United States
Environmental Protection
Agency
Industrial Environmental Research EPA 600 2-79-210c
Laboratory December 1 979
Cincinnati OH 45268
Research and Development
Status
Assessment of
Toxic Chemicals
Asbestos
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1 Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7 Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ENVIRONMENTAL PROTECTION TECH-
NOLOGY series. This series describes research performed to develop and dem-
onstrate instrumentation, equipment, and methodology to repair or prevent en-
vironmental degradation from point and non-point sources of pollution. This work
provides the new or improved technology required for the control and treatment
of pollution-sources to meet environmental quality standards.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/2-79-210c
December 1979
STATUS ASSESSMENT OF TOXIC CHEMICALS:
ASBESTOS
by
S. R. Archer
T. R. Blackwood
Monsanto Research Corporation
Dayton, Ohio 45407
Contract No. 68-03-2550
Project Officer
David L. Becker
Industrial Pollution Control Division
Industrial Environmental Research Laboratory
Cincinnati, Ohio 45268
INDUSTRIAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
-------
DISCLAIMER
This report has been reviewed by the Industrial Environmental
Research Laboratory - Cincinnati, U.S. Environmental Protection
Agency, and approved for publication. Approval does not signify
that the contents necessarily reflect the views and policies of
the U.S. Environmental Protection Agency, nor does mention of
trade names or commercial products constitute endorsement or
recommendation for use.
XI
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FOREWORD
When energy and material resources are extracted, processed,
converted, and used, the related pollutional impacts on our
environment and even on our health often require that new and
increasingly more efficient pollution control methods be used.
The Industrial Environmental Research Laboratory - Cincinnati
(lERL-Ci) assists in developing and demonstrating new and
improved methodologies that will meet these needs both effi-
ciently and economically.
This report contains a status assessment of the air
emissions, water pollution, health effects, and environmental
significance of phosphates. This study was conducted to provide
a better understanding of the distribution and characteristics
of this pollutant. Further information on this subject may be
obtained from the Organic Chemicals and Products Branch,
Industrial Pollution Control Division.
Status assessment reports are used by lERL-Ci to communi-
cate the readily available information on selected substances to
government, industry, and persons having specific needs and
interests. These reports are based primarily on data from open
literature sources, including government reports. They are
indicative rather than exhaustive.
David G. Stephan
Director
Industrial Environmental Research Laboratory
Cincinnati
in
-------
ABSTRACT
Asbestos, occurring naturally as a component of many soils, is
a suspected carcinogen found in air, water, and food in various
amounts in all parts of the United States.
In 1974, a total of 102,071 metric tons of asbestos were ex-
tracted from mines in California, Vermont, Arizona, and North
Carolina. There are approximately 3,000 uses of asbestos in
various industries, including construction, floor tiles, tex-
tiles, papers, plastics, friction products, and insulation. A
total of 659 plants in these industries fabricate asbestos into
a variety of products.
Asbestos enters the environment from so many sources that its
presence may be regarded as ubiquitous, with only a small portion
of the fibers arising from natural sources. Available data indi-
cate that urban levels due to industrial sources, brake lining
residues, and other sources, averaging 29 ng/m3, are much greater
than nonurban concentrations, which generally appear to be less
than 1 ng/m3. Mining and milling appear to result in the ma-
jority of atmospheric emissions, while asbestos fabrication in
the construction industry results in the major asbestos water
discharges. Maximum atmospheric asbestos concentrations have
been calculated using industry data, and indications are that
the maximum concentration of 6.2 x 10~9 g/m3 will extend 1 km
from an average operating asbestos plant (covering 2,060 km2),
and will fall off inversely with the square of further distances
from the sources. Asbestos has been found in potable drinking
water supplies ranging in concentration from 0.25 x 103 fibers/m3
to 240 x 103 fibers/m3, but no firm evidence is available re-
garding the hazard to man from waterborne asbestos.
Asbestosis (fibrosis of the lung) and pulmonary cancer are asso-
ciated with mining and milling of asbestos and manufacturing
asbestos products. Such emissions have been greatly reduced
from previous levels, even though production and consumption of
asbestos products has increased, due to enforcement of regula-
tions under the Clean Air Act of 1970. Visible emissions from
manufacturing operations have been prohibited, demolition opera-
tions are more strictly controlled, disposal of asbestos-con-
taminated wastes is regulated, and waste dump operations are
specified to minimize dispersion of fibers into the environment.
IV
-------
The discovery of association of a unique tumor with very low-
level exposure, or with casual contact with one form of asbestos,
indicates that there may not be a safe level for this asbestos
form. However, at this point there is no evidence of cancer risk
to the general public from asbestos in air, water, beverages,
or food.
Asbestos has been the subject of a variety of studies to deter-
mine standards for drinking water, air, workplace, and mine
safety. An air standard has been promulgated for a number of
major commercial sources of asbestos fibers. Effluent guidelines
have been promulgated under the Federal Water Pollution Control
Act which, together with the National Pollutant Discharge Emis-
sion System (NPDES) permit program, should reduce asbestos
discharges.
A number of studies have been conducted involving the environ-
mental consequences of the production and use of asbestos fibers
and the incidental release as a result of other industrial pro-
cesses which use asbestos as a feedstock or which contain it as an
impurity. A significant amount of information has been collected
on the use of asbestos in a wide range of industrial and house-
hold products. Environmental assessments have been and are being
conducted for those industries which use significant amounts of
asbestos. These include analyses of production processes, waste
streams and control technologies. Research has been completed
which documents the actual mass and fractional efficiency of
baghouses, the predominately used control device. Research is
continuing on the optimum use and maintenance of control devices
to control asbestos emissions. More definite information con-
cerning emission sources, environmental behavior and persistence,
and health effects of long-term low-level exposure of airborne
and waterborne asbestos is needed.
This report was submitted in partial fulfillment of Contract
68-03-2550 by Monsanto Research Corporation under the sponsorship
of}the U.S. Environmental Protection Agency. This report covers
the period November 1, 1977 to December 31, 1977. The work was
completed as of January 20, 1978.
v
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CONTENTS
Foreword iii
Abstract iv
Tables vii
Conversion Factors and Metric Prefixes .' viii
Acknowledgement ix
1. Introduction 1
2. Summary 2
3. Source Description 5
Physical and chemical properties 5
Production 5
Process description 5
4. Environmental Significance and Health Effects .... 11
Environmental significance 11
Health effects 14
5. Control Technology 16
6. Regulatory Action 19
References 21
TABLES
Number Page
1 Asbestos 3
2 Properties of Six Asbestos Forms . 6
3 U.S. Asbestos Mines 8
4 U.S. Asbestos Uses 9
5 Asbestos Distribution by End Use and Type, 1974. . 10
6 Asbestos Products Industry Air Emissions and
Surrounding Populations 13
7 Asbestos Emission Factors for Various Sources. . . 13
8 Asbestos Products Industry Control Costs
(1970 Dollars) 17
vii
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CONVERSION FACTORS AND METRIC PREFIXES
CONVERSION FACTORS
To convert from
Degree Celsius (°C)
Joule (J)
Kelvin (K)
Kilogram (kg)
Kilometer2 (km2)
Meter (m)
Meter2 (m2)
Meter3 (m3)
Meter3 (m3)
Metric ton
Siemens (S)
to
Degree Fahrenheit
British thermal unit
Degree Celsius
Pound-mass (pound-mass
avoirdupois)
Mile2
Foot
Foot2
Foot3
Gallon (U.S. liquid)
Pound-mass
Mho
Multiply by
t£ = 1.8 t° + 32
9.479 x 10-*
t° = t° - 273.15
2.204
3.860 x 10"1
3.281
1.076 x 101
3.531 x 101
2.642 x 102
2.205 x 103
1.000
METRIC PREFIXES
Prefix Symbol Multiplication factor
Kilo
Centi
Micro
Nano
k
c
y
n
103
10~2
10~6
ID"9
Example
Ikg=lxl03 grams
1 cm = 1 x 10~2 meter
1 ym = 1 x 10~6 meter
1 ng = 1 x 10"9 gram
Standard for Metric Practice. ANSI/ASTM Designation:
E 380-76S IEEE Std 268-1976, American Society for Testing and
Materials, Philadelphia, Pennsylvania, February 1976. 37 pp.
Vlll
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ACKNOWLEDGEMENT
This report was assembled for EPA by Monsanto Research
Corporation, Dayton, OH. Mr. D. L. Becker served as EPA Project
Officer, and Dr. C. E. Frank, EPA Consultant, was principal
advisor and reviewer.
IX
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SECTION 1
INTRODUCTION
Asbestos, a naturally occurring component of many soils, is a
suspected human carcinogen found in air, water, and food in
varying amounts in all parts of the United States. Besides the
natural release to the environment from wind and water erosion
of asbestos-bearing formations, there are several types of man-
made emissions, including those from mining and milling asbestos
ores, consumptive use to manufacture asbestos products, wear or
consumption of asbestos-containing products, and release of
asbestos incidental to other industrial or commercial processes.
Exposure to asbestos fibers may occur throughout urban environ-
ments, and asbestos fibers have been found in a number of
drinking water supplies; thus there is concern about adverse
health effects to the general population.
There is a need to define the various sources from which asbes-
tos may enter the environment, to establish consequent health
and environmental effects, and to examine possible control
strategies and present regulatory actions. This report provides
a brief overview describing these items with emphasis on asbes-
tos sources and their environmental significance.
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SECTION 2
SUMMARY
Asbestos is the name applied to a number of fibrous mineral
silicates found naturally in irregular veins scattered throughout
rock masses in various parts of the world.
Total 1974 U.S. asbestos output was 102,071 metric tons from
mines located in four states: California, Vermont, Arizona, and
North Carolina. Asbestos is often mined by trenching or open-pit
methods, followed by underground mining by tunneling or block-
caving methods. Milling practice, essentially a dry screening
operation, consists of multiple stages of crushing, screening,
aspirating the fiber from the rock, sifting, recleaning the
fiber, and grading.
There are approximately 3,000 uses of asbestos in various indus-
tries. Its greatest use is in the manufacture of asbestos cement
products; its second largest use is in asphalt and vinyl floor
tiles. Other industries using asbestos include textiles, elec-
trical equipment, papers, plastics, felts, and friction materials.
Asbestos enters the environment from so many sources that its
presence may be regarded as ubiquitous. Table 1 presents avail-
able information concerning emission sources, emission quantities,
population exposed, pollution control technology, and regulatory
agencies and actions.
Available data indicate that urban levels of asbestos in air,
averaging 29 ng/m3, are much greater than nonurban concentra-
tions, averaging less than 1 ng/m3, due to industrial emission
sources, brake lining residues, and other sources such as build-
ing construction and demolition. Recent evidence indicates that
asbestos is leached from asbestos-cement pipes in municipal water
systems. In 1975, asbestiform fibers were found in 10 widely
separated potable water supplies, ranging in concentration from
0.25 x 103 fibers/m3 to 240 x 103 fibers/m3.
The association of impaired human health with industrial exposure
to asbestos is well known. Asbestosis (fibrosis of the lung) and
al metric ton = 106 grams; conversion factors and metric system
prefixes are presented in the prefatory pages of this report.
2
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TABLE 1. ASBESTOS
Extent
of problem
Disposal quantity,
metric tons/yr, 1972
Emission source
Production:
Mining
Milling
Fabrication:
Construction
Pelts and paper
Floor tile
Friction products
Gaskets and
packing
Insulation
Textiles
Other
Consumption :
Construction
Felts and paper
Floor tile
Friction products
Gaskets and
packing
Insulation
Textiles
Other
Air
597
1,194
153
53
38
210
14
18
7
54
5u
b
Ib
b
37
_b
_b
Water
_b
48
246
42
4
21
2
4
1
5
_b
_b
_b
_b
28
_b
_b
_b
Landa
53,288
5,045
1,536
527
385
350
140
89
35
535
6,804
2,631
11,521
69,382
27,779
443
6,963
53,115
Population
density,
persons/km2
b
_b
1,720
1,687
2,960
2,507
c
~c
2,203
2,300
b
~b
"b
"b
b
~b
~b
"b
Control method Regulatory agency or action
Fabric filters during drilling. Drinking water standard - National
Cyclones, bag collectors, and ducts for Academy of Sciences study of health
dust control in crushing operation effects of asbestos in drinking
Cyclones, possibly followed by bag- water.
houses used on dryers
All conveyors generally covered, low Hazardous air pollutant standard -
velocity hoods in other areas. Iron ore beneficiation plants being
studied to determine possible
Fabric filters (baghouses) coverage of current Hazardous Air
Pollutant Standards.
Workplace standard - Proposed down-
ward revision of workplace exposure
limit .
Workplace studies - Brake lining and
clutch rebuilding industries being
studied to determine best means of
worker protection.
Mine safety standard - Possible
revision of mine safety standard
for asbestos .
Priority pollutant - asbestos is
listed as a priority pollutant
under the Federal Water Pollutant
Control Act.
Includes residual solid waste.
Not available.
f* O
Combined population density for gaskets, packing, and insulation equals 2,800 persons/km .
-------
pulmonary cancer are associated with mining and milling of as-
bestos and manufacturing asbestos products. The discovery of
association of a unique tumor with very low-level exposure, or
with casual contact with one form of asbestos, indicates that
there may not be a safe level for this asbestos form. However,
at this point there is no evidence of cancer risk to the general
public from asbestos in air, water, beverages, or food.
Fabric filters (baghouses) have been found to be the most effec-
tive method of controlling asbestos emissions from manufacturing
processes. In asbestos mining, small fabric filters are used for
control during drilling. Cyclones, bag collectors, and properly
designed ducts are then used for dust control in the crushing
operation. Cyclones, sometimes followed by baghouses, are used
as control devices on dryers.
An air standard has been promulgated for a number of major com-
mercial sources of asbestos fibers. Effluent guidelines have
been promulgated which, together with the National Pollutant
Discharge Elimination System (NPDES) permit system, should reduce
asbestos discharges. Additional regulatory actions, control
options, and attendant impacts concerning asbestos are shown in
Table 1.
Based on the information presented in this report, the following
items need to be considered in future studies:
• long-term low-level health effects of airborne and
waterborne asbestos.
• environmental behavior and persistence of asbestos.
• rates of emissions and effluents from mining, fabrication
and consumption processes.
• possibility of asbestosis or cancer risk to the general
public from asbestos in air, water, food, and beverages.
-------
SECTION 3
SOURCE DESCRIPTION
Asbestos, the name applied to a number of fibrous mineral sili-
cates, is found naturally in irregular veins scattered throughout
rock masses in various parts of the world. The silicates may be
divided into two large groups, one called serpentine (chrysotile)
and the other amphibole which contains the minerals anthophyllite,
amosite (ferroanthophyllite), crocidolite, tremolite, and
actinolite.
PHYSICAL AND CHEMICAL PROPERTIES
Physical and chemical properties of various forms of asbestos
differ considerably. Table 2 summarizes the properties of six
varieties of asbestos (1).
PRODUCTION
Total asbestos output from United States mines was 102,071 metric
tons in 1974 (2). Asbestos was produced in four states in 1974;
California, with 53% of production, was the leader, followed in
order by Vermont, Arizona, and North Carolina. Table 3 presents
a listing of asbestos mines, locations, and types of asbestos
mined in 1974.
PROCESS DESCRIPTION
Mining of asbestos is often done by trenching or open-pit
methods, followed by underground mining by tunneling or block-
caving methods. Milling practice, essentially a dry screening
operation, consists of multiple stages of crushing, screening,
aspirating the fiber from the rock, sifting, recleaning the
fiber, and grading. Recleaning methods have been adopted to
eliminate most dust and improve fiber grade quality. Huge bag-
house installations have improved working conditions by reducing
(1) Kirk-Othmer Encyclopedia of Chemical Technology, Second
Edition, Vol. 2. John Wiley & Sons, Inc., New York, New
York, 1963. pp. 734-747.
(2) Clifton, R. A. Asbestos. In: Minerals Yearbook, 1974;
Vol. 1: Metals, Minerals, and Fuels. U.S. Department of
the Interior, Washington, D.C., 1976. pp. 179-189.
-------
TABLE 2. PROPERTIES OF SIX ASBESTOS FORMS (1)
Structure
Mineral association
Origin
Veining
Essential
composition
Crystal structure
Crystal system
Color
Chrysotile
in veins of serpentine,
etc.
in altered peridotite
adjacent 'to serpen-
tine, and limestone
near contact with
basic, igneous rocks
alternation and meta-
morphism of basic
igneous rocks rich in
magnesian silicates
cross and slip fibers
hydrous silicates of
magnesia
fibrous and asbesti-
form
monoclinic (pseudo-
orthorhombic? )
white, gray, green,
yellowish
Anthophyllite
lamellar, fibrous
asbestiform
in crystalline
schists and
gneisses
metamorphic, usually
from olivine
slip, mass fiber
unoriented and
interlacing
magnesium silicate
with iron
prismatic, lamellar
to fibrous
orthorhombic
grayish white,
brown , gray , or
green
Amosite
( f erroanthophy llite }
lamellar,, coarse to
fine fibrous and
asbestiform
in crystalline
schists, etc.
metamorphic
cross fiber
silicate of iron and
magnesium, higher
iron than antho-
phyllite
prismatic, lamellar
to fibrous
monoclinic
ash gray, greenish,
or brown
Crocidolite
fibrous in iron-
stones
in iron-rich sili-
ceous argillite
in quartzose
schists
regional metamor-
phism
cross fiber
silicate of sodium
and iron with
some water
fibrous
monoclinic
lavender, blue,
greenish
Tremolite
long, prismatic and
fibrous aggregates
in Hg limestones as
alteration product
of highly magnesian
rocks, metamorphic
and igneous rocks w
metamorphic
slip or mass fiber
.calcium and magnesium
silicate with some
water
long and thin colum-
nar to fibrous
monoclinic
gray-white , greenish ,
yellowish, bluish
Actinolite
reticulated long
prismatic crys-
tals and fibers
in limestone and in
crystalline
schists
results of contact
metamorphism
slip or mass fiber
calcium, magnesium,
iron, silicates,
water up to 5%
long and thin
columnar to
fibrous
monoclinic
greenish
Luster
silky
vitreous to pearly vitreous, somewhat silky to dull
pearly
silky
silky
(continued)
-------
TABLE 2. (continued)
Chrysotile
Anthophyllite
Amosite
(ferroanthophy1lite)
Crocidolite
Tremolite
Aotinolite
Hardness, S
Specific gravity
Cleavage
Optical properties
Refractive index
Fusibility,
Seger cones
Flexibility
Length
Texture
Acid resistance
Spinnability
Specific heat,
-J/kg-K
2.5 - 4.0
2.4 - 2.6
010 perfect
biaxial positive ex-
tinction parallel
1.50 - 1.55
fusible at 6,
1,190°- 1,230°C
very flexible
short to long
soft to harsh, also
silky
soluble up to approxi-
mately 57%
best
946
5.5 - 6.0
2.85 - 3.1
110 perfect
5.5 - 6.0
3.1 - 3.25
110 perfect
3.2 - 3.3
110 perfect
5.5
2.9 - 3.2
110 perfect
biaxial positive ex- biaxial positive ex-
tinction parallel tinction parallel
biaxial extinction biaxial negative ex-
inclined tinction inclined
1.61
infusible or diffi-
cultly fusible
very brittle, non-
flexible
short
harsh
1.64
fusible at 6, loses
water at moderate
temperatures
good, less than
Chrysotile
5 cm to 30 cm
varies
coarse but somewhat
pliable
1.7 pleochroic
1.61
fairly resistant to fairly resistant to
acids acids
fusible at 3, fusible a* 4,
1,145° - 1,170°C 1,165° - 1,1900C
fair to good generally brittle,
sometimes flexible
short to long short to long
soft to harsh generally harsh,
sometimes soft
fairly resistant to fairly resistant to
acids acids
poor
fair
fair
879
908
841
generally poor, some
are spinnable
888
3.0 - 3.2
110 perfect
biaxial negative
extinction
inclined
1.63 weakly
pleochroic
fusible at 4,
1,165° - 1,190°C
brittle and non-
flexible
short to long
harsh
relatively insolu-
ble in HC1
poor
908
Kirk-Othmer Encyclopedia of Chemical Technology, Copyright (C) 1963. Reproduced
with permission of the Canadian Institute of Mining and Metallurgy and John Wiley
and Sons, Inc.
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TABLE 3. U.S. ASBESTOS MINES
State and company
Arizona: Jaquays Mining Corp.
California:
Atlas Asbestos Corp.
Coalinga Asbestos Co., Inc.
Pacific Asbestos Corp.
Union Carbide Corp.
North Carolina:
Powhatan Mining Co.
Vermont: GAP Corp.
County
Gila
Fresno
Fresno
Calaveras
San Benito
Yancey
Orleans
Name of mine
Chrysotile
Santa Cruz
Christie
Pacific Asbestos
Santa Rita
Hippy
Lowell
Type of
asbestos
Chrysotile
Chrysotile
Chrysotile
Chrysotile
Chrysotile
Anthophyllite
Chrysotile
Closed at end of 1974.
dusts in the mills and recirculating the clean filtered air back
into the working areas. Baghouse dusts are also graded and sold
as fillers. Most fibers are pressure-packed ready for shipment,
thus improving warehousing and shipping facilities (1).
USES
The greatest use of asbestos is in the manufacture of asbestos
cement products made primarily by wet processes. The second
largest use of asbestos is in asphalt and vinyl floor tiles.
Asbestos is used in a variety of industries as shown in Table 4,
which shows the diversity of products in which asbestos may be
used. A total of 659 plants have been identified in the various
industries shown (3).
In 1974, 12% of all asbestos consumed in the United States was
produced in U.S. mines, the rest being imported. Chrysotile is
by far the most commonly used form of asbestos, accounting for
over 94% of U.S. consumption in 1974. Most Chrysotile fibers
are used in manufacturing asbestos cement pipes, asbestos cement
sheets, and flooring products as shown in Table 5 (2). Primary
Chrysotile uses include friction products, sealants, sidings,
tiles, guttering, and waste pipes for the construction industry.
From Table 5, crocidolite is the next most commercially important
form of asbestos. It is used primarily in the construction
(3) Moll, K., S. Baum, E. Capener, F. Dresch, R. Wright,
G. Jones, C. Starry, and D. Starrett. Hazardous Wastes.
A Risk-Benefit Framework Applied to Cadmium and Asbestos
(PB 257 951). U.S. Environmental Protection Agency,
Washington, B.C., September 1975. 272 pp.
8
-------
TABLE 4. U.S. ASBESTOS USES (3)
Asbestos - cement industry:
Shingles for roofing and siding
Wall sheets
Insulation board
Clapboard
Electric motor casings
Water and sewage pipes
Gas pipes
Rain gutters
Air ducts
Refuse chutes
Asbestos - textile industry:
Fireproof theater curtains
Lagging
Other insulation wrapping
Conveyor belting
Safety clothing
Potholders
Ironing board covers
Draperies
Rugs
Motion picture screens
Gas filters in gas masks
Filters for processing fruit
juices
Filters for processing acids
Filters for processing beer
Filters for processing medicine
Mailbags
Prison-cell padding
Airplane fittings
Stove and lamp wicks
Sparkplugs
Fire hose
Electrical equipment industry:
Insulation tape
Asbestos papers, felts, and millboard:
Roofing
Piano padding
Stove and heater linings
Filing cabinet linings
Military helmet linings
Automobile hood mufflers
Boiler jackets
Radiator covers
Acoustical ceilings
Plasterboard
Fireproof wallboard
Electrical switch boxes
Safes
Table pads
Stove mats
Ovens
Dry kilns
Asbestos plastics:
Flooring tiles (asphalt and vinyl
binders)
Reinforcement and filler in plastics
Plastic products (frying-pan handles,
rocket nose covers)
Miscellaneous:
Ingredient of paints and sealants
Component of roof coating and road-
building compounds
Putty, caulk, and other crack fillers
Artificial snow
Spray insulation on structural steel
Undercoating on automobile bodies
Gaskets and packing materials
Insulation materials
Friction materials:
Brake linings
Clutch facings
-------
TABLE 5. ASBESTOS DISTRIBUTION BY END USE AND TYPE, 1974 (2)
Asbestos type, metric tons
End use
Antho- Total
Chrysotile Crocidolite Amosite phyllite asbestos
Asbestos cement pipe
Asbestos cement sheet
Flooring products
Roofing products
Packaging and gaskets
Insulation, thermal
Insulation, electrical
Friction products
Coatings and compounds
Plastics
Textiles
Paper
Other
TOTAL
167,980
82,090
139,230
66,940
26,030
6,620
4,260
72,200
34,380
15,330
18,500
57,230
33,020
723,810
33,020
_a
-
-
90
-
-
-
-
180
-
180
360
33,830
1,000
3,900
-
1,540
-
1,630
-
-
-
-
-
-
450
8,520
180
-
-
-
-
-
-
180
-
630
-
-
-
1,000
202,180
85,990
139,230
68,480
26,120
8,250
4,260
72,380
34,380
16,140
18,500
57,410
33,830
767,160
i
Not applicable.
trades and the manufacture of paper, acid-resistant gaskets,
filters, and marine insulation. Amosite and then anthophyllite
rank below crocidolite in commercial importance. Amosite is
used primarily for construction industry products, roofing pro-
ducts, and thermal insulation. Anthophyllite is used as a filler
in plasticware and to a lesser extent in construction industry
products and friction products.
Asbestos was used in spray insulation in buildings between 1950
and 1972. This may become a major source of environmental dis-
charge as buildings constructed during this period are demol-
ished (4) .
(4) Summary Characterizations of Selected Chemicals of Near-Term
Interest. EPA 560/4-76-004 (PB 255 817). U.S. Environmental
Protection Agency, Washington, D. C., April 1976. 50 pp.
10
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SECTION 4
ENVIRONMENTAL SIGNIFICANCE AND HEALTH EFFECTS
ENVIRONMENTAL SIGNIFICANCE
Emission Sources
Tracing various paths through which asbestos enters the environ-
ment is complicated by the fact that asbestos has approximately
3,000 uses (3). Asbestos enters the atmosphere from so many
sources that its presence may be regarded as ubiquitous, with
only a small portion of the fibers arising from natural sources.
Figure 1 presents a flowchart showing asbestos production, fab-
rication, consumption, and estimated disposal quantities in the
United States in 1972. From these estimates, it may be concluded
that mining and milling result in the majority of atmospheric
emissions, while asbestos fabrication in the construction indus-
try results in the major asbestos water emissions.
Corresponding to Figure 1, Table 6 shows the major industrial
sources of asbestos emissions. Also shown are the number of
plants for each product group and the respective surrounding
population density.
Table 7 shows estimated asbestos emission factors for mining and
milling, processing into products, and consumption of end-use
items.
Emission Levels
Significant quantities of asbestos fibers appear in rivers and
streams draining from areas where asbestos-rock outcroppings are
found. Asbestos fibers have been found in a number of drinking
water supplies, but corresponding health implications of ingest-
ing asbestos are not fully documented (4). Asbestos enters water
systems by airborne settling, dumping of waste effluent from
mining and milling operations, and dumping of asbestos-bearing
wastes. Recent evidence indicates that asbestos is leached from
asbestos-cement pipes in municipal water systems. In 1975,
asbestiform fibers were found in 10 widely separated potable
water supplies ranging in concentration from 0.25 x 103 fibers/m3
to 240 x 103 fibers/m. Long asbestos fibers have been found to
cause clogging of household appliances in some cities where
asbestos-cement pipe is leached heavily by the water (3).
11
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ACTIVITY AND AMOUNTS PROCESSED
PERMANENT USE = 535,352
17,127 64,891
TOTAL DISPOSAL
SOLID WASTE INCINERATED
SOLID WASTE TO LANDFILL
GRAND TOTALS
DISPOSAL
VIA
SOLID
WASTE
-
1,536
527
385
350
140
89
35
535
3,597
6,804
2,631
11,521
69,382
27, 779
443
6,963
53,115
178,638
DIRECT TO
AIR
597
1194
1791
153
53
38
210
14
16
7
54
547
54
129
37
220
WATER
48
48
246
42
4
21
2
4
1
5
325
28
28
LAND
53,288
5,045
58,333
-
-
182,235
16,400
165,835
2558
1196
3754
401
401
58, 333
15,204
165,835
239,372
Figure 1. Asbestos production, fabrication, consumption,
and disposal quantities in the U.S.
(metric tons/yr in 1972).
12
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TABLE 6. ASBESTOS PRODUCTS INDUSTRY AIR EMISSIONS
AND SURROUNDING POPULATIONS (3)
Total emissions, Number
Product group metric tons/yr of plants
Construction
Floor tile
Friction products
Paper and felt
Textiles
Gaskets, packing,
and insulation
Other uses
TOTALS
153
38
210
53
7
32
54
547
48
18
30
29
34
300
200
659
Surrounding
population
density,
people/km2
1,720
2,960
2,507
1,687
2,203
2,800
2,300
2,374 average
TABLE 7. ASBESTOS EMISSION FACTORS FOR VARIOUS SOURCES
Emission source
Emission factor,
kg/metric ton of
asbestos produced
Mining, total
Mining
Leading
Hauling
Unloading
Mining, total, 50% control
Milling
Milling, 50% control
Milling, 80% control
Processing:
Friction material, controlled
Asbestos-cement product, controlled
Textiles
Textiles, controlled
Asbestos paper
Asbestos paper, controlled
Floor tile
Floor tile, controlled
Consumptive uses:
Brake linings
Steel fireproofing, controlled
Insulating cement, controlled
Construction industry
5
2
1
1
1
3
50
40
10
3
0.5
20
1
2
0.5
2
0.5
5
5
13
13
13
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Exposure to asbestos fibers may occur throughout urban environ-
ments. Available data indicate that urban levels, averaging
29 ng/m3, are much greater than nonurban concentrations, which
generally appear to be less than 1 ng/m3 (3). Urban concentra-
tions are generated primarily from industrial sources or brake
lining residues, although other major sources include building
construction and demolition. Maximum atmospheric asbestos con-
centrations have been calculated using asbestos industry data.
These calculations indicate that a maximum asbestos concentration
of 6.2 x 10"9 g/m3 will extend 1 km from an average operating
asbestos plant (covering 2,060 km2), and will fall off inversely
with the square of further distances from the sources (3).
A recent study of street dust in Washington, B.C., showed
approximately 50,000 fibers/g, much of which appeared to have
come from brake linings (4).
HEALTH EFFECTS
The association of impaired human health with industrial exposure
to asbestos is well known. Hundreds of cases of asbestosis
(fibrosis of the lung) and pulmonary cancer associated with
mining and milling of asbestos and manufacturing of asbestos
products have been documented (5).
There is little evidence that low exposure to asbestos, such as
what is encountered in ambient air, produces asbestosis or pul-
monary carcinoma in human beings. These conditions have consis-
tently been reported only from heavy industrial contact with
asbestos. However, the discovery of association of a unique
tumor (mesiothelioma of the pleura of the peritoneum) with very
low exposure, or with casual contact with chrysotile asbestos
(usually after a long latency period), has raised a question
concerning human risk due to asbestos air pollution (5).
The following summary points have been listed for the epidemi-
ology of asbestos (5):
• All major types of asbestos can cause lung cancer, although
there are clear differences in risk with type of fiber and
nature of exposure. Since exposure and response to asbestos
are related, there is no excess risk when occupational
exposure has been low.
• All commercial types of asbestos except anthophyllite may
cause induction of mesothelioma. The risk is greatest with
(5) Scientific and Technical Data Base for Criteria and Hazardous
Pollutants-1975 ERC/RTP Review. EPA 600/1-76-023
(PB 253 942), U.S. Environmental Protection Agency, Research
Triangle Park, North Carolina, January 1976. 464 pp.
14
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crocidolite, less with amosite and apparently less with
chrysotile. With the last two, there seems to be a greater
risk in manufacturing than in milling.
There is evidence of an association of development of meso-
theliomas with air pollution near crocidolite mines and
factories using mixed fibers. There is no excess risk from
air pollution near chrysotile and amosite mines.
There is, at present, no evidence of any cancer risk to the
general public from asbestos in air, water, beverages, food
or in fluids used for administration of drugs.
Cigarette smoking enhances the risk of developing broncho-
genie cancer in workers exposed to asbestos. No association
between cigarette smoking and development of mesothelioma
has been demonstrated.
Pleural plaques (white patches on the lungs) are associated
with past exposure to all commercial types of asbestos
although not all pleural plaques are related to asbestos.
15
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SECTION 5
CONTROL TECHNOLOGY
Fabric filters (baghouses) have been found to be the most effec-
tive method for controlling asbestos emissions from manufacturing
processes (5). Typically, these baghouses use cotton fabric and
automatic shakers. The usual capacity is 140 m3/min to
570 m3/min with an air-to-cloth ratio of less than 0.91 m3/min-m2
of cloth (6). According to the U.S. Environmental Protection
Agency (EPA), baghouses can limit fiber concentrations (counting
fibers longer than 5 urn) to fewer than 0.5/cm3 of exhaust air
(equivalent to weight concentrations of less than 25,000 ng/m3).
This standard is at the lower limit of detection by the optical
microscope analytical method employed for asbestos measurements.
Therefore, the currently proposed limit of 2 fibers/cm3 appears
technically feasible for effluent air streams from asbestos
factories.
Although baghouses are the most successful control technology to
date, they are not without their disadvantages. The most impor-
tant disadvantages are: 1) relatively large installation area
required for gas flow, 2) greatly reduced efficiency for even
minor bag damage, 3) low cleaning efficiency after bag replace-
ment, 4) high cost of bag replacement, and 5) upper limits on
process temperature.
In asbestos mining, small fabric filters are used for control
during drilling. Cyclones, bag collectors, and properly designed
ducts are then used for dust control in the crushing operation.
Cyclones, sometimes followed by baghouses, are used as control
devices on dryers (6).
Asbestos milling involves crushing, separation from the dust by
air aspiration, and grading the fibers by cyclones connected to
the baghouses. Also connected to the baghouses are the screens,
separators, recirculating systems, regrading areas, pressure
packers, and other dust control systems, i.e., vacuum systems.
Generally, all conveyors are covered, and low velocity hoods are
used for control of dust in other areas (6).
(6) Harwood, C. F., P. Siebert, and T. P. Blaszak. Assessment
of Particle Control Technology for Enclosed Asbestos Sources.
EPA 650/2-74-008, U.S. Environmental Protection Agency,
Washington, D.C., October 1974. 135 pp.
16
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The most common method of controlling emissions in open areas and
waste piles is spraying with water or with aqueous and organic
solutions of wetting agents, oils, and polymers. Physical and
vegetative coverings are also used on waste piles. Water spray-
ing is most commonly used in demolition of buildings. Vacuum
systems and respirators are used in repair of pipes and boilers
within buildings and ships.
Waste control technology for removing asbestos fibers from wastes
is more involved and costly. Usually a combination of settling,
sand filtration, diatomaceous earth filtration, and chemical
coagulation is required, depending upon the amount of asbestos
present and the degree of removal required. Research has been
and is being conducted on coagulation and flocculation methods
using ferric chloride, ferric hydroxide, calcium hydroxide,
bentonite clay, and cationic polyelectrolyte.
Baghouses have been found to be the most effective method to con-
trol asbestos emissions from manufacturing processes and are
currently in use in some segments of the asbestos industry.
These devices can limit asbestos fiber concentrations (counting
fibers longer than 5 pm) to fewer than 0.5/cm3 of exhaust air
(equivalent to weight concentrations less than 25',000 ng/m3) (5).
The control efficiency for asbestos milling emissions has been
estimated to be 96%. Control efficiency, as well as control
costs, vary proportionally with plant size for the industry.
Considering only total costs of controlling asbestos emissions
from all asbestos plants (using 1970 dollars), industry control
costs equal $6,946,000 as shown in Table 8 (5). Assuming that
the service life for control equipment is 10 years and that
annual operational and maintenance costs, interest, insurance,
and taxes together amounted to 20% of the original investment,
the national annualized cost is calculated as $2,084,000/yr in
1970 dollars.
TABLE 8. ASBESTOS PRODUCTS INDUSTRY CONTROL COSTS
(1970 DOLLARS)
InvestmentsAnnualized costs
Product group ($1,000) ($1,000)
Construction
Floor tile
Friction products
Paper and felt
Textiles
Gaskets, packing, insulation
Other uses
Totals
2,400
216
720
348
1,700
1,169
393
6,946
720
64.8
216
104.4
510
350.8
117.8
2,083.8
17
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Monitoring of plant asbestos concentrations represents a signifi-
cant additional cost. In 1973, EPA estimated that the cost of
determining the asbestos content of sprayable insulation material
is in the range of $300/sample (using an electron microscope).
Air sampling and subsequent analysis would be even more expen-
sive. Based upon an instrument cost of $100,000 and a life of
10 years with 2 or 3 man-days per analysis, the cost of analyses
for air sampling would probably be in the range of $700/sample.
The national cost of surveying 659 plants once a year at this
rate would total about $460,000/yr. (To sample once a month,
the annual cost would be $5.5 million.) (5)
The national control and monitoring costs (one air sampling per
year), then, would add to slightly more than $2,600,000. A 10%
supplemental cost for enforcement would run the total national
bill to about $2.9 million/yr (5).
18
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SECTION 6
REGULATORY ACTION
An air standard has been promulgated for a number of major com-
mercial sources of asbestos fibers. Asbestos is listed as a
priority pollutant under the Federal Water Pollution Control Act
which, together with the National Pollutant Discharge Emission
System (NPDES) permit program, should reduce asbestos discharges.
EPA is sponsoring an extensive national asbestos monitoring pro-
gram; preliminary findings indicate that asbestos is a widespread
contaminant of drinking water. The National Academy of Sciences
(NAS) is reviewing the implications of these findings (4). Regu-
latory actions, control options, and attendant impacts concerning
asbestos include (7):
Drinking Water Standard - Asbestos is one of the contaminants
being considered in a study by the National Academy of Sciences
on the health effects of contaminants in drinking water as a
requirement of the Safe Drinking Water Act. The report deadline
was December 15, 1976. Edgar Jeffrey, WSD, (214) 749-2106.
Hazardous Air Pollutant Standard - Iron ore beneficiation plants
are being studied to determine the feasibility and desirability
of extending coverage of current Hazardous Air Pollutant Stand-
ards to this possible source of asbestos. Gilbert Wood, OAQPS,
(919) 688-8146 X-295.
Workplace Standard - A downward revision of the workplace expo-
sure limit has been proposed. After economic impact studies are
completed and public hearings have been held, the revised stand-
ard may be promulgated. William Warren, OSHA, (202) 523-7177.
Workplace Studies - The brake lining and clutch rebuilding indus-
tries are being studied to determine the best means for protect-
ing workers. This classification of workers is not presently
covered by workplace standards, and recommendations were to be
sent to OSHA before the end of the year. John Dement, NIOSH,
(513) 684-3191.
(7) Identification of Selected Federal Activities Directed to
Chemicals of Near-Term Concern. EPA 560/4-76-006
(PB 257 494), U.S. Environmental Protection Agency,
Washington, D.C., July 1976. 36 pp.
19
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Mine Safety Standard - The mine safety standards for metal and
nonmetal industries, including asbestos, had a revision deadline
of late 1976. H. P. Richardson, MESA, (202) 235-8307.
20
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REFERENCES
1. Kirk-Othmer Encyclopedia of Chemical Technology, Second
Edition, Vol. 2. John Wiley & Sons, Inc., New York, New
York, 1963. pp. 734-747.
2. Clifton, R. A. Asbestos. In: Minerals Yearbook, 1974;
Vol. 1: Metals, Minerals, and Fuels. U.S. Department of
the Interior, Washington, D.C., 1976. pp. 179-189.
3. Moll, K., S. Baum, E. Capener, F. Dresch, R. Wright,
G. Jones, C. Starry, and D. Starrett. Hazardous Wastes.
A Risk-Benefit Framework Applied to Cadmium and Asbestos
(PB 257 951). U.S. Environmental Protection Agency,
Washington, B.C., September 1975. 272 pp.
4. Summary Characterizations of Selected Chemicals of Near-Term
Interest. EPA 560/4-76-004 (PB 255 817). U.S. Environ-
mental Protection Agency, Washington, B.C., April 1976.
50 pp.
5. Scientific and Technical Data Base for Criteria and Hazardous
Pollutants-1975 ERC/RTP Review. EPA 600/1-76-023
(PB 253 942), U.S. Environmental Protection Agency, Research
Triangle Park, North Carolina, January 1976. 464 pp.
6. Harwood, C. F., P. Siebert, and T. P. Blaszak. Assessment
of Particle Control Technology for Enclosed Asbestos Sources.
EPA 650/2-74-008, U.S. Environmental Protection Agency,
Washington, D.C., October 1974. 135 pp.
7. Identification of Selected Federal Activities Directed to
Chemicals of Near-Term Concern. EPA 560/4-76-006
(PB 257 494), U.S. Environmental Protection Agency,
Washington, D.C., July 1976. 36 pp.
21
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing}
1. REPORT NO.
EPA-600/2-79-210C
2.
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Status Assessment of Toxic Chemicals: Asbestos
5. REPORT DATE
December 1979 issuing date
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
T.R. Blackwood, S.R. Archer
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Monsanto Research Corp
1515 Nichols Road
Dayton, Ohio
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
68-03-2550
12. SPONSORING AGENCY NAME AND ADDRESS
Industrial Environmental Research Lab* - Cinn, OH
Office of Research and Development
U.S. Environmental Protection Agency
Cinmnna.t.-i . Ohin
13. TYPE OF REPORT AND PERIOD COVERED
Task Final 11/77 - 12/77
14. SPONSORING AGENCY CODE
EPA/600/12
15. SUPPLEMENTARY NOTES
lERL-Ci project leader for this report is Dr. Charles Frank, 513-68U-W81.
16. ABSTRACT
This report outlines the mining, milling, uses, and health effects of
asbestos. Its major applications are in asbestos cement products, floor
tiles, electrical equipment, brake linings, and flame resistant compositions.
Impaired human health from industrial exposure to asbestos is well known.
Additional information is needed on the effects of low level asbestos
concentrations in air and water. Present control technologies, regulations,
and major sources of pollution are reported and areas where information is
needed are indicated.
17.
KEY WORDS AND DOCUMENT ANALYSIS
a.
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Asbestos, crocidolite, Amphiboles, Fibers,
Natural Fibers, Nonmetalliferous minerals,
Silicate minerals, Asbestos Deposits,
Serpentine, Mineral Deposits, Nonmetalli-
ferous Mineral Deposits, Asbestos Cement
Products, Concrete Products, Concrete
Pipes, Shingles, Asbestosis, Occupational
Diseases. Pneumonoloniosis. Pulmonary Fi-
Mining, Textiles,
Construction, Plastics,
Insulation, Friction
Products
68A
68D
68G
s. DISTRIBUTION STATEMENT brosis, Respiratory Dis
Release to Public
Y CLASS (This Report}
Unclassified
21. NO. OF PAGES
32
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (Rev. 4-77)
PREVIOUS EDITION IS OBSOLETE
22
U.S. GOVERNMENT PRINTING OFFICE: 1980-657-146/5509
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