did not include research and develop-
              ment costs or  capital. We simply looked at the manufacturing
              process  and the types of  materials, as best we could identify
              them,  and did  cost studies on the cost of the materials.

              Part of  the variance that we put into the discussion of increased
              costs  has to do with estimates on what our effectiveness will be
              as the process gets  started.  Obviously, with semimetallic
              materials,  there is  a significant body of knowledge available.
              The  variance there,  as I  tried to indicate, is more with respect
              to what  the base line material is,  as opposed to any new process
              development.   But in the  area of drum brake linings, where we
              feel we  are close, and in the area  of semimetallic drum and sub-
              stitute  fiber  disks,  we simply do not have any method of running
              production materials at this time.  The capital equipment is on
              order, but  it  is not in place, and  until we get those lines
              running,  it is very  difficult to come up with firm numbers.

QUESTION      (Mr. Fenton):   I am  from  Marietta Resources.  To what extent have
              you been codeveloping,  or working with any of the suppliers who
             may be competent or  able  to modify  drum brake linings?

ANSWER        (Mr. Brunhofer):  We have worked with suppliers.  We recognize
              the fact  that  their  knowledge as to treatments of materials for
              our specific application  can be very helpful.  Other than that,
              it is  a  source of information we have used and we will continue
              to use and look forward to anything that anyone might have to
             offer  in  that  area.
                                      32

-------
QUESTION     (Mr. Wing):   I represent Dow Chemical,  which neither makes brake
             linings nor  any components  that go  into them,  so my concern as a
             citizen is the cost of regulation.   Based  upon the Bendix report,
             I believe there is about one ton of airborne asbestos,  produced
             annually from passenger cars,  and a total  of about three times
             that amount, scattered over an area of  about 3,000 miles by 2,000
             miles.  I cannot conceive that that presents an unreasonable risk,
             so why are we even talking  about substituting asbestos?

ANSWER       (Chairman Guimond):  No, I  would rather not  get into the bad or the
             good points  of why we should or should  not regulate asbestos at
             this stage from the standpoints of  a health  hazard.   Clearly,
             there are problems with the various occupational exposures;  but
             nonetheless, we appreciate  your comment.

QUESTION     (Mr. Castleman) :  I would like to know  if  you deal in international
             as well as domestic markets, and what interest is there from
             foreign automobile manufacturers and foreign governments in pro-
             ducts that you talked about today?

ANSWER       (Mr. Brunhofer) :  In answer to your question,  yes, we do deal in
             international markets.  Most of what I  have  addressed today has
             to do with the business of  the Friction Materials Division of
             Bendix, which is the U.S. operating arm.   Bendix also has divi-
             sions involved in friction  materials worldwide.  Those  divisions
             also have programs with respect to  friction  materials in their
             own market places and with  their own customers.

             There is international interest. For a while, the interest in
             the U.S. was more intense than the  interest  in Europe;  then for
             a period of  time, the interest in Europe became very intense.
             There are materials under evaluation in Europe.  The Japanese
             have been interested.

             We have tried to work with  our customers (vehicle manufacturers)
             to keep them informed of the situation  as  we see it, and that
             does include not only the U.S. and  U.S. auto makers but also
             international markets, both as they pertain  to those marketplaces
             themselves and the products that may come  into the U.S.

QUESTION     (Mr. Castleman):  At this point is  the  United States at the
             leading edge, in commercially developing and using the substitutes
             or do you find there are other countries that are in an equivalent
             position today?
                                     33

-------
ANSWER
QUESTION
ANSWER
 (Mr. Brunhofer):  I am not really an expert in that area.  Just
 from top-of-the-head knowledge, I would say the European market
 is about even.  As I understand the European market right now,
 it is roughly at the state where there are products that are being
 evaluated by the suppliers and by the vehicle manufacturers.  I
 believe in one  or more of the Scandinavian countries there is
 legislation that either severly limits or totally bans the use of
 asbestos.  I am not 100 percent positive in that area.

 (Mr. Moon):  I  am with Jim Walter Research Corporation.  I would
 be interested in knowing what kind of criteria you use in looking
 at substitute fibrous material?  What kind of health information
 do you require  in evaluating substitute fibers?  Is it specific
 or is it general?

 (Mr. Brunhofer):  Some of it is rather specific; some if it is
 obviously general.  Primarily, we have looked at the information
 available in the literature.  We have worked with the suppliers.
 One of the things we have special concerns about is fiber size.
We feel it is a very important issue and we have made some judg-
ments as to what size fibers we will and will not use.  And that
 is one of the restrictions on any fiber that we will consider.
 Obviously, a second very important aspect is the capability to
withstand severe use and that eliminates many fibers.  We also
have some concerns as to what is going on at the fiber surface.
We are seeing extremely high temperatures at the surface.  We
wonder what the byproducts might be of some of the substitute
materials, and  this is an area that I think is in its infancy.
 I do not want to be more specific than that but those are some
 of the considerations.
                                     34

-------
                            GASKETS AND PACKINGS

                                      by

                           Mr. Stephen D. Koehler
                          Greene,  Tweed and Company
                          North Wales, Pennsylvania
                                   ABSTRACT

    ALTERNATIVES TO ASBESTOS AS A BRAIDED PACKING MATERIAL

    The advantages of asbestos packings are that they are strong, inexpensive,
    and are  resistant to heat and chemicals.  Disadvantages are that they are
    very abrasive and have poor heat dissipation.  Substitutes for asbestos
    packings are available.  To properly evaluate their performance, mechanical
    (pressure, velocity), chemical (acidity,  causticity), and thermal
    (environmental, friction) factors must be compared to those of asbestos
    packings.  The costs of non-asbestos packings might seem higher than those
    of asbestos packings.  However, when maintenance and operating costs are
    considered, the newer synthetic packings  are competitive.

    GASKETING

    Commercially available non-asbestos gasketing materials include vegetable
    fiber, cork composition, plastics, rubber, graphite, beater-saturation
    materials, and metals.  Performance characteristics.of these materials
    are discussed and compared with those of  asbestos-containing gaskets.
ASBESTOS AS A BRAIDED PACKING MATERIAL AND ALTERNATIVES

     Asbestos yarns are the most  common materials used in the manufacture
of braided and woven packing materials, used as sealing devices  in fluid
processing and fluid power equipment.   Braided packings are technically
compression packings, because of  the manner in which they perform, the
sealing function.   Made from relatively soft, pliant materials,  compression
of Jam packings consist of a number of rings which  are inserted  into the
annular space (stuffing box) between the rotating member and the body of
the pump or valve.   By tightening a follower or packing gland against the
top ring, pressure is transmitted to the packing set, expanding  the rings
radially against the side of the  stuffing box and  rotating member,
effecting a seal.
                                      35

-------
      Compression  packings  find  their major uses  in the process industries
 such as  petro-chemical,  paper and  steel mills, and in services such as
 utilities, marine, water,  sewage,  food and nuclear power.  They seal all
 types of fluids-water, steam, acids, caustics, solvents, gases, oil, gasoline
 and  other chemicals—over  a broad  range of temperature and pressure con-
 ditions.  They  are used  in rotary,  centrifugal and reciprocating pumps,
 valves,  expansion joints,  soot  blowers and many  other types of mechanical
 equipment.   There are dozens of manufacturers of compression packings and
 thousands of marketing outlets, when you  consider the fact that the
 majority of  compression  packings are sold through local industrial
 distributors.

      Compression  packings  are made up of  two or  three components.  The most
 important component  is the yarn, which is made up of fibers or filaments
 spun together to  produce a material which can be braided to form the body
 of the packing.   This yarn gives the packing shape and is the strength
 member of the packing.   Asbestos is the most common base material of which
 yarn is  made for  braided packings.  The other two components are the
 suspensoid which  fills the interstices in the braid and acts as a blocking
 agent, and the  lubricant which  reduces the frictional drag of the body
 materials on the  shaft,  to reduce  heat build-up  and energy requirements to
 operate  the  pump.

      Asbestos has been used as  a body material for compression packings for
 four main reasons.   First  of all,  it is a very strong material.  It can
 withstand the mechanical beating and abrasive attack found within the stuff-
 ing  box  area of a pump.  Second, it is highly resistant to chemical attack,
 holding  up to fluids from  pH of 2-14.  Thirdly,  it is temperature resistant.
 AAAA asbestos can withstand temperatures  up to 1000F.  Fourth, and probably
 the  most important reason  for its  use today, is  that it is a relatively
 cheap material.   Raw asbestos yarn sells  for less than $2.00 per pound, when
 purchased in large quantities.

      The disadvantages of  asbestos, from  an application engineer's stand-
 point, are as great  as the advantages.  Asbestos is a mineral, mined from
 the  ground in rock form.   To get it to packing yarn form, the asbestos fiber
 is spun  around  a  carrier filament  such as cotton or TFE.  Asbestos fiber is
 very abrasive,  acting much like a  grinding wheel, when the yarn is
 compressed against a rotating shaft (as in a stuffing box).  The suspensoid
 and  break-in lubricant protect  the shaft  for awhile, but eventually the raw
 asbestos contacts the shaft or  sleeve, causing scoring and eventual de-
 struction of the  component with which it  comes in contact.  Unfortunately,
 this process is often aided by  the untrained maintenance man, who over-
 tightens the packing gland, to  reduce the pump drippage.  As he does this,
 heat builds  up, because  of frictional drag.  We  are all familiar with
 asbestos as  an  insulator,  basically to hold the  heat in or out of our houses.
 The  same thing  happens within the  stuffing box—with disastrous results.
 The  trapped  frictional heat boils  all the lubricant and suspensoids out of
 the  packing.  The built  up heat then has  no place to go but along the shaft,
 eventually overheating the bearings, causing a failure and shutdown of the
whole pump for major repairs.   To  keep this from happening, all packing


                                    36

-------
manufacturers and pump manufacturers recommend a fairly generous flow of
pumpage to be allowed to leak past the asbestos packings,  to provide a
cooling flow, and also a fluid film for the packing to ride on rather than
the metal surface of the shaft.  In some cases, an outside source of cooling
and lubricating fluid is injected into the stuffing box area, through a
porous ring called a lantern ring.

     In spite of the problems just described, a well-trained maintenance
crew could get reasonable life out of a set of packing, or what they thought
was reasonable life because they had nothing with which to compare.   In the
1950's, the development of teflon, by DuPont, began the era of the synthetic
packing yarn.  Teflon covered a wide range of applications with a pH range of
1-14, temperatures up to 500 F, and shaft speeds up to 1200 FPM.  Its heat
dissipation is poor, and not only that, it expands when heated at a rate
ten times higher than the metal around it.  So for a different reason we
get the same mode of failure.  In the 60 *s and 70* s, other synthetic packings
were developed, the state-of-the-art now being the carbonaceous fiber packings.

     Table 1 outlines the most important packing fibers in use today, showing
their advantages, disadvantages, and most common usage.  TFE impregnated
Aramid fiber is becoming the most pjpular asbestos substitute for service
within the pH range of 3-11, for temperatures up to 500°F, and for shaft
speeds under 2000 FPM.  Its strength and non-contaminating qualities account
for its popularity in such industries as pulp and paper and waste water
treatment.  Another popular packing fiber is Graphite/TFE composite.  Its
wider pH range of 1-14, and greater heat dissipation, makes it more versatile
than Aramid or pure teflon.  Its only drawback is its color, which is gray,
causing some concern where color contamination could be a problem.  The
carbonaceous fiber packings, as stated above, are the first choice for all-
around service superiority.  They cover almost any process fluid, except for
the very volatile strong oxidizers, such as oleum, fuming nitric acid, aqua
regia and fluorine.  For this reason, these products are approaching truly
"universal packing" status, and once their usage becomes widespread, the
economics of scale will bring their costs within the range of the synthetics
which preceded them.

Performance of Asbestos Substitutes

     In the selection of a dynamic service packing, two important criteria
are the PV and the pH factors.

     The PV factor, which is the  factor for mechanical  conditions,  is
determined by multiplying the pressure on  the  stuffing  box by the velocity
of the shaft.  The resultant PV factor will  pinpoint  a range of applicable
packings .

          PV Factor = Pressure on stuffing box (PSI) multiplied by
                      velocity of shaft  (FPM)
                 PV =  2/3 discharge  pressure x      x Shaft Diameter x 3.14)
                                      37

-------
                                                         TABLE 1.   FIBER USAGE  CHART
                 Fiber
                           Advantages
                                                                        Disadvantages
                                          Most  common usage
00
             Asbestos        Heat resistant, pressure resis-
                             tant, strong (tear resistance),
                             availability, price.
             Aramid          Super strong, tear resistant,
                             flexible, lowest priced
                             synthetic fiber, non-staining,
                             long service life.
Graphite/TFE    Reduces run in time, chemical
Composite       resistant, low thermal expan-
                sion, nonscoring, good heat
                dissipation, light weight
                (more feet/lb), not messy,
                nonstaining, flexible, will
                not extrude, a product you
                can standardize on.  Great
                in valves, long service life.

TFE             Low friction, chemical resis-
                tance, nonstaining.
             Carbon          Heat dissipition, takes high
                             shaft speeds, least expensive
                             in the carbon/graphite family,
                             temperature resistant to
                             1200"F, operated with a lower
                             drip rate, repack costs
                             reduced total,removal not
                             always necessary.

             Graphite        Heat resistant, heat dissipa-
                             tion, fastest shaft speed,
                             chemical  resistance, long
                             service life, light weight,
                             near zero thermal expansion,
                             near zero drip rate, a viable
                             alternative to the mechanical
                             seal, will not harden.
                                                  Heat insulator,  abrasive,
                                                  health hazard, messy,  low
                                                  service life,  fluid
                                                  compatibility.

                                                  Hard to cut, cannot be die
                                                  formed, 3-11 pH  range  500
                                                  temp, limit.
                                                               If over tightened, it may
                                                               glaze, possibly price.
Thermal exoansion, low shaft
speed, SOO°F limit, possible
price.

Brittle, possibly price.
                                                  Brittle, frays, price.
                                  Depending  on braid and  lube:
                                  General  service  pumps,  valves,
                                  etc.
                                  Papermill-stock pumps hydro-
                                  finers,  etc.,  sewage treatment
                                  plants-centrifugal  sludee  pumps,
                                  etc.,  all  slurries  in the  3-11 pH
                                  range.   Possible future  to
                                  replace  all TFE/Asbestos.

                                  Chemical pumps, especially effec-
                                  tive on  chemical slurries,
                                  sewage/slurries, general service.
Chemical pumps and valves,
food and drug pumps and valves,
nonstaining applications.

The best boiler feed pump
packing going especially the
large ones in power plants,
chemical pumps, boiler recircu-
lating pumps, this is a good
general power plant packing.
                                  In the dry form it is  used  in
                                  high temperature valves in  power
                                  plants, high speed-low drip
                                  rate pumps, very hot chemicals,
                                  chlorine agitators, exotic  high
                                  temperature and highly corrosive
                                  materials.

-------
     The Fluid Sealing Association has developed a chart showing this range,
and it has been reproduced in this treatise as Table 2.

     The pH factor is a numerical measurement of the intensity of severity
of an acidic or caustic solution.  This is the measurement of chemical attack
which a packing will encounter.   Tables 3 and 4 cover the pH values, and
shows which packings are applicable to a specific pH factor.

     The third criteria, equally important as the first  two, is resistance
to temperature.  Aramid, Teflon and Graphite/TFE composites are generally
limited to 500°F.  Carbon Yarn is rated to 1200°F in steam or 650°F in
oxidizing atmospheres.  Pure Graphite goes all the way up to 6000°F in non-
oxidizing atmospheres, 1200°F in steam, and 800°F in oxidizing atmospheres.
An important factor to consider as far as temperature goes is frictional
heat.  If the surrounding atmosphere in which the packing must perform is
close to the temperature limit of the packing (within 75-100°F) , then care-
ful attention must be paid to proper break-in of the packing, and maintaining
adequate drip rates to enhance cooling and heat transfer away from the packing
and delicate pump components.  Even though packing materials such as graphite
could withstand the heat, the crystalline structure of the metallic pump
components could be altered, causing degradation and failure, or else oil
seals and bearings may succumb'to the heightened temperatures, also causing
shutdown for major overhaul.

     Table 5 represents an attempt to compare the various packing materials
discussed in this treatise in some meaningful, practical way.  It is titled
"Experimental Preference Rating Chart", because the ratings are based on our
experience in the field, and take into account more than just the three
factors discussed previously.  We have set up hypothetical examples of
applications which could be found in almost any of the process industries.
Service life of the packing, efficiency of energy usage, and equipment life
are the three criteria which we give an experimental rating.  One hundred
is the highest a product can be rated and zero is the lowest a product can
be rated.

The Economics of Change Over to Asbestos-Free Braided Packing

     Braided packings are sold to the MRO user directly  by the manufacturer
and through industrial distributors on a per pound basis.  Table 6 shows
the comparative cost per pound of the most often used packing materials, in
a ready to use braided form.  Graphited and TFE impregnated asbestos re-
present probably 60-80 percent, in poundage, of all the  heavy duty packings
sold today.  Even though braided packings are sold on a per pound basis, to
understand the cost of using a specific packing, it is more relevant to talk
about costs per packed stuffing box.  Table 7 gives us this comparison.

     Studying these charts, it would seem that there will be some economic
hardship for the user to switch over to the asbestos-free packings.  The
truth is, that when all the costs are taken into account, the non-asbestos
packing becomes the most cost effective alternative.  The examples  shown  on
Table 8 very clearly show that because of the superior life  characteristics,


                                      39

-------
TABLE 2.  PV FACTORS
Surface
velocity,
Pressure FPM PV factor
0-50 PSI 52-916 45,800



51-100 PSI 916-1885 	 188,500



101-174 PSI 916-1885 328,000



175-250 PSI 916-1885 471,300



Stuffing box
temp., "7 Aramid
50-150 X
151-500 X
501-600
601-750
50-150 X
151-500 X
501-600
601-750
50-150 X
151-500 X
501-600
601-750
50-150
151-500
501-600
601-750
Graphite /TFE
Carbonaceous TFE composite
X X
X X
X
X
X X
X X
X
X
X X
X X
X
X
X
X
X
X
X
X


X
X


X
X


X
X



-------
                   TABLE 3.   pH VALUES
14 Very severe caustic

13
12 Severe caustic
11

10
9 Mild caustic
8
7 Neutral (distilled water)
6
5 Mild acid
4

3
2 Severe acid
1

0 Very severe acid

The pH factor is a numerical measurement of the intensity
of severity of an acidic or caustic solution.   In addition,
the degree of concentration of the pump fluid will effect
packing selection, and it also must be taken into con-
sideration.  From Table 3 you can select the materials
which are suited to the pH value of the fluid.
                           41

-------
    TABLE 4.  pH FACTOR DETERMINES CORRECT
              PACKING MATERIALS

 pH                       Applicable packing
range                          materials

0-1                     TFE Fiber
                        Carbonaceous Fiber
                        Graphite Tape
                        Graphite/PTFE Composite
                        PTFE Impregnated Carbon

2-3                     TFE Fiber
                        Carbonaceous Fiber
                        Graphite Tape
                        Graphite/PTFE Composite
                        PTFE Impregnated Carbon

4-5                     TFE Fiber
                        Carbonaceous Fiber
                        Aramid TFE-Dispersion
                        Graphite Tape
                        Graphite/PTFE Composite
                        PTFE Impregnated Carbon

6-7                     TFE Fiber
                        Carbonaceous Fiber
                        Graphite Tape
                        Cellulostic
                        Aramid TFE-Dispersion
                        Graphite Tape
                        Graphite/PTFE Composite
                        PTFE Impregnated Carbon

8-9                     TFE Fiber
                        Carbonaceous Fiber
                        Cellulostic
                        Aramid TFE-Dispersion
                        Graphite Tape
                        Graphite/PTFE Composite
                        PTFE Impregnated Carbon

10-11                   TFE Fiber
                        Carbonaceous Fiber
                        Aramid TFE-Dispersion
                        Graphite Tape
                        Graphite/PTFE Composite
                        PTFE Impregnated Carbon

                  (continued)
                      42

-------
              TABLE 4 (continued)
 pH                       Applicable packing
range                          materials

12-13                   TFE Fiber
                        Carbonaceous Fiber
                        Graphite Tape
                        Graphite/PTFE Composite
                        FTFE Impregnated Carbon
14                      TFE Fiber
                        Carbonaceous Fiber
                        Graphite Tape
                        Graphite/PTFE Composite
                        PTFE Impregnated Carbon
                      43

-------
              TABLE  5.   EXPERIMENTAL PREFERENCE RATING  CHART
 Application data
  Service 1
  Service 2
    Service 3
Motion
Fluid
Temperature
Shaft speed
Discharge  pressure
Drip rate
Flush
Rotary
Clear, neutral
200°F
800 FPM
50 PSI
100 drops/tnin
No
Rotary
slurry, pH 6-8
200°F
800 FPM
50 PSI
100 drops/min.
Yes
Rotary
Acid slurry, pH 2
400°F
2000 FPM
150 PSI
20 drops/min
Yes

Service life
Energy use
Equipment life

Service life
Energy use
Equipment life

Service life
Energy use
Equipment life

Service life
Energy use
Equipment life

Service life
Energy use
Equipment life

Service life
Energy use
Equipment life
Asbestos
40
10
5
Aramid
60
60
70
Graphite/TFE
composite
90
80
80
Teflon
90
90
60
Carbon
95
90
90
Graphite
100
100
100
Asbestos
40
10
5
Aramid
100
60
70
Graphite/TFE
composite
90
80
80
Teflon
90
90
60
Carbon
95
90
90
Graphite
100
100
100
Asbestos
10
10
5
Aramid
10
60
70
Graphite/TFE
composite
100
80
80
Teflon
25
90
40
Carbon
95
90
90
Graphite
100
100
100
Note:  100 = Highest efficiency
        50 = Satisfactory
        30 = Unsatisfactory
                                    44

-------
 TABLE 6.  BRAIDED PACKINGS USER COST/LB
The following chart is based on a 1 Ib
unit of interbraided packing material.
The packing cross-section (square) is
3/8".
        Material                Cost/lb*
Flax                            $  9.50
Cotton                             9.60
Graph!ted asbestos                13.50
TFE impregnated asbestos          23.00
Aramid                            37.50
PTFE                              61.00
PTFE/Graphite                     69.50
Carbon                           111.50
Graphite                         170.50
*Cost/lb is based on an average user list
 price of four major suppliers.  Actual
 cost may vary due to quantity buying or
 other variable factors.

-------
JS
ON
                              TABLE 7.  BRAIDED PACKINGS COST PER PACKED STUFFING BOX

             The following chart is based on packing a pump, valve, mixer or similar rotating shaft
             driven component.  The sealing rings are located in a housing called a stuffing box.
             Our model for this chart requires five sealing rings per stuffing box.  The packing is
             braided interbraided style, and is 3/8" square cross-section.  Costs shown are based
             in industry norms, and could vary with different suppliers.
Shaft
diameter
1"
IV
2"
2V
3"
3V
4"

Oraphited
asbestos
$2.68
3.52
4.65
5.64
6.48
7.61
8.60

TFE/Impreg.
asbestos
$ 4.29
5.72
7.36
9.00
10.43
12.57
13.50

TFE impreg.
aramid
$ 6.45
8.60
11.11
13.62
15.77
18.28
20.43

TFE/Graphite
composite
$10.50
13.78
17.72
22.31
25.59
29.53
32.81

Graphite impreg.
carbon
$12.00
16.80
21.60
26.40
31.20
36.00
39.60

Shaft TFE impreg. Graphite impreg.
















diameter
1"
IV
2"
2V
3"
3W
4"
TFE
$13.06
17.42
22.86
27.76
32.12
37.57
41.92
graphite
$21.17
28.87
36.57
46.20
53.90
61.60
69.30









-------
TABLE 8.  ONE YEAR TYPICAL OPERATING/MAINTENANCE COSTS
          PACKING A PUMP WITH ASBESTOS BRAIDED PACKINGS
          VERSUS SYNTHETIC PACKINGS

1.
2.
3.
4.
5.
Economic factor
Expected packing life
Packing set costs (1)
Labor to repack (2)
Sleeve replacement
Energy consumption (3)
Total
Graphited
asbestos
4 months
$ 13.95
90.00
300.00
480.00
$883.95
Graphite/TFE
composite
12 months
$ 17.72
30.00
00.00
384.00
$431.72
Minimum 1 year savings per packed pump by using non-
asbestos packing is $452.23.

Other variable cost factors inherent with continued
usage of asbestos packings:

    1.  Downtime costs while repacking glands and/or
        replacing sleeves.

    2.  Downtime costs, labor costs, parts costs to
        replace bearings damaged due to heat build-up
        caused by high friction and poor heat dissipa-
        tion qualities of asbestos packings.

    3.  Product loss necessitated by high drip rates.
        Also clean up and housekeeping costs.

NOTES:  (1)  Based on 2" diameter shaft, 3/8" cross-
             section packing 5 rings per set.

        (2)  Based on 2 men, 1 hour per repack, $15.00
             per man hour.

        (3)  Based on 2 kw/hr for pump packed with
             asbestos, 1.6  kw/hr for pump packed with
             synthetic packing.  (Assuming 20 percent
             differential due to friction, actual
             differential will be greater), 4000
             operating hours per year.
                          47

-------
lower  friction, and non-abrasiveness of the alternatives, non-asbestos packing
should be  the  first choice of packing users, irrespective of the other prob-
lems associated with asbestos usage.

     The packings industry has  for many years been marketing and recommending
asbestos-free  packings  as the most cost effective seals for all types of
rotating equipment.  Original equipment manufacturers and maintenance personnel
have resisted  this movement, mainly for economic reasons.  Much time and
money  has  been spent educating  these two packing users on the benefits of the
asbestos-free  alternatives.  The major cost then, to the manufacturer of braided
packings is not in capital equipment, but in training sales and engineering
people to  overcome the  resistance to changing over to non-asbestos packings
because of the lack of  understanding of the problems of asbestos usage.

What Effect will the Change-Over to Asbestos-Free Materials Have on
the Packings Industry?

     The packings industry will be very happy to see the day when there is
a total change-over to  asbestos-free packings.  There are various reasons for
this.

     First, it is in our, and our customers, best interest to supply the best
product for a  given application.  When asbestos packings were invented and
developed, they were the best product then available.  Asbestos packings have
been used  for  so long,  that they have become the standard.  The newer synthetic
packings have  capabilities which make them much preferable.  The resistance
to their usage, based on ignorance of the over-all operating costs of
utilizing  asbestos packings, will eventually be overcome, but it is costing
both the manufacturer of packings and the user money, in the meantime.

     Second, because the synthetic fibers can be applied in every application,
elimination of asbestos as a packing material will allow us to concentrate
our resources  on fewer  products, allowing us to stock a better range of sizes,
while  at the same time  cutting  our costs for advertising and training.  We
will be able to make more efficient usage of our braiding equipment and labor,
as we  do not have to set-up for asbestos any longer.  We will have less
expenditures for housekeeping and monitoring equipment to ensure our workers
safety.

     Finally,  we can eliminate  the danger of future legal entanglements, and
the drain  on our resources which accompany such involvement.  Any manufacturer
that has had any asbestos in any of its products is subject to enjoinment
in class action suits,  and this has us constantly looking over our shoulder.
The sooner that the pump manufacturer, and the pump operator, is forced to go
to alternative packings materials the better.

GASKETING

     Back  in the days of the Roman Empire, a system of aqueducts was con-
structed to carry water from distant points to the cities.  Some sort of
material was required to provide a seal between pipe sections since
                                     48

-------
surfaces smooth enough to seal against each other could not be manufactured.
The Romans in many instances decided upon flax rope that had been dipped
in animal fat, as a very workable solution - and to our knowledge the first
recorded instance of gasket use.

     Through the years as process temperatures and pressures began to rise,
and more reactive fluids came into use, better and better materials had to
be found.  One of the best turned out to be the combination of long asbestos
fibers and high temperature rubbers.  Put together with the asbestos serving
as the strength member and heat resisting material, and the rubber as the
binder and sealing material, gaskets cut from compressed asbestos sheet
have found extensive use in virtually every plant in the world.

     Even in temperatures well in excess of the char point of the rubber
binder, compressed asbestos will still provide a seal.   The remains of the
rubber and the filler are held in place by the thick matrix of the long
asbestos fibers and the axial pressure exerted by a tightly bolted pair
of flanges.  And at moderate temperatures between a good pair of flanges,
pressures in excess of 2500 psi have easily been sealed.

The Asbestos Problem and the Alternatives

     Today, with the health hazard of asbestos becoming well known, manu-
facturers have been hard at work in an attempt to develop gasketing mate-
rials that would offer physical and chemical characteristics similar to
those of compressed asbestos.  Some of the materials currently commercially
available are:  vegetable fibre, cork composition, cork/rubber, plastics,
beater-saturation materials and metal.

Vegetable Fibre Sheet—
     Made of plant fibers and a binder, it is mostly used for solvents, fuels,
air, gases and refrigerants with temperatures to 250°F.

Cork Composition—
     Produced from ground cork granules and protein or synthetic binders;
cork is used where light bolt loading is a must (glass and ceramics for
example) in water, lubricating oils and petroleum derivatives to 250°F.

Plastics—
     Of all the plastics, one has emerged as the most common:  PTFE.  PTFE
can be used in virtually all fluids to 500°F, but in its virgin state can
creep (cold flow) under flange loading.  Thus PTFE is commonly found loaded
with glass or carbon fibers to reduce creep relaxation.

Expanded PTFE—
     A micro-porous PTFE structure, expanded PTFE offers high  tensile
strength, virtually no significant cold flow and extremely high compress-
ibility.  Coupled with PTFE's legendary fluid resistance and wide.
temperature capability (-450°F to 600°F), this material is one of  the most
significant replacements for compressed asbestos gaskets now on the market.
                                    49

-------
Rubber—
     Both natural  and  synthetic rubbers  are used, with or without a strength
member of woven wire or  cloth.  Normally sheet rubber gasketing is manu-
factured in  a durometer  (hardness)  from  55 to 80  (Shore A) and varies in
thickness from 1/32" to  1/4".  See  Tables 9, 10,  and 11 for the various
properties of each rubber.

Graphite—
     Manufactured  of pure graphite, this material is available with or
without wire reinforcement  in  thicknesses from .030" to .120" and up to
26" x 26" in size.  Suitable for  use in  most fluids to 3000°C.

Beater-Saturation  Materials—
     Manufactured  using  a process similar to that of making paper (where the
binder is deposited uniformly  over  the individual fibres while suspended in
water), these materials  can replace compressed asbestos sheet in most of the
same fluids  although with temperature limits in the area of 350 to 500°F.
(Note:  much of the research on asbestos sheet replacements falls into this
area.)

Metal--
     When very high temperatures  and/or  pressures are encountered, spiral-
wound gaskets are  normally  specified.  Manufactured of continuous vee-
shaped metal strip wound radially with a soft high temperature material
between each layer, they can be designed for most applications.

The Mechanics of Gasketing

     Simply  put, a gasket is used to create a static seal between two
stationary members of  a mechanical  assembly confining a liquid or gas
under vacuum or pressure.   While  complex formulas are used to determine
gasket design and  material  selection, a  few simple rules can provide the
user with enough information to properly select the right gasket most of the
time.

     Figure  1 illustrates the  static forces acting upon a gasket.

     In addition to the  static forces, 3 other factors affect gasket
material selection:

     1.    Temperature:  As  temperature increases  or decreases, metals
          expand or contract.  This affects bolt  loading and can cause
          softening of the  gasket (creep relaxation) or burn-out of
          the binders.

     2.    Medium:   Highly reactive  fluids (acids, caustics, plastics,
          solvents, etc.) readily attack many binders, thus care must
          be taken  in specifying  the correct material with each fluid.

     3.    General Conditions:  The  type  of flange (see Figure 2), the
          surface finish (where the surface may range from a rough
                                      50

-------
                                       TABLE  9.   RUBBER PRODUCTS
                 New ASTM
                 reference
Features of the more commonly used
 elastomers in gasketing materials
 BUNA-S OR GRS     SBR        Good mechanical properties;  economical; extensively seen as the common
                              "red rubber" sheet for gasketing,  or as most common binder material in
                              compressed asbestos sheet.   Suitable for hot and cold water, air, steam,
                              some mild acids.   An all  rubber  SBR sheet  is generally not recommended for
                              oils, solvents nor in aggressive type applications, i.e., ketones,
                              esters,  etc.

 Heoprene           CR         Excellent oil resistance;  low permeability to gases; suited for nonaromatic
                              gasoline and petroleum solvents;  highly resistant to ozone, sunlight,
                              weather, aging.   Will not  propagate flame.- Used widely in automotive,
                              aircraft, refrigerant type requirements.

                              A more expensive elastomer than  SBR.  Limited resistance to chlorinated
                              and  aromatic solvents such as carbon tetrachloride, benzol, lacquer solvents.

 Nitrile or        NBR        Superior to Neoprene in resistance to oils and solvents, aromatic and
 BUNA-N                       aliphatic hydrocarbons, animal fats, carbon tetrachloride, lacquer solvents.
                              Has  higher temperature resistance than SBR or Neoprene.

                              Limited  resistance against amines, ketones, esters, ethers and some organic
                              acids.

 Natural or        NR         Primarily employed as gasketing  in all rubber sheet form.  Properties:
 Synthetic          IR         exceptional elongation; excellent tear strength; good wear resistance; low
 Natural                      permanent set;  recovers well; resists most inorganic salts, ammonia, mild
                              acids and alkalies.

                              Has  poor resistance to oils  and  solvents and many chemicals and not recom-
                              mended where exposure to ozone,  oxygen or  sunlight.

 Sillcone           SI         Outstanding elastomer for  extremely high and low temperatures  (-160°F to
                              400°F);  excellent resistance to  oxidation, ozone, sunlight, heat aging.
                              Has  fair resistance to oil and gasoline but poor resistance to aliphatic
                              and  aromatic hydrocarbons.   Ordinarily furnished In rubber sheet form only.

Fluorocarbon      CFM         Excellent  resistance  to acids, aliphatic and aromatic hydrocarbons, oils,
                  FVSI        gasoline  and many corrosive  industrial applications.  High temperature
                  FPM   '      limits similar to silicone, but limited in cold applications below - 40°F.
                              Exhibits  very low permeability to  gases.   Ordinarily furnished in rubber
                              sheet  form only.

-------
                                                 TABLE 10.   ELASTOMER  COMPARISON CHART'
Oi
Common or
trade name
Natural

Synthetic
Natural
Neoprene
SBR
NBR (nitrile)

Butyl

Chlorobutyl

Butadiene

Thiokol
BPR
EPDM

Hypalon

Silicone
Urethane

Viton

Acrylics
Hydrin
Chemical
designation
Natural
Polyisoprene
Synthetic
Polyisoprene
Chloroprene
Styrene- Butadiene
Acrylonitrile
Butadiene
Isobutylene
Isoprene
Chloroisobutylene
Isoprene
Polybutadiene
Stereo-specific
Poly alky lenesul fide
Ethylene-Propylene
Ethylene-
Propylenediene
Chlorosulfonated
Polyethylene
Polydlmethylsiloxane
Polyester
Urethanes
Fluorinated
Hydrocarbon
Polyacrylate
Epichlorohydrin
Heat
resist.
5

5

4
5
4

3

3

5

4
2
3

3

2
5

1

2
3
Oil
resist.
5

5

3
5
2

4

4

4

1
5
5

2

5
2

2

3
1
Ketone/
ester
resist.
3

3

5
3
4

2

2

3

1
2
2

4

4
3

5

5
3
Ozone
resist.
5

5

3
5
4

2

2

5

2
1
1

2

1
2

2

5
1
Low tem-
perature
resist.
4

4

4
4
4

4

4

4

4
3
3

4

1
2

5

5
2
Abrasion
resist.
2

2

2
3
3

2

3

2

4
3
2

3

5
1

3

3
2
Flame
resist.
5

5

1
5
5

5

4

5

5
5
5

2

5
4

2

5
4
Gas
perm.
4

4

2
3
3

1

1

3

2
3
3

1

5
3

2

3
1
          "Numerically rated from 1 to 5 Indicating comparative suitability for a given property; i.e.,  "l"-most resistant,
           "5''-least resistant.

-------
                TABLE 11.  EFFECTS OF NUCLEAR RADIATION ON RUBBER
Property effected


NR
SBR
NBR
CR OR GR
Tensile
strength
retention
3
2
1 best
4
Resistance to
decrease in
elongation
1 best
2
3
4
Retention
of elastic
modulus
1 best
2
3
4
Retention
of dynamic
modulus
1 best
2
3
4
Resistance
to
abrasion
3
2
1 best
4
 The numbers in this chart are numerically rated from 1 to 4 indicating
 comparative suitability for a given priority; i.e., "1" Best.

Note:  NR - Natural Rubber
       SBR - Styrene Butadiene Rubber
       NBR - Nitrile Butadiene Rubber
       CR or GR - Chloroprene Rubber

Ref:  W.J. Born
      B.J. Goodrich

-------
Ul
                    BOLT
                    LOAD
                                                 HYDROSTATIC
                                                 END  FORCE
                                                 GASKET
BLOW  OUT PRESSURE
                          Figure 1.  Static forces acting upon a gasket.

-------
Ul
JL  Ji. JL
 FLAT FACE  MALE 8 FEMALE, LG MALE 8 FEMALE, SM
JL  JL JL
 RAIS€D FACE TONGUE - 8 - GROOVE , LG TONGUE-8 - GROOVE, SM
JLJLJL
METAL-TO-METAL  METAL-TO•METAL RING-GASKET JOINT
         Figure 2. Flange facing types.

-------
          casting to a lapped finish - also see Figure 3) and the
          number and spacing of the bolts.

     As the bolts are tightened, the gasket is compressed and flows into the
surface imperfections so that no pathway for leakage remains.  Only the
surface does the actual sealing.  The body of the gasket provides its
elastic, resilient properties (density is critical to the flow-through of
fluids).  As fluid contacts the inner edges of the gasket, in many cases
the gasket will swell - increasing its sealing properties; although too
much swell signals degradation of the material itself.  One final note.
The thinner the gasket, the better.  But with thin gaskets the better the
flange surface finish must be, and the better the finish, the higher the cost
of manufacture.  Normal gasket thicknesses range from 1/32" to 1/8" with 1/16"
being the most popular.

     In summation it appears that in the gasketing industry materials do
exist that can replace asbestos.  It is also apparent that standard sheet
materials have been overlooked in many applications.  Compressed asbestos
sheet gasketing use can be immediately curtailed by applying one of the
aforementioned materials.  This can be done with little added expense to the
customer unless the application is over 500°F.  Graphite sheet metal gaskets
can replace asbestos over 500°F but their cost will constitute a major
expenditure for plant maintenance.  It is the 500°F to 1000°F area where
gasketing manufacturers are searching for cost effective substitutes.
                                     56

-------
        CONCENTRIC-SERRATED
            PHONOGRAPHIC
Figure 3.   Types of surface finish.
                 57

-------
                        DISCUSSION ON GASKETS AND PACKINGS

QUESTION  (Mr. Castleman):  I would like to know if you have some data on
          the amount of exposure an individual can get, trying to forcibly
          remove some of  these gasket and packing materials?

ANSWER    (Mr. Koehler):  Green Tweed does not have that particular
          information.  I am sure it is available from OSHA.  It is not
          particularly high.  Based on our experience that the amount of
          fiber coming off of a gasket on a flange, as it is being scraped,
          probably does not create much of a health hazard.  This is because
          in a wet, saturated area, the fibers are contained.  If the binders
          are burned out  and the fibers are fairly loose, it can create some-
          what of a hazard.  Today, you will find most plants taking
          extensive precautions with masks and so forth, and roping areas
          off when they have to deal with that type of problem.
                                      58

-------
               ASBESTOS  IN PLASTICS:   LOOKING FOR ALTERNATIVES

                                      by

                              Mr.  Matthew Naitove
                         Plastics  Technology Magazine
                              New  York, New York



                                   ABSTRACT

    Asbestos  has been used as a reinforcing agent in a variety of plastics, most
    notably phenolic molding compounds, vinyl asbestos floor tile, and polyester
    autobody  putties.  In  each of these areas,  material suppliers and plastic
    product manufacturers  have been  looking for alternatives to asbestos, with
    varying degrees of success.  This paper will summarize where asbestos is being
    used in plastic and what efforts are being  made to replace it.



ASBESTOS IN  PLASTICS: LOOKING FOR ALTERNATIVES

     Asbestos has  long been  considered from a technical and economic point of
view to be a valuable reinforcer/filler for plastics.   However, in recent
years, the pressure of government health regulations and of a  strongly neg-
ative public image that  has  come  about with wider recognition  of the hazards
of using this material have  tended  to discourage asbestos use  in all but a
few remaining plastics applications.   Given industry's successful efforts
to develop cost-effective substitutes for asbestos, as well as recently
renewed regulatory initiatives by agencies such as EPA and CPSC, asbestos
definitely appears to be on  the way out of plastics, though it may take
some time before its disappearance  is complete.

WHY AND WHERE ASBESTOS HAS BEEN USED IN PLASTICS

     The most important  functions of asbestos in plastics include enhancement
of thermal and mechanical properties, such as heat resistance, stiffness,  dimen-
sional stability and impact  strength, as well as improving processability
through flow control and thixotropy, plus improving economics  as a result
of resin extension.   (Table  1 shows some of the effects of asbestos  on phy-
ical properties of plastics.)

     Because of those desirable properties, asbestos has traditionally been
used in a wide variety of plastics resins—including phenolic, vinyl,  epoxy,
unsaturated  polyester, urea, diallyl phthalate, polypropylene, nylon and

                                       59

-------
           TABLE 1.  TYPICAL CHANGES IN RESIN PROPERTIES WITH
                     ASBESTOS REINFORCEMENT3
Material
ABS
Nylon 6
Phenolic
Polyethylene
Polyphenylene
sulfide
Polypropylene
Polystyrene

Flexural
modulus
+130
+170
+120
+320
+60
+360
+110
%
Flexural
strength
-20
+100
+50
+30
+100
-
+5.0
change
Tensile
strength
-5
+85
-
+20
+10
-4
+20

Impact
notched
izod
-60
+20
+5
0
+100
+125
-40

HDT,
°F
+16
+200
-
+72
+35
+25
+18
gt
 Optimum reinforcement usually requires 20 to 40 percent short fiber
 asbestos.

Source:  "Asbestos" by Robert E. Byrne, Jr., Union Carbide Corp.
         brochure, reprinted by permission from the Modern Plastics
         Encyclopedia, McGraw-Hill Inc.
                                    60

-------
thermoplastic polyester (PBT).   Applications have ranged from rocket parts
in military/aerospace applications to automotive brake and transmission
components, floor tiles, engine housings, bins and containers, and a variety
of coatings, adhesives, caulks, sealants and patching compounds.

     This paper will concentrate on two areas that have dominated asbestos
use in plastics:  phenolic molding compounds and vinyl-asbestos floor tile
(VAT).  In phenolics, asbestos  has been all but eliminated over the past
eight years; in VAT, the transition away from asbestos appears to be just
beginning.  Virtually all other asbestos uses in plastics are believed to
be extinct, though the picture is somewhat unclear in the area of polyester
auto body fillers.

     It may be noted that virtually all asbestos use in plastics  involves
chrysotile asbestos.  Some anthophyllite was imported from Finland in the
past, but has since become unavailable.

ASBESTOS SUBSTITUTES

     Asbestos used in plastics generally costs in the range of 5-40c/lb.  A
variety of naturally occurring mineral products in the same price range have
proved to be cost-effective asbestos replacements, including mica, clay talc,
clay, and wollastonite.  Two of these products that are rapidly expanding their
roles in plastics filling and reinforcement are mica and wollastonite.

     Mica comes in several mineral forms; however, all of them consist of
plate-like particles, which can be supplied commercially in a range of sizes
and ratios of platelet thickness to diameter.

     Wollastonite is a naturally occurring calcium silicate of fibrous or
needle-like shape.  Typical particle diameter is 3.5 microns and typical
aspect ratio (length/diameter)  ranges from 3:1 to 20:1.  It costs 3-6
-------
    TABLE 2.  PMF VERSUS ASBESTOS IN GENERAL-PURPOSE PHENOLIC3
Filler
Wt. %
Flex. Str. , 10 3 psi
Flex. Mod., 10 5 psi
Tens. Str. , 103 psi
Tens. Mod. , 10s psi
Notched Izod Impact
Str., ft-lb/in.
Volume Resistivity.,
10 ai ohm-cm
UL94 Flammability
(1/8 in.)
None
-
10.4
6.75
7.52
4.53
0.18
1.5
V-0
PMF
33
8.8
7.98
6.62
6.01
0.23
0.7
V-0
STb
PMF
33
12.6
10.87
8.78
5.96
0.26
1.5
V-0
Asbestos
40?
9.1
10.55
5.01
4.93
0.25
0.03
V-0
a
 Data supplied by Jim Walter Resources.

 Surface-treated.
Q
 Commercial compound.


Source:  Plastics Technology, September 1977.
                               62

-------
      TABLE  3.   PROPERTIES OF PMF-FILLED POLYMERS
Resin/FMF Z
G-P Phenolicb
0
33
33STC
50
50ST
HIPSd
0
33
50
Acetale
0
20
33
G-P PPf
0
33
50
PBT8
0 Dry
0 Wet"
33 Dry
33 Wet
33ST Dry
33ST Wet
50 Dry
50ST Dry
Nylon 661
0 Dry
0 Wet
33 Dry
33 Wet
33ST Dry
33ST Wet
Nylon 612^
0 Dry
0 Wet
33 Dry
33 Wet
33ST Dry
33ST Wet
Tens,
str.,
10s psi

-
-
-
-
-

3.9
4.4
4.1

7.6
6.9
6.2

4.9
4.5
4.1

7.3
7.0
7.8
4.6
9.5
8.5
8.2
10.8

10.3
6.9
9.3
5.5
12.7
8.7

8.6
7.3
7.3
6.0
10.8
9.0
Flex,
str.,
10 psi

13.1
9.2
13.4
8.7
12.4

_
-
-


-
-

-
-


9.5
8.3
11.8
8.7
14.5
13.2
11.9
17.2

11.4
5.9
14.7
8.9
17.7
11.4

9.4
6.3
12.4
8.7
15.0
11.2
Flex,
mod. ,
10s psi

6.62
8.23
11.58
9.38
15.55

2.97
7.50
12.00

2.80
5.50
16.00

1.56
5.50
8.10

3.30
2.83
8.15
6.45
7.84
6.02
12.80
12.70

2.04
1.80
7.80
4.30
7.30
4.30

2.98
2.12
6.63
4.33
6.42
4.67
Notched
Izod,
ft-lb/in.

0.13
0.25
0.24
0.28
0.27

1.29
0.58
0.38

1.32
0.55
0.56

0.45
0.63
0.69

0.34
0.46
0.47
0.31
0.51
0.47
0.57
0.53

0.88
1.85
0.57
0.90
0.59
1.20

0.32
0.45
0.41
0.59
0.35
0.54
Heat-distortion
temp. , F
66 psi

-
-
-
_
-

181
196
200

308
317
-

236
266
268

-

-
-
-

-
-
-
is A jSlcc
-"
-
-
-
-

-
_
386
383
386
383
264 psi

-
-

-
-

_
-
-

_
-
278

-
_
-

165
-
359
-
365
_
394
394

360
_
394
-
400
-

217
200
329
324
322
328
 Avg.  aspect ratio of PMF varies  from 40 to 60 for the different polymers  tested,
 though this reportedly affects the data little.
''Durez 12763.
£
 Surface treated.
dShell-324.
eCelanese M-90.
fShell P-520.
8Celanese J-105.
 water conditioning:  16-hr soak  of molded specimen at 122 F.
ThiPont Zytel 101.
^DuPont Zytel 151 L.
Source:  Plastics Technology.,  April 1977.

                                63

-------
      Still  another synthetic product which has  become  important  for asbestos
 is  glass fiber.   It is being used in some new asbestos-free phenolics  (see
 below),  and development of new sizes and types  of glass  fiber  are expected
 to  increase its  utility in this area, according to one phenolic  supplier.
 One potential drawback to glass fiber, however, is that  it can significantly
 increase the cost of a plastic compound relative to asbestos,  though this
 need not always  be the case.  Although glass fiber is  available  in many forms,
 some typical grades used in plastics are priced in the range of  60-70£/lb.

      One more potential asbestos replacement is presently still  in the experi-
 mental stages.   Franklin Fiber is a crystalline calcium  sulfate  microfiber
 with a diameter  of 4-6 microns and aspect ratio around 100:1.  It's produced
 in  pilot-plant quantities by CertainTeed Products Corporation, Elverson, PA.,
 and costs 10-15C/lb.  The product is slightly water soluble, and company
 sources  say that it is made from a non-hazardous material and  does not tend
 to  remain in the body if ingested.

      It  should be noted that a considerable amount of  research is being devoted
 to  increasing the utility of asbestos-replacement products in  plastics by
 treating them with silanes or other coupling agents that promote a chemical
 bond between the filler and the plastic matrix.  Use of  such surface treatments
 tends to improve both the processability and ultimate  mechanical properties
 of  filled and reinforced compounds.

      Because of  the above developments, asbestos*  future in plastics is in
 doubt.   Table 4  shows projections for total asbestos use in plastics,  one
 set of figures dating from 1974 and one set prepared in  1980.  In 1974, the
 average  growth rate projected was 9%/yr; in fact,  it has turned  out to be
 more like 7%.  For the future, the latest projection is  for 4.5%/yr growth,
 though even this is termed "optimistic" by the  source  of these figures.  The
 remaining plastics market for asbestos is VAT,  whose market curve reportedly
 appears  flat in  the future,  and will probably decline  as asbestos substitutes
 are found (see below).

 REPLACING ASBESTOS IN PHENOLICS

      About  six years ago,  according to one major phenolic producer, approxi-
mately 70%  of  all molded phenolic parts contained from 1% to 30% by weight
 asbestos.   At  one time,  250-million Ib of phenolic compounds reportedly
 contained asbestos;  today,  that figure is said  to be 50-million  Ib out of
a total market of 300-million Ib.

      Asbestos-filled phenolics have been used in a number of applications
where heat  resistance is required, including automobile  brake  and transmission
components,  electrical parts,  pot handles,  and  various knobs and other com-
ponents of  large and small appliances, such as  clothes washers and dryers,
dishwashers, refrigerators,  portable heaters, popcorn  poppers  and broilers.
                                      64

-------
                    TABLE 4.   ASBESTOS USAGE IN PLASTICS
           1974 Market analysis (million Ib)
                                                        Avg.  annual
     1971      1973      1974      1976      1984       increase  '74-'84

      350       405       441       523      1042              9%
           1980 Market analysis (million Ib)
                                                    Avg.  annual
          1976      1980      1985      1990      increase  '80-'90

           440	518	645	803           4.5%

     Source:  Business Communications Co.,  Stamford,  Connecticut.


     In 1972, General Electric Company's Plastics Division  was the  first major
phenolic compound supplier to announce that it was completely eliminating all
use of asbestos.  In 1976, another major, Durez Division of Hooker  Chemicals &
Plastics Corporation said it would do the same.  The  company finally completed
the transition in 1979.  Fiberite Corporation, which  was at one time a small
factor in asbestos-filled phenolics, also eliminated  asbestos use several years
ago.

     Only recently has it become apparent that all remaining producers of
phenolic molding compounds intend to pursue a thorough phase-out of asbestos,
which they hope to accomplish by the end of 1980.  Rogers Corporation, Reich-
hold Chemicals, Plastics Engineering Company, and Valite Division of Valentine
Sugars, Inc. all now intend to discontinue  using asbestos-filled grades.  Only
one smaller producer, Resinoid Engineering  Corporation has  said that it has
no plans at the moment to drop asbestos; rather, the  company appears to be
taking a "wait-and-see" attitude regarding  new proposed government  regulations.
In addition, a very minor amount of asbestos-filled phenolic is being imported
from Canada.

     It has taken phenolic suppliers several years of continuous evolutionary
development to arrive at a full line of asbestos replacement.  At first,
there was considerable customer resistance  to the new products while asbestos
grades were still available, but this customer resistance seems to have been
largely overcome.  To quote a spokesman for one major phenolic supplier;
"It was a product-by-product change, using  a variety of materials to develop
the same processability and end-product properties as those provided-by
asbestos.  The transition was difficult. At one time, 90 percent of our
phenolic compounds contained some asbestos—today we haven't got a pound  on
the premises."
                                     65

-------
      Although non-asbestos formulations are proprietary,  and probably contain
 mixtures of fillers,  products such as clay, talc,  wollastonite,  glass fiber
 and Processed Mineral Fiber are all said to have been used as asbestos re-
 placements.  Mica has also been evaluated in this  application, but with lim-
 ited success.  Although mica reportedly builds stiffness  much more than
 equivalent loadings of asbestos, experiments reportedly showed that mica-
 filled phenolics cannot be exposed to elevated temperatures for  long  periods
 without blister formation, according to sources at a mica producer, Marietta
 Resources International.  However, this company reports that better property
 retention is exhibited for phenolic samples containing finer grades of mica.

      Today, it appears that some, if not yet all,  phenolic suppliers  have
 been able to replace asbestos across the board with phenolic compounds that
 exhibit nearly identical properties (90-98% as good, according to one supplier)
 at  nearly identical cost.   (See Table 5.)  In some cases, electrical  properties
 and surface appearance are said to have been improved by  replacing asbestos.
 There are also reports that some asbestos-free phenolic compounds flow better
 for easier processing.

      But there are also some trade-offs, however.   In flame resistance,  an
 asbestos-filled grade can receive an Underwriters  Laboratories UL 94V-0
 rating at 0.040 in.  thickness,  while a non-asbestos grade may have to be 0.060
 in.  thick to obtain the same flammability rating.   To quote a major phenolic
 supplier, "We've pretty much closed our books on asbestos.   We've survived
 the transition in good fashion, but in our replacement products  we have
 sacrificed long-term heat  resistance to some degree."  There seems to be
 some difference of opinion in industry as to whether asbestos-free phenolics
 do  or do not provide  the same degree of long-term  heat resistance.  Some
 suppliers say the heat resistance (retention of properties at elevated
 temperature) of newer asbestos-free grades is more than adequate.  But for
 the very highest performance materials, confidence in asbestos replacements
 may still be less than absolute.

      Also,  it should  be noted that replacement of  short-fiber asbestos has
 proved easier than finding substitutes for long-fiber asbestos,  which is
 used in phenolics for high impact strength.   Long  glass fibers reportedly
 can  provide the same  degree of  impact stength, but may cost as much as 40%
 more than long asbestos fibers.   Long glass may also have the disadvantage
 for  the user in creating more machine wear than does asbestos.

ASBESTOS IN VINYL FLOOR TILE

     One asbestos  supplier estimates that,  at one  time, as  much  as 200-million
pounds  of asbestos was  used in  vinyl-asbestos floor tile.   This  source estimates
that the  figure may be  slightly less now,  owing to competition with VAT from
synthetic carpeting materials and non-asbestos containing types  of vinyl
flooring.  VAT  generally contains only 10-15% by weight of  asbestos.   A very
short-fiber asbestos  is  used, costing about  5
-------
                                  TABLE 5.  GLASS FIBER VERSUS ASBESTOS IN PHENOLICS
a*
Grade
Filler
Specific Gravity
Tensile Strength, psi
Flexural Strength, psia
Flexural Modulus,
million psi
Compressive Strength,
psi
Deflection
Temperature , °F
Dielectric Strength,
V/mil Short Time
Step by Step
RX862
Glass
1.88
6,500
12,0007
14,000
2.3
28,000
500+/
550
300
250
RX865
Glass
1.88
7,500
15 ,000/
17,000
2.5
33,000
550+/
550+
300
250
RX866D
Glass
1.94
6,000
11,500
2.5
28,000
550+/
550+
290
220
RX867
Glass
1.71
6,000
11,500
1.8
27,000
450+/
500+
230
180
RX867D
Glass
1.78
6,000
11,500
2.0
28,000
500+/
550+

RX462
Asbestos
•' ' C
1.79.
6,000
12,000
2.0
24,000
500+
125
100
RX466
Asbestos
..V
« '
1.70
6,500
11,000
1.8
30,000
500+
150
100
RX468
Asbestos
1.72 ..
6,000
10,000
1.8
26,000
450
150
100
    Compression molded/transfer molded.
     As molded/post baked.
    Source:  Rogers Corp., Rogers, Connecticut.

-------
     Recent conversations with two VAT producers  (some refused to discuss the
subject) indicated that both are working actively to either replace asbestos
with something else or perhaps to develop a new flooring product based on
an entirely different plastic that does not require filler.  Also, one pro-
ducer said it had been able to sharply reduce the asbestos content in some
of its current products, but would not explain how.

     One of the two VAT producers interviewed said it hopes to be able to phase
out asbestos in the next two years, the main reason for doing so being the
bad name asbestos has acquired—consumers are becoming afraid of it anywhere.
According to this supplier, all VAT producers are working to eliminate
asbestos.  "Asbestos is dead," he said.

ASBESTOS IN OTHER PLASTIC PRODUCTS

     Numerous miscellaneous uses of asbestos in plastics have appeared over
the years, and some were once thought to be quite promising growth areas,
but all are thought to be defunct today.  These include nylon and polypropylene
auto and appliance parts (asbestos has since been replaced by glass fiber,
mica and talc), vinyl plastisol coatings and sealants, epoxy coatings and
roofing compounds, and polyester premixes for molding auto and tractor parts,
engine housings and bins and containers.  In one application where asbestos
has been used, polyester auto body putties, it's not entirely clear whether
it may still be used to any extent.  Spokesmen for the Autobody Filler
Manufacturers Association (AFMA), headquartered in Chicago, assert that its
member companies do not use asbestos but also say that some non-affiliated
firms may do so.  Platy talc is the approved filler, says AFMA.  At least
some sources in that industry believe that there is use of asbestos or
asbestos-like materials (perhaps as a contaminant in some talcs) in some
body putties, but this could not be confirmed directly.

ACKNOWLEDGMENT

     I would like to thank my associate, Assistant Editor Carl Kirkland,
for his invaluable assistance in researching this topic.
                                      68

-------
                    DISCUSSION ON PLASTICS AND FLOORING
QUESTION  (Mr. Koehler):  For my own edification, I'd like to know if all
          plastic products that are put out for consumer use today contain
          warning labels?

ANSWER    (Mr. Naitove):  I am not aware of any consumer product made of
          plastic containing asbestos that has a warning label.  I don't
          believe such a thing exists.

ANSWER    (Chairman Guimond):  I have seen a few manufacturers put identi-
          fiers on tile and a few other products, but that is all.
                                      69

-------
                   SINGLE-PLY ROOFING AS A  SUBSTITUTE  FOR
                            ASBESTOS ROOFING FELT

                                     by

                             Mr. David E. Bailie
                            Koppers Company, Inc.
                          Pittsburgh, Pennsylvania
                                   ABSTRACT

    Asbestos has  served Industry and consumers in many ways.  In the roofing in-
    dustry, it has solved a problem and created another.  The rapid changes now
    taking place  in the roofing industry have presented adequate alternatives to
    the use of asbestos-containing roofing felt.
     Asbestos has served industry and  consumers  in many ways.   In the roofing
industry it has solved a problem and created  another.

     Some of you may not be  familiar with the construction of a built-up
roof, so I would like to give you a quick course on how a roof is usually
constructed.

     A typical built-up roof is constructed by alternating layers of bitumen
and felt; the bitumen being  either asphalt or coal tar, and the felt being
organic, asbestos, or most recently, glass.

     Organic felt is in greater use, and at one  time,  was produced with a
high rag content.  However,  economics  and lack of supply has caused the
producers of organic felt to go to a high paper  content with a small amount
of wood fiber.  Dry felt is  run through a saturator that allows the dry felt
to soak up the bitumen saturant close  to a point of saturation.

     The bitumen used in built-up roofing is  either asphalt or coal tar.
Asphalt is a derivative of petroleum and is available with various softening
points to suit the specific  needs of the roofing contractor.  Coal tar is
derived by the destructive distillation of coal, better understood as the
production of coke used for  making steel.  Both  bitumens require heat to
cause the bitumen to be fluid.
                                       71

-------
      After the roof deck is in place,  insulation is attached to  the  deck by
 means of mechanical fasteners or a hot adhesive.   The emphasis placed on con-
 serving energy has increased the use of insulation and many times  two layers
 of insulation are applied.   The felt laying begins by mopping on a prescribed
 amount of bitumen into which the felt is embedded.   The application  progresses
 from one side of the roof to the other, laying the felt in shingle-like
 fashion.  When a gravel surface is required, a flood coat of bitumen is  poured
 on the top felt and gravel is embedded while the bitumen is still  hot.

      Built-up roofing is very labor intensive.   Modern practice  utilizes
 mechanical equipment to speed installation.  Mechanical insulation fasteners
 are driven into the insulation and deck by a drill-like device.  The bitumen
 is laid down with a spreader instead of a hand mop, and the felt is  rolled in
 behind it.   On some jobs, the felt is contained on the same piece  of equip-
 ment.   The top pour of bitumen is also laid down with this piece of  equipment,
 and when gravel is required, a gravel buggy is used to lay the gravel.

      The success and longevity of the roof is dependent upon the homogeneous
 formation of the layered construction, and you should now understand why
 this type of roofing is called built-up roofing.

      A built-up roof is analogous to plywood in that the layers  of a roof have
 little strength individually.  A number 15 organic felt, for example, has aver-
 age breaking strength of 30 Ibs. in its longitudinal direction and.15 Ibs. in
 the transverse direction, and- can easily be torn.   When the felts  are laminated
 with bitumen, however, the strength is substantially increased.  The strength
 of a built-up roof is important because of the stress induced by structural
 movement and temperature fluctuations.

      The degradation or weathering of a organic felt occurs when it  becomes
 exposed to  the atmosphere.   The absorption and subsequent drying of  the
 organic felt causes it to break down and eventually blow away.   The  ability
 of organic  felts to absorb moisture creates other problems for a roof.   It
 was these problems that opened the door for the use of asbestos  felts in
 the roofing industry.

     Asbestos roofing felt  became the  new kid on the block.   A better roofing
 felt.   One  that did not absorb water and rot away.   A roofing felt that  had
 better fire resistance.   Indeed, a premium roofing felt to produce a premium
 roof.   And,  I might add,  at a premium price.   Currently, asbestos  felt is
 priced at approximately twice the price of organic felt.

     Asbestos felt entered  the roofing industry as a substitute  for  organic
 felt primarily for roofs  that had a smooth surface, that is, without gravel
 on  the surface.   Asbestos offered a distinct advantage on a' smooth surface
 roof because this type of roof was more susceptable to degradation,  and
 asbestos  felt  would not deteriorate as would an organic felt when  the top
 coating of  asphalt weathered and allowed moisture  to penetrate.  The use of
 asbestos  felt  spread to other roofing  applications as the advantages of
 asbestos  felt  were broadcast.   There is a single  law that applies  to every-
 thing  in  existence —  Murphy's  Law.  As it sometimes occurs with products that
offer  advantages,  there are disadvantages as well.   Sometimes the  disadvantages

                                       72

-------
do not appear until late in the game.   Such was the case with asbestos felt.
Along with the high price of asbestos  felts, we have found  that  asbestos
felts are lacking in breaking strength.  When  tested as  per the  same ASTM
(American Society for Testing and Materials) method used to test organic  felt,
asbestos possesses 1/3 less breaking strength  than  that  of  organic  felt.   Con-
sequently, the industry has experienced  a higher rate of splitting  roofs  when
asbestos felts were used to build up the roof.

     The use of asbestos felt for roofing has  greatly diminished.   There  are
only two producers of such felt in the U.S.  There  are viable alternatives.
One such alternative is glass felts.  The other is  a single-ply  roofing
system.

     Although there have been single-ply systems existing in this country for
15-20 years, they did not blossom until  the early seventies.  At the present
time, the market is flooded with various single-ply systems.  However, all of
them can be categorized into two groups  - modified  bitumen  or polymeric systems.
Within those two groups lies a real variety.

     Modified bitumens include systems in which the bitumen has  been modified
in different ways.  Some are reinforced, others are not. Some are  adhered
with hot adhesive, others with a cold  adhesive.  And there  are systems that
are not adhered at all, but instead are held down with heavy ballast.

     The polymeric systems have similarities to the modified bitumen  systems
in that they contain different polymers. Also, some are reinforced while
others are not.  In addition, polymeric systems can also be loose-laid or
adhered.  Polymeric systems include EPDM (Ethylene  Propylene Diene  Monomer),
Butyl, Neoprene, PVC (Polyvinylchloride), CPE  (Chlorosulfonated  Polyethylene),
and PIB (Polyisobutylene).

     There simply is not enough time to delve  into  the makeup of each membrane,
nor am I qualified to adequately describe the  composition of each.   Each system
also has its own procedure for application, and I'll not bore you with that
either.

     Instead, I would like to dwell on the  two generic  methods of application.
Loose-laid and adhered or semi-adhered.

     Adhered systems are those that are held down with an adhesive.  All
polymeric membranes use a cold adhesive, while some modified bitumen membranes
will use hot, and others use cold adhesive.  The application of adhesive  is
achieved simply by rolling, spraying,  brushing, or mopping  the adhesive  onto
the surface to which the membrane is to be applied.  The membrane  is  then
laid in place, overlapping the preceding layer.  The laps are then sealed to
provide a watertight system.

     The semi-adhered systems are applied by first mechanically attaching a
small piece of the membrane  (9-12"  square).  Adhesive is then applied to these
patches which have been placed l'-2' apart.  The membrane  is  then  placed so
that the membrane is adhered only to the patches.  The  membrane is sealed at
the laps in the same manner as the  adhered  systems.

                                      73

-------
     The loose-laid systems are a new concept in the roofing industry.  In my
opinion, it makes a great deal of sense.  This method of application places
the membrane on the deck, insulation, or existing roof loosely, without any
attachment.  The laps are sealed in the usual manner and heavy stone is
placed on top of the membrane to resist wind uplift.  The value of this system
is that the substrate can move underneath without transmitting stress to the
roofing membrane.

     In summary, I've given you a quick course in the construction of a built-
up roof, its components, the entry of asbestos felts, and an alternate to the
use of asbestos roofing felts.

     In closing, I want to add that knowledgable people in the roofing industry
feel that the demise of asbestos roofing felts is imminent and asbestos felts
can, at the present, be substituted with materials of proven performance with
no economic disadvantage.
                                      74

-------
                                 ROOFING FELT

                                      by

                                 Ms.  Nancy Roy
                                GCA Corporation
                            Bedford,  Massachusetts
                                   ABSTRACT

    Asbestos provides dimensional stability,  rot resistance, fire resistance, and
    heat resistance to roofing felt that is impregnated with asphalt.   Commercially
    available substitutes include organic and fiberglass felts.  Alternative pro-
    ducts are compared on the basis of composition, strength, durability, product
    life, cost, and length of time in the marketplace.  Substitutes for asphalt-
    saturated asbestos roofing felt are well-established in the roofing industry.
    Installed costs of asphalt-saturated roofing felts are surprisingly close.
    Labor costs for installation outweigh the costs of materials by a significant
    factor.
INTRODUCTION

     The following  subjects:  roofing felts and nonasbestos  substitute products
Including organic and fiberglass felts, their composition,  special qualities,
cost differentials,  and length of time on the market will be discussed in this
paper.  From this information, conclusions may be drawn as  to the availability
and economic reality of alternatives to asbestos roofing felt.

     Roofing has been a basic need ever since man first built crude shelters
to protect himself  from the weather.  In the past, settlers used sod and
thatched roofs as these materials were cheap and easy  to come by, but they
needed to be replaced at frequent intervals, and often leaked in heavy rain
storms.   At present, home and business owners are offered  a wide variety of
roofing materials from which  to choose, all of which fit various requirements
and contribute desired attributes to satisfy varied roofing needs.

     A basic distinction can be made between roofs belonging mainly  to home-
owners and large roofs on business properties.  Roofers would view the dif-
ference in terms of "minimum slope" for which a roof is  adapted.  Whereas  the
majority of homeowners' roofs are quite sloped, commercial and industrial  roofs
are mainly flat.  Asbestos felt underlay may be used in  both instances,  but
the Industrial or built-up roofs are described here.


                                       75

-------
 In all cases,  the material discussed is  used as  an  underlay  either to other
 common residential roofing systems such  as  asphalt  shingles  or  classic cedar
 shakes where asbestos helps prevent moisture penetration, or to asbestos felt
 layers themselves in industrial built-up roofing.

 ASBESTOS ROOFING FELTS

      Asbestos  fibers are useful in roofing  felts because they provide:

      •    dimensional stability,  and

      •    resistance to rot,  fire, and heat.

 Dimensional stability is particularly important.  Given the  extreme weather
 conditions a roof must face,  such as rapid  heating  and cooling  of the roof
 surface,  cracking may occur which allows water penetration,  particularly in
 damper climates  or in areas where snow accumulates  on the roof  and is then
 subject to periodic melting.   Asbestos roofing is considered by many roofers
 to have an exceedingly long life.3*1*  Rot resistance is of paramount impor-
 tance on flat  or nearly flat  roofs with  poor drainage.  The  fine resistance of
 asbestos felt  provides an extra margin of safety to property owners, and thermal
 resistance enhances roof durability.

      Asbestos  felt sheet is manufactured with varying formulations on con-
 ventional paper-making machines,  then converted  into roofing felt by saturation
 with  asphalt or  coal tar.   Major  United  States companies who have produced
 asbestos roofing felt include:   Johns-Manville Corporation and  Celotex Corpora-
 tion.   Manufacturers often make the felted  sheet at a centrally located site
 and ship this  product to geographically  scattered sites for^saturation.  This
 saves on shipping costs as the unsaturated  felt  weighs less  .   Asbestos roofing
 felt  is typically composed of 85  to 87 percent asbestos fibers, 8 to 12 percent
 cellulose fibers,  and 3 to 5  percent starch binders .  Grade 6  or 7 chrysotile
 fiber imported from Canada is usually used.   Other  materials, such as wet and
 dry strength polymers,  Kraft  fibers,  fibrous glass, and mineral wool are often
 added as  fillers.   The paper  is made in  either single or multilayered grades
 and may have fiberglass filaments or wire strands embedded between paper layers
 for reinforcement.   The felt's thickness or grade and the amount of asphalt
 costing required depend upon  the  product's  intended use.

      In built-up roofing systems,  the most  common type - a hot  roof - often
 involves  the use of asbestos  roofing felt.   Cold roofs, not  requiring the
 application  of hot tar or asphalt,  were  covered  in  the discussion of single-
 ply membrane systems;  only hot roofing systems will be considered here.  They
 involve the  application of several plys  or  layers of roofing felt alternating
with  asphalt or  tar,  often with a top layer of gravel imbedded  in the asphalt.
Layers  used  may  consist of organic,  fiberglass,  or  asbestos  felts.

      Built-up  roofing such as this is commonly prepared at the  job site by
cutting lengths  from product  rolls  to the required  sizes and shapes.  "Built-
up",  as  implied,  refers to the practice  of  layering or building up paper lengths
on  top  of  each other while hoc  roofing tar  is mopped between the layers for
adhesion and/or  additional weather protection, having a sandwich effect.  The
roofing is attached  to  the surface  roof  deck with adhesive tars (which may

                                       76

-------
also contain asbestos) or by nailing If the roof can accept  such treatment.
Built-up roofs can be topped with:

     •  gravel

     •  smooth, or

     •  mineral surfaces.

Gravel and smooth roof tops are similiarly constructed except that smooth-
surface roofs are only lightly mopped with asphalt whereas gravel surfaces are
flooded with asphalt and then covered with aggregrate gravel which generally
serves more for appearance and ballast than for true protection.   In mineral
surface roofs, roofing paper is sealed with weather grade asphalt embedded
with opaque, noncombustible mineral granules giving the builder a choice of
roof colors.  Asbestos roofing felt has an advantage over organic felt here
as it does not require a gravel surface, a feature which makes it easier to
inspect and repair.

     Asbestos felt may also be used as an underlayer for other roofing pro-
ducts, mostly in residential applications.  For this, asbestos roofing paper
is attached to the roof deck, again by tar adhesives or by nailing, then
covered with shingles, cement sheets, or other forms of common roofing.  In-
cluded in this category are: metal roofs, which formerly were often galvanized
steel in corrugated sheets but now are mostly non-rusting aluminum panels;
slate roofs, an old stand-by which is now offered in imitation form offering
the hand-cut slate look at a lower cost; and tile roofs and  wood shakes, both
commonly seen materials used mainly for homeowner applications.   At least
60 percent of asbestos roofing felt is applied during re-roofing jobs while
the remainder is used in new construction.

ALTERNATIVE ROOFING FELTS

     There are two alternatives to asbestos roofing felt other than singly-ply
membrane systems.  These substitute products are organic felt and fiberglass
felt.

     Organic felts have been used in United States built-up roofing systems
for about 25 years.  They are made primarily from cellulosic fibers on paper-
making machines, and, as with all roofing felts, are saturated with coal  tar
or asphalt.  Major manufacturers of organic felts include: Johns-Manville,
Celotex, Bird and Son, Koppers Company, GAF, and CertainTeed Corporation.

     Fiberglass roofing is a newer product, introduced around  1964 by  Owens-
Corning, but only recently enjoying widespread use.  It  is composed of glass
or refractory silicate and a binder.  Owens-Corning, Johns-Manville, and
others produce fiberglass felt; other companies such as  PPG  Industries and
Reichold Chemical Company manufacture the basic.fiberglass strand and  sell
this to the actual paper product manufacturers.   '    .   Three  basic manu-
facturing processes are employed, including the continuous filament  process
used by Owens-Corning, a steam blown process using  shorter fibers,  and a
slurry process similar to the basic paper-making process.

                                     77

-------
      To compare these two products with asbestos felts,  several factors
 must be considered, including:

      •  strength and durability

      •  product life

      •  product cost, and

      •  length of time that the product has been available.

 Although organic felt rates lowest in terms of strength  and  durability,  it  is
 still the most widely used.  The primary reasons are its low cost  and time-
 tested nature; since it has been on the market the longest,  its qualities are
 well known.   Fiberglass products have been praised for exceptional uniformity
 and natural  venting characteristics.  More uniform porosity  of this product
 allows deep  penetration of asphalt leading to improved interply adhesion.

      Fiberglass has the same technical features as asbestos, but requires
 less asphalt saturation.  Both fiberglass and asbestos systems are inorganic
 and, therefore, have better rot resistance and dimensional stability than
 organic systems.

 ECONOMICS

      A comparison of installed unit costs, which may be  more meaningful, still
 shows organic felt to be least expensive, but the prices are now closer.  Or-
 ganic felt averages about $60.00 per installed square, asbestos and fiberglass
 around $70.00, and single-ply membrane at about $100.00.   This is  where  the
 single-ply membrane really shows itself to be more competitive than apparent
 based only on material cost,  because it is not labor intensive and material
 savings (such as tar or asphalt) become evident.   This should make products
 like fiberglass and single-ply membrane systems become even  more competitive
 in  the future.  Industry sources believe that these materials will reduce the
 share of both organic and asbestos felts in the built-up roofing market.

      Lifecycle costs should also be considered: that is  to say, an asbestos
 roof may be  slightly more expensive than an organic roof,  but if the asbestos
 roof is replaced every 20 years while the organic roof must  be replaced  every
 10  years,  the asbestos roof is more economical.  Unfortunately, data on  the
 expected lifetime of the different roofing types  is sparce.   Lifetimes depend
 on  such factors as surface finish (smooth is more susceptible to degradation)
 and whether  coal tar or asphalt is used (coal tar lasts  longer), as well as
 climate and.yearly weather cycles; the roof lifetime is  a difficult parameter
 to  predict.

      A product such as Johns-Manville's Glas Fly  system meets the  200 pounds
 per square inch (at 0°Fahrenheit)  tensile strength preliminary performance
 criteria recommended by the National Bureau of Standards.  This product  re-
 quires  less mopping asphalt than other systems as more asphalt is  impreg-
nated during product manufacture.
                                       78

-------
     Cost is certainly a most important aspect  of  substitute  analysis.   Specific
roofing costs are given in Table 1,  attached.   Two cost  comparisons  are valu-
able:  first, basic roofing material costs for  asbestos,  organic and fiberglass
felts and second, the cost for installed units  of  roof.   Since  rolls come in
different sizes and the number of layers installed on the roof  will  vary de-
pending on the felt used, the basic  unit of comparison employed is the  square
- a one hundred square foot area of  roofing.

     In terms of material cost per completed square,  only organic felt  is
cheaper than asbestos, while asbestos and fiberglass  are nearly equal.   In
general, prices range from around $10.00 a roll for organic,  to about $25.00
per roll for asbestos and fiberglass, and finally  to  about $65.00 for the single
ply membrane system.  Prices differ  from the conference  hand-out figures, in
that, in most cases, they are now lower.  Only  the cost  of asbestos  has gone up.
Asbestos and fiberglass are nearly equal in quality and  durability,  and cost,
which is very close at present, will probably shift to favoring fiberglass in
the near future.

     Since a price comparison of average costs  of  installed roofs only  shows
about a $25 fluctuation between products, one must also  look  at other attri^
butes.  Time-tested qualities and builder experience  together with these cost
findings now become valuable in predicting market  trends.

CONCLUSION

     Organic felts have been marketed longer than  all other roofing  materials
covered, although the single-ply membrane system has  been used  in Europe for
a longer period than its 5-6 year introduction  in  the United  States. Asbestos
felt is also a fairly new product in the roofing industry; however  it had an
advantage that shot production ahead.  In 1968, the American  Society for Test-
ing and Materials issued a recommendation for the  use of asbestos felt  on built-
up roofs which helped asbestos felts quickly penetrate the roofing market.  Now,
competition and health concerns appear to be dulling  this edge.  In 1976 built-
up roofing sales of all types were about 53 million squares.   Organic systems
had about 45 percent of the market,  asbestos felt  25  percent, and fiberglass
felt 10-15 percent.   The remainder  consisted of single  ply and other roofing
systems.  Some companies such as GAF and Nicolet Industries,  have terminated
or cut back their production of asbestos roofing felt.  From telephone surveys
it appears that the use of organic felt is widespread, at least in the North-
eastern United States.  In the West  and Soutwest tile roofs are common.

     A product such as tile roofing, however, is suitable only for pitched  roof
surfaces which are usually residential, as compared to built-up roofs where
asbestos is used.  Tile roofs require little underlay, which likely  increases
their popularity.

     Since only organic felt roofs have been used in the United  States  for  more
than 20 years, it is difficult to draw firm conclusions  concerning  the  long-
term durability of the various roofing systems.  Industry representatives differ
in opinions of superiority between asbestos, fiberglass, and organic felts, with
questions stemming from possible variability in fiberglass felt  quality.  Con-
version of asbestos felt manufacturing lines to the  fiberglass felt mat product

                                      79

-------
requires manufacturing experience and applicator training.  Nevertheless,
fiberglass seems to be quickly gaining on the built-up roofing market.   Problems
with alternative materials such as these are currently being investigated by
manufacturers; many difficulties will be minimized when installers become more
familiar with their use.  If costs become more competitive, as they seem bound
to be with rising asbestos and petroleum product costs, there is every reason to
believe that dependable, cost-competive substitutes are available to replace
asbestos roofing felts.
                       TABLE 1.  ROOFING COSTS
Roofing
felt type
Organic
felt
Asbestos
felt
Fiberglass
felt
Single-ply
membrane
system
Retail cost
per roll ($)
10.00

25.00

25.00

65.00


Installed cost
per square ($)
$50-60

$70

$70

$100


                   Cost includes labor and materials for base
                   sheet plus equal amounts of layers of felt.
                  Source:  Telecon.  D. Bailie, Koppers Company,
                           with N. Roy, GCA Corp./Technology Div.
                           July 11, 1980.
REFERENCES

1.   Time/Life Books.  Roofs and Siding.  Alexandria, VA  1977.

2.   Cogley, D. C., and N. K. Roy, et al.  Asbestos Substitute Performance
     Analysis.  Draft Report.  U.S. Environmental Protection Agency, Office
     of Pesticides and Toxic Substances, Washington, D.C.  March 1980.

3.   Telecon.  McLaughlin, E. Estimator, C and M Roofing, Somerville, MA,
     with D. Ramsay, GCA Corp./Technology Div., August 20, 1979.

4.   Telecon.  Estimator, Matick Roofing Company, Chelsea, MA, with
     D. Ramsay, GCA Corp./Technology Div., August 20, 1979.

5.   Asbestos Industry Draft Profile, Prepared for OPTS, U.S. EPA, June
     1980.  EPA contract No. 68-01-5818.
                                      80

-------
6.   A. D. Little.  Characterization of the U.S.  Asbestos Papers Markets.
     Prepared for the Minister of Industry and  Commence  - Government  of Quebec;
     Final Draft Report to Sores Inc.   (Montreal),  Report C-79231,  1976.

7.   Anonymous.  Manual for Built-Up Roofs.   Published by Johns-Manville Corp.,
     1978

8.   Wright, M.D. et al.   Asbestos Dust Feasibility Assessment  and  Economic
     Impact Analysis of the Proposed Federal Occupational Standard, Part I:
     Technological Feasibility Assessment and Economic Impact Analysis.  U.S.
     Department of Labor, Occupational Safety and Health Adminstration.  Wash-
     ington, D.C.  Contract No. J-9-F-6-0225 Task  2.  September 1978.

9.   Contact with various industry sales persons  by GCA  Corp./Technology Div.,
     1979.

10.  Telecon.  H. Chess,  PPG Industries, Pittsburgh, PA, with S. Bianchetti,
     GCA Corp./Technology Div., June 27, 1980.

11.  Telecon.  Ms. McKinney, Reichold Chemical  Co., Irwindale,  CA,  with
     S. Bianchetti, GCA Corp./Technology Div.,  June 27,  1980.

12.  Telecon.  D. Bailie, Koppers Company, Inc.,  Pittsburgh, PA, with
     N. Roy, GCA Corp./Technology Div., July 9, 1980,

13.  Telecon.  A. Noble,  Assistant Sales Manager, Koppers Company,  Eastern
     Division, West Orange, NJ, with D. Ramsay, GCA Corp./Technology Div.,
     August 30, 1979.

14.  Telecon.  G. Perkins, R-625 Products Marketing Manager,  Owens-Corning
     Company, Toledo, OH, with D. Ramsay, GCA Corp./Technology  Div.,
     August 29, 1979.

15.  Telecon.  Salesman,  Bradco Supply Corporation, Woburn, MA, with
     D. Ramsay, GCA Corp./Technology Division,  August 17, 1979.

16.  Telecon.  D. Bailie, Koppers Company, Pittsburg, PA, with  N. Roy,
     GCA Corp./Technology Div., July 9, 1980.
                                      81

-------
                        DISCUSSION ON ROOFING PRODUCTS

QUESTION   (Mr. Shaimes):  Do you use the same number of plys for a glass fiber.
           inlay as you  use for organic fiber inlay?

ANSWER     (Mr. Bailie):  Right now, I think the industry is trying to reduce
           the number of plys of felt used.  You will find each producer with
           his own various specifications.  Most of the time, you will find the
           same number of plys.  I would not be surprised, in the future, as
           the production of glass felts is firmed up, that the number will be
           reduced; but  as a rule, right now, I think it is most typical to
           find the same number of plys.  The use of a glass base sheet, a very
           heavy glass,  might become more prominent, thereby allowing the num-
           ber of plys to be reduced even further.

QUESTION   (Mr. Castleman):  A couple of questions.  One, do you have any
           problems of irritation or skin reactions from workers handling the
           fiber glass products; and, two, can you tell me the size distribu-
           tion and diameter of the fibers used in the fiber glass product?

ANSWER     (Chairman Guimond):  I think the size question, relative to the fiber
           glass product, will be discussed in the health-related session.  I
           personally do not know which size fibers are used.

ANSWER     (Mr. Bailie):  They will vary by different processing methods.

           Certainly, when you handle fiber glass in its raw form, it can be
           irritative.   However, in fiber glass felts, the felt pretty well
           encapsulates  the glass fiber, so unless you happen to hit the edge
           of the felt where it has been cut, you should have no irritation at
           all.  There is enough asphalt on it to protect you from the glass
           fiber itself.

QUESTION   (Dr. Millette):  I am with the EPA Water Health Effects.  I want
           to make one comment about some work that we are doing on the
           exposure of asbestos to home cisterns from different types of
           roofing material.

          We have not done a lot of work yet, but in one case we looked at
          asbestos cement tiles and found that over a number of years, the
          tiles had deteriorated by the weather.  Therefore a roof that
          collected water for a cistern would contain very high amounts of
          asbestos.  When we looked at several fairly old roofs that used
          the asbestos roofing felt material, we did not find any fibers in
          the drinking water of the cisterns that collected water from these
          types of roofs.   But we did take samples of the roof and dissolved
          it and did find that fibers were present.   But, apparently they
          are well enough encapsulated that they did not come off in large
          numbers into the  drinking water.   The third type of roof was
          asbestos-containing coatings painted onto metal roofs.  At least
          in one case we have found some asbestos fibers in the drinking
          water in that cistern.
                                       82

-------
          You gave a breakdown on the amount of different materials sold in the
          last year or so.  Do you have an estimate on how many residential
          roofs in the United States would have asbestos felt materials in them?

ANSWER    (Mr. Bailie):  I seriously question whether any have asbestos felts
          on them because it is quite unlikely that a roofing contractor would
          use an asbestos asphalt saturated felt underneath shingles when he
          can use an organic felt.
                                     83

-------
                 MILL APPLIED COATINGS FOR  UNDERGROUND PIPELINES

                                        by

                                   Mr. Jack  Wink
                                Bredero Price,  Inc.
                          Fairless Hills, Pennsylvania



                                      ABSTRACT

     The purpose of  this discussion is to cover the fundamental philosophy for the
     selection, application and performance of pipe coatings,  as used for pre=
     vention of the  deterioration of metals buried in earth or submerged in water.

     The basic function of a pipe coating on underground or underwater structures
     ±B to isolate the metal from contact with the surrounding environment.  Metals
     are unstable in these environments and reversion from their commercially pure,
     unstable form to a more stable chemical compound is corrosion.  Pipe coatings
     form the first  line of defense against this corrosion.  Since a properly
     selected and properly applied coating should provide approximately 99 percent
     of the protection required, it is of utmost importance to know the advantages
     and disadvantages of all available coatings.  "The right  coating materials
     properly used will make all other aspects of corrosion control relatively
     easy."1  This coating system will be supplemented with cathodic protection
     to give the necessary overall corrosion control.  Today with the many
     coating systems available, the job of selecting the proper coating
     necessitates careful analysis of the many desired properties for an effective
     pipe coating.
PIPE COATING FUNDAMENTALS

      The purpose  of this discussion is to cover  the fundamental philosophy for
the  selection, application and performance of pipe coatings, as used for
prevention of the deterioration  of metals buried in earth or submerged in
water.

      The basic function of a pipe coating on underground or underwater
structures is to  isolate the metal from contact  with the surrounding environ-
ment.   Metals are unstable in these environments and reversion from their
commercially pure,  unstable form to a more stable chemical compound is
corrosion.  Pipe  coatings form the first line of defense against  this
                                         84

-------
corrosion.  Since a properly selected and properly applied coating should
provide approximately 99 percent of the protection required,  it is of utmost
importance to know the advantages and disadvantages of all available coatings.
"The right coating material properly used will make all other aspects of
corrosion control relatively easy.1"  This coating system will be supplemented
with cathodic protection to give the necessary overall corrosion control.
Today with the many coating systems available, the job of selecting the
proper coating necessitates careful analysis of the many desired properties
for an effective pipe coating.   The National Association of Corrosion
Engineers clearly defines the specific qualities that a pipe  coating should
possess in NACE Standard RP-01-69, Section 5:  Coatings.

     Let us first review the desirable characteristics of a pipe coating:

1.   Effective Electrical Insulator

     Since soil corrosion is an electrochemical process in which an electrical
current flows from the structure to the soil carrying metallic ions with the
flow of current, a pipe coating has to stop this current by effectively
isolating the structure from the environment.

2.   Ease of Application to Pipe

     The coating material must be suitable for the intended service and
properly applied to be effective.  There are many excellent pipe coatings that
require exacting application procedures that are difficult to maintain.  Con-
sistent quality may best be obtained with a coating system that is least
affected by variables.  Coating application specifications and good construction
practices combined with proper inspection contribute to the quality of the
finished coating system.

3.   Applicable to Piping with a Minimum of Defects

     This characteristic correlates with ease of application.  No coating is
perfect, and that is why cathodic protection is required; however, no one
wants to buy a pipe coating that has too many holidays (voids in coating)
even before it leaves the mill.

4.   Good Adhesion to Pipe Surface

     Coating adhesion is important to eliminate water migration between the
metal substrate and the pipe coating.  The coating adhesion assures perman-
ence and ability to withstand handling during installation without losing
effectiveness.

5.   Ability to Resist Development of Holidays with Time

     Once the coating is buried, two areas that may destroy or degrade
coatings are soil stress and environmental contaminants.   Soil stress,
brought about in certain soils that are alternately wet and dry,  creates
                                      85

-------
 tremendous forces that may  split, bog or cause thin areas.  Adhesion, cohesion
 and  tensile strength are  important properties to evaluate in order to mini-
 mize this problem.  The coating's resistance to chemicals, hydrocarbons,
 acidic or alkaline  conditions has to be known in order to evaluate performance
 in known contaminated soils.

 6.    Ability  to Withstand Normal Handling,  Storage and Installation

      The ability of a coating to withstand  damage is a function of its impact,
 abrasion and  ductile properties.  Pipe coatings are subjected to a great deal
 of handling between the time of application to the time of backfill.  While
 precautionary measures of proper handling,  shipping and stockpiling are
 recommended,  the coatings vary in their ability to resist damage.  Outside
 storage requires resistance to ultraviolet  rays and temperature changes.
 These properties must be  known and evaluated to assure proper performance.

 7.    Ability  to Maintain  Substantially Constant Electrical Resistivity
      with Time

      Since corrosion is an  electrochemical  reaction, a coating with a high
 electrical resistance over  the life of the  system is important.  The per-
 centage of initial  resistance drop is not as indicative of the pipe coating
 quality as is the overall level of electrical resistivity.

 8.    Resistance to  Disbonding when under Cathodic Protection

      Since most pipelines will eventually be cathodically protected, it is
 necessary for the coating to be able to withstand cathodic disbondment.  The
 amount of cathodic  protection required is directly proportional to the quality
 and  integrity of the coating.  Considering  interference and stray current
 problems, this becomes a  most important requirement.

      Cathodic protection  does two things to a coating.  First, it has the
 ability to drive water through a coating which would ordinarily resist such
 penetration.  Second, it  may produce hydrogen at the metal surface whenever
 current reaches it  and the  hydrogen in turn will break the bond between the
 coating and the metal surface.  While no coating is completely resistant to
 damage by cathodic  protection, it is very important that we choose a coating
 that will minimize  these  effects.

     The ASTM G8-72 test  for Cathodic Disbonding of Pipeline Coatings,
 commonly known as the salt  crock test, is a method used to measure a
 coating's resistance to damage by cathodic  protection.  An intentional
 holiday is placed in the  coating being evaluated and the sample is immersed
 in a 3 percent salt solution (1% sodium carbonate, 1% sodium sulfate, and 1%
 sodium chloride.)   Then when a negative electrical potential is applied through
 the aqueous salt solution by means of an anode or rectifier, an electrical
 current will  flow through the solution to the bare metal surface as it would
 in actual use.  The sample  is maintained at a constant potential and the
 current drain that  is required to protect the sample is measured periodically.
After a period of 30 to 90  days, the- sample is removed and examined for


                                      86

-------
undercutting or any discontinuities.   These discontinuities are  easily
Identified by an accumulated calcite  deposit around  them.  Relative  resistance
of the coating to cathodic protection is  determined  by  the number  of un-
intentional holidays,  by the amount or increase  in current that  has  been
flowing and by the amount of cathodic disbondment or undercutting  that has
occurred around the intentional holidays.   The difference in  the reaction to
this test by various coatings is sometimes  very  vivid.   In some  cases,
such a quantity of water is driven through  the coating  that the  coating
develops large water blisters all around  the sample.  Then, in other cases,  the
cathodic disbondment around the intentional holiday  is  so great  as to  cause
the entire sample to become disbonded from  the surface.  Then, of  course, some
samples experience very frequent unintentional holidays.  Some coatings,  on
the other hand, exhibit no unintentional  holidays, very little water being
driven through the coating and almost no  cathodic disbondment around the
intentional holiday.3

9.   Ease of Repair

     Recognizing that some damage may occur, as  well as the necessity  of  field
coating the weld area, compatible field materials are required to  make
repairs and complete the coating after welding.  Manufacturers'  recommen-
dations should be followed.  Field condition variables  will influence  your
selection of materials.

     All nine of these properties are necessary  and  it  is  impossible to cite
one as being the most important, as  they  all contribute to a  successful pipe
coating.  However, perhaps we can agree that one property not specifically
listed under this recommended practice has  the most  influence on performance,
and that is resistance to water penetration.  Once  in  its  environment, water
penetration will effect performance  in that absorbed moisture will carry
electrical current through the coating material  and  therefore,  the electrical
resistance will be reduced.  A rather simple test is often used  to determine
water absorption and that is to measure weight  gain  following immersion for
a specific period of time.  This test is  not recommended,  as  the results are
not necessarily valid for evaluation comparison of different  coating systems.
Factors to consider in this method are that some coating materials could be
dissolving ingredients at the same time they are absorbing water.   Therefore,
a net weight increase would not be indicative of water absorption.  The
thickness and the composition of the coating material  would  also be a factor
to consider in this method of evaluating coating systems based on water
absorption.  A more accurate method is the ASTM G9-72  standard method of
test for water penetration into pipeline coatings.   "This method consists of
an immersion-type test where pipe specimens are suspended in an aqueous
electrolyte for the duration of the test period.  Electrical measurements
of coating capacitance and dissipation factor are used to follow  the  water
absorption rate of the test materials."1*

     The following factors should also be considered when selecting a pipe
coating.5
                                      87

-------
     1.   Type of soil or back fill

     2.   Accessibility of pipeline

     3.   Operating temperature of piping

     4.   Ambient temperatures during construction and installation

     5.   Geographical and physical location

     6.   Handling required and storage conditions

     7.   Costs

     Evaluation of pipe coating properties coordinated with the above con-
siderations will assist in the selection process.  Of the above factors,
the most misunderstood one is "costs".  In pipe coating economics as in all
cost analysis, the end has to justify the means.  In other words, the added
cost of coatings and  cathodic protection has to earn its way by paying for
itself through reduced operating  costs and longer life.  "True" protection
costs should not only include initial costs of coating and cathodic protec-
tion but also installation, joint coatings and repairs.6  Field engineering
and facilities to correct possible damage to other underground facilities
that may be damaged by increases  in current requirements may add additional
costs, possibly even  outweighing  the initial costs of the pipe coating.7
Another well known expression "that you get what you pay for" certainly has
application to the purchase of pipe coatings.

     We have defined  the purpose  of a protective coating and have detailed
the desirable properties of an effective pipe coating.  If any one coating
excelled in all these properties, it would be a perfect pipe coating.
Suffice it to say, we are still striving to design the perfect pipe coating.

     How can you best select the  pipe coating to meet your requirements?
Experience has proven a reliable method but how much experience, 20 years?
it has been approximately 23 years since the plastic coatings have become
available and only 5  to 7 years   that present formulations have been on
the market.  Many companies utilize accelerated tests as established by ASTM
to enable them to make a quantitative evaluation of these properties.  You
as a user have to weigh the importance of these properties in light of your
own conditions.

     We will now look at the different coatings available, describe their
properties and then how they are applied.

1.   Enamels

     The bituminous enamels are formulated from coal tar pitches or petroleum
asphalts and have been widely used as protective coatings for over sixty-
five years.  Coal tar and asphalt enamels are available in summer or winter
grades.  These enamels are the corrosion coating; they are combined in various
combinations of glass and/or felt to obtain mechanical strength for handling.
You should also specify that these materials meet requirements such as
National Association of Corrosion Engineers, National Association of Pipe

-------
Coating Applicators, or the American Water Works  Association.   The enamel
coatings have been the workhorse cdatings of the  industry;  and, when properly
selected and applied, can provide efficient, long-life  corrosion  protection.

     Enamel systems may be designed for installation and  use within an
operating temperature range of 30°F to 180°F (-1.1°C to 82°C).  When tempera-
tures fall below 40°F (4.4°C), added precautions  should be  taken  to prevent
cracking and disbonding during field Installation.   Enamels are effected by
ultraviolet rays and should be protected by  kraft paper of  white  wash.   Enamels
are effected by hydrocarbons, and the use of a barrier  coat is  recommended
when known contamination exists.  This coating is available on  all sizes of
pipe.  In recent years, the use of enamels has declined for the following
reasons:8»9

     1.   Reduced number of suppliers,

     2.   Restrictive O.S.H.A., E.P.A., and  F.D.A.  environmental  and
          health standards,

     3.   Increased acceptance of plastic coating materials,  and

     4.   Alternate utilization of raw materials  as a tuel.

     For all pipe coatings, pipe should be ordered  bare,  free of  mill coatings,
to permit the best surface preparation.  Prior to blast cleaning  the pipe is
heated to drive off surface moisture and loosen mill scale.  The  blast
cleaning will use sand or steel shot or grit or a combination of  both to
obtain the desired profile and cleaned surface.  Blasting operations shall
remove all rust, scale and other impurities  from the surface, exposing base
metal over all, which presents a grayish matte appearance between Steel
Structures Painting Council Standard SP-6 and SP-10.  This is equivalent to
NACE Standard TM-01, Visual Standards, between NACE No. 3 and NACE No. 2.

     The blast cleaned surface is primed by brush,  spray or by use of a
priming rag commonly known as a "granny rag."  When the primer has dried
sufficiently, the coating and wrapping is performed by the hot application
of a bituminous coating which is pumped from the coating machine through
what is commonly called a spreader, from which the coating flows in a flood
coat onto the surface of the pipe.  One important factor is to be sure  that
the coating material is melted down properly and brought to application
temperature gradually.  This is accomplished in an agitated kettle.

     Agitation is needed to maintain uniform heat and  to prevent the mineral
fillers  (25 to 35 percent) from settling out.  Settling of the fillers  may
tend to develop what are known as hot spots, or carbon spots on  the bottom
of the kettle.  These small  carbon spots will break down and get  into the
coating material and eventually cause jeeps or holidays  in the line.   Carbon
spots are cathodic  to the metal and will cause the metal to  pit.   Thus,  the
melting  operation and the mechanical  agitators are  of  extreme  importance.10
                                      89

-------
      An asbestos  felt wrapper has  generally been used as the outer wrap but
with  restrictions on asbestos as a carcinogen,  it is being replaced by a
glass wrapper.  Care must be taken in  application of the glass wrap, that it
is  properly encapsulated with enamel to  prevent a wicking action of moisture
from  the environment to the steel.

      Mill wrapping has  many variations in  specifications as to the various
types of bituminous  coating materials  which are applied to a nominal 3/32"
(.24  cm) thickness,  followed by the glass  or asbestos felt or combination
of  both. Multiple coatings of  enamel  are  often applied to build up the total
thickness where greater protection is  required.

      An electrical inspection of the completed  coating should be made in
accordance  with the  procedures  established by NACE  Standard RP-02-74,
Recommended Practice for "High  Voltage Electrical Inspection of Pipeline
Coatings."

      For a  more detailed treatment of  this subject  the ANSI/AWWA C203-78
American National Standard for  Coal-Tar  Protective  Coatings is recommended.

2.    Asphalt Mastic

      Asphalt Mastic  pipe coating is a  dense, mixture of sand, crushed lime-
stone and fiber bound together  with a  select, air blown asphalt.  These
materials are proportioned to secure a maximum  density of approximately
132 pounds  per cubic foot.  This mastic  material is available with various
types of asphalt.  Selection is based  on operating  temperature and climate
conditions  to obtain maximum flexibility and operating characteristics.  This
coating is  a thick,  1/2" to 5/8" (1.27 cm  to 1.6 cm) extruded mastic re-
sulting in  a seamless corrosion coating.

      Extruded asphalt mastic pipe  coating  has been  in use for over fifty
years.   It  is the thickest of the  corrosion coatings and is cost effective
for offshore installations.  Its ability to dissipate heat while providing
a relatively holiday free coating,  has made it  the  most used pipe coating
for pipe type cable  installations.1J>

      Asphalt mastic  systems may be designed for installation and use within
an  operating temperature range  of  40°F to  190°F (4.44°C to 88°C).  Pre-
cautionary measures  should be taken when handling in freezing temperatures.
Whitewash is used  to protect it from ultraviolet rays, and this should be
maintained when in storage.  This  system is not intended for above ground
use or  in hydrocarbon contaminated  soils.  This coating is available on
4-V  to  48"  O.D.  (Optical Density)  (11.4 cm to  122  cm) pipe.

     The application procedure  is  as follows:12

     Prior to blast  cleaning the pipe  is heated to  drive off surface
moisture and loosen mill scale.  The blast cleaning is accomplished by a
combination  of shot  and grit to remove all rust, scale and other impurities
from the surface,   exposing base metal  over all, which presents a grayish

-------
matte appearance between Steel Structures Painting Council Standard SP-6
and SP-10.  (NACE No. 2, NACE No. 3).   Pipe is then spray coated with an
asphalt primer prior to extrusion of the hot mastic mix to the circumference
of the pipe.  This is a continuous extrusion which forms a seamless coating
bonded to the pipe.  Whitewash is applied to reflect the sun's rays and to
facilitate stockpiling.  An electrical inspection of the completed coating
should be made in accordance with the procedures established by NACE Standard
RP-02-74.  Recommended Practice for "High Voltage Electrical Inspection of
Pipeline Coatings."  Holidays are patched and retested.  Patching is
relatively easy, because the mastic is thermoplastic, it is heated and worked
with a trowel to reseal.

3.   Extruded Plastics - Polyethylene and Polypropylene

     The extruded plastic coatings have been available to the industry since
1956 and their growth and acceptance has been remarkable during this period.
Initial problems of stress cracking and shrinkage have been minimized by
better quality and grade of high molecular weight polyethylene resins.  There
are presently two systems available in the United States.  One is an
extruded polyethylene sleeve which is shrunk over a 10 mil asphalt mastic,
and the other is a dual extrusion, where a butyl adhesive is extruded onto
the blast cleaned pipe followed by multiple fused layers of polyethylene.
The latter method utilizes multiple extruders in a proprietary method which
obtains maximum bond with minimum stress.  The sleeve type is available on
1/2" through 24" O.D. (1.3 cm to 61 cm) pipe, while the dual extrusion is
presently available on 2*5" through 103"  (6.35 to 262 cm) pipe.  The operating
temperatures range for polyethylene systems from -40°F to 180°F (-40°C to 82°C)
and for polypropylene it is -5°F to 190°F (-21°C to 88°C).  The polyethylene
systems have been successfully field bent (1.9° per pipe diameter length)
at -40°F  (-40°C).  Swelling may occur in hydrocarbon environments.  Polyeth-
ylene has excellent dielectric strength.  With the proper selection of polyeth-
ylene resins and the addition of 2% percent carbon black, the dual extrusion
system has withstood long term aboveground storage and aboveground use.  An
electrical inspection of the completed coating should be made in accordance
with NACE Standard RP-02-74 Recommended Practice for "High Voltage Electri-
cal Inspection of Pipeline Coatings."

     The application methods are as follows:

     Both methods preheat bare pipe prior to grit blast cleaning to a
commercial blast clean.  With the sleeve type coating, the adhesive
undercoating is applied by flood-coating the hot material over  the pipe
before it passes through an adjustable wiper ring which controls the  thick-
ness.  After the mastic is applied, the pipe passes  through  the center of
the crosshead die where the plastic is water quenched  to shrink it  around
the undercoating and pipe.  Following electrical inspection,  pipe  ends are
trimmed for cut back and the coated pipe is stockpiled.

     In the dual extrusion system, the cleaned pipe  is rotated  at  a cali-
brated rate through the process.  The first of two extruders applies a film
of butyl adhesive of predetermined width and thickness,  fusing the film to


                                     91

-------
the rotating pipe  in  two  layers.  While the butyl is still in a molten state,
high molecular weight polyethylene is applied from the second extruder in
multiple  layers  of a  predetermined thickness, producing a bonded coating
50 to  100 mils thick.  Water quenching, electrical inspection and cut back
is completed prior to stockpiling.

     Polyethylene  systems have been  in use in Europe for approximately fifteen
years  with both  crosshead and side extrusion methods.  In addition to the
butyl  adhesive or  asphalt mastic  adhesive, some systems use a polyethylene
copolymer adhesive.   This system  requires high temperature 200°C (390°F)
heating for application of  the adhesive.13

     For  a more  detailed  treatment of extruded plastic pipe coating systems
the reader is referred to the paper  "Extruded Plastic Pipeline Coatings.11*

4.   Fusion Bonded Thermosetting  Powder Resins

     Fusion bonded powder pipe coatings were first introduced in 1959 and
have been commercially available  since 1961.  These coatings are applied to
preheated pipe surfaces 400°F to  500°F (204°C to 260°C) with and without
primers.  On some  resins, post curing is required for complete cure.  This
coating is applied in a 12  to 25  mil thickness.  The fusion bonded powder
coatings  exhibit good mechanical  and physical properties and may be used
above  or  below ground.  Experience has indicated that on above ground
installations, to  eliminate chalking and for longer service life, it is
recommended to topcoat with a urethane type paint system.  Of all the pipe
coating systems, the  fusion bonded thermosetting resin systems, when properly
applied are the  most  resistant to hydrocarbons, acids and alkalies.

     Perhaps the main advantage of the fusion bonded powder pipe coatings
is that they cannot cover up apparent steel defects because of their lack of
thickness, so they do permit excellent inspection of the steel surface before
and after coating.  The amount of holidays that may occur is a function of
the surface condition and the thickness of the coating specified.  A recent
steel  surface profile study by Dr. Bruno and Ray Weaver of the Steel Structures
Painting  Council (SSPC) found the following effect of blast cleaning on
steel:  "Dr. Bruno and Ray  Weaver of the SSPC explained that viewing shot
or grit blasted  surfaces  in three dimensions reveals surface characteristics
not visible in two dimensions.  SSPC research has uncovered the existence
of abrasive-formed spikes of steel that protrude from one to ten mils from
the surface.

     SSPC researchers have  dubbed these phenomenons "hackles" and believe
that they are formed  by the cutting  action of the abrasive.  Weaver said that
a hackle  may be  created when a piece of abrasive strikes a work stress area.
In three  dimensions,  the  hackle stands out in stark relief against its
surroundings, but  is  barely visible  in two dimensions.

     Dr.  Bruno said that  hackles  are difficult to locate and unpredictable.
One never knows  how many  one will find in any given area of surface studied,
he said,  and their effect on coatings is not known."15
                                     92

-------
     Increasing the thickness of the applied  coating minimizes  this  problem
and with minimum cathodic disbondment characteristics,  it has proven to be
a most serviceable pipe coating.   These  coatings  are available  on  3/4"  - 48"
(1.9 cm - 122 cm) O.D.  pipe.

     The application procedures for thermal bonded  powder resins are less
tolerable of variables  and more care is  required  to properly apply them.
Prior to cleaning, pipe is heated to remove moisture and loosen mill scale.
It is necessary to clean the surface to  a near-white metal  finish  as defined
in SSPC-SP10 (NACE No.  2).

     Pipe is then heated uniformly to the recommended application  tempera-
ture (400°F - 500°F/204°C - 260°C).  Each material  has  its  own  requirements
and tolerance level which must be strictly adhered  to.  If  a primer  is
required there are minimum maximum overcoat times which are necessary to
follow.  The powdered resin is applied by electrostatic deposition to the
12-25 mil thickness specified.  Certain  resins  require  post heat treatment
for proper cure.  Inspection by a minimum of  100  volts  per  mil  of  thickness
is recommended.  Pipe requiring limited  repair  (to  be agreed to between
customer and applicator, perhaps one holiday  per  ten square feet)  due to
hackles, coating imperfections and other minor  defects  shall be repaired by
use of a heat bondable polymeric hot metal patch  stick. A  100  percent  solids
liquid epoxy repair material is recommended within  12"  of each  end of pipe.
Manufacturers recommendations for field  application of  patching materials
should be followed.

     For a more detailed treatment on Fusion  Bonded Thermosetting  Powder
Resins, the reader is referred to the ANSI/AWWA C215-78 standard.

5.   Liquid Epoxy and Phenolics

     There are many different liquid systems  available  today that  cure  by heat
and/or chemical reactions; some are solvent  types and  others 100  percent solids.
Their use is mostly on larger diameter pipes  where conventional systems may
not be available or where they may offer better resistance  to operating
temperatures in the 200°F (90°C) range.

     Generally epoxies have an amine or a polyamide curing agent and require
a near-white blast cleaned surface SSPC-SP10, (NACE No. 2).  Coal tar epoxies
have coal tar pitch added to the epoxy resin.  A coal tar epoxy cured with  a
low molecular weight amine is especially resistant to an alkaline environment
such as occurs on a cathodically protected structure.   Some coal tar epoxies
become brittle when exposed to sunlight.16

     The application for a mill-applied system is as follows:  The  pipe is
placed on rotating rollers mounted on a tracked dolly which automatically
feeds the pipe into a grit blasting machine.   It is cleaned inside  and  out.
Then it is transferred into a spray booth where the interior and  exterior
may be simultaneously coated with  two separate spray coats  to  provide  a dry
film thickness of 12 mils.  After which the coated pipe is  then subjected to
hot air blowers for proper curing prior to inspection  at 100 volts  per mil.17


                                     93

-------
 6.    Tapes

      Polyvinyl,  polyethylene and coal tar  tapes  are widely used In the field
 for joint coating protection or for odd  shapes or bends on mill applied
 applications.  The trend has been to heavier butyl-mastic type adhesives to
 provide better adhesion and  eliminate water migration at the overlap.  When
 tapes are applied at  a coating plant, padding or rockshield must be provided
 to  minimize shipping  damage.  Over the trench, field applied tapes may be
 applied with tape wrapping machines.   Coatings applied over the ditch are
 less susceptible to physical damage because of reduced handling, but they can
 be  more affected by variations in ambient  temperatures and humidity.  These
 along with  inadequate surface preparation  are the main disadvantages of a
 field applied coating system.   The important developments in plastic tapes
 have been an increase in their thickness,  use of stronger resins and improved
 adhesion by the  use of new types of adhesives and primers.  Mill applied
 tapes capable of service temperatures to 210°F  (99°C) are presently available
 and have had limited  use.

 7.    Wax Coatings

      Presently not too much  is heard regarding the use of wax coatings.
 However,  they have been in use over 48 years and are still utilized on a
 limited basis.   Microcrystalline wax coatings are usually used with a plastic
 overwrap.   The wax waterproofs the pipe  and the  wrapper protects the wax
 coating from contact  with the soil and affords some mechanical protection.
 The most popular use  of a wax coating is the over-the-ditch application with
 a combination machine which  cleans,  coats, wraps and lowers into the ditch
 in  one operation.   The fact  that there are no objectionable or toxic fumes
 or  smoke present should make this system more acceptable.

 8.    Polyurethane Foam Insulation

      Efficient pipeline insulation has grown increasingly important as a
 means of  operating hot and cold service  pipelines.  This is a system
 controlling heat transfer in above or below ground and marine pipelines.
 While generally  used  in conjunction with a corrosion coating, if the proper
 moisture vapor barrier is used over  the  urethane foam, effective corrosion
 protection  is obtained.   This  is a plant applied process, where the carrier
 pipe  is centered within the  outer jacket which contains and molds the foam
 as well as  providing  an effective moisture vapor barrier.  Metered quantities
 of foam components  are rapidly introduced  between the carrier pipe and the
 outer jacket.  The  foam is restrained by end caps and rises on a first-in
 basis  forming a  uniform composite unit.  When properly jacketed, usually with
 polyethylene or  coated steel,  the system is moisture and corrosion resistant
 and sufficiently strong  to resist crushing and flexible enough to permit
 allowable field  bending.18

 9.     Concrete

     Mortar lined and  coated pipe have the longest history of use to protect
 steel or wrought iron  from corrosion.19  When steel is encased in concrete,
a protective iron oxide  film forms.   As  long as  the alkalinity is maintained

                                     94

-------
and the concrete is Impermeable to chlorides and oxygen,  corrosion protection
is obtained.  See AWWA C-205 for a detailed reference on  concrete coatings.

     Today concrete as a corrosion coating is mainly limited to internal
lining.  The external application is applied over a corrosion coating for
armor protection and negative bouyancy in marine environments.   A continuous
reinforced concrete coating has proved to be the most effective controlled
method of obtaining desired results.

     Materials including water, sand and/or heavy aggregate, and cement are
mixed in the application plant.  The materials are conveyed by belt to the
throwing heads where controlled-speed belt/brushes throw  the mixture onto
the coated pipe surface.  The rotating pipe is moved past the throwing heads
to receive the specified thickness of concrete.  Simultaneously the galvanized
wire reinforcement is applied with an overlap.  To further increase tensile
strength and to improve impact resistance additional layers of wire or steel
fibers may be specified.20

     We have now covered the most popular protective coatings and described
their properties and how they are applied, but I would be remiss if I stopped
here.  In the foreword to the N.A.C.E. recommended practice "Application
of Organic Coatings to the External Surface of Steel Pipe for Underground
Service,"  I quote, "Experience Shows that a Major Cause  of Pipeline Coating
Failure is due to Improper Application."21  Therefore the selection of an
applicator might prove to be the most important consideration.  A quality
material poorly applied is of little value and the quality of your pipe
coating is only as good as the quality of application.  To assist you in your
evaluation of an applicator, the following points should be considered:*2

     1.   Experience
     2.   Reputation
     3.   Reliability
     4.   Conformance to coating manufacturers specification

     5.   Modern automated equipment
     6.   Quality control

1.   Experience

     A lot of research and also trial and error has gone into  the  develop-
ment of every coating that is now on the market.  This has  required  close
cooperation between applicator, coating manufacturer, equipment manufacturer
and customer.  The transition from laboratory  to production line is  usually
a costly experience but the value of having accomplished this  cannot be
underestimated.

2.   Reputation

     This is an asset that has to be earned through performance as promised.
                                      95

-------
3.   Reliability

     Consistent quality performance that can be depended upon.

4.   Conformance to Coating Manufacturers Specifications

     Manufacturers have established minimum specifications for application of
their materials which should be met, if not exceeded.

5.   Modern Automated Equipment

     Capital expenditure on automated application equipment has been an
important part of the overall success of plastic coatings.  The elimination
of human errors through automation and controls will continue to be an
important factor in obtaining improved pipe coatings.

6.   Quality Control

     Conformance to specifications has to be checked regularly.  Knowledge of
applicators quality control procedures on materials, application and finished
product are essential in the selection of an applicator.

     To summarize, it is not an easy task to select the "best" coating system
for your needs.  This selection requires knowledge of your operating and
installation conditions to be able to evaluate the properties of the pipe
coatings as to filling these needs.  1 reemphasize that selection of a quality
applicator is the most important consideration and frequently is the most
neglected.  After the coating and applicator have been selected, inspection
at the coating mill and especially during construction phases will go far in
assuring that you are obtaining maximum benefits from your pipe coating
system.

REFERENCES

1.   A.W. Peabody, Control of Pipeline Corrosion, Chapter 3 "Coatings",
     p. 9-18.

2.   NACE Standard RP-01-69 Recommended Practice "Control of External
     Corrosion on Underground or Submerged Metallic Piping Systems".
     Section 5.1.2.1, p. 5.

3.   S. Boysen, Jr., "Coating Fundamentals", Appalachian Underground
     Corrosion Short Course, May 1974.

4.   This ASTM method is under the jurisdiction of ASTM Committee G-3
     on deterioration of non-metallic materials.  American Society for
     Testing and Materials, 1916 Race St., Phila., Pa. 19103.

5.   NACE Standard RP-01-69 Recommended Practice "Control of External
     Corrosion on Underground or Submerged Metallic Piping Systems".
     Section 5.1.2.2, p. 5.


                                     96

-------
6.   Jack T. Kluchi, "Plastics for the Protection of Underground Pipe",
     March 1, 1967, Purdue University, 6th Annual Underground Corrosion
     Course.

7.   O.W. Wade and J.F. Gosse, "A Study of Test Methods for External
     Coatings for Underground Pipelines,"  1966 American Gas Association
     Distribution Conference.

8.   Dean M. Berger, "Selecting Coatings for Underground Steel Pipe",
     Plant Engineering. September 30,  1976, p.  105.

9.   R.W. Horner, "Extruded Plastics", May 1973, 18th Annual Appalachian
     Underground Corrosion Short Course.

10.  K. Channing Verbech, "Protective  Coatings," New England Gas
     Association, June 19, 1969.

11.  R.N. Sloan, "Present Trends in Coatings to Protect Pipe Type Cable in
     the Utilities Industry" Materials Performance,  July, 1979, p. 27-30.

12.  R.N. Sloan, "Asphalt Mastic Coatings," Fifteenth Annual Appalachian
     Underground Corrosion Short Course 1970.

13.  N. Schmitz-Pranghe, "Mannesmann's Approach to Extruded PE Mill Coating"
     Pipeline Industry, March 1976, p. 40.

14.  R.N. Sloan, "Extruded Plastic Pipeline Coatings" NACE Southeast
     Regional Conference, Oct. 21-24,  1979.

15.  Dr. Bruno, Ray Weaver, SSPC Research Program American Painting Contract-
     or, Dec. 1976, p. 14.

16.  Dr. Richard W. Drisko, "Introduction to Protective Coatings," p.  7/3.
     Materials Science Div., Naval Construction Battalion, Port Hueneme,
     Calif. 93043.

17.  Linden Stuart, Jr., "Modern Pipe  Coating Techniques and Equipment in
     the Mill and Field".  Corrosion 78, NACE Paper No. 65.

18.  Price, Prilo-K Polyurethane Foam Insulation Bulletin 1977.

19.  John G. Hendrickson, "Internal and External Concrete Coatings for
     Corrosion Control", 15th Appalachian Underground Corrosion Short
     Course, 1970, p. 358.

20.  Pipeline & Gas Journal Staff Report "Steel Fibers Toughen Coating  for
     Offshore Pipelines", May 1975.

21.  NACE T-10D-8 Proposed NACE Standard Recommended Practice  for "Appli-
     cation of Organic Coatings to the External Surface  of  Steel  Pipe  for
     Underground Service".
                                     97

-------
22.  R.N. Sloan, "Protective Coatings", New England Gas Association
     Corrosion Course, Worcester Polytechnic Institute, Worcester, Mass.,
     June 21-23, 1967.
                                     98

-------
                          DISCUSSION ON PIPELINE WRAP

QUESTION  (Mr. Ward):  You talked a lot about oil pipelines and heat waste
          pipeline applications underground.   Would you address the above-
          ground or in-plant steam pipes?

ANSWER    (Mr. Wink):  I did overlook that big market.   Cross-country pipe-
          line is basically what I talked about because that is what I am
          most familiar with.  When you get to your petrochemical plants,
          utility plants, or another type of  industry,  you have overhead
          pipelines.  There is a different corrosion problem as opposed to
          being in the soil.  Different types of coatings must be looked at.
          Most predominant Is the phenolic epoxy, a liquid type coating that
          is sprayed on.

          One important thing to consider is  the temperature of the line.
          You mentioned steam, which can be 800 or 900  degrees; a very special
          painting is needed for this in order to withstand the heat and pre-
          vent the pipe from disbonding.  Napguard could possibly handle
          temperatures of that nature.

          Coatings undergo worse corrosion aboveground  than with a buried
          pipeline and maintenance is probably a year-around aspect of this
          type of situation.

QUESTION  (Mr. Ward):  I am also thinking of thermal insulation.

ANSWER    (Mr. Wink):  For thermal insulation, polyurethane foam is good up to
          about 300 degrees Fahrenheit.  With steam lines, which have high
          temperatures, you probably want to look at calcium silcate.

QUESTION  (Mr. Castleman):  I would like to know how long polyurethane foam
          has be*»n around, and was asbestos insulation used before the poly-
          urethane foam?

ANSWER    (Mr. Wink):  I am really not familiar with asbestos being used as
          an insulation.

QUESTION  (Mr. Castleman):  I mean underground.

ANSWER    (Mr. Wink):  Polyurethane foam, to the best of my knowledge, has been
          used since the early 1950s.  I know a couple of jobs  overseas where
          urethane foam was used, but it primarily replaced calcium  silcate,
          which is a very brittle pipe insulating material.

QUESTION  (Ms. Levy):  I am from the Health Standards Bureau  of OSHA.   This  is
          a general question to all the members of the panel.   I have heard  a
          lot now, and I am encouraged by hearing that you have new substitutes
          for asbestos.  I would like to know to what extent  you are thinking
          about new processes, that is, rather than  just  plugging in a substi-
          tute for asbestos, are you  looking at materials that would change
          exposure levels.  Is any research being done  in that area?

                                       99

-------
ANSWER     (Mr. Wink):   I will  try  to attack the question from my standpoint and
           then I will pass  it  on.   Primarily, whereas applicators are con-
           cerned,  the affect of  asbestos  in our industry is small — it is more
           in  the manufacturing aspect.  In  one material we replaced asbestos
           with fiber glass, and  primarily,  that is what the pipeline industry
           will do—just replace  asbestos  with other  material.

QUESTION   (Mr. Bailie):  Is your question to change  the process of production
           to  handle asbestos or  is it  to  change the  process completely to
           eliminate asbestos?

QUESTION   (Ms. Levy):   Well, I am  unclear as to how  much asbestos you are
           going to eliminate,  but  from what I have gathered, some of the sub-
           stitutes will still  involve  exposures.  There is still going to be
           some exposure unless you change the workers' direct contact to
           some extent,  and  I am  curious about how that is going to come about,
           if  at all, and is there  any  ongoing research?

ANSWER     (Mr. Bailie):  Relative  to the  roofing industry, the exposure to
           asbestos is rather minimal.  It is more prevalent at the production
           point.   To that end, I cannot speak with any authority.  I am sure
           that your department has leaned heavily on the producers of asbestos
           felt to  the point that they  are taking every precaution in changing
           their process.

REMARK     (Chairman Gulmond):  If  I interpret you correctly, you are saying
           that where you may have  a process now that is using asbestos or
           some other kind of fiber, such  as fiber glass or mica, either as a
           filler or as  a binder, are companies changing the processes of
           making those  pipes or  insulations so that  the whole system might be
           enclosed, so  as to eliminate exposure.

REMARK     (Ms. Levy):   Right.

ANSWER     (Mr. Bailie):  I  can only say this, in the area in which our corpora-
           tion uses asbestos,  we have  spent a lot of money to, first of all,
           comply with your  requirements,  and second, to provide as much pro-
           tection  as is possible for the  workers involved.  I think that can
           also hold true for the producer of roofing felt.

QUESTION   (Chairman Guimond):  You have indicated that there seems to be a
           transition occurring from asbestos to alternative materials.  Do you
           know approximately what  fraction  of the market these alternatives
           have at  the present  time?

ANSWER     (Mr. Wink):   I would guess,  offhand, the coal tar industry, which
           is  the biggest user  of asbestos,  is now using fiber glass.  This
           is  about  50 to 55 percent of the  pipeline  industry.  The other
           coatings  comprise the  remaining 45 to 50 percent.
                                      100

-------
                                    TEXTILES

                                       by

                              Mr. Samuel 6. Manfer
                             The Carborundum  Company
                             Niagara Falls, New York
                                     ABSTRACT

    Many U.S. companies,  some of them former asbestos weavers, have expended
    effort into the development of products to replace asbestos textiles.
    Aramids, ceramic fiber, fiberglass and silica have all been processed  into
    textiles which have gained acceptance as substitutes in many applications.

    Major uses for asbestos textiles have been as gaskets, packings, heat  shields
    and personal protection.  Current replacement products have certain, but not
    all, performance characteristics necessary to be suitable substitutes  in all
    applications.  Silica and ceramic fiber products, for example, resist
    extremely high temperature and most chemicals but will not withstand abrasive
    conditions.  Inversely, aramids, while possessing good strength and
    mechanical resistance, can only be used in temperatures under 650°F.

    In most cases, non-asbestos substitutes are more expensive than the asbestos
    products they replace. For certain uses, the additional cost is economically
    justified by a longer service life.  In applications where performance is
    relatively equal, health and environmental considerations are usually the
    justification.

    While many substitutes are available, no one particular product can be
    used to replace asbestos in every application.  Careful consideration of the
    application is necessary to determine the appropriate substitute.
     My  product today is TEXTILES —  Asbestos Replacement Textiles in
particular.   I guess  it may be somewhat bold, but  it is safe  to say that
there  is now a replacement for every  asbestos textile product.   When I  first
became associated with asbestos replacement, price and performance seemed to
be the problem areas.   These are no longer problem areas.  There are products
that are very price-competitive and there are products that perform better
than asbestos.  My  discussions today  will not cover friction-oriented  textile
                                        101

-------
 products such as clutch facings and brake  lining materials.  Additionally, I
 will not talk about dynamic packings.   These topics have been covered earlier.
 The areas I am going to cover are the  woven cloth  and  tapes, ropes and braids,
 tapes and sleevings.

      The market is big — very big —  much bigger  than most people would think
 for this particular product line.   We  conservatively estimate yearly purchases
 of $50 to $70 million dollars or 5 to  6 million  pounds a year for just textiles.
 The business is big with innumerable applications.  The applications are
 welding cloth, maintenance cloth,  furnace  curtains, expansion joints, static
 packings and general packings, furnace door seals, flange  gaskets, burner
 gaskets, boiler door seals, pipe wrapping  and cable protection,  safety garments,
 gloves and insulation sales.  So far,  replacement  textile  products have pene-
 trated only 10 percent.  The big problems  are marketing and user expectations.
 It starts with the user who purchases  from a fabricator or distributor who is
 supplied by the manufacturer.   The user is the key person.  He's really
 unsure of his service conditions.   Asbestos always worked  and was specified.
 Asbestos textiles have been maintained items.  It was  always on  hand and used
 universally.   It always worked and it  was  always specified for key engineered
 applications.

      Direct substitution is difficult.  You just cannot throw in a replacement
 product where an asbestos product  used to  be and expect the exact same
 performance.   Application-by-applicatiori replacement is necessary.  Usually
 traditional mill supply houses, or asbestos specialty  distributors stocked
 and delivered.   The user must now deal with other people.  The forms may be
 different.   Instead of a 40 inch cloth, he may now have to use a 36 inch
 cloth.   Or he may want to use a paper  or a felt  to do  a job.

      There is really little incentive.  What sort of pressure are we putting
 on people?  The dangers aren't really  apparent.  You see asbestos and do not
 take it seriously.   "I'm not going to  get  that fiber into  my lungs.  What
 are the chances of that one fiber  getting  in there?"   A lot of people think
 that way.   However,  there is a lot of  pressure from the foremen  and the super-
 intendents to keep the production  up.   Trying new products causes problems
 that affect production.   This is a big hurdle to overcome.  They want some-
 thing that is  better and cheaper,  rather than safer and acceptable.

      In regard to the fabricator,  they are not too anxious to change either.
 They have  to come up with new methods.  Asbestos used  to crease  when they
were making their blankets.   Substitutes do not  crease too well.  New methods
have to be  used — new molds,  dies,  new forms.   Wetting agents are required
for  coating whereas  plain water or mortar  was  used before.  Problems exist
with irritability, abrasion and dust.

      From  the distributor standpoint,  these are  the people who have to sell
the  product to  the end user.   They need to stock more  products now.  Before
they used  to stock one or two  different types  of asbestos  cloth  and that took
care of all the  needs.   Now they have  to stock maybe 4 or  5 different products
and  that is not  too  attractive.  That  is more inventory, more dollars.  They are
                                      102

-------
unsure how willing the customers are going to accept  and how willing they are
to convert or what they are going to convert to.   They need more initial
service and selling effort to convert the customer.   That means  more salesmen
and more field service.  This means more people or more overhead.   Profitability
requirement for price, discount, and service are  different.   They're different
for the different types of distributors.

     The manufacturers, the people who make these textile products, they
really do not know the end uses.  For so long asbestos manufacturers have been
a material supplier.  The fabricators and distributors really know the nitty
gritty application details.  Manufacturers supplied asbestos and asbestos
worked.  What are the real needs of the end user? What are his  service
requirements?  Does the end user really know whether  his pipeline is 500
degrees or 300 degrees?  Is the door seal going to see 1000 degrees or
really only 600 degrees, or maybe 1500 degrees?  They do not have the knowledge
of the real user problems.  The manufacturers have to develop replacements but
do not know the key applications and the key service  requirements.   They are
held to a specification written around asbestos.   When you  try to make a
product that is around an asbestos specification  and  the product is not
asbestos, it is very difficult to duplicate.  But it  is possible to meet the
service requirements with different materials and forms.

     The manufacturers are not familiar with the  fabricators, or the distri-
butors of the end users' needs.  Some need price, discount, service and some
need different types of performance requirements. Application selling is
required by the manufacturers.  They have to invest in people to get to the
individual accounts, and the individual end users to  find all those applica-
tions one by one and determine what product can replace the asbestos.  These
are what I consider the major problems in replacing asbestos textiles.

     Let me talk a little bit about the products  available  and some of the
requirements necessary for them.  Replacement products have three common
requirements.  They must be temperature resistant, inflammable and flexible.
Cloth products need molten metal resistance, wear and abrasion resistance,
the ability to be fabricated and mechanical strength.  Some examples are
welding curtains, maintenance blankets, slow cool blankets, expansion joints
and furnace curtains.  Packings need resiliency,  chemical stability, durability,
abrasion resistance and the ability to be coated.  Some static packings
used to prevent leaking of gasses, must have good scalability, compressi-
bility and recovery characteristics.  Burner gaskets  and pipe wrappings need
good mechanical strength, vibration strength and  molten splash resistance.
Clothing must be non-irritating, coatable and easy to fabricate.

     There are several types of fibers that are being used for asbestos
substitution.

     Fiberglass is currently very popular with a wide range  of  acceptance.
It can be used very successfully in certain applications.  Advantages are:
it has moderate thermal resistance, 1000 degrees, it can be  blended with
other fibers, it is relatively low cost and it has good mechanical strength.
The disadvantages are;  it has poor abrasion resistance at higher tempera-
tures, it has limited molten metal resistance, it is  irritating to workers'

                                     103

-------
 skin,  and  it  has  poor scalability.   These are  not  concrete advantages and dis-
 advantages.   In each application the advantages  and  disadvantages may be dif-
 ferent.  Some of  the leading contenders—for example PPG  and Owens Corning—
 seem to  be the strong supporters of asbestos replacement  textile fiberglass.
 PPG has  introduced Text'o and Owens  Corning also  has  texturized  fiberglass pro-
 ducts.   The texturized product is a product that was developed, in my
 estimation, to look similar to asbestos  and to provide  thermal  insulation
 characteristics.   Many users are finding that  non-texturized fiberglass or
 continuous yarn fiberglass products are  well accepted in  the marketplace.  It
 is  a trend toward people being open minded. A product  does not necessarily
 have to  look  like asbestos in order to substitute  for asbestos.  Some of the
 products made from this are Zetex fiberglass cloth and  Uentley Harris rope
 products.

      The advantages of ceramic fiber are good  heat resistance  (it withstands
 2300 degress  without any degradation and can withstand  temperatures up to
 3000 degrees),  it is inflammable, it has good  thermal shock resistance, it has
 molten metal  resistance, it can be  blended with  other material.  It has
 good mechanical strength, good chemical  resistance,  and can be  coated and
 fabricated.   Major disadvantages are its abrasion  resistance, it needs organic
 carriers to be formed and it is abrasive.   There is  one form that 3M produces
 that does  not have an organic carrier.   It is  a  continuous form as opposed to
 a staple.  Another form of this is  leached silica  fiber.  The advantages here
 are good heat resistance, heat resistance to 1800  degrees, inflammability
 and good molten metal resistance.  Disadvantages are that they  are brittle at
 the higher temperature, have poor abrasion resistance and are moderately high
 cost.  New aramids have heat resistance  to 600 degrees, have high strenth
 in  the Kevlar form, are non-abrasive,  can be blended with other fibers and
 have good  scalability.   Aramids are good in the  packing areas.  Disadvantages
 are low  strength  (Nomex), they are  difficult to  weave and cut  (Kevlar) and
 they are moderately high cost.   Some of  the leached  silicas are Refrasil and
 Siltemp.   The aramids are Nomex and Kevlar, both made by  Dupont.  Amatex
 also fabricates aramids into a line of textile products.  Other new fibers
 are carbon fibers which have good thermal properties, scalability and lubricity.
 Disadvantages are lack of flexibility, poor abrasion resistance, limited
 vibration  resistance, and very high cost.   Another fiber  is stabilized
 PAN or better known are the Preox materials.   Advantages  are flexibility,
 vibration  resistance, good tear strength and good  fabrication characteristics.
 Disadvantages are heat resistance,  molten metal  resistance, cyanide for-
 mation upon heating,  and high cost.

     Carborundum  feels very strongly and is committed very seriously to ending
 the no asbestos blues.   We feel strongly that  asbestos  can be substituted
 for.  We are  heavily committed to this right now and have a line of textile,
 paper, board  and  cement products.   Our feeling is  that  if people are open
 minded about  changing the form it does not necessarily  have to  be a textile
 to  serve the  need.

     For example,  we have successfully wrapped pipes with paper as opposed to
wrapping it with  a textile tape.  It is  a low  cost way  to insulate a pipe.
The  disadvantages  are that it does  not have a  good durability or abrasion
resistance.   However,  if it is  covered,  it is  a  low  cost  way to go about


                                      104

-------
replacing asbestos textiles.  Another example is a CalRod heater used by the
Navy.  Where they formerly used textiles, they now use ceramic paper.  Gas-
kets have been cut out of textile products.  They are now being replaced by
board and lightweight papers that serve the same need.  Board products are
replacing textile cloths in the steel industry as splash protection.

     Asbestos is a widely used fiber.  It has been around a long time and
has had over a century for development of uses and applications.  The replace-
ments may work but they are not identical to asbestos.  People must have the
desire to convert.
                                      105

-------
                             DISCUSSION ON TEXTILES

 QUESTION  (Mr.  Cronin):   I am with the Safety and Health Department of the
           Steel Workers  Union.

           My first question is about fiber diameters.   I have  seen products
           like  your own, for example, manufactured  in many  different  fiber
           diameters, ranging all the way from 10 to 15  microns on the upper
           end,  down to,  for some products, the submicron size.   I am
           wondering first, why would one use a larger diameter in some
           applications and a smaller diameter fiber in  others?

           Second,  what is the cost differential for those two  different
           kinds of fibers?

 ANSWER    (Mr.  Manfer):   The way Carborundum makes  fibers and  the way most
           ceramic  and fiber glass manufacturers make their  product is the
           longer the fiber, the greater the diameter in a staple form.
           Usually, the longer the fiber, the more mechanical strength in a
           product.  That is the reason for the long fiber.  The short fiber
           is used  for more volume orientation, so you can use  it in rein-
           forcing  applications, which do not need mechanical strength, but
           need  a heat dissipater.

           Cost-wise, I would probably say the short staple, from our  vantage
           point and that of most ceramic manufacturers, is  cheaper because
           it can be produced much faster and in large quantities.  A  slower
           process  is required to make the longer fiber  and  it  is therefore
           more  expensive.

           Are you  looking for relative cost differential?

 QUESTION  (Mr.  Cronin):   Why would one use very thin fibers at all?   What
           is the reason  or advantage for using the  fibers about which there
           have  been, at  least, some preliminary health  questions?

 ANSWER    (Mr.  Manfer):   Usually a fine fiber is necessary  for insulation.
           The finer the  fiber, the more air void you can create;  the  more
           air void,  the  better the insulator.

 QUESTION  (Mr.  Cronin):   Let me ask you one final question.  In the very
           beginning of your talk you said you know  of a nonasbestos textile
           replacement for every asbestos use.   Is there a nonrespirable
           or  a  thick fiber replacement,  and let us  define that as being
           more  than 5 micrometers,  for every current asbestos  textile
           use.
ANSWER
(Mr.  Manfer):   I am not sure.
                                    106

-------
QUESTION  (Mr. Cronin):  Can you, for example, make the Insulation layer
          thicker?  For example, can y6u achieve the same effect as high
          temperature Insulation with thicker fibers and a greater massive
          Insulation as in a thicker insulation layer around a furnace?

ANSWER    (Mr. Manfer):   Yes, you can.   The problem is the thicker the fiber,
          the less air space you have,  and the thicker the material.   I know
          of many fiber glass uses above the 5 micron level.   I think they
          are running about 10 microns.   Fiber glass can not replace every-
          thing.  Ceramic fibers can range from 3 to 10 microns, and they
          replace a lot of asbestos.  I am not exactly sure what the other
          fibers diameters or lengths are.

QUESTION  (Mr. Weiner):   I am from the Navy Department.

          Did I hear you correctly to say that cyanides come off of carbon
          fibers, or was that another fiber you talked about?

ANSWER    (Mr. Manfer):   No, it was stabilized PAN, which is polyacrylic
          nitrate, also called Preox.  It is not off the carbon fibers.

QUESTION  (Mr. Castleman):  I divide my time between working as a consultant
          for the Office of Toxic Substances of the Environmental Protection
          Agency, working for the Environmental Defense Fund, and working
          for attorneys representing plantiffs in damage suits against the
          asbestos industry.

          I would like to know if Carborundum is feeling pressure from the
          Importers of Amatex, who, as you must know, plays on both sides
          of the fence and has two asbestos textile plants in Mexican border
          towns; is this hurting your ability to market your product?

ANSWER    (Mr. Manfer):   I would say asbestos Imports do not help our
          situation.  I cannot specifically say that it has hurt us, I
          cannot claim any damage, but it does not help.

QUESTION  (Mr. Wyblan):   I am from the University of Minnesota.

          Going back to fiber diameters, do you have a general idea of  the
          range of diameter, say, for something that you are calling  10
          microns?  What is the range of the size distribution  for fibers
          like that?

ANSWER    (Mr. Manfer):  I really have to defer that to my technical  people.

QUESTION  (Mr. Ross):  I am from the U.S. Geological Survey.

          Let us pursue diameters a little more since  you want to replace
          all asbestos with a product, I assume, that  will not cause
          disease.  Yet you do not know much about  the fiber diameters.  You
                                     107

-------
           see, if we start replacing asbestos with substitutes with fiber
           diameters in the respirable range,  then a health problem might
           arise 20 years from now.   I think we should be a little  harder
           nosed about what we are going to replace with what.  We  could
           bring a substitute on the market that can be worse than  what we
           replaced.

 ANSWER    (Mr. Manfer):   That is a very good  point.  Let me put  it this way.
           I do not want to steal anybody's thunder tomorrow who  is going to
           be talking about this product, in particular.   We belong to an
           organization called TIMA, the Thermal Insulation Manufacturers
           Association.  For the last 20 years, they have been doing studies
           on fiber glass and ceramic products.  Ceramic fiber is not new;
           it has been around since the early  1950's.   So far,  TIMA has not
           shown any negative results from ceramic fiber.  It is  a  smooth
           fiber, it is not like asbestos, and it does not get caught in your
           lungs; it can be expectorated.  The fiber diameter is  large enough,
           usually, so that it gets stuck in your throat before it  goes
           down to the lungs.

           Let me assure  you that for the last 20 years TIMA has  been working
           with ceramic fiber and fiber glass  materials and nothing has been
           proven.   It is difficult  to prove a negative—we do  not  know what
           will happen in the next 30 years—but for the last 20  years the
           testing has shown no carcinogenic or ill  effects.

 QUESTION   (Mr.  Guy) :   I  am from the Weyhaeuser Company.   We have a severe
           problem with the door gasketing or  door seals,  under what I would
           call high temperature applications  for 500  to  600°F.   Do you still
           feel that there is an appropriate substitute material?  We have
           trouble with resiliency and,  secondarily, with abrasion  resistance.
           The resiliency problem has not been satisfactorily solved with
           either asbestos material  or gasketing door  seals,  or with the re-
           placement materials.

ANSWER     (Mr.  Manfer):   I definitely think there is  a replacement product,
           and that is one of our best sellers.   It  is a  ceramic  rope that is
           very resilient,  in high temperature applications.   I am  not going
           to  say that I  can come in and replace your  rope tomorrow,  nor will
           the fiberglass,  Siltemp,  or aramid  people,  but  we can  work with you,
           anybody  can work with you,  and over time, you will get a suitable
           replacement.

QUESTION   (Mr.  Guy):  Do  you know if any of these substitutes  are  silicon-
           based or have  other kinds of  internal structures  to  support them?
           Or  are they straight  replacement material?

ANSWER     (Mr. Manfer):   It is  hard to  say they are straight replacements
          because  substitution  occurs on a application-by-application
          basis,   I am not  sure what you mean by silica  support.
                                    108

-------
                     ASBESTOS  SUBSTITUTES IN ROOF COATINGS

                                      by

                            Dr. Kenneth Brzozowski
                                 Tremco, Inc.
                                Cleveland, Ohio




                                    ABSTRACT

    Asbestos is used in roofing products, and,  to a lesser degree, in sealants
    and caulks for the variety of properties it imparts to these products.
    Specifically, asbestos is used for sag or flow control, reinforcement,  coating
    hold out, etc.  A large number of substitutes have been proposed and offered.
    None, however, have been found that duplicate the performance of asbestos.
    The substitutes found most suitable are very costly.  In some cases, they
    are as much as twenty times more expensive.
     As with other  industries, the building waterproofing industry has been
concerned about a possible ban on the use of asbestos  in its products.
Tremco, as I am sure  many other companies marketing waterproofing materials,
has been very active  in searching for and evaluating the dozens of asbestos
substitutes that are  presently on the market.  Very briefly, let me mention
some of the substitutes that have been offered to our  industry:

     Precipitated Calcium Carbonate
     Ground Rice Hulls

     Shredded Newspaper/Clay
     Shredded Newspaper
     Ground Fly Ash
     Fumed Silica

     Citrus Flour

     Polyethylene Fibers
     Fiberglass

Let me say at the outset that our search, though long  and extensive,  has not
been completely successful.  We have not been  able  to  uncover  a material that
performs in a manner  similar to asbestos.  The primary problems that  we have
encountered with substitutes are:

                                      109

-------
      1.    Cost

      2.    Oil Absorption

      3.    Sag Resistance
      4.    Settling

      5.    Appearance  of Product

 COST

      I will now give  a few details  on each  of  these problems.  Our experience
 is  that  asbestos replacements  are priced  anywhere from two to twenty times
 higher than asbestos.  Depending on the product the replacement is going into,
 this  translates into  a finished  cost of between 10 percent and 150 percent
 higher.   These  higher costs would obviously have to affect the selling price
 to  the user or  consumer.

 OIL ABSORPTION

      Oil absorption is the amount of oil  required to wet or be absorbed by a
 specific amount of pigment or  filler - in this case asbestos or asbestos re-
 placement.   The higher the oil absorption of a filler used in a formulation,
 the greater the viscosity of that coating or sealant or caulking material or
 whatever.   Our  experience indicates that  most  of the substitutes now on the
 market have lower oil absorption characteristics than asbestos.  This means
 more  substitute must  be used to  achieve the same viscosity in a product.  This
 of  course,  relates to the cost considerations  which I have already mentioned.

 SAG RESISTANCE

      Sag resistance is the tendency of an applied wet film of material to
 remain stationary or  resist excessive flow.  For example, when you apply a
 paint  or caulking to  a vertical  surface,  you want it to remain in place and
 uniform  on  the  wall or in the  vertical joint.  Again, we have found many of
 the substitutes deficient in this property.  Even, with very high loading,
 i.e.  large  amounts of  filler added  to the formulation, we have been unable to
 obtain acceptable sag  resistance properties with these substitutes.

 SETTLING

      Settling is  a term used to  describe  the process in which there is
 separation  of solid material from the vehicle  to the bottom of the container.
 Obviously,  excessive settling, especially settling in a short period of time,
would make  the  product unusable.  Most asbestos substitutes have not per-
 formed well with  regard to  sag resistance.
                                     110

-------
APPEARANCE OF PRODUCT

     Our experience indicates that products "look" different when asbestos is
replaced.  We do not view this to be a serious problem,  but are cognizant of
the fact that our customers would have to be alerted of  any change and re-
educated in the use of our products should asbestos be removed.

     Turning from coating properties to safety considerations,  we feel
comfortable with using asbestos in our products.   Some time ago,  we converted
to the use of compacted asbestos in our products  to reduce the  concentrations
of asbestos in the air when handling it in our plants.  This required some
alterations in manufacturing procedures, but was  a relatively straightforward
change.  Further, we require that only whole bags of asbestos be  used when a
batch of product is manufactured.  This causes us to adjust batch sizes
to accommodate whole bags, but eliminates the hazard of  having  opened partially
filled bags laying around a plant.  We also have  installed highly efficient,
closed-system exhaust units in all our plants. Asbestos levels in our plants
are monitored by Tremco personnel and, in addition, we have outside testing
services check our results on a regular basis. Our air  samples always indicate
that we are orders of magnitude below the maximum safe limits.

     While our coating and caulking materials are being  applied and when they
are in service, the asbestos is locked into the vehicle  and presents no hazard.

     Thus, from a safety point of view, we see no reason to place a ban on
asbestos in the type of products we manufacture.

     Despite the technical problems I have mentioned and the lack of hazard we
perceive, we are very actively pursuing substitutes for  asbestos  or ways to
eliminate fillers altogether.  This year, for example, Tremco introduced what
we believe is the first solvent-free asbestos-free roof  rejuvenating coating.
We were able to accomplish this without a large increase in selling price and
without sacrificing performance.  It is our intention to continue on this
path; namely introducing asbestos free products that perform as well or better
than present products with little or no increase  ip cost.  This will be
accomplished as our technology allows us and/or new raw materials become
available.

     However, should a ban be placed on asbestos  tomorrow, Tremco would not be
out of business.  We have asbestos free formulations for all our present
products.  These products would not perform as well as existing products and
would be more costly.  Our chief concern is whether the suppliers of the
substitutes could produce the enormous amounts of material that would be
required if asbestos is banned.

     To summarize:

     1.   We have been unable to discover a single fiber that can be used
          across our product line as a substitute for asbestos.
                                      Ill

-------
2.   Formulating techniques and the use of several asbestos substitutes
     have allowed us to develop product formulas which are asbestos free.
     These products are inferior in performance and higher in cost when
     compared to asbestos containing formulations.

3.   We feel that asbestos, as presently used in our products, is safe.

4.   Tremco is concerned that enough asbestos substitute materials would
     be available if asbestos is totally banned.  Especially since all
     users would be competing for the best substitute materials.

5.   Over a period of time, Tremco expects to phase asbestos out of its
     products, but only as technology and raw materials become available.
                                 112

-------
                             OVERVIEW OF ASBESTOS
                           SUBSTITUTES IN SEALANTS,
                           ROOF COATINGS AND CEMENTS

                                      by

                               Mr.  Eric Wormser
                           The Gibson-Romans Company
                                Twinsburg, Ohio
                                    ABSTRACT

     In spite of extensive research, the industry has not found a raw material that
     is a  satisfactory  substitute for asbestos fibre in roof coatings and roof
     cements.  Complicated formulating techniques have been developed by isolated
     manufacturers of roof coatings and cements that enables them to produce  satis-
     factory products without asbestos.  These products are more expensive than
     those containing asbestos and are of lesser quality.  A ban in the near  future
     on asbestos fibre  in roof coatings and cements would result in large volumes
     of vastly inferior products being sold to the public, in the speaker's opinion.

     The majority of caulks and sealants currently on the market do not contain
     asbestos fibre. Reformulation of those caulks and sealants which do contain
     asbestos fibre should not present a serious problem.


     Dr.  Brzozowski has  given you a technical exposition into the current
state of  asbestos  fibre  substitutes in roof coatings,  roof  cements and seal-
ants.  I  will give a  non-technical overview in.to the situation.  It will take
only one  minute  to discuss the problems of substituting for asbestos in seal-
ants.  That is simple.   I  plan to use the remainder  of my time to discuss with
you the far more serious and complicated problems of trying to eliminate
asbestos  fibre in  roof coating products.

     We are not  aware of any significant amounts of  asbestos fibre being used
in calks  and sealants.   Mr. Gurtowski did mention some aircraft sealants where
asbestos  so far  has defied substitution.  Caulks and sealants are liquid or
semi-liquid gap  fillers  used in building and equipment construction.  They  are
made from elastomers, synthetic or natural oils, bodied into suitable consis-
tency, which may be pourable but more often is much  thicker.  In our  own com-
pany we still have a  few specialized formulas containing asbestos fibre.  In
the absence of regulations banning the use of asbestos in caulks and  sealants,
we have customer resistance in a few cases  to making the necessary  changes  in
properties and purchasing  specifications,  in order  to use substitute materials,
However,  should  the use  of asbestos fiber no longer be permitted  in these
products, I do not foresee a serious problem in coming up with acceptable
formulas  that do not  utilize asbestos.

                                    113

-------
      Now let us  turn our  attention  to  roof  coatings  and cements.  First I want
 to  explain the difference between these products.  Roof coatings are cold
 applied  liquids  that are  used  to  rejuvenate and  protect almost any type of
 roof, except usually not  the typical home shingle  roof.  Typical types of
 buildings utilizing roof  coatings are  home  garages,  porch decks, apartment
 houses,  sheds, farm buildings,  industrial buildings  and commercial buildings
 of  all sorts, including stores, shopping centers and office buildings.  These
 coatings are applied by brush  or  spray.

      Roof cements  are trowel applied compounds.  Their consistency is similar
 to  soft  margarine.   They  are used to seal openings large enough so that liquid
 coatings would run through them.  Roof cements are used on almost every type
 of  building regardless of the  roofing  system  employed, including the typical
 shingle  roofed home.   They are used to seal between  vertical and horizontal
 surfaces and around projections such as vent  pipes,  chimneys, roof heating
 and air  conditioning units, gutters, and gravel  stops, the list is almost
 endless.

      Approximately 65 percent  of  our company's sales of roof coatings and roof
 cements  go  through retail stores  to the homeowner  and handyman type applicator.

      The sheet roofing systems  described by speakers are almost universally
 applied  by  the professional roofer.  Roof coatings and roof cements are used
 to  protect  most  of these  systems  also.  I do  not believe that anyone is
 suggesting  that  sheet systems  that  do  not contain  asbestos can replace roof
 coatings  and roof  cements.  Should  anyone entertain  such an idea, a study of
 the needs of the building owners  will  clearly show that roof coatings and
 cements  are necessary supplements to the roofing sheet systems.

      Roof coatings  are also used  as waterproofing  mastics on porous walls of
buildings,  above and  below ground - on surfaces  such as concrete block, poured
 concrete  and brick.   There are a  number of  types of  roof coatings.  By far
 the largest segment of this business is in  coatings  consisting of asphalt
 liquified with solvents and bodied  with asbestos fibre.  Once the asphalt is
 liquified with solvents sufficiently so that  it  can  be readily applied to the
 surface without  heating,  the asbestos  fibre is the vital ingredient for several
reasons.   Without  the asbestos, the liquified asphalt will penetrate entirely
into  the  surface it  is supposed to  rejuvenate, leaving little or no protec-
tive  layer  on top  of  the  surface.   On  the type of  surfaces where there is no
penetration,  such  as  on metal, if there is  a  slope to the roof, the liquified
asphalt will sag or run in the absence of asbestos fibre.  In addition, the
asbestos  serves  to  reinforce the  asphalt.   After the solvents have evaporated,
the asbestos  fibre  prevents the asphalt from  cracking as the surface moves
with  expansion and  contraction from temperature  changes.  A roof goes through
large temperature cycles  in every 24 hour period.  The asbestos fibre also
retards the  oxidation and deterioration of  the asphalt.  This deterioration
results from severe exposure to the actinic rays of  the sun that is typical
for roofs.  Last but  not  least, in  the event  of  fire, the asbestos fibre will
retard melting and running of the roof coating.
                                     114

-------
     So far no single raw material has been found that will replace the func-
tions performed by asbestos fibre in solvent thinned asphalt roof coatings.
There is a variety of other types of roof coatings sold.   Their total volume
is far less than the asphalt solvent coatings,  so far as  asbestos is used,
are at least to a degree similar to those described for the asphalt solvent
coatings.

     As mentioned earlier, large quantities of  roof cements are used in addi-
tion to the coatings.  As already mentioned,  almost without exception, no
matter how a roof is originally constructed or  later repaired,  these trowel
consistency cements are utilized in that construction and repair.  These
cements commonly are solvent thinned asphalt or coal tar  bodied into a heavy
consistency with asbestos and other mineral fillers.

     To date no raw material has been found to  equal the  properties of asbes-
tos fibre in achieving the needed body.  To perform their function these
cements must be suitable for troweling and at the same time must contain
enough bitumen after evaporation of the solvents to deposit a thick film on
the roof surface that has good weathering integrity.

     The industry has had a strong incentive to find a way to manufacture roof
coatings and roof cements without asbestos fibre.  Consequently a tremendous
amount of work has been done.  One aspect of this incentive has been the
tightening regulations by EPA and OSHA and the  threat of  regulations that
would make it impractical to continue to use asbestos. Another incentive has
been pressure from customers who prefer not to  sell or use products that con-
tain asbestos because of the large volume of bad publicity surrounding it..
The greatest incentive, however, that the industry has had to formulate around
asbestos is the recurring disruptions in asbestos supply  that we have exper-
ienced in recent years.  Over the last 5 years  our purchasing staff has spent
more time fighting to get enough asbestos to keep our plants running than any
other single raw material.  We have vowed to get away from the use of asbestos
because we cannot afford to be as dependent upon a raw material as we are on
asbestos, when it seems every other year or so  there is a critical shortage.

     In spite of the tremendous amount of work  that has been done to try to
find a substitute raw material that will produce satisfactory roof coatings
and roof cements, to the best of our knowledge  no one has found such a material.
As the result of our company's vast research, by complicated formulating tech-
niques, utilizing a variety of ingredients and  techniques, we are now able to
produce solvent base asphalt roof coatings and  roof cements that do an adequate
job without asbestos fibre.  We assume that there are some other manufacturers
in a similar position.  We do not yet offer these asbestos free roof coatings
and cements for sale in the United States because they are about 15 percent
more expensive to produce and we believe they are not as good as comparable
products made with asbestos.  It is difficult to justify selling an inferior
product for more money.  We are shipping considerable quantities of asbestos
free coatings and cements to Sweden, where the  use of asbestos fibre  in  such
products has been banned.  Therefore, we are gaining experience  in  the volume
manufacture of such products and have the opportunity to observe their per-
formance in large scale use.
                                    115

-------
     We  feel strongly  that  a ban in our  country on  the use of asbestos fibre
 in  roof  coatings  and cements would be  profitable  to our company because we
 could  furnish our customers workable products whereas most of our competitors
 could  not.   At the same time, we feel  that  such a ban would be a great dis-
 service  to  the American public.   In view of the stringent OSHA requirements
 for handling of asbestos fibre in the  manufacture,  and EPA requirements for
 disposing of wastes, no one is being injured by the use of asbestos in our
 plants.  Once the asbestos  is bound in the  roof coating and cement vehicles,
 it  can do no harm to anyone.  Therefore,  a  ban would not benefit anyone.  On
 the other hand, it would force on the  American public a flood of very poor
 products at high  prices.

     Let me explain why it  has not been  possible  to make roof coatings and
 cements  of  equal  quality with substitute raw materials.  Asbestos fibre is
 unique among known raw materials in that it is a  completely inert, indestruc-
 tible  mineral that can be processed into a  fibre.   This fibre partially
 absorbs  the vehicle into which it is placed and becomes an integral part of
 that vehicle, without  settling or floating.  Small  amounts of asbestos fibre
 add a  large degree of  body  to the vehicle,  so that  relatively small amounts
 of  asbestos turn  a thin liquid into a  consistency akin to apple-butter.  What
 other  inert inorganic  fibres are there?   Very few.  Glass is completely un-
 absorptive.   Therefore it is not possible to make a homogeneous coating out
 of  a vehicle with glass fibre.   Glass  fibre floats  in roof coating vehicles,
 unless it is held down with something  else.  As a matter of fact, we make
 some glass  fibre  roof  coatings and cements  and we hold down the glass with
 asbestos fibre.   There is a rock wool.   In  our experience it does not have
 the absorption properties that will permit  a homogenous mixture.  Fibrous
 talcs, wollastonites,  ceramics and clays  are not  fibrous enough to duplicate
 the performance of asbestos.  Most other  fibres that are available are organic
 in  nature.   They  melt,  they deteriorate  on  ageing and most have poor chemical
 resistance.

     Although we  do not know of a fibre  that can  be satisfactorily substituted
 for asbestos in the manufacture of roof  coatings  and roof cements, nothing is
 impossible.   We consider it unlikely however that such a fibre will be found
 in  the foreseeable future.   The only method we know for manufacturing reasonably
 satisfactory asbestos  free  roof  coatings  and roof cements is to combine some
 less than satisfactory substitute fibres  with a variety of mineral fillers,
wetting  agents, plasticizers and synthetic  thixotropes.  We manufacture about
 250  different roof coatings,  cements and  mastics.   A variety of techniques
must be  used to achieve acceptable results  in each  of these products.  The
 end  result in every case is  a product  that  contains considerably less asphalt,
 tar  or other water proofing  oil  and much  more filler material than when asbes-
 tos  is used.   These fillers  contribute nothing to the waterproofing properties
or weathering  of  the products.   To the contrary,  these filler materials often
detract  from the  desirable properties.  These formulas require from 30 to 70
percent more  energy in  our plants  to manufacture.

     There are Federal  Specifications covering asphalt roof coatings and roof
cements.   Although we have developed asbestos free  formulas which we feel are
of acceptable quality,   they  do not meet the  standards in the Federal Specifi-
cations.   In  every  case  the  asbestos free formulas  exceed the maximum filler

                                     116

-------
content permitted by these specifications.  The writers of these specifications
rightfully specify a minimum ash content for the fillers that are used.  These
we are also unable to meet with our asbestos free formulas.   At the present
state of the art, the General Services Administration would  have to lower its
purchasing standards for asphalt roof coatings and cements,  as would the
non-government buyer, in order to utilize asbestos free products.

     I need to explain to you my statement that if the use of asbestos fibre
in roof coatings and cements was banned, the market would be flooded with
very poor products, so poor as a matter of fact that they would be virtually
useless.  Our company currently ships over twenty million gallons of roof
coatings per year.  We believe we are the largest manufacturer of roof coatings
in the world.  Most of our "competitors ship two to five million gallons.  These
competitors cannot afford the research we have spent on developing asbestos
free formulas or the dollars that we will continue to commit to this project.
Relatively few of our competitors in the roof coating business even have
laboratories.  In any typical asbestos free formula, there is no one raw
material that represents sufficient volume so that it is really worthwhile
for raw material suppliers to do adequate research.  Raw material suppliers
have touted numerous suggested asbestos free formulas, none  of which will
make a satisfactory product.  During recurring periods of asbestos fibre
shortages we have seen examples of the type of products that some of our com-
petitors have shipped in desperation.  Their only choice was to close their
doors because they could not get asbestos or ship the best they could make
without.  What they shipped was a disaster.  These events bring us to the
strong belief that should there be an asbestos ban, in order to stay in business,
the numerous small competitors will be forced to ship products that are a dis-
service to the industry and the user.

     Another aspect needs to be considered.  The hazards of  asbestos fibre
have been thoroughly researched and documented.  They are real but readily
controllable and limited.  We know little or nothing about the hazards of the
variety of raw materials we use in order to manufacture asbestos free roof
coatings and cements.  We get material safety data sheets from our suppliers.
None of the new raw materials are known carcinogens.. It is  unlikely, how-
ever, that anywhere near the amount of research into the health hazards of
these materials has been devoted as has been to asbestos. You will, during
this workshop, get a health report on only some of the alternate materials
that may be used in asbestos free coatings.

     The supply picture of the combination of materials needed to make asbestos
free coatings must also be taken into account.  Several of the raw materials
are highly specialized and produced in small volumes.  We have determined on
some of the materials that the supply is far short of what we would need if
our company converted its entire production to asbestos free coatings and
cements.  We have not investigated whether it is possible to expand the supply
in every case to that which would be needed to cover the entire industry.  I
would assume that given time and sufficient demand a way can be found to supply
the needs of the industry with these materials.  However, if there should be
a sudden ban on the use of asbestos fibre in roof coatings and cements, the
available raw material supply would not meet the demand from our company, to
say nothing of meeting the industry's demand should other manufacturers want
to use the same methods.

                                     117

-------
TO SUMMARIZE

     1.   There are a number of types of roof coatings and roof cements.

     2.   The predominant type that is sold is solvent base asphalt roof
          coating and roof cement.

     3.   We do not know of a substitute for asbestos fibre in these products
          nor in any other type of roof coating.

     4.   We can make asbestos free solvent base roof coatings and cements
          by complicated formulating techniques.

     5.   We believe our company would benefit from a ban on asbestos in
          roof coatings and cements.

     6.   Such asbestos free products are more expensive than those containing
          asbestos fibre and we believe inferior in quality.  They do not
          meet existing Federal Specifications.

     7.   I do not foresee a change in this picture in the foreseeable
          future.

     8.   Little is known about the health hazards of some of the raw materials
          we would use in order to produce asbestos free coatings and cements.

     9.   The supply of some of the raw materials we would use is inadequate
          to meet our company's requirements to say nothing of industry
          needs.

    10.   If asbestos were banned in roof coatings and roof cements, in my
          opinion, the market would be flooded with products so inferior in
          quality that they cannot perform the purpose for which they are
          intended.
                                     118

-------
QUESTION
                DISCUSSION ON SEALANTS

(Chairman Guimond):  I have a question for Mr.  Wormser.   You men-
tioned the Federal specifications that require, I think you have
indicated it was ash content.  Someone yesterday mentioned to me
that a certain Federal specification, SSC-153-C, actually speci-
fies required amounts of asbestos.
ANSWER
QUESTION
(Mr. Wormser):   That is correct.
specifies asbestos.
That specification actually
ANSWER
ANSWER
(Chairman Guimond):   Is that  frequent  in  specifications  to actually
specify that you must have X percent of asbestos or it must con-
tain asbestos or contain certain other materials as opposed to a
specific performance?

(Mr. Wormser):  I think there are other specifications that do specify
asbestos.  Possibly Dr. Brzozowski is more familiar with the details
of the specifications.

(Dr. Brzozowski):   I could not give you the exact  number,  but many
of the Federal specifications for roof coatings require asbestos
in the material.
QUESTION  (Chairman Guimond):  As a consequence, I would gather that to be a
          very strong hindrance at the present time for you to be able to sell
          roof coatings not containing asbestos to the Federal government?

ANSWER    (Mr. Wormser):   I would say until the Federal government changes their
          specifications we would not be able to provide them with roof
          coatings and roof cements.

REMARK    (Mr. Hughes):  I have a comment that is prompted by Mr. Wormser's
          observation about the effects of recurring shortages of fiber.
          I think this is one of the often unrecognized forces that asbestos
          regulation is imposing on the industry.  The fact is that there
          has been no investment in new asbestos fiber production capacities
          except in the Soviet Union.  The reason is simply because of the
          very hostile regulatory attitude that prevails in the United States
          and in some other countries.  It is very difficult to justify in-
          vestment and yet we see these recurring shortages.  It imposes
          substantial costs on the consuming industry and it is a direct re-
          sult of regulatory actions.
                                    119

-------
                         GLASS FIBER REINFORCED CEMENT

                                      by

                                Mr.  John Jones*
                              Cem-FIL Corporation
                             Nashville, Tennessee

                                      and

                             Mr. Frank W. Fekete
                          GRC Products, Incorporated
                                Schertz, Texas
                                   ABSTRACT

   The paper will present physical properties and characteristics of glass fiber
   reinforced cement (GRC) and how these are affected by different composite formu-
   lations.  In addition, it will discuss the various processes for manufacturing
   GRC and how these affect the characteristics of GRC.  A comparison with asbes-
   tos-cement and other possible substitutes will be made throughout the paper.
   Both the' economics of•GRC versus asbestos-cement and several applications where
   GRC has been adopted as a substitute will be discussed.
INTRODUCTION

     Glassfiber  reinforced cement (GRC) is basically a composite of a hydraulic
binder, such as  portland cement, reinforced with glass fibers, with or without
fillers or additives.   In this respect it is similar to asbestos-cement with
glassfibers as the reinforcing agent instead of asbestos fibers.  Like asbestos-
cement, GRC is not just one material but is a whole spectrum of composites  each
with different performance characteristics depending on factors such as the type
of cement used,  glassfiber content, type and quantity of filler and/or additive,
and the density  of the composite.

     Although GRC has  many possible formulations,  the predominant basic compo-
site is based on portland cement with an inert filler such as sand or limestone
fines and reinforced with a special alkali resistant glassfiber.  Much of this
paper discusses  this particular type of GRC and it will be referred to as high
density GRC.
*Presented by Mr.  John Jones.

                                        121

-------
PROPERTIES

     Figure 1 gives  the basic physical properties of GRC containing 5 percent
by weight alkali resistant glassfiber.  These are compared with manufacturers'
data for asbestos-cement.

     GRC has properties similar  to  those of asbestos-cement with one notable
exception: impact strength,  in which GRC is approximately ten times stronger
than asbestos-cement.

     Although original formulations of GRC lost a significant amount of this
high impact strength over a  period  of a few years under natural weathering con-
ditions, the long term impact strength was still higher than that of asbestos-	
cement.  However, recent improvements in alkali resistant glassfiber have sig-
nificantly improved  long term durability.  Figure 2 illustrates the magnitude
of this improvement  in the retention of the area under the stress-strain curve,
a measure of the impact and  abuse-resistance of the material.

     All GRC formulations will satisfy ASTM 136 as regards non-combustibility
and will be rated 0  on all characteristics measured by ASTM E84.  However, high
density GRC (like asbestos-cement)  can explosively spall when subjected to very
rapid temperature rise as experienced under fire conditions.

     Some characteristics of GRC can be changed by changing its formulation.
Thejmal insulation,  fire performance, and high temperature performances are
three such properties.

     The use of perlite (or  a similar lightweight filler) can reduce the density
by up to 50 per cent.  The effect of reducing density on properties such as
thermal insulation can be seen in Figure 3.  Also, these formulations provide
GRC products with excellent  fire resistance properties.  Figure 4 shows the
fire ratings achieved for different thicknesses of sheet with a density of
approximately 62 Ibs. per cu. ft.   During the tests the sheets showed not only
excellent fire resistance, but showed no tendency to spall or crack even after
the fire test was stopped and the sheet cooled down.

     GRC based on portland cement can be formulated to have good fire resistance
properties and satisfactory  performance at high temperatures for a short period
of time.  However, these composites do not usually perform well under prolonged
exposure at elevated temperatures,  unlike asbestos-cement which performs well
up to 600°F and in some cases higher.  However, recent lab tests and product
field trials have shown that GRC based on high alumina cements and reinforced
with alkali resistant glassfiber will perform well certainly up to 600°F, and
some recent results  suggest  possibly up to 1000°F.

     Although these GRC composites  under prolonged exposure at elevated tempera-
ture lose some strength and  embrittlement is evident, comparative tests against
asbestos-cement have showed  that high alumina GRC performs in actual service at
least as well as asbestos-cement.

     Some areas where high alumina  GRC has been compared favorably with asbestos-
cement are in furnaces and ovens, and in high temperature electrical equipment.

                                      122

-------
                                  FIGURE 1

                       Physical and Thermal Properties
                                     of
                            Asbestos-Cement Board
                                     and
               High Density Glassfiber Reinforced Cement Board


                                           *ACB                GRC

Dry Density, Ibs. per cu. ft.               100             123 to 128
Moisture Content
     (% of Dry Weight)                    5 to 13             2 to 8
Water Absorption
     (% of Dry Weight)                 22 (48 hrs.)       5-10 (24 hrs.)
                              6
Modulus of Elasticity psi x 10             1.5                 2.4
Compressive Strength, psi                 12,000         10,000 - 16,000
Tensile Strength, psi                      1,400          1,600 - 2,200
Transverse Strength, psi                   4,000          3,300 - 4,000
Shear Strength, psi                        3,500          5,300 - 7,200

Brinnell Hardness                           25                 29
Thermal Expansion, In/In/°F x 10"6          5.0              1.3 to 7
Dimensional Change Due to
     Moisture, In/In
     Shrinkage (Normal to Dry)            0.0020             0.0014
     Expansion (Normal to 90% RLF)        0.0006             0.0004
     Expansion (Normal to Saturated)      0.0028             0.0015
Maximum Service Temperature, OF             600                600
Surface Burning, ASTM E-84                 0-0-0              0-0-0
Permeance, Perms                            12             Less than 2
Freeze-Thaw Resistance                  Satisfactory      Satisfactory
Thermal Conductivity,
     BTU/In/Sq.Ft./Hr/°F                    4                   5

Impact (Falling Ball),
     Energy Absorption, ft. Ibs.            18                 229
*The data for ACS are taken from the literature of ACS suppliers.
                                      123

-------
            FIGURE  2
Flexural Stress-Strain After the
Equivalent of  30 Years Weathering
                                IMPROVED GLASSFIBER


                                  ORIGINAL GLASSFIBER
                  0.5
PERCENT  STRAIN
               124

-------
                    FIGURE 3
             Comparative Properties
                       of
         Low and High Density GRC Sheet

     Density, Ibs.  per cu.  ft.             125    62
     Modulus of Rupture, psi             4000  2000
     Water Absorption                      16    22
          (Max. % of Dry Wt.)
     Thermal Conductivity                 5.0   2.0
          (BTU/In./Ft.2/Hr./°F
     Maximum Service Temperature, °F      600   600
                    FIGURE 4
              Results of Fire Tests
          Conducted on Low Density GRC

Thickness ,
In.
0.688
1.181
3.076
Unit
Weight ,
pcf
**
78.4
73.6
Relative
Humidity
Per Cent
38
72
73
Fire
Endurance*,
hr:min
0:18
0.58
5.35
 *Determined by the ASTM El19-79 criteria for temperature rise
  of the unexposed surface.

**Not weighed.
                        125

-------
     Although 6RC can often offer comparable performance to asbestos-cement,
it is not an exact replacement.  For  instance, the physical appearance of GRC
sheet is not yet as good as asbestos-cement in either surface smoothness or
thickness uniformity  (process developments in progress are expected to correct
this).  GRC sheet, although it cuts as easily as asbestos-cement, does not fabri-
cate as neatly  in that  there is more  chipping and break-out around the cut edge.

MANUFACTURE OF  GRC

     The primary process that has been developed for GRC manufacture is based
upon a spray concept  in which the cement  slurry is pumped to a nozzle through
which it is atomized  into  a spray cone.   Simultaneously glassfiber roving is
chopped, usually to a length from 1 to 2  inches, and the chopped strands are
blown into the  cement slurry spray.

     In small to medium scale production  the spray-gun can be held by an opera-
tor, but more commonly  it  is mounted  on a simple traverse mechanism which re-
ciprocates back and forth.  The spray is  deposited either into a mold or onto
a dewatering table  (the purpose of dewatering is to extract the excess water
and compact the sheet).

     Such a spray dewatering machine  is used by Cem-FIL Corporation (Nashville,
Tennessee) for  flat and corrugated sheet  manufacture.  Where much higher volumes
are required, equipment has been developed that can produce several million
square feet per year.   GRC Products,  Inc. (Schertz, Texas) is commercially op-
erating such a  facility.

     Progress has been  made in developing techniques to manufacture GRC sheet
on the Hatschek process that is used  for  asbestos-cement production.  GRC sheet
made by this method has a  modulus of  rupture of about half that of asbestos-
cement sheet, but has been used successfully as a substitute in several
applications.

ECONOMICS

     The manufacturing  cost of GRC is quite dependent on the scale of manufac-
ture.  GRC sheets made  on  the medium  volume process described above are about
two to two and  a half times the price of  asbestos-cement sheet.  Where the
high volume process or  the Hatschek process is operated, GRC costs are around
50 percent higher than  asbestos-cement.   When GRC manufacture becomes more com-
parable with the scale  of  asbestos-cement manufacture, the price differential
could well be reduced to 20 percent or less.

     At the moment, 1/4 inch thick GRC sheet is available at about 80
-------
     A full range of flat sheets from 1/8 inch through to 4 inch thick is
available from inventory in 4 ft. by 8 ft. sheets.   Standard 4 ft. by 10 ft.
sheets are available in thinner sheets between 1/8  inch and 3/8 inch.   Corru-
gated sheets in the standard 4.2 inch pitch are also available.

     Where high temperature performance or fire protection is required, two
grades of flat sheet are in the advanced stage of field trials and are avail-
able for product performance trials.

APPLICATIONS

     Pullman Standard Company has used 1/4 inch thick GRC sheet as the replace-
ment for asbestos-cement sheet in the lining of electrical closets in Amtrak
passenger cars.  Amtrak also uses GRC sheet for the same purpose.  In this use
the asbestos-cement provided both fire resistant lining and some thermal insula-
tion so that if a fire were to occur in the closet, the lining would protect the
steel stairway from the upper deck for a sufficient time to allow passengers to
escape.  GRC sheet was the only substitute that offered the same fire resistance
performance as asbestos-cement.  Although the thermal conductivity of high den-
sity GRC is slightly higher than asbestos-cement, it was satisfactory for the
purpose.

     E. I. Dupont uses both flat GRC sheet and corrugated sheet as replacements
for asbestos-cement.  The corrugated sheet is used for repair and maintenance
of existing asbestos-cement clad buildings, and for new construction.   Flat
sheet is used for a variety of uses within the plants, particularly fire resis-
tant linings and partitions.

     Several manufacturers are testing GRC sheet as fume hood linings and one
company has already started to utilize it in their range of hoods.  GRC offers
the same chemical resistance as asbestos-cement, being resistant to most chemi-
cals except strong inorganic acids.

     The heat resistant grade of GRC has been extensively tested by a variety
of oven and furnace manufacturers.  In particular,  several manufacturers of
pizza ovens have approved its use as a substitute for shelves and linings.

     GRC sheet, both flat and corrugated, has been used on a limited scale in
cooling towers.  Flat sheet has been substituted for asbestos-cement in cell
partitions and fan decking and corrugated sheet has been used for louvers and
end-wall and stairwell casings.  GRC has demonstrated the same excellent dura-
bility and rot resistance as asbestos-cement under the extreme conditions that
exist in cooling towers.

     GRC has been used in a wide range of building uses, particularly architec-
tural panels.  Wide use is now made of GRC in custom-molded claddings and in-
creasing use is being made of flat GRC sheet in spandrel, soffit, and fascia
panels.

     GRC is being evaluated as a substitute for asbestos-cement  in  light  duty
waterfront bulkheading on canals, inlets and estuaries.  GRC corrugated sheet-
ing will probably be approved for this use, since load tests and field trails
have demonstrated its structural suitability.
                                      127

-------
CONCLUSIONS

     GRC is not a development material, but in fact, has been in use for over
18 years.  Although some of the products are going through evaluation trials,
the basic material is backed by years of service use as well as by extensive
laboratory testing.

     Some of the technology for high volume sheet manufacture is new, but pro-
ducts made on such processes are readily available and are being sold and used
commercially.

     The principal reason that GRC is proving to be the most widely used mater-
ial as a general substitute for asbestos-cement sheet is that it has the same
excellent general properties, such as good mechanical strength, good chemical
resistance, rot proofness, fire resistance, heat resistance, and the ability
to be simply machined and fabricated.

     Although many materials may be superior in any one of these characterise
tics, only GRC is like asbestos-cement in that it offers an excellent balance
of all these features.

     Although GRC is at the moment more expensive than asbestos-cement, there
is no doubt that with continued and increasing scale of use over the next few
years, the price differential will shrink considerably, and quite possibly could
disappear completely.
                                      128

-------
                 OTHER SUBSTITUTES FOR ASBESTOS-CEMENT  SHEET
                                       by

                               Dr. David Cogley
                                GCA Corporation
                            Bedford, Massachusetts
                                    ABSTRACT

    Asbestos-cement sheet is defined in terms of special qualities  imparted by
    asbestos.  Market share is discussed for the four basic forms of asbestos-
    cement sheet:  flat sheet, corrugated sheet, siding shingles, and roofing
    shingles.  Both product substitutes and fiber-for-fiber replacements are con-
    sidered for low temperature and high temperature applications.  Substitute
    products include cement/wood board, mineral insulating boards,  aluminum sheet,
    wood, and brick.  Each product alternative is discussed in detail including
    product manufacture, composition, durability, life, cost, and market trends.
    A wide variety of substitute products are available for most asbestos-cement
    sheet applications.
     Asbestos-cement (A/C) sheet products have  been used for many years in the
United States.   I will briefly describe the variety of A/C products available,
their uses, and  special properties.  Substitute products suitable for some A/C
product applications will be discussed.  Included  will be comparisons of  com-
position, strength  and durability, cost, life expectancies and market trends.

     Asbestos-cement sheet products represent about 6 percent of the total
amount of asbestos  used in the United States annually.   Although used mainly
in construction  applications such as roofing and siding for both industrial
and residential  buildings, it is also an ingredient in the manufacture of
heaters, boilers, vaults and safes, electrical  equipment mounting panels,
welding shields, and many other products where  a noncombustible or heat-
resistant sheet  is  required.

     Asbestos has become important as a reinforcing agent due to its avail-
ability, price and  unique combination of the following properties:

     •    tensile strength

     •    flexibility
     •    resistance to heat

     •    chemical  inertness and

     •    large  aspect ratio.         129

-------
     Asbestos  fibers  in cement  sheet  add  to  the strength, stiffness and tough-
ness of  the material, resulting in  a  product that is rigid; durable; noncom-
bustible;  resistant to heat, weather, and attack by corrosive chemicals; and,
in addition, stable.   A significant feature  of A/C sheet is that it possesses
sufficient wet strength to  enable it  to be molded into complex shapes at the
end of the production process.2 As a result, A/C sheet can be found in four
basic forms:

     •     flat sheet

     •     corrugated  sheet
     •     siding shingles,  and

     •     roofing shingles.

     Substitutes are  being  sought for a wide variety of A/C sheet products.
For flat sheet, the applications range from  internal and external paneling,
decorative paneling,  cooling tower  fill,  fume hoods, and thermal and fire pro-
tection  walls, to electrical equipment mounting panels.  For each of these
applications,  performance requirements vary  and it is to be expected that
several  different substitute products will be required.  Corrugated sheet is
used primarily as a construction material where the additional strength afforded
by corrugation is of  benefit.   Siding shingles constitute a single product class
with performance requirements expected to vary according to the geographic loca-
tion of  product use.   Similar remarks apply  to roofing shingles.

     Among the properties that  may  be important for any particular application
of A/C sheet,  one may consider  the  following:

     •     physical strength

     •     fracture toughness
     •     high temperature  performance

     •     electrical  conductivity
     •     resistance  to moisture
     •     resistance  to freeze/thaw cycle, and

     •     overall weather resistance.

Of two possible ways  of evaluating  performance, that is performance specifica-
tions or use specifications, we have  chosen  use specifications.  This is con-
sistent  with the experience of  industrial manufacturers as well as standard
setting  organizations  such as ASTM  (The American Society for Testing and
Materials).  Just  as  special formulations are employed to achieve optimal
performance of A/C products, it is  to  be  expected that special formulations
and product development  efforts will be required for substitute products.  For
many if  not most of the  substitute  products  to be discussed today, this fine
tuning stage has yet  to  be reached.  Results to date show promise but as we
heard for friction products, further development effort will be required
before economically viable substitutes for all A/C sheet applications become
a reality.   Substitutes  for A/C sheet  include:

                                      130

-------
     •    housing materials such as wood shingles, stucco,  concrete block,
          brick, unreinforced cement shingles and asphalt shingles;

     •    laminated hardboard (Benelex)

     •    cement/wood board

     •    polypropylene layered cement sheet

     •    insulating boards (such as Monolux)

     •    alumina sheets (Alumina-sheet), and

     •    glass-reinforced cement sheet, which was discussed by John Jones.

Masonry, galvanized steel, reinforced plastics, and wood can also compete in
certain situations.  This paper concerns itself mainly with product replace-
ments not fiber replacements.

     Brief descriptions of composition and manufacturing methods are provided
for seven substitute products.  These descriptions are followed by a discussion
of limitations of substitute product uses.

     Laminated hardboard, such as Benelex, is made from wood.  Wood chips are
first reduced to fibers by a steam explosion process.  The  unwanted elements
in the wood are driven off, leaving cellulose fibers and lignin, a natural
bonding agent.  The fiber is refined and then formed into panels.  It is cur-
rently manufactured by Masonite Corporation of Michigan.3

     Cement/wood board can be used as an alternative to A/C sheet in some flat
sheet applications.  It is composed of specially treated wood fibers bound with
Portland cement.  This board will soon be produced by The International Housing
Corporation of California.  To make cement/wood board, wood fibers are treated
with various chemicals including ammonium chloride, sodium chloride, and sodium
silicate in a process called "mineralization" to remove the resins, acids, and
sugars present in the wood.  These treated fibers are combined with cement to
form cement wood board.

     Polypropylene cement sheet is manufactured by Conwed Corporation of St.
Paul, Minnesota.  Details of its manufacture are not available.

     Insulating board products such as Monolux are made of calcium silicate
cement and selected fillers, reinforced with alkali-resistant glass and wood
fibers.  Monolux is currently made in England by Cape Boards and Panels, Ltd.,
and marketed in the United States by W. B. Arnold & Company.4

     Alumina-Sheet is over 90 percent alumina with about 8 percent silica
fibers.  Zircar Products, Incorporated, of New York now manufactures this
product.  It was developed as an asbestos board replacement  for certain  uses
and is suited for a wide range of high temperature, high thermal shock
applications.5*6
                                      131

-------
8
     Roof  tiles,  such as Monray  by Monier Company of California, consist
mainly  of  Portland  cement,  sand, and water.  The desired color is sprayed on
near the end  of the production process.7

     Roofing  shingles such  as  CeDurShake are made of fiberglass-reinforced
polyester  resin.  They are  currently produced by Trim Products of California.

     The suitability of substitute products for specific uses is described
next.   Some products have a narrow range of applications, whereas others such
as  glass reinforced cement, discussed  previously, are suitable for many prod-
uct applications.

     The laminated  hardboard product Benelex is used for laboratory table tops,
for floors of locomotives and  cabooses, and as a phase barrier in electrical
switchgear and control apparatus.  Laminated hardboards such as this could
replace ebonized  asbestos in many electrical applications.3  Benelex is not
intended for  products requiring  resistance to weather or high temperature.

     An alternative product such as cement/wood board is claimed to combine
the best properties of wood and  cement.  It is rated noncombustible and is said
by  some to be virtually impervious to  weather.  Its modulus of rupture and
resistance to impact are greater than  A/C sheet and, unlike A/C sheet, it can
be  glued and  laminated.  Cement/wood board has good heat and sound insulating
properties, is easily machined,  and has surfaces suitable for multi-purpose
treatment.  It also has good elastic properties under a static load.  Applica-
tions include: external claddings, sound attenuating walls, balcony parapets
and floors, walls separating gardens,  partitions, noncombustible wall and
ceiling linings,  roof soffits, refuse  shafts, ceilings, fascia, and farm stable
linings.   It  has  also been  used  to build prefabricated houses and pavilions.9

     Participants at the A/C sheet round table discussion have indi-
cated that at least the cement/wood board products manufactured in Europe
during  World  War  II showed  poor  resistance to weather.  They indicated further
that cement/wood  board is susceptible  to excessive expansion due to absorption
of water by the wood component during  wet weather.  It is thus thought by some
not to  be  suitable  for exterior  cladding.  Several means of combatting this
tendency to swell cost might thereby be increased.  These potential corrective
measures include:   saturation  of the wood component with resin, painting, use
of  special fasteners to allow  expansion of sheet products without fracture,
or  incorporation  of 3-5% mica  to reduce expansion.

     Polypropylene  cement sheet  is a type of plastic cement board displaying
flexibility and good resistant properties.  This product is comparable to A/C
sheet in its  resistance to  freezing, thawing, combustability, and aging.
Since it is a type  of plastic  cement board it is flexible and will not fracture
as easily as  A/C sheet.  It  is used for construction of cooling tower spray
baffles, buildings,  and other  large structures.10

     Monolux  is a non-conbustible industrial insulating board which is rigid,
non-friable,  durable,  inert, and resistant to attack by insects and vermin.
The board is non-caustic, and  unaffected by dilute acids and alkalis, brine,
chloride,  or volatile solvents.  It will not disintegrate, warp, or swell under

                                     132

-------
prolonged immersion in water and is more resistant to heat than A/C sheet.
It can be used to make small ovens and dryers,  high temperature ducts, oven
shelves and interleaves, and as secondary insulation for furnaces and kilns.1*

     The alumina-silica product called Alumina-Sheet also exceeds A/C sheet's
resistance to heat.  Available in either a moldable or rigid form, it is
being used as an insulator in induction core applications, as a molten metal
transport trough, and as a material for repairing holes in furnaces.   In
addition, the possibility of using Alumina-Sheet for laboratory table tops
exists.  Although not as strong as A/C sheet, its upper temperature limit
is several times greater.  It is very tough and abrasion resistant.5*6

     When comparing cost, the products mentioned vary from being quite a bit
less expensive than A/C sheet to being 10 times as costly1*"6'9'11'12.  Accord-
ing to a product cost comparison between cement/wood board and A/C sheet done
by the cement/wood board manufacturer, the most expensive mill price of cement/
wood board is less than half the cost of Johns-Manville Flexboard A/C sheet
and less than one-fourth the price of J/M transite A/C sheet.  Alumina-Sheet
is more than 10 times as expensive as transite, but the price is expected to
be cut in half as production increases this year.5

     Steel is less expensive than A/C sheet and aluminum is competitive.13
Monier Monray roof tile and CeDurShake roofing shingles cost between $100-$130
for an installed square  (a one hundred square foot roof surface), about the
same as Supradur A/C shingles.8'9

     Availability of the substitutes covered here is also a critical factor in
their use.  Substitute products have already been developed to suit most
applications formerly held by A/C sheet.  A product such as cement/wood board
has been in use in Europe and the Middle East as an all-purpose building board
for a number of years.9  Most others discussed are currently in the market-
place.  Unlike other industries now using asbestos which have embarked on a
series of research and development programs to find alternative nonasbestos
products, the A/C sheet industry has already identified and put into production
substitute products with new, nonasbestos formulations which in some cases
exhibit better performance characteristics.

     In summary, A/C sheet was first used in the early 1900's; substitutes  to
this product have generally only been developed recently, although,  in some
applications, materials such as wood and masonry have always been available;
newer substitute products are available and appear to function well  in place
of A/C sheet, but lack the advantage of being time-proven.   In general, how-
ever, a variety of products incorporating the qualities of A/C sheet at a
competitive price are available as substitutes for A/C sheet in many of  its
present applications.  It is expected that further product development work
will produce viable substitutes for the remaining applications.

REFERENCES

1.  Cogley, D. C., and N. K. Roy, et al.  Asbestos  Substitute  Performance
    Analysis.  Draft Report.  U.S. Environmental Protection  Agency,  Office
    of Pesticides and Toxic Substances, Washington, D.C.   March 1980.

                                     133

-------
 2.   Pye, A. M.  A Review of Asbestos Substitute Materials in Industrial
      Applications.  Journal of Hazardous Materials (Amsterdam).  3:125-147.
      1979.

 3.   International Housing Corporation.  Notebook containing information
      about Cement/Wood Board.  Sacramento, California.  1979.

 4.   Telecon, Swanson, C.  Manager, New Applications Division, Conwed Corpora-
      tion, St. Paul, MN with P. McGlew, GCA Corporation, CCA/Technology
      Division, June 23, 1980.

 5.   Cape Boards and Panels, Ltd.  Monolux Industrial Handbook.  M1077914.
      Uxbridge, England.

 6.   Telecon, Hamling, C., Zircar Products, Inc.  Florida, New York.
         \
 7.   Telecon, Porter, Jr., S.  Marketing Assistant, Monier Company, Orange,
      CA, with S. Duletsky, GCA Corp./Technology Division.  February 15,
      1980.

 8.   Smaus, R.  Roofing Reaches New Heights.   Home, a supplement of the
      Los Angeles Times.  January 27, 1980.  pp. 8-11.

 9.   International Housing Corporation.  Notebook containing information
      about Cement/Wood Board.  Sacramento, California.  1979.

10.   Telecon, Swanson, C., Manager, New Applications Division, Conwed
      Corporation, St. Paul, MN with P. McGlew, GCA Corp./Technology Division,
      June 23, 1980.

11.   Telecon.  Lewis, W.H., GRC Products, Inc., Schertz, TX, with
      S. Duletsky, GCA Corp./Technology Div., February 11, 1980.

12.   Telecon.  Bostian, J., Asbestos Fabrications, Inc., Charlotte, NC
      with S. Duletsky, GCA Corp./Technology Division, March 7. 1980.

13.   Weston, Roy F., Environmental Consultants, Technological Feasibility
      and Economic Impact of OSHA Proposed Revision to the Asbestos Standard
      (Construction Excluded).  Asbestos Information Association/North
      America.  March 26, 1976.
                                        134

-------
             DISCUSSION ON SUBSTITUTES FOR ASBESTOS-CEMENT SHEET

QUESTION (Mr. Singe):  I have a question for Mr.  Jones.   I am an architect with
         the Navy Public Works Center in San Francisco.

         Since Johns-Manville apparently has gone out of the AC sheet produc-
         tion, at least on the West Coast,  we have been  unable to obtain either
         corrugated or flat sheet.   When you say  that your product has a stan-
         dard U.S. corrugation could I conveniently slip it into an existing
         transite corrugated wall?

ANSWER   (Mr. Jones):  When I say the standard U.S.  corrugation,  I mean that the
         corrugated sheet has been  basically produced by the asbestos industry
         has been 4.2 wave length.   In that respect it is the same as the sheet
         you used.  However, before we could decide whether you could just fit
         it in, we would have to check out  the wind loadings to make sure that
         you had adequate support there. As I said, you cannot necessarily
         always substitute thickness for thickness.   But certainly it is a very
         easy thing to do.  It is a I- or 10-minute job  just to check that out.

QUESTION (Mr. Singe):  My second question is, and it is  also meant as food for
         thought for the EPA, in a  lot of products like  pipe installation,
         like your corrugated sheet, we have a product that is very similar
         to the former asbestos-containing  product.   Our construction workers
         often cannot tell the difference between a newer product containing no
         asbestos and the former product containing asbestos, so they treat
         everything as containing asbestos; thereby, costing us a lot of money,
         and costing the taxpayer a lot of  money  because asbestos-containing
         sheet requires special handling.  I would like  to see a product like
         yours, if it is used for replacement of  AC sheet, stamped or labeled
         or somehow coded on the back as containing no asbestos so we know
         what would require special handling and  what does not require special
         handling.

ANSWER   (Mr. Jones):  We do this when we send out a pallet of sheet.  The shroud
         that goes on the pallet does have  a stamp on it that says it is
         asbestos-free or contains  no asbestos, but it is not actually on each
         individual sheet.

REMARK   (Mr. Singe):  Well, this is what we would need.

REMARK   (Mr.  Jones):  It is one we are certainly thinking about.   Just on that
         point, one of the things that we did try in the past was to slightly
         pigment the sheets to differentiate them form asbestos, but unfor-
         tunately we ran into a lot of problems.   Some problems were attributed
         to inconsistency in pigmentation that caused one batch of sheets to
         be quite a bit different from another batch'.  Also people who wanted
         to continue using 6RC wanted the product to have the same appearance,
         so it was somewhat self-defeating and we have since abandoned  the
         approach.  But individual  labeling of the sheets is probably a  good
         thought.

                                      135

-------
REMARK    (Mr. Spell):  I am from Johns-Manville.

         First of all I want to congratulate Cem-FIL on a good job in the
         development of their Cem-FIL glass and the glass fiber reinforced
         cement products and I want to congratulate Mr. Jones on the way he
         discussed the fact that you cannot use the numbers that are printed.
         In other words, modulas of rupture does not mean a thing.  What
         really counts is what strength can you count upon in the material and
         the strength that you can count upon in the glass-reinforced cement
         for the long run, is the strength of the matrix.

         One point that he. did not mention is the fact that alkaline-resistant
         glass is not alkaline-resistant.  It resists alkali better than normal
         glasses.  So you still have a rate of reaction with the cement and
         that rate of reaction is temperature-dependent.  In fact, the rate
         of reaction increases about twice for every 10 degrees change in
         temperature.  The data that were presented are data in weathering in
         England, which is relatively mild.  In Washington in the last few
         days I think the rate of reaction would have been about three to four
         times greater and the life spans that were mentioned would have been
         thus reduced by that same amount.  When you take a look at the 28-day
         strength data you have to view that with a little bit of trepidation
         as compared to asbestos cement, which increases in strength with time.

REMARK   (Mr. Jones):  I would just like to respond to that.  The weathering data
         are not just based on temperate climatic conditions in England.  Ever
         since the start of the project weathering sites have been established
         around the world and the data have always been taken as an amalgam of
         test data from all the various weathering sites.

         These weathering sites are in places like Nigeria, where you have
         tropical conditions, and hot desert conditions such as exist in the
         Middle East.  We have weathering sites throughout the United States.
         We also have various freeze/thaw weathering sites.  So, the data are
         not just based on a temperate climate condition.

         I accept the point that, yes, hot, wet conditions are worse than hot,
         dry conditions, for instance.  In hot, dry conditions you get very
         little change in physical properties; in hot, wet conditions you do.
         But in addition to the live long-term weathering program, there is
         also an extensive amount of work being done on hot-wet conditions.
         By hot* wet I mean hot water over 50°C and we have now an accelerated
         weathering procedure that will stimulate the worst conditions, which
         are tropical conditions, and a lot of the data form an amalgam of all
         these different conditions.  It is not just one particular condition.

QUESTION (Mr. Speil):  I realize that you have weathering stations all around.
         Would you give us the length of time that it takes for the strength
         to decrease in, let us say, Nigeria?
                                      136

-------
ANSWER   (Mr.  Jones):   Now you are getting a little bit out of my realm.   The
         material always reaches a stable level.   It does not continue to fall.
         That is one thing I should point out.   So, we are just  talking about
         the rate at which it reduces to reach the stable condition.   The
         quickest place to reach the stable level has been determined in places
         like Singapore and Nigeria to be about 2 years.  In conditions such as
         those in England, it is about 4 to 5 years to reach the same level and
         in the hot desert conditions it can take 10 to 15 years.  But I should
         stress that the stable level is the important level from the point of
         view of the design considerations and the design velocity we have
         takes into account the stable level that is reached.

         I should also stress that I am talking about the original Cem-FIL
         fiber on which a lot of the long-term test data is based.  For the
         fiber that was introduced earlier this year, much of the data are
         simply based on accelerated weathering programs and, to my knowledge,
         we only have about 2 years of actual data on that fiber.  There you
         are extending the length of time by about a factor of  5 to 10 depending
         on the particular environmental conditions.

QUESTION (Mr.  Speil):  Four to five from your own people.

ANSWER   (Mr.  Jones):  Well, it depends on the particular environmental
         conditions.

QUESTION {Mr.  Speil):  However, the stable level will be the same:  2,000,
         approximately?

ANSWER   (Mr.  Jones):  For the original fiber.

QUESTION (Mr.  Speil):  What is the new fiber?

ANSWER   (Mr.  Jones):  For the new fiber it is about 3,000.

ANSWER   (Mr.  Speil):  It will be 2,000.

REMARK   (Mr.  Hawley):  I am from Marietta Resources.

         Getting back to this question of marking nonasbestos products to show
         that they are asbestos-free* this is in fact being done by two, at
         least, and possibly three manufacturers of calcium silicate pipe insula-
         tion using suzorite mica.  The mica is put in a small percentage.
         It is visible because it is an amber colored flake, a rather  large
         flake, and this is a mark that shows that the product is  asbestos-free.

         To do this on sheet products you would have to do it on the back  layers.
         I do not know if it would be possible for you to do it  with GRC, but
         I think it would be possible.  The advantages of  this type of product
         are that it is inert, it will stand up to any amount of weathering, it
         does not change color, and it is highly visible for the amount of
         dollars involved.
                                      137

-------
REMARK   (Mr. Spell):  I might add that Johns-Manville is using that mica to mark
         their calcium silicate insulation and we think it is a very good way
         of doing it.
                                     138

-------
                   SUBSTITUTES FOR ASBESTOS-CEMENT PIPE

                                      by

              Mr. Richard A. Simonds and Mr. James L. Warden*
                      U.S. Department of the Interior
                      Engineering and Research  Center
                              Denver, Colorado
                                   ABSTRACT

The Water and Power Resources  Service  (formerly called Bureau of Reclamation)
has installed over 9,600 miles of water conveyance pipelines, ranging in
diameter from 4 inches to 21 feet,  that have incorporated many types of pipe.
Since the first asbestos-cement (A/C)  pipe was placed in 1957 on a Service
project, over 1,100 miles of asbestos-cement pipe has been installed by this
agency.

A/C pipe has proved to be quite competitive — approximately 80 percent of all
pipe that is 24 inches in diameter  or  less, regardless of pressure class, in-
stalled on Service's projects  is A/C pipe.

The Service has 13 different types  of  pipe that it considers for use in con-
struction specifications for water  pipelines.  Each of these types of pipe are
manufactured to Service specifications or have been proof tested to meet
Service requirements.  The 13  different types of pipe are divided into 2 groups,
rigid and flexible.  Each group has its own design parameters, pipe trench
requirements, and installation practices.

Usually each type of pipe is a composite of two or more different types of
material, such as cement, rock aggregate, steel, ductile iron, asbestos,
plastics, and fiberglass.

Each type of pipe has its own  particular advantage over the other types of
pipe or it would cease to be manufactured.  These advantages could be:
economics, size, pressure range, resistance to certain internal and external
environments, strength, and acceptability by the purchaser.

Topics to be discussed include:  types of pipe, materials used in manufactur-
ing, design and development of each type of pipe, performance standards,
installation practices, and economic comparison.
*Presented by Mr.  James L.  Warden
                                     139

-------
INTRODUCTION

     The Water and Power Resources Service, formerly the Bureau of Reclamation,
was created in 1902 for the purpose of reclaiming lands and developing water
resources in the arid west.

     In the period between 1902 and 1940 nearly all irrigated lands were
served by open ditches.  Only a few pipelines were constructed and those were
mainly unlined steel pipes, cast-in-place concrete pipe and some wood staved
pipe.
                            i
     In the period between 1940 and 1955 nearly all irrigation water pipe
distribution systems were low head, less than 25 feet of head (11 lb/in.2).
The pipe used was unreinforced concrete pipe with mortared joints.  Most of
these systems have been replaced, but some are giving satisfactory service.

     In the mid-fifties the rubber gasket pipe joint became available to all
pipe manufacturers, and this revolutionized the pipe industry.  Pipe could be
laid much more rapidly and efficiently.  The rubber gasket created a flexible,
watertight joint; hence, there was an increase in confidence in underground
pipe systems.

     New types of pipe were being designed for higher pressures and new mater-
ials were being used to make pipe; therefore, with all the competition between
the pipe manufacturers the costs lowered so that pipe was very, very competi-
tive to the smaller capacity open irrigation canals.  So competitive, in fact,
that the Service designs and builds very few open lateral distribution sys-
tems today.

     The Service has 13 different types of pipe that it considers for use in
construction specifications for water pipelines.  Each of these types of pipe
is manufactured to Service specifications or has been proof tested to meet
Service requirements.  The 13 different types of pipe are divided into two
groups, rigid and flexible.  Each group has its own design parameters, pipe
trench requirements, and installation practices.

     Usually each type of pipe is a composite of two or more different types
of materials, such as cement, rock aggregate, steel, ductile iron, asbestos,
plastics, and fiberglass.

     Each type of pipe has its own particular advantage over the other types
of pipe or it would cease to be manufactured.  These advantages could be:
economics, size, pressure range, resistance to certain internal and external
environments, strength, and acceptability by the purchaser.


THE SERVICE'S EXPERIENCE WITH ASBESTOS-CEMENT PIPE

     Over 9,600 miles of pipelines, ranging in diameter from 4 inches to
21 feet, of various types of pipe have been installed on the Service's projects,
which include some of the largest pipe distribution systems for irrigation
water in the world—Westlands Water District and the Navajo Indian Irrigation

                                      140

-------
Project with 670,000 acres and 110,000 acres,  respectively.   Over  1,100 miles
of asbestos-cement pipe have been installed since  the  first  asbestos-cement  pipe
was installed in 1957.   The Service uses an average  of 50 miles  of asbestos-
cement pipe per year, with a maximum of 130 miles  Installed  in 1973.

     Asbestos-cement pipe has proved to be quite competitive—approximately
80 percent of all the pipe that is 24 inches in diameter or  less,  regardless
of head, that is now installed on Service's projects is asbestos-cement pipe.

     The Service now has had 23 year's of experience with asbestos-cement  pipe
and we use it with confidence.  No asbestos-cement pipeline  has  ever  had  to  be
replaced because of deterioration on a Service project.


DESCRIPTION.OF ASBESTOS-CEMENT PIPE - Figure 1

     Asbestos-Cement pipe was first manufactured in  the early 1900's  in Italy,
and introduced to the North American Market in 1931.  This pipe  is a  mixture
of portland cement and asbestos fibers.

     In the manufacturing process, controlled amounts  of these materials  are
blended with water.  The slurry that is formed is  transferred under pressure
onto a mandrel.  The mandrel is removed when the pipe  is partially cured.  An
intermediate curing is followed by autoelaving (steam  curing for 10 hours  at
180°F).  In Europe and Mexico water cure is used in  lieu of  autoclaving.   Tests
have been conducted proving that autoclaving produces  a product  that  is chemic-
ally more stable than water curing, making the autoclaved asbestos-cement pipe
much more resistant to sulfate attack and more resistant to  soft water deterio-
ration because most of the free lime in the cement has been  hydrated.

     Only three companies manufacture asbestos-cement  pipe  in this country.
Two companies make it in sizes ranging from 4 inches to 24  inches in  diameter
and one company makes it in sizes ranging from 4 inches to  42 inches  in  diameter,
All three companies make two types of asbestos-cement  pipe,  pressure  distribu-
tion or "Class" pipe and Transmission pipe.  The "Class" pipe is made in three
classes 100, 150, 200 psi and the transmission in nine classes  covering a range
of pressure from 25 feet (11 lb/in.2) to 800 feet (346 lb/in.2)  of head.   The
class pipe has much greater safety factors than does the  transmission pipe and
is not as competitive pricewise.

SERVICE DESIGN OF ASBESTOS-CEMENT PIPE

     The Service has its own pipe design standards for most of the pipe that  it
uses as alternatives in its specifications.  The Service designs for asbestos-
cement pipe were developed in conjunction with the asbestos-cement pipe indus-
try and the ASTM (The American Society for Testing and Materials)  C-17
Committee.  The Service's standards are very similar to ASTM's Standard
Specifications for Asbestos-Cement Transmission Pipe No.  C668, except the
Service includes a selection table.  These designs are based upon  the com-
bined loading theory, developed by the late Professor W.  J. Schlick  of Iowa
State College.  The parabola in Figure 2 represents the relationship at  the
point of breaking between internal pressure and external load under  three
edge bearing.
                                     141

-------
                       TAPERED SURFACE -^
JS
N)
JOINT  DETAIL
                                                            ROUND  RUBBER  GASKET
                                                            (BELOW COMPRESSED)
                                                       KEASBY and MATT I SON  TAPERED RING
                                                         JOHNS -MANVILLE V-RING
                                                          RUBBER  JOINT  GASKET
                                 Figure 1.  Asbestos-cement pipe.

-------
OJ
                                              SCHLICK FORMULA
                                                w=
                  EXTERNAL CRUSHING  LOAD
                           lb/linear ft.
                      Figure 2. Asbestos-cement pipe design.

-------
     The equation  (Schlick's formula) for this load/pressure parabola is ex-
pressed as:
                                 w - W  J
                                            p

where P = ultimate hydrostatic pressure with no external crush load, in psi.

      W = ultimate crush  load with no hydrostatic pressure, in Ib/lin ft
          equal to 3-edge bearing load equivalent.

      p = hydrostatic pressure including safety factor, in combination with
          w which will  cause failure, psi.

      w = crush load including safety factor, which in combination with p
          will cause failure, Ib/lin ft in 3-edge bearing test.

Once the unloaded bursting pressure of the pipe and the ultimate crushing load
have been determined, combined loading theory determines the rest of the curve.

     Listed as follows  are the other pipe options that the Service included in
its specifications for  pipeline conveyance and distribution systems:

     Concrete Pressure  Pipes - Figure 3

          1.   Reinforced Concrete  (Bar pipe)

          2.   Reinforced Concrete Cylinder Pipe

          3.   Monolithic

          4.   Noncylinder Prestressed Concrete

          5.   Embedded Cylinder Prestressed Concrete

          6.   Lined Cylinder Prestressed Concrete

          7.   Pretensioned Concrete Cylinder

     Steel and Iron Pipes

          8.   Steel pipe - Mortar lined - Various types of coatings

          9.   Ductile  Iron

     Plastic Pipes

         10.   Reinforced Plastic Mortar  (RPM)

         11.   Reinforced Thermosetting Resin  (RTR)

         12.   Poly Vinyl Chloride  (PVC)

                                     144

-------
Oi
TYPE OF PIPE
Reinforced Concrete
(Bar Pipe)
Reinforced Concrete
Cylinder Pipe
Non-Cylinder
Prestressed Concrete
Embedded Cylinder
Prestressed Concrete
Lined Cylinder
Prestressed Concrete
Pretensioned Concrete
Cylinder Pipe (P.T.)
STEEL
CYL.

X

X
V
X
1
X
WON-
CYL.
X

X
	

MILD
REINFORCING
BAR
X
X



X
HIGH
STRENGTH
WIRE


X
Wrapped on
Con_c_peteJ)ore_
X
X
DESIGN
BASIS
Rigid
Rigid
Rigid
Rigid
Rigid
"Rigid"
Flex.
                                 Figure 3.  Types of concrete pressure pipe.

-------
     The above listed pipe options cannot all be used as substitutes, because
of the manufacturer's size and head class restrictions.

     The following  is a description of  these pipe options, which includes the
design and manufacturing parameters of  each type of pipe:

REINFORCED CONCRETE PRESSURE PIPE

General

     Reinforced  concrete pressure pipe  is furnished in sizes from 12-inch diam-
eter on up.   The largest the Service has installed has been 132-inch diameter
(11 feet), but industry has provided up to 216 inches (18 feet) for some power-
plant cooling lines.  It can be provided in pressure classes up to 150 feet
of head (65 lb/in.2) and for burial depths up to 20 feet.  As such, it is
competitive with A/C pipe only in sizes from 12 to 36 or 39 inches in diameter
and low head  classes - 150 feet and less.

Joints

     Reinforced  concrete pressure pipe  is normally supplied with integral
bell and spigot  joints utilizing a rubber gasket to obtain watertightness.
A double spigot  joint with a steel coupling sleeve can also be furnished.  The
most common configuration which has been supplied on Service projects incor-
porates a gasket groove formed in the spigot of the pipe as shown in Figure 4.
The Service terms this configuration a  "Type R-4" joint.

Manufacture

     The two  common methods for producing concrete pressure pipe are by ver-
tically casting  or  centrifugally casting processes.  For vertically cast pipe,
the concrete  is  introduced at the top of the form, and vibrators attached to
the outside of the  forms insure solid dense concrete.  In the centrifugally
cast process, the forms are spun fast enough to hold the concrete in place by
centrifugal force.  "Knockers" hitting  against the outside of the spinning
form provide vibration.  Free water in  the concrete mix is forced to the  .
inside surface by the centrifugal action where it is blown out one end of the
form.  As a result, the water-cement ratio of the final concrete mix is quite
low, and the  initial set time is shortened.

     Most concrete  pipe producers attempt to get a 1-day turn-around with their
forms.  To accomplish this, an overnight cure using steam or high temperature
moist heat is provided.  After the forms are stripped, the curing is continued
until the concrete  has gained sufficient strength for handling.

     Wall thickness of reinforced concrete pipe are generally approximately
1/12 of the diameter of the pipe for the larger sizes and vary down to a
2-inch minimum thickness for the smaller sizes.

     Reinforcement  is ordinary concrete reinforcing steel usually formed into
circular cages.    Only one cage is used  in 24-inch pipe and smaller, either
one or two cages  (providing an inner and outer layer of reinforcement) can be

                                      146

-------
       Steel  Reinforcing  Cages
JS


"SJ

                                                         Rubber Gasket

'''''-'
                                                            ^^  •  • • . • • ^* • *   * * . •   •  • * • • •  • •
                                                            • .  • • . .  • . -0. •.••..'. 'Q .'.•-.. .0.
                                                            •"•'•».•."•  •  •••-.*  . • .' •  • . • .

                                                            •'•';•'••'•':'•'••• '••'•"-   "^
                                                            •V /ta •-.•fa-.-9; .;®.-A-.ej-.-.t2|. :..^..-

                                                            •  • .  •  • . . "*^ • .  .  • .  « . • .  . •*•< . . ."
                       Figure 4.  Reinforced concrete pressure pipe  (bar pipe).

-------
used in 27- to 36-inch  sizes, and  two cages are used in pipe larger than
36-inch diameter.

     As an alternative  to  two layers of reinforcement, one cage formed in an
ellipse can be used  in  pipe  from 18 to 72  inches  in diameter.  With the ellip-
tical shape,  the reinforcement  can be located within the pipe wall so that it
is at the inside face at the top and bottom of the pipe and at the outside face
at the sides  of the  pipe in  order  to accommodate  the tensile stresses result-
ing from the  bending moments which occur at these locations when the pipe is
loaded.  Use  of elliptical reinforcement requires the cage to be accurately
oriented in the forms at the time  of manufacture  and the location of the field
top be permanently marked  on the pipe unit.  At the time of installation, the
contractor must then install the pipe so that the field top of the pipe unit
is on the vertical center line of the pipe, with a maximum allowable deviation
of 10 degrees from the  vertical.  Elliptically reinforced pipe just does not
work very well if it is laid on its side.

Design
     *•
     Reinforced concrete pressure  pipe is  designed as a rigid structural ring
which transmits the  applied  loadings down  through the pipe wall into the
foundation soil.  As such, the  pipe is weakest when subjected to a line load-
ing on top and a line reaction  on  the bottom and  is strongest when subjected
to a uniform  radial  loading  all around the pipe,  such as an external pressure.
The installed pipe is subjected to a combination  of loadings instead of the
idealized loadings just described.  The soil above the pipe applies varying
loads to the  pipe which are  assumed to act radially over the top and sides of
the pipe, the dead load of the  pipe itself are vertical forces acting down-
ward, the weight of  the water inside the pipeline applies forces acting radially
outward; and'  hydrostatic pressure  inside the pipe results in uniform radial
forces acting outward:  The  reaction force from the supporting foundation soil
depends entirely on  the construction procedures used at the time of installa-
tion.  As stated previously, a  line reaction is a severe loading condition,
and the pipe  is much stronger if the reaction can be spread out over a par-
ticular area  at the  bottom of the  pipe.  The angle at the bottom of the pipe
over which the loads are transmitted from  the pipe wall down into the founda-
tion soil is  termed  the "bedding angle," with a zero degree angle representing
a line reaction.  As an economical compromise, the pipe for Service projects
is designed for a bedding  angle of 90 degrees.  To ensure that this angle is
obtained, our specifications require select material to be placed under the
haunches of the pipe and up  to  a height of three-eights of the pipe O.D.
This material must be compacted to 95 percent of  standard Proctor density
in order to provide  the necessary  support  for the pipe.

     Analytical studies have been  performed to derive the mathematical coeffi-
cients by which the  internal moments, thrusts, and shears in the concrete pipe
wall can be obtained for the various loading conditions.  Once these are known,
ultimate strength reinforced concrete theory is used to obtain the required
wall thickness and amount  of reinforcement.
                                      148

-------
PRETENSIONED CONCRETE CYLINDER PIPE (PT)

General

     Pretensioned concrete cylinder pipe  is furnished in 10-inch through 54-inch
diameters, pressure classes up to 700 feet of  head (300  lb/in.2),  and for burial
depths up to 20 feet.  It is very competitive  with A/C pipe  in  sizes  larger
than 24 inches and in the higher pressure classes.

Joints

     PT pipe utilizes what the Service terms an "R-2" type of joint.   This
joint incorporates a rubber gasket contained in a formed groove in a  steel
spigot ring.  See Figure 5.  The rolled steel  shape from which  the spigot ring
is formed is termed a "Carnegie" shape.  The steel bell  ring is a rolled flat
plate properly sized to mate with the spigot ring.   Tolerances  in this type
of joint are extremely close with the difference in the  circumferences of
the outside of the spigot ring and the inside  of the bell ring  being  less
than 3/16 inch.  Nevertheless, with the smooth steel surfaces in the  joint,
there is little or no tendency for the gasket  to fishmouth,  and there are
very few construction problems associated with this type of  pipe.

Manufacture

     Forming the steel cylinder is the first step in the manufacture  of PT
pipe.  This is normally done by rolling a continuous sheet  of flat steel plate
into a helix and automatically butt welding the edges together.  The  resulting
helically welded cylinder is then cut to  the proper length,  and the spigot and
bell rings are welded on.  At this stage, each cylinder  is  hydrostatically
tested at a pressure which stresses the steel  to 20,000  lb/in.2.  At  this pres-
sure any defects in the welds are readily apparent and are  repaired by manual
welding.  After hydrostatic testing, the  mortar lining is applied to  the in-
side of the cylinder by centrifugally spinning and either steam or water cured
to obtain its design strength.  Steel reinforcing rod is then wound around
the cylinder under a prestressing tension of 8,000 to 10,000 lb/in.2, and the
pipe unit is completed by the application of a mortar coating on the outside
of the reinforcing rod.

Design

     For design purposes, PT pipe is divided into two categories.  Eighteen-inch
diameter and smaller pipe is considered to be rigid, and the mathematical
coefficients for the moments, thrusts, and shears are used based on a  90-degree
bedding angle as for reinforced concrete pipe.  Pipe larger than 18 inches is
considered flexible and moments and thrusts are determined using beams on
elastic foundation theory and considering the pipe to be supported for the
full 180 degrees on the bottom.  After moments and thrusts are  determined,
the design proceeds according to ultimate strength theory for reinforced
concrete.  The steel material for the cylinder and the reinforcing rod wrap
is specified so that the cylinder will have a lower yield strength than the
rod wrap, and because of the effect of the initial prestressing force, failure
of the pipe will occur with the cylinder and rod wrap at their  respective
yield strengths and the mortar lining at its ultimate compressive strength.

                                      149

-------
in
O
             Rod Reinforcement
                  Grout Placed After
                     Instal lation
      Steel Cylinder-1  Steel Spigot Ring J
                            Rubber Gasket
Steel Bell Ring

   /-Cement-Mortar Coating
    L
   Cement-Mortar or
     Concrete Lining
Cement-Mortar Placed
   in Field
                        Figure 5.  Pretensioned concrete cylinder pipe.

-------
     To provide the full 180-degree bedding consistent with the beams on elas-
tic foundation assumption, the soil backfill under the haunches of  the pipe
and at the sides of the pipe up to a depth of 0.7 times the pipe outside diam-
eter is specified to be compacted to 95 percent of Proctor density.

DUCTILE-IRON PIPE

General

     Ductile-iron pipe is furnished in diameters from 3 inches through 54 inches
and for pressure classes up to 1,000 feet of head (450 lb/in.2) including
transient surge pressures.  When installed in a very good trench laying
condition, the pipe can withstand burial loads exerted by from 55 to over
100 feet of earth cover, depending on size.   Although somewhat more  expensive
than A/C pipe, some economics can be achieved with ductile-iron pipe by
relaxing some of the trench installation requirements.

     Being a metal product, due tile-iron pipe is subject to electrolytic corro-
sion when installed in areas where soil resistivity values are low.   In these
areas, cathodic protection must be provided which would entail electrically
bonding the pipe units together by welding a jumper across each joint.  In
many instances, providing test stations to monitor the pipeline may  be suffi-
cient, but in severe, situations an impressed electrical current may  be required.
Additional corrosion protection is provided by normally installing the pipe
with a polyethylene wrap on the outside of the pipe.

Joints

     For irrigation and long water supply pipelines, ductile-iron pipe is
normally furnished with bell and spigot, rubber gasketed, push-on type joints.
Mechanical type rubber gasketed joints and standard flanged joints can also be
provided for other applications.  In the bell and spigot joint, the gasket
is contained in an annular space in the bell and has a special cross sectional
shape in order to seal effectively agaMnst the smooth spigot end of the pipe.

Manufacture

     Cast iron and ductile iron are essentially alloys of iron containing car-
bon and other chemicals.  The primary difference between cast and ductile iron
is that in cast iron, the carbon occurs as free carbon or graphite in the form
of flakes interspersed throughout the metal.  In ductile iron, the carbon is
in nodular or spheroidal form and more finely interspersed in the metal.  This
change in the graphite form is accomplished by adding, at the appropriate
moment, a charge of magnesium to the molten iron.  The pipe is then centrifu-
gally cast in a spinning mold.  When the molten iron has solidified but  is
still red hot, it is removed from the mold and anneal led for an appropriate
period of time.  When cool, a thin cement mortar lining is applied  to the in-
side of the pipe.

Design

     Since ductile iron is a homogenous material, the design  of  this  type  of
pipe is relatively straightforward and is based on  a  minimum yield  strength in

                                     151

-------
tension of 42,000 lb/in.2.  Ductile iron is considered a flexible pipe although
in the smaller sizes it has significant ring stiffness which is reflected in
the design equations.  The equations also consider the lateral support that
a flexible pipe receives from the compacted backfill soil at the sides of
the pipe when the pipe is deflected under external earth and live loads.
Based on the bending stresses due to external loads and tensile stresses due
to internal pressure, standard tables have been prepared from which the
required minimum wall thickness can be determined for a particular installation.
In the determination of the required wall thickness, a design safety factor of
two is applied to the tensile yield stress and a design ring bending stress
of 48,000 lb/in.2 is used which is considered conservative and appropriate.
The bending stresses are determined considering a maximum design deflection
of 3 percent of the pipe diameter.

REINFORCED PLASTIC MORTAR PIPE (RPM)
REINFORCED THERMOSETTING RESIN PIPE (RTR)

General

     These two types of plastic pipe are composed of fiberglass and polyester
plastic resin.  In addition, RPM pipe also contains ordinary sand as an inert
filler to build up the pipe wall.  RTR pipe, also frequently call FRP for
fiberglass reinforced plastic, contains only glass and resin.  Other types of
resins, such as epoxy and vinyl ester, are also used for these types of pipe,
but due to their expense, they are seldom utilized for irrigation or water sup-
ply pipelines.  RPM pipe is furnished in sizes from 8 inches to 54 inches in
diameter while RTR pipe can be obtained as small as 1-inch diameter.  Although
the Service limits the maximum size for these types of pipe to 54 inches,
industry has the capability of manufacturing these products up to 144 inches
(12 feet) in diameter.  Both types can be provided for pressure classes up to
500 feet of head (220 lb/in.2) and for burial depths up to 20 feet.  As with
PT pipe, these products would be competitive with A/C pipe in sizes larger
than 24 inches and in the higher pressure classes.

Joints

     To date, RPM pipe has only been made with an R-4 type joint, that is,
with the rubber gasket confined in a groove in the spigot.  RTR pipe also is
manufactured with R-4 joints but, in addition, can be made with the gasket
groove in the bell and can also utilize a separate coupling such as A/C pipe.
Figure 6 shows examples of RPM and RTR pipe joints.  With smooth plastic
surfaces, these joints have little tendency to have fishmouth gaskets; how-
ever, liberal use of lubricant during installation is still highly desirable.

Manufacture

     Both types of pipe can be manufactured by either a filament winding pro-
cess or by centrifugally casting.  When centrifugally cast, the fiberglass and
resin (and sand, in the case of RPM) are introduced into a mold which is spun
until the catalyzed resin hardens.  The fiberglass can either be woven glass
cloth put into the mold while at rest or it can be introduced as short chopped
fiber strands about 4 inches long while the mold is spinning.  In the filament

                                     152

-------
                        Y(Min.)'OJOd (Average)
GASKET GROOVE ON SPIGOT iUO  OF PIPE
/>i
r*~,
rt
3
3
;» o. S04 (A
     (b)  GASKET GROOVE IN BELL
                        NOTES A Ua*/mum»20*
                              An ou*si
-------
winding process, ^continuous fiberglass strands are bundled together, passed
through a bath of catalyzed resin, and wound on rotating mandrel which moves
longitudinally past the winding station.

     For RPM pipe, the fiberglass is wound on the mandrel almost perpendicular
to the mandrel, and additional layers of fiberglass, with the strands oriented
longitudinally, are applied to give the necessary longitudinal beam strength.
Sand is added periodically in the process, additional glass is wound on top
of the sand, and a final  sand coat is applied to the exterior surface.

     For RTR pipe, the fiberglass is wound on the rotating mandrel at an angle
of from approximately 57  to approximately 75 degrees with the longitudinal axis
of the pipe.  This gives  the pipe its required beam strength instead of
providing longitudinally  oriented glass fibers.  The actual angle is dependent
upon the relative values  of the required beam strength and hoop strength.

     After winding, both  RPM and RTR pipe units are allowed to cure in an oven
environment until the resin has completely hardened, after which  the pipe
unit is removed from the  mandrel.  With RPM pipe, the spigot is then cast into
the prepared end of the pipe by placing the pipe on end in a heated mold into
which resin is poured.  No fiberglass is included in this operation.

Design

     In these types of pipe, all stresses in the pipe wall are considered to be
carried by the fiberglass only and that the resin only provides water tightness
and that holds the fiberglass in place.  A characteristic of plastic pipes such
as these is that when subjected to a fairly high stress level which is held
constant, the pipe will fail after a particular period of time.  If subjected
to a lower stress level,  it will take a longer period of time for the pipe to
fail.  This strength regression relationship between stress level and time to
failure plots as a straight line on a log-log graph, that is, when log time is
plotted versus log stress, and the mathematical relationship can be determined
through a statistical analysis of data from a long term laboratory testing
program.  From this relationship, a design stress level can be established
which will result in an estimated time to failure which is sufficiently long
so as to ensure that the  pipe will not fail for the life of the project.
(For a typical RPM compound, if the design stress is taken as one-half of the
stress level which will cause failure in 100,000 hours (11.4 years), the
estimated time to failure for the design stress level is approximately 28,000
years.)  The required area of fiberglass is then established for a particular
installation so that this design stress level is not exceeded.

     Both RPM and RTR pipe are considered flexible pipes and, as such, require
well compacted backfill underneath and at the sides  of the pipe to prevent
excessive deflection.  This backfill should be compacted to 95 percent of Proc-
tor density to a depth of 0.7 times the outside diameter of the pipe.
                                      154

-------
POLYVINYL CHLORIDE PIPE (PVC)

General

     PVC pipe ±s furnished in sizes up to 18 inches in diameter and as small as
1/8-inch diameter tubing.  Some manufacturers are in the process of expanding
the range up to 22- or 24-inch diameter, and by this time, some of these larger
sizes may be available.  PVC irrigation pipe has pressure ratings based on
the ratio of the dimensions of the outside diameter of the pipe to its wall
thickness so that pipe with the same dimension ratio will have the same pressure
carrying capability, regardless of size.  Other types of PVC pipe, such as
schedule 40, 80, and 120 pipe, having the same dimensions as the corresponding
iron pipe, are also available.  The pressure ratings of the schedule pipe vary
with the pipe diameter, with the smaller pipe being considerably stronger than
the larger pipe.  With the standard dimension ratios, irrigation pipe can be
obtained with pressure ratings up to 700 feet of head (300 lb/in.  ) and for
burial depths well over 20 feet.

Joints

     PVC irrigation pipe is furnished with either rubber gasketed joints or
solvent cemented joints.  Because of the reliability and ease of installation
of the rubber gasketed joints and because successful solvent welding is highly
dependent upon temperature, humidity, blowing dust, and highly qualified work-
men, the Service requires rubber gasketed joints for PVC line pipe.  The rub-
ber gasketed joints are either of the separate coupling type, similar to A/C
pipe, or else are bell and spigot with an annular space for the gasket formed
in the bell.

Manufacture

     Polyvinyl chloride is a thermoplastic resin.  That is, it can be repeatedly
softened by an increase in temperature and hardened by a decrease in tempera-
ture.  In the highly automated manufacturing process, the raw resin, in powder
form, is fed to an extrusion machine where it is heated under pressure (2,000
to 5,000 lb/in.2) until the resin particles fuze together into a viscous,
plastic mass.  The material is extruded through a forming die which molds it
into a cylindrical shape and then immediately cooled into a solid state by
chilled water.  Since the operation is continuous, the pipe is automatically
cut to length by a moving saw that travels at the same speed as the pipe is
being extruded.  For bell and spigot type pipe, the bell is then formed by re-
heating one end of the pipe to a pliable state, forcing it over a forming
mandrel, and again cooling it to a solid state.

Design

     Thermoplastic compounds, such as PVC, exhibit the same strength  regression
characteristics as the fiberglass reinforced compounds as described under  RPM
and RTR pipe.  Therefore, the design stress level for PVC pipe  is  also based on
the long term strenth of the product as determined by a laboratory testing
program.  The required wall thickness can then be established so  that the
design stress is not exceeded.

                                      155

-------
     PVC pipe is also a flexible pipe' and will deflect tinder external trench
loadings.  Many of the pipe manufacturers recommend compacted backfill at the
sides and up to 1 foot above the top  of the pipe, and we require highly com-
pacted material to 6 inches above the pipe.  In smaller diameters and with
greater wall thickness, however, the  pipe does have significant ring stiffness,
and the pipe can be designed to carry significant trench loads with little
lateral support from the soil at the  sides of the pipe.  This allows relaxa-
tion of the compaction requirements for the backfill soil, resulting in a sav-
ings in installation cost.

STEEL PIPE

General

     Steel pipe is practically unlimited in size and pressure ratings.  The
largest steel pipe the Service has installed for water supply purposes is
96 inches in diameter; however, 40-foot-diameter penstocks for dams and
power plants can be considered as steel pipe.  The service requires steel
line pipe to be cement mortar lined on the inside and coated on the outside
with either cement mortar or coal tar enamel wrapped with kraft paper.  Steel
pipe- is considerably more expensive than A/C pipe but can be used as a very
acceptable substitute.

Joints

     Joints in steel pipe are either  welded or are bell and spigot type with a
gasket groove rolled either in the bell of the pipe or on the spigot end.
Figure 7 shows a typical joint with a gasket groove rolled in the spigot.
Some manufacturers can furnish a joint incorporating a carnegie shaped spigot
ring welded to the steel cylinder.  This joint has a big advantage due to the
stiffness of the ring; however, it is more expensive and seldom done.  Welded
joints are normally butt or lap welded after which the mortar lining and
appropriate coating are placed in the field.

Manufacture

     Steel pipe is manufactured either by helically welding a continuous roll
of steel sheet or by forming the cylinder from flat plate and using longitudinal
welds.  If rubber gasketed joints are being provided, the bell and spigot are
rolled to their appropriate shape, and the cylinder is hydrostatically tested.

     Many of the designs for steel pipe require very little wall thickness,
and the cylinder has a tendency to warp due to the heat of welding.  To elim-
inate this, the hydrostatic pressure  inside the cylinder is raised to stress
the steel slightly beyond its yield point.  This causes the cylinder to round
out, and, because the steel has yielded slightly, to retain its circularity
when the pressure is reduced.  The slight increase in diameter resulting from
this operation is taken into account  when forming the cylinder initially.

     After the cylinder is rounded out, the mortar lining is centrifugally
spun on the inside of the pipe and the appropriate coating applied to the
outside.

                                      156

-------
Grout Placed
After Installation
 Steel Cylinder
Ui
  Cement
  Mortar Lining
          Cement Mortar Coating
             Wire Mesh
              Reinforcement
            r' '•'•'•'	
                 _
          Cement Mortar Placed
          After Installation
        Rubber Gasket
     Figure 7. Steel pipe (mortar lined and coated)

-------
Design

     Steel pipe is designed as a flexible conduit, but its ring strength and
arch strength are also considered.  The design procedure follows that in AWWA
Manual Mil which covers three design cases:

     1.   When the wall thickness and diameter selected to meet pressure
          requirements are such that its ring strength is sufficient
          to carry all external trench loads without deflections greater
          than 2 percent of the pipe diameter.

     2.   When the ring strength is sufficient to carry part of the ex-
          ternal trench loads, but not all of it without undue deflection.
          Some side support must be provided by the backfill soil under
          and at the sides of the pipe.

     3.   When the ring strength of the pipe is so low that it can carry
          very little, if any of the external trench loads without undue
          deflection.  Full mobilization of the passive resistance of the
          soil at the sides of the pipe is required.

     Charts and tables are provided in the manual to determine the allowable
earth and live loads that can be carried by a pipe of a particular diameter
and wall thickness.

     Steel pipe on the majority of Service projects would fall into the third
design category as described above.  In order to ensure the necessary side
support for the pipe, we require the backfill soil to be compacted to 95 per-
cent of Proctor density up to a depth of 0.7 times the outside diameter of
the pipe.

ADDITIONAL TYPES OF PIPE SUBSTITUTES

     The substitute pipes as described in the preceeding portion of the paper
are those pipes that have been thoroughly investigated and have been accepted
by the Service for use in its specifications.  It is not the intent of this
paper to represent that these are the only types of pipe available or the
only ones that can be used.

     Listed as follows are some of the other types of pipes that are presently
being manufactured that could possibly be substituted safely and economically
for asbestos-cement pipe:

     1.   Concrete pressure pipe reinforced with steel wires (fibers)

     2.   Concrete pressure pipe reinforced with fiber glass

     3.   Polyethylene (PE)

     4.   Polybutylene (PB)
     5.   Acrylonitrile Butadiene Styrene (ABS)
                                      158

-------
     It usually takes approximately 5 years of investigations and testing
before the Service will use a new type of pipe as an option in its specifica-
tions.  The purpose of this conservatism is that the Service must be reasonably
sure that the pipe will last at least the length of the repayment contract with
the water districts, which is usually 50 years.

AGGRESSIVE TRANSPORTED WATERS

     Aggressiveness of water transported through Asbestos-Cement Pipe as described
by ASTM C500 Standards is as follows:

     Highly aggressive       pH + log (AH) < 10

     Moderately aggressive   pH + log (AH) = 10.0 to 11.9
     Nonaggressive           pH + log (AH) _> 12.0

where

     pH •» index of acidity (or alkalinity) of the water, standard pH units
     A  - total alkalinity, ppm as CaC03, and
     H  = calcium hardness, ppm as CaCOa

     If the pH + log (AH) is < 10, the water is highly aggressive and some means
must be taken to Insure the integrity of asbestos-cement pipe.  This also
applies to all types of cement mortar lined pipe.  Lining of the inside of the
pipe with an inert material is one solution.  Ductile-iron pipe uses an as-
phaltic seal coat over its cement mortar lining for protection.  Treatment
of the water before entering the pipeline is another solution.

ECONOMICAL ADVANTAGES

     Asbestos-cement has an economical edge over the other types of pipes, for
sizes 6 inches to 24 inches in diameter for the following reasons:

     1.   It costs less to produce because the method of manufacturing
          asbestos cement pipe lends itself to automation and the
          materials used in making the A/C pipe cost less in these
          diameters.

     2.   Asbestos-cement is a rigid type of pipe.  It takes less work
          in installation than does the flexible type pipe because al-
          most half as much compaction is required.  Cathodic pro-
          tection is not needed for asbestos-cement pipe.

     3.   Cathodic monitoring stations are required for all  steel,
          ductile iron, and steel cylinder pipe, which require  all
          joints to be bonded.

     4.   If the soil resistivity is low, less  than 2,000 ohm centi-
          meters, cathodic protection must be included  in the cost  of
          steel and steel cylinder and ductile  iron pipes.

                                     159

-------
     For diameters greater than 24 inches and heads higher than 200 feet, the
other listed substitute pipes compare very favorably or are more economical
than asbestos-cement pipe.

SUMMARY

     1.   The Service has installed an 1,100 miles of asbestos-cement
          pipe during the past 23 years and none has had to be replaced
          because of deterioration.

     2.   Reinforced Concrete, Fretensioned Concrete, Lined Cylinder,
          Steel, Ductile Iron, Reinforced Plastic Mortar, Reinforced
          Thermosetting Resin, and Poly Vinyl Chloride pipes can all
          be competently substituted for asbestos-cement pipe, but are
          not economical substitutions for pipe diameters of 24 inches
          and less.

     3.   New types of pipes are being manufactured that could be sub-
          stituted for asbestos-cement pipe, but usually it takes about
          5 years to investigate and test them before they are accepted
          by the Service.

     4.   Asbestos-Cement Pipe and all cement mortar lined pipe should
          be coated on the inside of pipe with an inert material if
          waters having an aggressive index of less than 10 are trans-
          ported through them.
                                     160

-------
            DISCUSSION ON SUBSTITUTES FOR ASBESTOS-CEMENT PIPE

QUESTION  (Mr. Levy):  You said that you have never had to replace  any AC
          pipe in 23 years of experience.  Can you make similar  claims for
          the other materials that you specified and now use?

ANSWER    (Mr. Warden):  Yes.  We have had to replace some reinforced  bar pipe
          where we have had some expansive soils.   This was probably our
          fault because we may have under-designed it.   We have  had to re-
          place our reinforced concrete pipe and also steel pipe that  had
          rusted out because it did not have cathodic protection.   Now we
          are including cathodic protection on all of our steel  and steel
          cylinder pipes.

REMARK    (Mr. Atkinson):  I am Deputy Executive Director of the American Water-
          works Association.

          I would like to file with the Chairman of the working  group  a
          paper that was developed by our California/Nevada section with
          regard to asbestos-cement pipe.

          I would also like to say that our association has standards  for
          practically all the pipe that is manufactured in this  country,
          particularly pipe that is used in drinking water.

          The Association takes a neutral part on what type is to be used
          and thinks that should be left up to the user based  on the recom-
          mendations that he receives from his engineering consultant  for
          the particular project for which the pipe is to be used.   We do
          feel, however, that regulations that might be issued by the
          Federal government should be based on sound scientific knowledge
          and not mere conjecture that some particular product or process
          may have an adverse effect on the health of persons.

          I think this is very important because one of the reasons for
          this workshop, I think, is for EPA and the Consumer Product
          Safety Commission to try to gather additional information on
          whether or not they are going to apply certain rules and regula-
          tions with regard to the use of asbestos.

QUESTION  (Dr. Millette):  In the Service you apparently make measurements
          of the soil resistivity or corrosion problems of the exterior
          of the pipe.  Do you also make measurements of the water quality
          in terms of corrosion index or other indexes and do those come
          into your specifications at all?

ANSWER    (Mr. Warden):  We actually do make measurements  of  the different
          types of water and the conditions that  the pipe  is  going to be
          laid in.  In fact, in the West we have  a very high  sulfate  con-
          tent where we  lay our pipe and in our concrete  structures we
          require Type 5 cement and we do take readings  to determine  what
                                     161

-------
QUESTION
ANSWER
type of soil our pipelines are going to be put into.  We have
a standard for almost every type of pipe but we also have
construction specifications and in these construction specifi-
cations we will spell out what type of soils the contractor
will encounter.

(Dr. Millette):  What about the type of water that he would
encounter; is that included?

(Mr. Warden):  Yes.
QUESTION  (Dr. Millette):  There are some water utilities in the Northeast
          that require an inner coating on asbestos-cement pipe to possibly
          prevent corrosion problems.  Have you ever specified or used
          coating?

ANSWER    (Mr. Warden):  We have never used linings in the AC pipe.  We only
          had one case that I know of and that was in California where the
          water had an aggressive index of less than 10.  So we actually
          did not put AC pipe in because we felt that the water was too
          aggressive for that type of pipe.  We did use a double cement
          lined ductile iron pipe with an asphaltic seal coat but we have
          never used any linings and I do think that linings are something
          that the AC Pipe Association is going to have to address.
                                     162

-------
                        PANEL ON DEVELOPMENT OF SUBSTITUTES
Chairman:     Richard J. Guimond
              U.S. Environmental Protection Agency
              Washington, D.C.

Panelists:    Mr. Robert Moore
              Elson T. Killam Associates
              27 Bleeker Street
              Milburn, N.J.  07041

              Mr. John Gurtowski
              Materials and Processing Division
              Naval Air Systems Command
              Washington, D.C.   20361

              Mr. Roy Steinfurth
              Insulators Health Hazard Program
              Asbestos Workers International
              Asbestos Workers Union
              1300 Connecticut Avenue, NW
              Washington, D.C.   20036

              Mr. James F. Reis
              Director, Asbestos Policy
              Johns-Mansville Corporation
              P.O. Box 5108
              Denver, CO  80217

              Mr. Barry Castleman, Esquire
              Environmental Consultant
              Box 230A, Valley Road
              Rnoxville, MD  21758

CHAIRMAN RICHARD J. GUIMOND

     The topic for the panel is the Development of Substitutes.  The purpose
of the panel is to discuss the development of substitutes from a variety of
perspectives.  We have people from various organizations and vastly different
interests to consider the development of substitutes, the technical problems,
the economics, the health risk aspects, from the concerns of their individual
responsibilities.

MR. ROBERT MOORE

     The American Society for Testing and Materials is a volunteer, non-
profit organization devoted to the development of product standards and test
methods.  Standard and  test methods  for  asbestos-cement products  are  under the
jurisdiction of Committee C-17, one  of  the  Society's  135 technical committees.

                                     163

-------
     Committee C-17, at present, consists of 59 members.  Seventeen members
are classified as producers; these members have 9 votes, the rest being non-
voting members.  Ten members are classified as consumers or users, seventeen
as general interest members, and five are affiliate members.

     Membership in Committee C-17 includes representatives of producers of
asbestos-cement products from firms in the United States, Mexico and Belgium.
Membership also includes producers of asbestos fibers, producers of cement,
representatives of U.S. government agencies, representatives of State and
municipal agencies, consulting engineers, and contractors.  The voting
strength of the various interests is such that producers of asbestos-cement
products have about one-fifth of the total votes on the Committee.

     Committee C-17 was founded in 1947 when the need for standards for
asbestos-cement products was perceived to be urgent.  The first Chairman of
the Committee was Douglas Parsons of the U.S. Bureau of Standards.

     The Committee meets twice a year in January and June.  Task groups
studying particular problems often meet between the main Committee meetings.
Although business is transacted and problems discussed at the meetings of
the Committee, all questions relating to technical standards are decided by
letter ballot.  The ASTM develops standards by the consensus method.  This
means that basically all interests must agree before an action becomes final.
In addition, the Committee must follow strictly the detailed regulations of
the ASTM which requires that interests must be balanced among producers, users
and general interests, that a satisfactory percentage of ballots must be
returned, and that any ballots which contain negative notes must be discussed
and appropriate action agreed-upon.

     Committee C-17 includes several sub-committees:

Sub-Committee C-17.01 - Editorial and International

     This sub-committee is responsible for editorial content of standards and
test methods.  In addition, this sub-committee has the function of acting as
the U.S. TAG (Technical Advisory Group) to the Technical Committee 77 of the
International Standards Organization (TC 77 covers international standards for
asbestos fibers and asbestos-cement products).

Sub-Committee C-17.02 - Research

     This sub-committee helps to coordinate and collect new information with
regard to asbestos-cement products and their uses.  The Research Committee
also monitors round robin product tests.

Sub-Committee C-17.03

     This sub-committee is in charge of developing standards for asbestos-
cement building products, including flat and corrugated sheets, insulated
sandwich panels and asbestos-cement shingles.  A major current use for
asbestos-cement sheets is packing for cooling towers.
                                     164

-------
Sub-Committee C-17.04

     This sub-committee develops standards  for  asbestos-cement pipe  including
pipe for sewers, water mains, drainage and  under drains.

     Current activities in Committee C-17 include development of  a recommended
standard for installation of asbestos-cement  sewer pipe.   In addition  to
information with regard to proper installation  of the  pipe to provide  satis-
factory structural and hydraulic performance, the standard will include
information as to proper methods for cutting  and drilling  operations in order
to avoid eventually dangerous occupational  exposure.

     The Sub-Committee on Research has been receiving  updated information on
the Water and Power Resources Services tesing of autoclaved and normal cured
asbestos-cement pipe in sulfate soils and information  on a test program to
develop further information on structural strength of  buried piping  conducted
by Utah State University.

     The standards developed by the Committee include  a list of definitions
peculiar to asbestos-cement products and a  number of standardized test methods
such as tests for crushing strength of pipes, in addition  to product standards.

     Product standards include dimensional  requirements, tests of strength,
and certain chemical tests.  The requirements for  flexural strength, crushing
strength, bursting strength, and joint tightness are based upon  a combination
of requirements for construction use and consideration of  manufacturers'
standards.

     Because of developing concern over the possible effects  of  asbestos
fibers, together with the possibility that  new products having properties
similar to asbestos cement products may be developed,  the Committee is
currently considering changing its scope from "products deriving their essen-
tial properties from a mixture of asbestos and fibers  and cement" to "fiber
reinforced cement products."

     The concensus method of developing standards  provides a forum where  a
broad range of interests can meet and develop standards which are suitable
to all segments of the population.  The procedure of letter balloting means
that those who are not able to attend the meetings can share equally in  the
work of the Committee.  It furthermore means that any additional information
required to come to a position on a given question can be obtained  and a
ballot can be voted in the absence of group pressures.

     The standards are not static; they  are  undergoing  a  continuous process
of change as new information becomes available or the need for new  products
becomes evident.  One example of this is the standard  for transmission pipe.
This standard permits an engineered design of  transmission piping using  pipe
particularly tailored to the hydraulic requirements rather than  the used
standard classes of pressure piping.  In cases where  pressures are  accurately
known or controlled, transmission pipe permits a more economical use of
material.
                                    165

-------
     The committee welcomes wide participation in its work by interested
persons.  The basic requirements for membership include membership in the
ASTM and a knowledge of the field.

MR. JOHN GURTOWSKI

     Pressured by reports of health problems attributed to asbestos, restric-
tions on the volume of asbestos-contaminated air to which personnel may be
exposed, worker unrest, the high cost of making work areas safe and an executive
order to find an alternate material for Chrysotile AAA fiber (available only
from Rhodesia), the Naval Air Systems Command embarked upon a program
directed toward identifying substitute/alternate materials and in replacing
asbestos components with them as soon as their potential for each specific
application can be verified.

     At the present time the Naval Air Systems Command has forty (40) different
types of aircraft in its inventory and the task of identifying each asbestos-
containing component in each type of aircraft and in its weapons and in
finding satisfactory alternate materials for all of them will be a long term
costly effort.

     To expedite the investigation the Naval Air Systems Command has confined
its first efforts to the newest aircraft in its inventory which include the
F-18, F-14, AV-8A, and CH-53E models.  Here action is being taken to identify
acceptable alternate materials as promptly as possible and make them available
as replacements when a shortage of the asbestos components is revealed either
by operating personnel or by the parts manufacturer.  Admittedly, this is
somewhat of a "piece-meal" approach to solving a major problem, but it will,
hopefully, permit the Fleet to keep its aircraft flying while the search for
alternate materials continues.

     To date, we have located and identified a large number of aircraft
components which contain asbestos in various amounts, none of which have been
found to release fibers in any significant concentrations during flight
operations.  Regardless of this non-hazard situation, knowing that the
components may not be available in the future, they have been listed for
replacement with parts containing no asbestos.

     One major concern requiring costly evaluation is the replacement of
asbestos-containing brake linings in aircraft.  Here we are attempting to
substitute carbon linings, however, FAA regulations require a very costly,
long-term qualification test prior to acceptance.  Currently, neither funds
nor aircraft are available to complete such a test.  By using brake linings
containing asbestos, we have replaced very toxic beryllium brakes; however,
if we cannot find a satisfactory substitute for the asbestos fiber, we may
have to go back to the more acutely toxic beryllium brakes on certain high
performance aircraft.

     However, the most serious related problem facing the Naval Air Systems
Command involves finding alternate materials to replace the asbestos
                                    166

-------
containing thermal insulating liners in missiles and rockets.   Little progress
in this area has been made.

     Preliminary funding requirements to conduct an intensive  program to
find acceptable thermal insulating liner materials may exceed  $1 million.
At the present time, that type of funds is not available to us.  In our
search for alternate materials, the Naval Air Systems Command  is evaluating
a variety of materials for specific applications:  steel wool, quartz fibers,
ceramic fibers, graphite, E-glass, S-glass, Refrasil, polyamide fibers,
ground cork, clay, and nylon fibers.  From the results to date it is apparent
that some asbestos containing components, because of their critical appli-
cation in aircraft and missiles may never be replaced.

     One of our major concerns to-date is the great fear of asbestos created
by widespread publicity regarding its potential carcinogenic nature.  Let
me cite two examples:

     The leading edges of helicopter blades are normally protected from sand
and/or rain erosion by strips of titanium or stainless steel.   The adhesive
used to bond the strips to the blade contained 1 percent asbestos which, after
cure, was never touched.  Operators insisted on hazard pay in  using this
material.  In a similar situation, an adhesive containing 6 percent asbestos,
aluminum powder and another filler, was used to detect cracks  in the spars
of helicopter blades.  The material was used in both manufacturing and in
repairing operations.  Shutdown of both operations was threatened by fear of
asbestos exposure.  Fortunately, we were able to find adhesives for these
operations which did not contain asbestos fillers, and work was permitted to
continue.

     In conclusion, we, in the Naval Air Systems Command, hope that no
sweeping directive will be forthcoming in the near future banning the use of
asbestos or setting, exposure limits at such a low level as to make compliance
impossible to achieve.

     Even so, the Naval Air Systems Command will continue its  active program
to find alternate materials as rapidly as possible and will continue to find
reasonable efforts to solve at least a major portion of the asbestos problems.

     In the long run, it is our objective to replace as many  of  the  asbestos
containing components in our aircraft and weapons as possible with  so  called
"safe materials".

MR. ROY STEINFURTH

     While the use of asbestos has been  extremely curtailed in the insulation
industry and consequently  exposure by our members to  asbestos has been
drastically reduced, we are now, however,, experiencing an increase in
exposure due to renovation work, maintenance, asbestos removal and
demolition.
                                     167

-------
     We regretfully wish to inform'you, however, that in asbestos removal
and demolition we can expect a great upsurge in asbestos-related disease in
workers not associated with our organization.  This is due to unscrupulous
companies, industries and contractors using non-skilled, low-paid employees
for asbestos removal, and also using unregulated dumping sites.  Also many
removal and demolition sites are in crowded urban areas compounding the
risk of contamination to innocent people.

Substitute Materials

     Statistics show that between 2/3 and 374 of asbestos products manu-
factured in this country are being used in construction.  However in most
of these products, the asbestos is locked or sealed in, and safe work
practices can practically eliminate most dangerous fiber exposures.

     In other types of non-asbestos materials being used, we are starting to
experience a great deal of concern and some health problems.

     1)   Asbestos free calcium silicate — some brands show a rather large
          amount of free silica.  Silicosis could result.

     2)   Man-made fibrous insulation materials such as rock wool, mineral
          wool, slag wool, fibrous glass, Kaowool, and others — we are
          constantly receiving letters and phone calls from our local union
          officers and our members complaining about severe dermatitis, eye
          and ear infections and, of course, many upper respiratory tract
          infections.

     3)   Extruded foam rubber products — exposure to toxic fumes from
          adhesives and also solvents and chemicals used for cleaning hands,
          tools and equipment.

     4)   Various insulation cements used for insulating pipe fittings,
          equipment, pumps, etc. — contain mineral wool.  Portland cement
          and other materials cause severe skin and hand irritation
          problems — very dusty when mixing - protective equipment must be
          used.

     5)   Styrofoam, urethane — require respiratory protection in all
          applications, mixing, spraying and foaming  (.02 P.P.M. to M.D.I.
          (methylene diisocyanate) and T.D.I.'s  (toluene diisocyanate) in-
          dependent fresh air supplied respirator) — emphysema from dust,
          cutting.

     6)   We have in the past and will continue in the future to be exposed
          to hot and cold tar pitches which we use to secure many various
          types of insulation materials to equipment, pipes, tanks, etc.
          We are also using many new types of adhesives, fasteners, electric
          welding devices and other methods.  Many of these insulation
          products are being installed in plants, coke ovens, refineries,
          chemical plants and other factories where a combination of toxic
          or carcinogenic materials may be present.

                                     168

-------
     We strongly believe intensive Impartial independent research should be
conducted on any new insulation product before it is released for manu-
facturing and application.  We in no way desire to be exposed to materials
or methods such as used in the asbestos fiasco.

     As a member of the OSHA Construction Safety and Health Advisory
Committee I was appointed to serve on a special 5-man sub-group to review
the current statistics and regulations and to draft new language that would
allow the existing statistics to be applied to construction.  This deliber-
ation took approximately a year and the finished report is now in the process
of being approved, rejected or modified by the Assistant Secretary of Labor,
Eulah Bingham.  This report will also apply to any future health statistics.
Perhaps between this report and the new OSHA Construction Department led by
Mr. Stephen Cooper and the Toxic Substances Control Act, any new materials
in our industry will be fully analyzed and proper precautions can be taken
preventing any new rash of occupational disease.

     More legislation can and should be enacted and enforced to protect the
working people from the unscrupulous manufacturer or employer who puts
profits ahead of human lives.

MR. JAMES F. REIS

     As was evident from the product sessions and round table discussions
earlier today, one of the major points that industry has tried to convey to
EPA and CPSC in relation to their rulemaking on asbestos and their efforts
to develop information on substitutes is a basic precept of the free enter-
prise system:  that is,

          "If substitutes for asbestos and asbestos products were
          technologically and economically feasible, the market
          would have readily adopted them."

     Incorporated into this. statement are many pressures that  industries
using asbestos have faced over the past ten years.  Among them are:

     1.   the increasing price of asbestos

     2.   the cost of asbestos products vs. substitute  products

     3.   the availability  of asbestos vs. substitute materials

     4.   the cost of meeting existing regulations

     5.   the concerns of industry due to  the uncertainty created by
          regulatory agency action and/or  lack of action

     6.   the concern of industry for the  health of its workers

     7.   the concern of increased potential  liability for users of
          asbestos
                                    169

-------
     8.   the increased cost of insurance

     9.   the increased adverse publicity some of which we feel has been
          unfairly generated by the regulatory agencies

     With all of the above factors serving as incentives for industry to
remove asbestos from its products or to find replacement products, why in
1980 does much of U.S. industry and in fact world industry continue to use
asbestos and asbestos products.

     The answer is three-fold.  First, to date, many substitutes have not
proven to be economically and/or technologically feasible.

     Second, there is a significant body of medical evidence that demon-
strate that asbestos when used properly need not present an occupational
hazard in the workplace nor a hazard to the general public.

     And the third explanation which will be addressed tomorrow and
Wednesday at this workshop is that of all the environmental agents used in
industry today, probably more is known about the health effects of asbestos
than any other product.  Industry, as well as EPA and CFSC, has no desire
to manufacture products that in many cases are more expensive and may exhibit
poorer performance, just to find out that these products may present a long
term adverse effect on the health of workers or the general public.

     A case in point is the introduction by DuPont in the early 1970's of
a product called "Fybex", a potassium titanate fiber promoted as a replace-
ment for asbestos in plastics and friction materials.  I have never seen an
estimate of the cost of the research work done by industry in evaluating
this material as an asbestos substitute, but it would probably be conserva-
tive, based on the numbers shown by Mr. Brunhofer this morning, to talk in
millions of dollars.  In 1974, DuPont withdrew this material from the market
because initial testing indicated it could present a health hazard to humans.
A laudable move on the part of DuPont; but a real life example of the
problems that must be anticipated in the search for substitutes for asbestos.

     The asbestos industry has made a conscientious effort to categorize
asbestos products in order to identify those products which can be used
safely and those products which present the greatest potential for un-
controlled release of respirable asbestos.  The product categories the
industry adopted are:

     Encapsulated - Those products which during any reasonable foreseeable
     use do not release fibers in concentrations in excess of the mandated
     OSHA limits.  In many cases fiber release from these products is
     below detectable limits - that is, below 0.1 f/cc.

     "Locked-in" - Those products which do not release fibers in concen-
     trations in excess of the mandated OSHA limits when fabricated and
     installed using proper work practices and/or tools.
                                    170

-------
     Friable - Those products which can release fibers in excess of the
     mandated OSHA limits during routine handling and use.

     It is in the friable category of products where Johns-Manville has
expended its efforts to develop substitutes and where we feel the
substitute approach is the best solution to eliminating potential hazardous
exposures.

     Today, all calcium silicate block and pipe insulation produced by
Johns-Manville does not contain asbestos.  Nor do any of our insulating
cements.  As a supplier of asbestos* we discontinued the sale of asbestos
to the joint cement industry in 1976 and in some cases worked with the
manufacturers to assist them in finding substitutes.

     It is rewarding to see that EPA and CPSC have chosen to devote half of
this workshop to the health aspects of substitutes.  The asbestos cement
pipe industry, in particular, has been extremely concerned with EPA's
hesitancy toward taking a balanced approach to studying the health risks
associated with all types of piping materials used for potable water
supplies.  Despite a significant body of evidence indicating that there is no
danger to health from drinking water transported through asbestos cement
pipe, EPA continues to caution states and municipalities about using this
product.  It would seem reasonable that similar precautions should be issued
for galvanized iron, PVC, and asphalt and coal-tar lined iron and steel
pipe, all of which can contribute minor amounts of known carcinogenic agents
to water supplies.

     All carcinogenic agents conform to certain accepted biological principles.
There is nothing unique about asbestos, except that it is ubiquitous in the
environment and much is known about it.  There is no valid reason, scientific
or otherwise, to treat asbestos differently from any other carcinogen.

     If EPA plans to eventually ban the use of asbestos and encourage or
mandate the use of substitutes for asbestos, then it is logical to assume
that the agency intends to apply this policy to all carcinogenic agents
regulated under the Toxic Substance Control Act.  Any valid economic
evaluation of the impact of this regulatory policy must be extended to
include all carcinogenic agents and not just asbestos.  Any narrower analysis
would be discriminatory.

     It is Johns-Manville's position that products which contain asbestos
in an encapsulated or locked-in form can serve a useful function in our
modern technological society and that these products when used properly, do
not present a hazard to the health and safety of workers or  the general
public.  The many valuable products made with asbestos should not  and  cannot
be regulated out of existence unless there is a demonstrated and overriding
benefit to the public in doing so.
                                     171

-------
MR. BARRY CASTLEMAN

     As you know, most of the products in the asbestos industry are quite
old.  The patents for asbestos insulation and roofing predate 1890.
Asbestos-cement was introduced at the turn of this century.

     Mr. Manville, who ran the Johns-Manville Corporation for the first
quarter of this century, was particularly proud of the fact that he never
spent a dime on research laboratories.

     My own interest in asbestos started in 1970.  I was in graduate school
learning about air pollution.  My background is in chemical engineering.  I
was just looking for something interesting to study, and I tripped over
asbestos.  I took a look at the way they were spraying it on the buildings
for construction, all over the City of Baltimore where I was in school, and
I thought, "Doesn't anybody know that stuff causes lung cancer, and
mesothelioma?  Doesn't anybody know that the neighbors of asbestos factories
get mesothelioma and that the family members of asbestos workers get meso-
thelioma just from the dust that walks home on the guys' clothes?  And people
that live near factories — children that have played on dumps —"  this was
all in the medical literature in 1965.

     This medical literature was based on experiences with the asbestos
products that had long been in manufacture by the companies that were in
that business.  Were they willing to sell less asbestos to save people's
lives?

     The gentleman from the Navy might have more concern if he saw the side
of the use of asbestos that I have seen.  I am involved very often in
litigation involving people who worked in Navy yards, and have developed
cancer and asbestosis as a result of — sometimes just a few summers of
work there.

     While visiting NIOSH in 1974, I was told a curious story.  One of the
inspectors had gone to a Raybestos-Manhattan plant and seen a dry-weaving
operation right in the middle of the floor, and the rest of it was wet
weaving.  The inspector had asked the plant manager how come they do not
shut down that dry weaving operation, it was throwing dust all over the
plant.  He was told, "We have specifications from the Navy requiring so
many threads to the inch, which, in effect, specifies dry-woven asbestos
cloth."

     NIOSH went to the Navy and said to me that they were just told to get
lost when they told the Navy to do something about the specifications.

     By this time I was working for environmental groups, so I dashed off
a quick petition to the Secretary of the Navy, and just to make sure he
read it, I told Jack Anderson a little bit about this story and he wrote
something, too.  This is one of many ways that I learned to operate in
trying to deal with these hazards, as an individual.
                                    172

-------
     The attitudes of the industry have fascinated me.   The only voluntary
removal of asbestos from a single product was children's modeling clay
after Dr. Irving Selikoff found that something like 50,000 pounds of
modeling clay used by the elementary schools of New York was 50 percent
asbestos.  They were making puppets with asbestos, and  it was even in the
Girl Scout Handbook how much asbestos to use to make puppets.

     To this day, the only product that I know being voluntarily written
off as an unacceptable use of asbestos by the asbestos  industry at large
was modeling clay.

     Five years later, in 1976, a woman in West Chester, Pennsylvania, was
making modeling clays for elementary schools, using Johns-Manville asbestos
that she bought from a distributor.  I spent the next several years trying
to convince Johns-Manville not to sell its product through distributors
because Johns-Manville can not tell the distributor whom not to sell it to.
And since only 2 percent of their sales was to a distributor, I thought
they could easily do without it.

     Johns-Manville opposed the ban on drywall spackling, as did the
Asbestos Information Association and Union Carbide, despite the fact that
10,000 tons of asbestos per year was used in spackling  compounds.  The
lungs of drywall workers on X-ray are as damaged as those of insulation
workers, according to recent medical reports.

     As for substitutes, I am extremely pleased to see  that there is now
such an interest in developing substitutes.  I mean money, research and
development resources of some of the largest corporations in this country,
devoted to finding substitutes for asbestos.  This has  led to widespread
substitution of asbestos in insulation; and break-throughs are now being
made in friction products, packings, textiles, plastics, and fiber-cement
products, to name the more prominent cases.  It is about time, and I am
happy to see that.

     I think the most crucial aspect of implementing substitution is the
availability of substitutes.  The EPA cannot write regulations unless
you people come forth with viable, commercial substitutes for asbestos,
with products that are quite reasonably capable of replacing asbestos,
considering the public health hazards of asbestos and the hazards of  the
substitutes.

     I have never heard of a single substitute for an asbestos product  that
could rival asbestos for hazard.  I am sure more needs  to be known  about
that, but we still need to decide what to do today, while we are finding
out.

     My personal hope is that we can prevent, world-wide many needless
deaths from exposure to asbestos.

     One of the people who I am involved with  in  compensation  proceedings
is a woman who worked as a secretary in a plant where  asbestos-cement panels
were sawed up.  She worked two floors below the cutting room of where they

                                     173

-------
sawed up those asbestos panels.  This woman has mesothelioma today.   It
does not take that much exposure to kill.

     Yet today I find near the affiliates in India, of the Johns-Manville
Corporation and British firm Turner and Newall, conditions which you would
not believe, conditions which we thought went out with Merewether's reports
in 1930.  I have pictures of a two-year old child sitting on an asbestos
cement waste dump right in front of his house beside Johns-Manville
affiliate in Ahmedabad.  Houses in the neighborhood are built of asbestos
cement waste, and untreated wastewater pours its opaque burden into the
surface waters of the region.

     After hearing what I have heard today about the availability of
substitutes, I think we are headed toward a tremendous reduction in the use
of asbestos worldwide.  People in a lot of countries are gearing up the
same as we are here.  I think that the United States will probably lead the
way.  Hopefully, Quebec will see the mistake that it is making, getting into
the asbestos business at this time.

     In Ontario, Johns-Manville just shut down a plant making asbestos
cement pipe  when the 170 workers went out on strike.  They said there is
not enough market for it and that they were shutting down other plants in
the United States, too.  This plant in Toronto opened in 1947.  Over the
last 20 years, 120 claims have been allowed for asbestosis and mesothelioma
and around 50 workers have died from asbestos diseases.

     Meanwhile, Quebec is thinking of going into the asbestos business,
nationalizing its asbestos mines and being the death merchants of the
1980's, selling the stuff all over the world.

     The availability of substitutes today convinces me that the use of
asbestos is really going to decline.  It is not something that we have much
longer to wait for; it is really here.  Tou have done a good job, and now
it's EPA's turn.
                                     174

-------
                     DISCUSSION ON DEVELOPMENT OF SUBSTITUTES

QUESTION  (Mr. Gurtowski):  From 1935 to 1943, I was a chemist in the
          American Manufacturing Company.  We manufactured loaded insulation.
          We used from 50 to 70 tons of the material a month.  When I
          checked back several months ago to see how many people had died
          or had cancer, I was quite surprised to find there were two or
          three people.  Most of the people, 'they to^Ld me, died from over-
          smoking.  What had happened to the other 500 people who were
          working in the plant with me?

ANSWER    (Mr. Castleman):  You are a fortunate man and you now have the
          opportunity to provide some protection for people who are
          currently in similar circumstances.  Those circumstances are now
          well recognized to be dangerous.   Statistical studies on the
          population establish that by working in circumstances such as you
          described, you are running a high risk of acquiring adverse
          health effects.

QUESTION  (Chairman Guimond):  I have a question that I would like to direct
          to Mr. Moore, relative to the ASTM (the American Society for Testing
          and Materials) developmental standards.  One of the concerns that a
          few people have expressed to me is that in some cases Federal (and
          other) specifications require that varied amounts of asbestos be in a
          product, whether or not the product really needs it for performance
          purposes.

          First of all, I would like your comments on these specifications, and
          second, to what extent do you see the performance standards, either
          standards by ASTM or other types of organizations, being useful in
          determining whether or not a substitute will perform adequately.

ANSWER    (Mr. Moore):  Number one, my recollection is that ASTM
          specifications do not specify formulation of the products.  They
          specify performance of the product.  I am also of the under-
          standing that it is now Federal policy that such a standard be
          used wherever practical.  The Federal government is using ASTM
          standards in most cases.

QUESTION  (Chairman Guimond):  I was asking a broader question, and not
          necessarily about ASTM; that is, do you know of other kinds of
          stipulations such as Federal specifications that might be any
          hindrance?  Or secondly, do you think that we should broaden
          standards into areas where they do not currently exist,  so  they
          will help us to determine equivalence for performance?
                                   175

-------
ANSWER    (Mr. Moore):  I am not really aware of any such standard existing.

          With regard to general performance standards, the standards that
          are now developed do provide for specific performance for various
          types of materials and are significantly different depending on
          the characteristics of the materials, such as plastics, in-duct
          wiring, reinforced concrete, and asbestos-cement.

          It is very difficult to come up with an overall generic specific-
          ation that will cover all circumstances.  It requires experience
          in the field as to the performance of the parts of the various
          products, and the particular conditions requiring one product
          rather than another.  It is very difficult to come up with an
          overall standard.

QUESTION  (Mr. Gurtowski):  In many areas, we are concerned about thermal
          insulation, should we worry about exposure to various solvents
          in the chemical?  And how is ASTM going to handle that particular
          problem?

ANSWER    (Mr. Moore):  These standards are developed by committees of
          people who are familiar with the characteristics of the various
          products, so that information is, hopefully, put together in
          development.

QUESTION  (Chairman Guimond):  Mr. Gurtowski, you were talking about the
          transition to substitutes in aircraft in the Naval program.  Are
          you doing anything from the standpoint of first establishing
          what performance you need and then searching for substitutes?

ANSWER    (Mr. Gurtowski):  Yes, we look at- the environment the product is
          exposed to (temperatures, solvents, fluids) and then try to
          find a substitute that has the same physical and chemical
          properties.  The substitute we find will have to have exactly the
          same physical properties of the material we intend to replace.

          In particular, one formulation that contained 6 percent asbestos
          was looked at in the aircraft where the temperature did not
          exceed 200°F.  The specifications were very low, so through a
          series of experiments, we developed a new formulation.  In that
          particular case, it was relatively simple.  But for instance, if
          we have to protect the pilot from a fire with temperatures that
          will exceed 2,000°F what substitute are we going to use?  The
          other thing we worry about is if we use glass, it can break up,
          and be inhaled into the lungs and could be just as dangerous as
          asbestos fibers.  This gives you an idea of some of the things
          we have to do.
                                   176

-------
          I have one problem now where we have  an asbestos  cloth  that  is
          impregnated with neoprene rubber.   In, this  particular case we
          depend on the neoprene rubber to get  overheated,  char,  and act  as
          a thermal insulator,  in addition to giving  us  the protection
          against fire.  We have hundreds of materials which protect our
          aircraft, such as polysulfide, polyurethane sealant, and others.
          Many of these contain some form of asbestos, whether in a
          powdered form or in various lengths.   The asbestos provides  needed
          properties; at the same time the substance  gives  us the water
          proofing we need to make sure that our aircraft flies safely with
          our weapons systems.
          In missiles, the temperatures quite often exceed 2,000 F,  even
          though it is just for a few seconds.   What material  are we going
          to use?  Glass will melt,  other organic materials  I  do not think
          will work either.  We are  not giving up the  search for a  substi-
          tute, but the understanding is that we are not  going to eliminate
          asbestos altogether.  That is something that will  never happen.

QUESTION  (Mr. Castleman):  This question is  directed  to  Jim Reis.   I would
          like to get a list of inappropriate or unfit uses  of asbestos
          from Johns-Manville, or from any other company.  I was told by  your
          world fiber sales chief three years ago that such  a  list  was being
          developed, but I was never able to  obtain it.   I presume  the sale
          of fibers for uses that you consider off  limits as well as the  use
          of your own fiber occurs.   Does this apply world-wide or  just in
          a particular locality?

          Lastly, if you have information on  the vinyl chloride that leaches
          from PVC pipes into drinking water, which the  EPA  ought to know
          about in evaluating its alternatives to asbestos cement,  will you
          please submit that information.  I  would  assume that you  have  done
          some testing and I am sure that EPA would be interested  in seeing
          what you thought.

ANSWER    (Mr. Reis):  As far as appropriating uses are  concerned,  there
          have been several presentations given by  Johns-Manville people that
          identified a number of appropriate  uses.   We looked at  each of the
          categories and made a conscientious effort to  try  to eliminate sales
          to those categories which we identify as  inappropriate.

QUESTION  (Mr. Castleman):  What are the categories that were inappropriate?
          There could not be too many of them; can you remember?

ANSWER    (Mr. Reis):  I have listed several of them here and I could probably
          go on.  I do not have any desire to list them right now.

QUESTION  (Mr. Castleman):  Well, what are they:  insulation, spackling  com-
          pound, children's clay, hair dryers?  What else is an inappropriate
          use of asbestos?

QUESTION  (Chairman Guimond):  Mr. Reis has  indicated they  are developing
          substitutes in  the areas where  they feel  asbestos was inappropriate.
          Is it implied that you are or are  not  developing  substitutes or
          considering substitutes in the  areas where  you have locked-in
          fibers or the encapsulated fibers?

                                      177

-------
ANSWER    (Mr. Reis):  That is a particular point I did not mention, but
          I think it is common business sense.  I do not think there is
          anyone in this room who uses asbestos today who is not looking at
          potential substitutes.  A hundred years ago, asbestos was not a
          particularly common product in industrial use.  It evolved over
          that period of time; it has become very popular, and like many other
          products in industry, we did not foresee the possibility that its
          use would become a'lot less than it is today.  So we continue to
          look at substitutes.  Obviously, Johns-Manville, as any other
          company here that uses asbestos, is aware of the government
          regulatory actions, and we will look at substitutes and evaluate
          them from our viewpoint.

QUESTION  (Mr. McCarthy):  I am with Minerals Week.  I would like to address
          this question to the representative from the asbestos workers.

          What are your feelings about being somewhat of a guinea pig for
          potential health effects from replacements for asbestos.  Are you
          actively involved in ensuring that the laboratory tests meet speci-
          fications before you start using those kinds of materials?

ANSWER    (Mr. Steinfurth):  We do have many materials analyzed by a well
          known firm.  If I mentioned the name, you would agree that they have
          a good reputation, both in industry and government.  I happen to
          have two sons who are asbestos workers.  They have been working
          with a particular fibrous product in a nuclear energy plant.  They
          have been working seven days a week in a so-called spread room,
          cable room and so forth.  They came to iny house yesterday and I
          could not recognize them because their eyes were almost closed
          and their faces looked like they had the measles.  I guess you
          know now that they were working with Kayo wool.  They were laying
          it very gently in the cable area.

          Of course the temperature in this spread room runs about 105 to
          110°F.  They did not have the proper safety equipment, respiratory
          equipment and so forth.

          We have also found that some protective clothing, which many people
          call "paper coveralls," should not be worn in heated areas because
          they induce heat stress and eventually heat prostration, or heat
          stroke.
          I am sorry, I missed parts of your question, please state it again.

QUESTION  (Mr. McCarthy):  Basically, I am looking for what the asbestos
          workers might have available to them, to ensure that that kind of
          result does not occur to workers in general.  Is there a lobbying
          effort on your part?  Is the government actively soliciting some
          prerequisite regulations on your behalf before it goes into general
          use?  Is there any intercommunication between you and specific
          corporations that are looking at asbestos and categories they have
          considered inappropriate uses?

                                      178

-------
ANSWER    (Mr. Steinfurth):  We do not have that much involvement with some of
          the current produces.  In fact, this is supposed to be covered
          under the Toxic Substance Law—let us leave it that way.  Up to
          date, you know ae well as I do, the law has not worked the way it
          should have worked.  We have to depend on ourselves and independent
          scientists.  We, in our organization, feel we can no longer take
          the word of any industry-oriented scientist, after the problems we
          have encountered with asbestos.  We do analyze products, see what
          they are made of, get the opinion from not only the person who
          analyzes the products, but also from different authorities, such as
          Dr. Selikoff and Dr. Cooper, who both do work for us and are able
          to help us immensely.

QUESTION  (Mr. McCarthy):  If the workers find themselves in these kinds of
          predicaments and if they really can not judge the effect of the
          substitute without, perhaps, lengthy exposure experiments, what
          state does the consumer find himself as far as exposing himself
          to asbestos and to what extent can he approach the government or
          industry, or, perhaps, an organized labor union to ensure his own
          safety?

          I mean, asbestos receives enough publicity that people are coming
          to grips with it; consumers are looking for labels in areas before
          they replace asbestos tiles, tools, etc.  What about replacement
          parts?  Are consumers being led to believe that they are safe when
          actually we have no evidence to the fact?

ANSWER    (Mr. Steinf urth):  What you say is true.  Some consumers are led
          to believe that some products are dangerous.  We have had problems
          with some products.  I have to put it very gently and say that if
          we do have a problem and the contractor or owner does not wish to
          cooperate, we have methods to make them cooperate.

REMARK    (Mr. Gurtowski):  We have activities that we do at the Navy
          Environmental Health Center related to all of these organic materials
          to ensure that the workers are protected.

          One of the things we find to be the worst culprit, as  far  as  toxicity
          is concerned, is that a man becomes so familiar with a  product
          that he gets careless.  We have had several Fh.D.'s who had  to
          retire because of exposure.  One man should have known  better, but
          he had worked with the material for so long that he got a little
          careless and he paid for it.
                                      179

-------
                        ROUNDTABLE DISCUSSION SESSIONS


     The roundtable discussions were provided to give all participants a chance
to supply information on technical and economic substitutes for asbestos to
EPA.  The roundtables discussed asbestos substitutes for eight categories:
friction materials, gaskets and packings, reinforced plastics, flooring,
paper and roofing products, textiles, asbestos-cement sheet, and asbestos-
cement pipe.  These roundtable discussions were held concurrently from 3:30 -
5:30 p.m., the first day of the workshop.

     A list of general questions about asbestos substitutes for asbestos was
distributed to all participants to help guide the discussions, followed by  a
similar but more detailed list for each product category.  These questions
and the summaries of the roundtable discussions follow on the succeeding pages.

        1.  What are all of the uses and applications in this product
            category?
        2.  What fibrous or product substitutes exist for these
            applications, products, and uses?

        3.  What are the technical performance characteristics of the
            substitutes in this category?

        4.  What are the lifecycle costs of the substitutes in this
            category?
        5.  To what extent can existing capital equipment be used to
            produce substitute materials or products?

        6.  Would energy requirements be changed substantially by switching
            to production or use of the non-asbestos material?

        7.  What are the performance standards or product specifications
            required of a substitute?  Would any of these standards be
            unnecessary if substitute materials were used?

        8.  What research and development is underway in this product
            category?
        9.  Identify any health and environmental effects_of  the materials
            used to substitute for asbestos in this product  category. ~ .
                                      181

-------
SUBSTITUTES FOR ASBESTOS FRICTION MATERIALS
 1.  What  are  the basic  ingredients  used in nonasbestos  disc brake  and
    drum  brake  lining formulations?  Of particular  interest are  the
    materials used to substitute for asbestos.  What  are the  physical
    characteristics and size distribution of  fibers used to substitute
    for asbestos?           ;

 2.  What  are  the performance characteristics  and  the  problems associated
    with  the  use of substitute products for drum  brake  linings contain-
    ing asbestos?   Do the non-asbestos pads provide adequate  performance
    in the categories of lining wear, noise,  wet  recovery, etc?

 3.  What  non-asbestos friction materials are  available  for applications
    other than  in  automobiles and light trucks  (aircraft, heavy  duty vehi-
    cles, etc.)?

 4.  What  problems  hinder the commercial utilization of  non-asbestos drum
    brakes?  Estimate research and  development  costs  and time for  develop-
    ment  of commercial  non-asbestos drum brake  linings.   How  long  did it
    take  to develop non-asbestos disc brake pads?

 5.  If a  new  car is designed to use non-asbestos  disc brakes  are re-
    placement linings for that vehicle also non-asbestos?  What  are the
    problems  associated with providing a replacement  lining tor  a  car
    which has been designed to use  non-asbestos brakes?

 6.  What  mechanisms are there for the transfer  of technology  to  other
    companies who  manufacture brake linings?  If  the  use of asbestos in
    friction  materials  such as brake linings  and  clutch facings  were
    prohibited  how would your company acquire the technology  to  manufac-
    ture  non-asbestos friction materials?

 7.  Identify  any health and environmental effects of  the materials used
    to substitute  for asbestos in friction materials.
                                    182

-------
SUBSTITUTES FOR ASBESTOS GASKETS AND PACKINGS
 1.   The background Information report identifies  two main  types
     of asbestos gaskets:  compressed sheets  and beater-add  sheets.   It
     also states that asbestos packings are  generally made  from yarns
     impregnated with a lubricant,  and that  packings may  either be  leak
     proof (for valves) or permit leaking (for pumps).  What  other  types
     of gasketing and packing materials containing as.bes:tos exist?

 2.   Fiber substitutes for asbestos in gaskets and packings include silica,
     graphite,  and ceramic fibers,  as well as  some synthetic  fibers:
     aramids, Kevlar®, Teflon®, Gylon®, and  Nu-Board.  What other fibrous
     substitutes are available?  What non-fibrous  substitutes are available?

 3.   How do available substitutes perform with respect to 1)  resistance
     to heat, 2) resistance to pressure and  friction  (in  the  case of
     packings), and 3) resistance to chemical  attack?  Do synthetic
     fibers perform better than the natural  (silica or graphite) fibers?
     How do non-fibrous substitutes perform?

 4.   The cost of substitute fibers ranges from .75 to 32  times the  cost of
     asbestos fibers.  However, these are not  lifecycle costs. How do  the
     cost of installation and maintenance frequency influence the lifecyele
     cost of a substitute gasket or packing?

 5.   In the case of substitution of other fibers  for asbestos in gaskets
     and packings, can original equipment still be used in  production of
     the nonasbestos product?  What are the  projected costs of any  equip-
     ment modifications that must be made?
                                                     i
 6.   Would energy requirements be changed substantially by  switching to
     production or use of the nonasbestos material?

 7.   What performance standards or specifications are required of  gasketing
     and packing materials?  Do substitute materials  meet these standards and
     specifications?  Would any of these standards be unnecessary if sub-
     stitutes were used?

 8.   The background information document lists a large  number of non-
     asbestos raw materials from which gaskets and packings may be fab-
     ricated.  What research is planned or underway to  develop addi-
     tional new materials?

 9.   Identify any health and environmental effects of the materials used
     to substitute for asbestos in this product category.
                                      183

-------
SUBSTITUTES FOR ASBESTOS IN REINFORCED PLASTICS


1.   What are all of the major uses and applications in this product
     category?

2.   What fibrous or product substitutes exist for these applications,
     products, and uses?

     We know that glass fibers, carbon fibers, aramid fibers, clay, mica,
     wollastonite, calcium sulfate and talc can be used to replace asbestos
     fiber in phenolic molding compounds and other plastics.  What other
     materials can be used to replace asbestos in these plastics?  We know
     that the types of plastics that are used include phenolics, urea, melamine,
     unsaturdted polyesters, diallyl phthalate prepolymers, epoxies, silicones,
     polypropylene, and nylon.  What other plastics are used to make rein-
     forced plastics?

3.   What are the technical performance characteristics of the substitutes in
     this product category?  Are there any applications for which no sub-
     stitutes have been found?  Have substitutes been found for phenolic
     molding compounds in commutators and rotors for electrical and automotive
     appliances?  Is there data on the long term performance, particularly
     durability, of these and other substitutes?

4.   What are the life cycle costs of the substitutes?  We would like information
     on costs of production, maintenance, and replacement (i.e. product lifetime).
     There can be a rather large variation in cost of filler material for plastics.
     Does this cause any large variations in final product cost?  If so, what
     are they?

5.   To what extent can existing equipment or processes be used to produce
     substitute materials or products?  If existing equipment or processes
     must be modified to accommodate substitute production, what changes must
     be made and what are the costs of those changes?

6.   Would energy requirements be changed substantially by switching to pro-r
     duction or use of the nonasbestos material?

7.   What are the performance standards of product specifications required of
     a substitute?  Would any of these standards be unnecessary if sub-
     stitute materials were used?

8.   What research and development is underway or planned in this product
     category?

9.   Identify any health and environmental effects of the materials used to
     substitute for asbestos in this product category.
                                     184

-------
SUBSTITUTES FOR ASBESTOS IN FLOORING


1.   What are all of the applications and uses of asbestos in this product
     category:  Are there any other types of asbestos containing flooring
     other than floor tile and sheet flooring?

2.   What fibrous or product substitutes exist for these applications, products,
     and uses?

3.   What are the technical performance~characteristics of substitutes in this
     product category?  Are there any applications for which no substitutes
     have been found?

4.   What are the lifecycle costs of substitutes?  We would like information
     on costs of production, maintenance, and replacement (i.e., product
     lifetime).

5.   To what extent can existing equipment or processes be used to produce
     substitute materials or products?  Would new equipment or processes be
     required to produce or use nonasbestos vinyl flooring?  If so, what
     would be the costs of developing the new equipment or processes?

6.   Would energy requirements be changed substantially by switching to
     production or use of the nonasbestos material?

7.   What are the performance standards or product specifications
     required of a substitute?  Would any of these standards be unnecessary if
     substitute materials were used?

8.   What research and development is underway or planned in this product
     category?  When do various companies project that they can develop
     prototype substitute materials?  When do they expect nonasbestos vinyl
     products to be commercially available?

9.   Identify any health and environmental effects of the materials used to
     substitute for asbestos in this product category.
                                       185

-------
SUBSTITUTES FOR ASBESTOS PAPER AND ROOFING PRODUCTS

1.  The paper products that are listed below contain asbestos and have
    multiple uses:
        a.  Flooring felt
        b.  Roofing felt
        c.  Beater-add gaskets
        d.  Pipeline wrap
        e.  Millboard
        f.  Electrical insulation
        g.  Commercial paper
           - General purpose thermal insulation
           - Muffler paper
           - Corrugated paper
        h.  Speciality papers
           - Cooling tower fill
           - Transmission paper
           - Electrolytic diaphragms
           - Decorative laminates
        i.  Beverage and pharmaceutical filters
    Are you aware of any other asbestos-containing paper products?  What are
    they and what are their uses?
2.  The following substitutes exist for the paper products that are listed
    above:
        a.  Flooring felt - potential substitutes that have been studied
            include fiberglass, cellulose, Nomex®, other polymeric fibers.
        b.  Roofing felt - organic felt, fiberglass felt, single-ply
            membrane felt.
        c.  Beater-add gaskets - ceramic, Teflon®, metals.
        d.  Pipeline wrap - saturated fiberglass, plastic tapes, extruded
            epoxys, and resins.
        e.  Millboard - aluminasilicate ceramic fibers and inorganic or
            organic binders, ceramic fiberboards.
        f.  Electrical insulation - aramid paper, ceramic paper.
        g.  Commercial paper - ceramics, cellulose, fiberglass.
                                     186

-------
        h.  Specialty papers

           - Cooling tower fillers - polyvinyl and  polypropylene  plastics,

           cellulose, aluminum,  steel.

           - Electrolytic diaphragms -  Nafion® membrane  cell.

           - Decorative laminates - glass,  ceramic  papers.

        i.  Beverage and pharmaceutical filters - cellulose, fibers,

            diatomaceous earth,  mixed wood  pulp and paper.
    What other fibrous or non-fibrous substitutes exist  for these paper products?

3.  Any number of the following  factors may be considered in evaluating the
    technical performance of these materials:

        •   strength

        •   decay resistance

        •   thermal resistance

        •   sound deadening

        •   water proofing

        •   durability

        •   economy

    How do substitutes for the nine types of asbestos paper products mentioned
    in question #1 perform relative to  the  factors  listed above?   Are there
    any applications for which no substitutes exist?

4.  Based on the background information report, the cost of substitutes seems
    to be greater (up to 10 times) than the cost for asbestos  products
    (except for organic felt used in place  of asbestos roofing felt).  These
    costs, however, are not lifecycle costs.  What  are the costs  of substitutes,
    Including transportation, installation, maintenance and replacement (i.e.,
    product lifetime) costs?

5.  Several asbestos paper products are manufactured using conventional
    paper machinery.  For example, commercial papers, roofing felt, and
    electrical insulation are produced in this manner.  Can substitute papers
    be manufactured using the existing equipment?  Do you foresee any
    additional equipment costs in switching to non-asbestos substitutes?

6.  What additional energy requirements do you anticipate for the production
    of substitute products?
                                     187

-------
7.  One product specification that is consistently mentioned in the
    summary report is "durability."  What is your definition of a "durable"
    substitute?  What other performance standards do you consider to be
    essential?  Are there performance standards for the production of non-
    asbestos paper products?

8.  The summary report indicates that substitutes for the nine groups of
    asbestos paper products either have been or are currently being developed.
    What research and development is planned or underway that may effect sub-
    stitutions for asbestos paper products?

9.  Identify any health and environmental effects of the materials used to
    substitute for asbestos in this product category.
                                      188

-------
SUBSTITUTES FOR ASBESTOS TEXTILES

1.  The three major uses for asbestos textiles are:
    a.  Fire resistant application in
            (1)   welding curtains
            (2)   draperies
            (3)   blankets
            (4)   protective clothing
            (5)   hot conveyor belts
            (6)   furnace shields
            (7)   molten metal splash protection aprons
            (8)   rocket and missile parts
            (9)   ironing board covers
            (10)  theater curtains
    b.  Thermal insulation in
            (1)   pipe wraps for safety protection
            (2)   stress relieving pads in welding operations
            (3)   protective covering for hot glassware utensils
            (4)   coverings for diesel engine exhaust lines
            (5)   flue sleeves
            (6)   braided walls in the construction of steam hoses
    c.  Electrical insulation in
            (1)   wires and cables
            (2)   arcing barriers in switches
            (3)   circuit breakers
            (4)   heater cords
            (5)   motor windings
    Do you have any additional major uses to add  to this  list?
2.  The major  types of substitutes for asbestos textiles  are  fiberglass,
    ceramics,  organics, graphite, carbon, quartz,  cotton,  and special wool
    blends.  Can you add other substitutes  to  this list?
3.  How do substitutes compare to the asbestos use or products in technical
    performance?
    Fire resistant materials:  Which substitutes  are  effective at temperatures
    higher than 1000°F  (540°C)?  Which substitutes are effective at lower
    temperatures?

-------
    Thermal Insulation: Fiberglass is effective at temperatures below 1000°F
    (5AO°C) and ceramics at higher temperatures; however, these materials
    may lack strength.  How important is this quality for thermal insulation
    applications?

    Electrical insulation: Glass and organic materials can be used at lower
    temperatures and ceramic materials and quartz are more effective at
    higher temperatures.  Glass is not suitable in applications where severe
    flexing is involved.  These materials tend to have low conductivity and
    low density.  Please comment.

4.  What are the lifecycle costs of substitutes?  Consider costs of production,
    maintenance, and replacement (i.e. product lifetime).  Are there any
    substitutes which are available but are not yet marketable because of cost?
    Would economies of scale reduce costs enough to make them cost competitive?
    If so, which ones would become cost competitive?

5.  Can substitutes for asbestos textiles be made or used with existing
    equipment and processes?  If changes are required what are the costs of
    these changes?

6.  Would energy requirements be changed substantially by switching to
    production or use of nonasbestos materials?

7.  What are the existing performance standards or product specifications for
    textile applications?  For example, asbestos fire insulation has a UL fire
    rating.  Can substitutes meet the same standards?  Would any of these
    standards be unnecessary if substitute materials were used?

8.  What research and development is underway or planned to effect sub-
    stitution of other materials for asbestos?  To what extent are recently-
    developed or introduced substitutes such as Refrasil®, Thermo-Sil™,
    Zetex™, Nextel® 312, Nomex®, Teflon®, Kynol™, Durette®, P.B.I.™,
    Thermo-Ceram™, Fiberfrax®, Celion®, Celiox™, Alphaquartz, and Norfab®
    being produced and sold in the United States?  How long did it take to
    develop these materials and what were the development costs?

9.  Identify any health and environmental effects of the materials used to
    substitute for asbestos in this product category.
                                     190

-------
SUBSTITUTES FOR ASBESTOS-CEMENT SHEET


1.  The four major types of asbestos-cement sheet (a/c sheet) are

    a.  Flat sheet, used in

            (1) Industrial, commercial, and residential buildings
            (2) decorative paneling
            (3) cooling towers
            (4) laboratory table tops
            (5) ovens, safes, heaters,  etc.

    b.  Corrugated sheet, used in

            (1) electrical equipment as an insulator
    c.  Siding shingles

            (1) industrial and agricultural buildings

            (2) lining for waterways and canal bulkheads
            (3) cooling towers
  «
    d.  Roofing shingles
    Do you have any additional major applications or uses to add to
    this list?
2.  The major types of substitutes for a/c sheet are glass-reinforced
    concrete, cement-wood board, other types of fiber-reinforced concrete,
    and wood products such as hardboard.  Can you add any additional types of
    substitutes for a/c sheet to this list?

3.  What are the technical performance characteristics of the substitutes in
    this product category?

        Glass-reinforced concrete, although its overall strength is high,
        may be weak at high temperatures.  It may also be difficult to
        machine well.  Please comment on any other limitations on the
        performance of glass-reinforced concrete sheet.

        What are the performance characteristics of other substitutes for
        a/c sheet, including cement-wood board, wood products, alumina-
        silica products, and fiber-reinforced concrete?

        For what a/c sheet applications are there currently  no available
        substitutes?  Lab tables and some electrical applications  (which?)
        may be examples of applications for which there are  currently no
        available substitutes.

4.  What are the lifecycle costs of various substitutes for  a/c  sheet?   Are

                                     191

-------
    there any substitutes which are available but are not yet marketable
    because of cost?  Would economies of scale from increased production of
    the substitutes mitigate this problem?

5.  To what extent can capital equipment currently used for a/c sheet
    production be used to produce fiber-reinforced concrete or other sub-
    stitutes for a/c sheet?

6.  Would energy requirements be changed substantially by switching to
    production or use of the nonasbestos material?

7.  What are the performance standards or product specifications required of
    a substitute?  Would any of these standards be unnecessary if substitute
    materials were used?  For example, a/c shingles have a U.L. Class A fire
    rating.  Can substitutes match this? Is this fire rating necessary?

8.  What research and development is underway or planned in this product
    category?  To what extent are recently developed or introduced sub-
    stitutes such as fiber-reinforced cement sheet and wood products being
    produced and sold in the United States?

9.  Identify any health and environmental effects of the materials used to
    substitute for asbestos in this product category.
                                     192

-------
SUBSTITUTES FOR ASBESTOS-CEMENT PIPE .


1.  Identified uses of asbestos-cement  pipe are pressure pipe (water mains,
    laterals) and non-pressure pipe (sewer mains,drainage and irrigation
    pipe, and electric and telephone conduit).   What other uses of asbestos-
    cement pipe exist?

2.  Only glass fiber is currently employed as a reinforcing fiber in a
    commercial asbestos-cement pipe product.  Have any other fiber replace-
    ments for asbestos in asbestos-cement pipe been identified?  Other than
    ductile iron pipe, concrete pipe, plastic pipe, and vitrified clay pipe,
    are there any products that may be  used to substitute for asbestos-cement
    pipe?

3.  What are the technical performance  characteristics of the substitutes in
    this category?  What implications do characteristics like pipe flexibility
    and burst strength have for the use of substitutes?

4.  What are the lifecycle costs of the substitutes?  We would like information
    on costs of production, transportation, installation, maintenance, and re-
    placement (i.e., product lifetime).

5.  Could existing equipment or processes be used to produce glass reinforced
    cement pipe?  If changes in equipment or processes are necessary, what
    would be the costs of those changes?

6   Would energy requirements be changed substantially by switching to produc-
    tion or use of the nonasbestos material?

7.  What are the existing performance standards or product specifications
    required of asbestos-cement pipe?  Do substitutes meet these standards?
    Would any of these standards be unnecessary if substitute materials were
    used?

8.  What research and development is underway or planned in this product
    category?

9.  Identify any health and environmental effects of the materials used to
    substitute for asbestos in this product category.
                                       193

-------
                    SUMMARY OF THE ROUNDTABLE DISCUSSION
                            ON FRICTION PRODUCTS
PANEL MEMBERS

          Jeatmette Wiltse —  (Moderator) EPA, Office of Pesticides and
          Toxic  Substances

          Al Colli — EPA, Office of Pesticides and Toxic Substances

          Jim Hughes — EPA, Office of Pesticides and Toxic Substances

     Jeannette Wiltse of the Environmental Protection Agency (EPA) described
the EPA's interest in comments on the issues listed in the handout or any
other information the participants in the discussion might want to convey.
She asked about  the role of substitutes in the aftermarket when, for instance,
a friction material has an asbestos substitute.  Mr. Drislane of the Friction
Materials Standards Institute  (FMSI) replied that some replacement brakes for
semi-metallic original equipment brakes are nonasbestos and others contain
asbestos.  He suggested that perhaps after several years, like will be replaced
with like.

     Jeannette Wiltse of EPA asked how brake repair people know what to use
as replacement parts?  Mr. Drislane replied that the field has this informa-
tion but the concern of the brake repair shop people is about product
liability.

     Jim Hughes  of EPA asked if small brake manufacturers could have capital
equipment and financing problems in converting to nonasbestos friction pro-
ducts.  Mr. Drislane of FMSI replied that this will be a real problem for
some of the smaller manufacturers.  Jim Hughes asked if plant closures would
result.  Mr. Drislane replied that he could not predict that, but suggested
that in 5 years most people will be using the same type of material.

     Mr. Ward of General Motors (GM) said the entire brake system is designed
as a unit.  The  engineers who make substitutes indicate that problems could
result if replacements are not made of materials similar to those of the
original equipment.

     Mr. Brunhofer of Bendix said that the friction material is part of an
overall system.  Substitution should be studied carefully or else problems
in safety or wear may develop.  The aftermarket materials have been developed
over a long period of time.  He said that as you phase into a revolutionary
period problems may develop, but that time is a big healer.


                                    194

-------
     Al Colli of EPA said that some firms apparently do  not  have  the techno-
logy to manufacture nonasbestos brakes.   Do major manufacturers of nonasbestos
brakes have provisions for licensing or  do they hold the technology  as
proprietary?

     Mr. Brunhofer of Bendix replied that his company has many license  agree-
ments today, but they are for the international market and they usually
include territorial exclusions.  Bendix  is not aggressively  pursuing licensing
but has not excluded the possibility.  Significant amounts of  company funds
have been expanded to develop new technology.

     Jim Hughes of EPA said that EPA is  concerned about  the  effects  of  possible
regulation of asbestos on small business.

     Mr. Drislane of FMSI commented that semi-metallic brake development began
in 1962 before asbestos was an issue.  It is utilized because  it  meets  market-
place needs.  Mr. Rosenberg of Borg Warner said that they manufacture manual
clutches which use friction materials containing 50 percent  asbestos.  Several
years ago they made a corporate decision that they should develop asbestos
free friction materials.  He said that they did not do this  because  of  environ-
mental concern from asbestos, but because they wanted to protect  our employees
from occupational exposure.  He said that several million dollars have  been
expanded and they are close to their goal.  They may enter license agreements
or manufacture in Brazil.

     Al Colli of EPA asked what tests or design consideration  go  into brakes
manufactured for the marketplace.  Mr. Ward of GM replied that if you used an
asbestos lining instead of the currently-used linings, the  car would still
stop safely.  However, the life expectancy of the braking system would  be
poor.

     Al Colli of EPA asked if more stringent- government  requirements on
original equipment brakes as opposed to brakes for the aftermarket would
result in the manufacture of asbestos replacement for semi-metallics.  Mr.
Ward of GM replied that when dealing with smaller cars,  the size of the
braking system may be a consideration.  Mr. Brunhofer of Bendix commented
that semi-metallics have been designed into the system because of their high
temperature properties.  Organic materials (such as asbestos)  have high wear
rates above 350°;  Semi-metallics can withstand temperatures of 650° to 700°.
Most vehicles in the past operated in the 250° to 400° range.   Temperatures
of the new front brakes on small vehicles may exceed 400°.   Wear is  greater
if you substitute an organic for a semi-metallic material.  The difference
is greatest with a small compact car with a solid rotor.  Also, you will not
pass SAE (Society of Automotive Engineers) or federal fade requirements on
many small vehicles with a solid rotor.  If you substitute an organic  material
for a semi-metallic, you can also develop brake lock on slippery  surfaces.
Mr. Chastine of Abex supported what Mr. Brunhofer of Bendix stated by  saying
that Abex does not compromise quality in the aftermarket.
                                      195

-------
     Mr. Burgess of the Wheeling Brakelock Manufacturing Company said that they
do not have the capacity or know-how of GM or Abex, but that they start where
those companies leave off.  Wheeling Brakelock makes very large brakes for
industrial equipment.  They make brakes that weigh up to 75 pounds, are 5
inches thick and 120 inches in diameter.  Mr. Burgess said that the asbestos
they're using is 40 cents per pound, but the stuff they have to replace it
with is $8.00 per pound.  Also there are problems with molding.

     Jeannette Wiltse asked how big this market was, and asked if substitute
materials had penetrated the market.  Mr. Burgess of the Wheeling Brakelock
Manufacturing Company replied that there had been no market penetration by
manufacturers of substitutes.  He said this is a highly specialized business
with only 5 companies left out of 20 several years ago.

     Jeannette Wiltse asked if substitutes had ever been tried in these
applications.  Mr. Burgess of Wheeling Brakelock Manufacturing Company replied
that his company gives all its money to EPA and OSHA (Occupational Safety and
Health Association) so they have nothing left.  The size of the market is
small compared to the auto market.

     Jim Hughes of EPA asked approximately how much asbestos does your company
use?  Mr. Burgess replied that he did not want to say, but that EPA could
find out from Canadian records.

     Mr. Ward of GM said that many industrial machines have asbestos brakes
that are essential to industry.

     Jeannette Wiltse of EPA asked what are the performance characteristics of
nonasbestos drum brake linings—noise, wet recovery?

     Mr. Brunhofer of Bendix replied that there are four main categories for
design considerations—friction stability, wear, effect on opposing surface
and noise.  There is information in the literature on the materials that can
be used.  Nonasbestos drum brakes have slightly higher friction but approxi-
mately equal wear if engineered properly.  They have acceptable mating surface
wear, but noise is a problem.

     Someone asked why American manufacturers do not make cars with four
wheel disc brakes like foreign car manufacturers.  Mr. Brunhofer replied that
the answer was cost.  Rear brakes have become parking brakes in many
applications.

     Mr. Burgess said that every brake they manufacture has greatly different
design requirements.

     Al Colli of EPA asked how the design criteria for all these applications
is determined.  Is it an art or is there a scientific basis?
                                      196

-------
     Mr. Burgess of the Wheeling Brakelock Manufacturing Company said the
manufacturer has a starting range for coefficient of friction and it is trial
and error after that.  You have to have the right brake block for the job.

     Mr. Moulton of DuPont said that he would like to make a comment on Kevlar®
aramid fibers manufactured by DuPont.  He said that Kevlar® has high tensile
strength, frictional stability, and excellent durability.   It is used in disc
brake pads with wear levels between that of asbestos and semi-metallic mate-
rials.  Kevlar® is being used in experimental drum brake linings and wet fric-
tion papers.  Kevlar® does not score mating surfaces.   It is used in manual
transmission for the Mercedes, Audi, and Porsche.  The fiber is available in
a short pulp form at $3.75/lb.  Only small amounts are required with deep
filler materials so that the cost is between 20 percent and 40 percent greater
than for asbestos with the lifetime cost approaching that of asbestos.

     Mr. Brunhofer of Bendix said that their company went ahead on a crash
basis because of pending OSHA (Occupational Safety and Health Association)
regulations during the last 3 years.  If the development had been over a
longer period of time they might have investigated other materials.

     Jeannette Wiltse of EPA asked if new tooling and equipment is required
for nonasbestos brakes.

     Mr. Brunhofer of Bendix replied that some new equipment is required for
manufacturing disc brakes.  Different materials require different equipment.
For nonasbestos drum brakes, radical changes in processing may be required.

     Jim Hughes of EPA asked how the life cycle costs of nonasbestos brakes
compare with asbestos.

     Mr. Brunhofer of Bendix replied that life cycle costs have not been
taken into account.  He said that semi-metallics have higher life cycle costs
than organics; but the former brakes are smaller and lighter, therefore
result in higher fuel economy.

     Al Colli of EPA said that in 1985 all disc brakes on new cars will be
nonasbestos.  We know that Bendix, Delco, and Abex have the technology.  What
plans to the other companies have to obtain the  technology?

     Mr. Morris of Alfred University said that more basic research  should be
done on substitute fillers to tailor characteristics to meet asbestos
applications.

     Jeannette Wiltse of EPA asked how extensive is the basic  research on
substitute materials.

     Mr. Morris of Alfred University said that in  the  past  several years they
have had three contracts in the friction area.   More work should be done.
                                     197

-------
     Mr. Melner of Jim Walter Research said that he represents a company that
manufactures asbestos replacement material.  They contracted to manufacture
about 16 million pounds of the material because of rumor or fact on regulations
pending on asbestos.  If their substitute material works, they are concerned
about possible effects from it.  He said that they have not received any
guidance from government regulatory agencies.  As a supplier they are about
to commit a quarter of a million dollars for testing.
                                      198

-------
                    SUMMARY OF THE ROUNDTABLE DISCUSSION ON
                 SUBSTITUTES FOR ASBESTOS GASKETS AND PACKINGS


PANEL MEMBERS

     Hugh Spitzer — (Moderator), CPSC

     Pat Harrigan — EPA, Office of Pesticides and Toxic Substances

     Kirk Johnson — EPA, Office of Pesticides and Toxic Substances

     I am Hugh Spitzer, Project Manager of Asbestos Products at CPSC.  We
will proceed from the presentation given by Steven Koehler in the Work
Session on Gaskets and Packings.  You have received an agenda listing ques-
tions around which we want to center our discussion.  I will not go question
by question, but there are topics I do wish to cover.  Also, you may have
questions on materials that Steven Koehler did not cover.  And lastly, and
most importantly, I want to address the health and environmental effects of
the substitutes.

     Hugh Spitzer asked if there are gaskets and packings made from any
other materials other than those mentioned by Steven Koehler in his presen-
tation on gaskets and packings.

     Steven Koehler of Green Tweed Packing Company said that a few sub-
stitute materials that he did not mention in his speech were fiberglass and
ceramic fibers, each bound together with teflon suspensoids-"-Mylar© is the
copy-right name.  Fiberglass, however, is too abrasive and brittle for use as
dynamic pump packing.

     John Arena of Combustion Engineering said that in the first question on
the agenda you state that gaskets are impregnated with a lubricant.  He said his
company manufactures a rope gasket which is 100 percent fiber, with no lu-
bricants or other additives, as it is intentioned for static service.

     Steven Koehler said that is correct.  The first question we address this
afternoon should be on uses of fibers.  Ceramic wicking  is one such  use.
They are for basically static service-door gaskets, etc.
                                      199

-------
      Bill Timmons of Celanese Corporation said that Celanese has just  begun
 to  market a fiber.   Preox (PAN)  is an intermediate material which is avail-
 able commercially.   The main cost factor in the production of carbon fibers
 is  a 50 percent yield loss.   The fibers produced from these intermediates  have
 no  yield loss,  which therefore reduces the initial production cost disadvantage.

      Preox is a precursor to a carbon product.  Bill Timmons addressed a
 question on brittleness saying that these fibers have over 10 percent  elon-
 gation.  Next,  he was asked about the fibers'  behavior in response to  ranges
 of  temperature.  He responded that the conversion to carbon begins around
 300°C,  with a corresponding change in volume.

      Steven Koehler asked Mr. Timmons to define Preox.  Mr. Timmons replied
 that the carbon fibers currently used in packings are based on rayon precur-
 sors, which have only a 20-30 percent yield.  With Preox, Celanese uses the
 fiber itself (trade name Celiox), therefore, loses less in the production
 process.  Polyacrylonitrile precursors (PAN) would result in a 50 percent
 carbon  yield.  These intermediates have a six member ring cross-linked ladder
 structure.

      Hugh Spitzer asked if he had any literature on this material. Mr. Timmons
 replied that he did not have it with him but could get it that day or  the  next
 day.

      Ted Merriman of DuPont de Nemours Company, Textile Fibers Section thanked
 Steven Koehler tor Discussing Kevlar® in packings.  Dr. Merriman discussed
 Kevlar®, saying that it is an aramid fiber which is now used in noncontinuous
 forms in gasket replacements and other asbestos uses.  Kevlar® pulp, produced
 in a process similar to wood pulping, results in a slurry material with short
 fibers  of random length.  This material is amendable to use in wet or  dry
 processes.  Typical beater-add applications are a natural for this material.
 Kevlar® is generally considered to be expensive.  However, the pulp is priced
 at around $3.75 per pound, a less drastic difference from the cost of  asbestos
 fibers.

      Steven Koehler asked if Dr. Merriman knew about Kevlar® in heated water
 under pressure.  He asked if there were any known problems with breakdown  of
 tensile strength at, say, 300°C.

      Ted Merriman said he had not done experiments with 300°C water.
 They have used 212°C water with no breakdown.  Kevlar® begins to breakdown
 at  400°C, through irreversible oxidation.  The products of degradation depend
 on the  process; i.e., conditions of degradation; mostly carbon is produced.   Any
 other products are proprietary information.  When Mr. Koehler asked about  the
 likelihood of glassification, Dr. Merriman replied that Kevlar® does not sub-
 lime.  When asked about possible volatility of Kevlar®, Dr. Merriman  replied
 that there are volatile products of the degradation process.  When asked if the
 pulp process is a shearing process in water, Dr. Merriman replied that the
^process is a standard papermaking technology.  He said that if it works for
 wood products,  it will work for Kevlar®.  He said that he represented  the
 Kevlar® Research Group in Maryland and the Wilmington, Delaware Chestnut Run


                                       200

-------
Site.  When asked about pH, Dr. Merriman replied the Kevlar's  sensitivity to pH
may limit its use as a substitute for asbestos-cement pipe.  He said they
have not determined pH ranges yet.

     Steven Koehler said that they had identified Kevlar® pH range as between
3 and 11.  However, compression of the material may increase friction, heat,
and therefore, wear on the material.   This in turn would increase any degradation
that may be caused by the presence of acid.

     Ted Merriman said that it depends on whether you are in a high shear
environment or not.  Steven Koehler agreed, saying that pH ranges can depend
on the pressure involved.

     John Zeltz of the Victor Division of Dana Corporation said that the
volume of this segment of the industry is in service gaskets.   He disagreed
with the assumption that there are technical substitutes for gaskets in areas
related to engine products.  He said that one cannot predict that a new prod-
uct will be usable in those uses especially in cylinder heads or service
manifolds.

     Steven Koehler said that the substitutes would probably function, but
the question is whether the new product is cost-effective.  There are avail-
able substitutes that can be used.

     John Zeitz replied that substitute gaskets would have to be designed for
each specific application and mentioned possible problems with load difference.

     Bill Olden of Union Carbide said that they have graphite materials used
for head gaskets that are flexible on any engine.

     John Zeitz expressed doubts about, the service of these graphite materials
on new designs.

     Mickey Hosmer of Jim Walter Resources said that they produce fibers at a
cost of 25 cents per pound, much cheaper than longer fibers.  John Zeitz asked
about the length of these fibers.  Mr. Hosmer replied that they have a 40-60
percent aspect ratio.

     Gordon Yuellig of Proctor and Gamble asked how many substitutes meet FDA
regulations for contact with food, drugs, cosmetics, and medical devices.

     Steven Koehler replied, "One: Teflon®".  Mr. Kelly said they have been
trying for years to find components of packings that will meet with  FDA
regulations.

     Al Diangelos said that Gore-tex, a PTFE fiber has also been  approved;
however, this is also a Teflon® derivative.

     Mr. Yuellig asked what we would do when we need a material that has a
temperature range above the 400°C range of Teflon*.  Steven Koehler replied
that possibly metal gaskets could be used.  Mr.Yuellig  said  that that is a
very poor substitute.  (Later, he added that there  are  only temporary solutions.

                                      201

-------
There is no satisfactory metal packing.)

     John Halberta of Carborundum said that they produce Grafoil  , ajElexible
graphite product.  They said they are close to FDA approvaT~for itsT use re-
lative to food additives.  They have one more hurdle  (rat studies, etc.), which
they hope to clear in one more year.  Aramid products, too, might be approved if
they are pushed.

     Mr. Yuellig said that they had been trying to get rid of asbestos for
years but the FDA has not revoked its use.  Mr. Diangelos said that Dr. Kreska
of the FDA is the man they have been working with.

     Steven Koehler asked if we wanted to get rid of  asbestos, but are not doing
so.

     Hugh Spitzer replied that there is sometimes a fear among the regulatory
agencies that in banning one product, you unleash a worse product on the market.

     Steven Koehler asked if asbestos has to pass standards such as those the
substitute must pass.

     Hugh Spitzer asked, other than technical and FDA specifications, what
specific needs and performance standards do you have  to meet?

     John Zeitz replied that for temperature they need a standardized ignition
loss test which ASTM  (The American Society for Testing and Materials) can
provide.  They will be buying temperature resistance  with this substitute.
It functions satisfactorily in the 600-800  (possibly  to 1000°C) range.

     Thomas Jackson of Johns-Manville Corporation said that there is an
existing standard now that goes up to 1500°C, which is now being revised;
whether it is adequate or not is unclear.

     Al Gordon of Federal-Mogul Corporation said, regarding performance
standards and material specifications, ASTM is an agency operating under a
voluntary set-up.  ASTM promulgates both material specifications and test
methods.  F-8 is the Committee on Gaskets.  Most standards are methods of
testing, also spelling out physical and certain functional properties.  In
addition, a classification system is used to determine the appropriate
specification.  Virtually all deal with non-metallic  and non-rubber materials.
(D-ll is the Committee for Rubber Materials.)

     ASTM was started at the request of the government, to develop standard-
ization.  It is concerned with environmental issues.  There may be an
opportunity for coordination:  Any asbestos replacement materials would fit
into the classification system.  If not, provisions have been made to allow
for incorporation of new materials.  SAE (Society of  Automotive Engineers)
engineers use ASTM's standards rather than duplicate  their work.  The military
also has a system set up to parallel ASTM's classification.
                                      202

-------
     Ted Merriman added that there is a military specification for graphite:
24503.

     Steven Koehler said that there are military specifications for most
graded packing materials.  Teflon filament,  for example,  is MIL-P-24377.
One problem here is that when the military asks for bids,  they specify
materials, and will not accept substitutes.   Someone said  that there is now
a concerted effort in the Navy to get rid of asbestos.

     John Zeitz said that the military is very slow here.   In some cases,
they ask for asbestos.

     Hugh Spitzer asked if those specifications spelled-out asbestos materials
only.

     Steven Koehler said that performance characteristics  are specified as
well.  Some military specifications require  asbestos; and  these will probably
be the last to change.  They purchase a lot  of asbestos.

     Mr. Yuellig said that substitution for  asbestos means diversification.
Asbestos was so versatile.  Using flax again is a regression; it is corrosive,
and does not function well at extreme temperatures.

     Steven Koehler said that for pumping applications,  long run, cost
effective, over-engineered, substitutes exist.

     John Halberta said that they have a substitute and they would hate to
have to compete with flax.

     John Zeitz said that they may be able to get more materials into the
market places.  Finding direct substitutes is a minimal goal, although it
will not look so for the next five years.  It will look like a snowstorm.

     Steven Koehler said that when asbestos was discovered to have so much
versatility in its gasket and packing applications, some reliable old stand-
bys were overshadowed.  He estimated that some 40-60 percent of asbestos
uses were unnecessary and were used simply because they were convenient.

     Ted Merriman said that is the very point.  Without much technical
background, the average mechanic knows about asbestos and knows  it will work.
I agree that if you over-engineer with graphite, everything will work out.

     Mr. Yuellig said if you are a small businessman without extensive
technology, asbestos is so versatile that it works for just  about  any need you
have.  It will take a lot of good material  to  replace it, with the exception
of food products.

     Louis Blecker of GAF Corporation asked what the health  risk of  asbestos
was.  He asked how much exposure there was  and does  it warrant all this cost.
Hugh Spitzer replied that this workshop is  concerned with substitutes for
asbestos.  Louis Blecker asked if we needed asbestos substitutes.   Hugh Spitzer


                                      203

-------
replied that we are gathering information to find this out.  Louis Blecker
said then why not use scientists, and competent people to study the problems
in a noncompetitive, nonadvocacy setting.  Hugh Spitzer thanked Mr. Blecker
for his comments.

     Herb Posner of NIEHS (the National Institute for Environmental Health
and Safety) said that they are looking at a number of real world situations
(brake linings, hair dryers, and so on) where there is an opportunity for
asbestos exposure.  He said there is good evidence of the hazards of asbestos.
He said that as he saw it, the purpose of this conference is to identify where
exposure occurs and substitute asbestos with less hazardous substitutes.  He
expressed concern that the health aspects of asbestos are always last on the
agenda, but acknowledged that perhaps that was alright because there was a
day and a half of health sessions scheduled.

     Gordon Yuellig said he had a question for Mr. Posner.  He said that
everything he had read, including Dr. Selikofffs study, stated that everyone
who has been exposed to asbestos was affected long ago.  He asked how the
health hazards of asbestos exposure from hair dryers, et al, could be corre-
lated with exposures from the asbestos industry.

     Herb Posner asked how long have hair dryers been used.  Ted Merriman
asked how much asbestos gets out from these hair dryers.  He said that GE
(General Electric) went along with the hair dryer recall because of adverse
publicity but later studies showed few, if any, fibers get released.

     Herb Posner said that asbestos-cement sheeting, when misused in schools,
creates an exposure problem.

     Derek Kuhn of the Richard Klinger Corporation said that he knew that
only substitutes are to be discussed, but asked if we could distinguish
between friable and encapsulated asbestos here.

     Hugh Spitzer replied that he would prefer to limit discussion to sub-
stitutes for asbestos.

     Derek Kuhn asked if there was any overlap when you consider encapsulated
asbestos hazards as compared to the friable non-asbestos fibers,

     Hugh Spitzer said that it is not appropriate to discuss asbestos issues
now.  He said the purpose here is to gather information on health effects,
etc. of other materials.

     Herb Posner asked about uses of asbestos in gaskets and sealants.  What
about workers who are exposed during servicing and installation?  Someone
replied that that is not for this forum and the group should stick to dis-
cussing substitutes.

     Hugh Spitzer said that perhaps they should go to the health effects
studies.  He asked what results FDA (the Food and Drug Administration) had
been getting from their studies.


                                     204

-------
     John Halberta referred to Grafoil  gaskets in his reply.   He said that
his company (Carborundum) had to do earcinogenieity studies,  and that their
results showed no effects on rats.  For PMAs (polyaromatic hydrocarbons),
they have to demonstrate a concentration of 2 ppb or less. He said that the
sensitivity of the test had been the major difficulty in analyzing Grafoil
for the presence of PMAs.  He said they could not find PMAs in flexible
graphite, so it was treated and then analyzed for PMAs.   (No  animal tests
were done.)

     Hugh Spitzer asked if asbestos has been shown by the FDA to meet the  2
ppb hurdle.  He also asked how this standard was set.

     A participant replied that FDA set the 2 ppb standard.

     Hugh Spitzer said that one problem with comparing asbestos to an organic
substance is asbestos is for all practical purposes not metabolized.   Asbestos
can stay in the tissue, while other substances can be metabolized and
excreted.

     Malcolm Fenton of Marrietta Resources International, Ltd. said they
manufacture Suzorite mica.  He said when they tested a hypothetical process
and product for health effects, the data would necessarily be outdated within
five years time.  By then, the use and exposure would be different.  He asked
what the Federal agencies expected from health studies on substitutes.

     Hugh Spitzer said that answer would be "safe material".   Let me elab-
orate—regulatory agencies depend on scientific reports in assessing any
chemical or product with respect to health effects.  Animal bioassays,
epidemiological studies and in vitro testing are all of value.

     Malcolm Fenton commented that Bendix has spent millions  of dollars on
health research; a development which is good both for the American people and
obviously for their company.  He said that the job of the government was to
make sure that all brakes in the U.S. work.  He asked if there was (any
possibility of) a bill in Congress to give companies like Bendix a tax break
on such work.  He also asked about possible tax breaks for small companies.

     Hugh Spitzer commented that there is a National Toxicology Program (NTP)
which recommends material to be tested.  One criteria for material to be
reviewed by the NTP is large production/use volume.  This  is  an established
program available out of NIH (the National Institute of  Health) coordinated
with CPSC, EPA, and FDA.  The government is concerned with industry  concerns.

     Malcolm Fenton said he assumed, then, that  if a material is widely used,
it can be evaluated by government methods.  He also asked about material  not
yet widely used (which you would like to have widely used).

     Hugh Spitzer replied that he should talk to the agencies to  try to get
into a testing program.  Herb Posner said  that NTP  is  already trying to get
thousands of chemicals into at least short term  tests  as a start.
                                      205

-------
     Hugh Spitzer said that his advice was to keep after the agencies.  He
suggested that companies should try to get chemicals into the testing program.
He continued by asking for information on the kinds of tests of materials
which are underway or planned (by industry).

     A participant suggested to Hugh Spitzer that one of the other consider-
ations is energy requirements from producing and using these substitutes.

     John Halberta commented that the silence indicated a general lack of
knowledge on testing.  He indicated that participants (from industry) were
being asked whether they had done work on a product that might or may not be
acceptable by the government.  He said that no one has any experience in
getting products approved.  (Also, the economies of scale for asbestos re-
placement are not yet well understood.  However, asbestos replacement
presents us with a marvelous opportunity, however elusive it may now seem.)
He said that (the government) had many definitive questions but that they could
only supply vague answers.

     Hugh Spitzer asked for best guesses as to the needs of companies.

     John Zeitz replied that they might require a multiplicity of systems,
but they would not have to start from scratch.  Existing equipment will not be
thrown out as boat anchors.

     A participant commented that the manufacturers of substitute fibers
should be asked that question, not the users.  Someone commented that
capitalization for substitutes right now is not great.

     John Halberta said that the question is whether you will have significant
enough incentives (e.g. tax incentives).  Without incentives, new technology
will not be developed.

     Louis Blecker said that they have just built a glass plant; there is a
tremendous need for capital.

     Ted Merriman said that most of the emphasis this afternoon has been on
fibrous substitutes.  Nonfibrous replacements will be important, too.

     John Halberta said that their product, Grafoil , is nonfibrous.
Production may require new capital.

     Hugh Spitzer asked if there were any further comments on nonfibrous
substitutes.

     Frank Fry of Hollingsworth and Vose replied that the pressure will work
backwards from the user to the fiber supplier, each trying to conserve
capital.  The incentive for change will come from the end users.

     Hugh Spitzer said thank you very much for coming this afternoon.
                                     206

-------
         SUMMARY OF THE ROUNDTABLE DISCUSSION  ON  SUBSTITUTES FOR ASBESTOS
                         IN PLASTICS AND FLOORINGS
PANEL MEMBERS

     Gale Wyer — (Moderator),  CPSC
     Terry Karels — CPSC

     Will Stelle — EPA, Office of Pesticides and  Toxic  Substances

     The meeting was attended by 20 to 30 people.   The two hour  session was
divided into two portions:  the first on plastics  and the second on flooring.

PLASTICS

     The success of the search  for substitutes for asbestos  fiber depends
upon the function of the asbestos in each particular product and product
category.  Asbestos fibers provide good tensile strength and possess good
thermal resistance.  In addition, they also serve  as a cheap filler for
plastic mixtures and make them  easier to mold and  to work.   Many fillers are
available that are cheaper than asbestos but do not possess  the  same
strength or heat resistance.

     If the thermal insulation  or tensile properties of  asbestos are necessary,
replacement may require using several materials together,  such as a mixture
of mica and an organic material.  If these special properties are not
necessary, organic fillers may  be used, which are  often  cheaper  than asbestos.

     It was also noted that man-made fibers are generally more expensive
to produce than refined asbestos.  Substitutes, especially man-made materials
are not as permeable as asbestos, to chemical constituents  such  as dyes.
Different, possibly more expensive means of production,  could be necessary
when man-made fibers are used.

     Manufacturers are often looking for products with greater reinforcing
and insulating properties than asbestos; this is due to increased demand for
high-performance materials by industrial users.

     One view was that unless the use of asbestos is banned that it will
continue to be used since the product is effective and cheap.

     Other views were that consumer pressure would eventually drive manu-
facturers away from asbestos and that this pressure was preferable  to  an
outright ban because the latter would cause serious economic problems  for


                                      207

-------
 the  industry.  An example  of  this  pressure  is the increase in lawsuits.
 Aother  example is the  shift away from asbestos use in hair dryers suggested
 by CPSC.

      One  participant questioned the health  hazards caused by using asbestos
 in plastics  and  also stated that,  regardless of the actual risk, the market
 was  demanding plastic  products that did not contain asbestos fibers.  Con-
 sequently, he stated,  the  industry desired  to move to substitutes where such
 substitutes  were available.

      Eula Bingham of OSHA  was represented as saying that there is a substitute
 for  every application  of asbestos.  Attendees argued that defense and
 national  security reasons  could be used as  reasons for continued use.

      Participants said that an imposition of a ban would harm the industry.
 Larger  firms may gear  up for  substitutes; smaller firms may not be able to
 gear up.  Smaller firms cannot afford to tie up capital for research and
 development  and  may be driven out  of business.

      A  suggestion was  made that CPSC and EPA contact plastics and other
 professional organizations and associations for further information.  Two
 participants cited as  a useful compilation  of substitute information a recently
 published book,  Handbook on Fillers and Reinforcements.

 FLOORING

      Asbestos is used  as reinforcement in vinyl asbestos (V/A) tile and as
 a backing in vinyl sheet.  The lengths of fibers used in each application
 are  different:   the backing uses longer fibers, while V/A tiles use shorter
 fibers.

      Nothing more was  discussed; members said that the industry is very
 secretive and will not share  technology.  There are tremendous costs involved
 in research  and  development for substitutes, and the firms will not share
 expenses.  Further, the firm  that  finds an  acceptable substitute "stands to
make  a lot of money" and may  end up controlling the market.

      Because no  one was willing to speak about flooring, the attendees were
encouraged to submit written  remarks.
                                      208

-------
                  SUMMARY OF THE ROUNDTABLE DISCUSSION ON PAPER
                              AND ROOFING PRODUCTS
PANEL MEMBERS

          Suzanne Rudzinski — (Moderator) EPA,  Office of Pesticides
          and Toxic Substances

          David Bailie — Koppers Company

          Nancy Roy — GCA Corporation

          Christine Spadafor — EPA, Office of Pesticides and Toxic
          Substances

          June Thompson - EPA, Office of Pesticides and Toxic Substances

     In response to a question by Ms. Rudzinski  asking if there were any
uses of asbestos paper products for which there  are no known substitutes,
Mr. Huseby, General Electric (GE) described an asbestos paper tape used in
GE transformers for which GE is seeking a non-asbestos substitute tape.
Ms. Carol Mansfield, Carborundum, then proceeded to describe her company's
line of ceramic fiber papers, their characteristics and cost range, claiming
Carborundum's paper line is economically competitive with asbestos paper.

     Ms. Rudzinski inquired if any representatives of aramid or ceramic
paper manufacturers were present.  Carol Mansfield (from Carborundum) indicated
that she and a representative of Babcock and Wilcox were present.

     Mr. H.B. Kinsley added that James River Paper Company also makes a line
of ceramic papers.

     Ms. Rudzinski next directed questioning to  what in the way of performance
characteristics is lacking in substitutes.

     Mr. Beto, GAF, stated that (for flooring) his company knows of no direct
asbestos substitute which is an economical, high performance, fire resistant,
noncombustible material.  Mr. Beto went on to say that there is no single
substance (listed on the summary handout of substitutes) that does not have
some deficiency when compared to asbestos.  Also, when one looks at  the
economics, there is no good replacement.
                                      209

-------
      Mr. Beto, in response to a question about GAF's ability to find suitable
 substitutes, stated that his firm is spending hundreds of thousands of dollars
 trying to find substitutes.

      Ms. Rudzinski asked about the cost differential between fiberglass-
 containing and asbestos-containing products.  Mr. Waldman of International
 Paper Company said that the question cannot be answered directly because of
 price differences between grades of asbestos.

      Mr. Kinsley of the James River Paper Company stated that Hercules has
 been working on their lexar fibers and that they presented a paper on the
 process within the past year.

      Ms. Rudzinski asked if there are any applications (for paper products as
 well as for roofing products/coatings) for which there are no acceptable
 substitutes.

      George Odean of DuPont responded that in the line of specialty papers,
 there is no direct substitute for asbestos membranes in certain electrolytic
 cells.  DuPont manufactures a line of asbestos-free membranes, Nafion, for
 some elctrolytic diaphragms but it is not a direct substitute for the cells
 that now use the asbestos membrane.   In order to use the Nafion membrane,
 the existing cells have to be replaced.

      A representative of the Chloralkali Institute stated that the substitute
 represents companies which manufacture Coroden® and that 75 percent of the
 use is for diaphragm cells.  He stated that asbestos is used with the dia-
 phragm material and that there are no substitute membrane cells.

      An estimate of 2 billion dollars was given for the conversion from
 asbestos to  substitute material in the chloralkali industry.

      In response to a question about what type of properties would be required
 for a suitable  substitute for the asbestos membrane cell,  the Chloralkali
 Institute representative stated that he did not want to address that  at the
 present  time.

      Mr.  Edmond Berrigan of DuPont Industrial Fibers Division stated  that  he
 wanted  to describe  fibrous  asbestos  replacements which DuPont is  developing
 called Kevlar® and Nomex®  They are  continuous filament aramid fibers.   The
 fiber is  used as  reinforcing  material for a number of applications, especially
 for paper uses.   It  is  economically  competitive at a cost  of  $3.75 per pound
 for the pulp.   Like  asbestos,  fibrous material has desirable  characteristics
 such  as high tensile strength.   The  fibrous pulp material  has releasable
 fibrils with aspect  ratios  in the  respirable size range.   Mr.  Berrigan went on
 to say that this  fibrous material  is  well suited for applications  like paper
because it is made by paper-making processes.   However,  the material  can also
be used for other products  such  as beater-add gaskets or friction  paper.   Be-
 cause the cost  is high by asbestos standards,  Kevlar® pulp is obviously not a
                                      210

-------
direct substitute for all asbestos in paper products;  however,  it can replace
a small quantity of asbestos.  Also, there are some applications, such as for
gaskets and friction paper, where it is economically feasible to use higher
priced fiber like the Kevlar® pulp.

     In response to further questioning, Mr.  Berrigan indicated that there are
definitely fibrils of inhalable size that can be released from the Kevlar® pulp,
but that it is very difficult to get the fibrils out of the material.  The
exact number of fibrils that are releasable is not known, but it is a very
small percentage of the total.   However, DuPont has addressed the problem of
the inhalation toxicity of aramid fibers.  A paper presenting preliminary
results of an inhalation study will be given in the Health Effects Session.
To date, there is no evidence that DuPont should not continue to develop
production of these aramid fibrous materials.

     Vance McCarthy (a reporter with a Mineral publication) brought up the
question about what guarantee is there that people who invest in research for
asbestos substitutes would not have to replace the substitutes later on after
they are tested.

     Members of the panel asked that questions associated with health effects
of substitutes be deferred to the Health Effects Sessions.

     Mr. Stimola asked that the group address a second question; what fibrous
product substitutes exist in the protective coating product field?  In the
category of protective coatings, Mr. Stimola indicated that his firm knows of
no effective substitutes for asbestos even if they disregard economic con-
siderations.  Although their firm is familiar with many products offered as
asbestos substitutes, in their opinion the substitutes do not work as well
as asbestos.

     Jim Palmer, MiniFibers, stated that his company has a high density
polyethylene fibrous coating formulation that he has been working with for
about three years.

     There are about 16 formulations for protective coatings, rib coatings,
etc.  The fiber itself is called the "130380" and is economically competitive
with asbestos.

     In response to a question about the material's degradation by mildew,
etc., Mr. Palmer responded that he was not too familiar with that aspect of
the product, but that he would give the questionner some literature.

     Another participant (unidentified) stated that he would be  speaking for
the roofing industry  concerning substitutes for asbestos fiber.  He
indicated that his firm has worked with MiniFiber's product and  does not find
it to be a viable substitute for asbestos regardless of cost.

     In response to Ms. Rudzinski's question as to what reason his  firm finds
that the MiniFiber product is not an acceptable substitute,  the  unidentified
participant stated, for one thing, they could not keep it from settling.  Also


                                     211

-------
 they had found it to be a fiber that burns and does not provide body to  the
 coating material.

      A question was addressed to the chair about what EPA and the Office of
 Toxic Substances thinks of synthetic organic fibers.  The question about fiber
 size was deferred to the Health Effects sessions.  Participants were asked to
 submit any weathering data that might be available.

      The same participant raised doubts about synthetic fibrous coating
 materials stating that the use of toxic fungicides  compounds  the (possible
 health) problem.  The staff invited the participant to submit any data he
 might have on fungicides'"wear, etc.

      Philip Battoli, GAP, stated that his company has been making roof coatings
 for 90 years.  Mr.  Battoli stated that unfortunately there are now no
 alternatives for asbestos for reasons already discussed.

      Mr. Battoli stated he was not convinced that polyethylene or polypropylene
 fiber is suitable for an outdoor environment.  For  example, in such
 applications as flashing cement, a vital part of the roofing structure,  these
 organic fibers might not be able to withstand ultraviolet light, temperature
 and other forces of nature as well as asbestos fiber could.  Mr. Battoli went
 on to say that shelf stability of alternates is not as good as that of
 asbestos.  There are also problems of premature failure and lack of proper
 reinforcement.  So, if there is an alternate, GAF has not yet found it.

      Also,  GAF has  not found suitable alternates for certain types of gaskets.
 Ceramic fibers may  be useful in certain types of gaskets, but not for all.
 Head gaskets, for example,  have different performance requirements than
 exhaust gaskets.  Alternates for asbestos are being tested, but there is no
 assurance of long term performance.   If a firm converts a tractor or pit
 asbestos gasket to  an alternative asbestos substitute gasket, long term  per-
 formance data are needed.

      Next was a discussion  between Dave Bailie,  Koppers,  Inc.,  and another
 participant  about the use of one-ply asbestos-free  membrane material for
 repair  or replacement of existing roofing coating.

      Ms.  Rudzinski  next  asked if there were representatives of  other paper
 products  present  — pipe wrap,  millboard,  etc.,  who would like  to address some
 of  their  substitutes and problems.

      Ms.  Mansfield  of Carborundum stated that her firm has an array of mill-
boards, some  of which are made  with  inorganic fibers and  some of which are
made  with organic fibers.   In response to  the question if Carborundum's
millboard products will  substitute for all asbestos millboard applications,
Ms. Mansfield  indicated  "no", that she did not think anyone had a product
that will substitute in  all  cases.

      It is very difficult to  compare prices of substitute materials with
asbestos products, stated Ms. Mansfield.   For paper,  there are  several grades,
as well as low and high  temperature  paper  lines.  As for  millboard,  there

                                      212

-------
should be no equipment conversion costs, since Carborundum carries the same
sizes as the asbestos board now available.

     Ms. Rudzinski asked if there were paper products other than for certain
gaskets and the flooring already discussed for which there are no known
substitutes.

     Mr. Kinsley of the James River Paper Company stated that in the ten years
since the company has been incorporated it has not made any asbestos-based
products and has been looking for opportunities for non-asbestos products.
However, there are areas where there do not appear to be viable or economical
substitutes.  Beverage filtration is certainly one of those areas.

     A representative of Munson Products stated there are also roof coatings
substitutes which will require equipment changes and very substantial capital
expenditures.

     Ms. Rudzinski next asked about substitute material durability.

     In response, a participant indicated that where organic fibers are used
as substitutes, they degrade whereas asbestos does not.  So there is no compar-
ability as far as durability with these types of substitutes.  With synthetic
coating materials, one has to use a germicide or fungicide to keep rotting
from taking place.  There is not yet enough experience with use of substitute
materials to be able to determine how comparable they are with asbestos-based
coatings.

     The James River Paper Company representative H.B. Kinsley described
some performance problems with a specialty paper their firm is trying to
develop.  With substitutes such as inorganic fibers, there can be problems
with the crush test and with creep resistance.  Also, even if the higher-
melting temperature organic fibers do not creep, they probably crush.  There
is a need for resiliency and high temperature resistance.

     Further discussion of the performance problems of substitutes followed.

     One participant said that roofing systems being installed today are
based on European technology.  But durability of roofing systems  in Europe
really cannot be used for comparison of durability of roofing in  the United
States.  Asbestos roofing systems have proven durability.  Non-asbestos
systems have not been out there under all services, conditions, and applications
long enough for durability evaluations.  Also, accelerated exposure/durability
testing cannot be directly interpreted.  It is like an engine running at  idle
speed.  One cannot say, based on that, what the engine's performance will be
at high speed.

     Glenn Simpson of CPSC inquired about earlier references made to the  fire
retardancy aspects of asbestos in roofing mastic.  Mr.  Simpson  stated  that
references had been made earlier implying that a roofing mastic substitute
                                     213

-------
 (for asbestos)  would not be suitable because it was flammable.   But, Mr.
 Simpson's question was whether the entire mastic mixture was  flammable,
 whether or not  it contained asbestos.

      A participant replied that claims of fire retardance of  asbestos  in
 roofing coatings were not made, rather, the comments relative to roofing
 coatings were made criticizing their organic fibers which degrade on weathering,
 and their tendency to mildew,  which degrades the whole product.

      Asbestos fiber in an organic vehicle in the coating does degrade.  The
 speaker stated  that his firm's organic fibers placed in that  same organic
 vehicle no longer contribute to the weatherability of the coating.  In fact,
 if the coating  and fiber is mildew resistant, it detracts from the weather-
 ability of the  coating.

      Another participant stated that the use of asbestos in asphalt does pro-
 vide a great measure of fire resistance.  A discussion of the characteristics
 of asbestos-based asphalt follows in which the speaker reiterated that
 asbestos-filled asphalt coatings are weather and fire resistant.

      Ray Lawson of Southwest Petrochemical Division, Whites Chemical Company
 stated there is a difference between resistance and retardance.   Lawson
 recited the military specifications for automotive undercoating  on vehicle
 undercoating.   For an asbestos-containing asphalt coating placed in a  flame,
 it has to extinguish itself within a specified period of time (20 seconds
 or so) after the flame has been removed.  With an asbestos-containing  coating,
 the flame will  estinguish itself.   With synthetic or organic  fibers, the flame
 will continue burning.   Mr. Lawson said that is resistance, not  retardance
 and there is a  difference.

      Ms.  Spadafor asked questions about tests for substitutes — were  there
 observed differences in energy requirements for processing substitutes
 versus asbestos products?   Ms.  Rudzinski added a question about  whether
 observed differences in energy requirements would be a controlling factor in
 a  decision to go with either one or the other.

      Sam Elwood of H.B.  Filler stated that for most of the substitutes his
 firm has  looked at,  it  takes a lot more energy to try to get  products  of
 uniform consistency.  When  one is  running a 125 hp motor 20 to 30 minutes
 longer (even up to 1-1/2 hours longer)  to get a uniform mixture, considerably
more  energy  is  being used  than when asbestos is being used.   On  energy con-
 sumption,  this  is almost economically unfeasible.

     A few other comments were made concerning the differences in energy
 requirement  between  substitutes and asbestos-based products.

     Since there was  no  response to Ms.  Rudzinski's question  if  there  were
any other  points or  questions  to discuss,  the meeting adjourned.
                                      214

-------
                    SUMMARY OF THE ROUNDTABLE DISCUSSION ON
                        SUBSTITUTES FOR ASBESTOS TEXTILES
PANEL MEMBERS

     Alan Carpien — (Moderator), EPA, Office of General Counsel
     Bob Liss — EPA, Office of Pesticides and Toxic Substances

     Sam Manfer — Carborundum Company

     Dave Mayer — EPA, Office of Pesticides and Toxic Substances

     Alan Carpien suggested that the group center its discussion on the tech-
nical performance of substitutes, and their lifecycle costs.   He also
suggested that Sam Manfer of the Carborundum Company lead the discussion.
Mr. Manfer invited the group to bring up information on a variety of substitute
areas, since his expertise involved ceramic fibers.

     Rick Hettich of Amatex pointed out the distinction between fire re-
sistent and flame resistent textiles.  Fire resistent means that the textile
will burn when a flame is applied, but will self-extinguish when the flame is
removed.  Manfer pointed out that there are different forms of ceramic
materials.  Some are flame resistent, while others are fire resistent.  He
said that they will remain inert in either case.

     Phil Wagner of DuPont added that while Aramids are self-extinguishing,
flammability may be relatively unimportant.  Sometimes whether or not a
textile is a good thermal barrier is the only important criteria.

     Mr. Kennedy of Raybestos stated that chemical resistance was important
in the manufacture of chlorine.  He said that many different fiber types had
been tried, but that no appropriate substitute had been found.  Mr. Manfer
added that other chemicals needed to be tested.

     Sam Manfer wanted to get back to the question of fire resistance.  He
asked the group whether the leached silica fibers were effective above 1000°F.
Al Weiner of the Navy Department said that the terms self-extinguishing and
non-burning were not meaningful.  He stated that some sort of standard test
was needed.  Manfer asked whether these specifications were  indicative of
the applications.  Weiner stated that the CG test has been used to  try to
indicate this, since no weight loss is the ultimate test of  fire resistance.

     Joe Sonatol of Pittsburg Corning suggested that the group center on
specific product applications.  By generalizing, many cases  in which fire
resistance is utmeeded would be discussed.  It was decided that the list of
applications in question 1 of the agenda should be looked at.

                                     215

-------
     The  first  item was welding  curtains.  Bal Dixit of Newtex added that the
 type of asbestos  fabric must be  specified.  Commercial asbestos with 30 percent
 rayon may burn  under  certain conditions.

     Bob  Liss asked whether there were  specifications for welding curtains.  Mr.
 Manfer replied  that welding blankets have  specifications, but that they may
 be made from a  variety of materials including PVC, rubber, etc.  Some of
 these materials have  been known  to off-gas and produce cyanide.  Lyle Cohen
 of Magid  Glove  Company stated  that specifications are up to the manufacturer.
 Alan Carpien asked whether  there were reasons for using one material over
 another.  Mr. Manfer  responded that curtains were an open area, in that user
 preference  is important.  Welding blankets must withstand molten metal
 puddling.  Asbestos has been the only material thus far to pass the military
 specifications.   Mr.  Weiner disagreed,  and stated that high temperature silica
 products  are actually better than asbestos, have a higher temperature
 capability  and, depending on abuse, are as durable as asbestos.

     The  next product line  discussed was welding blankets.  Mr. Manfer stated
 that leached silica is effective, and asked whether any other materials were
 known to  be effective. Mr. Dixit  added that  there are many non-welding appli-
 cations for blankets  such as covering machinery.  Artie Bower of Gentex
 stated that Preox, Celiox Fiber  is effective against molten metal splash.
 The cost  of this  material is $18-20/yard.  It is generally effective in
 uses where  there  are  short  exposures to high temperatures, but not in long
 term, high  temperature exposures.

     Don  Johnson  of 3M noted that Nextel (a 3M product) when used as a hybrid
 has not passed  the military tests.  It  was suggested that the group focus
 on a discussion of the cost-effectiveness  and end-use specific considerations
 of various  fibers.  Alan Carpien then discussed the requirements necessary
 for a finding on  "unreasonable risk" which EPA must support for each regula-
 tion of a toxic substance.

     Bob  Cordick  of Araco stated that fiberglass is acceptable in textile
 applications where temperatures  are 1000°F, up to 1800°F.  It begins to
 weaken at temperatures of 700°F, but has been used for applications in which
 asbestos  has not  been moved.   Silica cloth is also available for uses in
 temperature ranges of 2000-2300°F.  The cost is dependent directly upon
 application.  In  some applications, it  lasts six times as long as asbestos,
 yet costs only  twice  as much as  asbestos.  There may be additional economies
 involved  through  energy savings.  In steel mills, high temperature textile
 applications have cut energy costs drastically.  Al Weiner pointed out that
 several other parameters reduce  the temperatures that textiles can meet.
 Steam, vibration  and,  refractory temperatures, all effect the durability of
 textiles.

     Phil Wagner  of DuPont  stated that  Nomex, Kevlar, and Teflon were all
asbestos  replacements.  Their  costs range  from $5-$32 per pound versus
approximately $.25 per pound for asbestos.  These materials may be spun of
conventional equipment.  When  Dupont markets these products, they use a
system called the value-use system.  This basically involved defining the


                                     216

-------
exact use for a customer's product.   Producing expensive substitutes can be cost
effective if they are produced quickly, and in bulk.   Also,  if the materials are
light weight (a small amount goes a long way), abrasion resistant, and have
increased longevity over asbestos, they can be sold much easier.   Also, these
materials are rarely used alone but generally as hybrids.  Kevlar and Nomex
are aramids (nylons), they are high temperature resistant, flame  resistant,
and have no known melting points.  They will off-gas  at 800°F, depending on
time and atmosphere.

     Bal Dixit said that their main product, Zetex, is a fiberglass textile.
A representative from Celanese, Bill Timmons, stated  that they produce
"Preox".  This is a thermally stabilized polyacrylonitrile.   It carbonizes
at high temperatures, is not electrically conductive, and has good water
absorption properties.  Additionally it is quite flexible, but emits cyanide
gas at 800°F.  It will not support combustion in air.  Alan  Carpien asked for
submission of additional information on this product.

     Sam Manfer stated that while asbestos is replaceable,  technical material
on its substitutes provides little information on the application of sub-
stitutes.  Alan Carpien responded that the Agency would like to get the best
data possible for decision making.  He called for submission of all substitute
data which could aid the Agency in this endeavor.

     Lyle Cohen of Magid Glove Company criticized all gloves.  He stated that
asbestos gloves are used only where they are necessary.  They are big and
clumsy.  Replacements for asbestos gloves are not good either.  Kevlar
failed, and Zetex is too expensive.  Al Weiner stated that gloves using a
Kevlar and leather combination have been used successfully.   Bill Myers of
Amatex cited a study by Nottick Laboratories on safety clothing which showed
that Kevlar did not hold up in some cases.  Mike Wright of the United Steel
Workers Union stated that steel workers were satisfied with the replacement
gloves.  He noted that in many cases a specific process should be examined.
Often workers could be less involved in high temperature processing.  Sam
Manfer questioned the use of other fibers in gloves.   Bal Dixit said that
other fibers could be used if time was allotted to develop substitute products.
Alan Carpien asked how long this development process would take.  Sam Manfer
replied that time was directly proportional to the pressure industry felt
to develop substitutes.

     Kathleen Gaillner of Koppers Company said that no substitute had been
found for coke oven door jambs.  They require materials which are flexible
and can withstand temperatures of 2000°F.   She added  that the aluminum
industry had also been looking for substitutes, but had not located  them.
Mike Wright suggested that if a company let it be known that  they required
specifications for an end-use, a substitute could be  found.   A representative
of Dupont responded that simply looking at  end-use may not be enough, because
often the product and/or the application change.  He  estimated a  time  frame
of about 3 years to develop a substitute for an application of this  sort.
                                      217

-------
     Al Weiner stated  that  the Navy had decided  to use non-asbestos products
where possible.  Jack Reed  of Amatex said that his company had a textile
product which is rayon treated with phosphazine.  It decomposes at tempera-
tures of 400-500°F.  It will burn, but extinguishes when the flame is
removed.  It costs approximately $3.50 per pound.

     For electrical insulation, Bal Dixit reported that Zetex was adequate for
thermal and electrical insulation.  It has a lower (less than one-half of
the time) thermal conductivity than asbestos.  Dupont produces Nomex which
is limited to 220°C.
                                     218

-------
                SUMMARY OP THE ROUNDTABLE DISCUSSION ON SUBSTITUTES FOR
                               ASBESTOS-CEMENT SHEET
PANEL MEMBERS

     Dale Ray — (Moderator), CPSC

     David Cogley — GCA Corporation
     Elliot Foutes — CPSC
     Hope Pillsbury — EPA, Office of Pesticides and Toxic Substances

     Dale Ray of CPSC and Hope Pillsbury of EPA opened the discussion with a
brief background description of the purpose of the roundtable discussions.
David Cogley of GCA Corporation also invited comments on GCA's Summary Report
on Substitutes for Asbestos, which had been distributed to participants.  The
following is a synopsis of the discussion on various points.

     Dennis Kelleher and Sid Speil of Johns-Manville* had comments on the
Summary Report on Substitutes.  They asked what level of the supply chain
the cost figures were for, in Tables 10 and 11.  They commented that the
figures were misleading and offered to supply the correct figures.  John Jones
of Cem-FIL and Frank Fekete of GRC Corporation also offered to supply
corrections to the figures.

     Michael Vaudreuil of ALCOA wanted information about asbestos-free
marionite.  He commented that ALCOA has found that asbestos-free marionite
was a feasible substitute for asbestos-containing marionite,  except in the
largest diameter mold sizes, for which the asbestos-free product degraded
more rapidly.  Representatives from Johns-Manville asserted that all non-
asbestos products degrade more rapidly than substitutes.

     A.R. Frederick of General Electric commented that his company uses
A/C sheet, in thicknesses of V-2", for electrical boards, circuit
breakers, etc.  A/C sheet is used because it is strong, and has high
electrical and heat resistance.

     Representatives from Johns-Manville said that flat A/C sheet is used
in schools and residential buildings.  They also said that fiberglass-
reinforced plastic, in corrugated sheet form, can be used in cooling towers.
They said that glass-reinforced concrete (GRC) is less wind-resistant than
A/C sheet.

     John Jones of Cem-FIL described GRC.  It contains glass fibers from
y-lJs" long.  They are uniformly distributed in the matrix.  A variety  of
fillers can be used in this product.  Typical ingredients are  Portland
cement, marble dust, and glass fiber.  GRC can be used outside for  siding
and other weather-resistant uses.
 *
  Hereafter  called  representatives from Johns-Manville.

                                      219

-------
      Representatives from Johns-Manville asked Frank Fekete  (of GRC
 Products)  and John Jones to supply design figures  and ultimates for GRC.
 John Jones replied that GRC can be used in place of  most  applications of
 A/C sheet.  GRC's machining characteristics are not  as good  as those of A/C
 sheet;  although GRC can be drilled and bolted it tends to chip.   Its heat
 resistance is not as good as that of transite, which is produced  by Johns-
 Manville.   Portland cement which is used in their  standard GRC products,
 dehydrates at temperatures higher than 500°-600°.  Now Cem-FIL is working
 with high--"luminum cement (refractory cement) .  It has been  tested to 1000°F.
 Transite is good at 600°F.  John Jones also noted  that their Portland cement
 product has only 5 percent fiber, as compared to A/C sheet which  has 12-
 18 percent fiber.

      Representatives from Johns-Manville asked John  Jones about the strength-
 aging effect^  They stated that they had information that glass in cement
 deteriorates after 5 years.  They asked if this had  improved?

      John Jones replied that his company has field data showing the
 durability of GRC over 12 years.  It starts out with a strength of 4,000 psi,
 and stabilizes after 4-5 years at 2,000 psi.

      Representatives from Johns-Manville said they had information that the
 limit of proportionality for GRC is about 1200 psi.   John Jones replied that
 GRC has been tested in the tropics, in temperate zones, and  in the desert,
 by Pilkington Brothers in conjunction with the British government.  The
 original GRC showed that the 28-day strength was 4,000 psi and the strength
 after 4-5  years was 2,000 psi.   The improved GRC now has  a long term strength
 of 3,000 psi.  Representatives from Johns Manville said that GRC  weakened with
 time down  to the strength of unreinforced cement.  John Jones disagreed with
 the above  statement.

      Representatives from Johns-Manville commented that the  limit of
 proportionality of A/C sheet goes up with age.  They also commented that the
 design  limit for GRC was 870 psi but that A/C sheet  was about 1000 psi.

      John  Jones of Cem-FIL reported that Fiberglass-reinforced plastic is
 used in corrugated form in cooling towers.   It is  also used  as a  skylight in
 industrial buildings.   It is stronger than A/C sheet,  but flexes  more.

      John  Jones of Cem-FIL noted that there are 2  manufacturers of GRC sheet.
 Thirty  companies in the United  States make other types of GRC products, but many
 of  them, such as some  of those  manufactured for architectural uses, are not
 replacements  for A/C sheet.

      Representatives from Johns-Manville described cement-wood board.  It is a
 cement  product  with a  high wood content.   Its high cellulose content absorbs
moisture,  thus  the sheet tends  to expand and  contract  a lot.  Similar
problems with expansion have been experienced with cellulosic roofing felt
and other  products  with high organic  content.
                                     220

-------
     Cement-wood board is used for interior applications because it is light
and flexible.  It is similar to masonite except that it has a Portland
cement binder rather than a resin binder.   It is used in roof underlayment
in countries with low supplies of wood.   It has weathering characteristics
similar to those of marine plywood.  They also commented that cement-wood
board, when used as fill in cooling towers, would ruin the efficiency of the
cooling towers if the material warped.   Cement-wood board used in one cooling
tower in the northwest United States is  now being replaced with A/C sheet.
John Jones of Cem-FIL has supplied GRC for use as cooling tower fill, however
not the GRC product which is made of Portland cement.

     David Cogley asked if A/C sheet is  prevalent in ovens, safes, and
heaters?  Has GRC been used behind wood  stoves?

     John Jones of Cem-FIL commented that GRC has been used around furnaces;
though not necessarily the GRC made with Portland cement.  This GRC is made
with a refractory cement which has a light-weight filler, so that it does not
explode with heat.  The GRC made with Portland cement may explode if exposed
to a rapid change in temperature.  A/C sheet may also explode if it is not
porous enough.  GRC can be installed behind stoves if it is U.L. rated.
Concrete Design Specialties in East St.  Paul, Minneapolis makes GRC for use
behind wood stoves.  Energy Research and Development Corporation makes
ceramic fiber board for the same use.  One can buy it now through Johns-
Manville (Ceraboard), Carborundum, and other companies.  The cost of these
substitutes is 2% times the price of asbestos-containing millboard.

     Representatives from Johns-Manville stated that GRC cannot be used in
highly corrosive environments such as ceilings in paper mills, where there
is much moisture.  John Jones of Cem-FIL asserted that in those cases it  is
the cement that gives out.  Representatives from Johns-Manville said that
metal reinforcement cannot be used in the above environments.

     Dale Ray of CPSC asked if there are any applications for which we are
not close to an adequate substitute for A/C sheet?  Hope Pillsbury added
that laboratory table tops might be an example of-such an application.  John
Jones of Cem-FIL said that there may be no comparable non-asbestos product
for laboratory table tops.  Slate exists but it is inordinately expensive.

     Hope Pillsbury asked if any of the more expensive substitutes could
become cost effective with economies of scale.
                                                         »
     Representatives from Johns-Manville replied  that A/C  sheet is better
than other products in terms of life cycle cost.

     John Jones of Cem-FIL said that economies of scale with greater sales
of GRC should lower the price of this material, although not  to the  level of
A/C sheet, because glass fiber is more expensive  than asbestos fiber.  John
Jones expects that the price of GRC could decline to within  20 percent of the
price of A/C sheet.  In Europe, a nonasbestos GRC sheet  called Tak-board  is
produced at the same price of A/C sheet, but Tak-board is  an inferior material.
                                     221

-------
      Dale Ray of CPSC asked to what extent can existing capital equipment be
 used to produce substitute materials or products?

      Representatives from Johns-Manville said that in Europe they have  looked
 for substitutes for asbestos for 20 years.  They also noted that existing
 machines used to make A/C sheet require flexible fibers in order to work.

      The representative from the Suzorite mica association said that  people
 are developing complex mixtures that can be run on existing machines.   The
 Hatscheck machine is used most often, but the Fourdrinier and Magnani
 machines can also be used.  The Magnani is used for corrugated board  in
 Denmark.  He also said that mica runs quite well through the machines.   It has
 good drainage characteristics, therefore it has been able to substitute for
 crocidolite and amosite.

      The representative from the Suzorite Mica Association said that  a  law
 has been passed in Japan requiring reduction of asbestos content in A/C sheet
 to 5 percent down from 12 percent.

      In Denmark and Sweden laws have been passed banning asbestos.  Viable
 substitutes have not been found for A/C sheet.  Some work on a small  scale
 but there are reproducability problems on the large scale.  Many contain
 some asbestos.

      Irv Huseby of General Electric said that his company is looking  for a
 substitute for transite in arc-shoot applications.  The modulus of rupture
 is 3,000-12,000 for that material.  The substitute they are looking for
 must have a modulus of rupture of 7,000 psl on a 2" stand.  It must also
 pass a 3-point bend test.  A/C sheet can pass these tests.  Someone asked
 if they had tried wollastonite.  Irv Huseby said that it acts like a
 ceramic.

      Lauren Choate of NYCO, a division of PMI asked what was the rupture
 strength before the wollastonite broke.

      John Jones said that there are international building standards  for A/C
 cement;  spacing of supports,  etc.  You need freeze/thaw tests,  hot/dry
 tests,  hot and humid tests, temperate,  and monsoon tests,  etc.

      Lauren Choate said that  wollastonite is used in Denmark.   It is  not
 as  good as asbestos.   Use of  asbestos will be banned after 5 years  in
 Denmark if there is a suitable substitute.

      The  representative from  the Suzorite Mica Association said that  85  percent
 of  the  roofs  in Denmark are made with asbestos.   In the war years asbestos
was not available  so  they used wood fiber.   After 5-20 years the performance
 of  the wood fiber  in  the roofs was not  as bad as expected.   The expansion and
 contraction on these  roofs  was quite large compared with that of asbestos-
containing roofs.

     Barry Castleman,  a consultant,  listed patents which various companies had
on materials which  could  substitute for asbestos.
     *

                                      222

-------
     Dale Ray asked to what extent, existing capital equipment can be
used to produce substitute materials or products?

     The representative from the Suzorite Mica Association said that it costs
$4,000/week to try a new substitute material out on an asbestos-cement machine.
Full-scale tests are necessary because even a small-scale A/C sheet machine
does not give you the correct information.  The total cost of the tests was
about $10,000 for one week.  The equipment to do the job may be valued at
several million dollars.

     John Jones of Cem-FIL said that GRC has been  made on a Hatscheck machine
and a magnani machine.  There can be problems because of glass' tendency
to flocculate.  GRC was not developed as a replacement for A/C sheet.  It
cost several million dollars to develop alkali-resistant glass.  Just a
few percent of this money was directed at developing asbestos substitutes.
A lot more is applied to light-weight concrete substitution than to A/C sheet
substitution.

     A representative from Carborundum said that development of ceramic fiber
board was not aimed at the asbestos-replacement market.  Millions of dollars
were spent on research and development.

     Frank Fekete of GRC Products said that the capital equipment to produce
GRC was brought to the United States from England.  The equipment alone (not
including land or property) cost 1% million dollars.

     Dale Ray asked if energy requirements would be changed substantially by
switching to production or use of the nonasbestos material?  Representatives
from Johns-Manville said the ratio of energy use between producing PVC pipe
and A/C pipe was 4:1.  They also commented that glass fibers take more energy
to make than do asbestos fibers.  The representative from the Suzorite Mica
Association said that mica requires $1.50/ton.

     David Cogley asked if the autoclaving and drying time for A/C sheet  re-
quired a lot of energy?

     A representative from Johns-Manville replied that the more autoclaving
time is used, the less drying time is required, and vice versa.

     Barry Castleman, consultant, commented that Rafael Ramos  Lacen  has re-
ported that polyurethane sandwich panel is used in various housing projects  in
Puerto Rico.  It is used in interior and exterior walls.  It  is not  covered
with an aluminum skin in Puerto Rico and in other developing  countries.

     The representative of the Suzorite Mica Association  said that polyurethane
has extremely toxic by-products of combustion.  If  the cover  is  removed
metal would tend to protect it, but if the plaster wallboard  protecting  it
falls off, then urethane foam is exposed.  This material  is not  a viable
alternative to A/C sheet because of the fire hazard.
                                       223

-------
     Irv Huseby of General Electric said that a fracture/toughness test was
needed such as a 3-point bend test or other similar stress test in order to
rate replacements for A/C sheet.  These tests are done by ceramacists.

     John Jones of Cem-FIL asked if those tests were of slow or impact loads?
Impact tests are run by Cem-FIL.

     Irv Huseby of GE replied that impact tests are a good first start.  Slow
fracture/toughness tests are also needed.  At GE they have been able to re-
place about 10 percent of the uses of arc-shoots with a nonasbestos product.
Polyester-pressed molding would not take the temperatures.

     Supradur makes roofing shingles and siding out of asbestos cement.
                                      224

-------
                   SUMMARY OF THE ROUNDTABLE DISCUSSION ON
                    SUBSTITUTES FOR ASBESTOS-CEMENT PIPE
PANEL MEMBERS

     Richard J. Guimond — (Moderator) EPA,  Office of Pesticides and
     Toxic Substances

     Arlene Levin — GCA Corporation

     Richard McAllister --- EPA, Office of Pesticides and Toxic
     Substances

RANGE OF APPLICATIONS

     Three types of asbestos-cement (A/C) pipe were identified:   pressure pipe
for drinking water, non-pressure pipe for sewers,  and square pipe for air
ducts.

     It was mentioned that at one time A/C pipe was used for food pipes.

     Rectangular-shaped A/C pipe, made only in Europe and used as air ducts,
were discussed.  This pipe is very thick, and its diameter is wide; from 4"
to 36" if not wider.  It is air cured.  Round air duct pipe is also available.

ALTERNATIVE PRODUCTS

     PVC, cement, clay, steel and iron were identified as substitutes for A/C
pipe.  Mr. James Warden of the U.S. Water and Power Resources Services
commented that in a range of up to 24 inches A/C pipe is very competitive
with the substitutes, but above 24 inches the other pipes become competitive,
and above 42 inches A/C pipe is not competitive at all.

     Concrete pipe containing glass fibers was discussed as a possible sub-
stitute for A/C pipe.  Mr. Joseph Jackson, representing the A/C Pipe
Association, made the point that fiberglass, even the alkaline-resistant glass,
does not maintain  its strength in alkaline environments over long periods of
time.  The clay and glass silicates melt when autoclaved; therefore,  fiber-
glass is an impractical substitute material.

     The conclusion of this discussion was that substitutes  for asbestos-
cement pipe are not available in the  form of Substitute fibers, but  rather,
are available only as alternative products such as  concrete  or  steel.  It was
                                      225

-------
 mentioned, though, that a company is developing a wire pipe fiber in which
 about five of these fibers (each about an inch or an inch-and-a-half long) are
 glued together by a soluble glue.  The soluble glue dissolves when the fibers
 are put into the cement, making it easier to handle.  This is being tested for
 concrete pressure-pipe applications.  It was also thought that a German
 company, named Eternit, was researching a new fiber that had the same
 properties as asbestos.

      Concrete is used for pressure-pipe applications up to 150 feet a  head,
 and diameters from 12 inches up to 132 inches.  PVC, ductile iron,, concrete,
 and steel are used for pressure pipe.  Clay pipe is not used for pressure
 applications.  Someone asked whether any pipe that was used for pressure
 applications could also be used in sewers.  Someone replied that metal pipes
 would not' be used in sewers because of the inversion process.  It was
 concluded that concrete, clay, fiberglass, and plastic pipe could be used
 for non-pressure pipe.  Someone said that plastic pipe had half of the
 market, however, when challenged, revised his statement to conclude that
 plastic pipe has a large share of the market.

      Mr. Young Joe of Substitute Abrasion, mentioned a fiber containing 10-
 15 percent carbon fibers and also glass fibers or ceramic fibers, for  use
 in pipes.   Someone commented that they thought inclusion of carbon fiber
 would increase the costs of the pipe so it would be no longer marketable,
 but Mr. Joe said the fibers increased the cost of the pipe only slightly.  He
 commented that the cost of the carbon fiber was in the $6-8 range.

      Mr. Barry Castleman listed some patented fibers such as a cotton-
 reinforced center product made by GAF; a Japanese patent from Asahi Glass  Company,
 which is a reinforcing material for cement sheet, containing glass, cotton,
 and silk;  a sulphur aluminum used in cement; a resistant mineral from
 Sweden; and a coated resistant glass fiber from Johns-Manville.

      Someone commented that the materials listed were all fibers used  to
 fortify cement;  these products are all cured naturally, therefore, they
 contain a  porcelain cement binder.  The products are quite alkaline.  The
 commenter  also said that when the matrix in these products is subjected to
 a  temperature in excess of 354 degrees Fahrenheit most of the materials
 mentioned  would  dissolve.   Also,  many of these materials cannot be
 processed  on the same type of machinery that is used to make asbestos
 products.   A fiber will be commercially usable if it can be processed  the
 way A/C pipe is  made,  if it can be autoclaved and still maintain long  term
 strength and reinforcement to meet all of the American Water Works
 Association specifications.

     Pretention  steel  pipe up to  54 inches is the most economical pressure
 pipe.   A/C pipe  is sold in diameters up to 42 inches.

     General  agreement was reached that there are substantial competitive
 products to A/C  pipe for all  the  ranges of pipes.   There was also agree-
ment that  no  fiber is  presently available that could substitute directly for
                                      226

-------
asbestos fiber In A/C pipe, as it is presently manufactured and cured in the
United States.

     Mr. James Warden from the U.S. Engineering and Research Center, U.S.
Department of the Interior, commented that most pipe they put in the ground
of a size 24 inches and less is A/C pipe regardless of the head.  Above 24
inches and up to about 36 inches, the pretention steel pipe is quite
competitive, and above that range all the other types of pipe become
competitive.  A cost-to-performance analysis is important in the selection
of a pipe.  In a municipality, the operational and maintenance costs, or life
cycle costs are Important.

     Equipment costs for'adapting an existing process to a new fiber must be
considered.

     Installation costs will differ from pipe to pipe.  A/C pipe is very
rigid in all sizes, facilitating its installation, whereas, ductile pipe
is non-rigid and therefore more costly to install in larger sizes.

     A/C pipe imports are very low.  There is a captive market for certain
specifications of pipe.

ENERGY UTILIZATION

     Energy is utilized by substitutes in the physical product and in manu-
facturing.  Various associations have calculated their own ratio's of energy
utilization, but these calculations may be biased.  For example, A/C pipe
used 4 times more energy than PVC pipe; 2 times more than concrete pipe; and,
8 times more than cast iron pipe.

RESEARCH AND DEVELOPMENT

     Linings and coatings for pipe are being Investigated to eliminate the
leaching of harmful substances from the pipe itself or the surrounding area
into whatever material is conveyed in the pipe.  A/C-pipe does not corrode
externally but might corrode internally in aggressive water.  TCE can leach
out into water.  Sometimes coal-tar pitch, asphalt (petroleum-based) and
steel can be used as (external) coatings.  A perfect lining has not been
found.

PRODUCT SPECIFICATIONS

     There are no pipe specifications or generic standards.  Pipes are made
to meet the criteria of the American Water Works Association  (AWWA)  or the
American Society for Testing and Materials  (ASTM).
                                     227

-------
               PRODUCT AND SUBSTITUTE MATERIAL REVIEW SESSION
     The purpose of the Product and Substitute Material Review Session was to
provide a forum in which any expert on a substitute for asbestos fiber or an
asbestos-containing product could present information about the substitute.
Those who were interested in participating in this session were sent guidelines
informing them what type of information they should supply.  The following,
are the edited excerpts from information supplied to EPA,  organized alphabeti-
cally by the name of the organization submitting the information.  The data
presented are believed to be correct, but EPA cannot guarantee their accuracy.
It should also be understood that EPA and CPSC do not endorse any products.
                                     229

-------
COMPANY NAME  Amatex Corporation
              1032 Stanbrldge St.
              Norristown, Pa.  19401
PRODUCT NAME  Nor-Fab and Thermoglass Industrial Textiles
APPLICATIONS
     Nor-Fab
          Yarns                       Cords
          Roving                      Braided tubing and packing
          Filler                      Twisted and braided ropes
          Tapes                       Fabric
     Thermoglass Textiles
          Cloth applications
               Lagging                Flange and valve covers
               Welding shields        Spray shields
               Fire blankets          Stress relieving
               Laminating             Protection of flexaust hose in steel mills
          Tape applications
               Pipe, meter linea and hose wrapping
               Oven door seals
               Fabricating tadpole gasketing
               Thermal insulation
               Pipe hangers
          Tubing applications
               Protection of metal tubing, thermocouple leads,  hose lines,
               wire and cable
               Stress relieving
               Oven door seals and thermal insulation
          Rope applications
               Packing for furnace doors,  boilers
               Core tadpole tape
                                     230

-------
       Suitable  for:

       •     Nor-Fab  could  replace Commercial  Grade  and Underwriters'  Grade
             asbestos material (75 to 80 percent  asbestos  content).

       •     Thermoglass could replace  asbestos products from Commercial  Grade
             through  AM grade (75 to 95 percent  asbestos  content) .

       Situations substitute  not adequate:

       •     Nor-Fab  not suitable to replace high grades asbestos  such as AA
             and  AAA  grade  materials.

       •     Thermoglass not suitable for  temperatures  above  1000°F.

PHYSICAL PROPERTIES/PERFORMANCE/TEST RESULTS

       Nor-Fab
             TYPICAL PROPERTIES
                          Color
                   Fiber Make-up
                Mildew Resistance
              Abrasion Resistance
                Stretch Resistance
                       Flexibility
                      Workability
                  Heat Resistance
                    Color Change

                     Weight Loss
                Strength Retention
 Light Yellow
 Non-asbestos
 Excellent
 Very Good
 Very Good
 Very Good
 Excellent
 Excellent to 650'F
 Darkens at high
 temperature
 Very slight to 650'F
 Excellent to 500°F
              DATA—22PT7 CLOTH—within 10%
                   Breaking Load
                     	(Travail,
                   Effect of High
                    Temperature

                     Weight Loss
               Strength Retention
                  Specific Gravity
                Soluble Chlorides
                            Ph
              Corrosion & Chem-
                  ical Resistance
              Electrical Resistance
                    ASTM D-257
              Thermal Conductiv-
              ity K—ASTM C-177
              'Thermal Conductivity by
            Guarded Hot Plate Method"
               Total Conductance
               Total Resistance Ft
 Warp—185 Ibs.
_FIII—95lbs.  .
 Does not melt, de-
 composes between
 700'F and SWF
 2% at 660'F
 54%at660'F
 1.51
 Less than WOppm
 7.2
 In compliance with
 MIL-I-24244A
 3.0x70"
       (Btu-ln)
     (Hr'FP* ' F)
 (Av. Temp 77.73'F)
 K= 0.560
 C = 8.08
 Ft = 0.124
         CHEMICAL RESISTANCE-NOR-FAB 22PT7

CHEMICAL
ACIDS
Hydrochloric
Nitric
Sulluric
ALKALIS
Ammonium
Hydroxide
Sodium
Hydroxide

-S CONCEN-
- IRAIION

35
70
70

57
50

TEMP
°f °C

70 21
70 21
70 21

70 21
7021

TIME
HRS

1
1
1

1
1
EFFECT ON BREAKING STRENGTH
£
II
I/I
Wt

X

X



*!





i
>
!!







II
(-* *
II
•*z


X




si
If
OO







Because we cannot anticipate or control the many different conditions under which this information and
our products may be used, we do not guarantee the applicability or the accuracy ol this information or
the suitability of our products in any specific application Users ol our products should make their own
tests to determine the suilabilily of each such product for their particular purpose; The products dis-
cussed are sold without" warranty, either express oT implied, and buyer assumes all responsibility for
loss or damage arising from the handling and use ol our products, whether done in accordance with
directions or not Also, statements concerning the possible use of our products are not intended as
recommendations to. use our products m the infringement of any patent
                                                231

-------
      Thermoglass Textiles

           NONFLAMMABLE:   THERMOGLASS products will not burn  or smolder.

           HIGH HEAT RESISTANCE:   May be used at surface  temperatures ranging
           from 120°F to  1000°F.   Retains 50 percent of tensile strength at
           700°F, and as  much as  25 percent at 1000°F.

           EXCELLENT DIMENSIONAL  STABILITY:  Will not stretch or shrink.  No
           more than 3 percent elongation under  maximum stress.  Retains
           stability even at high temperatures.

           HIGH TENSILE STRENGTH:  Highest strength-to-weight ratio of any
           industrial textile product.

           CHEMICAL RESISTANCE:   Inorganic THERMOGLASS is highly resistant to
           most chemicals.  Will  not rot or mildew.

           EXCELLENT ELECTRICAL PROPERTIES:  High dielectric  strength and low
           constants.

           GREATER FLEXIBILITY:   The very fine filaments  used in making
           THERMOGLASS give it a  high degree of  flexibility.

           FINISHES:  THERMOGLASS textiles can be treated with special
           finishes to meet specific requirements.   These finishes include:
           heat treatment to improve cutting and sewing,  waterproof finish,
           rewet finish,  pre-applied adhesive.   It can also be supplied with
           aluminum foil, Neoprene or vinyl finish.

      Performance Standards

           MEETS U.S.  COAST GUARD REQUIREMENTS:   THERMOGLASS  conforms to U.S.
           Coast Guard requirements for  Incombustible Materials, subpart
           164.009.

           APPLICABLE  SPECIFICATIONS:  Amatex THERMOGLASS products can be
           manufactured to meet U.S.  Government  specification MIL-C-20079
           and  other customer specifications,  as required.  For insulation
           materials with special corrosion and  chloride  requirements,
           THERMOGLASS products can be supplied  in conformance to MIL-I-24244.

COSTS IN PRODUCTION

     Costs of  process changes;   No change required by the users to switch
     from  asbestos  to a  substitute.

     Production costs compared;   Same as  asbestos.

COSTS IN USE

  »  Information not  supplied.

                                     232

-------
          In the case of a government restriction on asbestos,  increased
          production is not expected to reduce costs.

LIFETIME COSTS OF USING PRODUCTS

     Just about equal.

HEALTH INFORMATION

     Thertnoglass;  To the best of our knowledge no health hazards are known
     except possible skin and eye irritation.

     Nor-Fab 400 Series;  Aramid fibers as used for these products are
     supplied by E. I. DuPont De Nemours & Co. and have been tested by them
     for toxicity by skin contact tests on animals and humans.   No toxic
     reactions have been observed.  No reports of skin irritation or other
     health hazards associated with this fiber during extensive market
     development activity.

BIBLIOGRAPHIC INFORMATION

     Thermoglass:

          Owens Corning Fiberglass
          Pittsburgh Plate Glass

     Nor-Fab

          E. I. DuPont De Nemours
          Owens Corning Fiberglass
          Pittsburgh Plate Glass

     Manufacturer's Contact;

          Mr. W. Maaskant
          Amatex Corporation
          1032 Stanbridge St.
          Norristown, Pa.  19401
                                     233

-------
COMPANY NAME
               The Andersons
               Cob Division
               •P.O. Box 119
               Maumee, OH  43537
                                                      ®
PRODUCT NAME   Grit-0'Cobs®, Mix-0'Cobs™, Lite-R-Cobs

APPLICATIONS

     Grit-0'Cobs, Mix-0'Cobs and Lite-R-Cobs corncob products could substitute
for asbestos, all or in part, in the following applications.

     Lost circulation material for oil drilling

     Brake shoe component

     Asphalt coatings and sealants

     Bituminous concrete

     Filler for plastics and flooring

     Filler in paper products

     Component in gasket material

PHYSICAL PROPERTIES/PERFORMANCE/TEST RESULTS

                                                  Mix-0'Cobs   Lite-R-Cobs
Property
Elemental Analysis: Carbon
Hydrogen
Nitrogen
Oxygen
Phosphorous
Sulfur
Potassium
Sodium
Magnesium
Silicon
Iron
Calcium
Aluminum
Barium
Chromium
Copper
Lead
Manganese
Nickel
Vanadium
Zinc
Selenium
Cobalt
Grit-0'Cobs
43.5%
7.9%
0.21%
48.4%
0.021%
0.013%
0.93%
0.14%
0.11%
0.089%
0.013%
0.011%
0.0053%
<0.0001%
<0.0001%
<0.0001%
<0.0001%
<0.0001%
<0.0001%
<0.0001%
<0.0001%
<5 ppb
0.00001%
                                                   44.2%
                                                    7.4%
                                                    0.42%
                                                   47.9%
                                                    0.05%
                                                    0.12%
                                                    0.90%
                                                    0.11%
                                                    0.10%
                                                    0.090%
                                                    0.015%
                                                    0.04%
                                                    0.0054%
                                                   <0.0001%
                                                   <0.0001%
                                                    0.0002%
                                                   <0.0001%
                                                    0.0002%
                                                   <0.0001%
                                                   <0.0001%
                                                    0.0001%
                                                   <5 ppb
                                                    0.00001%
                                                                44.8%
                                                                 6.9%
                                                                 0.62%
                                                                47.4%
                                                                 0.07%
                                                                 0.22%
                                                                 0.87%
                                                                 0.08%
                                                                 0.09%
                                                                 0.090%
                                                                 0.017%
                                                                 0.06%
                                                                 0.0054%
                                                                <0.0001%
                                                                <0.0001%
                                                                 0.0003%
                                                                <0.0001%
                                                                 0.0003%
                                                                <0.0001%
                                                                <0.0001%
                                                                 0.0002%
                                                                <5 ppb
                                                                 0.00001%
                                    234

-------
 SELECTED PROPERTIES AND DESCRIPTION OF PRODUCTS

     Grit-0'Cobs are manufactured from the woody ring of corncobs, Llte-R-Cobs
 are manufactured from the coarse chaff, fine chaff and pith of corncobs, and
 Mix-O'Cobs are produced by blending Grit-0'Cobs and Lite-R-Cobs in a ratio
 suitable for various end uses.  The properties presented herein for Mix-O'Cobs
 assume a 1:1 blend of Grit-0'Cobs and Lite-R-Cobs.  Selected properties of
 the subject materials are listed below.  For additional information on prop-
 erties, uses and methods utilized to obtain test data, please refer to
 "Physical Properties, Chemical Properties and Uses of the Andersons' Corncob
 Products."
TGA
            Property
       Oil Absorption
       Water Absorption
       Bulk Density
       Specific Gravity
       Solubility in
         Acetone
       Solubility in
         Ethyl Alcohol
       Solubility in
         Alcohol-Benzene
       Solubility in
         Benzene
       Solubility in Ether
       Solubility in
         Isopropyl Alcohol
       Solubility in 1%
         Potassium
         Hydroxide
       Solubility in 10%
         Sulfuric Acid
       pH (bulk)
       pH (surface)
Grit-0'Cobs    Mix-O'Cobs    Lite-R-Cobs
   100%
   133%
28 lb/ft3
   1.3%

   2.5%

   5.6%

   9.5%

   0.4%
   0.3%

   0.42%


  18.6%

   2.5%
   4.9%
   7.4%
   300%
   430%
20 lb/ft3
   1.5%

   2.3%

   4.8%

   8.2%

   0.4%
   0.9%

   0.36%


  18.6%

   2.5%
   4.9%
   7.4%
   500%
   727%
12 lb/ft3
   1.6%

   2.1%

   4.0%

   6.8%

   0.3%
   1.4%

   0.29%


  18.5%

   2.4%
   4.9%
   7.4%
     The Thermogravimetric analysis of the Grit-0'Cobs is shown on the next
page.  This should be of assistance in defining the temperature limitations
of corncob products.
                                     235

-------
                                                 THERMOGRAVIMETRIC ANALYSIS
Ni
U>
                                                          Temperature, °C
                                                                                                                1000

-------
RESEARCH AND DEVELOPMENT

     The greatest need for research and development in utilizing corncob
products as an asbestos replacement is in the end product use area.  This
Includes the areas of end product formulation and end product performance.

ECONOMIC INFORMATION

Costs in Production;

     Where a corncob product can be directly substituted for asbestos, there
would be little or no cost associated with process changes.  Where a corncob
product is substituted in part for asbestos, the economics are more complex
because the corncob product is only one of the materials involved in the
substitution.  The costs associated with the latter substitution would be
expected to vary from product to product and from formulation to formulation.

Costs in Use;

     The cost of Grit-0'Cobs, Mix-0'Cobs and Lite-R-Cobs products vary from
roughly 5 to 10 cents per pound depending on the grade, the quantity purchased
and whether it is purchased in bulk or bags.

HEALTH INFORMATION

     A product safety and regulatory compliance bulletin is enclosed.  This
contains health information on corncob products.

BIBLIOGRAPHIC INFORMATION

     Pages 357 through 385 of "Physical Properties, Chemical Properties and
Uses of the Andersons Corncob Products" give bibliographic information on
corncob products.  A copy of this publication can be obtained from the manu-
facturers'  contact.

MANUFACTURERS' CONTACT

     Dr. Kevin M. Foley should be contacted for technical information on
corncob products.  David Vander Hooven should be contacted for information
on price and availability.  The address and phone number of these people is
given below.

          The Andersons
          P.O. Box 119
          Maumee, OH  43537
          (419) 893-5050
                                     237

-------
                                  APPENDIX A

              PRODUCT SAFETY & REGULATORY COMPLIANCE INFORMATION
                         BULLETIN FOR CORNCOB PRODUCTS


 (1)  Chemical Composition of Corncob Products

                                          Grit-0'Cobs®    Lite-R-Cobs®
                              Corncobs      granules        granules

        Cellulose               41%           47%             35%
        Hemicellulose           36            37              37
          Pentose fraction      35            37              35
          Xylan fraction        30            32              30
        Lignin                   67               5
        Moisture                10             7               6
        Protein                  2.5           1.4             4.4
        Fat                      0.5           0.2             0.9
        Ash                      1.5           1.2             1.6

      pH (bulk) 5 (determined in 1 to 4 (w/w) ratio of Grit-0'Cobs granules
      to Water (dist.))

 (2)  Pesticide Residue Information

      A typical analysis of Grit-0'Cobs contained less than 0.02 parts per
 million of aldrin,  gamma-BCH, BHC, chlordane, DDD, DDE, DDT, diazinon,
 dieldrin,  disulfoton,  endrin, ethion, heptachlor, heptachlorepoxide, lindane,
 malathion, methyl parathion, parathion, thimet, thiodan, trithion.

 (3)  Fire  and Explosion Properties

              Property                                       Test Method

 Ignition Temperature
  (Grit-0'Cobs Granules)                          401°F    (ASTM D-1929-68)

 Fire  Point -  Open Cup  (Grit-0'Cobs Granules)     388°F    (ASTM D-92-66)
            -  Closed Cup (Grit-0'Cobs Granules)    396°F    (ASTM D-93-71)

 Flash Point - Open  Cup (Grit-0'Cobs Granules)    350°F    (ASTM D-92-66)
            - Closed Cup  (Grit-0'Cobs Granules)  388°F    (ASTM D-93-71)

Minimum Explosive Concentration                   0.045    (U.S. Bureau of Mines
 .. (-200 Mesh  Grit-0'Cobs Dust Cloud)             oz/cu ft   Report 5624)

                                      238

-------
COMPANY NAME  Carborundum Company
              Insulation Division
              P.O. Box 808
              Niagara Falls, NY  14302
PRODUCT NAME  Ceramic Fiber Paper, Board, Cloth, Rope
APPLICATIONS
     Cloth
          Furnace curtains
          Expansion joints
          Welding cloth
          Pipe and hose wraps insulation (tape and sleeving)
          Equipment and personnel protection
          Maintenance cloth
     Rope
          Door seals - furnace ovens
          Flange and burner gaskets
          Static packings
     Paper
          Electric and thermal insulation for transformer coils
          Thermal insulation for oven appliances (self-cleaning)
          Tap out cones for molten aluminum
          Flat gasketing
          Expansion joint material
          Muffler insulation
     Fiberboard
          Thermal protection in large circuit breakers
          Fireproofing for commercial and residential security boxes,
          safes, and files
          Aluminum pouring trough cover and liner
                                     239

-------
 PHYSICAL  PROPERTIES/PERFORMANCE/TEST RESULTS
      Textiles
           Color  - White
           Composition  -  Alumina/silica
           Continuous use limit  - 2300°F
           Melting point  - 3200°F
           Breaking strength  (rope) - 80 Ibs
           Organic content <-  20  to 25 percent
      Paper
           Composition  -  Alumina/silica
           Organic content -  6 to 10 percent
           Tensile strength - 120 psi
           Burst  strength - A Ibf
           Density - 10 to 20 lb/ft3
           Continuous use limit  - 1300. to 2600°F
           Thermal conductivity  - 0.36 at 400°F
      Board
           Composition  -  Alumina/silica
           Continuous use limit  - 2300°F
           Tensile strength - 180 psi
           Organic content -  6 to 7 percent
           Thermal conductivity  - 0.53 at 400°F
COSTS IN PRODUCTION
     Information not supplied.
COSTS IN USE
     Information not supplied.
HEALTH INFORMATION
     Not supplied.
                                    240

-------
BIBLIOGRAPHIC INFORMATION

     Not supplied.

MANUFACTURER'S CONTACT

     B.J. Glazier or K.C. Pietak
     Carborundum Company
     Insulation Division
     P.O. Box 808
     Niagara Falls, NY  14302
                                      241

-------
 COMPANY NAME
 PRODUCT NAME
                       *
Celanese Plastics and Specialties Company
26 Main Street
Chatham, NJ  07928
(201) 635-2600

Celiox™ Fibers

      TM
Celiox   fibers are heat stabilized polyacrylonitrile which has
been subjected to a treatment that results in cyclization,
crosslinking and oxygen addition.
APPLICATIONS
      Some  applications  are:

           Protective  garments

           Fire proximity  suits

           Heat resistant  gloves

PHYSICAL PROPERTIES/PERFORMANCE/TEST RESULTS

Typical Celiox Filament Properties

     Density, g/cc
     % Moisture Regain, (65% RH)
     Electrical Resistivity, Ohm-cm
     Tensile Strength
           g/denier
           psi, x  103
     Tensile Modulus
           g/denier
           psi, x  10
     Elongation,  %
     Color

Response of Celiox to Heat

     Limiting Oxygen  Index
     Flammability in Air
     AATTC Method 5903
     Melting Point
                                   1.4
                                  10
                                 >1010

                                   1.7
                                  30.5

                                  90
                                   1.6
                                  10
                                  Black
                                   50% 02  required to
                                   sustain ignition

                                   Does not ignite
                                   No  afterglow
                                   Zero char length

                                   Converts to  carbon
                                   Sublimation  Point 6600°F
                                   (3650°C)
                                     242

-------
     Exposure to Molten Metal*

          Aluminum @ 1400°F

          Steel <§ 2850°F
Runs off fabric at 70° angle,
no burn through
Runs off fabric at 70° angle,
no burn through
Horizontal fabric withstands
1 Ib. spash without burn
through
Other Properties
     Celiox fibers may be readily converted into carbon fibers.   High tempera-
tures convert Celiox fiber from a heterocyclic polymer to pure carbon.  The
reaction is rapid at temperatures above 600°F (360°C).  Under controlled
conditions, the carbon fiber can develop strength and modulus several times
that of the starting fiber but at a sacrifice in elongation.  Carbon fabrics
find uses as reinforcement of ablative and structural composites for high
temperature service in aircraft disc brakes and rocket nozzles.

RESEARCH AND DEVELOPMENT

     Information not supplied.

COSTS IN PRODUCTION

     Information not supplied.

COSTS IN USE

     Has processability on conventional textile equipment.

HEALTH INFORMATION

     Not supplied.

MANUFACTURER'S CONTACT

     Mr. W.D. Timmons
     Celanese Plastics and Specialties Company
     26 Main Street
     Chatham, N.J.  07928
                    TM
  Gentex Dual-Mirror   aluminized fabric, 13 oz/yd2 Celiox fiber.
  Gent ex Corp., Carbondale, Pa.
                                     243

-------
COMPANY NAME  E. I. DuPont de Nemours and Company, Inc.
Wilmington, DE 19898
PRODUCT NAMES Kevlar®and Nomex®Aramid Fibers
PHYSICAL PROPERTIES/PERFORMANCE/TEST RESULTS
FIBER/FORM:

PHYSICAL PROPERTIES FILAMENT
Density, gm/cc 1.45
Denier/Filament 1 . 5
Filament Dia., mils .47
Filament Length, Ins. Cont.
Tenacity, gm/denier 22
Tensile Strength,
psi x 10- 3 400
Modulus, psi x 10" 6 10
Elongation, % 4
THERMAL PROPERTIES
Shrinkage % at
177°C. (350°F)
285°C. (545°F)
In flames
(815°C. or 1500°F)
Max. Continuous use
Temp. °C
OF
Decomposition
Temp. °C.
op
KEVLAR® NOME3
STAPLE CHOPPED,
YARN PULP FILAMENT
1.45 1.45 1.38
1.5 1.5 1.5
.47 <.47 .50
1.5-4.0 .08-. 25 Cont.
9-13 £22 5.3

160-230 <400 100
10 10 2.5
5 4 22


0
0.5

0.5

150-205
300-400

-480
-900
:®
STAPLE
YARN
1.38
1.5
.50
1.5-3.0
3.5-4.5

65-80
1.3-2.2
35-22


<1.0
2.5

>40

205-260
400-500

-425
-800
     Limiting Oxygen
        Index (LOI)
29
29
                                    244

-------
                                DISC BRAKE PADS
                      -7
                  2.6-
                      -6
     2.0-
         -5
 Md         hp-hr
            WEAR
WEAR |SJA RATE
RATE   ^
                  1.0-
                  0.5-
                              I


                            /

                           / COMMERCIAL
                         / ASBESTOS BASED
                      -3
                                                    CONTROL
                                 TRUCK BLOCK
                                 IIX WITH !
                                 KEVLAR*
                                                    • MIX WITH 2*4
                      - 2
                      - I
                                MIX C WITH
                                5% KEVLAR*

                                > GMSEMI
                                METALLIC
400
204
             900  600
             260  316
              700   800
              371   427
                                               900  1000  *F.
                                               482  538  *C
                                DRUM TEMPERATURE
                            High temperature  wear


.6
0 C
5
LL. ,1
fe
i- .3
E
U n
It'
° 1
<-> .1
0
BASELINE
200eF±20eF
(93-c±irc:

	 •-.
___^
M

_

-APPL. NO.
5 10 15
I l i


.6
O i-
5
Of Jl
u-.l
u.
O
1 "Z
ft"
—.2
y^
S.1
n
FIRST RUN
FADE RECOVERY


^ rTr^^^
~s^
i— —

—

— DRUM TEMPERATURE
250 350 150 550 150 350 250T
1 1 1 1 1 1 1 1 l l 1 1 1



" c
P5
LJ
O
i_ 3
5'
—.2
j_
LU
ILJ. 1
n
WEAR TEST
100°F ± 20'F
~ (201°C ± U°C)

^^^^.^ — • — 1_



	

— APPLICATION NUMBER
10 20 30 10 50 60 70 80 90
1 1 1 1 1 1 1 l 1
               121
COEFFICIENT OF FRICTION
Oh-* *4 v*i «• in en
SECOND RUN
FADE RECOVERY
X
DRW TEMPERATURE
250 350 150 550 650 550 159 350 250T
' ' ' t I- I. 1 1 I l l l i i i i i
.6
sr
u.
o
S'3
I-2
LU
S.I
0
FINAL BASE-
LINE 200°F±
" 20'F
(93°C±irC)
APPL, NO.
" 5 10 15
l i 1
121   176   232
343   238   232   176  121'

 J661A test  plots (Chase test)

                  245
                                                                     	 MIX A*


                                                                     	 MIX A' WITHOUT
                                                                           KEVLAR* FIBER

                                                                      	 PREMIUM COMMER-
                                                                            CIAL ASBESTOS
                                                                            CONTROL

-------
                                                    KEVLAR* ARAMID FIBER
to
•e-
a\
APPLICATION:

PERFORMANCE

Fiber Content, %
Specific Gravity
Coef. of Friction
Friction Fade
Wear Resistance
Wear on Mating
  Surface
Thermal Conductivity
Creep
Coef. of Thermal
  Expansion
Thermal
Fabrics
(Gloves &
Curtains)
Clutch
Facings
Brake
Pads
Friction
Papers
Gaskets
(Beater -
Add &
Compressed)
Plastics
Reinf mt .
100
1.45
N/A
N/A
Excellent
N/A
low
N/A
20-30
1.6-2.2
.2 - .6
Stable
Excellent
low
low
low
2-5
1.6-2.2
.2 - .6
Stable
Excellent
low
low
low
5-15
1.6-2.2
—
Stable
Excellent
low
low
low
3-6
1.5-2.0
N/A
N/A
—
low
N/A
low
                                   N/A
low
low
low
low
                                                             2-50
                                                             1.3
                                                             N/A
                                                             N/A
                                                             Excellent

                                                             low
                                                             N/A
                                                             low

                                                             low

-------
                                  NOMEX  ARAMID
     APPLICATION:

     Product Form:

         PERFORMANCE

     Specific Gravity
     Coef. of Thermal
       Expansion
     Thermal Conductivity,
       BTU. in/hr. ft. 2 °F
     Dielectric Strength,
       Volts/mil
     Resistance to Acid
     Resistance to Caustic
     Resistance to Solvent
     Limiting Oxygen Index
  Thermal
Insulation

  Fiber
Protective
  Clothing

  Fiber
Electrical
Insulation

  Fiber
1.38
low
.24
N/A
Good
Good
Excellent
29
1.38
Low
.24
N/A
Good
Good
Excellent
29
.3-1.38
Low
.3 - .8
850
Good
Good
Excellent
24-32
 COST IN PRODUCTION

      Information not  supplied.

 COST IN USE

                       KEVLAR<8> ARAMID FIBER  (1980 or ices)
APPLICATION;

Fiber Price, S/lb.
Lifetime Cost,
 Asbestos • 1.00
Thermal
Fabrics
(Gloves &
Curtains)
5.75
1.00


Clutch
Facings
5.50
.60-1.00


Brake
Pads
3.75-5.00
.60-1.00


Friction
Papers
3.75
1.00
Gaskets
(Beater -
Add &
Compressed)
3.75
1.05-1.50


Plastics
Reinfmt.
3.75-5.75
1.00-1. 10
                                 NOMEX® ARAMID
  APPLICATION;

  Product Form:

  Price, $/lb.
  Lifetime Cost,
    Asbestos  =  1.00
Thermal
Insulation
Fiber
6.10-19.00
.90 - 1.20
Protective
Clothing
Fiber
6.10-19.00
1.30 - 1.50
Electrical
Insulation
Fiber
6.43-14.26
1.50-3.00
                                       247

-------
HEALTH  INFORMATION

KEVLAR*8 Aramid  Fiber Material  Safety  Information

Kevlar®aramid  is an aromatic, organic composition of carbon, hydrogen,
oxygen  and nitrogen.  When burned,  its combustion products are similar to
those of other  organic materials comprised of the same four elements; their
exact composition depends on the conditions of combustion (temperature,
availability of oxygen, etc.).  Kevlar®yarn is not readily biodegradable
and contains no significant percentage of material extractable in water so
its effect on ground water in  case  of landfill disposal should be negligible.

Kevlar®yarns as supplied by Du Pont have been tested for toxicity by skin
contact tests on animals and humans.  No toxic reactions have been observed.
We have received no reports of skin irritation or other health hazard associ-
ated with this  fiber during six years of extensive market development activity
involving millions of pounds of fiber used in a variety of applications.

Kevlar®is not  radioactive, is stable in all recommended use environments and
requires no special spill procedures.  In handling yarns of Kevlar^ operators
should  be cautioned of the unusually high strength of this product and the
resultant possibility of cuts  to hands or fingers caught in loops and tangles.

NOMEX®  Aramid Fiber Material Safety Information

Nomex®aramid is an aromatic organic composition of carbon, hydrogen, oxygen,
and nitrogen.   Nomex® is difficult  to ignite and will usually self extinguish
in the  absence  of an external  heat  source.  However, when burned, its combus-
tion products are similar to those  of other organic materials comprised of the
same four elements; their exact composition depends on the conditions of
combustion (temperature, availability of oxygen, etc.).  Nomex®is not readily
biodegradable and contains no  significant percentage of materials extractable
in water so its effect on ground water in case of landfill disposal should be
negligible.

Nomex® fiber supplied by Du Pont has been tested for toxicity by skin contact
tests on animals and humans and by  inhalation and feeding tests on animals.
No toxic reactions have been observed.

Nomex®fiber is not radioactive, is stable in all recommended use environments,
and requires no special spill  handling procedures.

BIBLIOGRAPHIC INFORMATION

     Not supplied.
                                     248

-------
MANUFACTURER'S CONTACT
          ®
For Kevlar  Aramid Fibers

     John C. Norman
     Textile Fibers Department
     Centre Road Building
     Wilmington, DE 19898
     Phone: (302)999-3546

For Nomex  Aramid Fiber

     Isaac L. Gadsden
     Textile Fibers Department
     Centre Road Building
     Wilmington, DE 19898
     Phone: (302)999-3951
                                       249

-------
 COMPANY NAME  Evans  Products  Company
               Forest Fiber Products Group
               Glass  Fiber  Division
               1115 S.E.  Crystal  Lake  Drive
               Corvallis, OR  97330
               (503)  753-1211

 PRODUCT NAME  EVANITE Glass Fiber

      EVANITE Glass Fiber is produced  in bulk  form for  the manufacture on
 100  percent  glass paper  and as a furnish additive for  cellulose and synthetic
 media.   EVANITE  fibers are produced by a rotary flame  attenuation method as
 discrete filaments of varying length.  The  fibers are  available in 12 grades
 ranging from 0.30 to 9.00  microns  in  diameter.  EVANITE  fiber is free of
 binder  and surface sizing  additives.  Water content  is negligible.

 APPLICATIONS

      EVANITE has been used since 1976 for the manufacture of 100 percent
 glass fiber  paper and as a cellulosic furnish additive to enhance sheet
 characteristics.  Due to the  wide  range of  fiber grades  available, EVANITE
 may  be  used  for  such applications  as:

      •    High Efficiency  Filtration  Media  (HEPA)
      •    Medium Efficiency Filtration Media

      •    Industrial and Surgical  Respirator  Media
      •    Battery Separators
      •    Cryogenic  Insulation

      •    High Efficiency  Thermal  and Acoustical Insulation

      •    Corrosion  Resistant Media

      •    High Temperature Media

      The coarser grades of EVANITE may be used as a  partial replacement for
chopped strand in many applications.

Furnish Additives

     EVANITE may be used as an additive to  standard  cellulosic furnishes to
improve or modify various  sheet  characteristics, including:

     •    Porosity

     •    Tear Resistance

     •    Machine Shrinkage

     •    Wet Tensile Strength
                                     250

-------
     •    Pulp Drainage Rate
     •    Dimensional Stability
     •    Drying Rate
     •    Bulk
PHYSICAL PROPERTIES/PERFORMANCE/TEST RESULTS
Glass Fiber Grades
     EVANITE Glass Fiber is available in the following standard grades:
                                              Average fiber
                                           diameter* (microns)
                                                  0.30
                                                  0.45
                                                  0.60
                                                  0.75
                                                  0.90
                                                  1.60
                                                  2.70
                                                  3.20
                                                  4.50
                                                  5.70
                                                  7.20
                                                  9.00

GLASS COMPOSITIONS
     The fiber grades are produced from two borosilicate glass compositions
distinguished primarily by their ability to withstand acid attack:
     •    B Glass—Standard borosilicate.  Normally specified for
          Grades 0250-2500.
     •    C-Glass—A special, acid resistant composition normally
          specified for Grades 3000-9000.
Grade
0250
0500
1000
1500
2000
2500
3000
4000
5000
6000
7000
9000
Reference

AAAA

AAA
AA

A
B
C
D
E
G
*Based on typical average values as determined by EP tests 02-006  and 02-003
 calibrated by actual SEM observation.
                                     251

-------
 PROPERTIES

                                          B-Glass        C-Glass

               Specify Gravity             2.55           2.50
               Service Temperature         545°C          565°C
               (Estimated)

               Softening Point*            703°C          735°C
               *ASTM C 338.

 CHEMICAL DURABILITY

      The EVANITE C-glass composition was developed  specifically  to withstand
 extremely harsh acid environments.   Both glass  compositions perform relatively
 well in mild alkaline conditions.   Performance  data,  as  determined by EP
 Method 03-002*, are:

            Glass        Acid        Alkaline

              B          10.0           8.0          Maximum %

              C           2.0          11.0          Weight Loss
            *72  hour Immersion at  77°C

            Acid-1.28 s.g.  HaSOi,

            Alkaline-ph 10  NaOH

     Weight loss associated with  immersion  in  excess of  72 hours is
negligible.

SERVICE TEMPERATURE

     Depending  on the  level of product  shrinkage tolerable, EVANITE may be
used at elevated temperatures in  excess of  500°C.  EVANITE has also been
successfully tested  at  cryogenic  temperatures.

PAPER MAKING CHARACTERISTICS

     The EVANITE fiber  grades have been developed for use on conventional
paper making equipment with only minor  adjustments necessary to deal with
differences in drainage rates, drying time, and shrinkage characteristics.
                                     252

-------
DISPERSION

     EVANITE disperses exceptionally fast and with a minimum energy input.
Every attempt should be made to agitate with care.   Beater speed and time
should be set at the lowest levels necessary to produce a homogeneous
slurry.  In this manner, fiber damage will be minimized and the resulting
sheet characteristics improved.

     EVANITE disperses optimally at a water temperature range of 28 to 32°C
and pH 2.8 to 3.5.  However, the fiber can be easily dispersed at near-
neutral pH.

CONSISTENCY

     Fiber concentration should be maintained at minimal levels to reduce
fiber damage caused by abrasion during beating.  Consistency levels of
approximately 0.75 to 1.00 percent in the mixer and 0.05 to 0.10 percent at
the headbox are desirable.

COSTS IN PRODUCTION

     Information not supplied.

COSTS IN USE

     Cost of EVANITE glass fiber as of May 15, 1980.

             Grade        Price/lb        Grade        Price/lb

             0250          $7.79          3000          $1.14

             0500           6.23          4000           0.93

             1000           3.26          5000           0.67

             1500           2.34          6000           0.66

             2000           2.18          7000           0.65

             2500           2.00          9000           0.63


HEALTH INFORMATION

     Not supplied.

BIBLIOGRAPHIC INFORMATION

     Not supplied.
                                     253

-------
MANUFACTURER'S CONTACT

     Alan J. Gnann
     Evans Products Company
     Forest Fiber Products Group
     Glass Fiber Division
     115 S.E. Crystal Lake Drive
     Corvallis, OR  97330
                                     254

-------
COMPANY NAME  GRC Products, Inc.
              17051 IH 35 North
              Drawer J
              Schertz, Texas  78154
              (512) 651-6773
PRODUCT NAME  GRC Flat Sheet
     GRC is an asbestos-free Glassfiber Reinforced Cement product made by
reinforcing a mixture of ordinary Portland cement and a fine aggregate, with
alkali-resistant glass fiber.  The glass fiber used for the reinforcement of
the cement matrix was developed by the British Research Establishment and
Pilkington Brothers, Limited of St. Helens, Merseyside, England, to resist
the alkali produced during the normal setting and hydration processes in
Portland cement.
APPLICATIONS
     A few of the many applications of GRC are:
          Carrier board for laboratory tunnel tests
          Electric closet linings
          Fire resistant linings
          Industrial wall partitions
          Fume hood liners
          Lost form work
          Tunnel linings
          Commercial and industrial use as spandrels, soffits, fascia panels
          Commercial and industrial sandwich panel wall systems
          Pizza oven liners and shelves
          Highway noise control/noise barrier
          Rooftop walkways
          Livestock products
               Feed troughs
               Sheep dips
               Pig slurry channels
               Insulated pig pen slabs

     GRC has satisfactory performance at high  temperatures  for  short periods
of time.  The maximum service temperature  of GRC is  in excess of 600°F.
                                     255

-------
 PHYSICAL PROPERTIES/PERFORMANCE/TEST RESULTS
      GRC has properties similar to those of asbestos-cement with one notable
 exception; impact strength, in which GRC is approximately 10 times stronger
 than asbestos cement.  All current GRC formulations will satisfy ASTM 136 as
 regards noncombustibility and will be rated 0 on all characteristics measured
 by ASTM E84.
      The results of tests performed on GRC by an independent outside testing
 laboratory are listed below:
      Dimensions of test coupon - 1/4" x 2 1/4" x 14"
      Dry Density, PCF - 124.2
      Normal moisture content (% of dry weight) - 2.3
      Water absorption (% of dry weight) - 4.9
      Modulus of elasticity, PSI - 2.4 x 106
      Transverse strength, PSI (MOR) - 3300
      Compressive strength, PSI - 18,000
      Tensile strength, PSI - 2200
      Shear strength, PSI - 5300
      Brinnel hardness - No. 29
      Dimensional change due to moisture (in./in.)
           Shrinkage - normal to dry - 0.0014
           Expansion - normal to 90% RLF - 0.0004
           Expansion - dry to saturated - 0.0015
           Thermal expansion (in./in./°F) - 1.3 x 10~6
      Maximum service temperature in excess of 600°F.
      All  tests  and calculations were performed in accordance with ASTM
 standards C-220,  C-459,  and C-580.
 PERFORMANCE STANDARDS
      At this  point of time,  there are no government or industrial performance
 standards to  be met by the GRC  product.
 RESEARCH  AND  DEVELOPMENT
      Although GRC is  being evaluated as  a substitute  product in many areas,
 the basic material (glass  fiber reinforced cement)  is backed by over 12  years
 of service and laboratory  testing;  consequently,  GRC  is considered a developed
material.
                                    256

-------
COSTS IN PRODUCTION

     GRC sheet can be cut and machined with tools suitable for masonry and
asbestos cement use.  Fabrication of GRC should not require retooling or
supplying of new equipment.

     Except for the actual price differential between GRC and Asbestos Cement,
there should be no change in production costs of using GRC over asbestos cement,

COSTS IN USE

     A full range of GRC flat sheet is commercially available.  Standard
thicknesses of 1/8, 1/4 and 3/8 inch are available from inventory in
4 foot by 8 foot sheets and 4 foot by 10 foot sheets.

     GRC sheets are priced on a per square foot basis.  Our current quantity
prices are as follows:

     •    1/8 inch - $0.60 ft2

     •    1/4 inch - $0.80 ft2
     •    3/8 inch - $1.05 ft2

(These prices subject to change without notice.)

     There is no question that with further restrictions or a total restric-
tion of the use of asbestos cement sheets resulting in an increased produc-
tion of GRC, the price of CIRC could decrease by as much as 15 to 20 percent.

     GRC, having the same excellent general properties as asbestos cement
sheet, such as good mechanical strength and chemical resistance, rot proof,
fire resistance, heat resistance, and good machining qualities, should
perform comparably to asbestos cement sheets with essentially no increase
in cost of installation, maintenance and replacement.

HEALTH INFORMATION

     The reinforcing material of GRC, Cem-Fil AR glass fibers, do not
present any known health hazard during manufacture, installation, on-site
working or long term weathering.

BIBLIOGRAPHIC INFORMATION

     Additional commercial and technical information on GRC can be obtained
from the following sources:

          Pilkington Brothers, Ltd.
          Cem-Fil Marketing
          St. Helens, Merseyside, England

          Cem-Fil Corporation
          120 Spence Lane
          Nashville, Tenn  37211
                                     257

-------
MANUFACTURER'S CONTACT

     GRC Products, Inc.
     17051 IH 35 North
     Schertz, Texas  78154

          Mr. Frank W. Fekete
          Mr. Bill Lewis
                                     258

-------
COMPANY NAME  Hill Brothers Chemical Company
              One City Blvd. West,  Suite 1521
              Orange, California  92668
PRODUCT NAME  HiFibe
APPLICATIONS  (for HiFibe in general)
     •    Caulks Sealants
     •    Gasket Forming Compounds
     •    Cements
     •    Filler in Plastics
     •    Swimming Pool Plaster
     •    Interior and Exterior
            Plaster and Stucco
     •    Polyester Resin Filler
     •    Putty
     •    Glazing Compounds (Window)
     •    Crack Filler
•    Asphalt Coatings and Cements
•    Textured Paints
     Underbody Spraying Mastic
•    Mastic
•    Block Fillers
•    Joint Cements

•    Paints
•    Vinyl Moulding Compounds
•    Taxidermy
•    Fiberglass Boats
PRODUCT NAME  HiFibe 250, 270, 290
     Description
          HiFibe 250, 270 and 290 are high fiber content fillers.  The fiber
in these fillers is HiFibe 2000 which has been dispersed in an inert filler.
The method of dispersion insures a very uniform product which does not sep-
arate upon mixing.  These fillers work well in either water or oil-based sys-
tems and show very low shrinkage upon drying.
APPLICATIONS  (for HiFibe 250, 270, 290)
     As a fibrous filler in cements, caulks, puttys, taping muds, and poly-
ester resins.  In asphalt coatings, textured paints, mastics, glazing compounds,
and anywhere a high fiber content filler is needed.
RESEARCH AND DEVELOPMENT
     We have a staff of chemists working on new formulations and uses of
HiFibe.
                                     259

-------
PHYSICAL PROPERTIES/PERFORMANCE/TEST- RESULTS

      Specifications                    250          270          290

           Bulk density  (Ib/cu.  ft)       39           39           37
           Oil  absorption                88          106          110
           Water absorption               84          100          112
           Burn rate                   Fiber chars, will not sustain flame
           Moisture content             <1%          <1%          <1%
           Color                      White        White        White
           %  fiber                        5%           7%           9%
           %  inert fillers             -95%         -93%         -91%

      Limitations

           HiFibe should not be  used where temperatures exceed 115°C.

      Physical  Properties

           The  fiber  content of  HiFibe varies from 1 percent to 100 percent by
weight.

           Another major component of HiFibe is C. P. California talc from
Pfizer Minerals.  The grades  of fibers used in HiFibe have average lengths
from  0.7 mm  to 2.5 mm with an aspect ratio of about 20.  These fibers have
average  coarseness values between 7 and  15 decigrix (1 decigrix = 1 mg/100 mg)
This  is  equivalent to 0.6 to  %  denier.   The branched or fibrillated nature of
the fiber  results in a  very soft flexible fiber.

           HiFibe is  not designed to resist abrasion, acid and base corrosion
or as a  noise  and thermal insulation.

COSTS IN PRODUCTION

      There should be no additional costs for retooling, equipment changes,
etc., as no  process  change would be anticipated.

COSTS IN USE

      Depending upon  the application, HiFibe will cost about the same as, to
twice the  cost of using asbestos.  Depending primarily upon the percent of
synthetic  fiber in the  HiFibe,  the cost  of the product at our Los Angeles
plant would  be 12$ to $2.00 per pound.

      If  the  government  chose  to restrict the use of asbestos, this would not
change the price appreciably.

      If used as recommended,  the product produced with HiFibe should have a
lifetime cost  the same  as asbestos.
                                    260

-------
HEALTH INFORMATION

     It is Hill Brothers Chemical's belief that all inhaled dust can be harm-
ful, therefore, we recommend that a dust respirator be worn when handling
HiFibe to avoid inhalation of the dust.

BIBLIOGRAPHIC INFORMATION

     The fiber used in HiFibe is high density polyethylene.  A booklet titled
"Fybrel Synthetic Fiber" published by Crown Zellerbach, Chemical Products
Division, Vancouver (Orchards) Washington, 98662, describes a HiDensity
Polyethylene Fiber in detail.

MANUFACTURER'S CONTACT

     Contact Mr. Dean Hill, International Headquarters, Hill Brothers Chemical
Company, One City Boulevard West, Suite 1521, Orange, California  92668,
phone, Area Code 714, 634-3322.
                                      261

-------
 COMPANY NAME  HITCO Materials Group
               1600 W.  135th Street
               Gardena, CA  90249

 PRODUCT NAMES  Refrasil (silica textile products)
                Carbon  and graphite continuous  filament  yarns

 REFRASIL/TECHNICAL CHARACTERISTICS

 Applications

      •    Weld Protection

      •    Furnace Curtains
      •    Personnel Shields
      •    Separator Cloth

      •    Expansion Joints
      •    Thermocouple Insulation
      •    High Temperature Seals/Gaskets

      •    Hose and Cable  Insulation

      •    Furnace Linings
      •    Reformer Insulation Containments

      Generally speaking,  Refrasil can be substituted  for asbestos in the
 same  textile product form and provide increased  insulation and thermal
 stability  in higher temperatures.   Standard Refrasil  products can withstand
 temperatures to 1800°F, whereas asbestos Commercial and Underwriters Grades
 are only rated at 450°F.

      Refrasil is  not recommended for safety clothing  or protective garments
where  seam strength and flexing are critical to  the integrity of the garment
and safety of the wearer.   The  low break strength and abrasion resistance
of Refrasil  cloth restricts the application in safety garments to accessories,
such as aprons, gauntlets,  leggings, etc., where seam strength and abrasion
are not critical  to the performance of  the article.

PHYSICAL PROPERTIES AND PERFORMANCE CHARACTERISTICS

     •    Chemical  analysis  - 96 percent minimum SiC*2,  traces
          of metallic oxides.

     •    Temperature  limit -  1800°F before embrittlement occurs.

     •    Thermal Conductivity - 0.6 Btu/hr/ft2/in./°F  at 400°F
          to 1.5 Btu/hr/ft2/in./°F at 1800°F.
                                    262

-------
     •    Specific Heat - 0.28 Btu/lb/°F average

     •    Linear Shrinkage - 2 percent to 12 percent depending upon peak
          temperature ranges from 800°F to 1800°F.

     •    Chemical Resistivity - relatively inert to most chemical
          environments, including acids, except flourine gases and
          some molten metals such as magnesium, sodium and silicon.

     •    Permeability (UC 100-96 cloth) - 5.3 cu ft/min/sq ft.

     •    Abrasion Resistance (UC 100-96 cloth) - 229 cycles.

     •    Dielectric Strength - 40 volts/mil

     •    FTM Std. 191, Method 5304 Wyzenbeck Unit,  2 Ib load, 2 Ib
          tension, 600 grit paper.

For complete properties and performance characteristics of Refrasil, refer
to "Technical Data Bulletin - Engineering Data LHT/MD-3979R."

PERFORMANCE STANDARDS

     •    MIL-I-24244 Chloride Acceptability

     •    40 CFR 164.009 Incombustible Materials

     •    NNSY 383/IM Refractory Cloth, 2000°F intermittent service,
          nonasbestos (Norfolk NSY).

RESEARCH AND DEVELOPMENT

     The areas in need of improvement in the silica textile products include
abrasion resistance and break strength.  The material provides thermal per-
formance to 1,800°F and beyond (with special treatments), but fails to pro-
vide the durability to withstand the normal industrial environments.  Various
surface coatings and impregnations have been applied in an effort to improve
abrasion resistance and lubricate the individual fibers to reduce failure from
flexing.

REFRASIL/ECONOMIC INFORMATION

Costs in Production

     In most instances, there is no need for process changes when  substituting
Refrasil for asbestos textiles in the same form  (cloth, tape,  sleeving,  etc.).
The elimination of costs for asbestos compliance usually result in a reduction
of overall costs, in spite of the higher  (two  to three times)  initial cost  of
material for Refrasil over asbestos products.
                                    263

-------
 Costs in Use

      The average selling prices of Refrasil in the various product  forms
 available are:

           Cloths - $14 to $28/lineal yard

           Tapes - $0.40 to $1.60/lineal foot
           Sleevings - $2.25 to $5.50/lineal foot

           Yarns and Cordages - $26 to $36/pound
           Fiber - $10/poiind
           Batt - $3.75 to $4.50/square foot
           Rope - $0.25 to $5.00/lineal foot

 Prices vary within product forms due to variables of thicknesses, sizes, and
 quantities purchased.

      Costs of producing Refrasil are directly related to the costs  of  raw
 material (leachable glass fiber textile products) and labor.  Current
 pricing policies of the weaver and glass fiber producers do not  indicate
 any cost reductions from increased production volumes.

 REFRASIL HEALTH INFORMATION

      Due to the size of Refrasil fibers (8 microns in diameter)  the possibility
 of  inhaling fibers into the lower respiratory tract is minimized.   Therefore,
 it  is believed that with reasonable precautions applied to the handling and
 use of Refrasil, no health hazard or concern for safety exists.  Reference
 "Technical Data Bulletin - Safety and Health Considerations" LHT/MD-3879
 for complete data.

 CARBON AND GRAPHITE CORDAGE/TECHNICAL CHARACTERISTICS

 Applications

      Compression packings (braided)

      High  Temperature .door seals

      Vacuum furnace lining thread

      The primary use for carbon and  graphite filament yarns is in the
production  of braided mechanical packings  for service temperatures  above
550°F and highly corrosive environments.   Due to the presence of TFE and
other organics  that  serve as  lubricants for braiding,  these products are
not recommended  for  applications where  high-purity and  nonhalogens  are a
requisite  (such  as nuclear applications).
                                    264

-------
PHYSICAL PROPERTIES AND PERFORMANCE CHARACTERISTICS
                                     Carbon           Graphite
      Carbon assay (wt %)               92                 99
      Ash Content (wt %)                0.5                0.5
      Breaking strength (Ib)       15 (10 ply)       30 (20 ply)
      Diameter (in.)               0.05 (10 ply)     0.08 (20 ply)
      Yield (yd/lb)                700 (10 ply)      350 (20 ply)
      Modulus (lb/in.2 x 106)             6                  6
      Tensile (lb/in.2 x 103)            120                120
      Chloride content                   -          Less than 50 ppm
Carbon and graphite cordage resists chemical attack except from highly
oxidizing substances.
COSTS IN PRODUCTION
     Generally, there are no process or manufacturing changes required for
carbon and graphite braiding operations.  The packing manufacturers may
vary lubricants and other additives as it applies to their specific braiding
process or equipment.
COSTS IN USE
     The carbon and graphite yarns are expensive, but intended for special
high-performance braided packings or seals.  The average selling prices are:
     •    Carbon cordage (10 ply) - $25/lb
     •    Carbon cordage (20 ply) - $22/Ib
     •    Graphite cordage  (10 ply) - $35/lb
     •    Graphite cordage  (20 ply) - $32/Ib
     The superior thermal performance and chemical resistance  of carbon and
graphite materials allows substitution for asbestos in more  critical valve
and pump sealing applications with the assurance of longer more reliable
service and less frequent replacements due to thermal or corrosion failures.
Overall cost comparisons with asbestos .packings may be available from  the
braided packing manufacturers.
                                    265

-------
HEALTH INFORMATION

     Carbon and graphite cordage materials are electrically conductive and can
cause interference to electronic signals and communications.  Consequently, pre-
cautions against indiscriminate disposal of materials are advisable.

BIBLIOGRAPHIC INFORMATION

     For complete properties and performance characteristics of Refrasil,
refer to "Technical Data Bulletin-Engineering Data LHT/MD-3979R."

MANUFACTURER'S CONTACT

     Robert E. Portik,
     HITCO Materials Group
     1600 W. 135th Street
     Gardena, CA  90249
     (213) 321-8080
                                     266

-------
COMPANY NAME  Janos Industrial Insulation Corporation
              80 West Commercial Avenue
              Moonachie, New Jersey  07074
PRODUCT NAMES  Nu Board 1800
     This is an asbestos-free board made from mineral fibers and silica.
              Thermonol Textiles
     These are replacements for commercial grade asbestos cloth, uscable for
temperatures up to 650°F.
              Glastemp Textiles
     This line of glass textiles can replace asbestos up to AA grade.
              Siltemp Textiles
     This is a product line of high-temperature textiles for replacement of
AAA grade asbestos.  It can be utilized for temperatures up to 3000°F.
              Cem-Fil GRC/125
     This product ds being used as a replacement for asbestos-cement sheets.
It is manufactured in the same sizes, and can also be molded to fit various
specifications.
              Glasspaper
     This product is being utilized to replace asbestos paper rolls  for the
home consumer.
APPLICATIONS
     Some typical uses  for Nu Board 1800
     •    Lining furnaces                   •   Cores for metal clad doors
     •    Moving picture booths             •   Stove pads* welding  pads
     •    Elevator shafts                   •   Incinerators
     •    Ceilings, walls exposed  to heat  •   Heater  lining
     •    Gaskets                           •   Strongbox  lining
     •    Stoves                            •   Kiln lining
     •    Electric ovens                    •   Molded  for troughs
     •    Glass Lehr rolls                  •   Cable protection
     •    Float glass conveyor  rolls
                                     267

-------
     Uses for Thermonol Textiles
     •    protective garments, weld curtains, insulation barriers,
          insulation pads, sleeving for thermocouples, cable tapes,
          gaskets for wood-burning stoves.
     Uses for Glastemp Textiles
     •    weld shields, gaskets, stress relieving applications,  safety
          blankets, protection of flexible hose, door seals, tadpole
          gasketing, packing furnace doors.
     Uses for Siltemp Textiles
     •    same as listed above only for higher temperatures.
     Uses for Cem-Fil GRC/125
     •    mounting of electrical equipment, bakery ovens, casings
          over boilers, cooling towers, skirting on buildings,
          machined parts.
     Uses for Glasspaper
     •    wrap paper for fire protection, protection for soldering,
          welding, lining barbecue pits, wrapping gas tanks for storage,
          iron rests, muffler wrap.
PHYSICAL PROPERTIES/PERFORMANCE/TEST RESULTS
Physical Properties of Nu Board 1800 (nominal);
     •    Color - Beige
     •    Density - 66.8 lb/ft3
     •    Tensile strength - 711 lb/in.2
     •    Flexural strength - 1280 lb/in.2
     •    Compression at 3000 psi - 30 to 40 percent
     •    Ignition loss - 20 percent max
     •    Moisture content - 3 percent
     •    Thermal conductivity - 0.0636 Btu/hr/ft/°F
     •    Flammability - Will not burn
     •    Heat resistance - Up to 1800°F dependent upon application
     Dimensions
     •     Thickness  range - inclusive 3/32" to 1/2"
     •     Sheet  size - 40" x 40"

                                    268

-------
COSTS IN USE

              Nu Board 1800

     20 to 25 percent higher than the existing asbestos sheets, however, it
has a longer life at higher temperatures.

              Thermonol Textiles

     Approximately 10 to 15 percent above asbestos prices.

              Glastemp Textiles

     5 to 10 percent higher than asbestos price.

              Siltemp Textiles

     Approximately 30 to 35 percent higher than asbestos.

              Glasspaper

     Approximately same as asbestos.

COST IN PRODUCTION

     Information not supplied.

HEALTH INFORMATION

     Not supplied.

BIBLIOGRAPHIC INFORMATION

     Not supplied.

MANUFACTURER'S CONTACT

     T.J. Connolly
     Janos Industrial Insulation Corporation
     80 West Commercial Avenue
     Moonachie, New Jersey  07074
                                      269

-------
 COMPANY NAME .  Manning Paper Company
                P.O. Box 328
                Troy, New York  12181

 PRODUCT NAME   Manniglas 1200, 1400, 1270,  1276,  and 1277 material

 APPLICATION

      Application examples:

           Manniglas 1200 and 1400 have an Underwriters'  Laboratories  94V-0
 recognition and are suitable products where this  test criteria  is important
 to the end product.

           Pneumatic tube bundle heat protection wrap light  fixture heat shields
 when laminated to aluminum foil.

           Hand held hair dryers and other appliance heat shields with and
 without foil lamination.

           Components of tape composites for high  temperature  cable wrap.

           Manniglas 1276 for skin applications on:

           (a)   urethane and isocyanurate

           (b)   rigid foam boards—vinyl laminations substrate to impart
                flame barrier

           (c)   glass bat or compressed mat  flameproof surface skin to
                impart smoother surface

 PHYSICAL PROPERTIES/PERFORMANCE/TEST RESULTS

      Glass fiber  temperature limitations are in the 1300-1500°F range.  At
 these temperatures  the product will soften  and the  glass will melt at 1500°F.

      Glass fiber  papers are lower in density than asbestos  fiber papers and
 consequently are  a  much lower actual weight.   Usual estimates are one-third
 the weight range  of the asbestos  materials  and therefore overall coverage
 costs  are  usually competitive with current  asbestos materials.

PERFORMANCE  STANDARDS

     Manniglas  1200 and 1400 have an Underwriter's  94V-0 recognition.

RESEARCH AND DEVELOPMENT

     Information not supplied.
                                     270

-------
COSTS IN PRODUCTION

     Information not supplied.

COSTS IN USE

     Cost varies from lie to 13$ per square foot, depending on thickness of
the material.

HEALTH INFORMATION

     Not supplied.

BIBLIOGRAPHIC INFORMATION

     Not supplied.

MANUFACTURER'S CONTACT

     John M. North
     Manning Paper Company
     P.O. Box 328
     Troy, New York  12181
     (518) 273-6320
                                     271

-------
COMPANY NAME   NEWTEK INDUSTRIES, INC.
               P.O. Box 25
               Victor, New York  14564

PRODUCT NAME   ZETEX™

APPLICATIONS

     Curtains:    welding, fire, drop, oven

     Blankets:    stress relieving, welding, thermal insulation,
                  safety

     Industrial:  expansion joints, electrical insulation,
                  piping insulation, gas and liquid filtration,
                  scrubbers, acoustical insulation, reinforcements,
                  laminates, folded and rubberized gaskets.

     Safety:      garments, gloves, mittens, spats, sleeves,
                  aprons

     Engineered
       Products:  door seals, tad-pole gaskets, pads, etc.

Applications in which the product may not work are those in which cut-resis-
tance of the material is required; e.g., gloves and mittens.  The products
can be reinforced with leather or an additional layer of ZETEX as is com-
monly done with asbestos.

PHYSICAL PROPERTIES

     Content:  Silica-based highly textured yarn

     Fiber shape and size:  Round with 6 to 9 micron filament

     Dielectric characteristics:  Dielectric constant of 5.9 to 6.4

     Strength:  500,000 psi at 72°F

     Elongation:  Approximately 5% for yarn

     Resistance to abrasion:  Taber abrasion tester, CS17 Wheels,
                              1000 Gm/Wheel

                              ZETEX 1200 - 493 cycles to failure

                              ZETEX 1200XP - 1812 cycles to failure
                                     272

-------
     Chemical resistance:   Unaffected by most acids,  alkalies,
                           solvents,  dilute sulfuric  acid (with
                           exception  of hydrofluoric  acid and
                           corrosive  environments at  elevated
                           temperatures).

     Thermal insulation:    Thermal conductivity is less than
                           one-half that of asbestos.  The
                           thermal conductivity or K-value for
                           ZETEX 1200 is 0.3385.

     Leachable chlorides:   Less than  0.5 parts per million.

PERFORMANCE

     Specific gravity:  2.54

     Breaking strength of fabric:  350 to 500 Ibs/inch

     Tensile modulus for fiber:  10.5 x 106

     Coefficient of linear expansion:  2.8 x 106

     Specific heat for fiber at 72°F:  0.197

RESULTS OF TESTING

     Physical testing conducted in accordance with the appropriate
     ASTM standard.

     The leachable chlorides were done according to military
     standards MIL-1-24244.

PERFORMANCE STANDARDS

     Various military and government specifications  are written
     for asbestos.

RESEARCH AND DEVELOPMENT

     Is required in the areas of fiber  and finishes.

ECONOMIC INFORMATION

     a.   No process changes required  that we  know of.

     b.   Production costs of using  ZETEX  are  almost identical to
          those of asbestos except in the  safety garment field where
          they may be higher by  about  20%.
                                     273

-------
     c.   Costs in use:  the price of ZETEX fabrics is about $5.00
          to $16.00 per sq/yd to distributors and $7.00 to $22.00
          per sq/yd to the end user.

     d.   If the government chose to restrict the use of asbestos
          the increased production of ZETEX would cause a decrease
          in prices of ZETEX products by up to 30%.

     e.   Depending on application and use, the lifetime cost of
          using ZETEX products can be lower than asbestos.  In
          safety products* such as gloves and mittens, the cost
          may be 60 - 80% higher than asbestos products.

HEALTH INFORMATION

     Transient mechanical irritation

MANUFACTURER'S CONTACT

     Mr. David Moore
     Newtex Industries, Inc.
     P.O. Box 25
     Victor, New York  14564
     (716) 924-9135
                                    274

-------
COMPANY NAME  Scan-Pac Manufacturing Company
              9950 N. Port Washington Rd.
              Mequon, Wisconsin  53092
PRODUCT NAME  Complete line of nonasbestos friction materials  for clutches
              and brakes of all types.
TECHNICAL CHARACTERISTICS
     Applications
          Scan-Pac has available and is selling nonasbestos friction materials
for a myriad of uses, some of which are:
          Garage door openers                   Winches
          Lawn mower clutches                   Cranes
          Rider mower brakes and clutches       Shovels
          Snowmobiles                           Presses
          Paper machines                        Trucks
          Wire rope machinery                   Fork lifts
          Fishing reels                         Buses
          Snowthrowers                          Industrial clutches
          Medical equipment                     Electric motors
          Machine tools                         Hoists
     Physical Properties
          Content;  Depends on compound and see Health Information.
          Fiber Shape and Size;  Chopped glass fibers of approximately
          13 microns diameter.
          Dielectric Characteristics;  Not applicable.
          Strength;  Excellent, but varies with compound.
          Flexibility;  Some  compounds  flexible, some rigid.
          Resistance to Abrasion;  Excellent.
          Resistance to Corrosion;  Not applicable.
          Noise;  Very quiet  brake.
          Moisture Absorption;  Virtually none.
     Performance
          Specific Gravity;   Varies by  compound from 1.7 to 2.6.
          Tensile Strength;   Varies by  compound;  typical 2400-5000.
          Coef. of Friction;   Varies  by compound  from 0.12 to 0.60.
                                      275

-------
      Results iof Testing

           All products Chase machine tested per SAE J 661 (see reference 1
 and 2 under Bibliographic Information for method of testing and test results).

      Performance Standards

           Five truck block formulas are certified by American Association of
 Motor Vehicle Administrators.

      Research and Development

           Most of the research and development has been done.  Dry mix and
 Wet mix materials research started in 1976 and is still continuing.  Product
 line information can be found in references 1 and 2 under Bibliographic
 Information.  Additional R&D on these items requires more equipment such as
 dynamometers, experimental molds, experimental grinders.  R&D to complete the
 line has been underway for about 1 year.  This includes conversion of all
 asbestos items to nonasbestos shown in reference 3 of the Bibliographic
 Information.

 ECONOMIC INFORMATION

      Costs in Production

           The costs of nonasbestos process changes to users is basically the
 cost of new molds.  The cost to Scan-Pac is molds, changes in existing equip-
 ment and/or new equipment.  In both instances cost is dependent upon size of
 finished parts.

           Scan-Pac's production costs are somewhat higher due to nature of
 components.  We estimate 10 to 20 percent.

      Costs in Use

           Due to the vastly different sizes of finished parts (see Technical
 Characteristics) and the number of different materials  (see Appendix A, B,
 and C), it is impossible to assign prices per ton, foot, etc.

           We estimate that 20 to 35 percent premium over asbestos product is
 realistic.

           It is doubtful that a government ban on asbestos would lower this
 percentage, as all components of nonasbestos friction materials are normally
 produced for other applications.

           The lifetime cost of using the nonasbestos product should be lower
 than asbestos, due to elimination of precautions that must be taken when
 installing or replacing asbestos.  In addition, nonasbestos friction provides
.longer  lining life plus less wear on mating parts.
                                      276

-------
HEALTH INFORMATION

     Scan-Pac's nonasbestos compounds do not contain any materials on Toxic
Substance Control list.  The raw materials are basically the same found in
asbestos friction materials, with deletion of asbestos fiber, and addition
of chopped strand glass fiber.   The size of the glass fiber (13 micron diam-
eter) is such that it cannot be respired into the human lung.

     Scan-Pac's nonasbestos line can fulfill many needs that many asbestos
compounds cannot, such as:

     1.   Longer lining life

     2.   Less wear on mating surfaces
     3.   Full range of friction characteristics

     We do not know of situations where our materials are not adequate.

BIBLIOGRAPHIC INFOBMAIION

     The following references are available from the manufacturer:

     1.   Scan-Pac Nonasbestos Industrial Friction Materials

     2.   Scan-Pac Nonasbestos Truck Blocks

     3.   Scan-Pac Friction Materials

MANUFACTURER'S CONTACT

     Paul Vandenberg
     Scan-Pac Manufacturing, Inc.
     9950 North Port Washington Road
     Mequon, Wisconsin  53092
                                     277

-------
                        SCOPE OF THE HEALTH WORKSHOP

                                     by

                             James N.  Rowe, Ph.D
                    U.S.  Environmental Protection Agency
                              Washington,  D.C.


     It is my privilege to welcome you to  the National Workshop on Health As-
pects of Asbestos Substitutes, sponsored by the Environmental Protection Agency
(EPA) and the Consumer Product Safety Commission  (CPSC).   It  is appropriate
that we dedicate this workshop to the memory  of the late  Dr.  Mearl Stanton of
the National Cancer Institute.  Dr. Stanton*s invaluable  contributions to our
understanding of the mechanisms of fiber carcinogenesis provide a scientific
basis for the rational design of safe asbestos-substitute products.

     This workshop provides a forum for discussion of the potential hazards of
substitutes, study of the relevant issues, and  productive communication among
the various segments of the scientific community  represented  here, including
industry, academia, public interest groups, and government.   Our work here
should provide the regulatory agencies with helpful guidance  for dealing with
the substitutes issues.

     Asbestos substitutes raise complex health  issues.  This  complexity has at
least four sources:  1) the diversity, and even the definition, of asbestos-
substitutes, 2) our incomplete understanding  of the toxicology and pharmacoki-
netics of fiber and non-fiber particulates, 3)  the limited development of ade-
quate scientific criteria for determining  toxicities  due  to factors 1 and 2,
and 4) the uncertainty involved in the assessment of  quantitative risk to humans
by extrapolation from toxicological data in other species.

     I will briefly comment on each of these  factors.

     The first health related factor is the diversity and definition of asbestos
substitutes.

     Asbestos substitutes deal with a wide variety of materials which may be
simplistically labeled fibrous and non-fibrous.  Within each category,  there
are natural and synthetic substances, each having different physico-chemical
composition, morphological characteristics, and potential for undesirable and
possibly toxic contamination.  The workshop agenda illustrates  this point  and
suggests that the term "asbestos substitute" is open to a variety of  interpre-
tations.
                                      279

-------
      The second factor is our limited understanding of the toxicology and
 phannacokinetics of fiber and non-fiber particulates.

      For example, are short, thin durable fibers (<5 vim length)  completely
 non-toxic and only thin durable fibers (>5 vim length)  toxic or is  there  a
 gradual transition from the ineffective fiber size to  a length which possesses
 maximum fiber toxicity as hypothesized by Pott1?  The  questions concerning  the
 nature of fiber-induced carcinogenicity and fibrosis and the regulatory  deci-
 sions made on these issues have significant impact on  a very large segment  of
 the industrial community including the mineral and chemical industries.  Dr.
 Stanton's observations are critical for proper evaluation of the fibrous sub-
 stitutes.  His work establishes the in situ potential  of a variety of chemi-
 cally dissimilar, durable fibers to produce mesotheliomas in experimental
 animals.  However, the relationship of intrapleurally  produced cancers to
 carcinogenesis produced by inhalation remains to be established.  In inhala-
 tion of particles the lungs normal physiological barriers are involved as well
 as the ultimate biodisposition of the fibers.  In addition, the role of  co-
 carcinogens in fiber and particulate toxicology remains to be further defined.

      The third factor is the need for reasonable scientific criteria for eval-
 uation of asbestos substitutes.

      Because of our limited understanding of the mechanisms of fiber and non-
 fiber induced chronic toxicity, appropriate testing batteries or scientific
 criteria can, at best, provide only a rough approximation of the hazard. In a
 1974 editorial on fiber carcinogenesis2 Dr. Stanton noted that,  "Our present
 systems of assessing carcinogenicity in animals can at best only detect  re-
 sponse to large numbers of fibers; therefore, materials containing only  a few
 exceptionally fine fibers could easily escape detection as a hazard in simply
 designed animal tests.  Even with the most sophisticated test, it  would  be
 difficult to establish an absolute threshold of safety, since each small ex-
 posure possibly adds to the total hazard and represents a finite,  albeit small,
 ultimate risk."  It behooves us to understand the state-of-art for evaluation
 of substitutes and to develop scientific criteria which most accurately  reflect
 that understanding.  This workshop should provide use  with information on the
 health hazards of asbestos substitutes and some thoughts on defining our
 approach to evaluating substitutes.

      Finally we come to the issue of quantitative risk assessment  in humans.

      The last factor relates to the extrapolation of in vivo and in vitro data
 to  humans in environmental exposure situations, i.e.,  quantitative risk  assess-
 ment.  Many scientific issues remain to be settled.  Evaluation of the risk to
 humans remains a necessary but oftentimes difficult function for regulatory
 agencies.   However,  quantitative risk assessment for a material with abundant
 human data  such as asbestos is much less ambiguous since the extrapolation  does
 not  require interspecies  comparisons between animals and man.  This "luxury"
 of scientific  data will not be available for many substitute materials.

     In conclusion,  the EPA and CPSC recognize the complexity of the scientific
and health  issues  related to asbestos substitutes.   However, we also recognize
                                      280

-------
the definite health hazards which may be posed by significant exposure to as-
bestos, and the need to reduce such exposure where possible.  It is therefore
important that the potential health hazards of substitutes and the limitations
of testing information be clearly defined.  Such understanding will allow the
development and application of scientific policy which is both coherent and
equitable.  Such progress should prevent reoccurrence of the tragic disease
manifestations which have occurred and are occurring since the introduction of
asbestos into American commerce in the 1890's.

     I am very pleased by your willingness to participate in this workshop, and
I am confident that our efforts will be productive.

REFERENCES

1.   Pott, F.  Staub-Reinhalt Luft 38(12):486-490.  1978.

2.   Stanton, M.  J.  Nat.  Can. Inst. 59(3):633-634.   1974.
                                     281

-------
            INHALATION, DEPOSITION AND CLEARANCE OF PARTICLES

                                      by

                          Morton Lippmann,  Ph.D.
         New York University  Institute of  Environmental Medicine
                           New York, NY,  10016
                                 ABSTRACT

Inhaled particles can deposit at  airway surfaces all along the respiratory
tract.  For compact particles with diameters >!s urn and for fibers with
diameters £0.2 ym the probabilities of deposition at specific sites, within
specific anatomic regions,  and for the respiratory tract as a whole depends
upon their aerodynamic diameters  and  for  fibrous particles, on their lengths
as well.  The fate of deposited particles, and their abilities to induce or
exacerbate toxic effects depends  critically upon their deposition sites, their
cytotoxicities, their clearance pathways, their storage sites and their chemical
and physical properties.

This discussion focuses on those  properties of asbestos substitutes which are
critical in determining their airborne size distributions, respiratory tract
deposition probabilities, deposition  patterns within the airways, reactions
with epithelial cells and macrophages, and their toxic effects.  Knowledge of
these factors may permit modifications in production specifications and trade
utilization of the products in ways which may minimize the potential for toxic
effects in the utilization of asbestos substitutes.


The major component regions of the respiratory tract differ markedly in struc-
ture, size, function, and sensitivity or  reactivity to deposited particles.
Thus, a complete determination of dose from an inhaled aerosol depends on
(1) the regional deposition, (2)  the  retention times at the deposition sites
and along the elimination pathways, and  (3) the physical, chemical, and bio-
logical properties of the particles.  Here, we will discuss first the factors
that determine the amounts and patterns of particle deposition within the  com-
ponent regions of the respiratory tract and then the pathways and dynamics  of
particle translocation and elimination.   Both discussions will emphasize the
normal patterns of behavior and transport applicable to particles that are not
acutely toxic, but may produce chronic lung disease after extended  periods of
inhalation exposure.
                                     283

-------
 FUNCTIONAL ZONES FOR PARTICLE DEPOSITION

      The respiratory tract (Figure 1) can be divided into zones on the basis
 that insoluble particles that deposit in each zone contact or affect  different
 cell populations and/or have substantially different retention times  and  clear-
 ance pathways.  Each zone includes one or more anatomic regions.  The clearance
 kinetics for particles deposited in each zone will be discussed in greater
 detail under Particle Retention.

      Particles deposited in the unciliated anterior portion of the nose remain
 at the deposition sites for a variable and ususally indeterminate time—that  is,
 until they are removed mechanically by nose wiping or blowing, sneezing,  etc.
 After leaving the nares or nostrils, the inspired air passes through  a web of
 nasal hairs and flows through the narrow passages around the turbinates.   It
 is warmed, and moistened, and is partially depleted of particles with aero-
 dynamic diameters larger than 1 ym by impaction on the nasal hairs, at bends
 in the air path, and by sedimentation.  Particles smaller than 0.1 ym can
 deposit in this zone by diffusion.  The surfaces are covered by mucus.  Most
 of the mucus in this region is propelled toward the pharynx by the beating of
 the cilia, carrying with it deposited insoluble particles.  Soluble particles
 may be dissolved in the mucus.  Some mucus moves toward the anterior  nares,
 carrying inhaled whole or dissolved particles into the zone of intermittent
 mechanical clearance.

      Particles inhaled through the nose and deposited in the nasopharynx, or
 particles inhaled through the mouth and deposited in the mouth and oropharynx,
 are swallowed within minutes.  They pass through the esophagus in or  on the
 mucus coming up from the trachea.

      The tracheobronchial or conductive airways have the appearance of an
 inverted tree, with the trachea analogous to the trunk and the subdividing
 bronchi to the limbs.   The airway diameter decreases distally, but because of
 the increasing number of tubes the total cross section for flow increases and
 the air velocity decreases.   In the larger airways, particles too large to
 follow the bends in the air path are deposited by impaction.   At the  low  veloc-
 ities in the smaller airways,  particles deposit by sedimentation and  diffusion.
 Ciliated and secretory cells  are found at all levels.   Inert, nonsoluble  parti-
 cles deposited in normal ciliated airways are cleared within 1 day via the
 larynx on the moving mucus.1

     The  zone  beyond  the  ciliated  airways is where gas  exchange takes place.
The epithelium is very  thin, and  soluble  particles are  believed to enter  the
pulmonary blood within  minutes.   Insoluble particles deposited in this  zone
by  sedimentation and  diffusion are removed very slowly with clearance half-
times of  days, months,  or years.   The mechanisms for clearing insoluble parti-
cles from the  alveolar  zone are only partly understood, and their relative
importance  is  a matter  of some debate,  as discussed under Alveolar Clearance.

FACTORS AFFECTING PARTICLE DEPOSITION

     Particles deposit  in the  various zones or regions  of the respiratory tract
by a variety of physical mechanisms.   Deposition efficiency in each region

                                      2S4

-------
    OLFACTORY  AREA

      CONCHAE

     VESTIBULE




      TRACHEA.  20mm


        LUNG


    BRONCHUS  8mm
  PULMONARY
   ARTERY

LYMPHATICS
 PULMONARY
   VEIN
    LYMPHATICS
 NASOPHARYNX

 ORAL PHARYNX

EPIGLOTTIS


LARYNX
      BRONCHIAL
       ARTERY
                    LUNG  LOBULE
      LUNG
   TRACHEO- BRONCHIAL
   LYMPH  NODES
   0.5 TO  1.5 cm
   CONDUCTING
   BRONCHIOLE, 0.6mm

     TERMINAL
     BRONCHIOLE, 0.6mm

      RESPIRATORY
      BRONCHIOLE, 0.5mm

      ALVEOLAR
       DUCT, 0.2mm

      ALVEOLAR
      SAC, 0.3 mm

    ALVEOLUS
      Figure 1.  Structure of the respiratory tract,
                            285

-------
 depends on the aerodynamic properties of the particles,  the anatomy of  the
 airways, and the geometric and temporal patterns of flow through them.

 Deposition Mechanisms

      Significant particle deposition can occur within the respiratory tract by
 five mechanisms:  interception, impaction, sedimentation, diffusion, and elec-
 trostatic precipitation.  However, in most cases, only impaction,  sedimentation
 and diffusion will be important.

 Interception—
      Interception usually is significant only for fibrous particles.  It takes
 place when the trajectory of a particle brings it close  enough to  a surface so
 that an edge contacts the surface; thus the particle size must be  a significant
 fraction of the airway diameter.  Fibers 200 ym long have been observed in
 human lung samples.2  Straight fibers, such as amphibole asbestos,  are  more
 likely to penetrate to the alveoli than similarly sized, but curly, chrysotile
 asbestos because the straight fibers assume orientations more parallel  to the
 flow streamlines.

 Impaction—
      Inhaled air follows a tortuous path through the nose or mouth and  branching
 airways in the lung.  Each time the air changes direction, the momentum of parti-
 cles tends to keep them on their preestablished trajectories, which can cause
 them to impact on airway surfaces.  The most likely deposition sites are at or
 near the carinas of the large airway bifurcations.

 S ediment at ion—
      Gravitational sedimentation is an important mechanism for deposition in
 the smaller bronchi, the bronchioles and the alveolar spaces where the  airways
 are small and the air velocity is low.  Sedimentation becomes less effective
 than diffusion when the terminal settling velocity of the particles falls below
 approximately 0.001 cm/sec, which for unit-density spheres is equivalent to a
 diameter of about 0.5 ym.

 Diffusion—
      Submicrometer particles in air move randomly under  the impact of gas mole-
 cules.   This Brownian motion increases with decreasing particle size.   It
 becomes  an effective mechanism for particle deposition in the lung as the root-
 mean-square displacement approaches the size of the air  spaces.  Diffusional
 deposition is  important in small airways and alveoli and at  airway bifurcations
 for particles  smaller than about 0.5 jam.  For radon and  thoron daughters, where
 the particle size is molecular, diffusional deposition efficiency  can be high
 in  the head and in large airways such as the trachea.

 Electrostatic  Precipitation—
      Particles with electric mobility can have enhanced  deposition in the
 respiratory tract even though no external field is  applied across  the chest.
Deposition results  from the image charges Induced on the surface of the airways
 by  the charged particles.   Test aerosols resulting  from  the evaporation of
 aqueous dgoplets  can have substantial mobilities, and the results  of some exper-
imental deposition  studies using such aerosols without charge neutralization
are  accordingly suspect.   Freshly fractured mineral dust particles may  also be
highly charged.                       286

-------
Aerosol Factors

     Particle size is always an important variable in regional deposition.
There are a number of ways of expressing particle size.   In this discussion,
and in most health-related literature, particle size is  expressed in terms of
actual or equivalent diameters.  When particle size is measured by one param-
eter and expressed in terms of another or equivalent size, the basis for the
conversion must be clearly established.  Nonspherical particles are frequently
characterized in terms of equivalent spheres, for example, on the basis of
equal volumes, equal masses, or aerodynamic drag.  A parameter in increasingly
common use is aerodynamic diameter (D), which incorporates both particle
density and drag.

     Aerodynamic diameter is the most appropriate parameter in terms of parti-
cle deposition by impaction and sedimentation, which usually account for most
of the deposition by mass in the head and lungs.   On the other hand, diffusional
displacement, which is the dominant mechanism for particles smaller than % um,
depends only on particle size and not on density or shape.  Interception also
depends on the linear dimensions of the particle, as well as its shape, since
aerodynamic drag can affect the particle's orientation within the airway.

Respiratory and Flow Factors

     An important respiratory factor already discussed as a parameter affecting
deposition is air velocity.  Increasing velocity increases Impaction deposition,
but decreases sedimentation and diffusion by decreasing residence time.  The
flow is cyclical and reverses many times per minute.  At its peak, flow may be
turbulent in the trachea, but the Reynolds number decreases with increasing
lung depth, so that in the smaller conducting airways flow is always laminar,
and in the alveolar region it is always viscous.3

     Since flow is laminar in most of the anatomical dead space, the core
velocity is almost twice the average velocity.  Thus, even in very shallow
breathing, a substantial fraction of the inhaled air penetrates beyond the
anatomical dead space, and particles with appreciable sedimentation rates (e.g.,
particles larger than 2 um) or large diffusional displacements (e.g., particles
smaller than 0.1 um) can deposit efficiently in peripheral airways.

     The tidal volume is an important respiratory parameter.  The air inhaled
at the start of each breath goes deeper into the lung and remains there longer
than the air inhaled later in the breath.  The deeper the air goes and the
longer it stays, the greater the depletion of inhaled particles.  Thus, for
quiescent breathing—where the air velocity is low, mixing is minimal, and the
tidal volume is only two to three times the dead-space volume—a large propor-
tion of the inhaled particles can be exhaled.  Conversely, for heavy exertion,
where larger volumes are Inhaled at higher velocities, both impaction in the
large airways and sedimentation and diffusion in the smaller airways and
alveoli will be greater.
                                     287

-------
Anatomical Factors

     Intrasubject variations in airway anatomy affect particle deposition in
several ways:   (1) the diameter of the airway influences the displacement
required by the particle before it contacts the airway surface; (2) the cross
section of the  airway determines the flow velocity for a given volumetric flow
rate; and (3) variations in diameter and branching patterns along the bronchial
tree affect the mixing characteristics between the tidal and reserve air in the
lungs.  For particles with aerodynamic diameters below 2 urn, such convective
mixing can be the single most important determinant of deposition efficiency.

     There are  also  significant intersubject differences in respiratory tract
anatomy.  For example, the average alveolar-zone airspace dimension has a sub-
stantial coefficient of variation when measured either post-mortem on lung
sections or in vivo  by aerosol persistence during breath holding.  In the
former case, Matsuba and Thurlbeck*1 reported a mean size and variation of
0.678 mm ± 0.236.  In the latter case, Lapp, et al. ,5 found values of 0.535 mm
± 0.211.

Physiological Factors

     In regard  to physiological factors, the effective diameters of the conduc-
tive airways for airflow are defined by the surfaces of the mucous layers.  In
normals, the mucuous layer on the larger conductive airways is believed to be
only about 5 ym thick6 and decreases with airway size.  In terminal bronchioles,
it may be only  0.1 ym thick.7  Hence, the reduction in air-path cross section
by the mucous is negligible.  On the other hand, in individuals with bronchitis,
the mucous layer can be much thicker, and in some locations it can build up and
partially or completely occlude the airway.  Air flowing through partially
occluded airways will form jets, which will probably cause increased deposition
of particles in small airways by impaction and turbulent diffusion.

Other Effects

     No discussion of the deposition of inhaled aerosols would be complete with-
out consideration of the influence of airborne contaminants on the lungs of the
people inhaling the  particles.  Inhaled irritants can affect the fate and tox-
icity of the inhaled particles by altering airway caliber, respiratory function,
clearance function,  and/or the function, survival, and distribution of the cells
which line the airways.  Any reduction in cross section in the larger bronchial
airways increases flow velocities and should, therefore, increase particle depo-
sition by impaction.  Tracheobronchial particle deposition is significantly
greater in cigarette smokers than in nonsmokers,8» »x° presumably because of
the bronchoconstrictive properties of cigarette smoke.

     While some normal cigarette smokers have increased bronchial deposition,
the increase is relatively small compared to that in individuals with clinically
defined, chronic bronchitis.8*11'12  Greatly increased tracheobronchial parti-
cle deposition has also been seen in some asymptomatic asthmatics.8
                                     288

-------
EXPERIMENTAL DEPOSITION DATA

Total Deposition

     Relatively few attempts have been made to measure regional particle deposi-
tion in humans.  A much larger number of studies  have explored total deposition.
For particles between 0.1 and 2 ym aerodynamic diameter,  deposition in the con-
ductive airways is generally very small in comparison to  deposition in the
alveolar regions, and total deposition approaches alveolar deposition.   Total
deposition as a function of particle size and respiratory parameters has been
measured experimentally by numerous investigators.   Many  previous reviews of
deposition have called attention to the very large difference in the reported
results.13'17

     Much of the discrepancy can be attributed to uncontrolled experimental
variables and poor experimental technique.  The major sources of error have
been described by Davies.3  Data from studies performed with good techniques
and precision all appear to show the same trend,  with minimum deposition at
about 0.5 ym diameter.

     The deposition data in Figure 2 by Chan and  Lippmann18 and Stahlhofen, et
al.,19 were based on external in vivo-measurements of y~tagged particle reten-
tion.  This technique was also used by Swift, et  al.20 for tests in the 0.03 ym
size range.

Head Deposition

     Some inhaled particles deposit within the air passages between the point
of entry at the lips or nares and the larynx.  The fraction depositing can be
highly variable, depending on the route of entry, the particles' sizes, and
the flow rates.  In most cases, the nasal route is a more efficient particle
filter than the oral, especially at low and moderate flow rates.  Thus, people
who normally breath part or all of the time through the mouth may be expected
to deposit more particles in their lungs than those who breathe entirely through
the nose.  During exertion, the flow resistance of the nasal passages causes a
shift to mouth breathing in almost all people.

Deposition in the Tracheobronchial Zone

     Figure 3 shows in vivo measurements of tracheobronchial  (T-B) deposition
of normal healthy humans by Lippmann and co-workers,8»15*18»21»22 and Stahl-
hofen, et al.19  T-B deposition for a given particle size varies greatly from
subject to subject among nonsmokers, cigarette smokers and patients with lung
disease.18  Average T-B deposition is slightly elevated in smokers and greatly
elevated in the lung-disease patients.8'1   However, among normals and non-
bronchitic smokers, each individual has a characteristic and reproducible  rela-
tionship between particle size and deposition.  T-B deposition includes both
deposition by impaction in the larger airways and deposition by sedimentation
in the smaller airways.  Impaction deposition predominates for large particles
(diameter larger than 3 ym) and high flow rates  (more than 20 L/min), while
sedimentation deposition becomes a larger fraction of a diminishing T-B  com-
ponent for smaller particles and lower flows.

                                     289

-------
     1.0
    0.8
•35  0.6
 o
 O.
 a>
    0.2
     0
        _   O
Experimental Doto
 Chan and Lippmann
 Swift.etal
 Stahlhofen.etal
     \




             \
 Predictive Models
	Yu
	Davies.etai
	  Heyder.etai
       0.01         0.05  0.1 -         05    1            5    10   20
        Mass Median Diameter /im   ><   Aerodynamic Diameter p.m
     Figure 2.   Experimental total respiratory tract deposition data
                from radioaerosol  studies, and predictive models for
                total deposition.
                                  290

-------
     1.0
    0.8
:!  0.6
 o
 o>
03
    0.4
    0.2
     0
Lippmann
Chan and Lippmann
Stahlhofen, et a[
                          n
       0.01         0.05  Ql
       Mass Median  Diameter
                      0.5   I            5    10   20
                     -*f— Aerodynamic Diameter /im
              Figure 3.  Experimental tracheobronchial (T-B)
                        data for  radioaerosol studies.
                                   291

-------
      For deposition within the tracheobronchial zone,  the pattern of deposi-
 tion within hollow airway casts made from normal human lungs  demonstrates
 the airway bifurcations accumulate a disproportionate  share of  the deposits.   »
 Furthermore, the density of the surface deposition on  the bifurcation regions
 appears to correspond close with the incidence of primary cancer sites.  The
 largest numbers of human lung cancers are found in lobar  bronchi.  Among the
 lobar bronchi, the largest numbers are found at the right upper bronchus and
 the smallest in the right middle bronchus.  Figure 4 shows cast deposition data
 for the lobar bronchi for various particle sizes and flow rates.  While the
 absolute amounts of deposition vary considerably with  particle  size and flow
 rate, the relative amounts on the various lobar bronchi remain  relatively con-
 stant and appear to be closely associated with the cancer incidence reported
 in the pathological literature.

      Figure 5 shows alveolar deposition values obtained in mouth-breathing
 inhalation tests on nonsmoking normals.  These data are based on external
 measurements of the retention of y~tagged particles after the completion of
 the bronchial clearance.  It can be seen that the data of Chan  and Lippmann18
 and Stahlhofen, et al. ,19 are in good agreement, and both sets  of data appear
 to be consistent with the earlier data of Lippmann and Altshuler.22

      Figure 6 shows an estimate of the alveolar deposition that could be
 expected when the aerosol is inhaled through the nose.  The estimate is based
 on the difference in head retention during nose-breathing and mouth-breathing
 from the analysis of Lippman.15  It can be seen that for  mouth-breathing, the
 size for maximum deposition is about 3.5 ym, and that  about half of the
 inhaled aerosol of this size deposits in this region.   For nose-breathing,
 there is a much less pronounced maximum of about 25 percent at  2.5 urn, with a
 nearly constant alveolar deposition averaging about 20 percent  for all sizes
 between 0.1 and 4 um.

      Figure 6 also shows the sampler acceptance criteria  of the British Medical
 Research Council (BMRC)  and of the American Conference of Governmental Industrial
 Hygienists (ACGIH).   These criteria define the cutoff  characteristics of the
 precoHectors preceding respirable dust samplers.   It  can be  seen that both
 provide reasonable approximations of the cutoff characteristics of the human
 conductive airways,  at least those of nonsmoking normals.   The  alveolar deposi-
 tion calculated on the basis of the International Commission  on Radiological
 Protection (ICRP) Task Group's model17 departs significantly  from the deposi-
 tion observed in reliable experimental studies.

      The 1966 Task Group report has been widely quoted and used within the health
 physics  field.   One  of the significant conclusions of  the Task  Group study was
 that  regional deposition within the respiratory tract  can be  estimated using a
 single  aerosol parameter, the mass median diameter.  For  a tidal volume of
 1450  cm3,  there were relatively small differences  in estimated  deposition over
 a very wide  range of geometric standard deviations (1.2 
-------
                                    301pm
   60
£50
o

|40


I30

'I 20
        Right Upper
   10

   0
g

                Right Middle
Right Lower
                                 **.&
Left Upper      Left Lower
                                                                     I
            Aerodynamic Diameter of Test Aerosol and Reported Cancer Incidence
         Figure 4.  Percentage  of total particle deposition within
                    the  five lobar bronchi of the cast which occurs
                    within each lobar bronchus, at a flow rate  of
                    30 L/min, compared with the reported percentage
                    of total lobar bronchial carcinomas which
                    originate within each lobar bronchus.  Data on
                    cancer sites are from Schlesinger and Lippman.2**
                    With permission of Academic Press.
                                     293

-------
     1.0
    0.8
 o  0.6
Q
 5  0.4
 o

^  0.2
    	1	1	1	1
      Experimental Doto    Predictive Models
     • Chan and Lippmann — Yu
     o Stahlhofen.ctd    	ICRP,750ml(1966)
                        —— Lippmann and Altshuler
T	T
0.01         0.05  0.1          0.5
 Mass  Median Diameter /im
                                              I            5    10   20
                                             Aerodynamic Diameter
          Figure 5.   Alveolar deposition data from radioaerosol
                     inhalation studies, and  predictive models
                     for alveolar deposition.
                                   294

-------
    1.0
   0.8
   0.6
J
"J75
   0.4
   0.2
Task Group Model (TSOcc)
                                    Sampler Acceptance
                                        Criteria
                                           IMRC
     0.1    0.2     0.5   1.0     2       5     10    20
                 Aerodynamic Diameter (//m)
 Figure  6.   Comparison  of sampler acceptance curves
             of BMRC and AC6IH with alveolar deposition
             according to an ICRP Task Group,17 and
             from the experimental New York University
             deposition  data of Figure 5.
                           295

-------
 individual, rates of clearance vary greatly from region to  region within the
 respiratory tract.  This variation was a major basis  for the  characterization
 of functional zones described earlier.  In two of these zones—the ciliated
 nasal passages and the tracheobronchial tree-clearance  in normal individuals
 is completed in less than 1 day.  In the alveolar zone, clearance proceeds by
 slower processes, most of which vary considerably with  the  composition of the
 particles.  A detailed discussion of alveolar clearance will  follow  the dis-
 cussion of mucociliary clearance.

 CLEARANCE OF PARTICLES FROM THE CONDUCTING AIRWAYS

      Particles that deposit in the airways that conduct the inspired air to
 the respiratory tissue may be cleared by several mechanisms.  The most impor-
 tant mechanism for insoluble particles is mucociliary clearance.  Particles
 deposited on the surface of the mucous are transported  proximally as the mucous
 is propelled by the rhythmic beating of the cilia. However,  soluble particu-
 lates, depending on their physicochemical properties, may either be  incorporated
 into the mucous, be taken up by the airway epithelium,  or pass through the
 epithelium to be cleared by the bronchial and pulmonary circulations.  It has
 been suggested that some insoluble particles may penetrate  the mucous and enter
 epithelial cells.25  Conversely, it has been postulated that  particles from
 interstitial spaces and lymphatics may enter the airway lumen and be removed
 subsequently by mucociliary activity.  '27  A recent  review by Wanner emphasizes
 the clinical aspects of mucociliary transport.28  This  review will concentrate
 on the role of mucociliary transport in the normal lung as  a  defense mechanism
 through its clearance of inhaled particles.

      Stationary collimated scintillation detectors can  be used to obtain mea-
 surements of thoracic particle retention which are essentially independent of
 the particle distribution within the thorax.8'19 Figure 7 shows particle reten-
 tion curves for inert, insoluble tagged monodisperse  particles in the hours
 following a 1 minute inhalation exposure for four different nonsmoking, healthy
 human males.   It can be seen that clearance rates vary  widely, even  when the
 amounts cleared are comparable.   On the other hand, clearance rates  are quite
 reproducible in a given individual when the same particle size is inhaled, and
 they vary systematically with changes in particle size  and  the concomitant
 changes in deposition pattern (Figure 8).

      It is clear that there is a wide variation in the  rate at which seemingly
 healthy individuals clear deposited radioaerosols from  the  lungs.  In persons
with chronic  obstructive pulmonary disease, there is  a  somewhat wider varia-
 tion.   However,  the within-subject variation is greatly increased.29 This
 suggests  that  loss of control of mucociliary transport  could  cause and/or
 result  from chronic obstructive  lung disease.

 FACTORS AFFECTING  MUCOCILIARY TRANSPORT

Cigarette  Smoke

     The studies reporting effects of.smoking on mucociliary  transport have been
very confusing because  of  the  widely varying effects  that tobacco smoke produces.30

                                      296

-------
            100
   SUBJECT i 6
      TEST 162 A
PARTICLE SIZE < 4.1
          0
39
80A
2.3
1     03
77T  I55T
3.7   3.4
e    e
to
vo
                                                S      6      7
                                                   TIME - HOURS
                   Figure 7.   Retention of ytagged,  monodisperse ferric oxide microspheres as a
                               function of time following a 1-minute inhalation exposure via
                               mouthpiece, for four  healthy nonsmoking males.

-------
                        Subject 65
Test
     0    »   0   *   I
138A 116A 116T 119A 138T 119T
                                                    Size 1.8   1.7   3.3  4.2   5.8  6.0
NJ
VO
00
                                                                                         12 * 1 day
                           Figure 8.  Retention of y-tagged monodisperse ferric oxide
                                      microspheres of various particle sizes for a
                                      single nonsmoking male participating in a series
                                      of inhalation tests.   The fraction of the inhaled
                                      particles cleared by mucociliary clearance varies
                                      systematically with particle size, but the
                                      effective duration of the bronchial clearance
                                      phase is  relatively independent of size.  With
                                      permission from the American Medical Association.

-------
In man, the immediate response to normal smoking has been either an increase
in tracheobronchial clearance, or no effect.31*'2'33  In the donkey, low expo-
sure levels of cigarette smoke accelerated clearance,31* but impairment of
clearance was observed at higher levels.31*  The relative increase in transport
is greater in the small airways.35  This may be due partly to the adrenergic
stimulation caused by tobacco smoke.  Chronic smoking appears to have a more
variable effect on mucociliary transport.  This is due to variation in dosage,
degrees of individuals' susceptibility to tobacco smoke, the diversity of
studies undertaken, and the small number of subjects involved.  Yeates, et
al.,32 have shown that tracheal transport rates were within normal limits in
nine smokers studied.  Although rapid clearance has been observed in some
long-term smokers, impairment of large airway clearances has been suggested
by Albert, et al.,1 Bohning, et al.,*6 Camner, et al.,37 and Lourenco, et al.38
Pavia, et al.,39 and Thomson and Pavia11 were unable to demonstrate any effect
on of long-term smoking on bronchial clearance.  Albert, et al.1 showed that
some heavy cigarette smokers had long overall bronchial clearance times,
which could be interpreted as slow clearance in small airways.  Faster clear-
ance has been observed in smokers studied three months after cessation of
smoking.1*0  Chronic high-level exposure to cigarette smoke has been found to
severly impair bronchial clearance in the donkey,1*1 with recovery almost
complete within a few weeks after cessation of smoking.

Sulfur Oxides

     In vivo exposures to sulfur dioxide at concentrations that have been
measured in ambient air are not likely to affect mucociliary clearance.  At
higher levels, more typical of some occupational exposures, effects have been
observed.  Wolff, et al.,1*2 exposed nine nonsmokers to 5 ppm (13 mg/m3) of
802 for three hours after an albumin aerosol tagged with 99Tc.  The tracheo-
bronchial mucociliary clearance of the tagged aerosol was essentially the
same as in control tests, except for a transient acceleration at one hour
after the start of the S02 exposure.  In further tests by Wolff, et al.,1*3
it was shown that exercise accelerates bronchial clearance, and 5 ppm of 802
during exercise speeds clearance significantly beyond that produced by the
exercise alone.

     High concentrations of S02 can slow bronchial clearance.  In donkeys,
thirty-minute exposures to 802 via nasal catheters produced delayed bronchial
clearance and severe coughing and mucus discharge via the nose when the con-
centration exceeded 300 ppm. ^**  Mean residence times following exposures of
53 to 300 ppm were not significantly different from control levels.  The one
test performed at a lower concentration (27 ppm) produced an acceleration in
bronchial clearance, which would be consistent with the clearance accelera-
tions seen by Wolff et al.,85'98 with 5 ppm exposures.  These results—an
acceleration at low concentrations and a slowing at higher levels of exposure—
are similar to those produced by cigarette smoke.

     Fairchild, et al.1*5 showed that four-hour exposures to high concentrations
of sulfuric acid (15 mg/m3 of 3.2 ym CMD droplets) reduced the rate of ciliary
clearance of a tagged streptococcal aerosol from the lungs and noses of mice.
At concentrations of 1.5 mg/m3 of 0.6 ym CMD droplets, there were no signifi-
cant effects.

                                      299

-------
      Schlesinger, Lippmann, and Albert46   demonstrated that one-hour exposures
 to submicrometer sulfuric acid mist at concentrations in the range of 200  to
 1000 ymg/m3 produced transient slowings of bronchial mucociliary particle
 clearance in three of four donkeys tested.  In addition, two of the four
 animals developed persistently slowed clearance after about six acid aerosol
 exposures.  Similar acid exposures had no effects on regional particle depo-
 sition or respiratory mechanics, and corresponding exposures to ammonium sul-
 fate had no measurable effects.  In subsequent tests, the two animals showing
 only transient responses, and two previously unexposed animals, were exposed
 one hour daily five days per week, to submicrometer sulfuric acid mist at
 100 yg/m3.47  Within the first few weeks of exposure, all four animals devel-
 oped erratic clearance rates, i.e., rates that on specific test days were
 either significantly slower than or significantly faster than those in their
 preexposure period.  However, the degree and the direction of change in rate
 differed to some extent in the different animals.  The two previously unex-
 posed animals developed persistently slowed bronchial clearance during the
 second three months of exposure and during four months of follow-up clearance
 measurements, while the two previously exposed animals adapted to the exposures
 in the sense that their clearance times fell consistently within the normal
 range after the first few weeks of exposure.

      The sustained, progressive slowing of clearance observed in two initially
 healthy and previously unexposed animals is a significant observation, since
 any persistent alteration of normal mucociliary clearance can have important
 pathological implications.

      Short-term inhalation exposures of healthy human volunteers to sulfuric
 acid mist produced consistent results.  Ten healthy nonsmokers inhaled
 0.5 urn (a  = 1.9) HaSOt, at 0 (control), 110, 330, and 980 yg/m3 for one hour
 via nasal mask in random sequence on four separate days.  Respiratory mechani-
 cal function was assessed before and %, 2 and 4 hrs after the HaSOtf exposure.
 A  99Tc tagged FeaOa aerosol (7.5 ym aerodynamic diameter, ag < 1.1) was
 inhaled ~ 10 min before each I^SOi^ exposure, with flow rate = 1.0 L/s, tidal
 volume = 1.0 L and respiratory rate = 15/min.  Thoracic retention of the
 deposited radioactivity was monitored using collimated scintillation detectors.
 A  tracheal probe was used to determine the tracheal mucociliary transport
 rates  (TMTR's)  of local concentrations of activity.   Bronchial mucociliary
 clearance was markedly altered in a dose dependent pattern in six of the
 individuals and in the group as a whole.   Exposures to 110 yg/m3 resulted  in
 a  significant acceleration in mucpciliary clearance (group mean tracheo-
 bronchial clearance half-time (TB^) decreased from 80 to 50 min.)  Exposures
Jx)  980  yg/m3 caused a significant transient slowing of clearance, with the
 TBu increased to 118 min.   In contrast, there were no significant changes  in
 TMTR, or in indices of ventilatory mechanics (^25»  ^aw and distribution of
 ventilation by  N£ washout.)  The four individuals whose clearance times were
not  significantly affected by these I^SO^ exposures had the fastest bronchial
 clearance among the ten,  and they were each given an additional test with  a
 1,000 yg/m3  E^SOtt exposure preceding the  tagged Fe£03 aerosol.   Three of them
 responded with  threefold or greater increases in TB^.   Thus, 9 of 10 subjects
had  substantial changes in bronchial clearance times following
          48
exposures
                                      300

-------
ALVEOLAR CLEARANCE

     Once a material Is deposited on the respiratory epithelium of the alveo-
lated spaces, clearance takes place by means of two general kinds of processes.
These processes can be termed absorptive and nonabsorptive.  Most likely, the
processes occur together or with temporal variations.

     The most widely-accepted nonabsorptive clearance mechanism in the alveolar
region is  phagocytosis by macrophages.1*9  Despite the common acceptance of
phagocytosis and subsequent cell removal as the dominant nonabsorptive clear-
ance mechanism, it has, so far, not been adequately described in quantitative
terms.  For example, there are conflicting data on the effect of particle size
on phagocytic uptake by rabbit alveolar macrophages.  Holma50 found uptake to
decrease with particle size, while Hahn, Newton, and Bryant51 found the oppo-
site.  Holma1s smallest particles were 1.5 ym, while Halm's largest were
2.2 ym.  The results could be consistent if uptake peaked at 2 ym.  More data
are clearly needed to clarify this issue.

     The clearance pathways for phagocytosed particles remain controversial.
It is generally agreed that macrophages ingest particles and transport them
proximally on the bronchial tree to be swallowed.  However, there is consider-
able disagreement on the predominant pathway between the alveoli and the
bronchial tree.  There are proponents for an interstitial route, while others
favor a continuous proximally moving surface film which draws the cells onto
the ciliated surface at the terminal bronchioles.

     A chronic phase of clearance, characterized by the appearance of particles
within macrophages of the connective tissue compartment of the lungs, begins
from one to three weeks after exposure, according to Sorokin and Brain.52
The extent of such sequestering of particles increases slowly in the subsequent
weeks and months.  For several months, a far greater percentage of alveolar
than of connective tissue macrophages store inert particles, but ultimately
whatever remains uncleared from the lungs resides in the connective tissue.
The fate of cytotoxic particles may differ from that of relatively inert
particles.

     The internal redistribution of particles retained within the lung is an
important factor in determining the site of damage.  Redistribution is appar-
ent in the centrilobular accumulation of pigment seen on the cut surfaces of
human sections.53,5^,55  Such a focal accumulation of particles can also
influence their retention and pathogenic potential.

     For low mass concentrations of short fibers that were neutron activated,
Morgan, Evans, and Holmes56 found no significant differences between amphibole
and chrysotile asbestos in in vivo retention in the rat.  Autoradiographs of
lung sections indicated that the initial deposition was uniform right out to
the lung periphery, while over a few months the fibers accumulated in foci
that were mainly subpleural.

     In subsequent experiments, Morgan, Holmes, and Talbot57 administered
radioactive asbestos to rats by inhalation.  After exposure, the  animals were

                                      301

-------
 sacrificed serially and the lungs were subjected to bronchopulmonary lavage.
 Initial washes were made with a balanced salt solution that removed free
 fiber and cells from the conducting airways.  Subsequent washes were made
 with physiological saline, which recovered cells that originally were in the
 alveolar spaces.  The number of cells and the amount of fiber recovered in
 each wash were measured.  About 20 yg of fiber was deposited in the lung and
 appeared to have no significant effect on either the number or size of free
 cells in the lung.  Uptake of fiber by alveolar macrophages was effectively
 complete after 24 hours.  Analysis of the results suggests that fibers much
 longer than the diameter of the alveolar macrophage (about 12 ym) find their
 way into the alveolar wall from where they cannot be recovered by lavage.
 This process is complete within two weeks of exposure.

      Wright and Kuschner58 used short and long asbestos and manmade mineral
 fibers in intratracheal instillation studies in guinea pigs.  With long
 fibers, all of the materials produced lung fibrosis, although the yields varied
 with the materials used.  However, with equal masses of short fibers of equiva-
 lent fiber diameters, none of the materials produced fibrosis.

      Short fibers are less damaging, it appears, because they can be fully
 ingested by macrophages.59  Longer fibers can rupture the macrophage membrane,
 which can result in release of digestive enzymes and/or loss in mobility.60

      Most inhalation studies have been performed with aerosols containing
 both short and long fibers, and it should be noted that responses may be
 related primarily to the initial burden and/or persistence of the longer
 fibers.   For example, Middleton, Beckett, and Davis61 exposed rats to
 U.I.C.C.  (International Union Against Cancer) standard reference samples of
 amosite,  crocidolite, and chrysotile A at concentrations of 1,  5, and 10 yg/m3,
 and sacrificed them serially over the next four months.   They found less
 retention of chrysotile than of the amphiboles, and the clearance of the
 amphiboles appeared to be dose related.

 TRANSLOCATION OF PARTICLES

      Particles that penetrate the alveolar surface can migrate through the
 lymphatic drainage system to pleural, hilar, and tracheal lymph nodes.   How-
 ever,  the migration is very slow.   Ferin62 found negligible accumulation of
 titanium  dioxide in the lymphatics at 25 days.   Sorokin and Brain52 reported
 that  significant buildup of ferric oxide particles in the lymphatics did not
 take  place until nearly a year after the aerosol exposure.   On the other hand,
 Thomas63  reported that the concentration of radioactive particles in the lymph
 nodes  exceeds  the lung concentration at several months after the end of the
 inhalation.  Ferin6**  found that the fraction of lung dust cleared via the
 lymphatics  increased  with total lung burden of dust.

     Materials deposited by inhalation can usually be found in measurable
 quantities  in  other organs.   In most cases,  the presumed pathway is the blood-
 stream following'gradual dissolution in lung fluids and diffusion into  pul-
monary capillaries.  Absorption presumably depends on materials'  being  mainly
 in a monomeric state  or,  to a lesser extent, in polymeric forms of small dimen-
 sions.65   Some in vitro  solubility models66'67 have proven useful in predicting

                                      302

-------
in vivo clearance rates, but at other times provide inconsistent or erroneous
estimates.  Further work is needed to improve these models.

ALVEOLAR CLEARANCE KINETICS

     The clearance of particles deposited in the alveolar region proceeds in
several temporal phases which usually can be described by a series of expon-
entials.  Each presumably corresponds to a different clearance mechanism.
             68
     Casarett   proposed that the earliest alveolar phase, with a half-time
measured of weeks, is generally associated with phagocytic clearance, while a
slower phase, with a half-time in months or years, is generally associated with
solubility.  The ICRP Task Group model17 does not include the initial alveolar
phase.  Casarett attributes the omission to the task group's overreliance on
data from studies in which the phase was absent because of the cytotoxicity
of the dusts used.  Jammet, et al.69 showed that for hematite dust, a clearance
phase with a half-time of 10 to 12 days is normally present in the cat, rat,
and hamster preceding a slower phase with a half-life exceeding 100 days.
The 10-to-12 day phase disappeared when the animals were exposed to sufficient
plutonium,70 silica dust, or carbon dust,71 while the half-time for the slower
phase was relatively unaffected.

     Considering the recognized importance of the alveolar retention of rela-
tively insoluble particles in the pathogenesis of chronic lung disease, it is
somewhat surprising that examination of the literature yields virtually no
useful data on the rates or routes of alveolar particle clearance in man.

     The only experimental studies on human alveolar clearance are those of
Albert and Arnett72  and Morrow, et al.73*71*

     In the Albert and Arnett study, eight normal human males inhaled neutron
activated metallic iron particles.  For three subjects, there was sufficient
residual activity after the completion of the bronchial clearance for continued
measurement of retention.  For a 32-year-old nonsmoking male, and a 27-year-old
male who was a moderate smoker, the postbronchial clearance occurred in two
phases, a fast phase lasting about one month and a much slower terminal phase.
The faster phase was missing in a 38-year old, two-pack-a-day cigarette
smoking male with chronic cough.  While it is not possible to draw firm
conclusions from these limited data, they are consistent with the recent
findings of Cohen, et al.,75 who studied the alveolar clearance rates of mag-
netic particles in nine nonsmokers and three smokers, using an external
magnetometer for the particle retention measurements.  The clearance rates
in all three smokers were much lower than in any of the nine nonsmokers.  Thus,
it appears that the fast alveolar phase can be detected in man and that ciga-
rette smoking may increase dust retention beyond the retention of the smoke
particulates themselves.  Low doses of cigarette smoke have been shown to
inhibit macrophage phagocytosis.76

     The only other experimental human inhalation studies of alveolar clear-
ance under controlled conditions, as noted, are those of Morrow, et al.  In
an initial study,?tf these authors had four normal individuals inhale a 51fMn02
aerosol with a median size of 0.9 ym, a geometric standard deviation of 1.75,

                                     303

-------
 and a concentration of 4 mg/m3.  The aerosol was inhaled for 20 to  30 min  In
 a breathing pattern in which four normal inhalations alternated with a maximal
 inhalation.  Measurements made more than 48 hours after the inhalation showed
 a single clearance phase for all four individuals, with biological  half-times
 that varied only from 62 to 68 days.

      In the additional human studies of Morrow,  et al.,73 using several  dif-
 ferent aerosols, alveolar clearance rates were also reported in terms of a
 single exponential.  The half-times varied with  the composition of  the part-
 icles.  Half times of 65, 62. and 35 days were found for 5l*Mn02, FeaOa labeled
 with 51Cr, and polystyrene 5*Cr respectively.  The half-time for the polysty-
 rene particles may have been relatively short because it was based  on less
 than 14 days of measurements and, therefore, may have been more influenced
 by a rapid initial rate of alveolar clearances than were the half-times  for
 the iron and manganese oxides, which were followed for periods  between 45
 and 120 days.

 ALVEOLAR RETENTION OF MINERAL DUST

      The pneumoconioses are chronic lung diseases with long latent  periods,
 and radiographic changes and/or functional decrements that result from the
 accumulation of respirable dust in the deep lung regions cannot be  detected
 for many years after the exposures that produced them.   Furthermore, the
 latent period for the pneumononioses tends to increase as the exposure level
 decreases.  For example, evidence for disease may appear within 15  years when
 exposure levels are very high, but not for more  than 30 years when  exposure  %
 levels are much lower.

      The long latent period makes it very difficult to establish causal
 relationships between exposure and response, since the exposure conditions
 at the time the disease is diagnosed may bear little relation to those
 present earlier.

 SUMMARY

      Particle deposition efficiencies and patterns within the respiratory
 tract are  highly variable.   They are determined  by the air path dimensions
 and  configurations  in the individual, the pattern and depth of  the  respirations,
 and  the characteristics of the airborne particles.   The bronchial airways  vary
 considerably  in size among normal,  nonsmoking adults;  these variations are
 even greater  among  smokers without  clinical disease symptoms.

      The distribution of the particles'  deposition sites depends strongly  on
 their aerodynamic diameters.   In normal humans,  inhaled nonhygroscopic part-
 icles that deposit  in the head and  ciliated airways of  the lungs by impact ion
 are  concentrated on a small fraction of the surface.   Cigarette smoking  and
bronchitis produce  an increase in bronchial airway deposition.   For non-
hygroscopic aerosols with aerodynamic diameters  between 10 ym and 1 ym,  an
 increasing fraction remains  airborne as  particle size decreases,  and is
exhaled.  Total  respiratory  tract deposition in  normals reaches a minimum  of
about 10-20 percent  for  particles between 0.2 and 1 ym and increases for
particles, smaller than 0.2 ym.   The  major factor determining the probability

                                      304

-------
of deposition of the smaller particles is their transfer from tidal to reserve
air, and they may remain airborne within the reserve and residual air for a
number of breaths before actually depositing.

     The dominant deposition mechanisms are impaction (for particles larger
than 1.5 ym) , sedimentation (about 0.5 to 1.5 ym)  and diffusion (smaller than
0.5 ym) .  Deposition by sedimentation and diffusion produce relatively uniform
surface deposits in small bronchioles, alveolar ducts, and alveolar sacs.
Hygroscopic particles grow rapidly within the warm, moist airways, becoming
dilute aqueous droplets that can be three to five times the diameter of the
inhaled particles.

     For particles soluble in respiratory tract fluid, systematic uptake may
be relatively complete for all deposition patterns, and there may be local
toxic and/or irritant effects.  On the other hand, slowly soluble particles
depositing in the head beyond the anterior nares or on ciliated tracheobronchial
airways will be transported by the surface flow of respiratory-tract fluid to
the glottis and will be swallowed within one day or less.

     Mucociliary transport rates are highly variable, both along the ciliated
airways of a given individual and between individuals, depending on the thick-
ness and character of the secretions and the number and beat rate of the cilia.
Effective fluid movement depends on the coupling of the ciliary motion within
the sol layer with the more viscous overlying layer.  A moderate increase in
secretions, such as those produced by a few cigarettes or therapeutic dosages
of some adrenergic drugs, can result in acceleration of mucus transport.
Larger dosages or long-term exposures, which can cause an increase in the
number and/or size of the secretory cells and glands, can produce mucus layers
too thick to be propelled effectively by the cilia, and clearance stasis and
periodic retrograde flow can result.

     Mucociliary transport rates decrease distally within the bronchial tree.
The total duration of bronchial clearance in normal humans varies from about
2.5 to 20 hours.  The changes in clearance rates produced by drugs, cigarette
smoke, and various occupational dust exposures, can increase or decrease
these rates by large factors, sometimes by an order of magnitude.  However, the
importance of alterations of mucociliary transport in the pathogenesis of
chronic lung disease is not yet clear.

     Particles deposited in nonciliated airways have large surface-to-volume
ratios, and therefore, significant clearance by dissolution can occur for
materials generally considered insoluble.  They can also be cleared as free
particles, either by passive transport along surface liquids or, after phago-
cytosis, by transport within alveolar macrophages.  If the particles penetrate
the epithelium, either bare or within macrophages, they can be sequestered with-
in cells or enter the lymphatic circulation and be transported to pleural,
hilar, and more distant lymph nodes.  In most cases, the quantitative aspects
of these clearance pathways vary with the composition of the particles and are
poorly understood.  Nontoxic, insoluble particles are cleared from the alveolar
region in a series of temporal phases.  The earliest, lasting several weeks,
appears to involve the clearance of phagocytosized particles via a bronchial
tree.  The terminal phases appear to be related to solubility at interstitial

                                      305

-------
 sites.  The effects of Infectious diseases,  cigarette smoking, and other
 environmental factors on the kinetics of alveolar clearance  are not known
 adequately.

 REFERENCES

 1.   Albert, R. E.,  Lippmann, M.,  and Briscoe, W.,  The Characteristics of
     Bronchial Clearance in Humans and the Effects  of  Cigarette Smoking.
     Arch.  Environ.  Health 18:738-755, 1969.

 2.   Timbrell, V., Inhalation and  Biological  Effects of Asbestos, pp. 429-441.
     In T.  T. Mercer, P. E. Morrow, and W. Stober,  Eds.  Assessment of Air-
     borne Particles.  Fundamentals, Applications,  and Implications to Inhalation
     Toxicity.  A Proceedings Publication of  the Third Rochester International
     Conference on Environmental Toxicity. Springfield:  C.  Thomas, 1972.

 3.   Davis, C. N., The Deposition  of Aerosol  in the Human Lung, pp. 90-99.  In
     V. Bohlau, Ed.  Aerosole in Physik, Medizin und Technik.  Proceedings of
     a conference held in Bad Soden, October  17-18, 1973.  Bad Soden, West
     Germany:  Gesellschaft fur Aerosolforschung,  1973.

 4.   Matsuba, K., and Thurlbeck, W. M., The Number  and Dimensions of Small Air-
     ways in Nonemphysematous Lungs.  Amer. Rev. Resp.  Dis. 104:516-524, 1971.

 5.   Lapp,  N. L., Hankinson, J. L., Amandus,  H., and Palmes,  E. D., Variability
     in the Size of  Airspaces in Normal Human Lungs as  Estimated by Aerosols.
     Thorax 30:293-2999, 1975.

 6.   Dalhamn, T., Mucous Flow and  Ciliary Activity  in  the Trachea of Healthy
     Cats and Rats Exposed to Respiratory Irritant  Gases (S02H3N, HCHO):  A
     Functional and  Morphologic (light microscopic  and  electron microscopic)
     Study, with Special Reference to Technique.  Acta  Physiol.  Scand. 36:
     Suppl.  123, 9-161,  1956.

 7.   Luchtel, D.  L.,  Ultrastructural Observations on the Mucous Layer in Pulmonary
     Airways.   J.  Cell Bio.  70:350a,  1976.

 8.   Lippmann,  M., Albert,  R. E.,  and Peterson, H. T.,  Jr., The Regional
     Deposition of Inhaled  Aerosols in Man, pp. 105-120.  In. W. H. Walton,
     Ed.  Inhaled Particles  III, Vol.  I.   Proceedings of an International
     Symposium Organized by the British  Occupational Hygiene Society in London,
     14-23 September,  1970.  Old Woking,  Surrey:  Unwin Brothers, Ltd., 1971.

9.  Sanchis, J., Dolovich, M., Chalmers, R., and Newhouse, M., Regional
    Distribution and  Lung  Clearance Mechanisms in Smokers and Non-Smokers, pp.
    183-191.   In W. H. Walton, Ed.  Inhaled Particles III, Vol I.  Proceedings
    of an International  Symposium Organized by the British Occupational Hygiene
    Society  in London,  14-23 September  1970.  Old Woking, Surrey:   Unwin
    Brothers Ltd., 1971.
                                     306

-------
10.  Palmes, E. D., and Lippmann, M.,  Influence of Respiratory Air Space
     Dimensions on Aerosol Deposition,  pp.  127-136.   In. W. H. Walton,  Ed.
     Inhaled Particles IV.  Proceedings of  an International Symposium
     Organized by the British Occupational  Hygiene Society in Edinburgh,  22-26
     September 1975.  London:  Pergamon Press ltd.,  1977.

11.  Thomson, M. L., and Pavis, D.,  Long-Term Tobacco Smoking and Mucociliary
     Clearance from the Human Lung in Health and Respiratory  Impairment.  Arch.
     Environ. Health 26:86-89, 1973.

12.  Cohen, V. R., The Effects of Glyceryl  Guaiacolate on  Bronchial Clearance
     in Patients with Chronic Bronchitis.   M. S.  Thesis.   New York University,
     1977.

13.  Davis, C. N., Deposition and Retention of Dust  in the Human  Respiratory
     Tract.  Ann. Occup. Hyg. 7:169-183, 1964.

14.  Hatch, T. F., and Gross, P., Pulmonary Deposition and Retention of In-
     haled Aerosols.  New York:  Academic Press,  1964.  192 pp.

15.  Lippmann, M., Regional Deposition  of Particles  in the Human  Respiratory
     Tract, pp. 213-232.  In D. H. K. Lee,  H. L.  Falk,  and S.  D.  Murphy,  Eds.
     Handbook of Physiology, Section 9:  Reactions to Environmental Agents.
     Bethesda, MD:  The American Physiological Society, 1977-

16.  Stuart, B. 0.,  Deposition of Inhaled Aerosols.   Arch. Int. Med.  131-60-73,
     1973.

17.  Task Group on Lung Dynamics (Committee II-ICRP),  Deposition  and Retention
     Models for Internal Dosimetry of the Human Respiratory Tract.   Health
     Phys.  12:173-207, 1966.

18,  Chan, T. L., and Lippmann, M.,  Experimental Measurements and Empirical
     Modeling of the Regional Deposition of Inhaled Particles in Humans.
     Amer. Ind. Hyg. Assoc. J. 41:399-409,  1980.

19.  Stahlhofen, W., Gebhart, J., and Heyder, J., Experimental Determination
     of the Regional Deposition of Aerosol  Particles in the Human Respiratory
     Tract.  Amer. Ind. Hyg. Assoc.  J.  41:385-398, 1980.

20.  Swift, D. L., Shanty, F., and O'Neil,  J. T., Human Respiratory Deposition
     Patterns of Fume-like Particles.   Presented in Part at  the 1977 Amer.
     Ind. Hyg. Conf., New Orleans, La., May 26, 1977.

21.  Lippmann, M., and Albert, R. E.,  The  Effect of Particle Size on the
     Regional Deposition of Inhaled Aerosols in the Human Respiratory Tract.
     Amer. Ind. Hyg. Assoc. J. 30-257-275,  1969.

22.  Lippmann, M., and Altshuler, B.,  Regional Deposition of Aerosols, pp.
     25-48.  In. E. F. Aharonson, A. Ben-David, and M. A.  Klingberg, Eds.
     Air Pollution and the Lung.  Proceedings of the Twentieth Annual
                                     307

-------
      "OHOLO" Biological Conference,  Maalot,  Israel, March  16-19, 1975.
      New York:  John Wiley & Sons,  Inc.  1976.

 23.   Schlesinger, R. B., and Lippmann, M., Particle Deposition in Casts of
      the Human Upper Tracheobronchial Tree.  Amer. Ind. Hyg. Assoc. J. 33:
      327-251, 1972.

 24.   Schlesinger, R. B., and M.  Lippmann.  Selective Particle Deposition and
      Bronchogenic Carcinoma.  Environ. Res.  15:424-431, 1978.

 25.   Brain, J. D., Godleski, J.  J.,  and  Sorokin,  S. P., Quantification, Origin,
      and Fate of Pulmonary Macrophages,  pp.  849-892.  In:  J. D. Brain, D. F.
      Proctor, and L. M. Reid, Eds.   Respiratory Defense Mechanisms - Part II,
      New York, Marcel Dekker, 1977.

 26.   Brundelet, P. J., Experimental  Study of the  Dust Clearance Mechanism of
      the Lung.  I. Histoldgical  Study in Rate of  the Intra-pulmonary Bronchial
      Route of Elimination.   Acta Pathol.  Microbiol.  Scan. Suppl. 175:1-141,
      1965.

 27.   Tucker, A. D., Wyatt,  J. H., and Undery, D., Clearance of Inhaled Part-
      icles from Alveoli by Normal Interstitial Drainage Pathways.  J. Appl.
      Physiol. 35:719-732,  1973.

 28.   Wanner, A., Clinical  Aspects of Mucociliary  Transport.  Amer. Rev. Resp.
      Dis.  116:73-125,  1977.

 29.   Yeates, D. B., Pitts,  B. R., Spektor, D., Karron, G. A., and Albert, R.
      E.,  Tracheal Mucociliary Transport  and  its Relationship to Bronchial
      Clearance in Man.   Amer. Rev. Resp. Dis. 117 (4:2)2679, 1978.

 30.   Asmundsson, T.,  and Kilburn, K.  H., Mechanisms of Respiratory Tract
      Clearance,  pp.  107-180.   In M.  J. Dulfano, Ed. Sputum.  Fundamentals
      and  Clinical Pathology.   Springfield:   C. Thomas, 1973.

 31.   Albert,  R.  E.,  Lippmann, M., Peterson,  H. T., Jr., Berger, J., Sanborn,
      K.,  and Bohning, D., Bronchial Deposition and Clearance of.. Aerosols.
     Arch.   Intern. Med.  131:115-127, 1973.

 32.  Yeates,  D.  B., Asp in, N., Levison, H.,  Jones, M. T., and Bryan, A. C.,
     Mucociliary Tracheal Transport Rates in Man.  J. Appl. Physiol, 39:487-
      495,  1975.

 33.  Camner,  P.,  Philipson, K.,  and Arvidsson, T., Cigarette Smoking in Man.
     Short-term  Effect on Mucociliary Transport.  Arch. Environ. Health 23:421-
     426, 1971.

34.  Albert, R.  E., Berger, J., Sanborn,  K., and Lippmann,  M., Effects of
     Cigarette Smoke Components on Bronchial Clearance in the Donkey.  Arch.
    »Environ.  Health 29:99-106,  1974.
                                     308

-------
35.  Albert, R. E., H. T. Peterson, Jr., D.  E.  Bohning, and M.  Lippmann.
     Short-term effects of cigarette smoking on bronchial clearance in humans.
     Arch. Environ. Health 30:361-367, 1975.

36.  Bohning, D. E., R. E. Albert, M. Lippmann, and W.  M. Foster.   Tracheobron-
     chial particle deposition and clearance.   A study of the effects of
     cigarette smoking in monozygotic twins. Arch Environ Health 30:457-
     462, 1975.

37.  Camner, P., and K. Philipson.  Tracheobronchial clearance in smoking-
     discordant twins.  Arch Environ Health 25:60-63, 1972.

38.  Lourenco, R. V., M. F. Klimek, and C.  J. Borowski.  Deposition and
     clearance of 2 y particles in the tracheobronchial tree of normal
     subjects—smokers and nonsmokers.  J Clin  Invest 50:1411-1419, 1971.

39.  Pavia, D., M. D. Short, and M. L. Thomson.  No demonstrable long term
     effects of cigarette smoking on the mucociliary mechanism of the human
     lung.  Nature 226:1228-1231, 1970.

40.  Camner, P., K. Philipson, and T. Arvidsson.  Withdrawal of cigarette
     smoking.  A study of tracheobronchial clearance.  Arch Environ Health.
     16:90-92, 1973.

41.  Albert, R. E., D. Alessandro, M. Lippmann, and J. Berger.  Long-term
     smoking in the donkey:  Effect on tracheobronchial particle clearance.
     Arch Environ Health 22:12-19, 1971.

42.  Wolff, R. K., M. Dolovich, C. Rossman, and H. T. Newhouse.  Sulfur
     dioxide and tracheobronchial clearance in  man.  Arch Environ Health
     30:521-527, 1975.

43.  Wolff, R. K., M. Dolovich, 6. Obminski, and M. T. Newhouse.  Effect of
     sulphur dioxide on tracheobronchial clearance at rest and during exer-
     cise, pp. 321-330.  In W. H. Walton, Ed.,  Inhaled Particles IV.  Pro-
     ceedings of an International Symposium organized by the British Occu-
     pational Hygiene Society in Edinburgh, 22-26 September 1975.  Oxford,
     Pergamon, 1977.

44.  Spiegelman, J. R., G. D. Hanson, A. Lazarus, R. J. Bennett, M. Lippman,
     and R. E. Albert.  Effect of acute sulfur  dioxide exposure on bronchial
     clearance in the donkey.  Arch Environ Health 17:321-326, 1968.

45.  Fairchild, G. A., P. Kane, B. Adams, and D. Coffin.  Sulfuric acid and
     streptococci clearance from respiratory tracts of mice.  Arch Environ
     Health 30:538-545, 1975.

46.  Schlesinger, R. B., M. Lippmann, and R. E. Albert.  Effects of short-
     term exposures to sulfuric acid and ammonium sulfate aerosols upon
     bronchial airway function in the donkey.  Amer  Ind Hyg Assoc J.
     39:275-286, 1978.
                                      309

-------
 47.   Schlesinger,  R.  B.,  M.  Halpern,  R.  E. Albert, and M. Lippmann.  Effect of
      chronic inhalation of sulfuric acid mist  upon mucociliary clearance from
      the lungs of  donkeys.   J Environ Path and Tox.   2:1351-1367, 1979.

 48.   Leikauf,  G. D.,  D. B.  Yeates,  D.  M. Spektor, and M. Lippmann.  Effect of
      sulfuric  acid aerosol on bronchial  mucociliary clearance.  Amer Rev
      Dis.   121:245a,  1980.

 49.   Brain, J. D.   Free cells in the  lungs.  Some aspects of their role,
      quantitation, and regulation.  Arch Intern Med.  126:477-487, 1970.

 50.   Holma, B.  Short-term lung clearance in rabbits  exposed to a radioactive
      bi-disperse (6 and 3 ym) polystyrene aerosol, pp. 189-201.  In C. N.
      Davies, Ed.,  Inhaled Particles and  Vapours II.   Proceedings of an
      International Symposium organized by the  British Occupational Hygiene
      Society in Cambridge,  28 September  - 1  October 1965.  London, Pergamon,
      1966.

 51.   Hahn,  F.  F.,  G.  T. Newton, and P. L. Bryant.  In vitro phagocytosis of
      respirable-sized monodisperse  particles by alveolar macrophages,
      pp.  424-435.   In C.  L.  Sanders,  Ed., Pulmonary Macrophages and Epithelial
      Cells.  Conf-760927 NTIS, Springfield,  Va., 1977.

 52.   Sorokin,  S. P.,  and J.  D. Brain.  Pathways of clearance in mouse lungs
      exposed to iron oxide aerosols.   Anat Record.  .181:581-625, 1975.

 53.   Pratt, P.C.,  and K.  H.  Kilburn.   Extent of pulmonary pigmentation as an
      indicator of  particulate environmental  air pollution, pp. 661-669.
      In  W.  H.  Walton, Ed.,  Inhaled  Particles III, Part II.  Proceedings
      on  an  International Symposium  organized by the British Occupational
      Hygiene Society  in London, 14-23 September, 1970.  Old Woking, Surrey,
      Unwin  Bros. 1971.

 54.   Simson, F. W.  Reconstruction  models showing the moderately early simple
      silicotic process and  how it affects definite parts of the primary unit
      of  the lung.  J  Pathol  Bacteriol.  40:37-44, 1935.

 55.   Heppleston, A. G.  Pathological  anatomy of simple pneumoconiosis in coal
      workers.   J Pathol Bacteriol.  66:235-246, 1953.

 56.   Morgan, A., J. C.  Evans and A. Holmes.  Deposition and clearance of
      inhaled fibrous  minerals in the  rat.  Studies using radioactive tracer
      techniques, pp.  259-274.   In W.  H.  Walton, Ed.,  Inhaled Particles IV.
      Proceedings of an  International  Symposium organized by the British
      Occupational Hygiene Society in  Edinburgh, 22-26 September 1975.
      Oxford, Pergamon,  1977.

57.  Morgan, A., A. Holmes,  and R.  T.  Talbot.   The fate of inhaled asbestos
      fibers deposited in  the rat lung:  A quantitative approach, pp. 436-450
      in C. L.  Sanders,  Ed.,  Pulmonary Macrophage and  Epithelial Cells,
     CONF-760027, NTIS, Springfield,  Va., 1977.


                                       310

-------
58.   Wright, G. W. ,  and Kuschner, M. , The influence of varying lengths of
      glass and asbestos fibers on tissue response in guinea pigs, pp. 455-
      474.  In W. H.  Walton, Ed., Inhaled Particles IV.  Proceedings of an
      International Symposium organized by the British Occupational Hygiene
      Society in Edinburgh, 22-26 September 1975.   Oxford, Pergamon, 1977.

59.   Beck, F. G. , Bruch, J., Friedrichs, K. H. , Hilscher, W. , and Pott, F. ,
      Fibrous silicates in animal experiments and cell-culture in morpho-
      logical cell and tissue reactions according to different physical
      chemical influences, pp. 477-486.  In W. H.  Walton, Ed. Inhaled Parti-
      cles III.  Proceedings of an International Symposium organized by the
      British Occupational Hygiene Society in London, 14-23 September, 1970.
      Old Woking, Surrey, Unwin Bros., 1971.

60.   Allison, A. C., Mechanisms of macrophage damage in relation to the
      pathogenesis of some lung diseases, pp. 1075-1102.  In J. D. Brain,
      D. F. Proctor,  and L. M. Reid, Eds.  Respiratory Defense Mechanisms -
      Part II, New York, Marcel Dekker, 1977.

61.   Middleton* A. P., Beckett, S. T., and Davis, J. M. G., A study of the
      short-term retention and clearance of inhaled asbestos in rats, using
      U.I.C.C. standard reference samples, pp. 247-258.  In W. H. Walton,
      Ed., Inhaled Particles IV.  Proceedings of an International Symposium
      organized by the British Occupational Hygiene Society in Edinburgh,
      22-26 September 1975.  Oxford, Pergamon, 1977.

62.   Ferin, J. , Lung clearance of particles, pp.  64-78.  In E. F. Aharonson,
      A. Ben-David, and M. A. Klingberg, Eds. Air Pollution and the Lung.
      Proceedings of the Twentieth Annual "OHOLO" Biological Conference,
      Maalot, Israel, March 16-19, 1975.  New York:  John Wiley & Sons,
      Inc., 1976.

63.   Thomas, R. G. ,  An interspecies model for retention of inhaled particles.
      pp. 405-418.  In T. T. Mercer, P. E. Morrow, and W. Stober, Eds.  Assess-
      ment of Airborne Particles.  Springfield, I11J, C. C. Thomas, 1972.
64.   Ferin, J.., Effect of particle content of lung on clearance pathways,
      pp. 414-528.  In C. L. Sanders, Ed., Pulmonary Macrophages and
      Epithelial Cells.  Conf-760927 NTIS, Springfield, VA.  1977.

65.   Morrow, P. E., Alveolar clearance of aerosols.  Arch. Int. Med.
      131:101-108, 1973.

66.   Morrow, P. E., Gibb, F. R., Davies, H., and Fisher, M. , Dust removal
      from the lung parenchyma:  An investigation of clearance simulants.
      Toxicol. Appl. Pharmacol.  12:372-396, 1968.

67.   Mercer, T. T. , On the role of particle size in the dissolution of
      lung burdens.  Health Phys. 13:1211-1221, 1967.
                                      311

-------
 68.    Casarett,  L.  J.,  The vital  sacs:  Alvelar  clearance mechanisms in
       inhalation toxicology,  pp.  2-36.  In W.  J. Hayes, Jr., Ed. Essays
       in Toxicology,  Volume 3.  New York:   Academic press, 1972.

 69.   Jammet,  H., J. Lafuma, J.  C.  Nenot, M. Chameaud, M. Perreau, M. LeBouffant,
      M.  Lefevre, and  M.  Martin.   Lung clearance:  Silicosis and anthracosis,
      pp.  435-437.   In H. A. Shapiro.  Ed.  Pneumoconiosis.  Proceedings of the
      International  Conference,  Johannesburg, 1969.  Capetown:  Oxford Univer-
      sity Press, 1970.

 70.   Nenot, J.  C.   Etude de 1'irradiation  sur  1'epuration pulmonaire, pp. 239-
      246.   In W. H. Walton, Ed.,  Inhaled Particles III, Vol. I.  Proceedings
      of  an International Symposium organized by  the British Occupational
      Hygiene  Society  in London, 14-23 September  1970.  Old Woking, Surrey:
      Unwin Bros., Ltd.,  1971.

 71.   Le  Bouffant, L.  Influence de la nature des poussieres et de la charge-
      pulmonair  sur  1'epuration, pp.  227-237.   In W. H. Walton, Ed. Inhaled
      Particles  III, Vol. I.  Proceedings of an International Symposium
      organized  by the British Occupational Hygiene Society in London, 14-23
      September  1970.  Old Woking,  Surrey:   Unwin Bros., Ltd., 1971.

 72.   Albert,  R.  E.  and  L.  C.  Arnett.  Clearance  of radioactive dust from the
      lung.  Arch Ind  Health.  12:99-106, 1955.

 73.   Morrow,  P.  E., F.  R.  Gibb, and K. Gazioglu.  A study of particulate
      clearance  from the human lungs.  Amer Rev Resp. Dis.  96:1209-1221,
      1967.

 74.   Morrow,  P.  E., F.  R.  Gibb, and K. Gazioglu.  The clearance of dust from
      the lower  respiratory tract  of man.   An experimental study, pp. 351-358.
      In C. N. Davies, Ed.  Inhaled  Particles and  Vapours II.  Proceedings of
      an International Symposium organized  by the British Occupational Hygiene
      Society, Cambridge, 28 September to 1 October 1965.  Oxford:  Pergamon
      Press, 1967.

75.   Cohen, D.,  S. F. Arai, and J.  D. Brain.   Smoking impairs long term dust
      clearance from the  lung.  Science.  204:514-516, 4 May 1979.

76.  Haroz, R. K. and L. Mattenberger-Kreber.  Effect of cigarette smoke on
     macrophage  phagocytosis, pp.  36-57.   In C.  L. Sanders, Ed., Pulmonary
     Macrophages and Epithelial Cells.  CONF-760927, NTIS, Springfield, VA.
     1977.
                                      312

-------
                         FATE OF INGESTED PARTICULATES

                                      by

                    Dr.  James Millette and Mr. M. Rosenthal*
               Exposure Evaluation Branch, Epidemiology Division
                      Health Effects Research Laboratory
                     U.S. Environmental Protection  Agency
                               Cincinnati, Ohio
                                    ABSTRACT

    People consume many solid particles everyday through food, water, and beverages.
    A review of the literature shows that while there is no mass penetration of
    particles through the walls of the gastrointestinal tract, there  is consider-
    able evidence that mineral fibers and other durable particulates  do transmigrate
    from the G.I. tract to  other parts of the body.  Several mechanisms for parti-
    culate penetration have been, postulated and the mechanism may well be different
    for different types of  materials and for different sizes of particles.  Pene-
    tration of asbestos fibers is a relatively rare occurrence and is estimated
    to be on the order of 1 fiber in 10,000.  Once in the body, some  fibers and
    other particulates may  be accumulated in certain tissues but many are cleared
    and eliminated through  the urinary tract.
     Particulates form a general category which is not very well defined.   In
the drinking water industry we loosely classify the particulate component  as
pieces of material of varying composition ranging up to 100 micrometers  in
size.  The  finding of particles larger than 100 micrometers (0.1 millimeter)
in publicly supplied drinking water usually brings vigorous complaints from
the consumer.   The question of the lower limit  of the size of particulates
has largely been ignored.  In the present analytical techniques available  for
water, particles smaller than 0.1 micrometer are not considered.  The question
of what constitutes a particulate in food is far more difficult than when
considering water.  Analyzing food for particulates is an extremely  difficult
task.

     If particulates swallowed with food, beverages, and water do not migrate
across the  gastrointestinal mucosa of the alimentary canal, the question of
whether any Ingested particle could be a cancer risk would be greatly simpli-
fied.  It is clear that the food and liquids one consumes everyday contain a
high number of  solid particles and by far the bulk of the nondigested material
moves through the digestive system as illustrated in Figure 1 and is discharged
*Presented by Dr. James Millette.    313

-------
          I MOUTHI
   [PHARYNX (6 INCHES)!
  IESOPHAGUS (9 INCHES)!
          STOMACH
    [DUODENUM  (1 FOOT)!
          [JEJUNUM]
           IILEUMI
[LARGE  INTESTINE (5 FEET)j
            RNUSI
SMALL  INTESTINE (20 FEET
   Figure 1.   Pathway of ingested .material not assimilated
             by the gastrointestinal tract.

                           314

-------
in the feces.  While enroute on a normal trip, which may take a number of
hours, some particles are coated with secretions, subjected to gastric juices,
digestive enzymes, and drastic pH changes from pH2 to pH8.  Only particles
with certain sustaining traits can be considered candidates for direct trans-
port through the GI wall.  A more complete discussion of the activities of the
digestive tract can be found in the appendix of this article.

     Since asbestos and other durable fibrous materials placed directly in
the peritoneum of animals have resulted in malignant neoplasms, the questions
of which materials and how much can pass through the walls of gastrointestinal
tract are particularly important.

     The results of three laboratories' investigations on asbestos fiber pene-
tration were described in one publication in 1974.1  The paper reported no
evidence of penetration of the G.I. mucosa by mineral fibers.  Although a
review of the studies shows "their results to be suggestive, the studies them-
selves were not adequately designed to answer the full question of penetration.
In the first laboratory, three studies were performed.  The first investigation
consisted of ten rats fed laboratory chow containing 5 percent ball--milled
chrysotile for 21 months.  After nine years storage in formaldehyde, tissue
of the G.I. tract was prepared for electron microscopy.  The digests of the
tissues of the G.I. tract contained chrysotile fibers but it was impossible to
tell whether the fibers had been in the mucosa or were a result of contamina-
tion.  Unfortunately at the time the tissues had been preserved, tissue from
the G.I. tract was not isolated from other tissues and no attempt was made to
keep the formaldehyde solution that had been contaminated with asbestos con-
taining fecal material from contaminating the other tissues with asbestos
fibers.  Fibers were found in the digests of the mesenteric tissue from both
test and control animals but because the experimental procedure used unfiltered
water and contaminated reagents, the findings could not be interpreted.  No
fibers were found in sections of intestines examined with electron microscopy
but the amount of tissue searched was not given in the experimental details.

     In a second study, still in the first laboratory, 20 unanaesthetized rats
were given 400 mg of amosite or taconite mine tailings in 1 ml of suspension
by gavage.  Fibers were found in the digest of G.I. tract tissues in some but
not all of the rats given amosite.  No data were given as to the amount of
tissue analyzed.

     A third study incorporated finely ground amosite or taconite tailings
into oleomargarine to obtain 10 percent amosite content or 20 percent taconite
content.  Fibers were found in the mesentery, lung, or kidney digests of some
of the animals exposed to amosite or taconite but not in the digests of the
control rat tissues.  No data were given as to the actual amount of tissue
examined so it is impossible to estimate the significance of finding fibers.

     In the second laboratory studies reported in the 1974 article, the gut
and other tissues of rats fed 0.2-0.4 percent crocidolite asbestos in butter
for varying periods of time were examined only with optical microscopy.  No
evidence of fiber penetration was found.  No data on the magnification used
or amount of tissue surveyed were given.
                                     315

-------
      Only partial data from the third laboratory was available  for  inclusion
 into the report.  Chrysotile and crocidolite "properly ground"  were mixed
 with butter to a 0.5 percent level by weight.  Light microscopic  examination
 of tissue sections showed no asbestos fibers that had penetrated.   Electron
 microscopic examination of sections of small intestine and mesenteric  lymph
 nodes also showed no signs of penetration.   Again, no data were given  as to
 the actual amount of tissue examined.

      Together the results of the three laboratories suggest  that  there is no
 mass penetration of fibers through the gut  wall, but because of the contamina-
 tion of the first laboratory and lack of sensitivity in the  second  and third
 laboratories, the results in this 1974 article are not confirming evidence
 that durable fibers cannot transmigrate from the gastrointestinal tissues to
 the body.

      A number of other investigators have addressed the question  of digestive
 tract penetration by particulates.  A number of their findings  support the
 contention that particulate penetration is  not a large scale event  but does
 occur.

      One of the first reports on the subject showed electron micrographs of
 asbestos fibers in many sites of the colonic epithelium and  lamina  propria
 of rats fed a 6 percent asbestos diet for 3 months.2  Asbestos  particles
 found in the tissue were up to 1 micrometer in length.   No data were given
 on the size of the asbestos before feeding  or the amount of  tissue  analyzed.
 The authors postulated that the particles had migrated through  the  mucous of
 the goblet cells into the cell itself and hence into the lamina propria.

      In a human study, amphibole fibers were found in significant numbers in
 the lung, liver, and jejunum in 29 of 39 Duluth, Minnesota residents with
 oral exposure to mineral fibers in their drinking water lasting up  to  15
 years.8  Among 21 control residents of St.  Paul, MN and Houston,  TX only two
 subjects were found to contain the amphibole type fiber,  in  each  instance a
 single fiber from a single tissue site.

      The methods of penetration of the digestive tract are postulated  to be
 direct piercing of the cells by long fibers and pinocytosis  of  short fibers.
 According to Volkheimer,^ particles in the  nanometer size range can be
 channeled through the intestinal absorptive cell (enterocyte) by  a  pinocytosis-
 like process in minute bubbles with a diameter of up to 50 ran.  Larger
 particles,  whose diameter is well within the micrometer range,  are  suggested
 to be regularly incorporated by persorption.   In this  process particles are
 "kneaded" into  the mucosa during their passage through the digestive tract.
 Volkheimer  suggests that the particles pass between the epithelial  cells into
 the  subepithelial layer.   It is easy to conclude that when durable  fibrous
materials are kneaded into the tissue some  of the fibers  would  directly
 pierce  the  cells.   Asbestos is known to be  taken in by  cultured cells.

     Gross  et.  al.,1  raised an important point in the  question  of penetration
 of the digestive  tract  by solid particles.   If penetration of the GI mucosa
by- particulates did occur,  the amount of stored material  in  the intestinal


                                     316

-------
submucosa and In mesenterlc lymph nodes would increase with age.   Recent data
suggest that many of the particles which have penetrated may be cleared from
the body via the urinary tract.  Amphibole fibers were found in the urine of
persons who had been drinking unfiltered water containing the mineral.
Asbestos fibers have also been found in the urine of a baboon forced to ingest
the material.11  In most individuals a balance between fibers taken in and
those cleared may be reached over time.  Fiber concentration in tissue may in-
crease with age but at a slower rate than fiber penetration of the digestive
tract.

     Nonasbestos materials also penetrate the digestive tract.  In their mini-
review of intestinal absorption of particulate matter, Le Fevre and Joel list
a number of materials which have been reported to pass the intestinal barrier.12
These include colloidal metals, latex spheres, polyvinyl chloride pellets, and
iron filings.  Volkheimer9 reports using starch granules, cellulose particles,
powdered rabbit hairs, charcoal, pollen and silicate crystals in his persorp-
tion studies.  Cook reported finding nonfibrous particles of silica, diatom
fragments, fibers of iron, titanium and glass of probable man-made origin.
Attapulgite clay fibers have been reported in the urine of a person ingesting
large doses for medical purposes.*3

     Little data were available on the rate of transfer of various solid
materials through the digestive tract.  Estimates of the passage rate for
asbestiform fibers range from 1 fiber in 1,00010 to 1 fiber in 10,000.^
From the data provided by Cook and Olson10 for 4 subjects ingesting unfiltered
Lake Superior water over a number of years, the average concentration of fibers
in the urine was 0.66 x 106 per liter.  Compared with the average fiber content
of Lake Superior water of about 100 million fibers per liter, this fact suggests
that as many as 1 in 200 fibers crosses the digestive tract.  This estimate
assumes that a steady state between the number of ingested fibers and the number
of fibers eliminated in the urine could occur so that the number of fibers in
urine would represent the minimum number of fibers passing through the intestinal
mucosa.  As indicated by Cook and Olson, even the ratio of 1 in 1000 fibers
passing seems remarkably large and may be modified by further measure.

     The value of 1 fiber penetrating in 100,000 was determined using a rat
study in which an asbestos pellet weighing approximately 20 mg was introduced
into the stomach of rats by catheter.    The value of 1 in 100,000 may be an
underestimate of what happens when fibers are ingested in water since the
number of individual fibers available for penetration was dependent on the rats'
ability to break up the pellet internally.  The same researchers have reported
the passage of both chrysotile and crocidolite fibers across the gastrointes-
tinal wall and that the larger chrysotile fibers appear to pass at a higher
rate than short fibers.15

     If there is a balance achieved between intake of fibers and excretion
through the urine, a maximum accumulated level of fibers in some tissues may
be attained.  It is interesting to note that  the highest accumulation of
chrysotile fibers in tissues (other than lung) reported by three independent
researchers were all on the order of 10 million fibers per gram of tissue.
See Table 1.
                                      317

-------
      TABLE 1.   MAXIMUM TISSUE FIBER CONCENTRATIONS  REPORTED FOR CHRYSOTILE

                                    Fibers
             Tissue                 per gram    Chrysotile Exposure

          Rat omentum1*            8.6 x 10s*   1% in diet for 6 weeks

          Human liver8           10.9 x 10s**  Unknown exposure over
                                                 lifetime

          Baboon kidney cortex7   7.8 x 106*   3  x 1013 fibers/kg in
                                                 9 days

       *Corrected for control tissue concentration.

      **Corrected for blank filter concentration.


      In another study, a single suspension of chrysotile asbestos was injected
 into the stomachs of 10 anaesthetized rats.3  Asbestos fibers were found in
 animals sacrificed 2 to 4 days later in the omentum (which surrounds the small
 intestine), blood,  spleen and brain.  The authors postulated that long fibers
 may pierce the gut like a needle, whereas pinocytosis may account for the
 absorption of smaller fibers.  Fibers in one tissue were as long as 15 ym and one
 fiber in the blood was 23 urn long.  Some questions  have been raised about the
 injection technique in that there might have been passage of fibers through
 the needle tract into the abdominal cavity.

      In a second experiment, the same researchers fed 10 rats a diet containing
 1 percent chrysotile asbestos for 6 weeks.4  Tissues were prepared using a
 procedure which included ashing, solubilization  with dilute HC1, filtration,
 ashing the filter and dropping a 5 ul aliquot of tissue suspension on an
 electron microscope grid.  Analysis of the tissues  showed higher levels of
 asbestos in all tissues of test animals examined than in controls with the
 highest levels in the omentum (9.66 x 106 fibers per gram) followed by the
 brain,  lung, liver, blood and kidney.  Fiber lengths were up to 5 um.  The
 authors concluded that ingested asbestos can penetrate the walls of the diges-
 tive tract but that when the amount of asbestos  consumed by the rats in the
 6-week period  is considered, the amount found in tissues represent an extremely
 small portion.

      One hour  after amosite asbestos fibers suspended in saline were placed in
 an  isolated segment of rat jejunum in vivo, the  animal was sacrificed and
 fibers  were found penetrating the epithelial surface.5 Amosite fibers with
 diameters up to 1.4 um and visible lengths up to 30 um were seen in epithelial
 cells  or in the lamina propria.   All fibers seemed  to enter the cell through
 its  luminal surface.   None penetrated the intercellular junctions.  The authors
 concluded that  penetration of the epithelial cells  of the intestine directly
 through their  cell  bodies is at least one of the mechanisms by which asbestos
 fibers  can gain access to the lamina propria of  the Intestine.

     Fiber penetration of the digestive tract has also been documented in pri-
mates. * Chrysotile  asbestos fibers up to 35 um long were found in the kidney

                                       318

-------
cortex of a newborn baboon fed asbestos containing milk formula for 9 days.
Statistically significant higher levels of fibers were found in the kidney
(especially kidney cortex), lymph nodes, spleen, colon, and esophagus over
control tissues.  Five other tissues, stomach, liver, duodenum, cecum, and
heart contained concentration of fibers not different from control tissues.
The tissue was prepared using a procedure of low temperature ashing, solubili-
zation with 1 percent acetic acid, filtration, ashing of the filter and placing
6 ul of tissue suspension on an electron microscope grid.  There were fibers
of various sizes found in the test animal tissues indicating, at least with
the newborn, a range of sizes of asbestos fibers can penetrate.

     This may indicate the upper level for chrysotile accumulation in tissue.
Other particulates may accumulate to different levels and be regulated by
different clearance mechanisms.

     In summary, the research conducted on the penetration of the digestive
tract by solid materials is sufficient to conclude that such penetration is
not on a large scale but can and does occur.  Research findings also suggest
that while some fibers may be entrained in body tissue many are cleared through
the urinary tract.

REFERENCES

1.   Gross, P., R.A. Barley, L.M. Swlnburns, J.M.6. Davis, and W.B. Greene.
     Ingested mineral fibers, do they penetrate tissue or cause cancer.  Arch.
     Envir. Health 29:341-347 (1974).

2.   Westlake, G.E., H.J. Spjut, and M.N. Smith.  Penetration of colonic mucosa
     by asbestos particles.  Lab. Invest. 14(11):2029-2033 (1965).

3.   Pontefractj R.D. and H.M. Cunningham.  Penetration of asbestos through
     the digestive tract of rats.  Nature 243:352-353 (1973).

4.   Cunningham, H.M., C.A. Moodie, G.A. Lawrence, and R.D. Pontefract.
     Chronic effects of ingested asbestos in rats.  Arch. Envir. Contain.
     Toxicol. 6:507-513 (1977).

5.   Storeygard, A.R. and A.L. Brown.  Penetration of the small intestinal
     mucosa by asbestos fibers.  Mayo Clin. Proc. 52:809-812 (1977).

6.   Patel-Mandlik, K.J., W.H. Hallenbeck, and J.R. Millette.  Asbestos fibers:
     (1) a modified preparation of tissue samples for analysis by electron
     microscopy, (2) presence of fibers in tissues of baboon fed chrysotile
     asbestos.  J. of Envir. Path. Toxic.  2:1385-1395 (1975).

7.   Patel-Mandlik, K.J. and J.R. Millette.  Evidence of migration of ingested
     asbestos into various baboon organs.  Scanning Electron Micr./-1980/l,
     347-354 (1980).

8.   Carter, R.E. and W.F. Taylor.  Identification of a particular amphibole
     asbestos fiber in tissues of persons exposed to a high oral intake of
     the mineral.  Envir. Res. 21:85-93  (1980).

                                      319

-------
 9.  Volkheimer, G-., Passage of particles through the wall of the gastrointes-
     tinal tract.  Envir. Health Persp. 9:215-225 (1974).

10.  Cook, P.M. and G.F. Olson.  Ingested mineral fibers:  elimination in
     human urine. Sci. 204:195-198  (1979).

11.  Hallenheck, W.H. and K.J. Patel-Mandlik.  Presence of fibers in the urine
     of a baboon gavaged with chrysotile asbestos.  Environ. Res. 20(2):335-340
     (1979).

12.  LeFevre, M.E. and D.D. Joel.  Minireview:  intestinal absorption of parti-
     culate mater.  Life Sci. 21:1403-1408  (1977).

13.  Bignon, J., P. Sebastien, A. Gaudichet, and M.C. Jaurand.  Biological
     effects of attapulgite.  Symposium on Asbestos, Lyon, France (1979).

14.  Sebastien, P., X. Janson, G. Bonnaud, G. Riba, R. Masse and J. Bignon.
     "Translocation of asbestos fibers through respiratory tract and gastro-
     intestinal tract according to  fiber type and size."  Dusts and Disease,
     R. Lemen and J. Dement (eds),  SOEH, Pathotox Pub., Park Forest South,
     IL. p 78-82 (1979).

15.  Sebastien, P., R. Masse, and J. Bignon.  Recovery of ingested asbestos
     fiber from the gastrointestinal lymph in rats.  Envir. Res. 22(1):201-216
     (1980).
                                      320

-------
                                   APPENDIX

                            THE DIGESTIVE PROCESSES
     Ingested material, whether it is considered food or foreign matter,  must
eventually either pass through the alimentary canal (gastrointestinal tract)
or be assimilated by the body somewhat along the twenty seven or so feet  of
the canal.

     Ingested material enters the 61 tract through the mouth (and sometimes
through the nasal cavity due to swallowing of material cleared from the res-
piratory tract).  In the mouth, ingested material is acted upon by secretions
from the Parotid, Submaxillary and Sublingual Salivary Glands.  These secre-
tions serve primarily to moisten the ingested material and mouth tissues, and
to initiate the breakdown of ingested starches.   Mastication serves to break
up the material mechanically.

     The ingested material then passes through the pharynx and into the
esophagus, a short mucous-lined tube capable of producing wave like peristaltic
motion that aids in moving material to the stomach.  In the stomach lining,
there are a number of specialized glandular cells whose function is to secrete
digestive enzymes, buffers, hormones and hydrochloric acid.  Ovoid parietal
cells, in the lining, are stimulated by the vagus nerve, gastrin and histamine
to secrete HC1 into the lumen of the stomach.  Mucous and alkaline fluids,
secreted by the stomach lining, protect the stomach from being eaten away by
the acid, which may range anywhere from pH 0.9-3.0 depending on the nature of
the ingested material and the overall health of the individual.  Some fluid
absorption occurs in the stomach.

     As the ingested material proceeds along its course into the duodenum of
the small intestine, it is acted upon by alkaline pancreatic juices, NaHCOs,
insulin, glucagon, enzymes and proteins from the pancreas, bile from the liver
and gall bladder; and secretin, duodenal juice, succus entericus and pancre-
ozymin from the intestinal cells.  The thick carpet of finger-like projections
(villi) that line the small intestine allow for greater surface area and there-
fore more absorption.  Most of the liquids, amino acids, sugars and other
nutrients are taken up into the bloodstream via capillary beds among the villi
and the hepatic portal vein (leading to the liver).  This transport can occur
by means of absorption, persorption or pinocytosJ.s.
                                      321

-------
     The non-assimilated portion of the'ingested material proceeds to the large
intestine where water, salt and glucose are absorbed from the fecal material.
The fecal material then passes through the rectum and out the anus.

     In man, the time period for the complete passage of non-assimilated
ingested material will vary with each member, but usually ranges between
20 and 25 hours.
                                     322

-------
            DISCUSSION ON THE ROUTES OF EXPOSURE:   INHALATION,
                   DEPOSITION AND CLEARANCE OF PARTICLES

REMARK    (Dr.  Gross):   I am associated with the Industrial Health Foundation.
          I wish to comment  on some  of  the  statements that have just been made.

          I have been a pathologist  over the last 50 years.  Half of that time
          was in hospitals where  I spent a  good deal of time studying the tis-
          sues of hospital patients  who died as a result of their illness.
          One of the organs  that  was studied in great detail was the kidney.

          I have always been Impressed  from a clinical point of view upon the
          exquisite ability  of the circling unit of the kidney to hold back dis-
          solved molecules of proteins  that have a fairly high molecular weight
          and allow molecules of  low molecular weight such as electrolytes
          to pass through.

          When one considers the  comparative size of a particulate, particu-
          larly a fiber, in  relation to a micro-molecule such as albumin, which
          under normal conditions the circling membrane of the glomerulus (a
          unit in the kidney) holds  back, there is an enormous difference and
          according to what  Dr. Millette just said, quoting Dr. Cook's
          work, the passage  of participates through the renal circling membrane
          is not an unusual  event.   This is totally out of keeping with what we
          know of kidney function, the  ability of the membrane of the glomerulus
          to hold back even  dissolved molecules of appreciable size.

          With regard to the passage of particles through the intestinal mucosa
          Dr. Millette quoted Volkhelmer, who in his article claimed to find
          starch granules in the  blood, in  various  tissues, and in the urine.
          These starch granules are  10  times the size of a red corpuscle and in
          order to pass, say through the intestinal wall into a blood vessel
          of any size it ultimately  will have to pass through the capillary
          network that barely allows a  single red corpuscle to pass through.
          Yet,  we are supposed to believe that Volkhelmer was able to demon-
          strate such huge particles in the urine.

          As an example of the ability  of the intestinal mucous membrane to
          hold back particles that happen to be in  the  intestinal ileum, I
          might mention that coal miners swallow a  good deal of the dust that
          they inhale and in the  swallowed  coal dust are particles that are a
          fraction of a micron in diameter.  If fibers, which are 1 micron
          in diameter, are capable of passing through the intestinal wall,
          then particles that are a  small fraction  of that size would have even
          a greater facility to pass through.  Now, a coal miner may work in a
          coal mine for 30 years  and every  day he would swallow a fairly large
          amount of coal dust that he has inhaled and was brought up from his
          lungs, yet when one does autopsies, as I  have done, on coal miners
          one does not see black  discoloration of the lymph nodes.  One rarely
          sees black spots in the liver and spleen, but that can be explained
          on the basis of lymphatic  drainage from the lungs.  But, one  cannot
          see black lymph nodes in the  mesentery, the lymph  glands  that drain
          the intestinal wall. One  does not see that and  one would  see it  if
          particles were capable  of  penetrating the intestinal wall.

                                     323

-------
          You realize, of course, that I look with a very jaundiced eye on this
          presentation and I hope the audience will also be judicial in accept-
          ing this presentation.

REMARK    (Dr. Kotin):  I work for Johns-Manville Corporation.   A couple of
          comments on the papers and then perhaps a few generalizations.

          First, let me thank you, Dr. Rowe, for being sensitive enough to
          dedicate this session to Mearl Stanton.  As a former associate of
          his at NCI there is no way we can overstate our debt to him and his
          associates.  Also thanks for being good enough to stop me in the cor-
          ridor to say I can talk for a few minutes if I want.

          I am not sure that the case for penetration of the gut has been made
          by this presentation, but penetration of the gut does occur and I
          think that the criteria for penetration are probably not for this
          session.

          I think that Dr. Millette might be well advised to know that both
          Doctors Cunningham and Pontefract were aware belatedly that the
          formaldehyde that they used for the fixation of tissues was loaded
          with asbestos fibers.  Unfortunately it was filtered through asbestos
          and I think they are very candid in stating this, but in no way
          would I say that that necessarily throws out all of their data.  I
          think quantitatively it might be challengable.

          Again, I think the best thing that can be said about the Storeygard
          and Brown study is what Dr. Brown says himself.  They were dealing
          with an exteriorized loop of intestine.  He cannot be sure that he has
          got penetration or overlay on many of the sections, which I reviewed
          with him personally, so let us at least maintain the fact that maybe
          not these studies but others may very well substantiate the concept
          of penetration.

          Dr. Lippmann, I think you might know that, and I am sure you are
          aware that Crystal and his associates at the Heart and Lung Insti-
          tute are beginning to show, I think rather reliably and consistently,
          a role for the poly as well as for the macrophage in the fibrogenic
          capabilities.  I think this has some relevance to the pathogenesis
          of a disease in people who are exposed to excessive amounts of
          asbestos.

          Again,  I have no new data to present because of the brevity of time,
          but let me restate a few verities that probably have been lost
          sight of and certainly I think have been given short shrift in the
          presentations.

          Let me  begin immediately by saying that the reality of asbestos-
          related disease has been amplified by the presentations at this meet-
          ing.  I think at the very least you would have to have your sanity
          questioned to doubt the capability of excessive amounts of asbestos
          fibers  to  produce an array of asbestos related conditions.  However,

                                      324

-------
the disease-producing potential can not be divorced from accepted princi-
ples of pharmacology, toxicology, pathogenesis, pathology and clinical
disease.  Specifically, these principles include factors like dose
response; multifactorial etiology in both disease development and
disease natural history; the demonstration by several, including a
person attending this conference, of a no adverse- effect level in a
very competently studied population; and the necessity for biological
availability for host effect, which, of course, relates to the two
earlier presentations.  This includes things that have been discussed
before; localization, retention, translocation, the dimension of the
particles, the solubility of the particles, and I think all these
principles, and one could go on listing many more, find expression
and are all applicable to the problem of asbestos exposure and one
that is particularly relevant to EPA.  I do not envy EPA's responsi-
bility in trying to address the issue of asbestos outside the work
place.  OSHA has by far the easier of it.

The patterns of asbestos-related disease in occupational settings
are well known.  The patterns of asbestos response in para-occupational
settings, neighborhood studies, and family studies have not been
shown and this does not mean that the positive studies are useless.
Not at all.  What they do clearly demonstrate is that even outside the
workplace dose response has its universal application.

Perhaps a fourth pattern of exposure to asbestos-related disease,
and this does put the EPA right in the middle of the circle, is a
category, for want of a better term, I call "living with asbestos."
This includes the school buildings.  This includes asbestos as part
of the earth's crust where it is indeed part of the potable water
supply or part of the airborne suspended material as a result of
wind and soil erosion.  For this group, really, and I can only
repeat what Dr. Rowe said, the data are pitifully little and really
do not permit conclusions nearly as much as they permit what Sir
McFarland Burnett called in his Nobel speech, "responsible specula-
tion."  The data do permit responsible speculation that the "living
with" group does not have any asbestos-related disease as yet.  One
gives added credence to the negative data because you do have two
marker situations, mesothelioma and a rather characteristic type of
fibrosis.  But this is not to say that the answer is in by a long
shot.

Then you have the fourth category and this is  the casual exposure  and
I mean casual not in the cultural sense.  I mean casual in a quantita-
tive sense; not the people in this room; you either work with asbestos
or are using it in your laboratory or so on, but the next crowd  that
goes to see the Redskins play would predominantly be people casually
exposed.  Here, again, I think despite ongoing studies that have been
comprehensive, yet inadequate, there is absolutely no evidence of  an
effect.

I would make two major closing comments.  First,  the  assumption  that
all four classes are interchangeable in  terms  of  the  generalizations
I have made is not true of course.  The dosage of exposure  is different,
                             325

-------
           the  co-factors differ and so on.   So,  I think one has  to be very,
           very jealous in terms of  the discipline in which one approaches each
           of these categories and tries to  conclude from one  to  the  other.

           The  second point I would  like to  make  is that the four categories,
           again,  in no way contradict the occupational information that we have
           about asbestos but, again, I would emphasize the importance of dose.
           The  assumption that doses, particularly in the para-occupational
           exposures, are low dose exposures, I do not  think is a valid one on
           the  basis of existing data, but the data are so pitifully  small that
           one  cannot either deny or assent; one  can only say  that much more
           information is necessary.   Again, a short exposure  is  not  necessarily
           a low dose exposure and a nonoccupational exposure  may not be, either.

           Let  me  close by saying one word on substitutes.  Clearly the princi-
           ples of biology that are  applied  to asbestos have to be applied to
           all  substitutes, as 1 know in fact they are  being applied, but it
           would be well to not repeat some  of the omissions in our approach
           to the  asbestos problem that have been taking place over the last
           half century in addressing these  substitutes.

 QUESTION  (Mr. Kosner):   I am from  the NIEHS.  We certainly owe  a great debt
           to Dr.  Kotin who is also  the founding  director of the  National
           Institute of Environmental Health Sciences,  the institute  that I am
           with at the present time.

           We do know that asbestos  is associated with  mesothelioma of the pleura
           and  of  the peritoneum.  Unless we believe these substances act at a
           distance, we would have to believe that the  particles  must get to
           these sites in order to set up the conditions for the  effect to occur.

           I wonder if something also could  be said about the  stability of dif-
           ferent  types of fibers.   For example,  asbestos is quite different than
           fiberglass and some others in terms of its resilience  and  in terms of
           its  strength and some other factors.   It may be that some  of these
           stay pretty much as they  are,  whereas  other* ones tend  to break up and
           might be eliminated more  rapidly.   The way more sense  is going to be
           made from this field in which so  many  different substances are being
           used is to find out these basic principles of uptake and release and
           integrity.   We do know something  about the Importance  of the length
           to the  diameter.

           Does Dr.  Millette know something  about the integrity of different
           types of fibers;  rock wool versus fiberglass versus asbestos, et
           cetera?

ANSWER     (Dr.   Millette):   In terms  of ingestion there certainly is  very little
           data on  any material other than asbestos that has even been attempted.
           So,  all  you would have would be the casual findings of certain other
           types of fibers in other  tissues,  such as, gastrointestinal tissues,
           or finding, say,  attapulgite fibers in the urine of a  person receiv-
           ing  it in a high medical dose.  So, very little really has been done
          with that.
                                      326

-------
REMARK    (Dr. Rowe):   That was a very good comment and question.  I think
          that is an area that will have to be avidly pursued in the
          future.
                                    327

-------
                       MAN-MADE VITREOUS FIBERS  AND HEALTH

                                       by

                               Jon L. Konzen, M.D.
             Medical Director, Owens-Corning Fiberglas Corporation
                Chairman,  Medical & Scientific Committee of TIMA
                              Mount Kisco, New Tork


                                    ABSTRACT

    Asbestos fibers and manmade vitreous fibers differ  in durability, fate and
    ability to cause disease.  In man, asbestos is known to cause botb malignant
    and non-malignant disease.  In man, there is no  credible evidence of malignant
    or chronic progressive non-malignant disease resulting from exposure to
    man-made vitreous fibers.

    Airborne exposures of man-made vitreous fibers observed during manufacture,
    fabrication and installation are extremely low.  With .few exceptions, they
    are well below 1 fiber per milliliter.

    No chronic progressive disease, either malignant or non-malignant, has been demon-
    strated to date by Inhalation of man-made vitreous  fibers in animal studies.
    Animal models demonstrate disease only as a result  of non-physiologic exposure
    to long thin fiber by surgical implantation (mesothelioma) and by intratracheal
    injection (fibrosis).
GENERAL

     Man-made vitreous fibers which  include fibrous glass, rock and slag wool
and ceramic  fibers are products of 20th century technology.  Mineral and slag
wool were  first manufactured in the  early years of this century while fibrous
glass was  first produced in the 1930*s  and ceramic fiber roughly a decade
later.  These materials are used for thermal and accoustical insulation and
reinforcement applications.  Presently  only a few of these applications overlap
with asbestos usage and, therefore,  man-made vitreous fiber cannot he considered
truly a substitute for asbestos.

DIFFERENCES  - ASBESTOS VS MAN-MADE VITREOUS FIBER

     Vitreous fibers have come under suspicion as possible malignant or non-
malignant  disease producing materials largely because they are fibers.  The
dimensions of the smaller vitreous fibers overlap the dimensions of the larger
asbestos fibers.  The similarity ends there.  It is useful to  contrast man-made
vitreous fibers and asbestos in terms of durability and  fate.
                                       329

-------
Durability

     Fibers vary significantly in their durability or survival in living tissues.
Gypsum disappears within hours after implantation, whereas some types of asbestos
fibers can survive within tissues for the full life-span of exposed animals and
humans.  Between these two extremes there are varying intervals of durability
for fibers of many types.  Experimental studies1  (e.g., Kuschner and Wright)
report data suggesting that very fine man-made vitreous fibers have a marked
tendency to disappear when compared to asbestos fiber.

     Both in vitro and in vivo studies have shown that man-made vitreous fibers
have a greater solubility than many asbestos fibers.  (This should not be sur-
prising when one considers the recognized variations in solubility among the
several types of asbestos).  Kuschner and Wright reported a fibrogenic response
to very thin glass fibers (less than one micron in diameter), but, paradoxically,
no biological effect of ultrathin fibers (less than 0.3 microns in diameter).
After special efforts were made to ensure that this finding was not an artifact,
the researchers were reasonably convinced that it was related with the dis-
appearance of fibers.

Fiber Fate

     Experimental studies in animal models and in humans have demonstrated that
fibers can undergo cleavage, splitting, or fragmentation in the lungs.1'2  This
property varies among fibers, and, in fibrogenesis and cancer induction, it is
of critical importance.  Asbestos fibers are multifilamentous and split longi-
tudinally, or along the long axis, into progressively thinner components that
have been shown to be associated with chronic, progressive non-malignant and
malignant disease in humans.  Asbestos fibers fragment transversely with much
less ease and frequency.  In sharp contrast, man-made vitreous fibers are mono-
filamentous and do not split longitudinally into fibrils.  Rather, they split
and fragment only along.the transverse axis, thereby becoming progressively
shorter.3  When one looks at the hilar lymph nodes draining the lungs of
experimental animals, one can find fragments of vitreous fiber shorter than
that to which the animals were exposed; thus some of the fibers may have been
broken up in the lungs.  With the long thin fiber concept, in which short
fibers are recognized as being non-pathogenic, this property of man-made
vitreous fibers moves them in the direction of less and less pathogenicity.

MAN-MADE VITREOUS FIBER PRODUCTS

     Man-made vitreous fibers are produced in two broad categories:  wools and
textiles.  Man-made vitreous fiber wool is used for example in commercial,
industrial and residential insulation; acoustical ceiling panels; air-conditioning
ducts; and mat products.  The textile fibers or glass fiber yarns, roving and
chopped strand mats have numerous applications including decorative and indus-
trial fabrics; reinforcements for plastics, rubber and paper; electric insul-
ation; filtration; and roofing materials.
                                      330

-------
FIBER DIMENSIONS AND RANGES

     Man-made vitreous fiber manufacturing processes, especially the wool pro-
cesses, do not produce fibers with absolutely uniform diameters.   The diameters
of the fibers in each product vary, hence the diameter of the majority of fibers
in the product determines the "nominal diameter".   If the actual diameters of
man-made vitreous fibers produced by a particular process are plotted on a graph,
the overwhelming majority of them will be "near" the nominal diameter.  Gen-
erally, the further from the nominal fiber diameter one gets, the fewer fibers
one will find - giving what often looks like a bell-shaped curve when the fiber
diameters are plotted.

     Although the vast majority of all man-made vitreous fibers products have
a nominal diameter of 6 microns or greater, all products contain some fibers
with diameters equal to or less than 1.5 microns.   For over fifty years workers
have been exposed to some fibers equal to or less than 1.5 microns in diameter
contained in all products.  Epidemiological studies of this worker population
have failed to identify credible evidence of chronic, progressive non-malignant
or malignant disease associated with this exposure.

Wool Fiber

     Wool fibers are amorphous silicates made by blowing or spinning (fiberizing)
a stream of molten vitreous material into fibers.   Rock or slag wool fibers
traditionally are made from furnace slag and/or limestone.  In recent years,
raw materials such as basalt, iron slag and phosphate slag have been used.  Fib-
rous glass wool fibers are made from glass compositions that are carefully con-
trolled formulations of silicon* aluminum, boron,  calcium, sodium and other
metal oxides.

     Most products manufactured from the wool processes contain fibers that
range in nominal diameter from approximately 6 to 9 microns.  However, such
products manufactured for over 50 years always have contained a small percen-
tage of fibers with diameters equal to or less than 1.5 microns with lengths
varying from 5 to 60 microns.

Textile Fibers

     Textile fibrous glass products generally have larger nominal diameters
than man-made vitreous wool fiber products.  These textile fibers are drawn
or extruded from holes in the base of the fiberizing equipment in a process
which produces continuous fibers of infinite length, nominal diameters ranging
from 6 to 25 microns and a very narrow range of diameter distribution.  The
majority of textile fibrous glass is used in reinforcement applications where
a larger fiber diameter is desired for its superior reinforcing properties.
For this reason, most of the textile fibrous glass produced are the larger
diameter fibers.  The finest diameter textile fiber, which has a nominal dia-
meter of approximately 4 microns, is produced in relatively small quantities
and is used for specialized fabric applications.  Because of the controlled
manufacturing process, textile fibrous glass contains only a minute amount of
fiber with diameters less than or equal to 1.5 microns.
                                      331

-------
Fine Diameter  Fibers

     Fine diameter  fibrous  glass, which  is produced by a flame-attenuated pro-
cess, may include fibers  that  have  a nominal diameter as low as 1 micron.
These fibers have been produced  on  a commercial basis since the early 1940's
in  limited  quantities.*

Very Fine Diameter  Fibers

     Very fine diameter fibrous  glass, with a nominal diameter of less than 1
micron,  is  manufactured for certain highly specialized applications, such as
aerospace insulation  and  sophisticated filtration and represents less than
1 percent of all production.

Ceramic  Fibers

     Ceramic fibers are wool-like products made from molten aluminum silicate.
They have a nominal diameter of  approximately 2 to 4 microns and a range of
actual diameters from 0.5 to 12  microns,  skewed towards the larger diameter
fibers.  These fibers  are primarily used for high temperature applications in-
cluding  thermal blankets  for industrial  furnaces and vacuum cast parts for
speciality  products used  in high temperatures.

BIOLOGICAL  EFFECTS  OF  MAN-MADE VITREOUS  FIBERS

     Investigations into  the health effects of man-made vitreous fibers can
best be  discussed under the headings of  sampling studies, animal studies, in
vitro studies  and human studies.  These  fibers which have been in commercial
use, for over  50 years, have failed to demonstrate any chronic, malignant or
non-malignant  pulmonary disease  in  man.   In laboratory animals disease has
been produced  only  when fibers were administered by an artificial route which
bypassed physiologic defenses.   The airborne concentrations of man-made
vitreous fibers have consistently been demonstrated to be remarkably low,
both in  areas  of manufacture as  well as  in areas of handling, application
(with the exception of blowing applications) and use.  Each of these points
will be  reviewed briefly, touching  only  on the most important aspects.  No
attempt  will be made to cover  every article which has been written on the
subject.

I.  Industrial Hygiene Studies

     Several industrial hygiene  studies  have been reported.5  The results of
these studies  are remarkably consistent.  In general the airborne fiber con-
centration in  ordinary wool fibrous glass manufacturing operations is 0.1
fiber or less  per milliliter for airborne fibers less than 3.5 microns in
diameter with  about 25  percent of this material less than 1 micron in diameter.
It is unusual  to find  airborne concentrations approaching 1 fiber per milli-
liter.   While  the lengths were variable, the majority of the fibers noted were
longer than 10 microns.  In the  finer diameter fiber products (average diameter
of 1 micron or  less) the airborne concentration may exceed 1 fiber per milli-
lite*r in manufacturing  and  fabrication areas.  Esmen6 demonstrated that,
generally,  speaking, as the nominal diameter of the products increased the

                                      332

-------
airborne concentration decreased.  Similar findings were demonstrated in fabri-
cation* packing and cutting areas of the plants.  Industrial hygiene findings
have shown that ftfr any wool product, the average diameter or airborne fiber
resulting from manufacture or fabrication operations will be smaller than the
average diameter of, the product.  As an example, the average diameter of build-
ing insulation runs from approximately 6 to 9 microns while the average dia-
meter of airborne fiber resulting from the manufacture or fabrication of this
material will be in a range of approximately 1 of 2 microns.  It can be gen-
erally stated that the light microscopic counts will be approximately equal
to the electron microscopic counts for ordinary type fibrous glass.  This
does not hold true for the special finer fiber products (average product dia-
meter of 1 micron or less) where the electron microscopic count may be greater
than the count by light microscopy.

     Esmen,7 in a recent study for the Thermal Insulation Manufacturers Asso-
ciation to determine airborne fiber concentrations in operations utilizing
man-made vitreous fibers, has demonstrated that during a field installation
of thermal insulation materials including ordinary building insulation,
acoustical ceiling and fibrous glass duct insulation, the average airborne
concentration of fibers was well below 1 fiber per ml with the exception that
during the application of blowing wool into closed attic spaces the time-weighted
average airborne concentration ranged up to 6 fibers per ml.

     In this same study, Esmen reported industrial hygiene sampling of aircraft
insulation fabrication where the material was being sewed, cut and cemented.
This material is high efficiency, specialized insulation which is 1 micron in
nominal diameter.  The airborne concentration was generally below 1 fiber per ml.

II.  Animal Studies Involving Man-Made VjLtreous "Fibers

     Although animal studies have been undertaken since the 1930's, the most
pertinent studies include Gross'8 inhalation study in 1970 where he exposed
rats and hamsters to 100 mg per cubic meter of air of fibrous glass that had
a nominal diameter of approximately 1 micron and a diameter in the chamber
air of 0.5 microns.  Seventy percent of the airborne material was reported to
be fibrous.  The fiber lengths were between 5 and 20 microns.  These studies
demonstrated no appreciable alteration of lung architecture, minimal pleural
change, no significant fibrosis and no tumor development in animals exposed
for 24 months and domiciled for the remainder of their lifetime.  Other inhala-
tion studies by Botham and Holt,9 Timbrell,10 Harris,11 Harris and Fraser,12
Lippmann13 and Brain1** utilizing fibrous glass, designed to look at such things as
deposition and clearance as well as pathological changes, demonstrated
non-specific pulmonary responses with a relatively wide variation but no tumor
formation or significant fibrosis.

     Wagner,15 in England, has recently reported that his inhalation experi-
ments utilizing a very fine diameter fibrous glass with a mean diameter of 0.3
microns and rock wool with a mean diameter of 0.8 microns, have failed to
demonstrate fibrosis with the only reaction being a minimal non-specific cellu-
lar dust response.  This study is still on-going and must await completion  for
final evaluation.
                                      333

-------
     A number of  Intratracheal  injection studies have been carried out over
 the years beginning  in  the  late 1930's.  The more significant studies were
 those carried out by Gross,8  and by Wright and Kuschner.1  These studies
 demonstrated a wide  variety of  cellular response with no significant chronic
 pulmonary effects, with the exception of the Wright-Kuschner study.  Wright
 and Kuschner demonstrated a peribronchiolar fibrosis in guinea pigs intra-
 tracheally injected  with long thin fibrous glass.  This response was qualita-
 tively similar to a  response  to chrysotile asbestos but quantitatively much
 less.  The authors commented  that this information could not be directly
 extrapolated to man  because the method or administration bypassed all natural
 respiratory defense  mechanisms.  The study did show, however, that massive
 doses artificially placed at  the target site caused fibrosis if the fibers
 were significantly long and thin (less than 1.5 microns in diameter and
 greater  than 10 microns in  length).  The authors felt that additional inhala-
 tion studies using long, thin fibers were indicated.  Such studies are now
 being conducted.

     Quite significantly, malignant tumors have not been produced by intra-
 tracheal injection of man-made  vitreous fibers with dimensions known to
 produce  them by surgical implantation.  The Wright-Kuschner intratracheally
 injected animals  were sacrificed after 2 years and Gross8 animals, similarly
 exposed, were permitted to  live out their lives.

     Intracavitary implantation in animals of man-made vitreous fibers as
 well as  a variety of other  fibrous materials has been carried out by a number
 of investigators16'17'18'19'20  in this country and abroad.  Mesotheliomas have
 been produced at  the sites  of surgical implantation and injection into the
 pleural  and peritoneal  cavities of animals using high doses of many types of
 materials.  The materials included specially prepared long, thin fibrous glass
 fibers  (fibers less  than 1.5  microns in diameter and greater than 8 to 10
 microns  long).  The  implantation of the type of fibrous glass commonly used
 as insulation material  however,  which does contain some fibers less than 1.5
 microns  in diameter, failed to  elicit mesothelioma production.21  Stanton,16
 who performed the major surgical implantation study, noted that "Direct appli-
 cation of our results (the  implantation study findings) to the problems in man
 would be unwise because of  the  method of application and the high doses used
 are remote from the  usual exposure of man to fibers ..."

 III.  In Vitro Effects

     A number of  studies have been conducted in vitro.  The reported results
 have been mixed.22'23   The  question arises for the need to test man-made
vitreous fibers in an in vitro  system since it has been demonstrated in vivo
 that long thin fibers,  when implanted into the abdominal and chest cavities,
 do cause mesotheliomas.  It is  suggested that the human health effects of
man-made vitreous fibers are  best evaluated through further animal studies and
by epidemiology.  Such  studies  are currently underway.  The progress of one
of these studies  is  being reported here at this symposium.
                                      334

-------
IV.  Cross Sectional Studies of Currently Exposed Workers

     Cross sectional studies have been carried out since 1942 on man-made
vitreous fiber exposed workers.  These studies have been largely fibrous glass
exposed workers.  Several of these studies have been carried out at the same
plant.  That facility is the oldest continuously producing fibrous glass plant
in the United States.  This plant has been repeatedly studied by Wright, by
deTreville, by Nasr and by Utidjian utilizing cross sectional morbidity techni-
ques.  Wright   studied 1389 fibrous glass workers who were employed from 10
to 25 years.  The study demonstrated no unusual pattern on chest roentgenograms
that could be attributed to fibrous glass exposure.  Utidjian25 reported the
evaluation of 232 randomly selected workers from this same plant.  The study
demonstrated no major effect on lung function after long term exposure.
deTreville,26  using a subsample of Utidjian's workers, which included 30 long
term fibrous glass workers, 15 with minimal and 15 with heavy subjective
exposure, evaluated the subjects for cardiac and pulmonary status including
blood gas studies.  He noted no significant differences between the two groups
of exposed workers.  Nasr,27 examining 2028 chest x-rays of fibrous glass
workers in this plant, observed no difference in the Incidence of abnormalities
between the exposed factory workers and non-exposed office workers and no
radiographic effects resulting from fibrous glass exposure.  Hill,28 in evalu-
ating 70 workers with occupational exposure to fibrous glass with an average
exposure time of approximately 20 years, found that chest x-rays and pulmonary
function studies of the workers were not significantly different from an un-
exposed group matched for age, height and weight.

     Gross,29 comparing the lungs of 20 insulation fibrous glass manufacturing
workers whose periods of exposure ranged from 16 to 32 years to the lungs of
26 urban dwellers with no history of fibrous glass exposure in the workplace,
noted no significant difference in lung fiber content or fiber dimensions
between the groups.  He further concluded that long term exposure to the dust
of fibrous glass caused no gross or microscopic pulmonary damage.

     Upper respiratory irritation has been reported by several authors.30*31'32'
33'3lf It is often found following unusually dusty conditions, particularly in
situations involving the dry method of tearing-out of installed man-made vitreous
fiber materials.  After the initial irritation has passed there is complete
resolution of the condition.

     Transitory skin irritation by man-made vitreous fibers in some workers
is known to occur.  This has been reported by many authors35'36'37'38'39 over
the years.  All authors agree that it is a mild, mechanical irritation which
lessens in intensity after several days of continuous occupational exposure.
The ability to cause irritation is related to the diameter of the fiber.  The
larger the diameter of the fiber, the more likely the material is to cause
irritation.  There is no evidence that the skin irritation is other than a
transitory mechanical one.  There is no allergic component.

V.  Mortality Studies Involving Man-Made Vitreous Fibers

     The above mentioned cross sectional morbidity studies are useful in iden-
tifying a lack of non-malignant "dust related" disease.  However, such  studies

                                      335

-------
could fail  to demonstrate disease which had a long latent period.  For this
reason, epidemiological mortality studies of workers with long exposure to
airborne fibrous glass in manufacturing operations have been done.  Such studies
have been carried out and are currently in progress.  Among these studies is
Bayliss l**°'t*1'1*2 work which  included 1448 workers occupationally exposed to
fibrous glass.  This study found no significant malignant respiratory disease,
20  or more  years after onset of fibrous glass exposure.  The author did note
19  non-malignant respiratory disease deaths, excluding pneumonia and influenza,
compared to an expected 10 deaths.  However, more than half of the decedents
had previous exposure in dusty environments, including nine in a foundry, one
in  a silica batching operation and one with an exposure in coal mining.  Fur-
ther, smoking histories were not available.  The plant population used in the
Bayliss study was the same as used on different occasions by Wright, Nasr,
Utidjian and deTreville.  Therefore, it seems likely in light of the work his-
tories involved that any significant non-malignant respiratory disease would
have been discovered by these studies.  The proposition that susceptibles
would select themselves out  of the working population is not realistic.  A
case in point is the all too common findings of asbestosis—a legacy of past
exposure—being identified in current asbestos exposed workers.

     The Bayliss case control study, which attempted to study malignant and
non-malignant disease in manufacturing workers exposed to finer diameter fiber
(1  micron average diameter)  was inadequately designed and analyzed, and
incorrectly classified some  of the workers as having contact with finer fiber.
The results were reported as borderline statistically significant.

     Recently Enterline^ reported his findings on the first eight plants in
a study that will encompass  17 man-made vitreous fiber manufacturing facilities.
This study  has not  considered smoking histories, which were unavailable.  The
initial study group of eight plants included 7049 workers, 6023 workers from
five fibrous glass  manufacturing plants and 1026 workers from three rock wool
or  slag wool plants.  Compared to expected deaths from all causes in the United
States, the initial report indicated 7 percent fewer deaths among the cohort.
Twelve percent fewer deaths  than expected were attributed to respiratory can-
cer.  Thirteen percent fewer deaths than expected were attributed to malignant
disease of  the digestive organs or peritoneum.  Five percent more deaths than
expected were attributed to  non-malignant respiratory disease excluding influenza
and pneumonia.  None of these deviations is statistically significant.  An
important point is  that while the Enterline study noted fairly wide variations
in mortality ratios between  plants, each with a relatively small number of
employees,  the mortality ratios of the plants as a group were close to 100,
which is the expected statistical norm.  The author has stated he does not
believe there is any evidence in his study of an excess in malignancies due to
man-made vitreous fiber in the plants he has studied to date.4"1

     Another recent study by Robinson1*5 reported on a cohort of 595 workers
from just one of the rock wool plants included in the Enterline study.  The
resulting standard  mortality ratio for all causes of death was lower than the
adjusted United States population.  The author suggested that lung cancer,
non-malignant respiratory disease and digestive cancer showed a progressive
rise related to time from first exposure.  This was evident in workers exposed
for more than 30 years.  However, there were no statistically significant

                                      336

-------
excesses of malignant or non-malignant respiratory disease or digestive cancer
for the entire cohort.  The numbers were extremely small and a careful examina-
tion of the data does not demonstrate any consistent pattern for malignant
respiratory disease, non-malignant respiratory disease or digestive cancer.   The
healthy worker effect and the fact that smoking histories were not considered
also must be kept in mind when interpreting the data.  The Enterline study,
encompassing a much larger group of workers, is more pertinent and indicates
no significant excess for these causes of death.

     Very recently a report1*6 has been received on a retrospective cohort
study of 6536 fibrous glass production workers—all from one company but in
multiple plants—who worked 10 or more years with some portion of that employ-
ment between 1968 and 1977.  A special component of this investigation was an
analysis of a long term cohort of 1240 individuals with 20 or more years of
employment and 30 or more years latency.

     Analysis of the data reveals that for any cause of death there was no
marked excess or statistically significant increase in mortality.  In fact,
the pattern of mortality for fibrous glass production workers appears con-
siderably lower than comparable U.S. patterns.  Long-term workers enjoyed
an even more favorable mortality experience than those employed for shorter
periods.

SUMMARY

1.   Asbestos fibers and man-made vitreous fibers differ in durability,
     fate and ability to cause disease.  In man, asbestos is known to
     cause both malignant and non-malignant disease.  In man, there is
     no credible evidence of malignant or chronic progressive non-malignant
     disease resulting from exposure to man-made vitreous fibers.

2.   Airborne exposures of man-made vitreous fibers observed during
     manufacture, fabrication and installation are extremely low, with
     few exceptions, well below 1 fiber per milliliter.

3.   No chronic progressive disease, either malignant or non-malignant,
     has been demonstrated to date by inhalation of man-made vitreous
     fibers in animal studies.  Animal models demonstrate disease only
     as a result of unnatural exposure to long thin fiber (less than
     1.5 microns in diameter and greater than 10 microns long) by
     surgical implantation (mesothelioma) and by intratracheal injection
     (fibrosis).

REFERENCES

1.   Wright, G. and M. Kuschner.  The Influence of Varying Lengths of Glass
     and Asbestos Fibers on Tissue Response in Guinea Pigs.  Inhaled Particles
     IV.  Edited by W. H. Walton.  Pergamon Press, Oxford and New York,
     pp. 455-474, 1977.

2.   Pooley, F. D.  Electron Microscope Characteristics of Inhaled Chrysotile
     Asbestos Fiber.  British Journal of Industrial Medicine. 29:146-153, 1972.

                                      337

-------
3.   Assuncao, J. and M. Corn.  The Effects of Milling on Diameters and Lengths
     of Fibrous Glass and Chrysotile Asbestos Fibers.  American Industrial
     Hygiene Association Journal,  pp.  811-819, 1975.

4.   Smith, H. V.  History, Processes,  and Operations in the Manufacturing
     and Uses of Fibrous Glass — One Company's Experience.  In Occupational
     Exposure to Fibrous Glass — Proceedings of a Symposium, HEW Publication
     No. (NIOSH) 76-151, pp.  19-26, 1976.

5.   Dement, J. M.   Environmental Aspects of Fibrous Glass Production and
     Utilization.  Environmental Jlesearch, 9:295-312, 1975.

6.   Esmen, N., et al.  Summary of Measurements of Employee Exposure to Air-
     borne Dust and  Fiber in  Sixteen Facilities Producing Man-Made Mineral
     Fibers.  American  Industrial Hygiene Association Journal, 40:108-117,
     1979.

7.   Esmen, N., et al.  Estimation of Employee Exposure to Total Suspended
     Particulate Matter and Airborne Fibers in Insulation Installation Opera-
     tions.  A Report to the  Thermal Insulation Manufacturers Association,
     1980.

8.   Gross, P., et al.  The Pulmonary Reaction to High Concentrations of
     Fibrous Glass Dust.  Archives of Environmental Health, 20:696-704, 1970.

9.   Botham, S. K. and  P. F.  Holt.  The Development of Glass Fiber Bodies
     in the Lungs of Guinea Pigs.  Journal of Pathology, 103:149-156, 1971.

10.  Tlmbrell, V.  The  Inhalation of Fibrous Dust.  Annals of the New York
     Academy of Sciences.  132:255-273, 1965.

11.  Harris, R. L.   Aerodynamic Considerations:  What is a Respirable Fiber
     of Fibrous Glass?  In Occupational Exposure to Fibrous Glass — Proceedings
     of a Symposium, HEW Publication No. (NIOSH) 76-151, pp. 51-56, 1976.

12.  Harris, R. L. and  D. A.  Fraser.  A Model for the Deposition of Fibers
     in the Human Respiratory System.   American Industrial Hygiene Associa-
     tion Journal, 37:73-89,  1976.

13.  Lippman, M., et al.  Deposition of Fibrous Glass in the Human Respiratory
     Tract.  In Occupational  Exposure to Fibrous Glass — Proceedings of a
     Symposium, HEW  Publication No. (NIOSH) 76-151, pp. 57-61, 1976.

14.  Brain, J.  D., et al.  Pulmonary Distribution of Particles Given by
     Intratracheal Instillation or by Aerosol Inhalation.  Environmental
     Research,  11:13-33, 1976.

15.  Wagner, J.  C.  MRC Pneumoconiosis Unit of Llandough Hospital, Penarth
     United Kingdom, to Dr. Paul Kotin, Senior Vice President of Health,
     Safety and Environment for Johns-Manville Corporation:  letter dated
     April 17,  1980.


                                     338

-------
16.  Stanton, M. F. and C.  Wrench.  Mechanisms of Mesothelioma Induction With
     Asbestos and Fibrous Glass.  Journal of the National Cancer Institute,
     48:797-821, 1972.

17.  Stanton, M. F.t et al.  Carcinogenicity of Fibrous Glass:  Pleural
     Response in the Rat in Relation to Fiber Dimension.  Journal of the
     National Cancer Institute, 58:587-597, 1977.

18.  Pott, F.  Some Aspects on the Dosimetry of the Carcinogenic Potency of
     Asbestos and Other Fibrous Dusts.   Staub-Reinhalt, 38:486-490, 1978,
     (translation).

19.  Wagner, J. C., et al.   Mesotheliomata in Rats After Inoculation with
     Asbestos and Other Materials.  British Journal of Cancer, 28:173-185,
     1973.

20.  Wagner, J. C., et al.   Studies of  the Carcinogenic Effects of Fiber Glass
     on Different Diameters Following Intrapleural Inoculation in Experimental
     Animals.  In Occupational Exposure to Fibrous Glass — Proceedings of a
     Symposium, HEW Publication No. (NIOSH) 76-151, pp. 193-197, 1976.

21.  Stanton, M. F., et al.  Experimental Pulmonary Carcinogenesis with
     Asbestos.  American Industrial Hygiene Association Journal, 30:236-244,
     1969.

22.  Richards, R. J. and T. G. Morris.   Collagen and Mucopolysaccharide
     Production in Growing Lung Fibroblasts Exposed to Chrysotile Asbestos.
     Life Sciences, 12(II):441-451, 1973.

23.  Brown, R. C.,  et al.  In Vitro Biological Effects of Glass Fibers.
     Journal of Environmental Pathology and Toxicology, 2:1369-1383, 1979.

24.  Wright, G.  Airborne Fibrous Glass Particles.  Archives of Environmental
     Health, 16:175-181, 1968.

25.  Utldjian, H. M. D. and R. T. P. deTreville.  Fibrous Glass Manufacturing
     and Health — Report of an Epidemiological Study, Part I.  Industrial
     Health Foundation Transactions of  the 35th Annual Meeting, 1970.

26.  deTreville, R. T. P.,  et al.  Fibrous Glass Manufacturing and Health —
     Results of a Comprehensive Physiological Study:  Part II.  Industrial
     Health Foundation Transactions of  the 35th Annual Meeting, 1970.

27.  Nasr, N. M., et al.  The Prevalence of Radiographic Abnormalities in the
     Chests of Fiber Glass Workers.  Journal of Occupational Medicine, 13:
     371-376, 1971.

28.  Hill, H. W., et al.  Glass Fibres:  Absence of Pulmonary Hazard in
     Production Workers.  British Journal of Industrial Medicine, 30:174-179,
     1973.
                                     339

-------
29.  Gross, P., et al.  Lungs  of Workers Exposed  to Fiber Glass.  Archives of
     Environmental Health,  23:67-76,  1971.

30.  Champeix, J.  Fiberglass  Pathology and Hygiene of Factories.  Arch
     Maladies Profess.  6:91-94  (1944) (translation).

31.  Roche, L.  The Pulmonary  Hazards in the Glass Fiber Industry.  Arch
     Maladies Profess.  7:27-28  (1946) (translation).

32.  Cirla, P.  Occupational Pathology from Spun  Glass.  Med Lavoro, 39:152-157,
     (1948) (translation).

33.  Mungo, A.  Pathology From Processing Glass Wool Stratified Materials.
     Folia Medica, 43:962-970  (1960)  (translation).

34.  Milby, T. H. and C. R. Wolf.  Respiratory Tract Irritation From Fibrous
     Glass Inhalation.  Journal of Occupational Medicine, 11:409-410 (1969).

35.  Siebert, W. J.  Fiberglass Health Hazard Investigation.  Industrial
     Medicine, 11:6-9,  1942.

36.  Sulzberger, M. B.  and  R.  Baer.   The Effects  of Fiberglas on Animal
     and Human Skin.  Industrial Medicine, 11:482-484, 1942.

37.  Heisel, E. B. and  J. H. Mitchell.  Cutaneous Reaction to Fiberglas,
     Industrial Medicine and Surgery, 26:547-550, 1957.

38.  Heisel, E. B. and  F. E. Hunt.  Further Studies in Cutaneous Reactions
     to Glass Fibers.   Archives of Environmental  Health, 17:705-711, 1968.

39.  Fossick, P. A., et al.  Fibrous  Glass Dermatitis.  American Industrial
     Hygiene Association Journal, pp. 12-15, 1970.

40.  Bayliss, D. L., et al.  Mortality Patterns Among Fibrous Glass Production
     Workers.  Annals of the New York Academy of  Sciences, 271:324-335, 1976.

41.  Konzen, J. L.  Comments on Mortality Patterns Among Fibrous Glass
     Production Workers.  U.S. Department of Commerce, National Technical
     Information Service No. PB-257-784, 1976.

42.  Bayliss, D. L., et al.  Rebuttal to Comments by J. L. Konzen, M. D. on
     the manuscript entitled, Mortality Patterns  Among Fibrous Glass Produc-
     tion Workers.  U.S. Department of Commerce,  National Technical Informa-
     tion Service No. PB-257-784, 1976.

43.  Enterline, P. E. and G. M. Marsh.  Final Report on Part One of Mortality
     Among Man-Made Mineral Fiber Workers in the  United States,  submitted to
     the Medical and Scientific Committee of the  Thermal Insulation Manu-
     facturers Association, 1979.
                                      340

-------
44.  Enterline, P.  E.f Professor and •Chairman,  Department of Blostatistics of
     the University of Pittsburgh,  to J.  W.  Hill,  M.D.,  Medical Director,
     Pilkington Brothers Limited, St. Helens,  England,   (letter dated
     April 9, 1980).

45.  Robinson, C.  F., et al.   Mortality Patterns of Rock and Slag Mineral Wool
     Production Workers,  presented at the National Institute of Occupational
     Safety and Health Symposium in Rockville,  Maryland, 1979.

46.  Morgan, Robert W., et al.  Mortality Study of Owens-Corning Fiberglas
     Production Workers.  Report prepared by SRI,  International for Owens-
     Corning Fiberglas Corporation, 1980.
                                      341

-------
                   DISCUSSION ON MAN-MADE VITREOUS FIBERS

QUESTION   (Dr. Cooper):  You did not mention mesothelioma in your epidemiologic
          studies and I am sure no mesothelioma occured in any of these popu-
          lations.  I would have thought the absence of them would have been
          noteworthy also.

ANSWER     (Dr. Konzen):  The data made no mention of mesothelioma.
                                    342

-------
          THE TRANSLOCATION AND FATE OF SIZED MAN-MADE MINERAL FIBERS
           FOLLOWING EXPOSURE  BY INTRATRACHEAL INSTILLATION IN RATS

                                        by

 David M. Bernstein, Ph.D., Robert T. Drew,  Ph.D., and  Marvin Kuschner, M.D.*
                                Medical Department
                         Brookhaven National Laboratory
                             Upton, New York  11973

                                        and

                                Pathology Department
                              Health Sciences Center
                    State University of New York at Stony Brook
                           Stony Brook, New York  11794
                                     ABSTRACT

    A number of studies have suggested  that both the length and diameter of
    glass fibers are important parameters in determining their deposition  and
    translocation in the lung and in  the subsequent pathological response  by the
    lung.  However, the fibers used in  these previous studies had broad size distri-
    butions and were often administered in a highly artificial manner.  To better
    characterize the biological response to glass fibers, a study is being con-
    ducted to determine the translocation and ultimate fate of fibers of defined
    sizes after introduction into the respiratory tract of rats by both instil-
    lation and inhalation.  The fibers  have geometric mean diameters of 1.5 vim
    (ag = 1.11) and lengths of either 5ym (ag = 1.49) or 60 ym (ag = 3.76).

    Serial sacrifices following intratracheal instillation of either 2 mg  or 20
    mg doses have shown differences in  the response to the two sizes of fibers.
    The short fibers are found primarily within mononuclear phagocytes in  both the
    lung and regional lymph nodes.  The majority of long fibers, however,  cannot
    be totally engulfed by macrophages, nor are they cleared to the regional lymph
    nodes, although smaller fragments accompanying the long fibers may be  so
    cleared.  The long fibers produce a striking foreign body reaction in  the  lung,
    particularly when impacted in the bronchi.

    A "trachea only" inhalation method  was used to expose rats to approximately
    500 fibers/cc for one hour, resulting in the deposition of 30,000 to 50,000
    fibers in the lungs of each rat.  Serial sacrifices at intervals similar to
    those in the instillation study will permit comparison of the biological
    response following these two methods of administration.
*Presented by David  II.  Bernstein,  Ph.D.
                                        343

-------
INTRODUCTION

     The  length  and diameter  of  glass  fibers determine not only their deposi-
tion in the lung !»2  through  inhalation but are also thought to be important
factors in fiber translocation and  subsequent pathological response.3  Stan-
ton and Wrench4  demonstrated  that when placed directly into the pleural
cavity of rats,  glass fibers  are associated with the development of mesothe-
lioma.  It remains unclear whether  glass  fibers actually reach the pleural
cavity when administered  in a less  artificial manner through the tracheo-
bronchial tree.   In the past,  resolving the relationship of fiber size to
these effects  has been compounded by the  difficulty in separating different
lengths of fibers of  the  same diameter.   Using fibers manufactured to
specified size distributions,  this  study  has examined the deposition, translo-
cation, and fate of glass fibers after introduction into the respiratory tract
of rats.

     Three routes of  exposure were  initially considered; intratracheal
instillation of  aqueous suspension, nose  only inhalation exposure, and insuf-
flation of a very thick air suspension of fibers.  The intratracheal instill-
ation provided a means of administering large quantities of fibers into the
lung with relative ease.  Rats are  obligatory nose breathers and when inhaled
through the nose the  majority of the long fibers used in this study were
found to  deposit in the tortuous nasopharyngeal region of the rat.  Hence, a
trachea only inhalation exposure method was developed to expose animals to
fiber aerosols.   With the successful development of the trachea only inhala-
tion methodology, insufflation of very thick air suspensions of fibers was
not pursued further.

     This report reviews  the  methods and  techniques developed for exposure by
intratracheal  instillation, presents the  glass fiber clearance data, and
summarizes the histological findings through six months post exposure.

MATERIALS AND  METHODS

     The  fibers  were  manufactured to either 1.5 x 5ym or 1.5 x 60 urn in size5.
The length distribution of each  group  of  fibers is shown in Figure 1 with the
short fibers having a geometric  mean length of 5.1 urn (SD = 1.49) and the
long fibers a  geometric mean  length of 54 ym (SD = 3.76).  Scanning electron
micrographs of the fibers are shown in Figures 2 and 3.  The fibers were
neutron activated and ZN^5 determined  to  be the best tracer nuclide to allow
quantification of deposition  and clearance of the fibers in vivo.5

Animals

     These studies were conducted with male Fisher 344 rats purchased from
Charles River.   The exposures  were  begun  when the animals were approximately
15 weeks  old.  They were  housed  in  wire cages, allowed food and water ad li-
bitum, and maintained on  a 12  hr light cycle at 22 ± 2°C, 50 percent relative
humidity.
                                      344

-------
CO
4S
Ui
            o
            2
            LJ
            Z>
            O
            LU
                               30   40  50   60   70   80  90
10
                                       FIBER LENGTH (/im)
                       Figure 1.  Length distribution of each group of fibers.

-------
Figure 2.





   347

-------
Figure 3.





    349

-------
Intratracheal Instillation

     The techniques for intratracheal instillation of the glass fibers have
been described earlier5.  Thirty rats per group were instilled with either
1.5 x 60 van  (Group 1) or 1.5 x  5 vim fibers  (Groups 2 and 3) that were tagged
by activation as outlined in Table 1.  Rats in Group 2 were instilled with
approximately the same number of fibers as rats in Group 1 and rats in Group
3 were given the same weight of fiberglass as rats in Group 1.  Since the
fiber concentration administered to each rat was determined by radioassay
immediately  after exposure, only 15 rats could be instilled on any given day.
With this limitation and the necessity to radioassay the groups at the same
time intervals following exposure, the instillation protocol shown in Table 1
was developed.

     In addition, 50 rats/group were exposed to non-activated (or cold) fibers
to insure that potential long term effects were t£e result of the glass fibers
and not the  small amount of radioactivity present.  This number of animals
was chosen from statistical considerations to permit detection of a two
tumor difference between the activated and non-activated exposure groups at the
end of two years.

Necropsy

     The rats were sacrificed by pentabarbital anesthesia with exsanguination
through the  descending aorta.   The lungs were then perfused in situ with
heparinized  isotonic saline through the pulmonary artery, removed, and inflated
with glutaraldehyde vapor using an endotracheal tube (at a pressure of 20 cm
water); and  then infused with glutaraldehyde fixative through the pulmonary
vasculature  (at a pressure of 20 cm water).

     After the lungs were fixed, the hilar lymph nodes, thymus, and adipose
tissue were  dissected away.  In addition, the diaphragm, gastrointestinal
tract, liver, spleen, kidney, brain, and femur were removed for histological
examination.

     Tissues were embedded in parafin, sectioned (at a thickness of 10 urn),
mounted on glass slides, and stained with either hemotoxylin and eosin (H&E),
reticulum, or trichrome stains.  Histoclad mounting media was used for all
sections.

Microscopy

     The standard histological  sections were viewed by light microscopy for
histopathological evaluation and by a pseudo-dark field technique for evaluation
of glass fiber numbers and location in the tissue sections.  In addition,
scanning electron microscopy was performed on fixed tissues prepared by a
critical point drying technique.  The size distributions of the glass fibers
were determined by microscopic  measurement with the aid of a Zeiss MOP-3
image analyzer.
                                     350

-------
    TABLE 1.  FIBER GLASS INSTILLATION SCHEDULE*
Exposure
Group
Group I
Group II
Group III
Group IV
Fiber Size
and Dose
1.5 x 60 ym
20 mg
1.5 x 5 ym
2 mg
1.5 x 5 ym
20 mg
Saline
Control
Number of
Rats Instilled
14
16
14
17
15
15
15
15
Date of
Instillation
2/26/79
2/28/79
3/26/79
3/28/79
3/12/79
3/14/79
4/9/79
4/11/79
*
The instillation schedule was staggered as shown to
permit radioassay of each rat following exposure.
            TABLE 2.  FIBER CONCENTRATION
Exposure
Group
20 mg
1.5 x 60 ym
2 mg
1.5 x 5 ym
20 mg
1.5 x 5 ym
N

21

24

22
Mean

0.15

0.09

0.18
(Standard
Deviation)

(0.04)

(0.04)

(0.02)
      Note:  Fraction Remaining at ~300 days
             after Exposure.
                         351

-------
RESULTS

Animal Weights

     Rats were weighed  in  each group at  equal intervals after exposure.  Since
the time of exposure was offset as  shown in Table 1 and the rats were all of
the same age when received,  the weight curves were shifted reflecting this
temporal offset  in  exposure.   The growth curves  for each group were not signi-
ficantly different  as determined by an F test on the slopes and shown by the
parallel curves  in  Figure  4.

Glass Fiber Clearance

     The clearance  of glass  fibers  from  the rats was determined by in vivo
radioassay of each  apical.   It is important to note, however, that this tech-
nique only accounts for whole  body  clearance of  fibers and is not sensitive to
translocation of fibers within the  rat.

     The clearance  curves  for  each  of the three  exposure groups through  ~300
days are shown in Figures  5, 6,  and 7.   The low  dose short fiber clearance is
significantly different, P < 0.01,  from  either the long or short high dose
group (as determined by analysis of covariance).  This is reflected in the
percent remaining at~300  days as shown  in Table 2.  If the data is evaluated
by a three component exponential model in terms  of short, intermediate, and
long term phases of clearance  (Table 3),  significant differences (P ~ 0.01)
are noted in the short  and intermediate  phases of the two high dose groups.

Scanning Electron Micrographs

     To examine  the pulmonary  response to the two types of fibers by electron
microscopy, rats instilled with 20  mg of either  long or short fibers were
sacrificed two weeks after exposure.  The lungs  of rats exposed to long fibers
are shown in Figures 8  and 9.   Macrophages attempting to phagocytize the long
fibers are readily  noted (Figure 8).  In addition, other areas are seen with
clumps of fibers present  associated with a nodular densely aggregated cellular
response (Figure 9").

     This is  in contrast  with  the response to the short fibers seen in Figures
10 and 11.  These short fibers are found in large numbers in macrophages and
for the most  part are completely engulfed by these cells.  Some fibers are
seen free in  airspaces  (Figure 11).  The nodular aggregates noted with the
long fibers are not evident.

Histological  Results

     The histological results  reported here are from the first serial sacrifice
at six months post exposure involving four animals /group.  In addition, a few
animals died  under anesthesia  for the radioassay procedure.  These animals
were sacrificed as described above and the histological results presented as
well. '
                                    352

-------
                                                     MEAN RAT WEIGHTS
          400
        E 380
u>
g
H
5
          360
          340
                             EXPOSURE GROUP

                             ..111 20mg - I.5x60/tm
                            ___ 20 mg - I.

                            J17I  2mg - I.SxS/tm

                                 SALINE CONTROL
                                                 INSTILLATION DATE
                                                     2/26/79
                                                     2/28/79

                                                      3/12/79
                                                      3/14/79
                                                     3/26/79
                                                     3/28/79
                                                      4/9/79
                                                      4/11/79
          260 K
          240-
                 ..^•".-
                                 i    i
                                               i     i
                                                                    1	I	I
           10   20   30  40   50   60   70  80   90   100  110  120  130  140  ISO  160  170   180
                                         TIME (days) FROM INSTILLATION
                                                                                                       190  200
                                            Figure 4.  Growth curves.

-------
I?
i
                                           1.5  x 60 pm  Expo.6u/z.e

                                                 20 wig I?o4e
        29.1)0   50.00   TS.OO    100-00   IZS.OO   IU-00   115.00   200.00   2».00   290-00   215.00   VD.OO   S2S.U   BO.OO
                      Figure 5.    Clearance curve.



                                        354

-------
£?

fc
                                          7.5  x   5 ]im Expo4ote
                                                 2 mg
 =1)00    n oo    so.oo   li.oo   itm-oo   in-oo   iso-oo    iis.oo    no.m   ns.oo   TSO.DO   ? 15.00   900-00   moo   %o oo
                                       IIM£IDB»Sl
                         Figure  6.   Clearance  curve.


                                          355

-------
&

Is
fc
§*.
    i
                                                x   5 ym Expo-6ote
                                                 20  mg
                         t i

                                * •
                                        I *

                                                  '      '       ..•

*%.00    75-00   50.00    15.00   100.00    IH-OD   IM4B   ITt.OO   1094D   HS-00   HO-OO   7B.OO   900.00   MS.OO   360.00
                                       IM4B   lit.
                                        TinEIDRYSI
                       Figure 7.   Clearance  curve.

                                         356

-------
       TABLE 3.  FIBER GLASS CLEARANCE
                 THREE COMPONENT EXPONENTIAL MODEL

                    Clearance half times (days)
 Exposure      	
  Group        1-10 days    11-60 days    61-300 days

20 mg
1.5 x 60 vm       20            58           173*

2 mg
1.5 x 5 vim
20 mg
1.5 * 5 ym
1A

29
43

63
115

173*
 Not significantly different.  All other half times
 are significantly different from one another
 (P < 0.01).
                          357

-------
Figure 8.





   358

-------
Figure 9.




   359

-------
Figure 10.





    361

-------
Figure 11

-------
      To  illustrate the numbers and locations  of  fibers  and  their  associations
with the histological observations,  photographs  for many of the light field H&E
stained  sections  are accompanied with a dark  field  image of the same field which
highlights  the fibers.  It should also be noted  that with 10 ym sections of the
lung,  it is likely that a 60 ym fiber would be cut  in the sectioning process.
This,  together with the fibers being somewhat randomly  orientated in the lung
may give the appearance that the long fibers  are somewhat shorter than 60 ym.
 1.5  x 60 ym Fibers,  20 mg Exposure
      At  4 days post-exposure a notable cellular response  in association with
 large numbers  of  fibers  was  observed  (Figure  12).   The  initial stages of
 granuloma formation were evident  by 10 days  (Figure 13),  however, no giant
 cells were observed.  Many fibers were seen  either  free in the alveolar space
 or  in association with macrophages.   By 40 days (Figure 14) the granulomas
 were  more defined and giant  cells within these  granulomata were easily seen.

      Microscopic  examination of the 6-month  sacrifice of  four rats/group
 showed that the lungs contained numerous granulomata which were well developed,
 containing epitheloid cells, giant  cells,  and large numbers of fibers (Figure
 15).   These granulomata  were often  peribronchiolar  in orientation  (Figure 16);
 fairly uniformly  distributed throughout the  sections, and sharply demarcated at
 their margins.  Moderate numbers  of fibers occurred singly or in small groups
 outside  the granulomata  (Figure 17) often in  the interstitum, however, rela-
 tively few fibers were seen  within  the alveolar spaces.   Hemosiderin was pre-
 sent  in  association with the fibers.   No 60 ym  fibers were seen in  the lymph
 nodes although occasional smaller fibers or fragments or  larger ones were
 present  (Figure 18).

 1.5 x 5  ym Fibers, 2 mg  Dose

      No  animals in this  group died  prior to the 6-month sacrifice.

      At  6 months,  animals exposed to  2 mg of  the short  fibers revealed a gen-
 erally heterogenous  distribution  of the residual fibers throughout  the pulmonary
 tissue (Figure 19).   There were few or no fibers in most  areas.  Where found,
 the fibers were present  in association with variable sized aggregates of mono-
 nuclear  cells,  small groups  of which  often appeared to  be interstitial (Figure
 20).   There were,  however, some larger fiber-cell aggregates with components
 that  were within  air spaces,  air  spaces now largely obscured by the abundance
 of cells.   The  mononuclear aggregates were not  arranged into structured granu-
 lomata and no  giant  cells were present.   Small  amounts  of hemosiderin were
 found in  association with fiber aggregates.

      Lymph nodes were found  to contain fibers occurring in dense aggregates of
macrophages.  There  was wide interanimal variability in the extent  of lymph
node  involvement and the  size of  lymph nodes within each  exposure group.

 1.5 x  5 ym Fibers, 20 mg  Dose
   %•
      The  lungs  of  the single animal that died at  40 days  post-exposure showed
a similar but more intense response than that described below.

                                       364

-------
Figure 12.





    365

-------
                         Vtvik Field
Figure  13.





     367

-------
Figure 14.




     369

-------
                       '
Figure 15.




    371

-------
Figure 16.





    373

-------
Figure 17.






    375

-------
Figure 18.




    377

-------
                               '"*
                             *     •'•  '    "^
                                                        *  . v*
      *_1 _/ '   '     - ,   ,7  '
          J'. A



•4

                    If A,"
if  -^* ••  '^>
              -
            *-  '

           '+.
           ^
                           ^
                                      V       ' V*
                             Figure 19.


                                 379

-------
Figure 20.




    381

-------
     Microscopic evaluation of the lungs  of  the  animals  from the  6-month  sac-
 rifice  revealed a distinct, usually peribronchiolar  granulomatous reaction  to
 fibers  in some areas,  while in other areas,  fibers occurred  in dense  aggregates
 in association with a  relatively sparse cellular response.   No giant  cells  were
 seen within these granulomata.  Fibers were  clearly  evident  within interstitial
 macrophages (Figure 21) and in some areas could  be seen  in alveolar macrophages
 (Figure 22).   In still other areas, lymphocytes  rather than  histiocytes were
 the predominant cell type seen in relation to the fibers.  Granulomata contain-
 ing dense aggregates of fibers were seen  in  paratracheal lymphoid tissue  (lymph
 sumps)  (Figure 23) .  There appeared to be a  2 to 3 fold  range in  amount of
 residual fiber and associated cellular reaction  in this  exposure  category.  In
 the lymph nodes large  numbers of fibers were seen in dense aggregates associated
 with a  granulomatous response (Figure 24).  Again, there was a large  amount of
 interanimal variability in the extent of  lymph node  involvement and size  of
 lymph nodes.

 DISCUSSION AND CONCLUSIONS

     In both  the 2 and 20 mg dose 1.5 x 5 ym exposure group,  the  fibers
 appeared to lie primarily within mononuclear phagocytes  in both the lung  and
 hilar lymph nodes.  Engulfment of the fibers by  the  macrophages appeared  to
 take place for the majority of fibers within a few days  after exposure.   At
 ~300 days after exposure,  80 to 90 percent of the fibers were cleared from
 the rats in both exposure groups,  with a  low dose (2 mg) short fiber  group
 having  a significantly faster clearance than the high dose (20 mg)  group.

     In contrast,  the  majority of long fibers could  not  be totally engulfed
 by macrophages,  nor were they cleared to  the regional lymph  nodes,  although
 smaller fragments accompanying the long fibers were .so cleared.   The  long
 fibers  produced a striking foreign body reaction, particularly when impacted
 in the  bronchi.

     The whole rat clearance curves for animals  exposed  to the long fiber
 were different from those for the animals exposed to the short fiber  only
 in the  early  stages of clearance (<60 days).   The majority of both types  of
 fibers  were thought to be cleared by way  of  the  mucociliary  escalator,
 however,  short fibers  were also translocated to  the  lymph nodes while long
 fibers  did  not reach the lymph nodes in significant  numbers.   Instead, long
 fibers  appeared  to be  found in foreign body  type granulomas.   While these
 differences were apparent  from the histological  findings the  clearance
 curves were not  sensitive  to fiber translocations within the  rat.

     Aggregation of  the glass  fibers and  the consequent  impaction of  the
 fibers  in the  airways  seems unavoidable with the single  20 mg dose adminis-
 tered.   To circumvent  this,  another group of rats are currently being ex-
posed to much  lower  doses  of sized fibers by intratracheal instillation
repeatedly over  several weeks.   Comparison of the fiber  distribution  in the
lungs from these two studies as well as the  distribution from the inhalation
study will help  evaluate the validity of  these exposures.
                                     382

-------
Figure 21.





    383

-------
Figure 22,





    385

-------
Figure 23.





    387

-------
Figure 24.






    389

-------
     While there are clear differences in the pulmonary response to the diff-
erent size fibers, there is no evidence, thus far, to indicate that either
type of fiber produces fibrosis.  These studies are continuing, however, with
serial sacrifices of four rats/group scheduled at 6-month intervals.

ACKNOWLEDGEMENTS

     The authors wish to thank Mr. Robert Peck, Ms. Mar tine O'Connor, and Ms.
Patricia Carr for the analytical and necropsy work and Mr. Charles Bores for
data management and computer data processing.

     We would also like to thank Dr. Philip Kane for the microscopic evaluation
of the histological slides, and Mr. George Schidlovsky for the scanning electron
microscopy.

     This work is supported by the Thermal Insulation Manufacturers Association
and the United States Department of Energy under Contract No. DE-AC02-76CH00016.

REFERENCES

1.   Harris, R. L., Jr., and V. Timbrell.  The Influence of Fiber Shape in
     Lung Deposition - Mathematical Estimates, In Inhaled Particles IV,
     W. H. Walton, Ed., Pergamon Press, England (1977).

2.   Timbrell, V.  The Inhalation of Fibrous Dusts, Ann. N.Y. Acad. Sci. 132,
     255-273 (1965).

3.   Wright, G. W. and M. Kuschner.  The Influence of Varying Lengths of Glass
     and Asbestos Fibers on Tissue-Response in Guinea Pigs, In Inhaled Particles
     IV, W. H. Walton, Ed., Pergamon Press, England (1977).

4.   Stanton, M. F. and C. Wrench.  Mechanisms of Mesothelioma Induction with
     Asbestos and Fibrous Glass.  J. Nat Cancer Inst.  48:797-821, (1972).

5.   Bernstein, D. M., M. Kuschner, R. T. Drew.  Experimental Approaches for
     Exposure to Sized Glass Fibers, Envir. Health Persp.  34:47-57 (1980).
                                      390

-------
         DISCUSSION ON THE TRANSLOCATION AND FATE OF SIZED MAN-MADE
                                MINERAL FIBERS

QUESTION  (Unidentified):  I am from the Industrial Health Foundation.

          I would like to ask a few questions and make a few comments.

          I was very impressed by the parabolic curve that you showed of
          clearance.  That was about a 300-day curve?
ANSWER
(Dr.  Bernstein):   Yes,  it was.
QUESTION  (Unidentified):  And was it similar in the long fibers as in the
          short fibers?

ANSWER    (Dr. Bernstein):  For the high dose groups it was as if you
          looked at the whole curve together.  If you break it down into
          different clearance regions there were differences between the
          long and short fibers in the early stages and not in the later
          stages.

REMARK    (Unidentified):  The conclusion that I would draw from the
          character of those clearance curves is that the fibers were not
          imprisoned in a very tight manner over the 300-day period.

QUESTION  (Dr. Bernstein):  Which fibers?

ANSWER    (Unidentified):  The long and short.  The short fibers certainly
          were not and the long fibers, according to the character of the
          curve, showed very little residue at the end of 300 days.  The
          clearance was pretty good compared to the curves that one sees in
          intfatracheal injection of silica, for example, where the
          injected silica particles are fairly tightly imprisoned within the
          silicotic nodules.  There is an important difference here and it
          probably reflects the lack of collagenous tissue reaction in the
          nodules.  It reflects the failure of the glass fibers to evoke a
          fibrotic reaction.

REMARK    (Dr. Bernstein):  It is clear from our analysis of the histological
          sections that at six months, there is certainly no fibrotic
          reaction.

QUESTION  (Unidentified):  Did you note a significant difference in the size
          of the granulomas nodule at six months as compared to two weeks?

ANSWER    (Dr. Bernstein):  No, I did not.  I did not do a statistical
          measurement of it.  It is only my own observation.   I did not
          notice it in that time period.  It is our feeling that these are
          not static lesions; that these lesions evolve, new macrophages
          come in, old ones die and that these do evolve in some way  or
          another over a period of time.
                                     391

-------
QUESTION   (Unidentified):  Did you do a similar study of  the  distribution of
           injected  glass  fibers  in the lung  immediately after the  injection?

ANSWER     (Dr. Bernstein):   Oh,  yes.   We looked at  the distribution  in the
           lung immediately after injection,  or  a few hours  after and it is
           much more heterogeneous.

QUESTION   (Unidentified):  It is not  a diffused distribution  of the  fibers, or
           is  it?
ANSWER


QUESTION

ANSWER


QUESTION
ANSWER
QUESTION
ANSWER:
REMARK
REMARK
QUESTION
 (Dr. Bernstein):
 look.
It is really a combination, depending where you
 (Unidentified):  Tou mean  they  are widely  distributed?

 (Dr.  Bernstein):  Well,  it is varying  degrees of  fibers throughout
 many  areas  of  the lung.

 (Unidentified):  What  I  am pointing  to is  the statement that Drs.
 Kuschner  and Wright  made about  the guinea  pigs when  they  indicated
 that  as a result of  intratracheal injection, the  glass fibers were
 deposited in irregular manners,  in heaps,  at the  points of bi-
 furcation of the air passages rather than  a diffused distribution
 of  fibers as one would expect when the materials  are inhaled.

 (Dr.  Bernstein):  Perhaps  I can  answer your question by saying that
 the distribution we  have seen in this  study with  one 20-milligram
 exposure  is different  than what  Wright and Kuschner  saw and it is
 also  different  than  what one might expect  by inhalation.

 (Unidentified):  Would you say  that  the difference between your rat
 results and the guinea pig results in  part result from a
 difference  in dosage?

 (Dr.  Bernstein):  I  would  not like to  compare it  at  this  point.  We
 have  our  rat results for six months  and the guinea pig results which
were  carried out to  the  two year period of the experiment.  At the
 end of two  years I would be better able to compare the two.

 (Unidentified)t  It  seems  to me  that the important result that
 you have  demonstrated  so far is  that,  at least at the six-month
 period, there is no  evidence of  a fibrotic reaction  to the pre-
 sence of  the glass fibers,  but that  there  is a foreign body
 reaction.

 (Dr.  Bernstein):  That is  definitely true  and there  is definitely
a difference in the  reaction of  the  long versus the  short fibers
in this response.

 (Unidentified):  There are  a couple  of interesting findings here.
The glass fiber is a square cut  off  at the end.   Ifc  is not pointy,
in other words, and  yet  that did not prevent the  fibers from
going through the phagocytes.
                          392

-------
ANSWER    (Dr. Bernstein):  Well, I do not know if the fibers went through
          the phagocytes or the phagocytes tried to engulf the fibers.

QUESTION  (Unidentified):  Right.  But the fibers seemed to be continuous
          through the phagocyte?

ANSWER    (Dr. Bernstein):  Yes.

QUESTION  (Unidentified):  All right.   Being cut off square did not prevent
          this process from occurring?

ANSWER    (Dr. Bernstein):  Well, I do not know that a phagocyte knows
          anything about being cut off square or how long the fiber is.

REMARK    (Unidentified):  I know, but this is important in terms of com-
          paring one type of fibrous material and another type.

ANSWER    (Dr. Bernstein):  Well, they are not really square.  The early
          scanning pictures that I showed you in very high magnification
          of the edges showed that they are fairly jagged.   The macrophage
          theoretically may see the end of the particle and say, hey, that
          is a particle I can phagocytize, and then try to do it.  It may
          see the diameter when it comes in head-on perpendicular to the
          fiber and say, yes, I can phagocytize that too.  It does not
          know that it cannot, by the  mechanisms of information that is
          transmitted to the macrophage.  It seems that when you have
          fibers of too large a diameter the macrophage does not try to
          engulf it.  It knows it cannot in a sense.

REMARK    (Unidentified):  You point out also in the abstract that the
          long fibers are found in the pleural cavity but the short
          fibers are not.

ANSWER    (Dr. Bernstein):  I qualified that a little more carefully in my
          talk by saying that this is  a preliminary result.  We have a more
          elaborate study going on now to look at this in detail.  The pre-
          liminary results did Indicate this and the more elaborate results
          will tell us more.

QUESTION  (Unidentified):  Will you be looking for the potential formation
          of mesothelioma?

ANSWER    (Dr. Bernstein):  Yes.  That is one of our end points.

REMARK    (Mr. Ashford):  I am from the Massachusetts Institute of
          Technology.

          I think Dr. Bernstein has been very careful in terms of stating
          the limitations on what conclusions can be drawn from  the  data
          and I would, just as a student of regulatory history,  caution
          you not to take great heart from the fact that the 6 month
          data do not indicate a real problem.  The reason I say this

                                    393

-------
          is, first, there will be some problems relative to the inhala-
          tion characteristics which Dr. Bernstein has found, and second,
          I do not think taking great heart in the science of this point
          is going to do the industry very much good.  It would be very
          good to have alternative technologies in mind, changes in terms
          of the fiber lengths that are produced by the fiberglass indus-
          try and other issues rather than waiting until the data come
          in and then act surprised.  I just think that one has to be
          careful when one views the preliminary results.

ANSWER    (Dr. Bernstein):  I would say that until the results are in
          there is no way I can give an opinion as to what is going to be
          happening.

QUESTION  (Mr. Wright):  I work for the Steel Workers Union in the Safety
          and Health Department.

          I have a technical question.  I know your study did not concern
          this problem but it is an interesting one.  Have you or has
          anyone else looked at the clearance of particles from the
          silicated portion of the bronchial tree?  The reason I am asking
          that is to try to figure if there is any evidence indicating that
          the lung's clearance mechanism for that portion might be less
          efficient for long fibers than it is for shorter fibers or for
          non-fibrous material.

ANSWER    (Dr. Bernstein):  Well, the only thing I can do is to give you a
          comment based on the indirect measurements that we have looked at.
          Those are in terms of whole rat clearance.

          If one looks at the histological results and sees that there are
          a fair number of short fibers going to the lymph nodes, that is
          included in the whole rat measurement.  When one looks at the long
          fiber group and sees that very little is going to the lymph node
          and not that many are going anywhere else, it seems that even
          the silicated mucous transport mechanism is more efficient in
          clearing the long fibers than the short fibers because the
          clearance curves indicate approximately the same quantity left in
          the rat at the end of 300 days.
                                     394

-------
                           OCCUPATIONAL EXPOSURES
                               TO MINERAL WOOL

                                     by

                           Mr. Douglas P. Fowler
                            Center for Community
                               Health Studies
                              SRI International
                            333 Ravenswood Avenue
                            Menlo Park, CA   94025
INTRODUCTION

     The bulk of the work to be presented here was performed  during the period
1976-1978 under Contract Number 210-76-0120 with the National Institute for
Occupational Safety and Health.  In addition to  the work performed for NIOSH,
substantial work has been undertaken in the U.S.  by the Thermal Insulation
Manufacturer's Association (TIMA) and in Europe  by the Joint  European Re-
search Board (J.E.M.R.B.).  This work will be briefly mentioned as well.  The
readers interested in the general questions associated with man-made mineral
fibers in the environment should consult the review prepared  by Corn (1979).

BACKGROUND

     Mineral wool is a generic term that denotes any fibrous  glassy substance
made from minerals (e.g., natural rock) or mineral products (e.g., slag or
glass).  For the purpose of this presentation, mineral wool has been defined
to include only those fibers made from natural rock (rock wool) or from slag
(slag wool), thus fibrous glass is excluded.
                                                       •

     Mineral wool has been produced and used for over a century.  Thoenen
(1939) reported that mineral wool was first produced in Wales in 1840.
Production began shortly thereafter in Germany.   The first U.S. mineral
wool plant began operation in Cleveland, Ohio in 1838.  In 1890, a plant
was in operation in Salem, Virginia.  The first successful commercial
production operation was started in 1897 by C. C. Hall in Alexandria,
Indiana.  The product began to find a substantial market by the end of
the first world war (Pundsack, 1976).  By 1939, there were 71 companies
operating 82 plants manufacturing slag, rock, and glass wool.

     In the late 1930's Corning Glass Works and Owens-Illinois joined  forces
to become Owens-Corning Fiberglas; and the company invested heavily  in
technology to produce glass wool by processes superior to those that had
been used in the past.  The paths of rock wool and glass wool partially


                                      395

-------
diverged at  this point—the  rock wool and  slag wool manufacturers continued
mainly with  the processes  and markets of the past, and the glass wool
manufacturers  opened  new markets,  including textiles  (Smith  , 1976).  How-
ever, the  two  products  continued to  compete in the thermal insulation market.

     The basic process  by  which mineral wool is made  today is similar to that
used in the  1890's.   The raw material  (slag and/or natural rock) is loaded
into a cupola  in alternating layers  with batches of coke and small amounts
of  other raw materials  used  to  give  the fibers special characteristics of
ductility  or size.  The coke is burned, generating high temperatures and
melting the  slag.   The  molten stream of slag issues from a hole in the
bottom of  the  cupola  and is  "fiberized."   Currently,  approximately 70 per-
cent of the  mineral wool sold in the United States is produced from blast
furnace slag.  A small  amount is produced  with natural rock, which is also
usually added  to the  slag  to impart  desired qualities of flexibility to the
fibers.

     In the  past,  the usual  practice was to direct a  stream of steam (or
of  air) to intercept  the falling stream of slag, breaking it into many
small globules which  then  "tailed  out", producing fibers with a semi-
spherical  head.  The  heads broke off as the material  cooled, producing
fibers and "shot"  (the  cooled heads).

     Currently, most  of the  mineral  wool in the United States is made by
variations of  the  Downey process.  The stream of molten slag or rock falls
onto a spinning rotor and  the partially fiberized slag or rock is further
attenuated by  an annular stream of steam or air.  The "dry spinning" process
is  used by a minor fraction  of  the producers.  This is a mechanical
attenuation  process that does not  use fluid attenuation for additional
separation.

     As the  fiber  is  formed, it may  be further treated to increase its
utility for  one or more of its  intended uses.  In general, these treatments
are applied  immediately following  the rotor, by the atomization of liquids
that are "sprayed" onto the  newly  formed fibers.  In  almost all cases, an
oil will be  applied in  this  manner to reduce the "dustiness" (tendency to
become airborne) of the bulk products.

     Where the mineral  wool  product  to be  produced is required to have
moderate or  substantial structural rigidity or stability (as in equipment
insulation and building insulation batts and blankers), a "binder" (usually
a phenol formaldehyde resin) may be  added  immediately following or in place
of  the oil treatment.   The mineral wool may then be compressed into "batts",
"blankets" or  "boards"  or  left  loose as "wood".

     Those products that are to be used without additional covering (such as
high-density equipment  insulation  and some residential insulation batts)
are packed for shipment.   Other products require further covering, for
example, residential  structural insulation is often covered with a vapor
barrier (e.g., Kraft  paper treated with asphalt or aluminum foil) on one
side and untreated paper on  the other side.  For industrial insulation (e.g.,
boilers),  a wire mesh covering  is  often added.

                                     396

-------
MINERAL WOOL USE

     Mineral wool is widely used in structural and industrial  insulation pro-
ducts, as well as in cements, mortars,  ceiling tiles,  and  other  products
where its characteristics of thermal and structural stability  are desirable.
The products in which mineral wool is used include:

     •    "Blowing" wool and "pouring"  wool,  loose bagged  wool (either  granu-
          lated or not) that can be blown by  pneumatic blowers or poured by
          hand into residential or commercial building structural spaces.

     •    Batts and blankets, relatively loose and light  (low  density)  material
          shaped to file between structural members of residential or commercial
          buildings.

     •    Cement, mortar, or ceiling tile. Producers  of  these1 products add
          bulk fiber to their product to impart structural strength and
          qualities of fire resistance  and thermal and sound insulation.

     •    Industrial and commercial insulation products for covering pipes,
          ducts, boilers and other equipment.  High density material with
          significant amounts of binder added.

     •    "Fireproofing" to be sprayed  upon steel girders  in buildings.

     •    Miscellaneous small volume uses; in friction materials, reinforced
          plastics, etc.

     Transportation costs are a significant fraction of the costs of insulation
products; to reduce these costs, the industry has become  highly  regionalized.
The most directly competitive product is fibrous glass.

     In some areas of the U.S., mineral wool  is the predominant  mineral fiber
insulation material, while in others fibrous  glass predominates.  Because of
its greater density, mineral wool is a  more effective sound insulator than
fibrous glass, and is thus often specified in industrial  applications.   However,
this greater density can be a drawback in the insulation  of residential and
commercial structures, particularly where framing is light and the required
thermal insulation effectiveness is high.

     Fibrous glass has steadily increased its share of the total insulation
market over the past 30 years.  If the  insulation market  is examined in de-
tail, it can be seen that the most probable future market for mineral wool
is in the industrial sector, with relatively  limited usage in residential and
commercial products.  In general, the residential and commercial market frac-
tion for mineral wool is continuing to decline, with strength only in those
regions where it has marked economic advantages over fibrous  glass.  This
trend is expected to continue, with mineral wool consolidating  its position
in the industrial market and gradually  relinquishing part of  its present
share of the commercial and residential insulation market.  It may be expected
that mineral wool will find increasing  use as a substitute for asbestos, as
asbestos is "phased out" of some industrial products because of  its known

                                      397

-------
 adverse health effects.   Thus,  it may be expected  that  those workers who have
 been exposed to asbestos in the past  may in the  future  be  exposed to mineral
 wool fibers.

 HEALTH EFFECTS OF MINERAL FIBER EXPOSURE

      The health effects  attributable  to mineral  fibers  have been the subject
 of major international conferences in the past 10  years (New York, 1964;
 Dresden, 1968; Lyon,  1972).  Other conferences such  as  the Johannesburg con-
 ference in 1969 and the  ILO Helsinki  conference  in 1971 have also devoted
 substantial portions  of  time to the same and associated topics.

      The majority of  these reports, however, deal  with  only one category of
 mineral fibers, asbestos.   [We  will set aside, for the  moment, Harington's
 (1975) objection to the  use of  "mineral fiber" as  a  generic term to include
 the amorphous man-made fibers.]  Little attention  has been paid to the health
 effects of other mineral fibers with  the exception of limited work on fibrous
 glass.

 Health Effects of Asbestos

 Cancer—
      The most serious potential consequence of mineral  fiber exposure is the
 development of cancer.   An increased  incidence of  the following tumors has
 been associated with  human exposure to asbestos:


        	Tumor	             Selected Epidemiologic Evidence

        Lung Cancer                       (Doll,  1955; Knox, 1968; Selikoff,
                                          1973)
        Mesothelioma                      (Bohlig,  1973;  Newhouse, 1973)
         (Pleural & Peritoneal)
        G.I.  Cancer                       (Selikoff,  1973)
        Laryngeal Cancer                   (Stell, 1973;  Newhouse and Berry,
                                          1973)


 Fibrotic Lung Disease (Asbestosis)—
      There is no need for  further documentation  of asbestosis in humans; such
 documentation exists  in  scores  of studies.   Although the attack rates have
 varied from study to  study (and for type of asbestos fiber), it is clear
 that  inhalation of any form of  asbestos will, given  sufficient doses, lead
 inevitably to asbestosis in a significant fraction of the  exposed population.
 The universality of the  response can  be seen in  the  table  on pages 364-365
 of Harington's  (1975) review.

Health  Effects  of Fibrous  Glass

   % The  only exposure-specific population studies that  have been carried out
 on the  consequences of exposure to mineral fiber other  than asbestos have
been on fibrous  glass.  The studies (Wright,  1968; Nasr, 1971; Utidjian, 1970;

                                       398

-------
Gross, 1971) did not address the question of malignancy.   They concluded from
pulmonary function (Utidjian), radiographic (Wright and Nasr), and post-
mortem (Gross) studies that there were no significant effects  from occupational
exposure to fibrous glass.   A discussion of these studies  was  presented in
an article by Dement (1975).  A study by Enterline (1975)  examined the mortal-
ity experience of a cohort of 416 men who retired during the period 1945-
1972 from six fibrous-glass manufacturing plants.  Enterline found "no evi-
dence of an excess in respiratory cancer mortality.   No mesotheliomas were
noted."  For 115 of the men, the stated retirement cause was disability.  Com-
paring this with the expected distribution, Enterline found "...no evidence
of any unusual health hazards, with the exception of a possible excess in
chronic bronchitis."

     These and other studies were reviewed in-depth in the preparation of the
NIOSH Criteria Document on Fibrous Glass (NIOSH,  1977). Upon  consideration
of human health studies and animal tests, NIOSH concluded  that two categories
of fibrous glass could be defined—those fibers larger than 3.5 micrometers
(ym) diameter and those less than 3.5 ym.  For the former, it  was concluded:

          The primary health effects associated with the larger diameter
          fibers involve skin, eye, and upper respiratory  tract irritation,
          a relatively low incidence of .fibrotic (lung) changes, and
          preliminary indication of a slight excess mortality  risk due to
          non-malignant respiratory diseases.  In this regard, NIOSH
          considers the health hazard potential of fibrous glass to be
          greater than that of nuisance dust, but less than that of coal
          dust or quartz.

     The Criteria Document goes on to address the potential problems asso-
ciated with small diameter fibers.  The laboratory animal  implantation studies
of Stanton (1972, 1977) were examined and it was concluded that these results
could not be extrapolated directly to conditions of human exposure.  The
document continued:

          On the basis of currently available information, NIOSH does not
          consider fibrous glass to be a substance that produces cancers as
          a result of occupational exposure.  However, these smaller fibers
          can penetrate more deeply into the lungs than larger fibers and
          until more definitive information is available,  the possibility
          of potentially hazardous effects warrants special consideration.

     On the basis of these considerations, NIOSH recommended an environmental
(workplace air) concentration limit of 3 fibers/cm3, determined as a  time-
weighted average concentration for up to a 10-hour work shift in a 40-hour
work week.  Only those fibers with a diameter less than or  equal to  3.5 ym
and a length equal to or greater than 10 ym are covered by  the recommended
limit.  Additional recommendations involve medical examinations and  record
keeping.
                                     399

-------
 Health Effects of Mineral Wool

      It has been assumed previously that fibrous glass and rock (or slag)
 wool could be appropriately grouped together in a discussion of the health
 effects of mineral fibers..  No reported studies of those exposed only to
 rock wool or slag wool are known, although Enterline is currently carrying
 out such a study, sponsored by the Thermal Insulation Manufacturers Associa-
 tion (TIMA), (Konzen, 1980), as is NIOSH (Ness, 1979).  No firm evidence
 exists from which the health effects of rock wool or slag wool can be pre-
 dicted.  The evidence most clearly indicating potential exposure risks asso-
 ciated with mineral wool is the work of Stanton et al. {1972, 1977), Kuschner
 and Wright (1976), Pott et al. (1976) and Davis (1972).  In these laboratory
 studies, it has been found that long (& 10 ym) , thin (4, 1 ym) fibers have
 greater biological potency (tumorigenicity, fibrogenicity) than shorter or
 thicker fibers, regardless of the chemical composition of the fibers.  This
 indicates that these long, thin fibers are probably of greatest concern in
 human exposures to mineral wool.  Figure 1 is an adaption of some of Stanton's
 data, showing the effect of increasing the fraction of long, thin fibers in
 implanted fibers on the probability of tumor response in animals (Stanton, 1977)

 Comparability of Results for Other Fibers:  Extrapolation to Mineral Wool

      There is convincing epidemiological and case report evidence that asbes-
 tos, upon inhalation, is fibrogenic and carcinogenic in man.  Fortunately,
 no such convincing human evidence exists for other mineral fibers.  It is
 difficult to extrapolate from the results for asbestos to predict human health
 effects from exposure to mineral wool.  The work that has been done with
 fibrous glass is more directly applicable, but there are still many areas  of
 uncertainty.  The NIOSH decision (in regard to the recommended environmental
 standard for fibrous glass) that "...until more information is available,
 the recommended standard can also be applied to other man-made mineral
 fibers..." seems appropriate with respect to mineral wool.  The two recent
 NIOSH publications (1976, 1977) dealing with fibrous glass are recommended
 as background reading on the health effects of mineral wool, as are the
 Copenhagen Workshop Proceedings (JEMRB, 1977).

      One aspect of the potential problem associated with the human exposure
 to this material has been a suggested demand for small fiber diameter.
 Figure 2 shows the effect on bulk thermal conductivity (the inverse of insu-
 lation effectiveness) of fiber diameter in these products.  Because of the
 costs associated with attaining smaller fiber diameters, most U.S. commercial
 products, particularly those used in home insulation, have a median fiber
 diameter near 4-5 ym.  In Europe, however, and particularly in the Soviet
 Union,  mineral wool fibers are being commercially produced with median fiber
 diameters 
-------
   i.o
   0.8
I
   0.6
£ 0.4
  0.2
                                   PARTICLE SIZE RANGE (UM)
                                     0.25 < DIAMETER < 1.6
                                        LENGTH > 64
                 10
20
30          40           50
     Percent of Total Weight
                                                                            60
70
80
      Figure  1.   Probability of  tumor versus  percent of  implanted  particles  in size range.*
      *Adapted  from Stanton, 1977.

-------
o
ro
               	I

             0         1



           SOURCE: Pundnck. 191*6
_L
I
I
456


   FIBER DIAMETER. Mf"
                           Figure 2.   Thermal conductivity as a function of  fiber diameter.
                                                 10

-------
o
u>

30
z
„ M

" 	 -PI



B.
BULK SAMPLE G-1 (19431












N • 187
30 	 : 	
5
111
n TO 	 . .
K
a. •


	

r




BULK SAMPLE G-2 (19431


1
: 	 j H


w
O.






40
w
U
	
30 	
a.


1 1 1 1 1







— — •

N - 101 H "
z
Ul
5
a i





1 1 i — •
BULK SAMPLE G-3 (1946)


=r


ni






JLK SI
N - 103 K
S M *
oc
10 •



-- o


• B
^•^
II K SAMPIF G-5 110771 	 T - ~ —
N 5/1


ULK S

" BULK S
-n


kURI £ ^_« (tut)) ... 5
N • 1IB g M
c ~
. • • a.
• M











0.4 0.6 1.0




Z
UJ
r» nn

^— 
: -,t
MPUE U-B (193(1 "!" •"" '" "- '"
N • I2t ; .f.


-H I-
III 1 1 1 I I M 1 1
. 1
~~1 	 1 1
Mill 1 1
2.0 6.0 tO.O 20.0 30.0 0.4 0.6 1.0 2.0 60 10.0 20.0 30.0
FIBER DIAMETER £m FIBER DIAMETER «rn
           Figure 3.  Frequency of occurrence of  fibers  of  specific  diameter in mineral wool samples.

-------
 shown are not asbestos.   Admixture of asbestos with other  insulation materials
 was apparently practiced from time to time in the past.  In addition,  the
 producers and users of mineral wool products  also commonly produced and used
 asbestos-containing products, and exposures were mixed.  Asbestos  exposure
 is thus a confounding variable in assessment  of  health effects  due to  expo-
 sures to mineral wool in the past.

 PRIOR STUDIES OF OCCUPATIONAL EXPOSURES

      Human exposures to  mineral wool fibers have been examined  only in a few
 studies.  In the first of these, by Carpenter and Spolyar  (1945),  dust con-
 centrations in a mineral wool production plant were measured by Greenburg-
 Smith impingers in 1934.  The dust counts so  measured ranged from  12-26
 million particles per cubic foot (mppcf)  with limited dust control equipment
 installed.  When more effective controls had  been installed, a  resurvey by the
 same investigators found dust concentrations  of  5-10 mppcf.

      In 1962, Sheinbaum  reported the preliminary results of surveys in the
 building trades, including the application of "asbestos-rockwool cement" as
 a fireproofing and sound insulation agent. He found "extremely dusty  con-
 ditions," with average breathing zone impinger dust counts "about  200  mppcf."

      Both of the above studies share a major  disadvantage—the  method  of meas-
 urement does not differentiate between mineral wool fibers and  general partic-
 ulate material.  Thus, it is difficult to ascertain how much of the inhalation
 burden imposed upon the  workers in these operations resulted from  mineral wool
 fibers and how much resulted from other material.   Total particulate mass
 concentrations and fiber size were not determined in the above  studies.

      In 1976, Corn et al. published the results  of extensive industrial hygiene
 surveys in two mineral wool production plants.   With the use of personal samp-
 ling pumps, measurements were made of total suspended particulate  matter con-
 centrations and of fiber concentrations.   The latter analysis was  performed
 with optical and electron microscopy, and the sizes of the fibers  observed
 were determined.

      In Plant A,  ceiling and wall panels  and  tiles containing about 50 percent
 fiber were produced.   Optically visible (>, 1  ym  diameter)  total fiber  concen-
 tration ranges were 0.2-1.4 fibers/cm3;  electron microscopically visible
 (£, 1 vim diameter)  total  fiber concentrations  ranged from 0.0056-0.16 fibers/cm3.
 Total suspended particulate material levels were 0.53-23.64 mg/m3.

      In Plant B, where specialized thermal insulation materials were produced,
 total suspended particulate matter levels were 0.045-6.88  mg/m3.   Fibers
£, 1  vim (diameter)  were found in concentrations from 0.11-0.43 fibers/cm3-
 The  concentrations of those fibers less  than  1 ym diameter were 0.0059-0.089
 fibers/cm3.

      In both plants,  the fraction of respirable  fibers (less than  3 ym dia-
 meter)  was  approximately 75 percent.   The total  airborne dust concentration
 (mg/m3)  was found  to  be  a poor indicator  of airborne fiber (fibers/cm3)
 concentration.

                                     404

-------
     Esmen, et al. (1978) recently presented data upon the occupational expo-
sures In five mineral wool plants, including the two (mentioned above)  dis-
cussed by Corn, et al. in 1976.   Their general findings were that "the  results
of the study indicate that the average exposure is about 0.1 to 0.5 fibers/ml.
The results also indicate that despite operational diversities  among the
plants the size and length distributions of airborne fibers were consistent.
It was also found that there is an excellent correlation between average total
suspended particulate matter and average fiber exposure for types of work
activity found in the plants..."  Although the last statement may appear to
conflict with their conclusion in the previous study,  it should be noted that
they refer to excellent correlations of average concentrations  as opposed to
poor correlations of individual (matched) concentrations in the previous work.

     Recent European studies were discussed at a workshop in Copenhagen (JEMRB,
1976).  It was stated in the discussion of those studies that "...concentrations
of fibers in the respirable range encountered in the production industry vary
between averages of about 0.03 and 0.2 fibers/ml" (Hill, 1977).

     Schneider, in discussion of the mineral wool user industries in Scandi-
navia (1979), found that home insulation installers and industrial insulation
installers had the highest exposures among the user groups, with a few expo-
sures over 1 f/cm3.  He found that optical microscopy was adequate for  defini-
tion of exposure, which ranged from 0.05 to 3 fibers/cm3.

     The National Institute for Occupational Safety and Health has engaged in
several studies that are now being presented.  This report presents one such
study, and a NIOSH report on one ceiling title productions plant has recently
been presented, with information on an epidemiologic study of the workers at
that plant (Ness, 1979; Robinson, 1980).

     In the investigation reported here, five production sites and six user
sites of mineral wool were selected for study, based upon the representative-
ness of the operations and the conditions of exposure of the workers in those
sites.  Study methods included breathing-zone air sampling for airborne partic-
ulate material (total, fibrous,  and respirable) with analyses to determine total
and respirable airborne particulate levels (gravimetric); airborne fiber con-
centrations and fiber size distributions (optical and scanning electron micro-
scopy); and airborne trace metals (atomic absorption).  Limited evaluations
of worker exposure to carbon monoxide, heat, noise, and miscellaneous other
materials were performed in some site surveys.  In addition to the environ-
mental evaluation, samples of bulk materials being produced and used were taken
for analysis.  Analysis included optical microscopic determinations of fiber
diameter, determination of bulk sample elemental content by atomic absorption
(AA) and x-ray florescence (XRF), elemental analyses of  separated  fibrous and
compact particles by AA and XRF, and elemental analyses  of  individual  particles
by x-ray microprobe.

     In Tables 1 and 2, we show the general characteristics  of  the facilities
examined.
                                     405

-------
                                 TABLE 1.  MINERAL WOOL PRODUCTION  PLANTS  SURVEYED


Raw materials
Years of production
Fiber- forming
process
Fiber
description
Products
produced
Worker
population
(Fiber production
and Maintenance)
Potential
exposures
Plants
A
Steel mill slag.
lead smelter slag
Coke, oil, PF rusln.
asphalt
28
Centrifugal
spinner with
steam attenuation
Slag wool
Bates, blowing
wool , and pouring
wool
100
Fibers, lead
fume. H2S,
PF resin, noise
B
Steel mill slag,
Iron ore, "phos-
phate" slag, coke,
PF resin, oil,
asphalt
29
Centrifugal
spinner with
steam attenuation
Slag wool
Batts, blowing
wool, pouring
wool, baled
wool
80
Fibers, combustion
products, HjS, CO,
PF resin, noise
C
Steel mill slag
rock
coke
maleic acid, oil
6
Dry spinner
(Powell process)
Slag wool
Blowing wool.
Baled wool
45
Fibers, combustion
products, metal fume,
maleic acid, noise
D
Iron smelter slag,
dolomite, quart zlte,
coke, oil
20
Centrifugal spinner
with steam attenuation
Slag wool
Calling tile
15
Fibers. CO,
combustion products
noise, general dust
E
Steel mill slag,
dolomite, PF resin,
coke, oil
50
Centrifugal spinner
with air attenuation
Slag wool
Industrial insulation .
blocks, blankets,
pipe covering
30
Fibers, noise
o
cr>

-------
                        TABLE 2.  MINERAL WOOL USER FACILITIES  SURVEYED
Facility
Product
usedj
|
Application
Processes
Worker
population
Years of
use
Potential
exposures
Bloving wool.
(Slag wool)
New house Insul-
ation
Blowing
4-10
15
Fibers, heat, CO
Blowing wool
(Slag wool)
Addition to
existing Insula-
tion
Blowing
4-10
45
Fibers, heat, CO,
settled house dust.
Industrial
blankets
(Slag wool)
Fabrication for
shipment
Facing with wire
•eah, packing
20
SO
Fibers
Bulk (slag wool)
wool
Production of
celling tiles
Mixing wool with
slurry, baking,
cutting, sanding,
painting, packing
tiles.
60
20
Fibers, clay, paint,
noise. •
Fireprooflng
Spray application
of fibrous fire-
proofing to
structural steel.
Pneumatic blowing
of dry fibrous mix,
wetted with spray
nozzle as applied.
2
10
Fibers, dust
Industrial blankets
Boiler Insulation
Facing with wire
mesh, application
of cement.
3
15
Fibers, dust,
noise

-------
      Although the original report to NIOSH (Fowler,  1978)  should be examined
 for details, we will consider here a few of the points of  interest  in respect
 to comparisons with asbestos, and present a summary  of the findings.

      Figure 4 is a presentation of the 95 percent confidence limits of the
 geometric means of exposures to fibers, total particulate  material, and
 respirable particulate material in the producer and  user facilities surveyed.
 Also presented there is a comparison of the fiber sizes found in the eleven
 facilities, by opt cal microscopy.

      Figure 5 compares the fiber concentration found by optical  microscopy,
 with those found by scanning electron microscopy.  As can  be seen in those
 two figures, the production workers had substantially lower exposure to all
 forms of airborne particulate material than did the  user workers.

      Further, the user workers' exposure was to smaller fibers than was the
 production workers' exposure.  The difference in length can be seen in the
 lower section of Figure 4, where the sizes of the fibers observed with the
 optical microscope are shown.  The difference in diameter  of fibers to which
 they are exposed between production workers and users is apparently slight.
 However, as shown in Figure 5, examination of the samples  with the  scanning
 electron microscope reveals substantially more fibers than does  optical micro-
 scopy.   The mean concentration by electron microscopy in the 12  samples for
 which both types of microscopy was applied is nearly four  times  the mean
 determined by optical microscopy.

      The phenomenon is not universal,  however, and two examples  are illus-
 trative of the differences in exposure which may appear among users of mineral
 wool.   The first is the installation of "blowing wool" in  attics.   In this
 job,  two workers are usually employed.   One of them  opens  bags of compressed
 wool  and empties the bags into a hopper from whence  the wool is  pneumatically
 conveyed through a hose into the space to be insulated.  The second worker
 directs the blown wool into the space (usually an attic) to ensure  adequate
 depth and uniformity of coverage.

      In the second example, the installation of sprayed fireproofing,  two
 workers are also employed.   The first  empties bagged fireproofing material
 (a mixture of mineral wool, cement,  and proprietary  materials) into a hopper/
 blower  very similar to the device  used for the installation of the  blowing
 wool.   The mixture is also pneumatically conveyed to the second  worker via
 hose.   At  the point of exit from the hose,  however,  the blown cement  mixture
 is wetted  by a water spray, and the  wetted mixture is directed onto beams and
 other structural members,  to which it  adheres.

     The  exposures within the two  trades are shown in Table 3.

     It  is  evident that  the exposures  are different.   The  blowing wool instal-
 lers are exposed to substantially  more  small airborne particulate material
of all  sorts  than the sprayed fireproofing installers,  even though  the latter
are exposed to higher total airborne particulate material.
                                     408

-------
 FIBER
 CONCENTRATIONS
 (f/cc)
 (optical microscopy)
                  PRODUCERS
                    USERS
IMHI
 TOTAL
 PARTICULATE
 lm«/m3)
                  PRODUCERS
                    USERS
 RESPIRABLE
 PARTICULATE
 (mg/m3)
                  PRODUCERS
                    USERS
                           0.1
                           1.0
                                                     f/cc or mg/m
                                                   FIBER SIZE bint)
                  1.0
                  10
2.0

AIRBORNE
FIBER
DIAMETER


AIRBORNE
FIBER
LENGTH

PRODUCERS



USERS
PRODUCERS



USERS
I

%

•
1



mti
                                                                                       20
Figure 4.   Comparison of  exposures of  production and user  facility workers.
                                          409

-------
PRODUCTION WORKERS
    42 SAMPLES
                    SEM
                    OM
   USER WORKERS
     12 SAMPLES
                    SEM
                    OM
                                                      I
                       0.1
0.2
  0.6
f/ce
1.0
2.0
    Figure 5.   Comparison of confidence  limits  on geometric mean fiber
                concentrations for samples  examined by scanning electron
                microscopy (SEM) and optical microscopy (OM).
                                     410

-------
TABLE 3.  COMPARISON OF MEAN EXPOSURES FOR SPRAYED FIREPROOFING
          AND BLOWN INSULATION

Fibers/cc (O.M.)
Fiber s/cc (SEM)
Fiber Diameter (O.M.)
Fiber Length (O.M.)
Tot. Susp. Part. Matl.
Respirable Part. Matl.
Sprayed
Fireproofine
0.384 f/cc
0.217 f/cc
2.4 ym
35.3 ym
o
7.461 mg/m
0.370
Blown
Insulation
0.240 f/cc
3.09 f/cc
1.6 ym
12.0 ym
2.657 mg/m3
2.565 mg/m3
                              411

-------
      Our general conclusions were that the production workers surveyed were
 found to have relatively low exposures to all forms of airborne particulate
 material, with few exceptions.  The user workers had higher but more variable
 exposures.  It was generally not possible to separate exposure categories
 on the basis of different exposures; there was significant overlap of the  con-
 fidence limits on mean exposure across the facilities surveyed.

      Past exposures in this industry were probably higher than at  present,  and
 asbestos exposure was relatively common.

      In addition to exposures to airborne particulate material, exposures  to
 excessive noise levels were universal in the cupola areas of the production
 plants.  Heat stress was a potential problem for the installers of blown mineral
 wool insulation.

      Exposures to small diameter (<1.0 ym) fibers were not common, except  in
 the installation of blowing wool.   In close installation situations,  electron
 microscopically visible airborne fibers were present in concentrations up  to
 ten times greater than optically visible fibers.

      SRI's recommendations were that:

      •    The exposures of blowing wool installers to small fibers should  be
           evaluated further.

      •    The noise exposures of cupola operators should be evaluated,  and
           engineering solutions to this problem should be sought.

      •    The exposure of sprayed  fireproofing workers to total airborne
           particulate material are excessive,  and suitable personal respira-
           tory protection should be sought.

      •    Engineering measures to  ameliorate the working conditions of the
           blowing wool insulation  installers should be sought for  both the
           worker in the attic,  and the worker emptying bags into the hopper
           (in the truck).

      •    Additional old samples should be sought to clearly identify
           potential past  exposures to small diameter fibers.

COMPARISON TO ASBESTOS EXPOSURES

      Only  two  cases are known where mineral wool has been directly substi-
tuted  for  asbestos,  and the potential occupational exposures subsequently
measured.

     Reitze, et al.  (1972)  evaluated the exposures of sprayed fireproofing
installers to airborne asbestos  fibers.   The material and process  used was
similar to that used  in the installation described above,  except that the
spray mixture contained substantial  quantities of asbestos.   The worker
emptying bags into  the hopper was  exposed to concentrations of asbestos


                                     412

-------
fibers ranging from 5-22 fibers/cc (optical microscopically visible fibers
> 5 ym), and the nozzle operator was exposed to concentrations between 30-100
fibers/cc.  These concentrations were more than 100 times greater than the
concentrations found in our study of the workers using a mineral wool based
mixture.

     Balzer, et al., (1972) investigated the dust-producing potential of five
different thermal Insulation materials.  Of these, one contained ~65 percent
asbestos, while another was comprised principally of mineral wool, and was
intended as a substitute for the first.  The materials were treated by installa-
tion methods common in the field, but in a controlled environment.  Fiber
counts and total dust were measured during each of several operations, includ-
ing hand sawing, scoring with a circular saw, band sawing, simulation of
application, simulation of pounding the. insulation into place, and a simula-
tion of tearout of old insulation.

     The results are shown in Table 4.

     The potential exposures to fibers from the product containing mineral
wool are substantially (10-40 times) lower than from the asbestos-containing
product.  Total particulate material exposures varied.  In some cases, the
exposure was higher, and in some cases lower, for the mineral wool product as
compared to the asbestos product.

     From these two cases, it seems reasonable to tentatively conclude that
total exposure to fibrous particulate material can be reduced by the substi-
tution of mineral wool for asbestos in some products.  Each case must be judged
individually, however, and the suitability of any proposed substitute must be
carefully guaged.  Asbestos has been used in many widely-variant products
because of its unique physical characteristics.  The wholesale-enforced sub-
stitution of mineral wool (or any other material) for asbestos may have serious
economic and technical repercussions.  The entire life-cycle of each product
containing asbestos must be investigated before a decision to substitute is
made.  The most suitable substitution must then be selected, based upon the
uses and available production technology for the specific product under
consideration.

REFERENCES

Balzer, J.,  et al.  1972,   Dust-producing potential of construction materials.
     Safety and health in shipbuilding and ship repairing.  International
     Labour Office,  Geneva, Switzerland.

Bohlig, H.,  and E.  Rain.   1973.  Cancer in relation to environmental exposure.
     Biological Effects of Asbestos.  Proceedings of the Working Conference
     held at the International Agency for Research on Cancer, Lyon, France,
     2-6 October 1972, edited by P. Bogovski et al., World Health Organization,
     International  Agency for Research on Cancer, IARC Scientific Publications,
     8i207-221 Lyon.

Carpenter, J.  L., and L.  W. Spolyar.  1945.  Negative chest findings in a
     mineral wool industry.  Indiana Medical Journal.

                                      413

-------
 TABLE 4.  COMPAIRSON OF ASBESTOS AND MINERAL WOOL CONTAINING
           INSULATION, AVERAGE DUST GENERATION
           (Source:  Balzer, et al., 1972)

OPERATION
Hand Sawing
Band Sawing
Scoring
Application
Pounding
Tearout
Total Particulate
Material (mg/m3)
A
12.6
89.8
159.8
7.9
2.3
26.4
B
3.9
58.6
345.8
3.1
3.4
62.9
Fiber Count
(F/cc)
A
57.3
376.2
2629.7
74.2
—
268.4
B
1.7
23.1
63.2
0.9
—
26.6
A - Asbestos
B - Mineral Wool
                               414

-------
Corn, M., et al.  1976.  Employee exposure to airborne  fiber  and  total  particu-
     late matter in two mineral wool facilities.   Envir. Research.   12:59-74.

Corn, M. 1979.  An overview of inorganic man-made fibers in man's environment.
     Dusts and disease.  Pathotox Publishers, Inc.,  Park Forest South,  111.

Davis, J. M. G.  1972.  The fibrogenic effects of mineral  dusts injected into
     the pleural cavity of mice.  Br. J. Exp. Pathol.   53:190-2011.

Dement, J. M.  1975.  Environmental aspects of fibrous  glass  production and
     utilization.  Environment Research 9.  295-312.

Doll, R.  1955.  Mortality from lung cancer in asbestos workers.   Br. J. Ind.
     Med.  12:81-86.

Enterline, P. E., and V. Hendersen.  1975.  The health  of  retired fibrous glass
     workers.  Arch. Environ. Health.  30:113-116.

Esmen, N., et al. 1978.  Exposure of employees to man-made mineral fibers:
     Mineral wool production.  Environmental Research.  15: 2,  262-277.

Fowler, D. 1978.  Industrial hygiene surveys of occupational  exposures  to
     mineral wool.  Final Report on Contract 210-76-0120  (NIOSH).  Cincinnati,
     OH.

Gross, P., J. Turaa, and R. T. P. de Treville.  1971. Lungs of  workers  exposed
     to fiber glass:  A study of their pathologic changes  and their dust content.
     Arch. Environ. Health.  23:67-76.

Harington, J. S., A. C. Allison, and D. V. Badami.  1975.   Mineral fibers:
     Chemical, physicochemical, and biological properties.  Advances in Pharma-
     cology and Chemotherapy.  12:291-402.

Hill, J. W.  1977.  Health aspects of man-made mineral  fibers.  A review.
     Ann. Occup. Hyg.  20:161.

JEMRB.  1977.  The biological effects of man-made mineral fibers  (MMMF).
     Proceedings of a Workshop.  Ann. Occup. Hyg.  20:149.

Knox, J. F., et al.  1968.  Mortality from lung cancer  and other causes among
     workers in an asbestos textile factory.  Br. J. Ind.  Med.   25:293-303.

Konzen, J. 1980.  Health aspects of man-made vitreous fibers.  This Conference.

Kuschner, M., and G. W. Wright.  1976.  The effects of  intratracheal instilla-
     tion of glass fiber of varying size in guinea pigs,  in Occupational Expo-
     sure to Fibrous Glass.  Proceedings of a Symposium.   HEW Publication No.
     (NIOSH) 76-151.  U. S. Dept. of Health, Education, and Welfare, Public
     Health Service, Center for Disease Control.  National Institute for
     Occupational Safety and Health.  151-68.

Nasr, A. N. M., T. Ditchek, and P. A. Schohens.  1971.   The prevalence of
     radiographic abnormalities in the chests of fiber glass workers.   J.
     Qccup. Med. 13:371-376.
                                     415

-------
 Ness, G. 0.  1977.  Mortality patterns and occupational exposures among
      mineral wool production workers.  Presented to the Conference on
      Occupational Exposures to Fibrous and Particulate Dust and Their Ex-
      tension into the Environment.  Washington, D.C.

 NIOSH Criteria for a Recommended Standard.  1977.  Occupational Exposure to
      Fibrous Glass, DREW (NIOSH) Publication No. 77-152.

 Newhouse, M. L.  1973.  Cancer among workers in the asbestos textile industry.
      Biological Effects of Asbestos,  Proceedings of the Working Conference
      held at the International Agency for Research on Cancer, Lyon, France,
      2-6 October 1972.  Edited by P. Bogovski et al.  World Health Organi-
      zation, International Agency for Research on Cancer, IARC Scientific
      Publications No. 8, Lyon, 203-208.

 Newhouse, M. L., and G. Berry.  1973.  Asbestos and laryngeal carcinoma.  The
      Lancet.  2:615.

 Pott, F., F. Huth, and K. H. Friedrichs.  1976.  Results of animal carcinogene-
      sis studies after application of fibrous glass and their implications
      regarding human exposure, in Occupational Exposure to Fibrous Glass.
      Proceedings of a Symposium.  HEW Publication No. (NIOSH) 76-151.   U.S.
      Department of Health, Education, and Welfare, Public Health Services,
      Center for Disease Control, National Institute for Occupational Safety
      and Health.

 Pundsack, F. L.  1976.  Fibrous glass—manufacture, use and physical proper-
      ties, in Occupational Exposure to Fibrous Glass.  Proceedings of a
      Symposium.  HEW Publication No. (NIOSH) 76-151.  U.S. Department of
      Health, Education, and Welfare, Public Health Service, Center for Disease
      Control, National Institute for Occupational Safety and Health.

 Reitze,  W., et al.   1972.  Application of sprayed inorganic fiber containing
      asbestos:   Occupational health hazards.  American Industrial Hygiene
      Association Journal.  33:   3, 178-191.

 Robinson,  C., et al.   1980.   Epidemiologic and environmental study of the
      mortality patterns of rock and slag wool production workers.   This
      Conference.

 Schneider,  T.   1979.   Exposures to man-made mineral fibers in user industries
      in  Scandinavia.   Annals Occ.  Hygiene.   22:  2, 153-162.

 Selikoff,  I.  J.,  et  al.   1973.   Cancer risk of insulation workers  in the
      United States.   Biological Effects of Asbestos.   Proceedings  of the
     Working  Conference Held at the International Agency for Research on
      Cancer,  Lyon, France, 2-6  October 1972.   Edited by P.  Bogovski et al.
     World  Health Organization,  International Agency for Research  on Cancer,
      IARC  Scientific  Publications  No.  8.   Lyon.   209-216.

Sheinbaum, M.   1962.   Some health  hazards associated with the building trades.
     Am. Ind. Hyg. Assoc.  23:353.

                                      416

-------
Smith, H. V.  1976.  History, processes, and operations in the manufacturing
     and uses of fibrous glass—one company's experience, in Occupational
     Exposure to Fibrous Glass.  HEW Publication No. (NIOSH) 76-101.  U.S.
     Department of Health, Education, and Welfare, Public Health Service,
     Center for Disease Control, National Institute for Occupational Safety
     and Health.  19-26.

SRI International.  1976.  Chemical Information Services Library, SRI, Menlo
     Park, California.

Stanton, M. F., and C. Wrench.  1972.  Mechanisms of mesothelioma induction
     with asbestos and fibrous glass.  J. of the National Cancer Institute,
     43(3):797-821.

Stanton, M. F., et al.  1977.  Carcinogenicity of fibrous glass:  Pleural
     response in the rat in relation to fiber dimension.  Journal of the
     National Cancer Institute, 58(3):587-603.

Stell, P. M., and T. McGill,  1973.  Asbestos and laryngeal carcinoma.  The
     Lancet.  2:416-417.

Thoenen, J. R.  1939.  Mineral wool.  Circular 6984R.  U.S. Department of the
     Interior, Washington, D.C.

Utidjian, H. M. D., and R. T. P. deTreville.  1970.  Fibrous glass manu-
     facturing and health:  Report of an epidemiclogical study.  Presented
     at the 35th Annual Meeting of the Industrial Health Foundation,
     Pittsburgh, Pennsylvania.

Wright, G. W.  1968.  Airborne fibrous glass particles:  Chest roentgenograms
     of persons with prolonged exposure.  Arch. Environ. Health, 16:175-181.
                                      417

-------
                         DISCUSSION ON MINERAL WOOL

OUESTION   (Mr. Dickinson):  Arsenic occurs naturally with lead and copper.
           Did you say  that  30 percent of  the rock wool made in the country
           is made using  copper  slag?

ANSWER     (Mr. Fowler):  I  said that approximately 70 percent is made using
           steel mill slag and that the remainder is made using lead smelter
           slagi copper smelter  slag, iron smelter slag and natural rock.

QUESTION   (Mr. Dickinson):  Okay, but in  essence some of it is made using
           either lead  or copper melting slag?

ANSWER     (Mr. Fowler):  That is correct.

QUESTION   (Mr. Dickinson):  Since arsenic occurs naturally in nature with those
          materials did  you do  any sampling in the areas where that kind
           of slag was  being used to see what kind of exposure was being
           given perhaps  to  the  workers in the way of arsenic as opposed to
           particulates?  If we  are looking at what the problems are in using
           substitute materials  for asbestos this might be something that we
           ought to be  considering.

ANSWER     (Mr. Fowler):  I  did  not look particularly at arsenic.  We did
           look at lead exposures.  We found one single exposure to lead that
          was above the  then current OSHA standard.  That was in a single
           individual who was using personal respiratory protection as well.
           So that his  actual exposure would have been substantially less than
           that measured.  Other than that we did not find excessive exposures
           to lead.
                                     418

-------
                    MORTALITY PATTERNS OF ROCK AND SLAG
                      MINERAL WOOL PRODUCTION WORKERS

                   EPIDEMIOLOGIC AND ENVIRONMENTAL STUDY

                                     by

                            Cynthia F. Robinson, M.S.*
                              Gregory 0. Ness, M.P.H.
                           Richard J. Waxweiler, Ph.D.
                        Industry-wide Studies Branch
      Division of Surveillance, Hazard Evaluations and Field Studies
          National Institute for Occupational Safety and Health
                        Center for Disease Control
                          Public Health Service
            U.S. Department of Health, Education and Welfare
                             Cincinnati, Ohio

                                     and

                               John M. Dement, Ph.D.
                  Division of Respiratory Disease Studies
         Appalachian  Laboratory for Occupational Safety  and Health
                      Morgantown, West Virginia 26505
                                   ABSTRACT

  An epidemiolbgic and environmental study of rock and slag mineral wool produc-
  tion workers was undertaken at a plant which has been in operation  since the
  early 1900's.  Size characteristics of fibers produced by each process at the
  plant and industrial hygiene survey data were used to evaluate current and past
  exposures.  These data suggest that the average historical airborne fiber con-
  centration probably did not exceed 2.5 fibers/cc before 1935 and 1.0 fiber/cc
  after 1935.   A retrospective cohort mortality study was designed to assess
  mortality patterns.  Detailed occupational histories were compiled  on all plant
  employees.  All jobs in the plant were assigned to one of eight potential expo-
  sure categories to assess the extent of severity of mineral wool exposure and
  the effect of other significant exposures on employee mortality. Findings
  included an increase in the number of deaths due to digestive system cancer
  and nonmalignant respiratory disease among workers who had greater  than 30 years
  exposure to mineral wool or who had survived 30 years since their first expo-
  sure to mineral wool.  These findings corroborate those of the Thermal Insula-
  tion Manufacturers' mortality study of men employed in four mineral wool plants
  (Enterline'and Marsh. 1979).
Presented by Cynthia F.  Robinson, M.S.   Paper is being prepared  for publi-
cation elsewhere.
                                       419

-------
                    DISCUSSION ON ROCK AND SLAG MINERAL WOOL

 QUESTION   (Mr. Shaines):  Did you say that nothing in the data showed a signifi-
            cantly greater death rate from the slag workers versus the county
           workers?

 ANSWER     (Ms. Robinson):  There was no statistically significant excess of
            deaths.

 QUESTION   (Mr. Shaines):  That is right.  From that you conclude that there was
            an increase in deaths?

 ANSWER     (Ms. Robinson):  There was an increase of observed deaths over what
           was expected.

 QUESTION   (Mr. Shaines):  If it is not significant then it is- not an increase.
            That is the meaning of the word.

 ANSWER     (Ms. Robinson):  There were more deaths than what was expected.

 REMARK     (Mr. Shaines):  Not significant.

 REMARK     (Mr. Wright):  It was an increase but it was not statistically signi-
           ficant.   I think that is the way to say it.

 REMARK     (Mr. Shaines):  That is right.

 REMARK    (Mr.  Wright):  That does not mean it is not an increase.

 REMARK    (Mr.  Shaines):  I will go through the words again.  The probability
           was that there was not an increase.   That is what the word significant
           means.

 REMARK    (Mr.  Wright):  It means the increase was not significant at the 0..05
           level.   That does not mean the probability was that there was no
           increase whatsoever.   All it means is the chances are less than 1
           out of  20.                                                      r

 REMARK    (Mr.  Shaines):  That  is right.   The  odds are 20 to 1 that there was
           not an increase.

 REMARK    (Mr. Wright):  No,  just the opposite.   In the 5 percent level the
           odds are  20  to 1  that there is not an increase if it is not signifi-
           cant.  That  is what the odds  are.

 REMARK    (Dr. Bernstein):   I would  assume that your Null hypothesis is that
           there is probably no  increase.   If that is the case,  there is a 20 to
           1 probability  that  your Null  hypothesis is not true;  therefore it is
           a 20 to 1 probability that  there is  an increase.

REMARK     (Ms. Robinson):  If I  can restate  it  again.   I would  say  the odds are
           that this - increase  could have been seen by chance alone,  however,

                                      420

-------
         there were more deaths occurring than was  expected  on the basis  of
         our comparison population.

REMARK   (Unidentified):  There were increases in several categories of cancer
         and in almost all of these  cases there was a latency period effect
         present at 30 years.  I think if you took the information on increases
         in about three different types of cancer,  essentially all of them
         occurring at 30 years, and  combined them by nonparametric techniques,
         you would have no problem showing significance.

REMARK   (Mr. Wright):  I am fronTthe Steelworkers Union.

         Just a quick comment about  statistical significance.  Two things would
         be useful in these types of reports:  first is the  95 percent confi-
         dence interval around the results, and second is that even though it
         is useful to say this finding was or was not significant at the 0.05
         level, it might be interesting to know at what level it was
         significant.

         I would suspect for some of these numbers we are talking about maybe
         the 0.1 or 0.2 level?  Now  no scientist in his or her right mind would
         say that means those results are statistically significant, but they
         might have meaning to a worker.  For example, if a  work place has a
         result that is significant  at the 0.1 level, the professional might
         say that is not a statistically significant result  and tests have not
         proven that this stuff causes cancer or fibrotic lung disease.  But
         a worker looking at that result, if he or she understood the statistic,
         might conclude quite correctly that the chances are nine to one that
         there is a problem.  That is what it means to say it is significant
         at the 0.1 level, nine to one that there is a problem.  It is not
         enough to publish in a scientific paper how we have proven a problem
         exists but it sure is enough to worry me.  That is  what those results
         mean to me.
QUESTION (Mr. Castleman):  I gather from what you said that a
         asbestos was used, at least in that plant, and there
         about the previous job histories of the workers.  If
         pathological material or autopsy records or possibly
         more recent from someone in this group who had died,
         the state of the tissues and learn a little bit more
         going on there.                      ,
small amount of
was a question
you could get
something even
you could see
about what was
ANSWER    (Ms. Robinson):  Yes, that is a good suggestion.  Unfortunately,  there
         are very few individuals involved in the study and the rate of obtain-
         ing that kind of information and also tissue samples, which would be
         needed., is very, very low.  It has been less than 50 percent in our
         previous attempts.  However, I think we are attempting to do that.

QUESTION  (Mr. Castlemen):  What about obtaining chest x-rays from the individ-
         uals who are in bad shape from nonmallgnant respiratory disease?
                                       421

-------
 ANSWER   (Ms.  Robinson):  I do not know about that.

 REMARK   (Dr.  Konzen):   I am from TIMA.

          I think epidemiology is a very strong tool.  We use  it  a  great deal,
          as I  pointed out in my talk.   I think it  is  extremely Important  to
          remember that we are talking about one plant with  a  population of
          about 500 people that is being studied.

          As Ms.  Robinson mentioned, the Thermal Insulation  Manufacturers  Asso-
          ciation is carrying out a study that encompasses not only mineral wool
          workers but fibrous glass workers.   The first  part of the study
          reported little evidence of disease from  a malignant or a nonmalignant
          standpoint.  This was a preliminary report and a further  report, which
          is expected the latter part of this year, will look  at  many more of
          these mineral  wool workers.

          The other thing that is important  to to keep in mind is the study that
          I mentioned this afternoon.  It was a larger study on fibrous glass
          workers.   In the study we found no  excess of either  malignant or non-
          malignant disease in any category  and the overall  disease rate was
          quite low.   This study will be made available  to the regulatory  agencies
          for review.

          I think before we get excited about one plant  we should use epidemi-
          ology where it is strongest and that is in the largest  population that
          we can  involve.

REMARK    (Ms.  Robinson):   I would like to respond  to  the previous  person  who
          asked a question because he did imply that the use of asbestos at this
          plant was  considerable.   In fact, that was not the case as we under-
          stand it.

REMARK    (Mr.  Cooper):   I am from Berkeley.

          I, having been involved in a  number  of epidemiclogic studies myself,
          appreciate Ms. Robinson's  dilemma and I think  the final conclusions
          that  she came  to were  reasonable conclusions to arrive  at from this
         material.  There  are other  things to consider  and the question of
         statistical significance and  ideologic significance and social sig-
         nificance are  interrelated  but  different questions, and it would be
         improper to say there was  a nine to  one chance of someone getting a
         digestive cancer, even  a nine  to one chance of there being a problem.
         The difficulty here is you  have a relatively small increased risk
         and a relatively small population and that combination  leads to data
         that are very difficult to  use  to establish statistical significance.

         I think it would be wrong to combine into one analysis the respiratory
         tract  cancers and the nonmalignant respiratory diseases with the
         digestive cancers to show significance.  The respiratory disease
         cancers  are quite a different problem.  The interfering effects of
                                      422

-------
         smoking are so overriding in many industrial populations that they
         cannot easily explain the difference you see in this population.
         Secondly, they tend to coincide with the duration of employment so
         you tend to get a spurious appearance of latency.   I think this would
         be incorrect.

         I think the nonsignificant and rather small increase in digestive
         tract cancer is something that I would regard with concern and some-
         thing that needs further study.  We are dealing with raw materials
         that may potentially contain carcinogens.  So, I feel the very guarded
         conclusions that came from NIOSH were warrented conclusions.

REMARK   (Ms. Robinson):  It is hoped that futher follow-up of this study as
         well as the others will produce more definitive conclusions.

REMARK   (Mr. Scheckler):  I am from TIMA.

         I had an opportunity to review some of the records at that particular
         plant.  The one thing I found missing in your presentation was the
         fact that there was an interchange of employees between the studied
         plant and an adjacent plant 40 miles away owned by the same company.
         That interchange of personnel back and forth did not show on the
         records.  Now I cannot tell you the materials manufactured at the
         other plant.  That would have to be reinvestigated.  But this exchange
         of people did take place quite often.
                                      423

-------
                  INDUSTRIAL HYGIENE AND TOXICOLOGY ASPECTS OF
                          3M NEXTEL® 312 CERAMIC  FIBERS

                                        by

                 Mr. Robert S.  Larsen and Mr. William McCormick*
                                    3M Company
                                St.  Paul, Minnesota
                                     ABSTRACT

     NEXTEL® 312 Ceramic Fibers are  continuous filaments.   Individual filaments
     are comprised of metal oxides,  are transparent,  smooth and round, and are
     microcrystalline in structure.  The nominal diameter of the continuous    ^
     filaments is 11 microns.   The primary health effect associated with NEXTEL
     312 Ceramic Fibers is skin irritation.  However, tolerance to the irritation
     develops after several days of  handling.  Irritation studies and worker
     exposure data are discussed.  Airborne fiber concentrations measured in a
     3M manufacturing facility and in  a customer facility involving several
     operations have been shown to be  extremely low (maximum of 0.0005 fibers/cc
     air).   The length of the airborne fiber is quite variable  (20-6,200 microns)
     and the diameter is generally' greater than 10 microns. Airborne fibers are
     thus classified as being essentially nonrespirable.

     Toxicity studies are currently  under way to evaluate  the  fibrogenic potential
     of NEXTEL® fiber.  Some comparisons to  asbestos and fiberglass are made.  The
     inhalation hazard associated with NEXTEL® 312 Ceramic  Fibers  is  judged to be
     minimal.
     NEXTEL  312, manufactured by 3M  is a ceramic  textile fiber.   The 11 micron
diameter continuous  filaments have a  variety of properties including low
thermal  conductivity, high temperature  resistance,  and electrical  non-
conductivity.  Products  made from this  fiber include  fabrics, tapes, sleeving,
and cordage  (Figure  0).

     The first portion of this presentation will be an introduction to the
fibers and their toxicity.  Secondly, the results  of  industrial hygiene studies
will be  discussed.
* Presented by Mr. Robert S. Larsen.


                                        425

-------
Figure "0" Products made with NEXTEL  312

              Ceramic Fibers

               a.   Fabrics
               b.   Tapes
               c.   Sleeving
               d.   Cordage
                426

-------
NEXTEL FIBER AND TOXICITY

Figure 1

     The uniform roundness of the fiber is apparent in this  scanning electron
microscope photograph showing a cross section of three fractured  filaments
at 6000 X magnification.

Figure 2

     As you can see in this figure,  the round fibers have a  uniform smoothness.

Figure 3

     In the next figure, a 100 X magnification photograph shows the uniform,
transparent quality of the filaments.
     The typical NEXTEL® 312 ceramic fiber is comprised of three inorganic
Figure 4

     The
oxides in the following percentages:

                                   :ent
                                                  (Figure 4)
Aluminum oxide
Boron oxide
Silicon dioxide
62 ^percent
14 percent
24 percent
     In processing, the fiber attains a microcrystalline structure.

Figure 5

     As you can see, the micrograin crystals of the NEXTEL  fiber shown in
the top photomicrograph are approximately 0.01 to 0.02 microns in length.
This can be compared to other ceramic materials having much larger "fine-grain"
ceramic crystals  (seen in the middle photograph) and an amorphous form of
noncrystalline ceramic structure seen in the bottom photograph.
           ®
     NEXTEL  ceramic fibers are manufactured to be an 11 micron diameter con-
tinuous filament.  3M began selling ceramic fibers commercially in 1977.  As
a result, there has been insufficient time to develop a history of any possible
chronic human health effects.  Since the fibers are of such large diameter,
the inhalation hazard associated with their manufacture and use is believed to
be quite low.  Industrial hygiene surveys conducted in both manufacturing and
user facilities have confirmed this and will be expanded upon later.

     The fiber has been assessed for its skin and eye irritation potential in
the rabbit.

Table 1

     This table shows the results of the primary skin irritation study
conducted on the  fiber.  The study conducted was a conventional Draize  primary
skin irritation study1 using the Federal Hazardous Substances Act  protocol

                                      427

-------
Figure 1  Roundness of the fiber (6000 X)
                     428

-------
Figure 2  Smoothness of the fiber  surface
                 429

-------
Figure 3  Transparent Quality of the Filaments
                        431

-------
Figure 5  Contrast between three ceramic structures

          "Micrograin" - NEXTELR 312
          "Fine Grain" - Aluminum Oxide
          "Amorphous"  - Fibrous Glass
                      433

-------
TABLE 1.  NEXTEL  312 CERAMIC FIBER PRIMARY SKIN IRRITATION

Erythema and
Eschar Formation
Intact Skin
Intact Skin
Abraded Skin
Abraded Skin

Edema Formation
Intact Skin
Intact Skin
Abraded Skin
Abraded Skin


Primary Irritation
Reading
(hours)
24
72
24
72

24
72
24
72


Score: 1
Rabbit number
1
1
1
1
1

0
0
0
0


.67 - 4
2 3
1 0
0 0
1 0
0 0
Subtotal
0 0
0 0
0 0
0 0
Subtotal
Total
= 0.42
4
0
0
1
0

0
0
0
0



5
1
0
1
1

0
0
0
0



6
0
0
0
0

0
0
0
0



Average
0.50
0.17
0.67
0.33
1.67
0.00
O.OU
0.00
0.00
0.00
1.67

                           434

-------
and scoring method.2  A 0.5 gram sample of the test material was placed
on intact and abraded skin test sites on 6 albino rabbits  for a period of 24
hours.  After removal of the occluded patch,  the sites were scored for
erythema and edema formation.   At 3 of 6 intact sites and  4 of 6 abraded
sites, slight reddening was observed at the 24 hour reading.  At intact sites
the score was 0.5.  At the abraded sites the score was 0.67.  By the 72 hour
reading the irritation was reduced to 0.17 at the intact sites and 0.33 at
the abraded sites.  The total primary skin irritation score was 0.42.   This
classifies the fiber as minimally irritating dermally.

     These data are confirmed in plant experience.  People initially working
with ceramic fibers tend to experience a low grade irritation response.  The
response fades within several days of working with the fiber.  The experience
is similar to the fiberglass skin reactions noted by several researchers
(Sulzberger, et al, and Erwin).3*1*  The eye irritation results showed that
the ceramic fiber failed to elicit any signs of irritation in any animal on
study.  Again, plant experience indicates eye irritation problems in persons
handling ceramic fibers are quite rare.

     The acute skin and eye data on NEXTEL  fibers indicate a relatively
low hazard in the handling and processing of the product.   However, of primary
concern is the possible chronic effects of inhalation exposure to the fiber.
As I mentioned earlier, NEXTEL  ceramic fibers are, in the realm of fiber
dimensions, quite large.  Their diameters are in the 11 micron range and the
lengths are essentially continuous.  Short fibers are created as the result
of breakage of the continuous filament.  Breakage is of low enough incidence
in manufacture and usage to preclude a significant build up of airborne fibers.
Many of the fibers that are created are large enough to settle out of the air
rather than remain suspended.  Therefore, they are unavailable for inhalation.
Additionally, longitudinal fracturing, a process which commonly occurs with
asbestos fibers, has not been encountered with NEXTEL  ceramic fibers.

     Because of the above considerations, 3M has not conducted any fiber
inhalation studies, acute or chronic.  Fibers of large diameter and length
are considered nonrespirable.  If inhaled they would be expected to be inter-
cepted in the nasopharyngeal region of the respiratory tract and eliminated
through normal clearance mechanisms (Timbrell, Harris and Fraser).5'6  Research
conducted by Stanton, Timbrell, Wagner,7»s»8 and others indicate there is a
relationship between fiber geometry and an adverse biological response.  It
is believed that for a given fiber diameter the  longer the  fiber the  greater
the likelihood of adverse biological response.  However, the fiber diameter
must be less than 5 microns.

     Although current information suggests exposure  to NEXTEL® fibers is
extremely low, 3M is beginning an intratracheal  insufflation study  to deter-
mine the fibrogenic potential of the fiber.

     Additionally, and more importantly,  the  industrial hygiene  surveys
conducted by 3M indicate air concentrations of ceramic fibers  to be very low,
thus diminishing the concern of inhalation exposure  hazard.
                                     435

-------
 INDUSTRIAL HYGIENE ASPECTS

 Table 2

      Industrial hygiene studies have been conducted at  a 3M production
 facility and customer facility in order to determine the concentrations
 (fibers/cc) or airborne NEXTEL  312 ceramic fibers to which employees are
 exposed in addition to the physical characteristics (length, diameter) of
 the fiber.  I will discuss sampling procedures,  analytical methods,  results
 of the studies and a comparison of the results with existing OSHA standards
 and NIOSH proposals for other fiber types.

 Table 3 - Sampling

      Personal and general area air samples were  collected on open-faced  type
 AA Millipore filters.  Sampling times were up to 60 minutes in duration  and
 dependent upon the particular operation being monitored.

 Table 4 - Analysis

      The whole filter was cbunted using an Ortholux microscope.  The ceramic
 fibers are relatively easy to identify on the filter.  However, it is possible
 that other airborne fibers may have been counted in addition to the ceramic
 fibers.

 Table 5 - Results

      An industrial hygiene survey was conducted  in a textile operation using
 the fibers.  Airborne ceramic fiber concentrations found in the customer
 facility are judged to be very low for the various processes monitored.  The
 mean airborne concentration for all processes monitored was 0.00004  fibers/cc
 of air.  The airborne fibers may be characterized as being quite long with a
 correspondingly large diameter.   The mean length was 261 microns  and  the mean
 diameter 10 microns.   The airborne fibers in th§ textile plant  may be classi-
 fied  as being nonrespirable.   The inhalation for 3M customers handling the
 fibers  is judged to be minimal.

 Table 6

      Much the same results were  found in 3M's  ceramic fiber production
 facility.   However, the length and diameter of the airborne fibers in 3M's
 production facility are quite a  bit larger than  the fibers  found  in the
 customer  facility.  This is due  primarily to the inherent nature  of the
manufacturing process  which results in the generation of larger airborne
 ceramic fibers.   The mean airborne concentration was  found  to be  0.0001  fibers/
 cc of air.  The mean airborne fiber length was 986 microns  and  mean diameter
 25.8 microns.

Table 7 -  Comparison of  Results with Standards and Proposals

     None  of  the  airborne ceramic fibers found in these studies would be
considered countable under the existing OSHA asbestos standard  and proposed

                                     436

-------
   TABLE 2.  INDUSTRIAL HYGIENE STUDIES ASSOCIATED
             WITH AIRBORNE 3M NEXTEL® 312 CERAMIC
             FIBERS

I.     Sampling

II.   Analysis

III.  Results

      A.  Customer Facility

      B.  3M Production Facility

IV.   Comparison of Results with OSHA Standards and
      1JIOSH Proposal for Other Types of Fibers
                 TABLE 3.  SAMPLING

         1.  AA Millipore Filter (open-faced)

         2.  Flowrate -2.5 LPM

             Duration - up to 60 minutes

         3.  Personal and area samples



                  TABLE 4.  ANALYSIS

      1.  Ortholux Microscope

          A.  Count whole filter

          B.  Use mechanical stage

          C.  Use micrometer eyepiece

      2.  Ceramic fibers are relatively easy to
          identify but may also be counting
          other airborne fibers on the filter.
                          437

-------
                              TABLE  5.   RESULTS - CUSTOMER FACILITY PERSONAL SAMPLES
10
00
Concentration
Operations (No. fibers/cc air)
1 . Serving 0 . 00004





2. Serving 0.00001

3. Core Winding 0.000007
4. Weaving 0.00005







Mean 0.00004
Fiber
on filter Length
6 120
192
216
264
300
300
2 108
792
1 120
8 151
180
215
229
264
300
324
360
4.25 261
sizes (y)
Diameter
13.5
8.1
8.1
8.1
10.8
10.8
10.8
10.8
8.1
10.8
10.8
10.8
10.8
8.1
8.1
9.5
10.8
10

-------
                                    TABLE 6.  RESULTS - 3M PRODUCTION FACILITY
                                                                                         Range of
                                                                                      fiber sizes (y)
Sample description
Area samples taken in
fired fiber locations
Mean
i>uuueu.L.Lci(..Luu range
(No. fibers /cc air)
0-0.0005
0.0001
fumge uo. «u .
fibers on filter
0-14
4.6
Length
20-6200
986
Diameter
9.3-37
25.8
Co
vo
                                     TABLE 7.   OSHA STANDARD AND NIOSH PROPOSAL
                                                                           Fiber  size
Dtanaara or
proposal
OSHA - Asbestos
NIOSH - Fiberglass
NEXTEL Ceramic Fibers -
3M Mean
Customer Mean
No. fibers/cc air
2 (TWA)
3 (TWA)

0.0001
0.00004
Length
>5
I10

986
261
Diameter
*
£3.5

25.8
10
                           An asbestos fiber is defined as a particulate form,of asbestos,
                           longer than 5y, with a length to diameter ratio of at least
                           3 to 1 and a maximum of 5y.

-------
NIOSH Fiberglass Recommended Standard.9  Even if the fibers were considered
countable, the airborne concentrations which were detected are well within
the concentration limits set forth in  the Asbestos Standards and Fiberglass
proposal.

     In conclusion NEXTEL  312 ceramic fibers are continuous filament large
diameter fibers that present a low inhalation hazard in manufacture and
processing.  They represent a relatively safe alternative to asbestos in
the thermal protection fabric area.

BIBLIOGRAPHY

 1.  Draize, J. H., Woodard, G. and Calvery, H. 0.  Methods for the Study of
     Irritation and Toxicity of Substances Applied Topically to the Skin and
     Mucous Membranes.  J. Pharmacol.  Exp. Ther. 82:377-390, 1944.

 2.  Chapter II, Title 16 Code of Federal Regulations §1500.41 Methods of
     Testing Primary Irritant Substances and §1500.42 Test for Eye Irritants.

 3.  Sulzberger, M. B., Baer, R. L., Lowenberg, C. and Menzel, H.:  The
     Effects of Fiberglass on Animal and Human Skin - Experimental Investi-
     gation.  Ind. Med. 11:482-84, 1942.

 4.  Erwin, J. R.:  Fiberglass Plastics.  Ind. Med.:  439-41, 1947.

 5.  Timbrell, V., The Inhalation of Fibrous Dusts.  Section V - Human
     Exposure to Asbestos:  Dust Controls and Standards.  Ann. NY Acad.
     Sci.:  132:255-73, 1965.

 6.  Harris, R. L. and Fraser, D. A., A Model for Depositon of Fibers in the
     Human Respiratory System.  AIHA Journal:  37:73-89, 1976.

 7.  Stanton,  M. F., Layard, M., Tegiris, A., Miller, E., May M. and
     Kent, E.:  Carcinogenicity of Fibrous Glass:  Pleural Response in the
     Rat in Relation to Fiber Dimension.  J. Natl. Cancer Inst.:  58 Mo. 3:
     587-603,  1977.

 8.   Wagner, J.  C.,  Berry, G., Skidmore, J.  W.:  Studies of the Carcinogenic
     Effects of Fiberglass of Different Diameters Following Intrapleural
     Inoculations in Experimental Animals.   Occupational Exposure to Fibrous
     Glass-Proceedings of a Symposium, HEW Publication No. (NIOSH) 76-151
     193-197.   Washington, DC, U.S.  Department of Health, Education, and
     Welfare,  1976.

9.   Criteria  for a  Recommended Standard, Occupational Exposure to Fibrous
     Glass.  DHEW (NIOSH)  77-152.   Washington, DC, U.S.  Department of Health,
     Education and Welfare,  1977.
                                     440

-------
                        DISCUSSION ON CERAMIC FIBERS

QUESTION    (Dr. Cooper):  If there is no question on this particular paper
            I would like to clarify my comments on the previous paper* if
            this is in order.

ANSWER      (Chairman Rowe):  That is fine.

REMARK      (Dr. Cooper):  There are some individuals here who seem to have
            the impression that I said that I felt the NIOSH study showed
            that mineral wool caused an increase of digestive cancer.  This
            was not what I intended to convey at all.  The point I meant to
            make was that I agreed with the conclusions of Ms. Robinson
            that the study was inconclusive and that this was an area that
            certainly deserved further study.
                                      441

-------
                            TOXICOLOGY OF ARAMID FIBERS

                                        by

                              C. F. Reinhardt,  M. D.
            Haskell Laboratory for Toxicology and Industrial Medicine
                     E.  I.  du Pont de Nemours and Company
                            Wilmington, Delaware 19898
                                      ABSTRACT

                                                     ®         A
    Du Font's two high performance aramid fibers,  Kevlar and Nomex , are function-
    ally qualified and cost-effective as asbestos  replacements in many industrial
    applications.  Both fibers are based on aromatic  polyamides, which confer  excel-
    lent high temperature stability and, with Kevlar  ,  outstanding strength, stiff-
    ness and frictional properties over a wide temperature range.  Several trade
    programs are under way to replace asbestos in  friction products, gasketing,
    plastic reinforcement, thermal Insulation and  protective clothing.
                A          ®
    Neither Nomex  nor Kevlar  fibers produce allergenic reactions on skin contact.
    Initial inhalation and/or intratracheal insufflation studies of fibers of  Nomex
    and polymeric dust of Kevlar® in rats showed that both materials produced  only
    minimal tissue reaction (nature of reaction varied  with particle size and  shape)
    in the lungs with no collagen formation.  These observations appear to meet the
    criteria of a biologically inert dust, namely: (a)  absence of collagen forma-
    tion; (b) potential reversibility of the lesions; and (c) maintenance of normal
    architecture of the air spaces.

    Results of these preliminary studies indicate  that  the use of aramid fibers to
    replace asbestos poses no significant health hazard to persons processing  ara-
    mids or to the user of the final product.  More extensive toxicological studies
    are planned'to confirm these results.
INTRODUCTION

     Du Font's two aramid fibers, Nomex  and Kevlar , are rapidly gaining accep-
tance as commercially viable replacements for asbestos in a number of applica-
tions such as insulation, flame barriers, thermal  protective clothing, and
particularly, friction  products.

     Key to the functional acceptability of Nomex   and Kevlar   is their  chemical
structure.  Both are based on aromatic polyamides  .and differ only in the sub-
stitution position on the aromatic  rings.  These fibers are inherently flame


                                         443

-------
 resistant and do not melt.  In fact, neither will sustain combustion in a nor-
 mal atmosphere when the ignition source is removed.  Thermal and oxidative
 stabilities are also outstanding, so that each can withstand long-term in-use
 exposure at very high temperatures for organic fibers.
           ®          ®
      Nomex and Kevlar fibers have been sold commercially for about 15 and 8
 years respectively.  To date, industry has consumed millions of pounds of each
 material with no known health hazards from the fibers either in manufacture or
 use.

      I will turn now to a description of the procedures and results of our
 toxicological testing of Nomex®and Kevlar®.

 PROCEDURES AND RESULTS

      Human contact with these fibers is most likely to be by the dermal route
 along with potential respiratory exposure, so we have concentrated our efforts
 on these exposure routes.  Both Nomex® and Kevlar  have been studied to evalu-
 ate skin irritancy and skin sensitization potential in animals and man.  These
 studies involved primarily human volunteer panels in which from 100 to 200 in-
 dividuals per study were patch tested.   They showed no potential for skin sen-
 sitization and only minimal chance for skin irritation to develop following der-
 mal contact with fabrics of either Nomex® or Kevlar® .  Because these fibers,
 especially Kevlar  , are stiff, potential exists for causing abrasive skin
 irritation under restrictive contact.

      To evaluate the potential problems that might be associated with respira-
 tory exposure to Nomex® , the long-term lung response to dust generated by
 shredding and grinding a paper of Nomex  aramid was studied.  Two and one—half
 milligrams of the material,  suspended in physiological saline solution, was
 instilled into the trachea of rats.   The test material in the lung appeared
 as acicular,  oblong, or rod-shaped particles varying in size from 2-100u in
 length and 2-30u in diameter.   Tissue response was measured by evaluating the
 respiratory tract histopathologically.   Groups of rats were examined 2 and 7
 days,  3 and 6 months,  and 1  and 2 years following treatment.

     No signs of an adverse  response to the test substance were seen - these
 included observations  for clinical signs,  growth as measured by body weight
 data,  and mortality patterns.   At each  of  the sacrifice intervals, the test
 material was  observed  microscopically in the lung tissue.   However,  the non-
 specific tissue  response was characteristic of that experienced generally with
 foreign  particles  in the lung;  that  is,  an initial transitory acute inflamma-
 tory response  followed by foreign body  granuloma formation.   The later response
 was provoked by  the larger,  non-respirable sized dust particles in the range of
 30 X lOOu.  The  smaller,  respirable  sized  particles, <10u,  produced only a
 negligible dust  cell reaction  similar to that seen with nuisance particulates.
 During the post-exposure  recovery period,  most of the dust  laden macrophages
 were eliminated  from the  lung within three months.

     These mild tissue reactions  became  less obvious as the post-exposure time
 increased and the exposed lungs returned to essentially normal architecture
without  formation.of collagenized fibrosis two years after  exposure.   This ex-

                                      444

-------
pertinent In rats  irit rat radically insufflated with fibrous dust of Nomex  did
not show any progressive pulmonary fibrosis, collagenization or clinical bron-
chopulmonary distress.

     We next concentrated our efforts on Kevlar  since it is a rather unique
fiber in that it has a greater tendency than most fibers to fracture along the
fiber axis.  In some textile processing operations it has a propensity to form
some small fibrous particles.  That characteristic, along with Du Font's inter-
est in very short, highly fibrillated pulp forms as an asbestos replacement,
has caused us to center our concern on these small particles.  We started with
dust converted from raw polymer, rather than dust converted from fiber, since
we could not isolate enough fiber dust from textile processing operations for
our tests.

     The polymer dust tested contained a low, but undetermined proportion of
fibrous particles considered to be in the respirable range, <1.5u in diameter
and between 5 and 60u in length.  Larger, non-respirable particles ranged up
to 150u in diameter.  Particle shapes were variable.  Chemically, this material
is identical to fiber particulates.  In our first study, the acute inhalation
toxicity potential was measured by generating the highest dust concentration
possible and by exposing rats to this atmosphere for 4 hours.  Concentrations
in the exposure chamber were analyzed gravimetrically and averaged 150 mg/m3.
Only minor signs of a response, such as decreased activity, were seen during
the exposure period.  No signs of a response were seen post-exposure.  The acute
lethal concentration in rats is thus in excess of 150 mg/m3.  However, as in-
dicated above, only a small percentage of the dust was of respirable size.

     Since we were concerned with not only the effects of a single massive ex-
posure but also with potential cumulative effects following a series of expo-
sures, a subacute inhalation study of the Kevlar® polymer dust followed.  In
this experiment, rats were exposed to 130 mg polymer dust per m3 air for 4 hours
per day, 5 days per week for each of 2 successive weeks.  Observations of the
rats for clinical response to the dust were made daily.  A reference group of
control rats exposed to houseline air only was run concurrently.  Immediately
following the last exposure, half of each group, test and control, was sacri-
ficed" and each rat was given a complete gross pathological examination includ-
ing weights of the lungs and other major organs.  Microscopic examinations of
21 tissues/organs were conducted.  The remaining rats were sacrificed and
examined similarly following a 14-day recovery period.

     During the exposures, test rats were slightly less active and gained some-
what less weight than did the controls.  This was not seen during the recovery
period.  Gross pathological examination and organ weight data revealed no treat-
ment-related differences.

     Microscopically, rats examined after the 10th exposure  showed numerous
macrophages throughout the lung tissue.  At the end of the recovery  period,
these macrophages decreased in number and tended to form discrete clusters  in-
dicating a typical non-specific response to foreign particles  in the lung.   All
other tissues and organs examined either immediately following exposure or  after
the recovery period were free of treatment-related changes.


                                      445

-------
      Repeated exposure of rats to 130 mg of polymer dust/m3 produced only mild
 clinical symptoms during, but not after, exposure.  A slight change was produced
 in the lung, manifested by phagocytosis of the test material.  This typical dust-
 call reaction was also observed following the 14-day recovery period.

      To evaluate the tissue response on a long-term basis, the next study in-
 volved intratracheal instillation of 25 mg of Kevlar® polymer dust in physio-
 logical saline solution into rats.  A group of control rats treated with saline
 alone was included.  Rats were then held without further treatment and were sac-
 rificed at 2, 7, and 49 days and 3, 6, 12 and 21 months after treatment.

      At each sacrifice, a complete gross pathologic examination including weights
 of the major organs was conducted.  Histopathologic examination of the respira-
 tory tract was also conducted.

      Over the 21-month test period, mortality rates, clinical observations, and
 gross autopsy results were similar for test and control groups.

      Following instillation, particles could be detected in lung tissue, the
 large particles, approximately 100-150u in diameter, mainly in terminal bron-
 chioles, smaller-sized particles, approximately 5u in size, in alveolar ducts.
 The initial, non-specific inflammatory response subsided within 1 week and
 foreign body granulomas containing the larger non-respirable dust particles were
 seen in later sacrifices.  Negligible amounts of collagen were present around
 the dust-laden large granulomas.   All tissue responses to the dust particles
 decreased with increasing time post-treatment.

      From this experiment, we conclude that the intratracheal instillation of
 respirable and non-respirable-sized polymer dust particles of Kevlar® produced
 only a non-specific dust cell reaction similar to that seen with inert dusts.
 The material is considered non-fibrogenic and only mildly irritating since the
 pulmonary lesions showed marked reversibility, no collagen formation associated
 with the respirable-sized dust particles, and only the large, non-respirable
 dust particles were able to produce foreign body granulomas.

      We are currently engaged in a program to evaluate fibrous particles de-
 rived from ground Kevlar® aramid fiber (pulp), for which we expect to find wide
 use as an asbestos replacement.   This includes a subacute inhalation study with
 extended recovery times and insufflation with the dust of fibrous particles.
 The need for other work,  including the possibility of a lifetime inhalation
 study,  will be evaluated as the results of the currently planned studies become
 available.

 COMMENTARY

      These toxicological  test results give us confidence that neither Nomex®
nor Kevlar*  poses  a significant health hazard to our workers, to those who
process  the  fiber  into  asbestos replacement products, or to the end users of
those products.  This position is  supported by the safe use of millions of
pounds of aramid fibers in a  range of other end uses over many years and good
medical surveillance of our employees who have handled them.   While the test
conditions utilized do  not simulate  directly real-life exposures to these pro-


                                      446

-------
ducts, we believe that, if anything, the tests exaggerate use conditions.  Our
toxicological testing program is continuing in order to document our hazard
assessment and to provide added support as the range of end uses increases.
                                      447

-------
                          DISCUSSION ON ARAMID FIBERS

 QUESTION (Mr. Spitzer):  I am from the Consumer Product Safety Commission.

          Three quick technical questions:   (1)  how many animals were in each
          group that you used; (2) what about the spontaneous tumors  in each
          group; and (3) have you done any transmission electron microscopy, and
          specifically looked at the type 1 to type 2 cell ratio in the lung
          tissue?

 ANSWER   (Dr. Reinhardt):   In response to  the first question,  there  were approxi-
          mately 40 animals in each group and 5  were sacrificed at  each of the
          intervals, holding the remaining ones  until the end.   Your  last ques-
          tion about the electron microscopy, that has not been done.  And your
          second question about tumor incidence  will be answered by our path-
          ologist who reads these slides, Dr. Lee.

 ANSWER   (Dr. Lee):  Each period we sacrificed  five rats.  At  the  end  of 21
          months there were about five rats left.  Therefore, it is almost
          impossible to check the carcinogenicity with that small a number of
          animals.  So we cannot answer that question.

 QUESTION (Dr. Lewinsohn):   I am from Raybestos-Manhattan.

          With regard to the question of carcinogenicity,  I assume  that you
          will be conducting survival type  experiments to determine whether
          there is an incidence of carcinogenicity in these animals.  And I
          wonder have you considered the instillation of fiber  into the pleural
          cavity directly,  in other words,  the Stanton type experiment?

 ANSWER   (Dr. Reinhardt):   As far as answering  your first question,  yes, def-
          initely.   In particularly the longer term type studies that we do,
          the  animals will  be held for their lifetime to evaluate any carcin-
          ogenic potential.   In elaborating a bit on Dr. Lee's  response,  even
          though the numbers of animals was relatively small  at the end of the
          study so that it  would make it difficult  to evaluate  with great
          assurance the absence of any carcinogenic potential,  there  was no
          evidence that this was a problem  based on the studies that  we have
          done up to this point.   Right at  the moment we do not have  any plans
          to carry  out  pleural instillation.   We feel that  the  insufflation* studies
          and  the more  physiological inhalation  studies would be appropriate.

REMARK    (Dr.  Cooper):   I  am from Berkeley.

          Several years ago,  Pimental,  Avila,  and Villar,  in  Portugal,  des-
          cribed  pulmonary  reactions in a variety of industries where more or
          less  insoluble  and  durable dust was  inhaled.   I  looked into this
         briefly and it  appeared that  there was a  pattern of exaggerated gran-
         ulomatous  response  in a number of individuals, including  individuals
         who had worked with a number  of the synthetic textile fibers.   I have
         not heard anything  about this lately,  but it is  suggested with the
         type of response that you see in  your  animals that  an occasional

                                       448

-------
         Individual might have an exaggerated granulomatous response to
         the deposition, inhalation or retention of some of these dusts*
         which simulates a sarcoid-like reaction.  I just wondered if there
         have been any human experiences in the United States that would
         suggest that occasionally individuals would have this.  It is not
         a fibrosis, it is not a pneumoconiosis, but it could create an
         Impression that you are getting a pneumoconiosis when it really
         is probably a highly individualized response.  I wonder if you
         would comment on this general topic.

ANSWER   (Dr. Reinhardt) :  I am also familiar with the Portugal study.  To
         the best of my knowledge I do not know of any actual studies
         where there are autopsy findings correlating a response such as
         you describe, this granulomatous response, with the exposure to
         specific fibers.  In the Portugal study, I think there were numerous
         fibers in the lungs of these people, but their previous occupations
         were not well documented.  I appreciate your comment.  I think that
         It is something that perhaps needs to be pursued.

QUESTION (Chairman Rowe):  Did you examine any other tissues to see if there
         were particles in those tissues?  And this is a general question:
         What is the relationship between a granulomatous response and, say,
         the development of fibrosis, if any?

ANSWER   (Dr. Reinhardt):  We did not examine the other tissues specifically
         to see if there were fibers that had been translocated.  I would
         like to refer that second question back to Dr. Lee, our pathologist.

ANSWER   (Dr. Lee):  We checked lymph nodes and after 1 week the small
         particulates were transferred to lymph nodes without any
         significant inflammatory reaction.  Your second question regarding
         pulmonary fibrosis; it was not striking to observe the more
         fibrogenic reaction in the large granuloma.  So we think these
         are nonfibrogenic fibers.
                                    449

-------
         ENVIRONMENTAL  EXPOSURE CONSIDERATIONS DUE TO THE RELEASE
                 OF GRAPHITE FIBERS DURING AIRCRAFT FIRES

                                     by

                            Dr.  Benjamin Sussholz
                    TRW Defense and Space Systems Group
                     Redondo Beach, California  90278
                                  ABSTRACT

    Estimates are developed of the  environmental criteria associated with micron
    size carbon fibers released from burning graphite composites during aircraft
    fires.  Empirical fiber distributions were determined from test results of
    exposure of graphite composite  structural elements to large pool fires.  Fre-
    quency and dimensions of the micron carbon fibers were characterized.  Fibril-
    lated particles were observed which constituted the predominant source of
    the micron fiber data.  The fibrillation phenomena were attributed to fiber
    oxidation effects caused by the fire environment.  Estimates were established
    of micron carbon fiber concentration and exposure levels for an extreme case
    of an aircraft accident, and comparisons were made with OSHA criteria for
    asbestos exposure.
     Estimates have been developed of the dimensions  and frequency of occur-
rence of small-diameter carbon fibers released  from burning graphite compos-
ites during  aircraft fires as a frame of reference  for comparison with envir-
onmental exposure criteria established for known fiber hazards.

     Development  of the micron fiber criteria was based principally on data
reduction and analysis of sticky paper records  obtained during large pool
fire tests of spoiler and cockpit structural samples  conducted at the Naval
Weapons Center, China Lake, in May 1978.1  The  sticky paper instrumentation
consisted of sheets of adhesive coated paper of approximately 20 cm x 25 cm
in dimensions located on wooden platforms of about  0.6 m height above ground.
Station locations ranged about 75 m to 115 m from the test samples covering
an arc of about 100 degrees.  Data reduction consisted of determining carbon
fiber dimensions  by means of optical microscopy.

     An effort was made to determine appropriate diameter and length bounds
for carbon fibers that may be potentially respirable by humans and of interest
toward establishing fiber hazard criteria.  There appears to be evidence  that
durable fibers of similar dimensional characteristics constitute health
hazards simply because of physical properties  rather than chemical nature.

                                       451

-------
 Extensive studies have been performed regarding health hazards  associated
 with asbestos and glass fibers with very limited research relative  to  carbon
 fibers.

      Due to the lack of specifically developed guidelines regarding carbon
 fiber hazards it has been generally recommended that the existing framework of
 information on asbestos and glass fibers may be applied toward  establishing
 bounds on carbon fiber criteria.  Based on a review of the state of the art3"7
 the limiting carbon fibers dimensions of interest toward health hazards were
 assumed as follows:  (1) diameter less than 3 microns, (2)  length less than
 80 microns, and (3) length-to-diameter ratio of 3 or greater.

      During the course of data reduction of the NWC sticky paper records par-
 ticles were observed which manifested a splitting or fibrillation process in
 that single fibers appeared to be segmented longitudinally along the axis of
 the fiber into individual fiber elements or essentially fibrils.  Examples of
 particles of this nature are shown in Figure 1.  In some cases  the  particles
 are characterized by substantial fragmentation of the slender fibers into
 short segments.  Representative fibrillated fibers with high micron particle
 density are shown in Figure 2, with an enlarged view of a high  density region
 presented in Figure 3.

      Evaluation of the NWC data indicated that the fibrillated  particles con-
 stituted the predominant source of micron size fibers of interest toward con-
 sideration of potential health hazards.  An effort was made to  separate some
 of the fibrillated particles from the adhesive on the records for detailed
 examination by means of a scanning electron microscope.  However, a difficulty
 developed in preparation of the fiber sample for SEM photography in that com-
 plete removal of the adhesive was not possible without a thin layer adhering
 to the fiber surface.  This layer was significantly greater than the depth of
 focus of the SEM equipment, and therefore,  the particle could not be observed.

      Recommendation was made to NASA that Fetri dish instrumentation be incor-
 porated  in forthcoming pool fire tests of graphite composite structures at the
 Dugway Proving Ground in order that free carbon fibers may be collected unen-
 cumbered by the adhesive coating associated with sticky paper records.  The
 DPG  tests were conducted during October-November 1979.  Petri dish  instrumen-
 tation was distributed over an arc of about 120 degrees at a distance  of
 approximately 110  m from the test samples.   A comparison of the NWC and DPG
 test  characteristics is presented in Table  1.

     Analytical results for the length versus  diameter distribution for NWC 11
 is shown  in Table  2,  with  a similar tabulation for NWC 13 given in  Table 3.
 For the  case  of NWC 11  a total of 191 micron fibers (D<3y,  L<80y) were observed
with a corresponding frequency of occurrence of 38.4 percent.   The  number of
 single fibers with  lengths  >  1 mm was 32, or 6.4 percent.   The  ratio of micron
 fibers to  single fibers  with L >  1 mm was therefore 6.0.  Relative  to  the NWC
 13 data,  262 micron fibers  were~measured with  a frequency of 49.5 percent.
The number of single  fibers with  L >  1 mm was  30,  or 5.7 percent.   The ratio
of micron fibers to single  fibers with L >  1 mm was 8.7.
                                     452

-------
GAGE LOCATION SON, SOW
GAGE LOCATION SON, OE/W
  Figure 1.  Examples of Fibrillation Effect During NWC Spoiler Test 11

-------
            NWC 11  140N, 60W
            NWC 13- 180N, 40W
700 H
1400
    Figure 2.   Representative  Fibrillated Fibers with High Micron  Particle Density

-------
                                              NWC 13- 180N, 40W
100 M
                      Figure 3.  Enlarged View of  High Micron Particle Density Region

-------
                                          TABLE  1.   TEST  DATA SOURCES
00
Test Test Test
location designation sample
Naval WC "
Weapons
C6nter NWC 13
D-l
Dugway
Proving D-2
Ground
D-3
737 Spoilers
F-16 Cockpit

Various
structural
elements

Burn
Composite Composite Test duration
type mass (kg) configuration (min)
T300/5209 3.8 JP-5 pool fire 4
T300/5208 22.5 (12 m x 18 m) 6
T300/5208 46.2 JP-4 pool fire 20
T300/5208 45.5 (10.7 m diameter) 20
T300/5208 70.8 20
Test
instrumentation
Sticky paper
Sticky paper
Petri dish
Petri dish
Petri dish

-------
TABLE 2.  SPOILER TEST NWC 1 I—LENGTH VS DIAMETER CORRELATION
Diameter
interval
(microns)
0-1
1-2
2-3
3-4
4-5
5-6
Ul
vo
6-7
7-8
>8
Total
Percent
Length interval
5- 10-
10 20
12 17
6 18
21
2 5
2 5
1
2
1
1
22 71
4.4 14.3
20-
40
8
33
22
5
3
1
3
1
15
91
18.3
40-
75
2
17
28
4
-
2
6
4
23
86
17.3
75-
150
4
8
23
11
9
6
6
3
5
75
15.1
150-
300
-
3
14
10
7
5
4
-
1
43
8.7
300-
600
-
1
7
10
6
5
9
4
4
46
9.3
(microns)
600-
1000
-
1
3
2
5
2
5
2
7
27
5.4
1000-
2000
-
-
2
5
3
4
4
2
2
22
4.4
2000- 4000-
4000 8000
-
-
1 1
2 1
4 1
•M 1—
1
1 1
9 4
1.8 0.8
8000-
16,000 Total
43
87
1 122
57
45
26
39
18
60
1 497
0.2 100

Percent
8.7
17.5
24.5
11.5
9.1
5.2
7.8
3.6
12.1
100.0


-------
TABLE 3.  COCKPIT TEST NWC  13—LENGTH VS DIAMETER CORRELATION
Diameter
interval
(microns)
0-1
1-2
2-3
3-4
4-5
5-6
6-7
7-8
>8
Total
Percent
Length interval
5- 10-
10 20
14 16
11 30
7
1
-
-
_ _
- _
- _
25 54
4.7 10.2
20-
40
18
57
31
5
1
-
-
-
-
112
21.2
40-
75
6
36
27
9
3
-
-
2
1
84
15.9
75-
150
1
30
32
5
4
7
5
4
5
93
17.6
150-
300
-
11
14
14
7
2
3
4
8
63
11.9
300-
600
-
2
7
7
6
2
2
3
5
34
6.4
(microns)
600-
1000
-
2
4
5
1
1
2
1
6
22
4.1
1000-
2000
-
-
10
7
3
1
1
-
8
30
5.7
2000- 4000- 8000-
4000 8000 16,000 Total
1 - - 56
179
3 - - 135
2 1 56
1 26
13
13
14
4 - - 37
8 2 2 529
1.5 0.4 0.4 100
Percent
10.6
33.8
25.5
10.6
4.9
2.5
2.5
2'.6
7.0
100.0*


-------
     The ratio of fibrillated fibers to nonfibrillated fibers  was  22 percent
in the case of NWC 11 as compared to 30 percent for NWC 13.  An average number
of about 10 individual particles per fibrillated fiber were  observed for both
sets of data.-  In general, the distributions for the two tests were quite
similar.  Therefore, it appeared reasonable to assume a combination of the
associated micron fiber data for the purpose of the present  criteria analysis.
A comparative plot of the integrated micron fiber characteristics  encompassing
a total of 1026 fibers is shown in Figure 4.  Although not indicated, the
lower limits for the plots of Figure 4 were respectively 0.4 microns for
diameter, 2 microns for length and 3 for length to diameter  ratio.

     With reference to Tables 2 and 3, the average frequency of occurrence for
NWC 11 and NWC 13 of single fibers in the micron fiber domain  is 44 percent as
compared to 6 percent for lengths greater than or equal to 1 mm, or a ratio of
7.3.  To account for incomplete data reduction of the fibrillated  fibers, it
appears reasonable to increase this ratio to 10.

     It is noted that a predominant portion of the observed  particles in the
micron domain of diameters less than 3 microns and lengths less than 80
microns were associated with fibrillated fibers.  In the data  reduction of the
NWC sticky paper records location of isolated particles of such dimensions was
extremely difficult since the frequency of occurrence was quite small.  It is
quite probable that particles of this size with very low settling  velocities
would have been dispersed to significant distances downrange before being
deposited on the ground.

     A study by means of SEM photography of free carbon fibers collected
during the DFG tests yielded an insight into the causes of fibrillation
effects.  Examples of the different manifestations of the fibrillation phe-
nomena are shown in Figures 5 and 6 with arbitrary categorization  of the types
of effects.  These photographs offer striking evidence of the  spectrum of
oxidation effects caused by the fire environment leading to  what has been
designated as fibrillation phenomena and indicating conclusively a source of
micron size fibers from a parent single carbon fiber.

     It was of interest to study the pattern of separation of  single fibrils
of significant lengths.  The result in one case is reflected by the sequence
of photographs presented in Figure 7, each corresponding to  3000X magnifica-
tion with the indicated vertical scale of 2 microns and horizontal scale of
50 microns applicable similarly to each photograph.  The overall length
covered was about 250 microns.  Each photograph is essentially an extension
at the left of the photograph immediately adjacent and directly below it with
a small overlap for continuity and identification.

     Separation of the two fibrils in the uppermost photograph appear to con-
tinue over a length of about 100 microns until the advent of a third fibril
in the middle photograph.  Subsequently the three fibrils merge within a
length of about 125 microns with evidence only of a single fine line of  sepa-
ration at the termination in the bottom photograph.  At  the far right of  the
bottom photograph, a fiber is noted with an average diameter of about  1 micron
and length of about 20 microns.  However, over a length  of about 3 microns  at
each end the fiber diameter is gradually reduced down  to a value of  a  small

                                      461

-------
 DIAMETER SPECTRUM
LENGTH SPECTRUM
30
25
P
Z
Sw

£
RELATIVE OCCURf
0 5


6

0
* 	

















































	 1

































30
25

5 20
£
8
|«
u)
>
P.o
E

5
0










•

0











0











(0 3











10 '












       DIAMETER .MICBONSI
                                                            LENGTH IMICKONSI
LENGTH TO
 DIAMETER   |
  RATIO     5
                                30     40     SO
                                LENGTH TO DIAMETER RATIO
                Figure 4.  Micron Fiber Characteristics

-------
SINGULAR
  AREA
                                 HOLLOW TRUNK
FLAKING
              30 M
                      Figure 5.  Representative Fibrillation Effects  -  I

-------
EYE-OF-THE-NEEDLE
                                                 SUBMICRON FIBER
                                                (D = 0.4n,  L = 8.7 p)
      Figure 6.   Representative Fibrillation Effects  -  II

-------
Figure 7.  Fibrillation Phenomena Over Extended Length

-------
fraction of a micron.  This manifestation of diameter reductionjat the ends
is quite characteristic of the micron size fibers associated witih the fibril-
lated particles evaluated in the present study.                . i

     The foregoing results indicate that considerable degradation of the fiber
structure may be attributed to the high temperature fire environment.  There
appeared to be singular areas where preferential oxidation occurred with
frequent irregular patterns in the fibril evolution.  Studies of carbon fiber
microstructure8"12 indicate the existence of various types of precursor
defects (inorganic particulate, irregular voids) and graphite fiber flaws
(cavities, pockets of low crystalline density) which can affect oxidation
resistance.  In addition, sodium impurities can cause catalytic oxidation in
carbon.

     Micron fiber criteria were developed on the basis of the following meth-
odology:  (1) assume NASA criteria1^ for single fibers with lengths greater
than or equal to 1 mm (NL ^ 1 mm)» (2) determine the frequency ratio (FR) of
micron fibers to single fibers with L > 1 mm, (3) estimate an enhancement
factor (EF) to account for data base limitations, and (4) multiply the re-
spective factors to yield the micron fiber number as follows:

                      NMF = (NL > 1 mm) X (FR) X (EF)

As noted earlier, the frequency ratio of micron fibers to single fibers of
lengths greater than or equal to 1 mm is estimated to be a factor of 10.
However, there are various limitations and uncertainties regarding the data
base available for the purpose of establishing this ratio.

     A number of these limitations are briefly outlined as follows:

     •    Considerable difficulty was encountered in the data reduction
          of isolated micron fibers due to the sparcity of occurrence to
          the extent that data of this nature was essentially discounted.

     •    Analytical results encompass only data from close-in ranges
          with no basis for judgement regarding downrange characteristics.

     •    Fibrillated fibers constituted the principal source of micron
          fiber data with the relative frequence of occurrence of high
          density micron fiber regions as,somewhat indefinite.

     •   Micron fiber criteria have been evaluated only on the basis of
         NWC test data.

     •   Prediction of the extent of fibrillation effects associated
         with aircraft accident scenarios is highly uncertain.

     •   Potential impact of significant diameter reductions at the micron
         fiber  ends  may warrant consideration.
                                    468

-------
     •    Data collection technique involving pressure  of protective
          acetate cover sheet over sticky paper adhesive surface may have
          contributed toward separation of micron fibers from parent
          fibrillated particles.

     •    Appropriate scaling factors for increased composite mass and
          complex structural configurations are unavailable.

     •    Micron fiber source enhancement due to wind conditions,
          explosions, turbulence and mechanical disturbances  has not
          been evaluated.

     On the basis of the foregoing limitations, it appears reasonable to
introduce an enhancement factor of 10 in the frequency  ratio  of micron fibers
to single fibers with lengths greater than or equal to  1 mm.

     Micron fiber criteria estimates based on the analyses of the present
study are presented in Figure 8.   The total number of micron  fibers per kilo-
gram mass of carbon fiber released is specified as 5 x  1011,  with a corre-
sponding micron fiber mass fraction of carbon fiber released  as 5 percent.
The spectral distribution of micron fiber dimensions reflects a relatively
uniform pattern over the respective diameter and length intervals.

     The criteria values of Figure 8 constitute a description of the micron
fibers generated at the source during an aircraft accident involving a fire
only.  It appeared of interest to evaluate an extreme case estimate of the
potential exposure to the micron fiber plume propagating downwind.  Results
of the upper limit estimates are shown in Figure 9.

     The mass of carbon fiber exposed to the fire was assumed as 1000 kg re-
sulting in a total number of 5 x 1012 micron fibers released.  A schematic of
the carbon fiber plume profile is shown in Figure 9. For the purpose of the
present analysis no consideration is given to the particulate rainout occurr-
ing in the close-in regions, with attention focussed principally on exposures
beyond the plume cross-section designated in Figure 9 as downrange source
area.  No loss of micron fibers is considered for the close-in areas with the
total source of 5 x 1012 micron fibers assumed available for propagation down-
range.  In addition, reduction of concentration levels  due to dispersion of
the fiber cloud is neglected.

     The peak carbon fiber concentration and exposure levels were estimated as:


                        (CCF>max = 5.3 x 10* f/m3


                                   3'2 x 1C)8

Corresponding values for the OSHA asbestos standard3 are:

              C   - 2 x 106 f/m3 (8-hr time weighted average)
                                     469

-------
     •  MICRON FIBER FREQUENCY RATIO RELATIVE TO SINGLE FIBER LENGTHS > 1MM	10



     •  ENHANCEMENT FACTOR TO ACCOUNT FOR LIMITATIONS AND UNCERTAINTIES   	10



     •  MICRON FIBERS PER KILOGRAM MASS OF CARBON FIBER RELEASED


        -  ASSUME NASA VALUE FOR LENGTHS > 1MM  = 5 X 109 FIBERS

        -  MULTIPLY BY MICRON FIBER FREQUENCY RATIO AND ENHANCEMENT FACTOR


              NUMBER OF MICRON FIBERS  = 15 X 109] X  flOj X flOJ  =  5.X1011



     •  MICRON FIBER DIMENSIONS
•xj
o
LENGTH
(MICRONS)
2-10
10-20
20-30
30-40
40-60
60-80
PERCENT
OF TOTAL
10
24
21
16
16
13
DIAMETER
(MICRONS)
0.4-1.0
1.0-1.5
1.5-2.0
2.0 - 2.5
2.5 - 3.0
—
PERCENT
OF TOTAL
21
27
20
23
9
—
         MICRON FIBER MASS PER KILOGRAM OF CARBON FIBER RELEASED



         -   AVERAGE MASS PER FIBER:   M = J D2  L p = f \1.5 X 10~4)  \3Q X 10"4) ^j.8J = 1 X TO'10 GM



         -   TOTAL MICRON FIBER MASS:  My = fs X 1011J M X 10~10j  =50GM


         -   MASS FRACTION OF CF RELEASED:  5 PERCENT


                           Figure 8.  Micron Fiber Criteria Estimates

-------
MASS OF CF EXPOSED TO FIRE

MASS OF CF RELEASED (1%)

NUMBER OF MICRON FIBERS RELEASED

TOTAL MICRON FIBERS RELEASED

                       Nf
CONCENTRATION C -  	
              Nf „ FIBER NUMBER

             - Of = SOURCE AREA

              Vw = WIND VELOCITY

              tb = BURN TIME

 PARAMETER ASSUMPTIONS

     D =200M  V =0.5M/SEC    tb=60SEC
1000 KG

10 KG

5X 1011 PER KG

    J2
                                                          CARBON FIBER PLUME PROFILE
                                      5X 10(
                                                  CARBON FIBER
                                                  COMPOSITE
                                                  STRUCTURE    DOWNRANGE
                                                               SOURCE AREA
                                                                          WIND
                                                                          VELOCITY
                                                                         SETTLING
                                                                         VELOCITY
    CONCENTRATION =
                    f(200)2 (0.5)(60)
                                          c   o
                                    5.3 X 106 F/M3
    EXPOSURE = CONCENTRATION X BURN TIME
                                     F-S
            = (5.3 X 106)(60) = 3.2 X 108
                                      M
                                           fi   F
OSHA ASBESTOS STANDARD :  CONCENTRATION  2x10°-^;


                        EXPOSURE
                                      5.8 x 1010 — PER 8 - HR DAY (CUMULATIVE)
                                               M3
                       Figure 9.   Upper Limit Estimate of Micron Fiber Exposure

-------
                       1 x 107 f/m3 (ceiling concentration)


                 EAS = 5'8 x 10l° f~s/m3 Per 8~nr dav (cumulative)

 The OSHA asbestos exposure level is based on a permissible  concentration level
 of 2 x 106 f/m3 as a time-weighted average over a single 8-hour  period  (2.9 x
 101* sec) .  The exposure level is cumulative since OSHA criteria  permit  similar
 exposures for each successive work day.

      The upper limit of the micron carbon fiber concentration  level  is  only
 about half the permissible OSHA asbestos ceiling concentration level.   Consid-
 eration of factors such as higher wind velocities, longer burn times and
 downrange plume dispersion would lead to values even lower  than  the  OSHA
 asbestos standard.  It appears reasonable to conclude that  the micron fiber
 exposure levels resulting from an aircraft accident would be substantially
 lower than the OSHA standard criteria for asbestos.

 ACKNOWLEDGMENTS

      The support of this research by NASA Langley Research  Center is grate-
 fully acknowledged.  The author would like to express his appreciation  to
 V.  L.  Bell and R.  A.  Pride of NASA Langley for their helpful suggestions,
 encouragement and cooperation toward development of the data base.

 REFERENCES

 1.   Lieberman,  P.  Chovit,  A.  R.  Chovit,  B.  Sussholz,  and H. F. Korman.  Data
     Reduction and Analysis of Graphite Fiber Release Experiments.  (TRW
     Defense and Space Systems Group,  NASA Contract NAS  1-15465.)  NASA
     CR-159032,  1979.

 2.   Pride,  R. A.   Large  Scale Fiber Release and Equipment Exposure Experi-
     ments.   NASA Conference Publication 2119,  1980,  pp.  101-136.

 3.   Occupational Safety  and Health Administration.   General Industry Safety
     and Health  Standards.  OSHA  2206,  Code  of  Federal Regulations, Title 29,
     Part  1910.1001, Revised January 1976.

 4.  Occupational Safety  and Health Administration.  Occupational Exposure to
    Asbestos.   Federal Register, Part  II, 9  October  1975.

 5.  National Institute for Occupational  Safety and Health.  Revised Recom-
    mended Asbestos Standard.  DHEW (NIOSH) Publication No. 77-169, December
     1976.

6.  National Institute for Occupational  Safety and Health.  Criteria for a
    Recommended Standard Occupational  Exposure to  Fibrous Glass.  DHEW
    (NIOSH) Publication No. 77-152, April 1977.
                                      472

-------
 7.   British Advisory Committee on Asbestos of the Health and Safety Commis-
     sion and Ministers.  Volume  1:  Final Report of the Advisory Committee,
     and Volume 2:  Papers Prepared for  the Advisory Committee.  1979.

 8.   Barnet, F.  Robert and Marriner K. Norr.  Carbon Fiber Etching in an
     Oxygen Plasma.   Carbon, Volume 11,  1973, pp. 281-288.

 9.   Barnet, F.  Robert and Marriner K. Norr.  A Three-Dimensional Structural
     Model for  a High Modulus Pan-Based  Carbon Fiber.  Naval Ordnance Labora-
     tory NOLTR 73-154, June 1974.

10.   Sharp, J.  V. and S.  G. Burnay.  High-Voltage Electron Microscopy of
     Internal Defects in  Carbon Fibers.  International Carbon Fibers Confer-
     ence, London, 2-4 February 1971, Paper 10, pp. 68-72.

11.   Johnson, J. W. and D. J. Thome.  Effects of Internal Polymer Flaws on
     Strength of Carbon Fibers Prepared  from Acrylic Precursor.  Carbon,
     Volume 7,  1969,  pp.  659-661.

 12.  Thorne, D. J.   Distribution of Internal Flaws in Acrylic Fibers.
      Journal of Applied  Polymer  Science, Volume  14, 1980, pp. 103-113.

 13.  Bell, Vernon L.  Release of Carbon Fibers from Burning Composites.
      NASA Conference Publication 2119,  1980, pp. 29-57.
                                      473

-------
                         DISCUSSION ON GRAPHITE FIBERS

REMARK     (Dr.  Corn):   I am associated with the John Hopkins University.  My
           comments  are  relative to the last presentation which  I  found  an
           interesting diversion in science  fiction  until you invoked  the
           OSHA  standards for asbestos.   You must be aware, Dr.  Sussholz, that
           the OSHA  standard is  one of using a surrogate for the total number
           of asbestos fibers present.  It is implicit  that the  standard
           sample should be  used and analyzed in a standard manner.  You
           sampled in a  nonstandard grossly  inefficient manner for precisely
           the inhalable particles  associated with asbestos risk.  You cannot
           expect to capture those  by a sedimentation method or  a  sticky
           paper method.   You then  superimposed upon that extrapolation  of
           values what I would call "finagle factors" and an interesting
           construct, all of which  I am perfectly willing to listen  to.  But
           do not then compare that to a  meaningful  standard for the assess-
           ment  of risk  to inhalation of  fibers.  I  would submit here  that the
           analysis  is just  totally incorrect.

REMARK     (Dr.  Sussholz):   I guess my concluding remarks, which attempted to
           reflect the uncertainties and  the application of the  results  with
           referencej to  the  general areas of interest here, were insufficient
           to allay//the  fears of this gentlemen.  I  cannot disagree  with any
           of the comments you made;, you  are free to your own opinion.   This
           was the best  we could do under the circumstances.  It turned  out
           to be the first study of its nature.   And in any manner that
           additional work can be supported  in any way  anywhere  at all,  that
           is a  wonderful idea.

QUESTION   (Mr.  Wagner):   I  am from Dupont.   Dr.  Sussholz, do you  have any
           data  on the number of micron size particles  generated in  machining
           or cutting of a carbon fiber reinforced composite?

ANSWER:    (Dr.  Sussholz):   Not  that I am aware of.  We do not have  data of
           any nature along  those lines,  and I  am not aware of a study that
           has been  performed where this  type of information was of  prime
           interest.
                                    474

-------
            CROSS-SECTIONAL MEDICAL STUDY OF WOLLASTONITE WORKERS

                                       by

          Dr. Brian Boehlecke, Dr.  D.M. Shasby,  Mr. M.R. Petersen,
                    Dr. T.K. Hodous, and Dr. J.A. Merchant*
           National Institute  for Occupational Safety and Health
                        Morgantown,  West Virginia 26505
                                     ABSTRACT

   Wollastonite  is a fibrous monocalcium silicate with widespread use in ceramics
   and as a substitute for asbestos.   Workers at the only U.S. wollastonite mine
   and mill were studied with spirometry using air and 80% helium-20% 02, chest
   x-ray, physical examination, and respiratory questionnaire.  Diffusing capacity
   of the lung (D,ro) was measured in 23 workers with over 15 years' exposure.
   Overall, 104  men(72% of all those with at least 1 year of exposure) were stud-
   ied.  Air samples were collected at the work site on Millipore filters and fiber
   counts performed with phase contrast microscopy.  An exposure index was calcu-
   lated by multiplying mean count of fibers (greater than 5 micrometers in length)
   per cc x years of work.

   Symptoms of chronic bronchitis were present in 23% of smokers and ex-smokers
   and in 9% of non-smokers.  However, there was no association of prevalence of
   bronchitis with increasing exposure index.  A reduction in forced vital capaci-
   ty (FVC) below the predicted range was found in only  1 worker.  Although 20%
   of smokers and ex-smokers had a forced expired volume in  1 second (FEV^) less
   than 70% of FVC, no significant correlation of obstructive impairment or forced
   expiratory flow at 50% of vital capacity with exposure index was found for air
   or helium-02 spirometry.  One subject who has polycythemia vera had an abnormal
   DTr_.  Four men without other abnormalities had  chest x-rays showing  Category  1,
   type q, rounded opacities.  No irregular opacities or pleural plaques were noted.
   Five workers, all current or past smokers,  had crepitations in the  lungs, not
   associated with x-ray changes.  Wollastonite  is  similar  to asbestos,  but we were
   unable to demonstrate the usual stigmata of asbestos  exposure.   Because only 36%
   of men studied had over  15 years' exposure,  further  followup  is  needed  to deter-
   mine if wollastonite is  truly less hazardous  than asbestos.
*Presented by Dr. Brian Boehlecke.   This  study may be  found in Dust and Disease,
"Respiratory Morbidity of Workers Exposed to Wollastonite through Mining and
Milling."  John Dement and Richard Lemmens (Eds.), Pathotox Publishers, 2405
Bond  Street, Park Forest South,  IL 60466, (1979) p.  251-256.

                                         475

-------
                          DISCUSSION ON WOLLASTONITE

REMARK    (Mr. Clifton):   I  am from the U.S.  Bureau of Mines.

          I  see you  are  looking for substitutes  for asbestos all over  the place
          and it  is  very nice  to find  one  that has  many  of  the  same properties
          as asbestos with no  apparent health effects.   A word  of caution,
          though.  Some  of these substitute materials are very  finite  resources
          and reserves,  which  means that if they were purported to replace
          asbestos in large  areas,  the cost could go up  astronomically.  Wol-
          lastonite  happens  to be one  with very  small reserves  and resources.

QUESTION  (Dr. Gross):   I  am from the  Industrial Health  Foundation.

          While you  were talking I  looked  at  a graph of  the relationship of alveolar
          deposition, that is  deposition in the  air spaces  against the diameter
          and length of  the  fiber.   As I understand it,  the average wollastonite
          fiber was  in excess  of 2  micrometers in diameter, is  that correct?

ANSWER    (Dr. Boehlecke) :  No.   Two and a half  micrometers in  length, and
          0.22 micrometers in  diameter.

REMARK    (Dr. Gross):   In that case,  I do not have any  information on that.  But
          if it had  been 2 micrometers in diameter,  it would have had  a deposi-
          tion in the air  space of  only 2 percent.

REMARK    (Dr. Boehlecke):   No,  it  is  0.22.
                                      476

-------
                    ENDEMIC PLEURAL  DISEASE IN RELATION TO
                               ZEOLITE EXPOSURE

                                       by
                            I
                             Arthur  N.  Rohl,  Ph.D.
                     Mount Sinai School of  Medicine of the
                          City University of  New York
                              New York, New York
                                    ABSTRACT

    Pleural mesothelioma, lung cancer, pleural and parenctyymal fibrosis appear to
    be  endemic in an agricultural area of Cappadocia, Turkey.  Initial observations
    Indicate that asbestos does not occur nor is it used.  However,  fibrous zeolite
    minerals appear to be widely distributed there. The verification of this
    supposition may provide information  on a troubling and unresolved public
    health question.  With the recognition of significant hazards associated with
    exposure to asbestos, caution has been suggested on the basis that substitute
    commercial fibers may have similar biological activity.  This concern is rein-
    forced by Stanton's hypothesis that  the toxlcity of inorganic fibers depends
    more on their shape and size than on physical-chemical factors.  Human  ex-
    perience bearing on the question for evaluation has been heretofor lacking.
    The affected area was visited and a  large number and variety of  environmental
    samples, as well as lung tissue of individuals with mesothelioma and other
    thoracic disease were collected.  These samples are being analyzed to estab-
    lish the mineral assemblages present to permit correlation of observed dis-
    ease with microparticulate exposures which may have occurred.


     More than 50 cases of pleural mesothelioma have been  reported during
the period from 1974-78 in a relatively  small area of Turkey, centered in and
around the villages of Karain and TuzkBy,  in the province  of  Cappadocia.  The
incidence of malignant pleural mesothelioma in this area for  exceeds any rate
for any population not known to  be asbestos-exposed.  Moreover,  calcified
plaques, pleural thickening and  parenchymal scarring are also prevalent in
these populations.  Plaques and  scarring are often stigmata of  exposure to
asbestos, leading to mesothelioma.   No outcroppings of asbestos-containing
rocks, nor asbestos mines or industries,  are known to exist in this area.
However, another group of silicate minerals is present.  This group of min-
erals is called zeolites and it  Includes fibrous types, having fiber dimen-
sions similar  to some asbestos  fibers.   The area of Karain and Tuzkoy  is
covered with volcanic tuffs, which are  altered in places  to form a range  of
zeolite minerals.  The volcanic  tuff consists principally of  glass fragments
(including glass fibers), quartz, plagioclase feldspar  and pyroxene minerals.
In addition to zeolites, other  alteration products such as montmorillonite,
cristobalite and tridymite are  found.   The tuffs in this  area of Turkey are
                                      477

-------
 generally soft and friable and are subject to wind erosion.   The tuff  building
 stones are hand-cut from local quarries located in hills and cliffs  adjacent
 to the different villages for construction purposes.   A large proportion  of the
 houses in Karain are actually caves, excavated by hand from  the soft tuffaceous
 rock.   The village of Karain itself abuts the steep valley wall which  overlooks
 the town.  In addition to houses,  a number of holes and caves have been ex-
 cavated in the nearby outcropping  of tuff for use as  animal  pens, food storage
 areas, and fodder storage areas.   Pigeon excrement, the. only fertilizer used,
 is collected by villagers from the nest-holes in the  tuff.   In the homes, and in
 the excavated caves, and in agricultural pursuits, constant  contact  is made with
 settled dusts, soils and rock surfaces.  The floors of the homes tend  to  be the
 soil surface.  Also, in many homes, the use of pulverized white soil,  locally
 collected for whitewash is also common.  The roads in the area are for the
 most part unpaved.  Winds, vehicular traffic, and other activities in  this
 semiarid climate results in the generation of large amounts  of airborne dust.
 Agriculture and animal husbandry are virtually the only occupations.   The
 effect of these circumstances is to expose the populations of the villages to
 high levels of airborne dust, originating from the host rock, throughout  their
 entire lives.  While some villages have the appearance of being dustier than
 others, the observed differences in levels of pleural diseases among the  villages
 in the area may be the result of either differences in the kinds and amounts of
 dust exposures, or both.  The mineralogical characterization, both quantitative
 and qualitative, of these materials affords an important foundation  for the eval-
 uation of the biological problems.

     With the cooperation of the Turkish scientists studying the Cappadocia
 situation,  we visited the area and obtained a large number and variety of rock
 and environmental samples such as  house and road dust,  local whitewash, per-
 tinent geological samples, building stone as well as  lung tissue of  individuals
 with mesothelioma and other thoracic disease.  These  samples are being analyzed
 to establish the exact mineral assemblages present and to permit correlation of
 observed disease with dust exposures which may have occurred.

     The incidence of mesothelioma is of particular interest since this
 cancer has  been considered to be a "marker disease" for asbestos exposure.  Re-
 cent studies suggest that most mesotheliomas (80-95 percent) can be  traced to
 asbestos exposure.   (1)  In the village of Karain, in Cappadocia, with a  total
 population  of 604,  there were 11 deaths due to pleural mesothelioma  of a  total
 of  18  in 1974.   In the previous five years,  25 pleural mesotheliomas were re-
 ported  from the same village.   (2) On the basis of a  study carried out in a
 nearby  village,  Tuzkoy, with a population of about 3,000,  it was found that the
 incidence of pleural mesothelioma  is at least 6.5 patients per year, or about
 one  thousand times  more than expected.   (3)  It is of  interest to note  that
 these data were accumulated by the Chest Service of a large  Turkish  medical
 center,  so  that peritoneal mesothelioma may remain largely unreported, although
 it  is known  to  have occurred.   It  is possible that even this extraordinary
 finding may  be  significantly underestimating the true incidence of mesothelioma
because  of  the  remoteness of the area and the general lack of medical  services
 in the  region.


                                      478

-------
     The results of this study may be expected to provide information re-
garding the validity of the Stanton hypothesis.   (4,5,6)  Stanton suggested,
based on experimental observations, that the exposure of  animals to fibrous
materials produces greater cancer risk than the exposure  to identical mater-
ials which are non-fibrous.  For example,  the intrapleural injection of fibrous
materials of diverse types and size distributions into animals produces mal-
ignant tumors significantly related to fiber shape and a  narrow size range of
fibers.  It is stated that the "simplist incriminating feature for both car-
cinogenesis and fibrogenesis seems to be a durable fibrous shape, perhaps in a
narrow size range.  (6) Stanton observed that long, thin  fibers produced pro-
portionally more mesotheliomas when implanted in the rat.  In addition, the
experiments of Pott and Friedrichs, (7), and Pott, Huth and Friedrichs (8)
indicated that the carcinogenic (mesothelioma) potency of a mineral depended
upon shape factors, the fibrous forms tending to be more  carcinogenic.  There-
fore it appears reasonable that the focus for search of a physical etiologic
agent in association with mesothelioma should fall on mineral fiber.  For
one fiber, asbestos, documentation concerning the relation to mesothelioma is
extensive.  In Turkey, since endemic mesothelioma and other pleural diseases
occur without apparent asbestos exposure,  other mineral fibers, possibly fib-
rous zeolites, may be implicated.  An important objective will be to confirm
the alleged absence of asbestos in environmental samples.  Since there are no
asbestos mines or mills and since there is no use of commercial asbestos prod-
ucts by the villagers, it has been argued that asbestos is not the etiologic
agent.  This argument is based on the speculation that the geological nature
and history of the area are highly unfavorable for the occurrence of asbestos
deposits, commercial or otherwise.  However, Cappadocia covers an area of
over 1,500 square kilometers, mostly remote and inaccessible.  The geology is
highly complex and has not been studied in sufficient detail to fully exclude
the possibility that asbestos minerals may occur in the area.  They may or may
not occur in or near the villages.  They may be exogeneous, brought from dis-
tant sources.  For example, it is common practice in the  region for the villagers
to stucco or whitewash their dwellings for hygienic and esthetic purposes.
Preparation, application and removal of the whitewash produces visable dust, and
surface erosion of the whitewash may add to this dust.  Each village obtains its
own supply of whitewash from various, unknown sources.  Asbestos minerals may
occur with some types of light-colored rocks, such as metamorphosed limestones.


ZEOLITES

     Zeolites are hydrated aluminum silicates, with alkaline metal and al-
kaline earths substituting within the framework structure.  The water of hydra-
tion is both variable and reversible, and cations may readily  substitute within
the structure.  The corners of the silica tetrahedron are shared, producing  a
three-dimensional lattice, and substitution of aluminum  for  silicon in the
tetrahedra produces a charge imbalance imparting  a negative  charge  to  the
structure.  About 40 naturally-occurring zeolites have been  described  and over
100 synthetic zeolites have been made for industrial applications.  The  latter
are commonly known by their commercial designation as "molecular selves."
                                      479

-------
The  physical-chemical properties  of  the  zeolite minerals are extremely var-
iable.   The mineral can easily be dehydrated  and  rehydrated; cations easily
substitute  and re-enter the structure; the  ion exchange capacity and the ability
to absorb various  gases is  enormous;  an  increase  in the silicon to aluminum
ratio decreases cation substitution,  but increases  acid resistance and thermal
stability;  the increase in  silicon to aluminum ratios  decreases cell dimen-
sions and external pore diameters, further  altering the nature of molecular
interaction.   The  changes in physical-chemical properties  of the zeolite min-
erals may affect their biological potential.

     Zeolites  naturally form by alteration of  volcanic  ash, which is
essentially glass.   This alteration  may  occur either in saline alkaline lake
waters,  or  in areas where ground  water is present and  may  percolate through
the  sediments.   Alkalies present  in  the  volcanic  debris are dissolved and
chemically  react with the glass to form  zeolite minerals.  Zeolites naturally
occur in volcanic  sediments throughout the  United States.  (9) Some of the
zeolite  minerals are extraordinarily abundant and widespread.  Karain and
TuzkHy pose the question whether  natural zeolite  minerals  found in the rocks
and  soils of  Turkey,  or in  other  areas of the world, possess the biological
potential to  induce mesothelioma  and other  disease.

REFERENCES

1.   Cochrane,  J.C.  and Webster, I.  Mesothelioma  in relation to asbestos fibre
     exposure;  a review of 70 serial  cases.  South African  Med. Jour. 1978;
     54:279-281.

2.   Baris,  Y.I,  Sahin,  A.A.,  Ozemi, M.,  Kerse, I.,  Ozen, E., Kolacan, B., Altinors,
     M. and  Goktepeli,  A.  An outbreak of pleural  mesothelioma and chronic fibros-
     ing  pleurisy in the village of Karain/Urgup in  Anatolia.  Thorax 1978; 33:2:
     181-192.

3.   Artvinli, M. and Baris,  Y.I.  Malignant  mesotheliomas in a small village in
     the  Anatolian  region of Turkey: An epidemiclogic study.  Jour. Natl. Cancer
     Inst. 1979:63:17-22.

4.   Stanton, F.  F.  and Wrench,  C.  Mechanisms  of mesothelioma induction with
     asbestos and fibrous glass. J. Natl.  Cancer Inst.  1972:48:8:797-821.

5.   Stanton, F.F.,  Layard,  M.,  Tegeris,  A., Miller,  E., May, M. and Kent, E.
     Carcinogenicity of  fibrous  glass:  Pleural response in the rat in relation
     to fiber dimension.  J.  Nat.  Cancer  Inst.  1977;58:3:587-603.

6.   Stanton, F.F. and Wrench, C.  Mechanisms of mesothelioma induction with
    asbestos and fibrous glass.   J. Natl. Cancer  Inst. 1972;48:3:815.

7.  Pott, F. and Friedrichs,  K.H.  Tumoren der Ratte nach i.-p Injektion faser-
    formiger Staube.  Naturwissenschaften 1972; 59:318.
                                     480

-------
8.  Pott, F., Huth, F. and Friedrichs, K.H.   Tumorogenic effects of fibrous dusts
    in experimental animals.   Environ. Health Perspectives 1974;9:313-315.

9.  Sand, L.B. and Mumpton, F.A.  Natural zeolites,  occurrences, properties, use.
    Pergamon Press, N.T.C. p.  546.
                                      481

-------
                        DISCUSSION ON ZEOLITES IN TURKEY

 QUESTION  (Dr. Rowe):  Dr. Rohl, the mesothelloma that is prevalent in this
           area of Turkey, is it all pleural mesothelioma or is there also
           peritoneal mesothelioma?

 ANSWER    (Dr. Rohl):  It is virtually all pleural mesothelioma.   There are
           one or two cases of peritoneal mesothelioma, but these  may have been
           largely overlooked because it is a remote, rural area of Turkey.
           Modern medical services are practically unavailable. The only people
           who come to Dr. Baris' chest clinic at Haceteppe University are those
           with serious pleural disease.  Those with other diseases may go
           unobserved.

 QUESTION  (Mr. Dickinson):  Yesterday, we heard that if you used  asbestos cement
           on roofing tiles and then collected water in cisterns you tended to
           get asbestos fibers at times.  You mentioned having taken samples of
           house dust and road dust as well as white wash.   Since  this is a
           desert area, essentially, water is a very scarce commodity, I would
           hypothesize that probably villages would tend to have one water
           source from which they would all drink.   My question is whether the
           same water source was available for all the villages or whether in
           effect each one has a separate source and may be one of them was
           contaminated and the others not?

 ANSWER    (Dr. Rohl):   That was investigated.  Although there are two water
           sources,  one well is the major source for the entire village of Karain,
           and no agents were found in the water.  It was analyzed for both
           inorganic and organic contamination which might  be responsible.
           Although  asbestos fibers were found by one investigator this has
           not yet been confirmed.

 REMARK    (Dr. Wiley):   I am from the University of Maryland.   I  would like to
           stand behind what Mac Ross has said.   I  think that the  evidence is
           not at all conclusive that zeolites are  the cause of the mesothe-
           liomas.   I would just like to point out  that the sizes  that you
           mentioned,  less than 0.25 microns in diameter and 3 microns in
           length, are  almost identical to the sizes of wollastonite particles
           that were presented in the previous study.   So that if  indeed it is
           a size and shape factor  that is in the disease,  we have a real
           contradiction in the evidence here.

REMARK     (Dr.  Rohl):   We have a whole string of ifs,  ands, or buts.   No one
           said it is a  simple question.   It is  going to take a lot of time.
           It  is  a very  complicated  analytical matter,  and  the interpretation
           of  the results  will also  be  very intricate.

REMARK     (Dr. Langer):   I wonder if I  can add  to  this discussion.   Perhaps
           some other data will help  shed light  on  this subject.   Mt.  Sinai
          has  a number  of ongoing studies  in our Laboratory which appear to
           indicate the  following: fibrous  erionite  has produced tumors
           (mesotheliomas)  in  the bellies of mice.   Mordenite fiber has not as

                                     482

-------
          yet.  It produces pronounced scarring.   This might have been predicted
          by their aluminum: silicon ratios.  Some species of fibrous zeolites
          appear to be fibrogens, some possible carcinogens.  Perhaps not all
          of the zeolite minerals will be shown to be active.  We need more
          time and experiments to verify this.

          We have also completed studies concerning the hemolytic potential of
          these various materials.  Again, the aluminum: silicon ratio has some
          correlation with hemolytic potency.   High silicon containing zeolites
          are cytotoxic.  These compounds are  membrane active.  Some of these
          materials, because of their extraordinary cytotoxity, will not allow
          cells to live long enough to undergo mutation and transformation.
          Cancer will not be the outcome for these exposures.

          There is a tremendous set of data that has been collected by the
          IARC consulting group in Wales  (PRU-Llandough):  Wagner confirmed
          the Turkish mesotheliomas; Fred Pooley confirmed the presence of
          zeolite mineral species; Peter Elmes confirmed the clinical diseases;
          Joe Skidmore, probably one of the best "dust11 men in the world, went
          there and performed environmental measurements.  When all of these
          data were collected and looked at as a body of knowledge, the follow-
          ing was found:(1) there occurs bonafide mesotheliomas; (2) in the
          environment there exists a series of fibrous minerals.  They are
          zeolites; (3) the environmental measurements suggest the amount of
          fiber that is actually in air is very small.  These fibers are again
          zeolites.  Yet, what is the agent that is responsible for the meso-  •
          thelioma?  Can small amounts of zeolite fiber produce mesothelioma?
          We have done some work on the stucco that is used to whitewash the
          insides of the Karain houses.   They are derived from many sources of
          rock and some of these sources may contain other mineral fibers.
          These may be agents of disease  as well.

          There are other possibilities as well: I think it is much too early
          for us to dismiss the possibility that a subspecies of erionite fiber
          may produce mesothelioma; there may be some asbestos in the area.

QUESTION  (Mr. Mill):  I am from the Cabot Corporation.  A common alteration
          product of volcanic tuff is cristobalite which has biologic activity.
          Was there any cristobalite in this tuff to your knowledge?

ANSWER    (Dr. Rohl):  Yes.  Cristobalite was described in some of the samples.

QUESTION  (Mr. Mill):  And I would like to ask another question that is not about
          Turkey.  There is a very common zeolite mineral which to my knowledge
          is not fibrous, in the American West, and that is  clinoptilolite,
          which is beginning to enjoy some commercial exploitation.  Does any-
          one know if this has been found to  cause health problems?

ANSWER    (Dr. Rohl):  No, I do not think that has been studied with reference to
          clinoptilolite.  clinoptilolite does occur  in the Turkish tuffs.
                                      483

-------
REMARK     (Dr. Langer):  I would like to add to this.  We have looked at
           clinoptilolite in our membrane system and it is very active.  It has
           a "hemolytic" index or hemolytic potency which is almost equal to that
           of quartz.

REMARK     (Mr. Mill):  Well, I'd like to make one other comment.  Clinoptilolite
           apparently is nonfibrous, and I find it difficult to accept this
           Stanton hypothesis, as it is mentioned in the abstract, that it is
           the geometry of these particles that determine their problems.

QUESTION   (Mr. Merryman) :  I am from the Dupont Company.  I would like to ask
           Dr. Langer what was the difference between the zeolite minerals
           that did and di'd not produce mesotheliomas or tumors in the lab-
           oratory different in shape in addition to their difference in chem-
           ical structure?

ANSWER     (Dr. Langer):  I am from Mt. Sinai.  There are marked differences
          between erionite and mordenite.  Erionite tends to be more "asbesti-
           form", if I can use that term, than mordenite.  Mordenite tends to
           occur as long, flat, bladed crystals.  If we were to look at its size
           distribution characteristics, and compare it with erionite, erionite
          would be more like an amphibole asbestos mineral, like amosite or
           crocidolite, whereas the mordenite would be more like anthophyllite.
           I add that amosite and crocidolite have produced mesotheliomas in
          human populations whereas anthophyllite has not.

          Mordenite tends to have less aluminum in the structure; therefore it
           has less of the alkaline cations substituting in the structure.  The
           erionite tends to interact more with polar compounds (this has been
           described in the literature extensively).  Mordenite tends to be
           more a silicon-rich, more "siliceous" if you like, and tends to
           have chemistry more like quartz, or like the silica polymorphs.
           Mordenite produces scarring in animals; erionite produces cancer.

QUESTION   (Mr. Merryman):  I gather then, that there is both a surface size
           and a chemical effect possible.  Can you expand on that?  Does
           there tend to be any data that indicate that you can have a chemical
           effect independent of the size and shape effect?

ANSWER     (Dr. Langer):  Absolutely.  The Stanton hypothesis suggests that
           any fibrous inorganic dust which reaches the mesothelial surface
          will induce a tumor response.  Mesothelioma or fibrosarcoma may be
           produced regardless of the chemistry and of the composition of the
           fiber.  Last night we had an extensive discussion of this in the
          Talc Session.  We talked about different mineral fibers and whether
           or not each possessed certain inherent physical-chemical charac-
          teristics which would distinguish among them in terms of biological
          activity.   I believe it is simplistic to assume that because a
          material is  a "fiber" that there is some extraordinary power to
                                      484

-------
          induce tumors.   I do not think that is  so.   For example,  we know
          chrysotile degrades readily while in biological residence,  and
          amphibole fibers do not.  Amphibole fibers  deliver a dose to target
          tissue which is the number of particles multiplied by the unit time
          in residence in those tissues.   Amphibole unit  dose delivered to tissue
          is therefore longer than for an equivalent  amount  of chrysotile.
          Investigators have studied the activity of  degraded chrysotile and
          observed a markedly decrease of mesothelioma potency.  Therefore, both
          a changed, surface character and a degradation process both account for
          markedly decreased carcinogenicity.   What we were  seeing  is that
          obviously fiber morphology is useful in terms in inhalation potential,
          in terms of penetrating the airways, in terms of deposition at the
          alveolar site.   But once it is delivered to the target tissue, the
          response would be dependent upon the characteristics of the material
          Itself.

QUESTION  (Dr. Reeves):  I am from Wayne State University.   I have  yet to hear a
          substantial answer to Malcolm Ross1  comment, specifically the dif-
          ference between these two communities that  seem to have the same
          geological structure and the same availability  of  dust, and yet
          the startling difference in mesothelioma incidence.  I think that
          might be quite significant.  I also looked  at your mortality or
          morbidity data.  Am I correct in remembering that  there were seven
          new cases of mesothelioma in a town of  3,000 every year?

ANSWER    (Dr. Rohl):  Seven.

QUESTION  (Dr. Reeves):  Seven cases.  Now over a lifetime that would amount to
          something like 15 percent of the population, perhaps 20 percent of
          the population coming down with the single  disease of mesothelioma.
          Now this is such a startling incidence  that I just cannot understand
          that this could have remained undetected throughout history.  This
          is one of the oldest inhabited areas of the world.

ANSWER    (Dr. Rohl):  And one of the most primitive, too.

REMARK    (Dr. Reeves):  No, it was not; today it is, but at a time of Alexander
          the Great and so forth —

REMARK    (Dr. Rohl):  They did not have pathologists then.

REMARK    (Dr. Reeves):  These were the most cultured regions  of the world.
          I would have expected someone like Hippocrates to notice.

REMARK    (Dr. Rohl):  Maybe he did, but we have no record of  it.

REMARK    (Dr. Langer):  Dr. Reeves, I believe the name Karain comes  from the
          Turkish which means "pain in the belly".  Karain has a peculiar folk
          legend which states that "anyone from Karain who develops  a pain in
          the side, soon his shoulder drops and he dies."  This is the classical
          clinical syndrome for mesothelioma.  But you are quite correct.  It
          has been noted for a very long time  that people from this  area died

                                      485

-------
           with these strange chest maladies.   And you are also  correct,  that
           the incidence is quite extraordinary.

           We find no differences between our  data and those  of  Fred Mumpton
           from SUNY: the same fibrous zeolites are present in the  soils  and
           dusts of villages with mesothelioma, and those without mesothelioma.
           Again, it may be a special subspecies  of erionite  or  the presence of
           other fibrous minerals of great biological activity.  Yet, we  are
           still examining these specimens very carefully. X-ray diffraction
           shows the same basic mineral population in both localities.  But
           there may be some specific fiber that  occurs in Karain that  is
           different from those which occur elsewhere.

           If you take "active sites" on the surface of zeolite  minerals  and you
           block them with certain cationic species, I can assure you they will
           not be biologically active.  But those of you who  know zeolites, who
           know how active these materials are, how well it binds with  various
           cations, will understand how active these minerals can be.   These
           are wonderful compounds.  However,  if  you inhale these particles,
           their activity does not stop.   The  activity may go on, degrading
           proteins and denaturing proteins in young tissue.

 QUESTION  (Mr.  Wideland):  I am a geologist from the University of Minnesota.
           I  have a medical question which I ask  out of ignorance.  Has your
           laboratory or any other laboratories attempted to  identify the
           mineral species in lung tissue of these people who have  died from
           mesothelioma?

 ANSWER     (Dr.  Rohl):   We are working on that.  We collected lung  tissues from
           patients of Dr. Harris'  with mesotheliomas and we  are investigating
           the types and amounts of the minerals  in those tissues.  That  will
           be a very important factor in  interpreting the results.

 QUESTION  (Mr.  Wideland):  In my casual  reading  of the medical  literature there
           does not seem to be a discussion of the possibility of ever  locating
           a  specific fiber that you could pin down to having triggered a
           carcinoma.   Is  that out  of the range of possibilities?

ANSWER     (Dr.  Rohl):   Well,  identifying likely  candidates would be an important
           first step.   After the likely  candidate is identified, then  further
           animal experimentation would have to be done to find  out if  it does
           produce the  same disease.

QUESTION   (Mr.  Ross):   A  couple of points.  First,  I do not  have the ref-
           erence,  but  I believe that Pooley has  identified fibrous zeolites.
           I have  to  refresh my memory, but I  believe Karain, a  very isolated
           town,  is the  town with a very~Tiigh  incidence of mesothelioma",  of~
           five or  six a year.   TuzkSy has much fewer cases.  I  do  not  have the
           number, but  Tuzkoy has much fewer mesotheliomas than  Karain  which is
          not quite  as  isolated a  city as  Karain is.   But one of the things
           that  intrigued  me in the Baris reports,  is that in all the deaths he
                                      486

-------
          reported not one,  I believe,  was  lung cancer.   The males smoked.
          Now If you look at asbestos-related  disease  you see a very high
          correlation in a cohort  mesothelioma with  lung  cancer.   With
          asbestos workers—you do not  find them all dying just of meso-
          thelioma or all dying just of lung cancer.   It  surprises me that
          there was no reported lung cancer in this  group of individuals.
          I defer to the medical people,  but would this suggest a hereditary
          implication?

          Going back to what I said, it is  all very  fine  to do some good
          straight science on this, but when you do  a  little bit of science
          and very poor science and then you rush out  to  an industry and say
          you are going to kill the workers because  you are using zeolites
          in your refining process, when that  zeolite  happens to be a synthetic
          zeolite that is not fibrous,  the  whole work  force is put into a
          paranoia.  Zeolites are  a very large mineral group.   And most zeolites
          are not fibrous.  One person  got  a hold of a newspaper article
          and said we can not have the  missile sites in Nevada because it will
          dig up the ground and all the zeolites will  come out.  So the whole
          southwest United States  is full of zeolites  which I call evil rocks.
          And so we take a very preliminary scientific investigation and scare
          half the United States.   I do not think that is being very wise,
          particularly when the zeolite industry is  out here, and 90 percent
          of the industry is out for cleaning  up our environment.

REMARK    (Dr. Rohl):  One thing that I forgot to mention, there is lung
          cancer in both Karain and Tuzkoy. The men in Turkey smoke; both
          populations smoke.  The  women do  not.  But there is no difference in
          the rates of mesotheliomas among  men and women.
                                      487

-------
                  CHEMICAL DETOXIFICATION OF ASBESTOS FIBERS

                                       by

                            Earl  S.  Flowers, Ph.D.
                          Flow General Incorporated
                                McLean, Virginia
                                    ABSTRACT

    Exposure to asbestos materials is associated with a variety of biologic re-
    sponses which include ferruginous body formation, chronic flbrosing processes,
    and development of cancers.   Formation of a ferruginous body is an  early re-
    sponse of tissues to asbestos, and a variety of  such bodies involving deposi-
    tion of iron containing materials on the fiber have been described.  One type
    of ferruginous body is formed by the deposition  of inorganic iron on the fiber
    surface.  Acting on the premise that the addition of ferric oxides  or other
    metal oxides to asbestos would detoxify silicates and other toxic sites on the
    fiber, several metal micelle forms of asbestos,  including chrysotile, amosite,
    crocidolite, and anthophyllite have been prepared.  Biologic testing of iron
    micelle forms of chrysotile and amosite show that the treatment with iron salts
    decreases the cytotoxity of these forms of asbestos when compared with untreated
    materials.  The treatment of chrysotile with an  iron salt also decreases hemo-
    lytic activity and adverse effects on membrane permeability of cells.  Testing
    of the iron treated chrysotile in a variety of applications using Grades ranging
    from AAA to 7 RF 99 in quality indicates that the treated asbestos  retains de-
    sirable physical properties and can substitute for asbestos in all  its current
    applications.  The chemical treatment has been extended to show that metal oxides
    of cobalt, chromium, manganese, aluminum, and copper also add to an asbestos
    fiber.
     Exposure to asbestos  in the environment  is associated with increased  risk of
developing chronic fibrosis  in the lungs and  two forms of cancer, bronchiogenic
carcinoma  and mesothelioma.   Asbestos has been characterized  as an unavoidably
unsafe material, but its desirable physical properties including heat resistance,
reinforcing strength, chemical resistance, flow characterization and versatility
in applications including  cements, boards, papers, textiles,  friction materials
and numerous other products  has supported the continued and essential use  of
asbestos minerals.  Considerable efforts have been made to find substitutes for
the use of asbestos in its varied applications, but these efforts have met with
limited success.  Invariably, proposed substitutes do not measure up to  the use
of asbestos itself, or there are considerable costs that make use of the substi-


                                        489

-------
 tute prohibitive.  One approach to this issue is to develop a substitute by
 chemical detoxification of asbestos fibers.  The objectives of this report are
 to discuss the basis for chemical detoxification of the asbestos surface, to
 present initial results of in vitro tests of treated materials, and to discuss
 the effects of chemical treatment on the desirable attributes of asbestos.

      The most hazardous asbestos fibers are those characterized as being deposi-
 ted in the alveoli.  Once deposited at critical tissue sites, asbestos produces •
 a variety of responses including irritation of cells and tissues, increased
 oxygen consumption, formation of ferruginous bodies, chronic fibrosis, an in-
 creased risk of bronchiogenic carcinoma, and an increased risk of developing
 mesothelioma.  In 1974,1 I developed a hypothesis that these various responses
 to asbestos were related.  Silicate groups on the asbestos surface were charac- .
 terized as active sites for formation of ferruginous deposits, and the leaching
 of magnesium ions from the surface was identified as being involved in some of
 the toxic effects.

      Figure 1, adapted from my paper in 1974,l summarizes the hypothesis concern-
 ing the relationship between exposure to asbestos, ferruginous body formation,
 chronic fibrosing processes, and carcinomas.  A sequence of dependent events
 is thought to occur leading to increasingly adverse toxic effects.  The under-
 lying mechanisms are depicted as involving two independent pathways.  In one
 pathway,  after phagocytosis and fiber encapsulation, a ferruginous body is
 formed consisting primarily of substances containing ferric oxides, such as
 ferritin, hemosiderin,  or inorganic ferric hydroxides.   The driving force for
 deposition of ferric containing species is the presence of electronegative sites
 produced  by formation of hydrated silicates on the asbestos surface.  The re-
 moval of  ferric ions in the formation of a ferruginous body requires the oxi-
 dation of ferrous ions  to replace the ferric ions in solutions and to reestab-
 lish redox equilibrium.  This results in an increased glycolysis as indicated
 by increased oxygen consumption by tissues exposed to asbestos.  Excessive
 glycolysis leads to release of a fibrogenic factor characterized by Heppleston2
 as possibly a galactan.  This factor induces an increased rynthesis of elastic
 fibers such as collagen at tissues which are remote from the site of deposition
 of the asbestos fiber.

      In Figure 2, the synthesis of collagen requires an oxidation of proline in
 protocollagen by molecular oxygen with reduction by a reducing cofactor to form
 hydroxyproline.   This converts protocollagen to a more hydrophilic collagen
 and frees the RNA-template for continued production of protocollagen.   Thus,
 continued release of a  fibrogenic factor induced by increased glycolysis stimu-
 lates  a chronic  production of fibrous protein or chronic fibrosing processes.

      In Figure 1, the significance of the chronic fibrosing processes is inhibi-
 tion of reductases leading to asbestos acting as a cocarcinogen in producing bron-
 chiogenic carcinoma. This decrease in the availability of reducing cofactors
 favors  production of stable epoxides  derived from toxic products of combustion,
 synthetic  toxins  or  natural products.  Another  cocarcinogenic mechanism for
 producing  an  increased  risk of carcinoma is the disruption of membranes by the
mechanical irritation of  cells and  tissues.   The resulting increase in membrane
permeability would provide  greater  access  for carcinogens and other toxic agents.
Finaily, another  cocarcinogenic mechanism is by transport of a carcinogenic

                                      490

-------
       Increased
       Giycolysls
\O
      Release of a
       Fibrogenic
        Factor
       Collagen
      Synthesis
                                        Inhalation of
                                       Asbestos Ousts
                                                Leaching of
                                                Magnesium
                                                   Ions
                            rH  OtoA
                                Transition
                                   Phagocytosis & Fiber
                                      Encapsulation
                Ferruginous
                 Body Forms
         Disrupted
        Membranes
                               Easier Access for
                                 Carcinogens
Inhibition of
 Reductases
Carcinoma
                       Destruction of Normal
                         Mesothelial Cells
                                                                               Mesothelioma
Carcinogen
 Transport
                                            Figure I.

-------
VO
            Proline
Proline + Amino Acids
                                      I nhalation of Asbestos
                                       Increased Glycolysls
                                           Release of a
                                        Flbrogenic Factor
a-Ketoglutaric
    Acid
                              Ri bo so ma! Bound
                                Protocollagen
*-
.A
Protocollagen
Hydroxylase
\
t
                     ^Collagen	^Fibrosis
                                        Figure 2.

-------
agent to critical tissues on the highly active surface of an asbestos fiber.

     Also in Figure 1, the leaching of magnesium ions from the asbestos surface
is thought to interfer with solubility and ionic distribution of calcium.  One
manifestation of a disturbance in calcium metabolism is the formation of pleural
plaques.  Another manifestation is the induction of an orthodox to aggregate
transition (0 to A Transition) of mitochondria causing destruction of normal
mesothelial cells.  Surviving abnormal mesothelial cells could grow in an un-
controlled environment according to the bioenergetics and tumor growth theory
described by Racker.3

     Thus, a successful chemical treatment to detoxify asbestos depends on
three principles.

1.  Silicate binding sites must be masked by an agent that remains in place
    under physiological conditions.

2.  Leachable ions such as magnesium must be removed.

3.  The desirable physical attributes of asbestos such as strength, bulk
    density, surface area, magnetic properties, flow characteristics, heat,
    and chemical resistance must be essentially unchanged.

     As an initial approach and assuming that the formation of a ferruginous
body is an attempt to detoxify the absorbed asbestos, a proprietary process has
been developed which prepares a highly saturated synthetic ferruginous body.  The
process involving iron uses readily^ available, relatively inexpensive raw mater-
ials, and chemical compositions of treated asbestos have been prepared using
chrysotile, amosite, crocidolite, and anthophyllite.  The treatment process
has also been extended to produce chemical compositions of asbestos containing
cobalt, manganese, chromium, aluminum, and copper.

     Treated samples of amosite and chrysotile were  tested for cytotoxicity
using human lung macrophage cells in tissue cultures according to the procedure
recommended by Wade, et al.1*

    Figure 3 is  an example of  the  results using a UICC  chrysotile  B.   In the test,
cell cultures are allowed to grow for a 24-hr pre-exposure period.  The  cultures
are exposed to the material under test for 48 hours.  The media and most of  the
asbestos are removed, and the cells are cultured using  fresh media for an addi-
tional 24 hours.  Viable cells are counted at 24-hr  intervals during the test,
and five fields are counted for each culture.  The upper  curve shows the average
number of viable cells in the controls, the next curve  shows the average number
of viable cells in cultures exposed to a treated UICC chrysotile B,  and  the  bot-
tom curve shows the average number of viable cells  in cultures exposed to un-
treated UICC chrysotile B.  The amount of asbestos  in this series  of tests was
100 micrograms/ml.  Similar, but less dramatic results  were obtained in  tests
using a treated amosite.  From these results, the chemical treatment of  asbestos
decreases the cytotoxicity of the asbestos fiber to  human lung macrophage  cells.
                                      493

-------
   1000
Q_
o
CO
o
     500
CO
                                C-4 CONTROL

                                TREATED MATERIAL
                                                                   UNTREATED
        •24
24
48
72
                 INTRODUCTION
                  OF MATERIAL
             (START OF EXPOSURE)
  TIME
                  Figure 3.  Biology:  Initial data on cell viability — UICC chyrosotile B.

-------
     Table I Is a summary of physical attributes and differences caused by the
treatment process.  The magnetic rating decreases.  This could be an improvement
in the asbestos for certain electrical applications, but in other tests involving
phenolic molding compositions,  there is an increase in the preheating time.
The magnesium oxide content decreases,  and this is a desirable effect of the
treatment.  Color is dramatically changed.  The disadvantage is that the
color change may be unacceptable in certain products.   An advantage is that
the treated materials are readily identified.   In cement formulations and
phenolic resins, the color change is not a problem.   The viscosity of a spin-
ning solution containing AAA grade chrysotile  decreases as a result of the
treatment.  A large scale test  on a production line is needed to evaluate the
impact of decreased viscosity on the quality of the textile produced.  There
is a decrease in cement strength at a high level of treatment, but no changes
in cement strength were found at intermediate  or low levels of treatment.

     No changes in resin absorption, alkali resistance, acid resistance, and ther-
mal insulation properties were  produced as a result of treatment.  The fiber mill-
ing and processing is changed to a wet process.  Cytotoxicity shows a substantial
decrease.  The drainage rates of cement formulations decrease with increasing
levels of treatment.  A decrease in drainage rate may require changes in the
drying, curing, and forming of  asbestos cement products.  In working with sev-
eral grades of asbestos from AAA to 7RF99, a wet process tends to increase the
surface area and to decrease the bulk density  of longer fiber materials, but
these changes may be attenuated by controlling contact time in the wet process
and by more efficient dewatering.  The treated asbestos materials compare favor-
ably with the desirable attributes of raw or untreated asbestos.

     In summary, initial biological data show that chemical treatment of asbestos
to form a saturated synthetic ferruginous body decreases the cytotoxicity of asbes-
tos to human lung macrophage cells.  Physical  test data indicate that desirable
attributes of the fibers are retained.   If additional in vitro and in vivo bio-
logical tests are successful in demonstrating  a decrease in toxicity as a re-
sult of the chemical treatment  and the performance of treated material is ac-
ceptable in products, this would allow treated fibers to serve as substitutes
for asbestos in appropriate applications.

REFERENCES

1.  Flowers, E.S.:  Relationship Between Exposure to Asbestos, Collagen Forma-
    tion, Ferruginous Bodies, and Carcinoma, Amer. Ind. Hyg. Assoe. J., 729-
    742, 1974.

2.  Heppleston, A.G.:  Fibrogenic Action of Silica, Brit. Med. Bull. 25, 282-
    287, 1969.

3.  Racker, E.:  Bioenergetics  and the Problem of Tumor Growth, Amer. Sci.  60
    (1), 56-63, 1972.

4.  Wade, M.J., Lipkin, L.E., and Frank, A.L.:  Studies of  in vitro  Asbestos-
    Cell Interaction, J. Envir, Path, and Tox., 2,  1029-1039,  1979.
                                     495

-------
                                   TABLE 1.  DIFFERENCES CAUSED BY TREATMENT
JS
VO
Magnetic rating

Magnesium oxide content

Color

Viscosity of spinning solution

Resin absorption

Cement strength

Alkali resistance

Acid resistance

Thermal insulation

Fiber processing

Drainage rate of cement formulation

Biological effect (cytotoxicity)
Decrease

Decrease

Yellow, brown, blue, green

Decrease

No change

No change except at high level of treatment

No change

No change

No change

Wet process

Decreases with increasing level of treatment

Substantial decrease

-------
         DISCUSSION ON CHEMICAL DETOXIFICATION OF ASBESTOS FIBERS

QUESTION  (Mr.  Taitenann):   I am from Raybestos-Manhattan.  I would like to
          raise the question about  the  use  of the wet process.   Could  you
          describe the wet  process  to us, please?

ANSWER    (Dr.  Flowers):  This may  sound like blasphemy or a sacrilegious
          treatment of the  asbestos fiber,  but essentially, I make a slurry
          containing about  5 percent by weight of asbestos fiber,  which
          would be about  95 percent by  weight of water.   There  are two steps
          in addition to  the treatment  chemicals.   The material is filtered
          initially and then put  in a press.  I have been using my wine press
          to dewater the  asbestos.   Then it can either be shipped  as a wet
          cake containing about 30  percent  moisture, or it can  be  dried and
          then fiberized.

          I neglected to  mention  that in the laboratory scale operation,
          there are real  problems with  the  wet process in terms of maintain-
          ing the desirable surface or  bulk density of the material.   I
          found, however, that  in producing, say, a few grams of material
          I can control the contact time and the wet process.   I can also
          filter the material  fairly quickly and attenuate the  possible ad-
          verse effects on  enhancing or opening up  the surface, which  would
          make it unuseable in certain  processes.

          I can produce asbestos  that is fairly equivalent in surface  area
          by nitrogen permeability  and  such, but when I try to  go  to several
          pounds, tens of pounds, or hundreds of pounds,  I have found  that
          I just cannot scale  up  my laboratory to a reaction tank  for  this
          system.

          So the wet process may  be a problem and requires a  lot more  work.

QUESTION  (Mr.  Taitenann):   One other question.  You referred to viscosity
          in the spinning operation. What  type of  operation  are you
          referring to there?

ANSWER    (Dr.  Flowers):  Well, I am not very knowledgeable about  textiles in
          the production of fibers, but Dr. Kunsey  of  the Ontario Research
          Foundation did the evaluation of  the  spinning property,  and he
          said the viscosity changes,  and to really know what this means
          you have to produce enough sample to  put  it in a production line
          and see what effect it  has on that particular characteristic.

REMARK    (Mr.  Wright):  I  am from the  Steel Workers  Union.

          Let me just make one historical comment.   Let me first  say  that
          I think your research is very interesting,  but I want to, perhaps,
          inject a note of caution about how readily it ought  to  be accepted.

          First, I think that even if everything you say pans  out, there  are
          questions about the stability of the coatings  in the environment*

                                     497

-------
           and there are also, I think, some questions about the toxicity of
           various coating materials, especially things like manganese and
           possibly aluminum and chromium.

           But let me make the historical comment,  which is that back in the
           thirties, there was a lot of excitement  about the idea that
           aluminum oxide therapy would be effective in protecting miners
           from silicosis.  The idea was that if one went into the mines and
           then came out at the end of the day and  breathed aluminum oxide
           fumes or dust for some period of time, the aluminum oxide would
           naturally coat silica particles in the lungs and thereby protect
           the miner.  The therapy was based on two things:  the first was
           some preliminary biochemical theories about the way silica dust
           acted in the lungs, the idea that one could encapsulate whatever
           the problem was by the aluminum oxide; the second was based on
           some very preliminary animal studies. Those studies were dis-
           credited within, I think, about 10 years, but nevertheless, based
           on the very preliminary work, the underground mining industry and
           a lot of foundries adopted this procedure.  Many underground miners
           and foundry workers spent the last half  hour or 15 minutes of their
           work day, depending on how it was done,  breathing aluminum dust.

           Some of those people may have long-term  lung disease from that
           therapy, which was proven not to protect them against silicosis.
           That has been very well documented.  As  a result, the method was
           scientifically discredited by the late 1950s.   In 1978 we dis-
           covered several mines in Northern Canada that were still using the
           therapy and we stopped it very quickly.   And there may be more
           people out there who are still using it.

           The point I am trying to make is that it is very easy to jump to
           conclusions about the effectiveness of a particular detoxification
           process, and there may be some who would do that as an alternative
           to  cleaning up the work place.   I am not saying this to discourage
           your research.   I am saying it to discourage the too-rapid adoption
           of  a method that is not yet proven.  And I think if I were ques-
           tioned by one of the workers who I represent,  I certainly would not,
           at  this point,  say that treated asbestos should be considered any
           safer than untreated asbestos.   Maybe with more research,  but I
           think that will take a lot of additional work.

REMARK     (Dr.  Flowers):   I  agree with just  about  everything you said,  although
           I cannot confirm your experience regarding aluminum oxide as
           therapy in prevention of  silicosis.   But I tried to be fairly
           careful in how I characterized  the results of  our initial biolog-
           ical  tests.   In my summary,  I indicated  that  it is successful in
           some  rather  extensive additional biological in vitro and in vivo
          tests.
                                     498

-------
          Also,  if through process engineering and economics, we  find  that
          the material retains  the desirable physical properties  and will
          work in various industrial processes, then it could be  accepted
          as a process for chemical treatment and detoxification  of asbestos.
          From an economic and  biological point of view I think that iron
          oxide, or various forms of it, is the only real treatment that
          will be acceptable.

          There was somewhat of a chemical academic Interest to extend the
          treatment to chromium or other transition metals to show that this
          is a general reaction across  the transition metal group and  also
          with amphoteric materials.

          I agree that a lot more work  needs to be done.  In our  communica-
          tions with the EPA,  they say  that the tests, particularly the
          biological data, will have to be very persuasive for them to
          accept such a substitute.  And that is not only for our material,
          but also for all the 60 or so materials that have been  proposed
          as substitutes here  over the  last few days.

REMARK    (Mr. Wright):  I would like to make one final comment,  not about  what
          you presented, which I have no quarrel with, but about  iron  oxide.
          There are some questions about iron oxide itself being  a cocarcinogen
          based on two things.   One is  some work that Saffiotti and others  did,
          exposing, I think, Syrian golden hamsters simultaneously to  iron  oxide,
          and a carcinogen. This showed a. greater response when  the iron oxide
          was administered along with the carcinogen than when the carcinogen
          was administered alone, even  though iron oxide alone did not give any
          increased carcinogenic response.

          Also there have been some epidemiologic studies in gray iron and
          steel foundries indicating an increased risk of cancer  in  those
          work places.  We do  not know  what that is caused by, but one hypo-
          thesis is iron oxide, so you  have to be careful.

REMARK    (Dr. Flowers):  Iron oxides are a normal waste product  of  oxidated
          metabolism in cells.  The  ferric hydroxide  is  sometimes viewed as
          the brown gelatinous amorphous material  floating  around in the
          cells, so essentially, the  iron  is  something  like  that  amorphous
          gelatinous material.  However,  from our X-ray defraction data, we
          have prepared a highly ordered form of  this material,  using the
          asbestos surface as template  for  its precipitation and formation.

QUESTION  (Dr. Fatel):  I am from the New Jersey  State Department of Health.
          I have three questions.   One  is what happens  in your lung cell
          tests beyond 72 hours after treatment.   The other is what happens
          to the acoustic properties of asbestos.   Finally,  is this process
          useful only in the manufacturing aspect of asbestos or could it  be
          used after the product has already been manufactured,  for example,
          in school ceilings?  Can you treat the manufactured product  so
          that it will penetrate further and not only remain on  the surface?
                                     499

-------
 ANSWER    (Dr. Flowers):  We do not know what happens after 72 hours because
           the test protocol stops after 72 hours.  This is a short-term
           assay to evaluate the initial biological response.

           We do not look at acoustic properties.  Ontario Research can make
           test panels and measure the acoustic properties, but that was one
           test we did not look at.

           The process is essentially a technique for contacting the asbestos
           surface with a solution of treatment chemicals.  Depending on your
           degree of imagination, you could contact the exposed asbestos at
           the mine with the treatment chemical.  I claim that you could
           develop devices for contacting asbestos wherever you find it, in-
           cluding those asbestos fibers which are already present in the
           lungs of people who have been exposed, thereby providing a syn-
           thetic process for deriving a synthetic ferruginous body from an
           exogenous source of ferric salts.

 REMARK    (Dr. Cooper):   1 am from Berkeley.   I wanted to make a comment on the
           remarks of the Steel Workers' representative.  1 certainly agree
           with him and with Dr. Flowers that something like this has to be
           studied and approached very cautiously and certainly is not a sub-
           stitute for industrial hygiene.

           I do not think that the analogy with aluminum and silicosis is
           quite applicable here.  There is very good biologic evidence that
           aluminum and iron do modify the fibrogenic potential of silica;
           that has not been, shall we say, discredited.  The thing that has
           been discredited is the inappropriate application of aluminum and
           iron to the prevention of silicosis.  Substituting the addition of
           inhaled aluminum powder for adequate dust control has been justi-
           fiably discredited.   Since it was clearly impossible to coat with
           aluminum the quartz particles that resulted from drilling a hole
           in a hard-rock mine, the effort was made to coat them after they
           got into the body.  Although I think it is a difficult path that
           has to be followed to establish these things, I do not think that
           that analogy should be used to discredit this type of approach.

QUESTION   (Mr.  Wilkin):   I am with Dresser Industry.   The three criteria that
           you provide for detoxifying the fibers are:   removing the mag-
           nesium oxide surface,  ensuring the surface is stable to alkaline
           conditions,  and maintaining the same strength and flow properties
           of  the resultant material.   Do you have any comments on the other
           methods of  doing this,  such as the  acid leaching and organosilane
           or  sodium silicate treatments that are currently patented?

ANSWER     (Dr. Flowers):  I was very interested  in the Dow patents, for example,
           involving the molybdate and  tungstate treatment.   They used a
           Grade  7  chrysotile and  showed that  hemolytic activity could be de-
           creased  up to 100  percent by treating the surface with the molybdate
   *       and the tungstates.  They used a wet process.   I think they
                                      500

-------
          also removed some  of  the brucite or the magnesium oxide associated
          with the surface.   The metallic tungstate and molybdate salts are
          alkaline resistant, so I think it does not violate  the three prin-
          ciples that I have enunciated.

          The heat treatment of asbestos actually drives off  hydroxide by
          hydroxide reaction or oxidation with oxygen.  This  gets rid of
          hydroxyl groups.   I think  that when you hydrate or  rehydrate sili-
          cate bonds you may have some  problems once they are deposited in a
          physiological system.

          One other treatment used is the removal of magnesium oxides and
          other metals by moderately strong acid treatment of the surface.
          According to the paper presented in May, by Marcelle Cahette, at the
          Fourth International  Conference on Asbestos in Italy, they have  suc-
          cessfully demonstrated decreased cytotoxicity and decreased release
          of enzymes from membranes  and also decreased hemolytic action of the
          chrysotile asbestos,  which had been subjected to the moderate acid
          treatment.

          So, yes, there are other approaches.  My approach was to  mimic what
          I consider to be a detoxification attempt by the body and to make
          a synthetic ferruginous body.

QUESTION  (Mr. Wilkin):  Would  your  studies also include the  possibilities of
          detoxification by  the reaction of the surface with  an organosilane
          to make the surface hydrophobia?

ANSWER    (Dr. Flowers):  I  cannot comment on that one way or the other, but I
          really have not given any  thought to that particular process.

REMARK    (Mr. Wilkin):  There  are a. few applications for asbestos  that would
          probably best be  served by a  hydrophobic  coating  rather  than a
          hydrophilic coating.

REMARK    (Dr. Flowers):  I do  not  want to make my process  mutually exclusive
          of other processes.  I think there  is probably room in the sub-
          stitute field for many products.

REMARK    (Dr. Gross):  I am with  the Industrial  Health Foundation.  If phago-
          cytosis to these treated fibers does take place,  then we are up
          against another facet that contradicts  the present theory of the
          pathogenicity of asbestos, namely,  the  theory that incomplete
          phagocytosis of the asbestos fiber causes leakage of intracellular
          enzymes into the surrounding medium and, consequently, into the
          surrounding tissues.   The leakage of these intracellular enzymes
          would then cause tissue damage and, ultimately cancer.

          If your demonstrated lack of cytotoxicity by the treated asbestos
          fiber takes place in spite of phagocytosis, then this theory falls
          into the  ash can,  and we do not have a viable theory for the patho-
          genicity  of asbestos.  Our concern for the substitutes for asbestos,

                                     501

-------
           like man-made vitreous fibers, also should be abated because this
           concern is based on the theory that the geometry of the fiber in
           great part is responsible for the pathogenicity of fibers.

           It is agreed that the geometry of a fiber is responsible for the
           fiber landing at the target site, but if this theory about  leakage of
           intracellular enzymes into incomplete phagocytosis is destroyed, then
           we should not have any concern for the pathoeenicity of manmade fibers.

 QUESTION  (Dr.  Bernstein):^  I think Dr.  Gross's comments are well taken.   I
           would like to ask you, along the same lines, did you do size mea-
           surements of your fibers, and if you did, did you do it before they
           were treated and after they were treated, and what sizes were they?

 ANSWER    (Dr.  Flowers):   Yes,  we have rather extensive data,  both the  light
           microscope and the electronmicroscope data on the size distribution
           of the fibers and the effect of treatment on size.

           There is a slight increase in average diameter after treatment,
           compared to before treatment.

 QUESTION  (Dr. "Bernstein):  What were the figures?

 ANSWER    (Dr.  Flowers):   I  do  not have  the figures with me.

 QUESTION  (Dr.  Bernstein):  What about the length?  Did you look at length?

 ANSWER    (Dr.  Flowers):   No.  I used Grades Triple A chrysotile, Grades 4 and  5
           chrysotile, Grade 7 type purity, Grade 7 RF 99,  and these go from
           extremely long materials to extremely short fine fibers.

 REMARK    (Dr.  Bernstein):  Well, I think it is important  to point out that  the
           effects you have shown could be explained by either a change in
           diameter,  an increase in diameter, perhaps, or a decrease in
           diameter and/or length.  And until that is straightened out and
           put on the record, it is really unfair to interpret the results.

QUESTION   (Dr. Flowers):   What  percentage  change  would be  significant,  in
           your  opinion?

ANSWER     (Dr.  Bernstein):   I could not venture a guess until  I saw your  results
           and I  do not know  if  I could venture a guess after that until I
           have  seen  the experiment.

REMARK     (Dr. Flowers):   There is less  than about  a  5 percent change in diam-
           eter and no change in length.

          We mainly  took  pictures sufficient to  count the  cells,  but  not to
          evaluate whether phagocytosis  was going on.   So  that is an  omission.
                                     502

-------
REMARK
REMARK
In the protocol that we followed, we primarily were interested in
seeing if we could demonstrate a decrease in cytotoxicity and that
was the one issue we looked at.  We did not look at some of these
other issues, which now seem to be more important, or assuming more
importance.

(Dr. Bernstein):  Relating to Dr. Gross's comments, I think if you can
demonstrate that the phagocytes are ignoring your coated fiber
(and you probably could do that using the methods that we saw from
the Brookhaven National Laboratory), you might'be able to support
your findings a lot better.

(Dr.  Flowers):   We do not make any claims that this is the only test
that we are going to run.  As a matter of fact, this afternoon
I am going to talk about criteria for acceptable test protocol for
evaluating proposed substitutes.  This was based on an unofficial
request to EPA under Section 4(g) of TSCA, as a petition for accept-
able test protocols for evaluating and, subsequently, if successful,
registering a product for use.  We do plan more extensive in vitro
and in vivo tests.
                                    503

-------
                 HEALTH CONSIDERATIONS IN THE  PERLITE INDUSTRY

                                       by

                              W.  Clark Cooper,  M.D.
                        2150 Shattuck Avenue,  Suite 401
                              Berkeley, California




                                     ABSTRACT

   Commercial perlite  is a naturally occurring glass of volcanic  origin which,
   when heated, expands to form a product of low density,  high surface area, and
   low thermal conductivity.  Expanded perlite is used in thermal insulation as
   a filter aid, as  an inert carrier and filler, and as a soil conditioner.  Per-
   lite is a noncrystalline silicate.  Most ores and products contain less than
   1 percent quartz  or cristobalite, although there are commercial deposits with
   as much as 5 percent quartz.

   Studies in animals  reported in 1953 showed no evidence of pulmonary fibrosis.
   Nevertheless, most  major producers and processors provide periodic chest films.
   A review of films in 240 perlite workers which was reported in 1975 showed no
   evidence of pneumoconiosis associated with perlite exposures:  however, only 28
   of those studied  had been in the industry for  15 years and only 7 for 20 years.
   A recent updated  review, which involved 43 men with 15 or more years in the in-
   dustry and 18 with  20 or more years, again showed no evidence of perlite-related
   pneumoconiosis.   Pulmonary function in. 117 perlite workers was studied in  1975;
   there was no decrement in forced vital capacity.  There was slight, but not sta-
   tistically significant, reduction in average forced expiratory volume.  An up-
   dated review of pulmonary function is now underway; preliminary findings do not
   indicate a significant effect from perlite.  Current recommendations are that
   perlite be regarded as a nuisance dust except  in products with 1 percent or more
   crystalline silica.
INTRODUCTION

     Perlite is a naturally occuring  noncrystalline silicate of  volcanic origin
which  expands when heated to form a product of low density, high surface area,
and low thermal conductivity.  It is  not fibrous.   The principal end uses  of ex-
panded perlite are filter aids, construction aggregates, horticultural aggre-
gates, acoustical tile and insulation products.   It can be regarded as an  asbes-
tos substitute in only a limited sense, as in some specialized insulation  mater-
ials.   The principle  competitive commodities are vermiculite,  pumice, slag,
diatomite and expanded clay and shale.

                                         505

-------
      The perlite industry has a comparatively short history,  the  commercial
 possibilities of the material not having been recognized until after World War
 II.  Production in the United States'began in 1946; there are now 13 mines in
 6 western states, with New Mexico accounting for 88 percent of the total out-
 put in 1979.  In that year processed perlite sold or used in the  United States
 totalled 650,000 tons.

      Mining of perlite is by open pit.   Although expansion is carried  out by
 some producers near the mining sites, it is a common practice to  ship  the crude
 ores to expanding facilities near points of distribution.

      Expansion is carried out by injecting finely divided crude ore into fur-
 naces fired by gas or oil, where temperatures are maintained in the range of
 1400 to 2000°F (760-1100°C).  The 2 to 5 percent combined water in the crude
 ore causes the particles to "pop" or expand, producing a product  with  a bulk
 weight of 3 to 12 pounds per cubic foot, compared to a bulk weight of  65 to
 75 pounds per cubic foot for crushed and sized crude perlite ore.   After ex-
 panding, the particles are classified by size prior to shipment or use.

 DESCRIPTION OF PRODUCT

      Perlite ores and expanded perlite are largely aluminum silicate,  in a
 noncrystalline, nonfibrous form.   Some perlite ores contain small amounts of
 crystalline silica; i.e., quartz, but most do not.  For example,  analyses of
 se/eral samples by the Bureau of Mines in 1956 showed quartz  concentrations
 ranging from less than 1 percent to 3.0 percent.   Other analyses  in 1971 by
 McCrone Associates showed quartz concentrations ranging from under 0.5 per-
 cent to 5.8 percent in ores, and from 0.5 percent to 5.2 percent  in expanded
 perlite.   In 1979, five ores and resulting products were analyzed for  the
 Perlite Institute.  Quartz and cristobalite concentrations were measured in
 the ores and products, and in total airborne dust and respirable  dust.  In
 most,  quartz was below detectable range; the highest concentration in  respirable
 dust,  from one product, was 1.7 percent.  In no case did cristobalite  exceed
 1  percent.

     The potential for dust exposures in the perlite industry are those of
 any operation in which there is open pit mining,  crushing, screening,  and
 loading of  ores,  and the subsequent production and handling of a  finely par-
 ticulate product.   Those who use expanded perlite in the manufacture of various
 end products are  of course also subject to potential dust exposures.

     There  are no published figures on airborne concentrations of dust in the
 perlite industry,  but available unpublished data indicate that nuisance dust
 levels  are  easily exceeded during some  operations, such as bagging or  cleanup,
 unless  precautions are taken.

 BIOLOGIC  EFFECTS

     In 1953 Vorwald1  et al reported no evidence  of fibrosis  following intra-
 tracheal  injection  of  0.5 percent of a  5 percent  suspension weekly in  guinea
pigs for  3 weeks.   Nine products  were tested.   One product was tested  by inha-
lation in guinea pigs  and rats  over a period of 18 months with an average

                                      506

-------
dosage of 590 mppcf (6.4 mg/ft3 or 226 mg/m3).   No  significant pulmonary reac-
tion was observed.  Schepers2 subsequently reported that the inhalation of high
concentrations of perlite appeared to stimulate the progression of experimental
tuberculosis in guinea pigs.   Infections,  however,  became arrested several
months after exposures stopped.  The exposures  were extremely high, being main-
tained for 8 hours a day, 5-1/2 days a week for 6 months at average concentra-
tions of 582 mppcf with 50 percent to 80 percent in a respirable size range.
On a weight basis, exposures averaged 8.03 mg/ft3 or 284 mg/m3.

STUDIES IN EXPOSED POPULATIONS

     Advisors to the perlite industry in 1953 recommended that perlite producers
and expanders maintain medical surveillance of  exposed workers and not permit
unrestricted dust exposures.   These programs have made available files of chest
radiographs which in recent years have become useful to determine if there has
been any evidence of pneumoconiosis.

     The first published review,3 supported by  a contract from the Perlite
Institute, Inc., involved films taken through 1974  (Table 1).  Records were
obtained on 100 men identified as working  in perlite mining operations and
185 in expanding operations.   The latter offered opportunities for exposure
either to crude or expanded perlite.  Films were obtained on 240 individuals.
One individual found to have simple pneumoconiosis  and one with complicated
pneumoconiosis had formerly been employed  in the diatomaceous earth industry,
one for 13 years, the other for 24 years.   Because  only 28 of those studied
had been employed for 15 or more years in  perlite,  and only 7 for 20 or more
years, the results were regarded as preliminary.  It was concluded that con-
tinued surveillance was 'essential to make  sure  that there are no effects with
more prolonged exposures.  Studies of pulmonary function of individuals with
relatively long exposures were recommended.

     An updated radiographic review was carried out in 19791* (Table 2), in
which 6 of the 10 plants which participated in the 1974 study took part.
These six plants had furnished over 90 percent of those included in the first
study.  The study was limited to men with 5 or more years in the industry.
There were 130 individuals whose films were reviewed; 93 of these had been
included in the 1974 study.  Of the participants, 46 were from plants which
mined and shipped crude perlite; 62 were from an operation where perlite was
mined and also expanded, while the remaining 22 were from plants where crude
perlite was expanded.  Table 2 summarizes the film interpretations, based on
readings by radiologists certified as 8 readers.  Table 3 provides details on
the four individuals interpreted as positive for pneumoconiosis.  There still
appears no pattern of disease associated with working with perlite.

PULMONARY FUNCTION

     In June 1975 pulmonary ventilatory function was studied  in  117 men em-
ployed in three plants engaged in the mining or processing of perlite.5   Forced
vital capacity and forced expiratory volumes in one-second were  determined
using a 9-liter Collins spirometer  and a model  II Jones  Pulmonor.  A detailed
summary of the findings was reported in November 1976.   Forced vital capacity
measurements did not show reductions that correlated with length of  exposure.

                                      507

-------
       TABLE 1.  FILM INTERPRETATIONS IN PERLITE WORKERS
                 (1974 Survey)
Years in the
Per lite Industry
0- 4
5- 9
10-14
15-19
20-24
Total
No. of men
with films
106
52
54
21
7
240
Changes consistent with
Negative
105
50
52b
18
6
231
Doubtful
1
1
1
3d
le

pneumoconiosis
Positive
0
la
lc
0
0
2
a                          •       '
 Complicated diatomite pneumoconiosis (24 years in DE).
 One with residual of pneumonitis.
CSimple diatomite pneumoconiosis, exposure approximately 13 years.
 One with exposure to diatomaceous earth.
6One with exposure to diatomaceous earth.
                             508

-------
         TABLE 2.  FILM INTERPRETATIONS RELATED TO YEARS IN THE
                   PERLITE INDUSTRY (1979 Survey)
Changes consistent with pneumoconiosis
Years
5- 9
10-14
15-19
20-24
25-29
Total
No.
54
33
25
13
5
130
Negative
(0/-0/0)
49
28
21
11
4
113
Doubtful
0/1 1/0
1 2
2 3
1 1
2 -
_ •>
6 7
Positive
1/1 2/2 3/3
1
-
2
-
-
3
- la
- -
- -
-
- -
- 1
          HPresent in pre-employment film 1966, interpreted as
           pleural changes at that time.
        TABLE 3.  FILMS INTERPRETED AS POSITIVE (1/1 or greater)

No.  Classification  Age  Years       Jobs           Comments

 1        1/1         48    5    truck driver    no previous film

 2        1/1         54   17    bulldozer op.   no change since
                                 truck driver    1967

 3        1/1         48   18    mobile eq. op.  slight change
                                 maint. mech.    since 1960

 4        3/3C        61    9    general worker  called pleural
                                 (6 years)       changes in 1966
                                 grizzly op.     and 1974.  Term:
                                 maint. mech.    1975; died 1976
                                                 (no autopsy)
                                   509

-------
 There were slight reductions in FEV].  and  in the FEVi/FVC ratio.  Although
 these could not be entirely explained by  cigarette  smoking and were associated
 with number of years in the perlite industry,  the reductions were not statis-
 tically significant beyond the 0.1 percent level.

      The major producers of perlite continue to maintain a program of periodic
 chest films and since 1975 have provided  annual testing of pulmonary ventilatory
 function.  An analysis of later pulmonary function  results obtained during 1977,
 1978, and 1979 is now underway;  preliminary indications'are that there is no
 evidence of a systematic reduction of function associated with perlite exposure.

 SUMMARY AND CONCLUSIONS

      There is no evidence to indicate that individuals  engaged in the mining,
 expansion, or use of perlite develop  pneumoconiosis.  Nevertheless, it is
 recommended that there be strict adherence to  nuisance  dust levels, assurance
 that quartz levels are never excessive, periodic medical surveillance, and
 retention of records and chest films  for  periodic reevaluation.

 REFERENCES

 1.    Vorwald, A.  J.   Perlite Dust Investigation, Final  Report:  The effect
      of inhaled perlite dust upon the lungs of normal animals, to the Perlite
      Institute by the Saranac Laboratory  of the Trudeau Foundation, Saranac
      Lake,  New York.   March 12,  1953  (Perlite  Institute, New York, 1953).

 2.    Schepers,  G.  W.  H.   The biotoxicity  of perlite:  Report to the Perlite
      Institute by the Saranac Laboratory,  March 19, 1955 (Perlite Institute,
      New York).

 3.    Cooper,  W.  C.   Radiographic Survey of Perlite Workers.  Journal of
      Occupational Medicine 17:304-307, 1975.

 4.    Cooper,  W.  C.   Review of Chest Radiograms of Perlite Workers, pre-
      liminary report presented at 31st Annual  Meeting of Perlite Institute,
      Inc., April 22,  1980.

5.   Cooper,  W.  C.   Pulmonary Function in  Perlite Workers.  Journal of
     Occupational  Medicine,  18:723-729, 1976.
                                      510

-------
                             DISCUSSION ON PERLITE

QUESTION  (Dr. Langer):   I am from Mt.  Sinai.

          Is the silica present in this material as discrete particulates or
          does it have crystalline domains and are the surfaces a little bit
          greater?  In other words, if there is a 1 to 10 silica content, does
          it mean 1 percent is discrete particles.  Do you have more exposed
          silica surface?

ANSWER    (Dr. Cooper):   I do not know and I am not sure that that is known.
          I think that it is more or less a contaminant associated with the
          ore body, but I do not know.
                                      511

-------
                     REVIEW OF THE HEALTH EFFECTS OF MICAS

                                     by

                               Mr. Ilmar Lusis
                         Manager Industrial Hygiene
                         Martin Marietta Corporation
                            6801 Rockledge Drive
                          Bethesda, Maryland 20034


                                   ABSTRACT

    Available literature on locations, characteristics and  uses of micas is briefly
    discussed.

    Available world literature on bioactivity and pneumoconiosis attributed to
    micas is reviewed.  An attempt is made to separate cause-effect relationships
    according to the type of mica causing the exposure or used in the experiment.
    Insufficient data were found to make the distinction.   Electron microscope
    photographs of micas from various sources are enclosed.
     According to Petkof  in his  chapter on mica in the compendium "Industrial
Minerals and Rocks" mica  or micas  are  predominately potassium, aluminum silicates
with varying amounts of magnesium,  iron, lithium and some other trace metals.1
These minerals have layered lattice-type internal structure, with tetrahedral
grouping of oxygen atoms  surrounding silicon atoms or aluminum atoms.  Tetra-
hedral groupings result in pseudohexagonal network within a plane.  The double
or mirror image network is superimposed on the "peak" side of the tetrahedron
and the two layers are joined  by hydroxyl groups or metallic ions such as
aluminum, magnesium, or lithium.   These double layered structures are joined
by potassium atoms.  The  potassium atom locations constitute the cleavage
plane of mica.  The American Conference of Government Industrial Hygienists
defines micas as "nonfibrous silicate  occurring in plate form" including nine
different species.2

     Distribution of micas is  probably worldwide.  It is found both  in metamorphic
and igneous rock.  The decomposition of such rock produces sand and  clay  and
introduces finely ground  mica  into our environment where it is naturally  distri-
buted by wind and water the same way as any other mineral.  In relation  to man
this condition must have  existed throughout the history of mankind.

     However, let us get  back  to science.  When we consider the idealized chemi-
cal structures of the complete crystal, it becomes obvious  that muscovite and
phlogopite appear structurally more uniform than biotite.   (Fig.  T)   These  two

                                       513

-------
MARTIN MARIETTA CORPORATION
Idealized Mica Formulas
 MUSCOVITE   -  K2 AI4 [Si6AL2020] [OH,F)4
   COLORLESS

 PHLOGOPITE  -  K2 (Mg, Fe+2)6 [Si6 AI2 020] [OH.F]4
   COLORLESS
   TO BROWN

 BIOTITE       -  K2 (Mg. Fe+2)6.4  (Fe+3, Al, Ti)0.2 [Si6.5 At 2.31 OQ-2)
   BLACK.
   BROWN-             (OH. F)4 2
   GREEN                   4-Z
                             Figure 1.

-------
are the predominant commercially used micas.  Muscovite probably accounts for
about 90 percent of the mica used in the world.   This  became quite obvious
during the literature search.

     This approximate schematic does not lay  claim to  perfection; (Fig.  2) it
does depict approximate possible paths of  conversion from one mineral to another
over a long period of time.   Other paths may  be  entirely possible because there
is one concept in geology that is absolutely  true—for every rule and general-
ization there are numerous exceptions.

     I would like to call your attention to the  term "pegmatite."  It really
refers to the structure and not to the composition of  this particular granite
variety.  Returning to the economically important micas, namely muscovite and
phlogopite, it is important to note that almost  all of the muscovite recovered
in the United States is a co-product or by-product in  quartz, feldspar,  kaolin
and perhaps garnet recoveries, or vice versa. Consequently the impurities of
that nature could be expected in the commercial  grade  micas.  Sericite,  which
is a hydrothermal disintegration or weathering process end product or possibly
a direct result of metamorphosis, contains considerable amounts of free  silica.
Even though on occasion cited in the literature  as a mica, it should be  con-
sidered as part of the clay family, at least  for commodity purposes.  One
author claims that pure mica dust in the lung is less  fibrogenic than a  mixture
of mica and free silica.4

     The main commercial products of micas are sheet mica, scrap or flake mica
and ground mica.  Sheet mica, both muscovite  and phlogopite, is found visually
and hand-picked from the mined matrix rock.  The sheets are hand separated in
a way similar to separating pages from a wet  book; the same material can be
sold also in "block form."  The value of sheet mica depends on size, clarity,
color and in some occasions on the dielectric properties.  In ground micas,
depending on the end use, other properties may be important.

     The leading manufacturers of sheet mica  (splittings and block) in the
world are India, Brazil and Malagasy.  Sheet  mica is used primarily in the
manufacture of electrical appliances, vacuum tubes, electronics and capacitors.
From a physiological and perhaps health standpoint, the scrap, ground and flake
mica is more significant.   (Fig. 3)  The United States is still the leader in
scrap, ground and flake mica production.  Looking at the 1977 data reported by
U.S. Bureau of Mines, one can see the distribution of end-products according
to standard industrial classification codes.5

     The following map  (Fig. 4) shows the counties in  the United  States  in which
mica is produced for commercial purposes.   The  consuming  states  are again not
particularly widely distributed.  Over 80 percent of U.S. block mica and film
used in fabrication is consumed in New York,  Pennsylvania and Virginia.   North
Carolina, Massachusetts, and Ohio are the other consuming states.

     Ground mica in 1979 was produced in Alabama, New  Hampshire,  New Mexico,
North Carolina, Pennsylvania, South Carolina and  South Dako'ta.   The same states
also produced mica flakes.  Mica flake was also produced  in Connecticut  and
Georgia.  When export and import data are considered,  United States exports and
imports about 6 million pounds of mica each  year.  For comparative purposes,

                                       515

-------
                   MARTIN MARIETTA CORPORATION
Ol
                     PEGMATITE                      (IGNEOUS OR MET AMORPHOUS

                         I  (QUARTZ, FELDSPAR MICAS)        ^DEPOSITS)
                         I             •     i
                       ILLITE 4-*'
                             **GLAUCONITE \


                                          SERICITE
•CHLORITE



•CLAY

 VARIETIES

                                               Figure 2.

-------
MARTIN MARIETTA CORPORATION
Mica  (Scrap and  Flake)
  SUPPLY-DEMAND RELATIONSHIPS 1977
       THOUSAND SHORT TONS OF MICA
 WORLD PRODUCTION
	I	
DELAMINATED
           IMIHISMTIS
             in
             MOU
            aim
             nc
   WORLD TOTAL
      276E
                                                           KEY
                                                     ( enure)
                                                    X STMBMB MOUSniM OASSRUTOI
                                                     » SOW MM
                                                                              BUREAU OF MINES
                                                                    U.S. DEPARTMENT OF THE INTERIOR
                                           Figure 3.

-------
   MARTIN MARIETTA CORPORATION
  Mica Mining Counties (including Sericite) In U.S.A./Spring 1980
00
                                      Figure 4.

-------
the total world production of micas in 1978  was  533  million pounds.   In 1979
it dropped to 528 million pounds.6   These estimates  do not  include the pro-
duction of such countries as Rumania.   U.S.  consumption of  sheet and scrap
or ground mica at the same time was 5.1 million  pounds of sheet and 244 mil-
lion pounds of ground mica.  The production  of mica  paper should be noted as
possible means of substituting sheet mica.

     However, geology, geographic distribution and economic usefulness of
mica is not the title of this paper.  In the search  of the  health effects of
micas, as the title of the paper would indicate,  it  is difficult to establish
a starting point.  In 1933 in the Journal of Indusrial Hygiene, W. R.  Jones
reported finding sericite in silicotic lungs and proposed the sericite crys-
tals as the causative factor in pulmonary silicosis.   In May of 1934,  A. Poli-
card from the University of Lyon in France reports on his animal experimenta-
tion involving finely ground "white mica dust,"  to which he subjects test
animals in substantial doses for four  hours  a day, sacrificing them after three,
five, sixteen and thirty days of exposure.   He concludes that the lung changes
have occurred, namely that "the altered cells are grouped in plaques in the
alveoli.  About them the pulmonary histocites gather, the aggregate forming
a sort of mica granuloma."7  His experimental evaluation techniques were lim-
ited to an optical microscope.  The paper, unfortunately, does not state the
dust concentration to which the animals were subjected.

     The next significant publication  chronologically is the almost classic
study by Dreessen, Dallavale and others, entitled "Pneumoconiosis Among Mica
and Pegmatite Workers," also known as  U.S. Public Health Bulletin No. 250.8
This study has served as a basis for threshold  limit value  determination of
mica dust in the United States.  Some  of the airborne dust  concentrations
reported in the study were extremely high, such  as kiln drying and manual bag-
ging of mica, averaging 116 million particles per cubic foot and crusher dust
ranging from 40 to 1,000 million particles per  cubic foot.   These values would
apply to mica mining and recovery.  Wet mica grinding operations ranged between
3.1 million particles per cubic foot and 158 million particles per cubic foot
in the drying stage.

     Mica fabricating, such as mica sheet trimming,  splitting and punching
produced dust concentrations of only 3.2 million particles per cubic foot on
the average.  Consequently, no pneumoconiosis cases were seen in that group
of workers.  In mica grinders, symptoms of pneumoconiosis appeared between the
tenth and nineteenth year of employment.  The disease symptoms resemble those
of silicosis.  The symptoms were supported by x-ray diagnosis indicating gran-
ulomas and fibrosis of the pleura.  The following figure taken from the bul-
letin dramatically portrays the time-concentration relationship of dusty trades
with respect to the development of pneumoconiosis.   (Fig. 5)  This figure  rep-
resents the findings in 798 workers including the 57 mica workers exposed  to
mixed dust and classified according to length of  employment  as well as  the
average dust concentration.  The graph deals with all pneumoconiosis  cases.
After five years of employment, the number of workers  in each  grouping decreases
with the increase in years of  employment.  The percentage  represents  the chance
of finding pneumoconiosis.  The 66  percent  group consists  only of six individuals
of which four had pneumoconiosis.   Of  interest  is Appendix II in the study, pro-
duced by Dr. John W. Miller.   He used  some of the minerals encountered in the

                                      519

-------
                       MARTIN MARIETTA CORPORATION
ro
o
                               RELATION OF AVERAGE DuST CONCENTRATION AND DURATION OT
                               OUST EXPOSURE TO THE PCI«CCNTACC OF WORKERS FOUND TO HAVC PNKUMO-

                               CONIOSIS.
                        Dreessen, W.  C.» et al.3  p.50.
                                                         Figure 5.

-------
study to conduct an animal experiment  with  guinea pigs.   He  used finely ground
muscovite mica with a very small amount  of  quartz and  feldspar  present.   He
found that mica produced an "inert  reaction."   The term  "inert" he defines as
a condition when the dust remains practically  unchanged  in the  tissue and does
not institute a proliferation reaction like the more soluble quartz.   The micro-
scopic appearance of the muscovite  dust  used was  described as "plates and
fibers."

     The field work was conducted between 1937 and 1939.   The study was pub-
lished in 1940.  At that time it was standard  practice to report airborne
dust concentrations in million particles per cubic foot.   This  dust counting
method had quite a few drawbacks as the  assessment method for airborne dust con-
centration.  In the 1979 American Conference of Governmental Industrial Hygien-
ists adopted a method to convert million particles per cubic foot to  a mass
limit of milligrams per cubic meter.  A  good approximation is 6.37 million
particles per cubic foot as being equal  to  1 milligram per cubic meter.   The  .
converted threshold limit value for a 40 hour  workweek is, therefore, 3 mil-
ligrams per cubic meter for respirable size particles  and 6  milligrams per
cubic meter for total airborne dust.9  Respirable dust particles are  those
with aerodynamic diameter of less than five microns.   It is  interesting to
note that the British threshold limit value for mica is  one  milligram per
cubic meter for respirable size and ten  milligrams per cubic meter for total
airborne dust.

     The late 1940*s and early 1950's produced a  series  of large scale employee
surveys in American occupational medical literature.   Vestal and others in
1943, reported a high incidence of  tuberculosis upon clinical and x-ray exam-
inations of 1,021 men applying for  work  in  the mica industries  in North Carolina.
Even though there was no associated field investigation, Vestal's conclusions
indicate that dust and tuberculosis pathology  among the  workers previously
exposed to "pure mica" is more pronounced than among those exposed to other
minerals.10  This conclusion was later questioned because quartz was  present
in all of the other minerals.11

     Dr. Adelaide Ross Smith, working with data gathered by the New York State
Department of Labor, published a paper in 1952 on calcifications of the pleura
resulting from exposure to certain dusts.12  The paper which is based largely
on chest x-ray survey data conducted by the Division of  Industrial Hygiene of
New York State Department of Labor, reports the following:

    "A group of 302 men exposed to  mica dust were employed by a concern  engaged
in making mica insulators of various types.  Mica is a complex  silicate  of po-
tassium, aluminum, magnesium, calcium and fluorine.  A number of  operations  in
the plant were dusty, including the sawing, sanding and drumming  of  insulators.
None of the mica workers in this study showed pneumoconiosis though  Dreessen
and others have found that mica dust is capable of causing  this condition if
present in sufficient intensity."  Unfortunately, this  study does not mention
any concentrations to which these workers were exposed.    The length  of  employ-
ment is mentioned in two clinical cases described.  The report  does  state that
lung calcifications were found in five of the 302 workers reviewed.   As these
were x-ray findings they do not deal with the origin  of calcifications.
                                      521

-------
      Jones' hypothesis of 1933 found an echo in 1947.  King and others asso-
 ciated with the British Postgraduate Medical School in London, investigated
 South Wales sericite and illite due to their association with coal mining.
 Two different sericite samples from different geographic locations were used
 in an insufflation experiment with rats.  The dust samples were split and half
 of the dust aliquot was treated with hydrochloric acid and then neutralized
 before administration to test animals.  The experiment ran for two months.
 Acid treated dust released silicilic acid in the lung with considerable ease,
 producing fibrous nodules in the test animals.  The untreated half of the dust
 produced only fibrous phagocytosis.13  Please remember that sericite and shale
 both contain substantial amounts of free silica.

      In 1953 and 1954 two articles appeared in literature describing medical
 examinations of 329 mica miners from Bihar, India and of dust exposures to
 61 mica factory workers in the same region; they processed crude mica.11* The
 exposure data on mica miners resembles those described by Dreessen in his
 North Carolina survey.  Mica processing and grinding exposures range from 44
 to 300 million particles per cubic foot with an average of 135 million particles
 per cubic foot.  The mica was muscovite, which contained less than 1% of free
 silica.  The environmental, as well as the previous work history, was not
 given.  The point was made that very few of the examined workers had been
 working with mica for more than 5 years.  Granulomas, found in the chest x-rays,
 were not beyond "ground glass II" reading.  Nodular or conglomerate fibrosis
 was not observed. ^

      The 1960's produced more research in physiology and pathology of the lung
 in the dusty trades.   In 1966, two Rumanians - Tripsa and Rotaru - published
 an article entitled "Experimental Studies in Pneumoconiosis Induced by Mica
 Dust."16  They introduced intratracheally into rats a one-time dose of 50 mil-
 ligrams of sized mica suspended in a saline solution.  They concluded that
 small mica particles below 6 microns in size travel to the hiliary lymph nodes,
 whereas the 20 to 25 micron particles remain lodged and display a higher patho-
 genicity.   They speculate that this particular observation may depend on mech-
 anical damage during the injection and irritative action, and therefore it
 might not  be correct.

      In 1962,  Vorwald and others published a report on an autopsy case of a
 rubber worker who during 33 years of employment was allegedly exposed for 21
 years to "soapstone"  dusting powder.   The autopsy lung specimen contained
 needle like  crystals.  The presence of both soapstone (fibrous talc) and bio-
 tite  was determined by x-ray diffraction.   The diagnosis was "fibrogenic
 pneumoconiosis induced by mica."17   The point in this case is perhaps the lack
 of  recognition for total combined impact,  not only the mica and the talc but
 all the  other  air contaminants which would be found in a rubber goods factory
 in  the  1940's  and 1950's.

      In  1968,  Lewis J.  Cralley and  others  published an article entitled "Source
and Identification of Respirable Fibers."1®  In it they discuss the autopsy
survey statistics  of  several  authors  indicating presence of fibrous bodies  in
the lungs of city dwellers.   Four to  six percent of those occupationally non-
separated autopsy  cases  described in  seven studies showed "numerous fibrous
bodies."  Cralley  and others  concluded that this finding was not a chance event.

                                      522

-------
The implication was that fibers are present in the lungs of city dwellers in
quantity.

     They further included a table of minerals with "fibrous-like structure"
taken from the text by Deer, Howie and Zussman.  This test was published in
1966.  In it, sheet silicates, specifically the mica group (muscovite) are
classified as having fibrous-like structure.   With regard to the mica group,
this may be an imprecise statement.  Structurally, true fibers are not found
in micas, except as impurities.  As you will see later, the fine particulates
associated with mica are bladed, play or lamellar in appearance.19

     In 1968, Mihajlov and Berova (in Bulgaria) published a paper which
describes the study of occupationally caused lesions associated with the pro-
duction of asbestos and mica.20  As only an abstract was available at the time
of writing this paper, the reported role of mica in occupational dermatoses
could not be determined.

     In 1969, Landwehr and Bruckmann in Germany in an article on mineral com-
position of pulmonary and suspended dusts, observe that secondary minerals
appear to inhibit or promote the effect of quartz in the lungs.  They speci-
fically mention iron hydroxide as an inhibitor and anthracite coal as a pro-
moter.21  This phenomenon was also observed by some Russian scientists who con-
ducted an experiment in 1975 with calcium hydroxide coated silica particles.22
The same inhibitory effect was also reported by G. Reichel and others in 1975
describing the findings of relative absence of silicosis in a large German
iron mine work population.23  These observations, if confirmed to be effective
also with mica dust, may diminish the risk of use of mica when mixed in a
chemically basic matrix.  A comparison experiment between the effect of pure
silica dust, pure muscovite dust and a mixture was performed by Starkov et al
at the Medical Institute in Irkutsk, USSR during 1970.2k  In a 12 month exper-
iment using rats, the researchers measured the increase in collagen in rat
lungs after a one-time administration of dust intratracheally.  The control
animals, exposed only to the intratracheal administration of the saline solution,
increased the lung collagen content by 2.5 percent over a period of 1 year.  This
probably represents normal aging.  The rats exposed to muscovite increased the
collagen content of the lungs by 4.4 percent, the mixed silica and mica dust
caused 5.5 percent increase and the administration of the pure quartz resulted in
9.9 percent of collagen increase in the lung in the same time frame.  They also
observed that the collagen increase in the lungs progressed more rapidly after
6 months of the dust administration.  This coincided with beginning of fibro-
blastic proliferation in the parenchyma of the lung.

     In 1972, J. M. G. Davis in Britain reported  on a  series of experiments
regarding the fibrogenic effect of mineral dust injected in the pleural  cavi-
ties of mice.25  One of the 16 materials used was chlorite, a  relative of  bio-
tite, "with a layered structure which in many ways resembles micas."  Mice were
administered an interperitonial 10 milligram one-time  dose.  All  materials
produced granulomas.  Granulomas were produced within  2 weeks  progressing  to
a fibrosis stage and these fibers gradually  being replaced by  collagen  in  a
period of 6 to 8 months.  This progression of  events perhaps on a different
time scale, is fairly characteristic of the  human experience.  To put it
plainly, inert dust in the interstitial spaces of the  lung  causes a very low

                                      523

-------
 level gathering of cells around the dust particle.  In a short time connective
 tissue is formed around the particle.  This tissue eventually hardens and
 becomes scar tissue.  Of course, I'm speaking of the particles which have not
 been removed by mucous and ciliary action.  The vast majority of inhaled par-
 ticles is removed in that fashion.  As a source of information, volume 200 of
 the Annals of New York Academy of Sciences, published in 1972 is entirely
 devoted to the lung and associated dust diseases.   It is an excellent refer-
 ence volume.

      In 1973, the Industrial Toxicology Center in Lucknow,  India, produced at
 least four papers on body fluid response to mica (muscovite).

      One paper describes the repeat of the collagen experiment conducted by
 Starkov et al. that the observations are histological and microscopic, rather
 than gravimetric.  The process of fibrogenesis, as reported by Davis, is
 confirmed.  The transport of dust particles in the lung lymphatic system is
 briefly discussed.  The authors also claim hemolysis of erythrocytes by mus-
 covite "in vitro."26  This finding has been challenged.

      Polyvinyl pyridine N-oxide was found to inhibit erythrocyte hemolysis
 "in vitro."2'  The solubility of kaolin, micas and talc in presence or absence
 of citrate, in buffer solution, defibrinated plasma and in serum is reported.28
 Solubility and concentration of silica and silicates in the lung has apparently
 a proportional negative influence on the enzymes which function in the lung.2^

      In 1974 Pott, Huth and Fredericks in Germany, conducted a test to deter-
 mine tumorigenic effect of fibrous dusts on rats.   They used the direct inter-
 peritoneal injection of dust suspended in saline solution.3^  Of the fifteen
 materials tested, only biotite and hematite did not produce tumors.  The dust
 "fiber" size was less than five microns.  The authors are convinced that dust
 induced carcinogenesis depends on the shape factor.  However, there were many
 unanswered problems regarding this hypothesis.

      Shanker and others reported on another experiment with Indian muscovite
 in 1975.31  The experimental animals in this case were guinea pigs.  The exper-
 imental design was focused on the lymphatic transport and the cytotoxic effect
 of mica in the lung.   The cytotoxic effect was not considered pronounced and
 the fibrotic lesions consisted of reticulin fibers (connective tissue).  The
 fibrogenic response was considered poor.  The experiment was of 1 year dura-
 tion after the intratradheal injection.

      In 1976,  in a French study,  Berry,  Henoc and others reported on the appli-
 cation  of  electron microscopy and electron micro-defraction in differentiating
 and  detecting  minerals  found in the  lungs of hospital patients.32  Of the 90
 cases reviewed,  50 had  a history of  pneumoconiosis.   In the cases associated
with silicoses,  muscovite and biotite were also present.

     A health hazard  evaluation was  conducted by NIOSH in 1976 in a mica paper
operation.33  The  complaint  was-nasopharyngeal irritation.   The causal relation-
ship between mica  and the symptomology present was suggestive but not conclusive.
                                      524

-------
     In 1975-76 the effects of phlogopite and muscovite dust in combination
with shellac and glythallic resin were studied in rats by Dianova and others
at the Moscow Medical Institute.3lf  The study lasted 12 months.   One group of
rats were intratracheally treated with 50 milligrams of either phlogopite,
muscovite, shellac or glythallic resin dust.   The other group received the
same doses of mica dust except 20 milligrams  of resin dust were added to each
dose to provide phlogopite/shellac,  phlogopite/glythallic resin, muscovite/
shellac and muscovite/glythallic resin exposure simulation.  When the animals
were sacrificed in the pure mica exposure group, internal organs such as liver,
heart and spleen showed uniform and  nominal changes indicating a low level of
irritation.  In the lung, granuloma  was observed, in the early stages in 12
months.  Shellac and resin dust caused a more pronounced hepatocytic reaction
in the liver and irritative reactions in the  lungs.

     The second group of animals (the combined materials) tested revealed that
the resin compound dust and shellac  dust have an inhibiting effect on formation
of collagen in the lung as compared  to mica exposure alone, even though aller-
genic or toxic effect on the rest of the body was more pronounced.

     A concurrent industrial hygiene and medical study in a micanite plant
indicated airborne dust concentrations of the tested materials between 8.5 and
134 milligrams per cubic meter.  Of  82 examined workers, 7 cases of pneumo-
coniosis were found.  At the same time 6 cases of chronic bronchitis and
3  cases of  lung calcifications were diagnosed.  As a result of  the  animal
study, a combined threshold limit value of 2  milligrams per cubic meter for
the activity is recommended.

     In 1977, Sedov and others from the Irkutsk Medical Institute describe a
study of 363 underground mica miners.35  The miners were exposed to dust con-
centrations up to 20 milligrams per cubic meter, peaking at 31 milligrams per
cubic meter.  Airborne free silica content is reported between 2 and 71 percent.
Twenty-nine cases of pneumoconiosis and two cases of tuberculosis were found.
All affected miners showed bilateral fine grain fibrosis.  Some had linear
thickening of the pleura.  The first x-ray findings came after 13 to 17 years
of underground work.  The authors conclude that pneumoconiosis develops after
a long period of time in the mines,  and is characterized by diffuse fibrosis,
weak desquamic bronchitis, emphysema and presence of mica particles in the
lungs.  The authors obviously are describing a mixed exposure situation.

     In 1978 two Portugese authors report a case of lung fibrosis complicated
by an enlarged liver which, upon autopsy, is found to contain sarcoidal granu-
lomas.  Both conditions are attributed to muscovite mica due to  7 years of
work history in mica grinding.36

     Finally in 1979 a fairly extensive article on silicate pneumoconiosis
appeared in the American pathological literature.  A simple pneumoconiosis
with lamellar birefringent crystals is reported by Brambilla et al,  observed
during the autopsies of animals which died in  the  San Diego Zoo.   In 100  autop-
sies of 11 mammaliam and 8 bird species,  interstitial fibrosis was present in
20 percent of the cases.  Seventy percent of  the particles analyzed in the
autopsy specimens were muscovite mica or  illite clay.   The mica was also
present in atmospheric air samples obtained in the zoo.   The  authors also report
similar mica induced lesions found in humans  living in the region of Southwest

                                      525

-------
 USA.  It is a well written article touching on the naturally occurring envi-
 ronmental exposures.37

      Finally, a recently released MSHA informational report (IR#1111) lists
 152 "minerals which may occur in fibrous habits or mineral suites which may
 contain minerals of a fibrous habit."38  Illite and sericite are included.
 Muscovite, biotite and phlogopite are not.

      To summarize the findings and impressions from the literature search
 conducted for this paper, I would like to make the following notes:

      (a)  Mica crystal lattice does not produce fibers even though some de-
           posits and products may contain fibers of other minerals as iia^_
           purities.  Mica produces bladed or platy particles when crushed
           or milled.

      (b)  Respirable mica particles trapped in the lung act as inert foreign
           bodies.  Generation of scar tissue results.  TLV for mica was set
           more than 20 years ago.  Other than conversion to gravimetric
           method of sampling, there has been no reason to change it.

      (c)  Experimentally pure mica dust produces less fibroses and at a
           slower rate than the mixed dust or quartz particles after an equal
           time and concentration exposure.

      (d)  Micas have not been reported to support tuberculosis in the lung.

      (e)  Micas have not been identified as carcinogenic, clinically or ex-
           perimentally.

      (f)  Granuloma and functionally noticeable fibrogenesis due to mica
           dust in humans is reported after very prolonged exposures to high
           concentrations of dust.  It almost has to be mixed occupational
           exposure.

      (g)  Judging from the employee exposures and airborne concentrations
           reported in the literature and from the medical survey data, the
           prevention of  fibrogenesis attributable to airborne mica dust
           should be relatively simple.

      (h)  The word "fibrous" should be used more judiciously.   In the con-
           text of the lungs,  it  means protective body reaction, not related
           to  the shape or nature of the offending particle.

      (i)   The speculation that coating  of the mica particles with other
          material,  especially chemically basic substances, inhibits fi-
          brogenesis should  be considered for experimentation.

     There were  a  dozen  references  which were mentioned in literature, but
were not available for the preparation  of this paper.
                                      526

-------
     Martin Marietta operates a phlogopite mine in Canada with a very large
and uniform deposit.  As the question of presence or absence of fibers had
to be resolved, we decided to perform a sampling experiment.  Seventeen trays
of exploratory core drillings were arbitrarily removed from storage and 1 to
2 inch sections were taken from each tray.  The samples were ground to 40
mesh size.  One electron microscope target was made from each ground sample.
Six photographs of each sample were produced by resetting the field selection
controls at random and refocussing.  Seventeen sets of such pictures were
produced.  None of the pictures showed the presence of fibers.  Magnification
was held at 2,000 times.  From the 17 sets,  3 were selected for presentation
today.  Ten foot, 152 foot and 342 foot levels were somewhat arbitrarily
chosen.  The six pictures in each set were reviewed for detail and clarity
and one was selected.  One centimeter on the photograph equals 5 microns
in actual dimension.  (See Appendix).  Some  flakes stand on edge and appear
acicular.

     We also photographed 12 commercial samples obtained from other mica
producers.  The fine residue in the sample bags was used to prepare the
electron microscope sample.  Again, a series of six views at random were
obtained.  The samples represent mica of the Soviet Union, Europe, India and
the United States.  The same selection technique as in our own core samples was
used for presentation selection.  Again we found no fibers.  We will grant
that the method used is somewhat cursory, however, with certain refinements
it can be used as a statistical tool to anticipate presence or absence of
fibers in a commercially useful ore body. We will endeavor to show all of
the photographs obtained in the survey to interested parties.

REFERENCES

 1.  Lefond, S. J. et al., Industrial Minerals and Rocks, American Institute
     of Mining, Metallurgical, and Petroleum Engineers, Inc., New York, NY,
     1975, pp. 837-50.

 2.  Documentation of the Threshold Limit Values for Substances in Workroom
     Air, American Conference of Governmental Industrial Hygienists,
     Cincinnati, Ohio, Third Edition, 1971.

 3.  Lefond, S. J. et al., op cit., p. 841.

 4.  Shevchenko, A. M. et al., On  the Mechanism of Lessening  the Fibrogenic
     Activity of Dust Processed with Calcium Hydroxide, Giglena Truda i
     Professionalniye Zabol., Vol. 21, No.  8, 1977,  (Russian;  short English
     abstract), pp. 31-34.

 5.  Zlobik, A. B., MICA-Mineral Commodity  Profiles,  U.S.  Bureau  of Mines*
     Pittsburgh, PA, 1979.

 6.  Zlobik, A. B., MICA, Minerals Yearbook, U.S.  Bureau of Mines,  1978-79.

 7.  Policard, A., The Action of Mica Dust  on Pulmonary Tissue, Journal of
     Industrial Hygiene, Vol. 15,  No.  3,  1934,  pp.  160-64.

                                     527

-------
  8.   Dreessen, W.  C.  et al.,  Pneumoconiosis Among Mica and Pegmatite Workers,
      U.S.  Public Health Bulletin, U.S.  Government Printing Office,  Washington,
      B.C., No. 250, 1940, pp. 1-74.

  9.   American Conference of Governmental Industrial Hygienists,  TLV's for
      Chemical Substances and Physical Agents in the Workroom Environment with
      Intended Changes for 1979^

 10.   Vestal, T. F. et al., Pneumoconiosis Among Mica and Pegmatite  Workers,
      Industrial Medicine, Vol. 12, 1943, pp. 11-14.

 11.   ACGIH, op cit.,  Documentation of the Threshold Limit Values for Substances
      in Workroom Air.

 12.   Smith, Adelaide  R., Pleural Calcification Resulting from Exposure to
      Certain Dusts, American Journal of Roentgenology, Vol. 67,  1952,
      pp. 375-382.

 13.   King, E.  J. et al., Tissue Reaction to Sericite and Shale Dusts Treated
      With Hydrochloric Acid;   An Experimental Investigation on the  Lungs of
      Rats, Journal of Pathology and Bacteriology, Vol. 59, 1947, pp. 324-27.

 14.   Silicosis in Mica Mining in Bihar, India, Monthly Review of the Division
      of Industrial Hygiene,  New York State Department of Labor,  Vol. 33,
      No. 7, 1954,  pp. 25-28.

 15.   Heimann,  H.,  et  al., Note on Mica Dust Inhalation, Archives of Industrial
      Hygiene and Occupational Medicine, Vol. 8, No. 6, 1953, pp. 531-32.

 16.   Tripsa, R., et al., Experimental Studies^ on Pneumoconiosis  Induced by
      Mica  Dust, Medicina Del Lavoro, Vol.  57; No. 8-9, 1966, French; English
      summary), pp. 492-500.

 17.   Vorwald,  A. J. et al., Mineral Content of Lung in Certain Pneumoconioses,
      Archives  of Pathology,  Vol.  74, 1962, pp. 17-24.

 18.   Cralley,  Lewis J., et  al.,  Source  and Identification of Respirable
      Fibers, American Industrial  Hygiene Association Journal,  Vol.  29,
      1968,  pp.  129-135.

 19.   Campbell,  W.  J.  et al.,  Selected Silicate Minerals and Their Asbestiform
      Varieties,  United  States Department of the Interior,  Bureau of Mines,
      Information Circular 8751,  1977, p.  27.

 20.  Mihajlov,  P.,  et al., Occupational Lesions Associated with  the Production
      and Processing of  Asbestos and Mica,  Higiena i Zdraveopazvane, Vol. 11,
      No. 2,  1968,  (Bulgarian), pp.  145-150.

21.  Bruckman,  E., et al., The Mineral  Composition of Pulmonary  and Suspended
     Dusts  and  Their  Silicogenic  Effect,  Staub-Reinhalt,  Luft, Vol. 29, No.  1,
    *>January 1979,  (English Ed.),  pp. 6-17.


                                     528

-------
22.  Schevchenko,  A.  M.  et al.,  op cit.

23.  Reichel, G.,  et al.,  The Action of  Quartz in the Presence of Iron
     Hydroxides in the Human Lung, Inhaled Particles, IV,  1975, pp.  403,
     408-410.

24.  Starkov, M.  V. et al., Biochemical  and Morphological  Evaluation of
     Collagen Generation in the  Lungs (of Experimental Animals) Caused by
     Mica and Mixed Dust from Mines in Irkutsk Region, Gigiena Truda i
     Professionalniye Zabol., Vol. 15, No. 8,  (Russian), 1971, pp.  42-43.

25.  Davis, J. M.  G., The Fibrogenic Effects of Mineral Dusts Injected into
     the Pleural Cavity of Mice, British Journal of Experimental Pathology,
     Vol. 53, 1972, pp.  190-201.

26.  Raw, J. L. et al.,  Effect of Mica Pust^on the Lungs of Rats,
     Experimentalle Pathologie,  Vol. 8,  No. 3, 1973, (Jena, E. Germany),
     pp. 224-231.

27.  Kaw, J. L. et al.,  Hemolytic Activity of Mica Dust and Its Relation to
     Polyvinylpuridine N-Oxide,  Experimentalle Pathologie, Vol. 8,  No. 5-6,
     1973,  (Jena,  E.  Germany), pp. 349-355.

28.  Rahman, Qamar et al., Solubility of Kaolin, Talc and  Mica Dusts Under
     Physiological Conditions, Environmental Physiology and Biochemistry,
     Vol. 3, No.  6, pp.  286-294.

29.  Rahman, Qamar et al., Relation Between Solubility of  Silicates and
     Enzyme Inhibition in Rat Lung Homogenate (in Vitro Studies), Environ-
     mental Physiology and Biochemistry, Vol.  3, No. 6, 1973, pp. 281-285.

30.  Pott, F. et al., Tumorigenic Effect of Fibrous Dusts  in Experimental
     Animals, Environmental Health Perspectives, Vol. 9,  1974, pp.  313-315.

31.  Shanker, R.  et al., Effect of Intratracheal Injection of Mica Dust  on
     the Lymph Nodes of Guinea Pigs, Toxicology, Vol. 5,  1975, pp. 193-199.

32.  Berry, J. P.  et al., Pulmonary Mineral Dust, American Journal of
     Pathology, Vol. 83, No. 3,  1967. pp. 427-456.

33.  National Institute for Occupational Safety and Health, Health Hazard
     Evaluation Determination, U.S Department of Commerce, NTIS, Report
     No. 75-193-335, 1976, pp. 1-16.

34.  Dianova, A. V. et al., The Problem of the  Combined Action of the Dust
     of Mica and Resins Used in the Production Micanite Articles, Gigiena i
     Sanitarnaya, Vol. 7, 1976, (Russian;  English  summary), pp.  33-37.
                                     529

-------
35.  Sedov, K. R. et al., The Morphological Characterization of Mica
     Pneumoconiosis in a Mine in the Irkutsk Region, Gigiena Truda i
     Professionalniye Zabol., Vol. 21, No. 2, 1977, (Russian), p. 48.

36.  Pimentel, I. C. et al., Pulmonary and Hepatic Granulomatous Disorders
     Due to the Inhalation of Cement and Mica Dusts, Thorax, Vol. 33, No. 2,
     1978, pp. 219-227.

37.  Brambilla, C. et al., Comparative Pathology of Silicate Pneumoconiosis,
     American Journal of Pathology, Vol. 96, No. 1, 1979, pp. 149-170.

38.  Asbestiform and/or Fibrous Minerals in Mines, Mills and Quarries,
     U.S Department of Labor, Mine Safety and Health Administration,
     Informational Report IR 1111, 1980.
                                     530

-------
APPENDIX
   531

-------
MARTIN MARIETTA CORPORATION
          PHLOGOPITE -  CANADIAN  - CORE SAMPLE 152 FT. LEVEL

-------
                                         MARTIN MARIETTA CORPORATION
Ln
                                                   PHLOGOPITE  -  CANADIAN  -  CORE SAMPLE 10 FT. LEVEL

-------
                        MARTIN MARIETTA CORPORATION
01
UJ
                                 PHLOGOPITE -  CANADIAN - CORE SAMPLE 342  FT.  LEVEL

-------
                           MARTIN MARIETTA CORPORATION
v£>
                                                      PHLOGOPTTE - USSR

-------
MARTIN MARIETTA CORPORATION
                          MUSCOVITE  -  EUROPEAN

-------
                       MARTIN MARIETTA CORPORATION
en
                                                 MUSCOVITE - INDIA

-------
                          MARTIN MARIETTA CORPORATION
en
x-
                                            MUSCOVITE - INDIA - MICRONTZED

-------
MARTIN MARIETTA CORPORATION
                      MUSCOVITE - NORTH CAROLINA

-------
                        MARTIN MARIETTA CORPORATION
vO
                                        MUSCOVITE - NORTH  CAROLINA - FINE GRIND

-------
MARTIN MARIETTA CORPORATION
              MUSCOVITE  -  NORTH CAROLINA - COARSE GRIND

-------
                        MARTIN MARIETTA CORPORATION
ui
en
U)
                                         MUSCOVITE  -  SOUTHERN NORTH CAROLINA

-------
                             DISCUSSION ON MICA

QUESTION  (Mr. Stumpf):  I am from U.S. Mineral Products.  I noticed in
          your chart, from one of the micas, that you reference vermiculite,
          which I understand at times does have some fibers.  You indicate
          that your Canadian mica contained no fibers.  Are fibers associated
          with some of the other micas and in what part of the United States?

ANSWER    (Mr. Lusis):  I really cannot answer that truthfully.  My personal
          knowledge of the presence of particulates in mica is restricted
          to the 156 electronmicroscope slides which I observed.

          In reviewing the literature, I did see a couple of pictures,
          especially in the foreign literature, which would claim to be mica
          and there would be a few particles in them.  But in the cursory
          survey we did here and from a rough statistical point of view, I
          am fairly well convinced that in the U.S. markets of the ground
          micas., you have to go back to the manufacture process.  Most of
          U.S. ground mica is washed before you get it.  That is part of
          the separation process of kaolin; you take kaolin out and then
          you get some mica from it.  So, again, in some European micas
          you could get fibers; but from the commercial samples we re-
          ceived, I did not see any.
                                    554

-------
                         HEALTH  EFFECTS OF VERMICULITE

                                       by

                   Dr. James Lockey and Dr. Stuart M.  Brooks*
                 University of Cincinnati College of Medicine
                               Cincinnati, Ohio
                                    ABSTRACT

    Vermiculite is a geologic name given to a group of hydrated laminar minerals
    which are aluminum-iron magnesium silicates resembling mica in appearance.
    When subjected to heat it has the unusual property of exfoliating or  expand-
    ing due  to the interlaminar  generation of steam.  The present study includes
    an analysis of the physical  and chemical characteristics of vermiculite;  an
    industrial hygiene survey of a plant which utilized crude vermiculite in  an
    industrial process; and the  results of some preliminary information on a
    cross-sectional morbidity study of exposed workers.

    Depending on source location raw vermiculite may be contaminated with
    tremolite-actinolite asbestos.  Contamination is greatest in vermiculite
    obtained from Montana and least from vermiculite obtained from South  America.
    Preliminary investigations of workers suggest a high prevalence rate  of
    pleural  and possibly parenchymal lung disease.  There were nine employees
    identified with benign pleural effusions, believed to be on an occupational
    basis.  It appears that adverse health effects from vermiculite are  the
    results  of contamination with tremolite-actinolite asbestos and not  related
    to vermiculite itself.
     This  report will review various physical and chemical properties  of
vermiculite, and present  preliminary data  on a me