Exposure Asssssoent for Asbestos
Contaminated Verniculite
Versa.tr Inc., Springfield, VA
PBS5-133C85
Prepared tor.
Protection Agency, Washington, DC
Feb 85
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UnirodStKw
Envvonmanal Ptt
Agency
Offcaof
Toxic SutxiancM
WWii.Tg-.Dn. D.C. 20460
EPA 56tVSflM13
PB85-183085
TcDoeSufciancw
Exposure Assessment for
Asbestos - Contaminated
Vermicullte
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K&QKT DOCUMENTATION ; >_««««T NO. t Z.
PMJ£ 1 EPA 560/S-S5-013 |
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Exposure Assessment for Asbestos-Contaminated Veraiculite
A*hor(*lGina H. Dixon, John Doria, J. Randall Freed, Patriria Wooo,
Ira.Mflv.^Thfinn«iQn_Cha»hp.ra-. Pwrns Desai
Versar Inc.
6850 Versar Center
Springfield, VA 22151
United States Environmental Protection Agency
Of f :ce of Toxic Substances
Exposure Evaluation Division
HashJ.rcton. D.C. 2046,1
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PB35 18 30 3 5 /'AS
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11. CaxrecUQ «r OnMtO Na.
(068-01-6271 and
m 6B-02-39fi8
Final Report
14.
SPA Proiecf. Officer. Michael A. Callahan: EPA Task Manrger, Lynn A. Delpire
tastna (Umic Z
This docunent is an exposure assessment for asbestos-ccr.tariinated vemiculite.
Such exposure is found to occur ,T,a'inly via irhalation: inoestion an^ rernai ansorotion
are insignificant routes of exoosure. Vemiculite is released to the air during
mining, milling, exfoliation, transport, and use. These operations nay also release sone
asbestos fibers, which are readily transporter! through the atrsosphere.
Ascestos, Air pollution sar.plirg, Industrial hygiene, Enviror.nental nonitoring,
E.-.vironner.tal exposure pathway, Particle resuspension, Xincral indusrrv,
Exposure, Ir.^oor air pollution.
Vemiculite, Inhalation exposure. Occupational exposure. Consumer exposure,
Ambient cxcos'-re
e. esavn r«4d/e«w 06 J, OP G, OP.I, )3 E.
19. S*eunty Citi fT»'
Unclassifieo
j 21 .HO- 0( ••(•*
I IIP
; 2tL Stcunty Cut (TMt P«f(>
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EPA 560/5-85-013
February 1985
Exposure Assessment for Asbestos-Contaminated VernlcuIHe
by
Glna H. D:xon, John Dorla, J. Randall Freed, Patricia Wood,
Ira May, Thompson Chambers, Purna Desal
EPA Contract No. 68-01-6271 an
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DISCLAIMER
This document has been reviewed and approved for publication t>y the
Office of Toxic Substances, Office of Pesticides and Toxic Substances.
U.S. Environmental Protection Agency. The use of trade names or
cooroerdal products does not constitute Agency endorsement or
recommendation for use.
iii
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FOREWORD
This document 1s an exposure assessment for asbestos-contaminated
verwlcullte, developed for the U.S. Environmental Protection Agency
(EPA), Office of Toxic Substances (OTS). It reviews the available
exposure data for asbestos In vermlcullte, and estimates asbestos
exposures to workers and consumers who come Into contact with
asbestos-contaminated vermlcullte.
OTS has long been concerned about human exposure to asbestos. OTS
became Interested In asbestos-contaminated vermlcullte as a result of Us
concern for exposure to asbestos.
Information for the exposure assessment was sought through a
literature search, discussions with U.S. Government regulatory agencies.
discussions with a consultant to the vermlculite Industry, and a limited
asbestos sampling and analysis study conducted for EPA at several sites
working 1n the vermlcullte Industry. Many information gaps exist 1n this
exposure assessment. As of Its writing, however, this report 1s believed
to represent the most up-to-date attempt at characterising human
exposures to asbestos 1n asbestos-contaminated vermlcullte.
Michael A. Calla^an, Chief
Exposure Assessment Branch
Exposure Evaluation Division (TS-798)
Office of Toxic Substances
Preceding page blank
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TABLE OF CONTENTS
Page No.
FOREWORD ................... v
TABLE OF CONTENTS ........... ........................ v^
LIST OF TABLES .............. ........................ «x
LIST OF FIGURES ...................... !.!!!!!!!!!!.'!!!!!!!!
1. EXECUTIVE SUMMARY
2. INTRODUCTION ......................................... 3
2.1 Background ...................... !!"!!!!!!!!!!!! 3
2.2 Scope of Work ................... ................ 4
3. GENERAL INFORMATION .................................. 5
3.1 Mineralogy of Vermlcullte ......... .............. 5
3.2 The Geology of Vermlcullte Occurrences .......... 6
3.3 Chemical and Physical Properties ................ 8
4. SOURCES .............................................. 13
4.1 Releases from Mining and Hilling ....... '.'.'.'.'.'.'.'.'. 13
4.2 Releases from Exfoliation ....................... 13
4.3 Releases During Transportation ........ .......... 16
4.4 Releases During Consumer use .................... 16
5. EXPOSURE PATHWAYS AND ENVIRONMENTAL FATE ............. 19
5.1 Transport and Fate .............................. 19
5.1.1 Transport Processes ...................... 20
5.1.2 Environmental Fate ....................... 28
5.2 Identification of Principal Pathways of Exposure. 32
5.2.1 Inhalation of Asbestos-contaminated
VermlcuHte .............................. 32
5.2.2 Ingestlon of Asbestos-contaminated
VermlcuHte .............................. 33
5.2.3 Dermal Absorption of Asbestos-contaminated
Vernlcullte .............................. 34
6. MONITORING DATA AND ESTIMATES OF ENVIRONMENTAL
CONCENTRATES ....................................... 35
6.1 Monitoring of Mining and Milling Facilities ..... 35
6.2 Monitoring of Exfoliation and Product
Formu'iatlon ................................. 40
6.3 Monitoring of Ambient Air Near Mines and .........
""I* ........................................... 40
6.4 Estimates of Environmental Concentrations of
Asbestos from VermlcuHte ....................... 50
6.4.1 Releases from Exfoliation Plants ......... 50
6.4.2 Releases from Use of Products
Containing VermlculUe ................... 56
Preceding page blank
vn
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TABLE OF CONTENTS (Continued)
Page No.
7. EXPOSED POPULATIONS 61
7.1 Occupational Populations 61
7.1.1 Miners and Millers 61
7.1.2 Exfollators 61
7.1.3 Other Qccupat'-oisally Exposed
Populations 66
7.2 Consumer Populations 77
7.2.1 Attic Insulation 77
7.2.2 Lawn and Garden Fertilizers 77
7.2.3 Houseplants 77
7.2.4 Other Minor Uses 78
7.3 Populations Exposed to Asbestos-contaminated
tfermlculHe 1n the Ambient Environment 78
8. INTEGRATED EXPOSURE ANALYSIS 31
B.I Exposure Profiles and Calculations 81
8.1.1 Occupational Exposure 8?
8.1.2 Consumer Exposure L2
8.1.3 Ambient Exposure 91
8.1.4 Other Exposure Scenarios 92
8.1.5 Integrated Worst-case Exposure Scenario ... 93
8.2 Uncertainty of Analysis 93
9. REFERENCES 97
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LIST OF TABLES
PageNo.
Table 1. Selected Properties of Exfoliated VermicuTite 9
Table 2. Physical Properties of Graded Vermiculite from
w.R. 6,-ace and Co.. Llbby, Montana K1ne 11
Table 3. Vertnlculite Releases from Mining and
Beneflciatlon of VerralculUe Arc 14
Table 4. VermlculHe Releases from Exfoliation of
Vermlculite 15
Table 5. Estimated Vermlcullte Releases While
Transporting 17
Table 6. End Uses of Exfoliated and Unexfollated
VermlculHe 18
Table 7. Indoor Reentralnment Potential 26
Table 8. Suramary of Optical Hicroscopy/XRD Analysis
Results 37
Table 9. Summary of Electron Microscopy Analysis 38
Table 10. Results of Phase-Contrast Analysis of Air
Samples Collected at Three Sites 41
Table 11. Summary of Monitoring Data for Asbestos-
containing Vermlcullte 43
Table 12. Asbestos 1n Bulk Samples From O.H. Scott and
Sons Co 49
Table 13. Data for Vernlculate Exfoliation Plant -
Estimated Atmospheric Concentrations 51
Table 14. Modeling Estimates of Ambient Asbestos Fiber
Concentrations Surrounding a Vermlcullte
Exfoliation Plant 53
Table 15. Location, Employment, and Products of U.S.
Exfoliation Plants 62
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LIST OF TABLES (Continued)
Page No.
Table 16. Estimates for Vermlcullte Transportation from
Exfoliation Plant .............................. 67
Table 17. Summary of Estimated Population Exposed to
Vermlcullte
Table 18. Sites of Exfoliation Plants and Populations
ExP°«J .......................................... 80
Table 19. Summary of Inhalation Exposure to Asbestos
1n Vermlcullte ................................... 83
Table 20. Occupational Subpopulatlons: Exposure
Potential ...................... . ................. go
Table 21. Worst-case Individual Exposure Level Profile ..... 94
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LIST OF FIGURES
Page No.
Figure 1. Isopleths of Total Numoer of Episode-
Days 1n 5 Years 21
Figure 2. Theoretical Settling Velocities of Fibers 23
Figure 3. Typical Values of Washout Coefficient 24
Figure 4. Variation of Zeta Potential with pH for
Amoslte Using the Streaming Potential and
Electrophoresls Techniques 30
Figure 5. Variation of Zeta Potential with pH for
CroddoHte Using the Streaming Potential
and Electrophoresls Techniques 30
Figure 6. ATM-SECPOP Annual Average Concentration Estimates
for Wind Rose Sectors of St. LouU, HO 54
Figure 7. Atmospheric Transport Model (ATM) Annual
Average Asbestos Concentrations 55
Figure 8. Estimated Asbestos Concentrations During
Installation of Loose-fill vermlculHe
Insulation 57
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1. EXECUTIVE SUMMARY
VerrolcuUte Is a micaceous hydrate of magnesium, Iron, aluminum, and
silica. It often coexists 1n nature with asbest 1 firm minerals, and the
asbestos may remain as a contaminant through processing to end use. The
major processing stop, exfoliation. Involves heating the mineral to drive
off part of the'nydratlon water; this produces small, lightweight,
lov-denslty pieces. Host vermlculHe products use the exfoliated mineral
and fall Into one of three categories: lightweight aggregates.
Insulation, and horticultural and agricultural products.
Exposure to vermlcullte contaminated wltn asbestos occurs via
Inhalation; 1ngest1on and dermal absorption are Insignificant route-; of
exposure. VermlculHe 1s released to the air du-1ng mining, milling,
exfoliation, transport, and use. These releases iilso Involve release of
asbestos fibers, which are readily transported tnrough the atmosphere.
Exposure to asbestos-contaminated vermlcullte 1s an occupational and
consumer concern, and occurs via ambient air near point sources.
Occupational asbestos exposure levels wy reach 1.9 f/cc In mining,
9.7 t/cc In bsnef1dat1on, and 0.38 f/cc '.n erfo'.latlon. These exposures
affect a relatively small population of about 2.4UO people. A much
larger numfier of persons may encounter asbestos during crads or
commercial use of vermlcullte products, but are expected to receive lower
exposure.
A large number of consumers use vermlcullte products that may be
contaminated with asbestos. Over 74 million persons use lawn and garden
fertilizers each year. If the fertilizer 1s vermlcullte-based. estimated
exposure levels of 4.4 vg/m3 and 28 ug/m3 could result from lawn
treatment and gardening, respectively. A time-weighted average exposure
level of 6800 ng/m3 asbestos 1s estimated for consumers Insulating
their attics with loose-fill vermlcullte: this could affect 1S8.00C
persons per year. These estimated consumer exposures are based or, the
worst-case assumption that vermlcullte contains 1 percent asbestos.
A large population 1s exposed to asbestos 1n ambient air near
vermlculUe point sources. Approximately 13 million persons are
estimated to live near exfo!1at1o.. plants, and the'.r asbestos exposure
level may n:acn 0.025 yg/m3. A smaller number of persons live near
mires and mills and receive an unknown asbestos exposure.
This exposure assessment represents the best possible estimate cf
exposure to asbestos from vermlcullte. Many of the scenarios are based
upon very broad assumptions since definitive data are lacking 1n many
areas.
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2. INTRODUCTION
2.1 Background
Vermlcullte 1s a micaceous mineral, a hydrate of magnesium, iron,
alumlnua, and silica. The raw ore, when heated, expands (exfoliates) to
form low-density pieces. Exfoliated vermlcullte 1s used primarily 1n
lightweight concrete aggregates (21.4 percent of total production), as an
aggregate and for fireproof Ing 1n construction premises (11.3 percent),
as loose-fill or block-fill Insulation (13.9 and 15.9 percent.
respectively), for horticultural uses (13.2 percent), and as a carrier
for agricultural chemicals (15.4 percent) (JRB 1982). Crude
(unexfollated) vermlcullte Is used 1n gypsum wallboard (6.7 percent) and
has numerous minor uses (JRB 1982).
Vermlcullte has been mined In the United States since 1929; four
mining sites are currently 1n operation. W.R. Grace and Company, the
largest domestic supplier and user of vermlcullte, acknowledged In 1971
the presence of asbestos contamination 1n the ore mined at their Ubby,
Montana facility. Even after the ore was processed to remove Impurities
(benefdelated), some amphlbole asbestos was detected 1n the verrslculHe
(USEPA 1960a).
The Llbby ore was used for some years by the O.M. Scott anc" Sons
Company In their manufacture of agricultural chemicals. In 1S7S. O.H.
Scott and Sons reported health problems experienced by employees Involved
1n vermicullte processing. Bloody pleural effusions had been detected 1n
4 of 350 workers; a follow-up study by the Occupational Safety and Health
Administration (OSHA) found 32 cases of pleural or Interstitial
abnornalIties. The nature of these Illnesses was similar to conditions
seen 1n Individuals with asbestos-related diseases (USEPA 1980a).
These findings led to a Priority Review Level 1 study (PRL-1),
performed by EPA's Assessment Division 1n 1980. The PRL-1 preliminary
exposure assessment Identified numerous dsta gaps that could be filled
only by an Intensive monitoring effort.
This monitoring effort was begun under the direction of the Exposure
Evaluation Division of EPA 1n late 1§SO. It was designed to determine
the degree and type of asbestos contamination found in vermlculUe from
various sources and ^n various states of processing. The scope of the
monitoring study was altered after a priority shift within EPA. Host of
the samples were taken from vermlcullte mining and milling operations.
with a few samples taken from vermlcullte exfoliation (HRI 1982).
Preceding page blank
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This exposure assessment addresses the data found In vernUulUe
Industry records, the 1nfor,,>at1on In the PRL-1. the monitoring data
Obtained by EPA. and other sources to provide an estimate of the extent
of exposure to asbestos from mining, processing, and use of
asbestos-contaminated vermtculHe. The assessment will provide
Information for any future estimation of risk and for subsequent
regulatory action.
2.2 Scope of Work
The objective of this task 1s to prepare a comprehensive assessment
or tne exposure of asbestos-contaminated veralcullte to humans through
occupational, consumer, and ambient-related pathways. The exposure
assessment covers Hve major components: sources, environmental pathways
and .ate, population studies, monitoring and modeling of environmental
concentrations, and Integrated exposure analysis.
Section 3, General Information, explains the geology, mineralogy, and
Physical and chemical properties of vermlcullte. Section 4 Is a summary
of sources of asbestos-contaminated vermicuiHe; 1t 1s based upon a
materials balance (JRB 1982). Environmental pathways and environmental
fate are addressed 1n Section 5. Section 6. Monitoring and Modeling
ion^$SeS da^3 from an OSHA survey and fron EPA-sponsored monitoring (HRI
ISB.
In the absence of data, many assumptions were made In estimating
releases, levels of exposure, and exposed populations. Host assumptions
were designed to provide estimates of exposure In plausible worst-case
scenarios, and all such assumptions are fully explained 1n the text of
this report. It should be noted that no effort has been made to estimate
the proportion of asbestos-contaminated verralcullte to which people are
exposed. Monitoring data (Chatfleld and Lewis 1979) Indicate that not
all vermlcullte 1s contaminated with asbestos; however, the exposure
calculations and population estimates of numbers assume that all
vermicullte mined and used In the United States 1s contaminated with
asbestos.
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3. GENERAL INFORMATION
The following sections present background Information on the
5U?« °ly,' §60log1ca1 occurrence, and properties of venricullte.
S™ ?Jml * J?1*",*!6 m1nera1°9^al characteristics of Importance to
ISS?« ! IK' Secr?" 3'2 d1scusses th* seology of vermlculHe. and
XSl!l < %<°ex^eKC? °f Verni1cul1te and asbestos minerals In ore
oodles. Section 3.3 briefly summarizes the physical and chemical
Kra"l vern1cu1Ue- w1th emphasis on the beneflclated. exfoliated
3.1 Mineralogy of Verm1cum<»
te
o
the early 20th century. 1t wis not until
Unrr» rep°[t °f Vern"cu11te was made In 1824 for a deposit near
Worcester, Massachusetts (Bureau- of Mines 1980). Although some small
USe occurred ^n the early 20th centur. 1t wis not un
, .
t 7«iI r rn*4erra1eume ^ndustry was Barred with the opening of
the Zonal 1te Corporation mine near Ubby. Montana (Bureau of Mines 1980).
1? U"!qU! .a(W)ng m1nera1s 1n ^s ability to exfoliate when
Exf°11at1on 1s the separation of successive sheets or laminae
r VC "c^dL'rlR9 weathering or other physlcochemlcal processes
(Hyers I960), in Us natural state, vermlcullte has a perfect basal
cleavage and s easily spin into laminae. It 1s a soft mineral
S^J?6" " !rom 1'5 to 2 or more), has a feel like talc, and 1s
sometimes soapy when wetted (Myers 1960). Exfoliation from heating
results n expansion at right angles to the cleavage planes, and Is
accompanied by an Increase 1n volume of 800 to 1,200 percent (Myers
IrS L yer!"^u11te can also be exfoliated by chemical processes, such as
soaking 1n hydrogen peroxide, weak adds, and ot'.er electrolytes (Deer,
Howie, and Zussman 1962).
The vermlculUe crystal Is composed of two silicate lavers connected
by a hydrous layer. The thickness of the unit cell in fully hydrated
; JI5* Vb°U! U Ar9Stroms (Grjner 1«<>- Thermal analysis has
rl J l<* * Associated with vermlcullte Is released In three
fmh«rnH * TIfture ra"98S: the water thus ^leased is designated
unbound water.' "bound water," and "hydroxyl water- (Myers 1960).
onjnnratf 1S:«leascd at temperatures up to 300«F and Is apparently
in equll orlumwlth environmental water (I.e.. vapor or around water)
because Its release Is reversible. Unbound water can be'removed without
£tir°!r!!e!tedrSJal|; "^"^ t0 exf°11ate' ^ the amount of unSound
?t JI,r«[!""I ! I"1 the degree °f «fo"at1on. Sound water, which
Jn n! \l I ?mpratures ^ to SOC'F. 1s the water that must be removed
to permit exfoliation. Hydroxyl water 1s released at about 1.600'F It
rM!?I«rr°^ Si C0™erc1al exfoliation processes because Us remoCal
c^lrr, i '"tegratlon of the vernlcullte Into particles too small for
commercial use (Kresten and Berggren 1978).
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3.2 The Geology of Vermlcullte Occurrences
Macroscopic and microscopic types of vermlcullte deposits differ 1n
some basic aspects. Macroscopic versnlculltes are trloctahedral and have
a relatively narrow range of cation exchange capacity. Microscopic or
clay vermicuHtes may be either trloctahedral or dluctahedral and are
ciuch more variable 1n composition an* cation exchange capacity, making
rhem difficult 1n many Instances to distinguish frca montmorlHonlte
(Bassett 1959). The non-m1nable microscopic venBiculHe-clay minerals
are not discussed 1n this report.
Macroscopic vermlcullte occurs 1n four types of host rocks: (1)
ultramaflc and mafic, (2) gneiss and schist, (3) carbonate rocks, and (4)
ganlte rocks (Deer, Howie, and Zussman 1962; Petrov 1962). Each of these
has characteristic features. All of the major commercial deposits belong
to the first category, and the material that Is mined Is mixed-layer
verm1cu11te-b1ot1te or vermlcullte-phlogoplte (Petrov 1962). In the
gneiss-schist type, the vermlculUe occurs as layers In banded
inetamorj.Mc sequences. In the third category, veralcullte flakes close
to the magnesium and member are sometimes found distributed through
marbles ranging from calclte to magneslte composition. The
fourthcategory refers to blotlt? 1n granite rocks that has weathered to
an expanded or partially expanded alteration product of blotlte and that
puffs when hected *n a flame (Petrov 1962).
A perennial problem 1n the study of macroscopic vermlcullte Is the
question of hydrothermal versus supergene origin (Sassett 1959; Boettcher
1966). This problem Is relevant to the question of asbestos
contamination and the question of fibrous vermlcullte formation. It
would appear that commercial deposits, at least, are of supergene
origin. A hydrothermal origin of vermlcullte would provide temperatures
and pressures too high to allow for the survival of the asbestlform
minerals; also, formation of fibrous vermlcullte would not be possible.
Therefore, only deposits formed supergenlcally could contain fibers or
asbestlform minerals. The petrologlcal relationships for the deposits of
Interest suggest that pyroxenes, amphlbole-, (both asbestlform and
nonasbestlformj and oUvlnes In ultramaflc rocks (ioih Igneous and
mttamorphlc) were first altered by solution and volatilization from
Intrusive syenites, carbonatltes, and pegmatites to form blotite,
phlogoplte. perpentlne (both chrysot'He and the non-fibrous varieties),
ard chlorite (Bassett 1959, Hunter 1950). VermlculUe was subsequently
formed by the action of ground water on supergenes which leached out
alkalis, redistributed magnesium, and added Interlaver water fnolecules
(Bureau of Mines I960).
The most common parent mineral In vermlcullte deposits 1s blotlte.
Other minerals commonly present Include quartz, felcspar, apatite,
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*is >"•"* —*•»*«s&'ystxss (6urHU
,
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were seen and where the plates are strained. This was seen In the
basement of a deposit In Malawi and 1s probably the result of mild
hydrothermal conditions after the genesis of the vermlcullte. What was
observed was a topotatlc alteration of the verrakullte plate Itself. The
alterations occurred 1n three steps, according to Klfsud et al. (1577):
(1) surface cracks developed along well-defined crystallographtc
directions (S1-0-S1 chains); (2) the vermlcullte folded back at the edges
of the rocks; and (3) the looter vermlcullte ribbons were transformed to
crysotlle, undergoing chemical changes mainly by a removal of Fe and an
enrichment An Kg and OH.
Thus, vermkulUe and asbestos can coexist 1n separate veins or be
Interlayereo 1n the same vein. Only the study of each mineral deposit
could shed light on how the commercial vermlcullte and asbestos coexist.
Such a study would provide Insight Into the question of whether the
asbestos can be separated and, 1f so, whetner 1t can be separated more
easily before exfoliation.
3.3 Chemical ano Physical Properties
Vermlcullte varies 1n chemical composition; a useful formula for
vermlcullte 1s:
.7 - 1.0 «93.5 - 5.0 (F«*. A')2.5 - 1.0
^2.0 - 3.5, S16 . 5.5) 02C (OH>4 (^0)7 _ 9
Crude vermlculUe has a loose bulk density or 640 to 1000 kg/m3;
exfoliated vermlcullte expands to a bulk density of 56 to 192 kg/m3
(JRB 1982). This low density 1s Important ti Its uses as an aggregate In
concretes and plasters and in some Insulation and packing applications.
Another Important characteristic of vermlcullte Is Its significant
capacity for reversible cation exchange. Many cations can be
substituted, principally for tne magnesium and calcium (Deer, Howie, and
Zussman 1962). This permits use of verrokullte as a fertilizer and soil
additive. The cation exchange capacities, expressed a mini-equivalents
per 100 grains of vermJcullte, range from 35 to 70 for unexfollated ore
and from 20 to 60 for exfoliated vermlcullte (JRB 1S82).
Vermlcullte has a very low thermal conductivity. This property
permits wide usage of vermlcLillte as a heat-resistant Insulator 1n
steelwork and castable refractories. Selected properties of expanded
vermlcullte are listed 1n Table 1.
Benefldated vermlcullte 1s available In a wide :1ze range. K.R.
Grace separates 1t Into five sUe grades; Grade 1 Is the largest and
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Table 1. Selected Properties of Exfoliated Vermiculite
Property
Value
Thermal conductivity (Btu in hr"1 ft"2 025
Specific heat at O'F (cal g -1 ^r1) 0.20
Specific heat at 3CX)*F (cal g'1 '^~i) 0.24
%>ecific heat capacity (J kg"1 "^t"1) 840
Specific gravity 2>6
Pusicn point CO 1.200'*- 1,300'
Melting point Cc) 1<315.
Sintering tenperature Cc) 1,260«
Cation exchange capacity (milliequiv/100 g)
Vermiculite ore (s. Carolina) 70
termiculite ore (Mantana) 35
Expanded vermiculite (S. Carolina) 20-60
Expanded vermiculite (t-isntana) 20 - 30
Source: JRB 1982.
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Grade 5 1s the smallest. Although company specifications were not
obtained, measurements of graded samples obtained 1n a monitoring effort
(MRI 1982) are presented in Table 2.
10
-------
Table 2. Physical Properties of Graded Vermlcullte from W.R. Grace
and Company, Llbby, Montana Mine
Grade
no.
1
2
3
4
5
Approximate
naxitum
dimension
(Jim)
5-10
3-5
1-3
0.3 - 1
0.2 - 0.5
Approximate
nurber of
partieles/g
23
130
1.700
11,000
130.000
Approximate
veight/
average
particle
42 mg
7.4 mg
0.58 mg
91 ug
7.6 ug
Source: MRI 1982
11
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4. SOURCES
The following section presents a summary of the Level I! vtralcallte
Tooot ta^nee performed for EPA's Exposure Evaluation Division (JRB
138,?). The materials balance estimates the amount of vermlculHe
processed and released during every step of production. JRB's release
data have been tabulated Into four charts, each expressing a najor step
in production: raining and milling, exfoliation, transportation, and
consumer uses. Little detail 1s presented 1n this section of the
exposure assessment. Further data are available 1n the siaterlals balance
report.
4<1 Releases from Hlnlno and Hilling (JRB 19821
Table 3 shows the verra'cullte releases during raining and
Denef1c1at1on of the vermlcullte ore. Beneflclatlon reraoves the
vermkullte from the gangue (waste or Impurities). In Table 3. the
amount referred to Is the amount of ore. which Includes the gangue.
- Ther9 are four V*"n1cul1te mines In the U.S. One million tons (1.2 x
10° kkg) of vermlcullte ore were rained and beneflclated 1n 1979 to
produce 314,000 kkg of crude vermlcullte. JR8 estimated that 802 kkg
were released to the air. 89,300 kkg were released to water, and 2.490
Kkg were released as solid waste (see Table 3). The water releases were
disposed of in settling ponds, and the water was recycled. The air
releases -vere fugitive releases from the dust control equipment. The
solid wastes were the participates collected 1n the dust control system
and were landMlled.
Three different techniques are used to mine and benefldate the ore.
No data were available for the Virginia Vermlcullte mine, so for Table 3
U was assumed that Virginia uses the same techniques as W.R. Grace 1n
tnoree. South Carolina. Tne largest releases from mining and
Denef1dat1or, are water releases from wet processes. The particular
steps associated with the greatest releases are concentration and
secondary screening, since these procedures remove raost 3f the gangue.
(Note that Patterson Vermlcullte does not use wet processes.) Any step
with a large air release 1s assumed to have dust control equipment.
4•2 Releas&s from Exfoliation (JRB 198?)
Ninety-four percent of crude vermlcullte 1s exfoliated. Table 4
Identifies oil the releases during exfoliation. Note that some crude
vermlcullte 1s Imported from South Africa. The exfoliation processes
used are the same, but since the Incoming feeds contain different amounts
of vermlcullte. they have different release rates. Ninety percent of the
releases are expelled In the exfoliation step.
Preceding page blank
-------
T«bl» ). Vornlcum*R*laa>«i I rat Mining and hMfleUtloA of VsrulcullU Or*
V.ll.
Procoii*
W.ilng
Overburden rwuval
frooXlng a loaJIng ore
Kiullng ore
Convoking
Oimplng & stockpiling
Prlivry tcroonlng
IVIiMiiy scroonlng
Cru^h Ing
Convoying
Secondary screening
Conveyino/bleiKjIini
Locundiry screening
ConcaiUraFlon
Wet flotation
Ocwitcrcd/ drying*1
Siiing/iloray?
Convuylng
Load ( ng
lloul Ing
Dulling
Screen Iny/sl/ Ing
TOfALS
Oraco, llbby. Kjntana
Amount*1 Alrc M«l«rc
(kkg) (kkg) (kkgl
748,000
2% 6
6.F3
70.2
i.ia
5.J9
748,000
108.
6.31
1.17
110,000
1.17
55.9 9.3)0
522,000
120. 23,800
2J.2
181.000
4.69
28.6
n.t
1.76
181, OOO 443.00 33.200
Virginia Vor.lcullto, Loo In,
Solid1 Procait* Aiwunt
(kkg) (kkg>
Hnl/ifl 439.OOO
Ovortwr Jan r«oval
flrnaklng £ loading
llaullng
Ounplng l«tod>plllng
Prlmsry washing 4J9. 000
-------
Table 4. V«rmlcuMt« Releases From Ixfo)tat1on of V«ri»Uul>te
W.R. Grace, Virginia and South Africa vtralcullta rtleatci
ExfoUatlon Process
ConvKvinq
Screening/siring
Corn 'ay ing
Exfoliation
Convoy itvj
Dcatoniixj
OiicjyUxj
Dulk loading
P remixes
Dust control
•mialii
Anovnt of
vermiaillte
(kk]
(Meg)
4.51
35.57
0.5b
4.2J3.G
4.37
396.2
77,42
j,7j.2.2
Patterson vcrnUutltt releases
Airount of
vertni oolite
(kky)
1,970
1,800
1,170
Air
(kkg)
52.4
0.138
0.69
1,61
Jij.j)
Hater
(kkg)
107 •
Ut«a»)
107^
Solid
(kkg)
77.0
26.2
1.07
1Q4.1
Souroe: JRD 1982.
-------
JRB assumed that every step had dust control equipment that was 98
percent efficient. It is estlnated that 4,500 kkg of asbestos collected
1n the dust control equipment, while 4,500 kkg are released as steam
either directly to the air or Into the dust collector. Three thousand
tons (3,027 kkg) were released as fugitive releases to the air. The
exfoliated product 1s transported to manufacturer 1n bags or bulk loads,
or as an Ingredient In prefixes.
4.3 Releases During Transportation (3BB 198?)
Table 5 shows transportation releases. Domestic crude vermlcullte 1s
transported from the mill to the exfoliation plant by railroad or truck.
Imported and exported vermlcullte are transported by ship and rail.
Exfoliated vermlcullte destined for consumer use Is transported 1n bags
or bulk loads. The estimated transportation releases are negligible.
Thlrty-;i1r.i kkg are released to the atmosphere, and 125 kkg are released
to the land due to spillage.
4.4 Releases During Consumer Use (JR6 1982)
Exfoliated vermlcullte 1s used In three major types of consumer
products. It Is used 1n place of sand as a lightweight Insulating
material In concrete; 1t 1s used as loose-fill and block-fill
Insulation; and 1t 1s used agriculturally as a growing medium or a
pesticide carrier. Unexfollated vermlcullte 1s used to make gypsum board
(drywall). The largest release from these uses 1s the sol'd release to
the lard. As a component of agricultural products, vernlcullte 1s
applied to the soil directly; 1t Is released to land from other products
as the result of spillage. JflB estimates that releases of vermlcullte are
Insignificant after Installation of the end-use product.
Table 6 summarizes releases from consumer use of vermlcullte
products. These release data spply equally well to commercial and
Industrial use of the products.
16
-------
Table 5. Estijnated Vermiculito Releases While Transporting
Ci-ude vormiculite
Amount transported
Otkg/yr)
Vermiculite releases
Solid ~
(kkg/yr)
Inpo rted
Exported
Total
302,000
27,200
31,700
10.8
15.1
0.15
25.9
Exfoliated vermiculite
in
in
t\t
Totals
132,000
C,220
6»,300
6.22
G.f.O
38.8
125.0
125.0
JV.n 1
-------
Table 6. End Uaoa of Exfoliated and Ur*>xfoliatod Varmiculita
Exfoliated use
Aggregates
Concrete
Plaster
Prunix
if as illation
Loose fill
Block fill
Packing
Agricultural
Growing ncdia
Carrier for agri-
cultural diunlcolu
Other
Tbtala
Unoxfoliated use
Cypsttn board
TV*.,,
Percent of total production0
36.2
23.0
1.02
12.2
31.2
14.9
16.2
0.07
30.7
14.2
16.5
1.71
99. j^
100.00
Quantity6 (kkq)
Ttotal
83,300
52,900
2,350
26,100
71,800
34.300
37,jQO:
151
70,600
32,700
38,000
3,930
SSiSSS,
19,400
249,400
Vermiculite
74.900
47.600
2,110
25,300
64,600
30,800
33,500
63,500
29,400
34,;: oo
3,540
207,000
14,700
221,700
Gangua
8,470
5,380
239
2,850
7,300
3,490
3,790
16
7,180
3,320
3,860
400
23,400
4,700
28t100
VRrmiculite releases (kkq)
Air
14.0
153.8
31.6
33.5
0.072J
33.8
0.24
3.54
271.4
11.1
282.5
Water
0.462
0.11
0.011
Jii6
0.6
Solid
445.1
242.2
4,025.2
345.1
144.5
29,400*
00.1
499
22x221.
922.
36,070.
ju iJuiivLtl Ixxti iLilu in Uuroou of Mines 19HO (JUB).
'^Quantity = (total product) x (percent).
*Nuiiibers do not add due to rounding.
Source: .)[«! 1982.
-------
5. EXPOSURE PATHWAYS AND ENVIRONMENTAL FATE
The roost important factor dictating the chemical fate of both
vermlcullte and asbestos (and, therefore, asbestos-contaminated
vernlculHe) 1s the chemical Inertness of both minerals. Neither
substance would be expected to undergo chemical transformation when
released Into the environment. Furthermore, their refractory nature
precludes the effect of melting/boiling point, solubility, vapor pressure,
octanol/water partition coefficient, etc. on their transport. Other than
density, the only physlcochemlcal property that Is of Importance 1n
assessing the atmospheric fate of asbestos-contaminated vermlcullte 1s
particle size and shape (USEPA 1930a).
Terrestrial and fluvial transport processes affecting vermlcullte are
not well characterized. The following section summarizes what 1s known
about the fate and transport of asbestos.
5.1 Transport and Fate
VeriRlcullte occurs naturally 1n many regions of the country, and can
be released directly to the environment by all normal geological
weathering processes. Rates of natural release can be altered by human
activity such as road building, mining, and construction.
The asbestos fibers from vermlcullte may enter the environment through
such human activities as (1) mining and milling, (2) transportlon,
(3) manufacture and use of products containing ver.n1cul1te, (4) demolition
of buildings 1n which vermlculHe 1s a structural component, and (5) solid
waste disposal of verm1cu!1te-conta1n1ng materials and mining and milling
wastes. Asbestos fibers are not bound chemically to the vermlcullte;
rather, the minerals coexist In the same matrix which, when chemically or
physically disturbed, may release the minerals.
Mining, milling, and exfoliation of vemficullte almost certainly
account for the vast majority of the environmental release of asbestos
from vermlcullte. Virtually all of the mined deposits are 1n rugged
country removed from heavily populated areas. Vermlcullte 1s transported
through the country 1n Us unexfollated state along all major routes of
transportation. Atmospheric asbestos dust -.ettles or 1s washed out by
precipitation; It then returns to the soil and to waterways. Asbestos
fibers are easily reiuspenderi by wind and water and an be redistributed
widely. Because of Its stability, asbestos must be regarded as persistent
1n the environment with an ultimate sink 1n soils or sedlirents.
The following sections deal with all the processes dffectlng the
environmental distribution of asbestos fibers. The actual vermlcullte
minerals are not addressed 1n this exposure assessment. The chemical fate
19
-------
processes affecting verinlcullte may be similar to those affecting
asbestos. Physical transport probably differs, however, since vermlcullte
particles entering the environment are probably larger than asbestos
particles, and particle size 1s a major factor affecting transport.
5.1.1 Transport Processes
(1) Atmospheric Transport
(a) Turbulence and Diffusion. Asbestos fibers are restricted
to the troposphere (I.e., the first 5 to 10 miles of the atmosphere).
above which lies the relatively stable, nonconvectlve stratosphere. The
vertical diffusion of fibers from a source may also be restricted by
surface Inversions or by an Inversion layer lying above an unstable mixing
A surface Inversion usually occurs 1n the early morning when light
cloud and wind conditions prevail. As the earth's surface 1s being
heated, convectlve currents ard turbulence Increase near the surface. If
the upper part of the original Inversion layer persists, atmospheric
diffusion 1s largely restricted to a mixing layer below the Inversion
layer (Hanta and lowry 1976, Hewson 1976). Such nixing heights nay range
from essentially zero at night to several kilometers In the afternoon;
typical seasonal means are 300 to 800 meters 1n the morning and 600 to
4.000 meters In the afternoon, depending on location (NcCormick and
Holzwortb 1976) .
Low mixing heights, low wind speeds, and the absence of precipitation
suppress dispersion and Usd to raised pollution levels; the persistence
of all three conditions 1s associated with air pollution episodes. Figure
1 gwes some Indication of the frequency of such episodes. Air pollution
episodes can be particularly acute in Industrialized valleys where
Inversions are a dominant meteorological phenomenon.
Both turbulent diffusion and w^nd disperse asbestos from Its point of
emission. Tnsse processes mix released fibers with ever-Increasing
volumes of air, lowering concentrations In the region of release and
dramatically reducing concentrations In areas peripheral to the asbestos
source. Three scales of turbulence can be defined (Whelpdale and
Hunn 1976):
• Hlcroscale: Small fluctuations responsible for the Initial
diffusion of asbestos 1n the first hour or EO of Its release.
• Mesoscale: Eddies with dimensions of several kilometers. This
turbulence can be consistent, as 1n the case of a sea breeze or
valley flow.
-------
Figure t. Isopleths of total number of episode-days 1n 5 years
with mixing helohts < 1500 m, wind speed < 4 m/sec,
and no significant pFedpltatlon - for episodes lasting
at least 2 days. Season with greatest number of episode-days
Indicated as winter (W), spring (SP), summer (SU), or autumn
(A)
Source: KcCorraick and Holzworth (1976).
21
-------
• Macroscale: Eddies of dimensions exceeding 500 km.
All three scales of turbulence can affect dispersion.
(b) Dry Removal Processes. Gravitational settling rates have
been determined experimentally for asbestos fibers 1n the absence of
turbulence; these rates depend principally upon fiber diameter and are
relatively Independent of fiber length (Timbrel! 1965). The same
conclusion was reached by modeling fiber aerodynamics (Sawyer and
Spooner 1978). The theoretical settling velocities are given In
F'.gure 2. Typical fibers reportedly have diameters less than 1.5 \im
(Dement and Harris 1979. Smith et al. 1973); single fibrils have diameters
near 0.06 \an. From Figure 2, fibers 1.6 vm In diameter would
theoretically fall three meters 1n about on? hour while single fibrils
would require over 15 days.
In the atmosphere, settling velocities for most asbestos fibers will
be negligible 1n comparison with turbulent vertical velocities. This Is
true for fibers with equivalent sphere diameters of less than 20 um*
(Wanta and Lowry 1976), I.e., fibers with diameters up to 6.4 um.
Larger fibers and fiber clumps would be subject to gravitational
settling. Inside buildings, turbulence generated by movement or air
through flow prolongs particle settling.
Fibers undergoing turbulent motion may collide with and adhere to
surface cover. The extent of fiber removal by Impactlon will depend on
fiber size and velocity, the rate at which the fiber 1s supplied to the
surface, and the degree to which various surfaces retain Impacting fiber
(Whelpdale and Munn 1976). This 1s a complex process for which no
quantitative removal estimates exist for asbestos.
(c> Precipitation. Pollutants are removed from the air during
rainfall at a rate proportional to their concentration {Wanta and
Lowry 1976). Denoting the concentration at time t as C(t) and the
Initially observed concentration as C0i
C(t) = C0e-vrt
where w, termed the washout coefficient. Is a function of particle size
and rainfall rate. Typical values of w are given In Figure 3. Evidently,
a rainfall rate of 0.15 1n/hr (3.8 nm/hr) reduces the concentration of
spherical particles 4 vm In diameter by 50 percent 1n two hours. Larger
particles are removed more efficiently, and this removal mechanism has
•The equivalent sphere diameter 1s defined as the diameter of a
sphere 1 gm/cm3 In density having the same fall velocity as the fiber of
Interest, A 20 ym diameter sphere so defined falls at a rate of 1.2
cm/sec 1n the absence of turbulence.
22
-------
I I I i i ill j^ T r;
10*
» IO~* f «m~< M».
mew AXIS
FI8CII AXIS HOftlZOMTAL
100 300
FI8CB LEMOTH.^«
Figure 2. Theoretical Settling Velocities of Fibers
Source: Sawyer and Spooner (1978).
23
-------
— M -
0.05
0.10
0.15
5 mm/nour
m /l>our
Mgure 3. Typical Values of Washout Coefficient
Source: Wanta and Lowry (1976).
-------
been found Ineffective for spherical particles of diameter less than
2 \>K (Haagen-SmK and Wayne 1976).
Results of a field monitoring effort for asbestos fibers seen to
confirm this effect for asbestos fibers (Harwood and Blaszak 1974). After
a week of precipitation, the concentration of fibers longer than 1.5 v">
was significantly suppressed, while levels for fibers of length less than
1.5 vm appeared unaffected. Removal rates for nonspheMcal particles
are unknown.
Reentralnment. Asbestos fibers may be reentralned by surface
winds, vehicular traffic, or Indoor movement. Indoor levels have been
compared during periods of no activity and high activity (Sebastlen et
al. 1979); the levels differed by one to two orders of magnitude for each
of three different rooms (Table 7).
Reentralnment of asbestos 1n environmental situations ha*, not been
studied directly except 1n the case of waste pile emissions. Nonetheless,
field measurements 1n conjunction with these studies suggest that 1t raay
be an Important secondary source, contributing significantly to ambient
levels 1n sooe Instance-.
Emissions froa waste piles are recognized as potentially Important.
During periods of high winds, asbestos has been observed at a playgrourid
and 1n houses near one Gump (USEPA 1974). Atmospheric asbestos emissions
from Industrial dumps and mine tailing piles were Investigated by Harwood
and Blaszak (1974) and by Harwood and Ase (1977). Dumps were determined
to be a significant and possibly hazardeu; source of asbestos fiber; the
reentralnment of unbound asbestos fibers proved to be responsible fo"* most
of ttie emissions. Partlculate emissions from tailing piles have been
estimated under various climatic conditions by PEDCO (1973).
In suramary, reentralniBt-nt of asbestos fibers does occur, and studies
of waste pile emissions Indicate trat H Is an Important secondary
source. Quantification of the effects of asbestos reentralnment has not
been alternated except at waste piles. Reentralnment 1s responsible for
the majority of asbestos emissions from waste piles and may also be
particularly Important 1n urban areas.
(e) Atnospherlc Asbestos Burden from the Use of Vermlcullte.
Evaluation of changes In the atmospheric burden of asbestos from the use
cf vernvlcul'.te Is Inhibited by four factors:
1. A comprehensive Inventory of asbestos emissions from vermlculUe
(as well as other sources) does not presently exist; only
exfoliation plants as point sources have been well studied.
25
-------
Table 7. indoor Reentrainroent Potential
toon without . itoon with
himan activity human activity
(ng/nr1) (ng/m3)
15 750
3 630
1 62
Source: Sebastien et al. (1979),
26
-------
2. The quantitative effects of asbestos removal mechanisms are
presently unknown.
3. The contribution of asbestos reentralnment to the atmospheric
burden has yet to be established.
4. Monitoring of asbestos 1n the environment cannot differentiate
between the different sources of asbestos contamination.
In general, atmospheric asbestos from contaminated vermlcullte can
come from a series of sources.
Industrial sources, such as stack emissions from exfoliation plants
and Industrial users of vermlcullte. probably contribute the bulk of
asbsstos from vernlculHe. Waste pile emissions may be another source.
Mining emissions, such as the dust produced from the strlp-mlnlny of
verralcullte deposits, cause localized asbestos contamination of air.
Workplace and other Indoor sources may Increase atmospheric asbestos
levels.
Although these sources have been studied to some degree 1n past
asbestos studies, ft 1s still Impossible to predict with any accuracy the
atmospheric concentrations of asbestos from contaminated vermlcullte.
(2) Fluvial Transport. Tailings from taconlte mining dumped Into
Lake Superior by the Reserve Mining Company at Silver Bay, Minnesota, have
provided the only opportunity to study the transport of asbestos 1n the
aquatic environment. These tailings contained more than 50 percent quartz
and about 40 percent cumralngtonlte-grunerlte (mean chemical composition
(Fe5Mg2S16022). Tailings were dumped Into the lake at the rate of
about 60,000 to 70,000 kkg per day: the water slurry containing the
tailings was released at a rate of about 2.4 x 10& m3/oay (cook
1973). As a result, asbestos has been detected 1n the drinking water of
Ouluth. Minnesota, about 75 miles distant (Cook 1975).
It has been shown that although the asbestos fibers are traveling
great distances 1n the water column, they are being coagulated and
sedlmented In the western part of the lake near the tailing delta (Kramer
1976). If this process were not going on, according to the calculations
of Kramer. 3.5 x 106 fibers/liter should be found distributed evenly
throughout the volume of Lake Superior. In actuality, however, only 1 x
10& fibers/liter are present 1n the eastern part of Lake Superior.
Kramer found, as well, that the greater the distance frorc the tailings
themselves, the richer in magnesium the asbestos became. This effect was
attributed to the magnesium-rich asbestos having a more sensitive zeta
potential which would prevent coagulation and sedimentation.
27
-------
ronnu ILI P!?!K asbestos might settle under certain environmental
conditions. Although no specific data are available on settilna rates of
asbestos, several analytic models of the physical rocesses n
yc moes of the physical processes naatc
- <
-. ,
a -s
Li"* C97Z. 19") and .e (J Jn'Jhc
na «e«ir»t'r1S"JS " """"' Wrt'«'«t« «d tftelr s.ttMn,
1Ut1e Study of asbestos transport in the
appears that the transport of asbestos
n te «a««vr»««. "" ""'"W " the «b«stos minerals
.^is./mLSJrr;,^ ;: ss-ssf.p^'giir
5.1.2 Environmental Fate
lah. * :° the env1ronmental behavior of asbestos; however the fol
deS?^ne?P%rsmentS,are denn1te'y germane with regard ti U
degradation 1n the environment.
m1Jh °972) observe(1 the kinetics of the dissolution of
water over a temperature range of 5 to 45'C A correlation
eonHt5eiKte ?! d1SS°lut1°n 'f «9""«™ <"" the^r e
Hr ?H dr1ft' The rate of the Dissolution reaction was
d rect y proportional to the specific surface area of the asbestos
minerals. It was noted that magnesium cations may be continuously
28
-------
liberated from the chrysotlle fibers, leaving behind an Intact silica
structure. This original structure could then readsorb metal cations,
since 1t will develop a highly negative charge. In general, however, this
readsorptlon of metal cations Is not observed; the smaller the particle.
the faster the magnesium 1s liberated from the asbestos structure.
Moreover, the reaction Is temperature-sensitive only In the Initial stages
of contact between chrysotHe and water.
Hostetler and Christ (1968) determined an activity product of
chrysotlle In water at 25*C of lO"51-0. These results suggest that
chrysotlle 1s slowly soluble 1n water under conditions of continuous
extraction. How applicable these results are to the ambient environment
can be determined only through further experimentation. For Instance,
Chowdhury (1975) studied the leaching of asbestos 1n distilled water and
at body temperature (37°C). He found that, for all practical purposes.
amosite ar.J crocldo'iHe were Inert under these conditions. Nonetheless.
although he was unable to reach a chemical equilibrium after two months of
leaching, a significant amount of the chrysotlle had dissolved (1,000
vsnol of Mg/g asbestos had been leached). He found further that under a
dynamic system, after the magrieslura had leached out, the silica skeleton
began flaking apart, thereby eliminating the asbestos structure.
It appears that asbestos does not have an adsorptlve affinity for the
solids normally found 1n natural water systems; however, some materials,
notably trace metals and organic compounds, have an affinity for asbestos
minerals. The charge-dependent behavior of asbestos can be described by
the concept of the zeta potential, the Isoelectrlc point (IEP), and the
zero point of charge (ZPC). (For a detailed description of these
concepts, see Parks 1967.) The zeta potential 1s a measure 1n mV of the
surface charge of a solid. The ZPC 1s the pH at which the solid surface
charge from all sources 1s zero. The IEP 1s a ZPC arising from
Interaction of H*. OH-, the solid, and water alone. The ZPC of a
complex oxide such as asbestos 1s approximately the weighted average of
the lEPs of its components. Predictable shifts In ZPC occur in response
to specific adsorption and to changes 1n cation coordination,
crystalllnlty, hydratlon state, cleavage habit, surface composition, and
structural charge or ion exchange capacity.
Prasad and Pooley (1973) Investigated the electroklnetlc properties of
amphlbole asbestos dust samples 1n comparison with quartz dust. The
Isoelectrlc-polnt of amosite was found at a pH of 3.1 and that of
croddollte at a pH of 3.3 (Figures 4 and 5). The zeta potential of these
amphlbole asbestos minerals, because of the formation of the fibers. Is a
function of the combined face and edge charge. The face charge will be
due to the silica in the structure, while the edge charge Is due to the
layers of metal cations sandwiched between the layers of silica. Because
of differences 1n fracture, when the fibers are being produced, a
29
-------
-JO -
HO
1-0
7 • » »0 II
Figure 4. Variation of Zeta Potential with pH for toosite Using
the Streaming Potential and Eiectrochoresis Techniques
Source: Prasad«nd Pooley (1973) •
—i—i—i—i—i—i—i—r-
-so
- -JO
T—r
Bnttn»nenvt
7
3 6 T 8 3 '-C
{,«
Figure 5. Variation of Zeta Potential with pH fcr Crtxridolita
Using Streaming Potential and ElecrrcehcresiL1 Techniques
Source: Prasad and Pooley (1973).
30
-------
variation 1n the ratio of face to edge charges Is likely. It 1s evident
from the results that amphlbole asbestos has a ret regatWe charge 1 e
the sum of the negatively charged silica surfaces arti the positively ' ''
charged edges of the metal cation 1s negative. This net charge 1s very
much lower than the actual value of charge per unit area on the fiber-face
surface. The amphlbole asbestos «s. therefore, capable of adsorbing ooth
catlonlc and anlonlc species, the former much more extensively than the
13ttcr.
Chowdhury and Kl'-chencr (1975) found a wide variety of zeta potentials
In natural and synthetic chrysotlles. Strongly positive values were found
1n samples containing an excess of magnesiu» lr the form of bruclte.
Mg(OH)2. Synthetic chrysotlle and natural samples containing 1'ttle or
no bruclte gave moderately positive zeta potentials over the pH range of 3
to 11. Weakly positive or weakly negative zeta potentials were found In
chrysotlles which had undergone weathering (due to natural leaching of the
bruclte layer). Since the pH and the ambient concentration of Mgf< Ions
near the surface are the main controlling factors of the chrysotlle zeta
potential, and since chrysotlle's bruclte layer 1s susceptible to 1e? hlng
In aqueous solution, the zeta potential of chrysotlle 1s a constantly
changing value. These results explain the temporary colloidal stability
of dilute suspensions of chrysotlle 1n environmental media in the mutual
coagulation of chrysotlle and amphlbole asbestos slurries.
This e'fect of the colloidal stability of the chrysotlle was first
described by Naumann and Presher (1968). They Vound that, because of the
positive zeta potential of chrysotlle 1n environmental •sedla, low
viscosity suspensions could be prepared by aeans of the Inherent cf^ige cf
the chrysotlle surfaces. This charge, however. Is so n.jre
chrysotlle that dispersion was obtained only with short fibers and low
fiber concentrations (1 percent). By Increasing the concentration of
certain metallic salts, 1t was found that low viscosity suspensions could
be prepared under aLtiost any environmental condition. These observations
suggest that the presence of trace metals wMl pr.duct a suspension of
chrysotlle asbestos 1n water which will persist uitll sufficient magnesium
has leached from the chrysotlle structure to degrade the suspension.
Furthermore, It 1s probable that under certain conditions asbestos will
persist 1n the water column until Us concentration beccws high enouch to
destroy the suspension or until leaching of the bruclte layer decays the
zeta potential to a point where 1t will become negative.
Ralston and KHechener (1975) studied t*e surfa:e chemistry of amoslte
asbestos. The amphlbole structure of the fiber was found to be resistant.
undergoing only superficial change In aqueous media under normal
environmental conditions. Internal cations are neither leached nor
exchanged. The surface properties of the fiber reserve thosa o* ^ure
silica (quartz): cat'.onlc surfactants are assorted strongly, while anlcnlc
31
-------
asbeftofu tifT' us ' th« ^rfA" che«»stry of anoslte
beh!vcs like "lift" y " Contan1nants. "*"* the fiber Itself
the removal of "bestos *1*ers from drinking
reovna *-?! CMfuUt1on/floceulat1on methods were effective
in removing asbestos rlbers from water. Lawrence et al (1975) found that
coagulation with a 1 ppni catlonlc polyelectrolyte rested In the Jemovaf
?ibjsr2 rsjy 9M?erce?i °f the nbers and "hat an *£ rLini r
rJE!t«fnI?c YJS *• Ihc res1dua1 of chry«tlle was explained by
rElrop U « K?K1i1Ve SU!iface charge 1n Contrast to the negative surface
charge of amphlboles. and most other volume was reduced to about 20
J?tal,^1ume- Further reduct1°n m the sediment volume was
u 1% ( 9 PerCf^ f ter 24 hours)' s"93estmg that natural
1s only a powerful force at high asbestos fiber
(t.d'SiV1?0 ;°und that the «'«t'o: of'ciitS d,atomite
IncJeSlnl ?hf n^ i Jjumlnum hydroxide) was quite effective 1n
f!£nS *!?? tne floccu atlon of asbestos fibers. Schmltt et al. (1977)
Ai !er*Se!1rntat1op> the addU1on cf a Positively charged
further a"regation °f the
behav1or of asbestos from contaminated
.
5.2 Identification Of Principal Pathways of
"posurc are connonly addressed In exposure
The
asbestos-contaminated vermlculHe 1s Inhalation (Section 521)
™??1?i S6CV0rt$ 2ddr"s the Possibility of ingestlon of asbestos from
vermleullte releases Into the environment (5.2.2) and the likelihood of
dermal contact leading to exposure (5.2.3). niteiihood of
5.2.1 Inhalation of Asbestos-contaminated VermlculHe
Airborne emissions of vern-lrullte constitute a minority of releases to
the environment (See Section 4.C). However, the asbestos fibers In these
Ttlll^ aPVS"!SteK and read11y trans?°rt^ through the ambient
atmosphere. Asbestos fibers of resplrable sue* (<10ym) are small and
settle very slowly (Sawyer and Spooner 1978). Atmospheric transport
32
-------
processes therefore tend to lead to exposure via Inhalation of ambient air
near point sources of verm1cul1te discharges, as well as from nonpolnt
sources (e.g., agricultural aid horticultural applications).
These point sources of atmospheric vermUullts discharges are
numerous: they Include the four mines as well as the 47 cities with
exfaliatlon facilities. Exposure from these sources may be occupational
(for those working at the sites) or ambient (for those living near the
sites). Transportation and disposal of verralcuUte may also result In
-------
-
'•'•> —. uso, «••
of
directly.
broken and fiber entered thl
34
-------
6. MONITORING DATA AND ESTIMATES OF ENVIRONMENTAL CONCENTRATIONS
vermkulite (USEPA 1980a)
t df*« saps that could be filled only by monitoring
MK res?U: the EPA-°TS F1eld Stud1es Branch Vitiated a study
»?6S«? bUrk Verffi1cu11te "mples and In mining and mining
2); The mon1tor1"9 Pr°J«t team initially planned to
the !™ip?f olf* °!) 21?!!?5 " We11: Dr''or1ty sh"ts during the course of
nl?nK i *PH*C!"^ th1S Phase of the stud*« Chough two exfoliation
Plants located with beneflclatlon plants were sampled.
h r!)S^tute (MRI> "ortlMted the efforts of Ontario
and »T Research Institute, who were responsible for
™ C Hei'Ults °f th1$ mcn1tor1n9 study are sunnarlzed In
•il * . T?C reader 1s referred to the MRI (1982) report.
Ff fe modeling team of EPA's
Chi«i p«e °KP- rn?er the d1rect10n <>f fe modeling team of EPA's
oJ vlr™ r ?J* f \ Estimates of levels encountered during consumer use
product use dltS "^ *"** UP°n monUor1n9. materials balance, and
Monitoring of Mining an(j Hllllna Facilities (HRI 19821
x °n Ve^]cul1te hav* been gathered by Midwest Research
B er a" EPA contract- s*"Ple analyses were conducted for
0ntaMO Research Potation (ORFJ and IIT Research Institute
.
The original scope of the study Included two phases. The first phase
was the collection and analysis of air and bulk samples associated with
vermlculHe ore and beneflclated vermlcullte at U.S. ports of entry and
from the four U.5. vermlcullte mines. The second phase Included a similar
effort for a representative number of exfoliation plants.
Because of priority shifts within EPA. the second phase was not
undertaken and thf scope cf the first phase was reduced. Sampling trips
were made to the rf.R. Grace mine and milling facilities, near Llbby
Montana, during October 21 through 26, 1980; and to both the Grace and
35
-------
Patterson mines and processing (including exfoliation) facilities near
Enoree, S.C.. during November 3 through 6. 1980. Both air samples and
bulk samples were collected it each location. Air sampling was of two
types, personal and stationary.
AU samples were analyzed only by phase contract optical microscopy.
and the originally planned electron microscopic analysis was omitted.
Bulk samples considered to be representative of each mine were selected as
"priority" samples for Immediate analysis. This set, comprising seven
samples, Included the head feed for the ore processing mill and, where
size grades were produced, the smallest and mid-size grades. Samples were
analyzed by various techniques Including electron microscopy for fiber
content, with emphasis on asbestlform minerals. The analysis was -done by
two Independent laboratories. It was considered possible that fibers
could be bound between the vernUcullte plates and released by
exfoliation. Therefore, analyses were conducted both on the samples as
received and after laboratory exfoliation to see If additional fibers are
released by exfoliation. Laboratory exfoliation differs from coranerdal
exfoliation 1r> that under the conditions of commercial exfoliation, much
of the fines and heavies are removed from the vermlcullte. The laboratory
exfoliation is done under conditions that produce no sample
fractlonatlon. Thus, much of the asbestos would be removed from the *
vermlcullte during comercial exfoliation, but none would be removed
during laboratory exfoliation.
Density-separated fractions from the bulk samples were analyzed by
optical microscopy (OH) and x-ray diffraction (XRC) analysis. "
Isopropanol-susperded fractions of bulk samples of nonexfollated
vermlcullte and water-suspended fractions of exfoliated bulk samples of
vermlcullte were analyzed by transmission electron microscopy (TEH). The
results of the DM and XRD analyses are summarized In Table 8.
A difference in the interpretation of the analytical protocol resulted
In a variation in the counting procedure. The requirement to count 100
fibers was interpreted by ORf to mean 100 asbestlform fibers, while IITRI
counted 100 particles, defined as fibers by having an aspect ratio of
>3:1. To check teh significance of this coa.itIs; variation, two samples
with different fiber characteristics were elected for each laboratory to
repeat the analysis using the alternate PI raouf. These samples Included
grade 5 samples from Llbby, Montana, and f on E.n.ree. South Carolina.
Table 9 Is a summary of tne TEM analysis cf the selected samples and
Includes the number of fibers and their conce.itration in parts per million
as determined by tha two laboratories.
The results suggest that there are more asbestiform fibers associated
with the smaller size grades of vermlcullte than with the larger grades.
Both dust samples collected at Llbby were found to have a very high
36
-------
Table 8.
Surmary of Optical Hicroscopy/fcTO Analysis Sesults
Fibrous phases
a Estimated Mineral
^-^
Libbjr Grace
Grade I , 270-1
Grade 2, 276-1
Grade 3, 255-1
Grade 4, 282-1
Grade 5, 264-1
Grade 5 (1-day), 267-1
Head feed, 291-1
Extract, 294-1
Baghouae mill, 297-1
Screen plant, 288-1
S.C. Grace
Grade 3, 430-1
Grade 4, 433-1
Grade 5, 427-1
Mill feed (+100 aesh),
436-1 '
Grade 3, expanded, 439-1
Grade 4, expanded, 442-1
S.C. Patterson
Ungraded, 573-1
nass. i
4-6
4-7
2-4
0.3-1
2-4
2-5
21-26
1-4
8-12
2-5
< lb
«.'
< lb
< 1
< l
< lb
< 1
l types
Trem-actin
Trea-actin
Trea-actin
Trea-actin
Trem-actin
Trea-actin
Trea-actin
Trea-actin
Trea-actin
Trea-actin
Mixed
Anthophyllite
Trea-actin
Mixed
Anthophyllite
Trea-actin
Mixed
Anthophyllite
Trea-actin
Mixed
Anthopbyllite
Trea- a c t in
Mixed
Aathophyllite
Trea-actin
Mixed
Aiithophyllite
Trem-actin
Mixed
Trem-actin
Anthophyllite
-
Konfibrous amphiboles
Estimated Mineral
nass, '
1-3
3-5
< I
1-3
2-5
4-8
< 1
6-9
1-3
2-6
1-4
2-4
< 1
1-3
1-4
4-6
2-4
1-3
6-9
< 1
< 1
< 1
0.5-1
4-8
8-12
1 types
Trea-actin
Trem-actin
Trea-actin
Trea-actin
Trea-actin
Trea-actin
Anthophyllite
Trea-actin
Trea-actin
Trea-actin
Trea-actia
Trea-actin
Anthophyllite
Anthophyllite
Trea-actin
Anthophyllite
Trea-actia
Anthophyllite
Trea-actia
Anthophyllite
Trea-actin
Anthophyllite
Trea-actin
Anthophyllite
Trea-actin
saaples.
are for composite
b Fiber bundles were mixed phase naterials-both anthophyllite and
treaolite-actinolite were present.
Source: MRI 1982.
37
-------
Table 9. Sunnary of Electron Microscopy Analysis
Priority
SMple Mmple
libby Grace
Grade 1
270-1
Grade 2
276-1
Oridt 3 P
259-1
259-0
259-1
259-0
Grade 4
282-0
282-1
282-0
Grade 5 P
264-1
264-0
264-1(0)
264-0(1)
26*-I
26.-0
264-1(0)
264-0(1)
Head feed P
291-1
291-0
2S1-I
Extractor
294-1
Mill dvut
297-0
297-1
Screening duit
288-0
288-1
Aoalysia,
exfoliated
DO
X
X
X
X
X
X
X
X
X
X
X
yes
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Asbestifora fibers, all lengths
Azpaibole
fibers/g
ic 10s
31.6
23.4
38.9
25
42.0
59
1
65
1.8
118
100
127
98
142
160
119
110
62.5
130
73.8
55.0
100
777
300
1,800
Chrysotile
Mass fibers/ g
(ppa) x 106
78
48.5
210
59
250
240
1
460
17
840
600
1,200
570
2,600
1,800
350
2,600
670
690
590
420
4,600
35,000
3,000
41,000
0.9
0
0.9
< 2.1
0.4
< 1
0
< 0.4
.
< 1.4
_
_
< 1.6
< 1.6
1.4
1.2
0.7
—
•
< 1.6
(ppa)
3.5 x 10"3
0
0.01
- _
6.1 x 10"3
«•
0
•
_
—
^
m
m
•
•»
m
0.13
< 1
3.4 x 10~3
^
^
.
-
(continued)
Source: MRI 1932.
38
-------
Table 9. (continued)
a Priority
Staple saarple
S.C. Grace
tfrade 3 P
430-1
430-0
430-1
430-0
Grade 4
433-1
433-0
433-1
433-0
Grade 5 p
427-1
427-0
427-1(0)
427-0(1)
427-1
427-0
427-1(0)
427-0(1)
Bead feed ?
436-1
436-0
436-1
Grade 3 exfoliated
439-1
S.C. Patterson
benefieiated
Ungraded p
573-1
573-0
573-1
573-0
Analysis,0
exfoliated
no
X
X
X
X
X
X
X
X
X
X
X
X
yes
X
X
X
X
X
X
X
X
X
X
X
Asbestifora fibers, all
Aophibole
Fibers/g
x 108
1.0
2.7
3.1
2.4
1.6
2.7
3.1
2.7
0.6
17
3.0
31
3.5
2.9
3.2
2.4
0.3
12
1.3
11.7
0.03 3.7
1.7
0.5
1.1
Mass
(ppra)
0.55
< 1
3.7
1
6.5
35
1.4
2
1.5
37
4.8
130
4.1
120
7.3
9
0.49
22
0.81
-
XIO'4
27
3
4
lengths
Chrysotile
Fibers/g 1^35
x 10a (pp.)
0.1
< 0.3
< 0.5
^
< 0.3
< 0.3
—
2 6
*• • V
0.07
2.6
< 0.3
0.9
^
0.3
-
0.03
< 0.3
0.2
< 0.3
5 x 10~*
^
m
m
m
—
^
^
_
1 x 10"4
< l
*
»
< i
_
< i
-
1.4 x 10"4
•
5.3 x 10"3
a The "I" and "0" following the sample nuaber indicate the analyzing labora-
tory, IITRI and ORF, respectively. The "(I)" and '"(0)" indicate the
counting procedure, e.g., 264-1(0) are the results from IITRI u.«ing the
ORF procedure.
Seven saaples were designated as priority samples for complete analysis at
the tiae the program was reduced in scope.
0 Analysis was conducted on the samples as received and following laboratory
exfoliation, which unlike cooaercial exfoliation, does net cause sample
fractionation.
39
-------
amphlbole content and Indicate that considerable asbestos 1s removed from
the vermlcuIHe during beneflclatlon. The South Carolina vermlculHe
appears to contain substantially fewer asbestlform fibers than does that
from Llbby, Montana. The laboratory-exfoliated verratcullte samples do not
appear to contain significantly more asbesttform fibers than did the same
samples analyzed before laboratory exfoliation.
Table 10 1s a sunwtary of the phase contrast results of the air
samples. Only one of the analyzed air samples exceeded 2.0 f1bers/cc.
However, the rainy weather conditions at the time of sampling for all
three locations might have resulted in lower than normal fiber counts.
KRI concluded that the IITRI and ORF results were In general agreement
within the expected range of variability of the methodology. However. It
can be seen from Table 3 that their results often differ by as much as an
order of magnitude. These data are Included In the summary of monitoring
data seen In Table 11.
6.2 Monltorlno of Exfoliation and Product Formulation
CSHA has monitored fiber levels at the O.H. Scott plant In Marysvllle,
OH. The data are summarized 1n Table 11. Note that '.r.formatlon 1s
lacking on analytical methods.
The following kind: of samples have been collected:
• Area samples. Samples have been taken 1n the expander
(exfoliation) areas and in other parts of the building. Results
are expressed as total fiber counts: fibers have not been confirmed
as asbestos.
• Personnel samples taken during the performance of various
activities (Table 11). These fibers are presumed to be asbestos.
• Bulk vermlculUe samples from different suppliers and from waste
generation (Table 12).
6.3 Monitoring of Ambient Air Near Mines and Hills
The HRI monitoring study (HRI 1982) Included some area sampling 1n the
vicinity of mines and mills (Table 10, stationary samples). A maximum of
0.5 f/cc was recorded In Llbby about 4.5 km downwind of the mine. A
concentration of 0.03 f/cc was recorded at the H.R. Grace mine 1n Enoree;
0.05 f/cc was reported 100 m down.-lnd of the mill. Levels reached 0.02
f/cc within 50 m of the Patterson site 1n Enoree*.
*01stance from source was not reportad 1n HRI (1982); data Is from
personal coiwrmnlcatlon between Gaylord Atkinson, HRI and John DoMa,
Versar, Inc.
40
-------
Tablo tO. Results of Pheso Contrast Analysis of Air Samples Collected at Thr«« Sites
Sample
tIDDY, GRACE
106 Ftold blank."
133 Field blank0
Personnel sanptes
131 Front loader, mlno
MS Pit haul .driver, mine
136 Mlno analyst, mine
141 Oottom op»rator, mil 1
130 No. 7 operator, mill
139 Oozor opoi'alor, ml no
101 Shuttle truck, botxoon
scruunlncj eM sizing plant
Stationary sanples
104 Scroonlmj plant, OH
til Scrwunlnj plnnt, DW
108 Trallor court
156 iNo. 9 aut>»fatlon
SO'JTH CAROLINA, GRACE
312 Field blank"
J16 (1 old bl/inK0
M I no personnel sairplcs
310 TrucH drlvur
301 Drag II no operator
Mlno stationary samples
JOT Mtno (H> crosswlnd
J23 Mine (E) demon 1 nil
330 Mine (W) upwind
Sflrnp to
vol. (I)
.
-
303
m
294
276
285
370
385
390
360
169
III
-
-
237
240
291
154
264
ORF
<0,02
0.03
0.02
<0.0t
1.5
1.2
5,1
0.02
O.I
0.08
O.I
O.OJ
0.03
<0.02
<0.02
<0.01
<0.01
<0.01
0.01
0.03
Fibers / ec
IITRI
0.04
0.05
0.04
0.01
1.9
0.4
9.7
0.2
0.2
0..1
0.02
NUb
0.02
0.04
0.02
0.3
NO"
0.02
0.02
0.01
-------
Table 10. (continued)
Sample
Mill and exfoliation pei sonnet samples
340 Mil I monitor
321 Mill lat> technician
347 No. 4 baggor, exfoliation
330 No. 3 bagyor, exfoliation
Mill stationary samples
328 Mil 1 (END downwind
335 Mil 1 (N) crossulnd
300 Scroonlng plant floor
SOUTH CAROLINA. PATTFRSON
505 Field blank8
5J3 Field blank*
Donof iclatlng and expanding
Porsonnol Sdnplcs
500 Pay 1 cod operator
520 Plant foreman
542 Oagger/forkllft
Stationary Sdnples
513 (NE) downwind
506 Control off-site
515 (SE) crosswlnd
523 (SH) upwind
Sample
vol. (U
340
478
314
285
207
80
354
.
-
255
252
249
188
274
299
147
Fiber* / ec
ORF
0.03
0.07
0.06
O.I
0.05
0.04
0.06
<0.02
<0.02
-------
Table 11. Sumary of Monitoring Cat* for Asbestot-coAUlnlng v«nnlcullt«
Population
Sampling and Wurrt>ar
analytical of
methods observations
Oftf*
Asbestos fiber
.. concentration, f/cc
IIIRlb NIN HCAN
MAX
CoranenU
I. OCCUPATIONAL
A. Miners and millers of
vermleullte
« Grace mine and mill at
Libby (MM 1982}
PS.
OH
• Grace mine at Enorce
(NR! 1982)
• Cracc mi 11 at Enoree
(r«l 1982)
• Patterson mill
(see 1C.)
B. Importers and exporters of
vermlcuJUc
C. Exfollators of vcrmieulUe
• Grace facility *t Enor«>
(mi 1502}
• Patterson facility
'.benefl elation,
exfoilAtton) at Enorco
(HRI 1932)
PS,
ON
PS.
OH
PS,
PS.
ON
0.02
0.01
1.5
1.2
3.1
0.02
O.I
-------
Tabl« U. (continued)
• O.K. Scott. OSHA personnel PS
(OSIM 1979)
• O.H. Scott. OSHA area
(OSIM 1979)
0. Users of unexfolidted
varmlcullte
AS
10
II
22
12
9
6
12
24
24
2
I
1
2
NO
NO
NO
NO
NO
NO
ND
0
0
NO
0.21 Screens «nd«11 It
0.35 Screws And mtlit, blender
0.21 Cleaning dryer
0.19 Paddle mixer, dryer
0.096 Control operator
0.044 Feeder operator
0.30 Process operator, txpander
ire*
1.1 Track unloading area
0.036 Packaging
NO Durplng, rcblend, and
sweeping
ND Ironized control roan
NO Warehouse: receiving area
ND Warehouse: mid-aisle
NO Polyform track area
1. Steel workers,
2. Manufacturers of gypsum
wallboard
(a) Wholesale/retail
traders of wdllboard
(b) Installers of wall-
board
E. Users of exfoliated
vermiculite
1. Producers of lightweight
aggregates
(a) Users of plasters,
concretes, and
aggregates containing
vermiculite
-------
T*bl« N. (continued)
(b) Wholesale/retail traders
of lightweight aggregates
2. Producers of vcrmlcultto
Insulation
(a) Users of vermiollte
Insulation for loose HI),
block fill, and packing.
(b) Wholesale, retail traders
of vermicuUt' :nsulatlon
3. Producers of agricultural and
horticultural precis contain-
ing vcrmlculltc
• O.H. Scoll (sco l.C.)
(a) Users of agricultural and
horticultural products con-
taining vcrmlrulite
(1) tKcrs of pesticides
and fertilisers
(1) Users of horticultural
media
(2) Users of cattle feed
(3) Users of hatchery and
poultry litter
(b} Wholesale/retail traders
of agricultural and horti-
cultural products contaln-
Inq
-------
Table It. (continued)
4. Producers of minor vermlcul He-
containing products
(a) Producers of vermicuUte
filters for pollution con-
trol and similar uses
(1) Users of vermicullte
filters In waste-
Hater treatment
(Z) Users of vermicuUte
for nuclear waste dis-
posal
(3) Users of veimicuHte
filters for air
purification
(b) Producers of oil well dril-
ling muds
(1) Well drillers
(c) Producers of art.Mclal dust
and fireplace ashes from
vermSculite
(1) Hotion picture industry
workers
(d) Producers of refractories
and firebricks
(1) Users of refractories
" and firebricks
(2) Miscellaneous users of
vcrmiculitc products
-------
11. (continued)
(3) Hiscellaneous wholesaler/
retailers of vermlculite
products
5. Transporters of vermlculite
(a) Tnjclr drivers PS, 1 <0.0l 0.3 See l.A.
(b) Ship and dock
vwkors OH
(c) Rail workers
(d) Warehousemen AS 0 Sec I.C.
II. TRANSPORTATION AND STORAGE
SPILLS
III. CONSUMERS
A. Homeowners insulating
attics
»
"* B. Users or lawn and
garden fertilizers
C. Users of hrosoplant
potting soil
D. Users of kitty litter
E. Users of vermicuUte
In barbecue grills
IV. DISPOSAL
V. FOOD
VI. DRINKING WATEK
-------
Table II. (continued)
VII. AMBIENT ENVIFtONMEMl
A. Air
1. Concentrations around
mines and mills {MRI 1982) OH 13 <0.01 NO- Within 5 km of source
0.1 O.S
B. Watei
C. Soil
'ORF « Ontario Research Foundation analysis of split sample.
bIITRI * IIT Research Institute analysis of split sanple.
NO - Not detected.
*» OM » Optical (phase contrast) microscopy.
03
PS * Personnel sanple.
AS m Area sanple.
-------
Tabln 12. Asbestos in Bulk S«ples tram O.K. Scott and Soot Co.
Source
Libhy (uncxfolidled)
libby (oxfolidled)
S. Africa (exfotidled)
Cyclone waste
Dryer waste
C'Mitral vaciiiin waste
Source: OSIIA, 1979.
Analytical rwthod
Led) unkrtokn
1) unknown
)l idled) unknown
died) unknown
unknown
unknown
isle unknown
No. of
observations
2
2
1
1
2
4
1
Asbestos
detected
none
none
none
none
none
none
none
-------
6.4 Estimates of Environmental Concentrations of Asbestos from
Verm1cul1te
Because the primary exposure pathway for asbestos relejsed by the
mining processing, use. distribution, and disposal of vermlcullte 1s via
Inhalatlo-. atmospheric concentrations of asbestos are central to the
developmer,k of an Integrated exposure estimate. Two basic types of
emissions can result 1n exposure: (1) releases during exfoliation, and
(2) releases during the use of verm1cu11te-conta1n1ng products. Estimates
of atmospheric concentrations resulting from these emissions are discussed
In Sections 6.4.1 and 6.4.2. Atmospheric modeling In Section 6.4.1 was
performed by Scott Relngrover of General Software Corporation and Bill
Wood. Joan Lefler. Loren Hall, and Annett Hold of the Chemical Fate Branch
of EPA/EEO. No effort 1s made to differentiate concentrations for
different fiber sizes of asbestos, despite the fact that fiber size may
affect risk, because the assumptions and available data underlying these
estimates are too crude to support this type of analysis.
6.4.1 Releases from Exfoliation Plants*
The releases from the model exfoliation plant described In the
regulatory options document (GCA 1980) were used to represent source
strength st exfoliation plants. Emissions were assumed to occur uniformly
over a year. The mode? plant rates were dted without a particle size
breakdown. The asbestos fibers of respirable size are of concern, and
these are much smaller than the vermlcullte particles of large enough
slzefor the commercial grades. 'It was assumed that the releases escaping
the baghouse provide an estimate of the quantity of resplrsble particles.
The basis for the assumption Is that the baghouse would tend to trap
larger particles.
Emissions from the baghouse were cited as 0.58 kg/hr (0.16 g/sec) of
vermlcullte and 0.026 kg/hr (0.01 g/sec) of asbestos. Other engineering
data were not documented, but the effluent from the exfoliation furnace to
the baghouse was estimated to be 5,200 ft3/m1n (2.45 nrVsec), escaping
the baghouse at 300°C. The work year for the plant was 6,000 hours.
Exposure estimates were made assuming emissions of 0.01 g/sec continuously
for a year. This assumption of continuous emissions does not take Into
account the 6,000-hour work year; modeling results may therefore be
overestimates by more than 50 percent, and should thus be considered
worst-case averages.
The Atmospheric Transport and Diffusion Model (ATH) (Culkowske and
Patterson 1976) was used to provide estimates of annual average fiber
concentrations surrounding the model exfoliation plant. Input parameters
for the ATM simulation are presented 1n Table 13. Heteorologlc conditions
*Port1ons of th*s section were provided by Annett Nold, EPA/EEO/CFB
(1961).
-------
were based on wind rose data for a weather station \n St. Louis.
Missouri. Deposition processes. Including washout, were Included. Two
simpler models were also used to bracket exposure levels. The results are
summarized 1n Table 14. Worst-case concentrations, which would exist for
short tlae- spans (approximately an hour), were also estimated using a
simple 6auss1an plume model, PTMAX (Williamson 1573, Turner 1969). The
wjrst-case results are on the order of 1 to 10 vg/m3 (see Table 14).
The annual averages provided by ATH are of greater utility for estimating
cumulative exposure. The ATM generates annual averages for sectors
surrounding the source using wind rose data. As a rule of thumb, the
annual averages near the source tend to be two orders of magnitude less
than the worst cases found by PTMAX. and this was roughly true In tMs
study. The position and magnitude of the maximum concentration are
sensitive to wind speed and direction and atmospheric stability. For the,
St. Louis wind rose, the maximum moves around the geographic area rather
than remaining localized, so that averages are much lower than the
maxlimra. Sensitivity with respect to source height and temperature was
tested with additional trials of PTHAX and ATM; near-source conventrat1ons
from ATM vary over almost an order of magnitude but concentrations more
than a kilometer away are much more stable.
The National Oceanographlc and Atmospheric Administration's
Atmospheric Turbulence and Diffusion Laboratory box model (ATOL) provides
a simple representation of annual average pollutant concentrations near a
point or area source. The model Is based on centering the source In an
area defined by the programmer; 1n this case, a box 20 km by 20 km wide
and 150 m h'gh was chosen. These dimensions approximate the distance
within which fibers from the exfoliation plant nay contribute
significantly to background. Emissions of 0.01 g/sec asbestos Into a wind
velocity of 5.5 m/sec were used; this represents age meteorological data
for St. Louis. Results (Table 14) are within the range predicted by ATM.
Figure 6 is a reproduction of the ATH printout for this facility data
are generated for each of the 10 distances from the source and the 16 wind
directions^ Population data are Included for each of the wind rose
sectors; these data ars> retrieved via a computerized Interface with
SECPOP. a fUe^ofJJureau of Census data. Figure 7 summarizes the averages
and extremes of the concentrations estimated by ATM, and Illustrates the
rapid decline 1n levels as distance from the source Increases.
It is assumed ^ that the St. Louis meteorological data and the model
plant emissions will produce estimates of the environmental eonrMfp.
°'
, s s ' r
ss ''
52
-------
Table U. tto
-------
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CUU*CC I >«Ul>l Ctl. - *T. LOUIS. U3 MtUIO* TfM » MCMMt
t rartiMTlos Eixjeunt (K/T*>
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t.ta»«4 l.
••« 142.« i.«j..-oi i.oitr'Ci 4.
» 4.«»-t-7J J.7«£.U} l.7«£-9) t.ltlC-el 1.»(2f«4 2.IIIC-44 1.4)01-01 1.444C-OS
j . ...l?l1 ' " 1S5S H34 U^S* ^144? 4t«Tt 170j»
UL
7.«44C»«t
Figure 6.
for
54
-------
JOUTHWUTHCTOR
iiowfir co«cs.rnuTT3»)
Figure 7. Atmospheric Transport Model (ATM) Annual Average Asbestos Concentrations
-------
6.4.2 Releases front Use of Products Containing Verra1cul1te
Asbestos concentrations to which consumers nay be exposed were
estimated for three applications of vernrlcullte; these Include loose-fill
Insulation In attics, a component of garden fertilizers, and a component
of lawn fertilizers and herbicides. These uses were Identified as having
tha most significant consumer exposure potential. Verraicullte's use as an
aggregate results largely in occupational exposure during application of
plasters and concretes. Once 1n place, the vermlcullte 1s contained
within a oatrlx and will not release asbestos fibers.
(1) VermlcuUte Loose-fill Attic Insulation. The calculations of
asbestos concentrations generated by homeowner Installation of vernricullte
Insulation In attics were based on engineering assumptions, monitoring
data, materials balance Information, and experimentally-determined release
rates. It was assumed that the rate of vermlcuUte application would be
constant over an eight-hour period {the duration cited by JR8 (1982)). No
air exchange was factored 1n, and 1t was assumed that all fibers released
would rema'n airborne.
The materials balance data furnished by JRB (1982) Indicate that 510
kg of vermiculUe are used 1n an average attic, which would have a volume
of 158 m3. It Is assumed that 1 percent of the bulk vermlcuUte (of the
grades used 1n Insulation) 1s asbestos. This assumption 1s based on the
data In MRI (1982), although few samples of exfoliated vermlcuUte were
analyzed. Some exfoliated verrakulltes will contain less than 1 percent
asbestos. One percent 1s used as a reasonable worst case.
The release of dust Into the air was estimated by simulating the
pouring and spreading action Involved 1n Installation.
Horticultural-grade vermlcuUte was obtained; it 1s assumed that It 1s
roughly equivalent to that used for Insulation. The vermlcuUte was
weighed on an electronic balance accurate to 0.1 g, poured, then
rewelghed. The amount lost was the dust that did not settle Immediately
after pouring, and made up 0.0425 percent of the total mass.
If 510 kg of vermlcuUte are applied evenly over e*ght hours, the
hourly rate 1s 510/8. or 63.75 kg. The hourly asbestos release to the
atmosphere 1s calculated by multiplying the release rate, percent
asbestos, and the application rate.
0.000425 x 0.01 x 63.75 kg => Q.OOO'.V kg
n fti>SA'15«jf Itt1c volume' *&* C0ncc"trat1on after one hour would be
0.00027 kg/158 m3 Or 1,700 vg/nn. If no fibers settled 1n the
eight-hour period of application, the concentration of asbestos 1n the
attic would reach 13.&00 pg/m3 (see Figure 8).
-------
(3
U
15.000.
11,500-
1JJM-
I0.MP-
9O»-
7500 -T
S
w
1 MM-
4500-
3000-
1500-
3 45
TIME (HOURS)
Figure 8. Estimated Asbestos Concentrations During Installation ot Loose-Fill
Vermlcullte Attic Insulation
57
-------
Th" assumptions Involved 1n this calculation make H a worst-case
estimate; It 1s probable that some of the dust will settle out, and
ventilation ^n the attic will remove some of the dust. The lack of
particle sUe data prevents use of settling velocity data (such as that
shown In figure 2).
(2) VeratlculUe-carrler Garden Fertilizers. Atmospheric
concentrations of asbestos resulting from the use of verralculHe-based
fertilizer In gardens were estimated, based on product Information.
monitoring data, engineering assumptions, and experimental results.
A dust release rate of 0.0643 percent was obtained by weighing a bag
of garden fertilizer before and after pouring; some air movement was
simulated during the experiment. It was assumed that the dust composition
was Identical to the product formulation given on the package; therefore,
about 20 percent of the dust was verralcullte, of which one percent 1s
asbestos fibers.
The 10 Ib. bag of fertilizer 1s designed to treat 600 ft*, which is
assumed to be the area of an average garden. Release of dust 1s
continuous over the area, and all fibers are assumed to remain suspended
In the air.
Treatment of a 600 ft2 garden with a 10 Ib. (4540 g) bag cf
fertilizer will result 1n the release of 0.0058 g of asbestos fibers:
.000643 (dust release x 4540g x .20 (percent x 0.01 (percent - O.GOSBg
factor) vermlcullte) asbestos)
If this asbestos fiber concentration 1s contained within the immediate
area of application, the volume of air affected may be estimated as
600 ft* x 6 ft or 3600 ft3 (102 m3);
this simple box model provides a worst-case approximation of short-term
concentrations.
The concentration of asbestos fibers released from garden fertilizer
use 1s therefore:
0.0058 g * 102 m3, or 57 ug/m3.
This concentration 1s the accumulation of all the fibers released during
application and 1s the maximum that might be expected. A concentration of
28 yg/m3 would be expected after half the fertilizer 1s applied; a
linear function such as that seen In Figure 8 1s assumed 1n this model as
well.
58
-------
, {3> Vermleume-r.arrler Lawn Fertilizers and H»rMr^»c The re lease
rate (0.0643 percent) obtained for garden fertilizers was also used 1n
this approximation. Other factors remain the same, with the exception of
product-specific Information:
• IS percent of the product 1s vermlculUe. approximated from package
Information and patent formulation data (U.S. Patent No. 3,083.039}
• 7.6 kg treats 465 m*. from package Information.
It was estimated that the average lot size 1* one-qua-'ter acre
(1010m2). The asbestos released from lawn fertilize"- application car, be
estimated:
0.000643 (dust release x 760Qg product x 1010 m* x 0,15 (percent
rate) 46552 verralculUe)
x 0.01 (percent' » 15,900 yg
asbestos)
A box model (1.8 m by 1010 ra?, or 1918 m3) *s used to calculate the
asbestos concentration after all fertilizer 1s applied:
15.900 ma * 8.7 pg/m3 asbestos
1.818 at*
The concentration after one half the fertilizer had been 3Dp11<><< would be
4.4
This type of simple model assumes that mixing Is homogeneous and
Instantaneous wltMn the box; although this 1s not a valid assump-don. It
serves the purpose of estimating worst-case exposure.
59
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7. EXPOSED POPULATIONS
The following section presents the best available data concerning the
number of persons exposed to asbestos-contaminated vernlcullte. In wany
cases, the data apply to the total numbers of producers and users of
vermlcullte; no attempt Is made to estimate the proportion using the
asbestos-contaminated mineral. Section 7,1 lists the
occupatlonally-exposed populations. Section 7.2 deals with consumers of
ve-m1cu11te products, and Section 7.3 estltaates the population exposed to
asbestos via ambient air near vermlcullte emission point sources.
7.1 Occupational Populations
7.1.1 mners and Millers
There are four active vermlcullte Bines In the U.S.: H.R. Grace In
Ubby. Montana; Grace 1n Enoree. South Carolina; the Patterson
Vermlcullte Co., also In Enoree; and Virginia Verimcullte 1n Louisa
County, Virginia. The Grace mine In Llbby produced 181.000 kkg of
vermlcullte 1n 1979 {3RB 1982). Ore Is mined by bench quarrying using
power shovels and ancnonlum nitrate blasting. After raining, 1t Is hauled
by trucks to a nearby primary processing plant and then to the mill (JRB
1S82). The Llbby mine employs 250 persons (EIS 1980). Th^ Grace olne at
Enoree produced 119,000 kkg 1n 1979 (JRB 1982). Ore Is mlnet! from
several open pits, exploited with little or r,o blasting. It 1s then
hauled by trucks on public roads to a central concentrating mill (JRB
1982). Based on operations at the Llbby mine, M 1s assumed that the
Grace mine at Enoree employs 200 persons. The Patterson VermlCv'llte
Company mined 5,000 klcg 1n 1979 {JRB 1982). The ore Is mined f,-oa open
pits and hauled by trucks to the mill two ralles away (JRB 1S6?).
Patterson has between 20 and 49 employees (EIS 1980). The Virginia
Vermlcullte mine began operations 1n 1979. mining 9,000 kkg (JRB ".982).
Further data are unavailable. Using figures for Patterson as a gulie. 1t
1s assumed that the Virginia nine employs between 20 and 49 person..
The total number of employees Involved 1r, verrolcullte mining and
milling Is between 490 and 548. Over half of these workers are expe-ted
to be non-operating support personnel (Hunslcker and SUtenfleld 1973)-
therefore, these figures are an upper ;im1t for exposure.
7.1.2 Exfollators
There are 52 vermlcullte exfoliation plants In 32 states {JRB 1<^21
iB t^MISK' f°r I''?!/"antS (See T3ble 15) repre**° « "pJir
limit for possible vermlcolHe exposure. Populations ray be
overestimated for the following reasons: {1} floares Include cler1c«l '
personnel who inay not be directly exposed and (2) non-vermlculUe
Preceding page blank 61
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Table 15. location, Enplopent, and Products of U.S. Exfoliation Plants
tone
location
Nunber of
employees
Product
Brouk Co.
Cl aval and Builders Supply Co.
Diversified Insulation Inc.
J.P. Austin Assoc., Inc.
W.R. Grace Co., Construction
Products 01 v.
W.R. Grace Co., Construction
Products Dlv.
W.R. Grace Co., Construction
Products 01*.
W.R. Grace Co., Construction
Products 01v.
W.R. Grace Co., Construction
Products Dlv.
H.R. Grace Co., Construction
Products 01 v.
W.R. Grace Co., Construction
Products Dlv.
tt.R. Grace Co., Construction
Products Dlv.
W.R. Grace Co., Construction
Products Dlv.
St. touts, MO
Cleveland, OH
Minneapolis, lot
P-avar Falls, PA
Irondale. AL
Phoenix, AZ
torth Little Rock. A* 35
Nsnark, CA
Santa 4»a, CA 200
Denver, Co
Ponpano Seach, FL 25
Jacksonville, FL 36
Tarapa, FL 75
Insulatfon
exfoliated varmlcuti!-»
concrete products
crude petroleun; oil and gas
exploration; exfoliated
vemtoil ite
chemicals
exfoIi ated vermIcu11ts
fertilisers
62
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Table IS. (Continual
MM* Location Numbsr of Product
t»R. eraei Oo,. Coftstracttoft
Products Civ.
K.R. Sracw Co., Construction
fVoducts 01 v.
K,R. Grac* Co.. Construction
Products Bl*b
W.R» Srec* Co., Construct U»
ft-oducts 01 v.
W.R. Grace Co., Construction
flroducts 05*.
V.R. Grace Co., Construction
Products SI*.
W.R, Grace Co., Constnictton
tVodacts 0!v,
W.R. Srace Co., ConsTructJon
fVoducts 01 w.
K.a, Grace Co., Conitructlon
(Voducts 01 v.
W.R. fir*c*0e*» Construction
Rroducts Dlv.
K.R. Sr«c» Co., Construction
Products Civ.
W.S. Graeo Co., Cons true 1 1 co
K^,^ ^, •«.**• "li i.
W. Chicago, It 20 axfoHBted verm! cu lite
N»»t«ort» KIT 20 tnstilatlon
ben Or-S«aos, tA 100 construction Mtartals
6«ltsv1II«, HO 20
EasthaiwtOB, HA 20 **.U
-------
Uole 15. (Continued)
Location
Number of
eiployees
Product
W.R. Grace Co., Construction
Products Dlv.
V.R. Qraca Co., Construction
Products Dlv.
K.R. Grace Co., Construction
Products Olv.
H.R. Grace Co., Construction
Products Olv.
N.3. Grace Co., Construction
Products Dlv.
W.R. Grace Co., Construction
Products Dlv.
H.R. Grace Co., Construction
Products Dlv.
Oklahoma City, OK
Portland, OR
Ho* Castle, PA
Kearney, SC
Travelers Rest, SC
Enoree, SC
ttosnvtlle, TN
K.R. Grace Cs., Construct Ion San Antonio, TX
Products Dlv.
W.R. Grace Co.. Construction Dallas, TX
Products Olv.
W.R. Grace Co.. ConstrucTlon Milwaukee, Wl
Products 0!v.
International Vermlcullte Co. Glrard, IL
133
20
Koos Inc.
Ksnosha, Wl
21
20 - 49
100 - 249
equlp*ent rental and leasing;
crude petroleum, oil and gas
eaqjforatton, oil field and
other aachlnas
plastic products
exfoliated vermlculIte
insulation; also
fertilizers
(105
soap and detergents
chocolate and cocoa,
exfoliated vernlculite
alnerat wool
agricultural chemicals
64
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Table 15. (ConttwwG
Nam
lecatton
of
wplcjees
Product
Mica Pellets, Inc. Oe Kalb, IL
Robinson Insulating Co, Great Foils, MT
Robinson Insulating Co. ' Ml not, NO
Schundler Co. Itotuchen, NJ
O.M. Scott Marys/tile, OK
Strong-Ute Products Pine Bluff, AK
Verllte Co. Tanpa. fl
Vermiculltei of Hawaii. Inc. Hjnolulu, HI
Vernlcullte Intenrxintaln, Inc. Salt take City, UT
Verrnlculita Products, Inc. Hauston, TX
A.B. Dick Denver, CO
Diversified Insulation Wellsvllle, KS
Lite Height Products
Patterson Vernlculits Co.
Virginia vermlcultte
Kansas City, KS
Ehoree, SC
Uxilsa Co., VA
20-49
Insulation
Insulation
20 - 49 concrete block and brick.
1.000 - 2,499 fertilizers
50 - 73 building paper and
board nil Is
a Probably Included In nvinlng population figures (see Taaie U).
Sources: EIS 1980.
ORB 1932.
OSH/V 1979.
-------
containing products may also be manufactured at the plant; these products
are listed 1n the table when they are known. Persons Involved \n
manufacture of such products may not be exposed to verralcuHte.
A typical exfoliation plant has three men In operations and two men
for other work per furnace for each shift (Hunslcker and SHtenHeld
1979). However, not all employees exposed to verralcullte at these plants
are Involved 1n exfoliation. The cost of transporting exfoliated
vermUullte prohibits locating exfoliation plants great distances from
locations of further processing or end use. Therefore, about one third
of all exfoliated verntlculUe 1s formulated Into a final product at the
exfoliation plant. The other two-thirds 1s bagged or shipped In bulk for
subsequent reformulation, rebagglng. or use as 1s by the consumer (see
Table 16). Consequently, workers at the same plant may be exposed to
vermlcuUte by exfoliation, formulation, bagging, loading, or
combinations of these operations.
Some exfoliation occurs at mine sites. W.R. Grace In Enorec Is
estimated to exfoliate 5.000 kkg per year at a plant near the mine (JSB
1982); 133 workers are Involved In exfoliation there (Table 15).
Patterson exfoliates all Us vermlcuUte at Us mill; they ship no
unexfollated vermlcuUte. The number of employees listed for the mine
probably Includes exfollators. Virginia VermlcuUte 1s estimated to
exfoliate 2,000 kkg at the mine site (JR8 1982); the number of employees
involved 1s unknown. No vermlculUe 1s exfoliated at the Grace mine In
Ubby (JRB 1982).
Employment figures are not available for some exfoliation plants
listed 1n Table 15. Based on an average of 120 employees per plant,
calculated from known employment, the total number of workers In
exfoliating plants (excluding the Patterson and Virginia mines) 1s
between 1.694 and 1,979.
7.1.3 Other Occupationally Exposed Populations
Table 17 summarizes the populations exposed to vermlcuUte. Few data
are available on the extent of vermlcuUte use within each Industry.
Therefore, the percentage of workers In each Industry actually exposed to
vermlcuUte 1s often Impossible to determine. Table 17 does Include some
exposure data derived from the National Occupational Health Survey. In
using Table 17, note that exposure resulting from manufacture or
formulation of vermlculUe-contalnlng products at the exfoliating plant
1s Included under the heading "Exfoliation* and Is not differentiated
from exposure resulting from exfoliation per se.
The uses of exfoliated vermlcuUte are numerous, but 98 percent of
consumption falls Into three major categories: lightweight aggregates.
-------
Table 16. Estlnates for Veruileul Ite Transportation fro» Exfoliation Plant
Exfoliated v«ratoillte (percent of total)
End use
Bag
Bulk
Use at plant
Aggregates
Insulation
Agricultural chemical carrier
Q-ovIng mdla
Other uses
TOTAl
24
31
I
7
1
64
12
13
7
I
33
Source: JRB 1982.
67
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17. Summary of Estimated Population Exposure to Vermlcullte*
Population
i. occunmoNM.
A. Mines and ml Her* of vermlcul lt«
0. Inportors and exporter* of vormlcullta
C. Exfollators of vormlcultte
Mumber
of
establishments
4
50
Total Numoer of
nurtrar of persons
persons exposed
490 - 948
1,694 - 1,979
Common t»
EtS 1980
& Versar «»tlmate
EIS 1900
0. Ibers of unexfollated vermlcul I to
1. Stool workers
• Furnaers of oxf oil atari vorml cul I l-o
I. Producers ol I Ighttwlgbt aggrogatds
• Sea I.C.
(a) Users of plasters, concretes,
and aggregates containing
vorml cul I te
• Construction laborers 622
• Comont and concroto finishers 40
• Brick and ttono masons 184
76
863
199,000
Varsar estimate
WHS 1980
NOHS 1980
NOHS 1980
10,753
440
3,000
HOWS 1980
NOHS 1980
NOHS 1980
-------
Table 17. (continued)
Population
• Plasterers
• Dry wall Installers
Hiitiber
of
establishments
382
352
Total
lumber of
persons
Number of
persons
exposed
4,242
16,204
Comments
NOHS ICfiO
NOHS 1980
1C
(b) Wholesale/retail traders of
lightweight aggregates
• 3ulldtng material suppliers
> Producers of vermlcullte Insulation
• Soo I.e.
(a) Users of varmlcullto Insulation
for loose fill, block fl(t, and
packing
• Construction laborers
(Soo I.E.t.(o))
• Insulation workers
• Shippers and receivers
User* of agricultural/
horticultural products
40,600
294,300
Bureau of Census 1980
72
298 NOHS 1080
44,000
Oureau of Census 1980
-------
Ubte 11. (continued)
Population
Number
of
establishments.
Total
nuifeer of
persons
Nwnbir of
persons
exposed
Confronts
containing vermlcullta
3,400
299,000
88,000
112.600
27.000
440.000
2.000.000
2,200.000
Amar. Assoc. thirserym«n*
1981
666 NQHS 1980
Bureau of Censu* I960
470 MOMS 19QO
Bureau of Census 1980
Bureau of Census I960
Bureau of Census 1980
Bureau of Census 1980
Bureau of Census 1980
Bureau of Census 19BO
Bureau of Census 1980
-------
Table 17. (continued)
Population
NUmbor
of
establishments
Total
iunfcer or
persons
of
persons
exposed
Commont»
4. fVoducers of minor vermlcul Ita -
containing products
Producers of veralcullt« fIIters
for pollution control and
slfflllar uses
(I) Users of varmlcullffl filters
In wastewater troatnant
(2» Usa-s of verralcullta for
nuclear waste disposal
• Nuctoar physicians
Producers of oil wt>ll drilling muds
(I) Moll drillers
(c) Producers of artificial du$t and
Mr op loco ashas from vorral cii 111»
(I) HiMon plcfura Industry workers
(d) Pruducors of rafractorles and
firebricks
1,200
9,000
69.000
25
78,000
37,000
AmorIcan Coll* NucIear
Physicians I98lt
Buraau of Census 1980
Bureau of Census 1980
Refractory (net.
Bureau of Census 1980
Bureau of Census 1980
-------
Table U. (continued)
Population
Njmber
Of
establishments
Total
muter of
persons
Number of
persons
exposed
Commits
premlxas
Enamel
Ink
Plastics 149,000 Bureau of Census 1980
Rubber 387,000 Bureau of Consu* I960
Paper
Fabric*
Plywood
(2) Miscellaneous users of vermtcullte
products
• Vtoldors
* Worker* exposed to industrial
• Markers oxposod to vermlcullt*
sound Insulation
(3) Miscellaneous wholesalers/retailers
of vermlcullte products
• Soa I.E.3.(b)
e r»t stores
9« Transporters of vormleultta
(I) Truck drivers 1,900,000 129 Bureau of Census 1980
NOHS 1980
(21 Ship and dock work en
(3) ((all workort
e freight handlers 33 108 NOKS I960
(4) Maroliousemn
1 1. TRANSPORTATION AND STORAGE SPIUS
-------
Table H. (continued)
III
Population
. CONSIMEKS
A. Jtom-jox'ners Insulating atttca
B. Ihors of lawn and gard»r fwrtlllwrs
Number
of
establishments
94. 000
Total
nunfcer of
persons
108,000
< 74,400.000
Number of
persons Conwnnt*
exposed
168,000 Vorsar estimate
SHR8 >80
C. Users of houseplant pottl.-ig soil
• Mbmbers of tbbby Greenhouse
Owners Assoc. of America
• House plant owners
0. Usors of Kitty litter
'.:, Users of vorinlcul Ito In b/irbocua grills
IV. OlSPOSAt
V. FOCI)
VI. DRINKING WATEH
VII. AMBIENT
A. Air
I. Persons near mlnos anr< mill*
2. Persons noar exfoliation sites
3. Rjrsona noar users of vormlcullto
> 3.000
> 46,600.000
15,000,000 - 0.800,000
4.600
4,680
51
t3.M7.496 13,147,496
Encyclopedia of Associa-
tions (1981)
SNRH 1)60
SMRB I960
Estimates bused on Bureau
of Census Advance Reports
for I9SO population
(Bureau of Census 1991)
Bureau of Census Advance
fteports for I960 population
(Bureau of Census 1981)
-------
Table 17. (continued)
Population
of
establishments
Total
nuntoer of
persons
of
persons
exposed
Comments
I). Wator
C. Land
All nvallablo and pertinent data are onterod In the tibia; no entry Indicator that no data are
avn11ahlo.
• Personal conwunlcaHon bofnoon Oubra 0111 an! of AAN anil Pat Wood of Ver«ar, Itovembur 2, 1901.
t tenon at connuntcatlon betwoon Susan Ihomas of ACNP and Pat Nbod of Varsar, ftovembor 19, 1981.
Ftorsoivl commintcatlon bofwoon Dotty Larch of Rt and Pat Wood of Vorjar, Novonbor 17, 1901.
-------
insulation, ana agricultural uses (JRB 1982). About two-thirds of all
vermlcullte 1s used In the construction Industry for lightweight
aggregates and Insulation. The following uses of vermlcullte are
summarized from the materials balance (JRB 1982).
. Lightweight aggregates (JRB Mr) Lightweight aggregates
Include concrete aggregates, plaster aggregates, and aggregate premises
Hore than 95 percent of v*™1cul1te concrete Is batched and poured on
site from vermlcullte bagged and shipped from the exfoliating plant The
remaining 5 percent 1s batched In bulk at concrete premlx plants. About
2.5 percent of the vermlcullte concrete Industry consists of precast
products, mostly brick and block. i»
-------
a common Ingredient In lawn and garden fertilizers used by gardeners and
groundskeroers, landscapers. nurseryoea, and homeowners. About
three-fourths of these mixtures are formulated at the exfoliating plant.
VermlculHe 1s also commonly used In growing media. Half of the
vermlcullte so used 1s formulated by the distributor Into soil and
soilless premlxes; of this. 75 percent 1s shipped to greenhouses and the
rest retailed to the consumer. The other half Is bagged as 1s and
shipped from the exfollator to the distributor as "horticultural grade"
vernjlcullte. It 1s probably not rebagged. It 1s used mainly as a mulch
and son conditioner, for hydroponics, and for packing bulbs and seeds
for transportation. Of this horticultural grade sold. 50 percent 1s sold
to landscapers. 30 percent to greenhouses, 15 percent to nursery and
garden centers, and 5 percent to retell consumers (JRB 1982).
Vermlcullte has minor agricultural uses In livestock feed, hatchery
and poultry Utter, and seed encapsulation. Few persons are expected to
be exposed via these uses.
(4) Retail fJRB 19821. VermlcuUte has a number of consumer uses,
and may be offered for sale 1n virtually any kind of store that sells
merchandise for the home. It Is also used 1n window displays.
(5) Castable refractories and firebricks fJRB 1982). VermlcuUte
has refractory uses In aluminum and ferrous metal foundries as a
component of.moldlrg sands and Insulating cements and for other uses.
Vermlcullte-contaln'.ng firebricks are used 1n high temperature furnaces
and 1n other applications as listed 1n Table 17.
(6) Minor uses fJRB 1982). Unexfollated vermlcullte has a minor use
as a component of fire-resistant gypsua wallboard. Small amounts of
exfoliated vermlcullte are used as follows:
o As a filler and extender In paint, enamel, Ink, plastics, and
rubber.
o As flreprooflng In paper, fabrics, and plywood.
o As a filtration aid In wasteuater treatment, air purification In
uranium mines, and oil spill clean-up at shores and beaches.
o In oil well drilling muds.
o As an anti-splatter agent In welding.
o As artificial dust and fireplace ashes In the motion picture
Industry.
76
-------
7,2 Consumer Populations:
7.2.1 Attic Insulation
All loose-fill attic Insulation Is presumed to be Installed by
homeowners themselves (ORB 1982). However "• <*2«2trJll*SiSJ of
consumer exposure from this source. In order to estimate the number of
hous« containing such Insulation. 1t will be assu^d that vermlcullte
S« SM uSd Jnattlcs for ten years. Data from the Bureau of Mines
(1W - lS$ ndfcate Mil a total of 416.000 tons of loose-fill ^
llrnitrul He Insulation were produced 1n the nine-year period ending In
19M By extrapofauon, It Ly be assumed that 529 000 tons (WO mil ion
kg) have been produced In the past ten years. Ml ;°?«-["ynsuUtion
i! installed 1n attics (ORB 1982). If an average of 510 kg of
vemlcul te Is Installed per attic (ORB 1982). then about W>™*°™*
currently contain loose-fill verralcullte Insulation. Assuming that two
currently contan oose- .
pTr sons work at Stalling InsuUtlon 1n one attic then 188 000 persons
are so exposed per year. If the average American household Includes 2.13
JerVons (Bureau of the Census 1982). there are about 2.6 million people
living 1n dwellings containing vermlcullte attic Insulation.
The abov* figures are based on the assumption that vermlcallte
Insulation has been Installed only during the past ten years. It 1s
possible that the Insulation has been used for a longer period of time
but no confirmation was available.
7.2.2 Lawn and Garden Fertilizers
Market research (SMRB 1980) Indicate; that 33.8 percent of the U.S.
population buys lawn and garden fertilizers each year (74.4 million
persons based on 1980 population figures). The percentage of lawn
fertilizers containing vermlcullte Is not known. Ortho and O.H. Scott
are known to produce fertilizers containing verralcullte. Estech General
has reported that vermlcullte was removed from their Vlgoro product line
a few years ago (ORB 19'82). Approximately 32 million households kept
gardens 1n 1916 and 1917 (USEPA 1980b). !t may be assumed that
fertilizer Is used In all gardens, but again It 1s not known what
proportion of garden fertilizers contain verralcullte.
7.2.3 Houseplants
The number of Americans who own at least one hcuseplant Is not known
but probably Includes the vast majority of the population. The
percentage of houseplant potting soils that contain vermlcullte Is not '
known. The majority of houseplant owners probably buy plants that are
already potted and keep them Indefinitely without repotting. If the soil
does contain verralcullte. It Is probably kept fairly moist, 1s rarely (if
77
-------
ever) disturbed, and would therefore not
son, often using bagged horltcultural verralcu 1te Th?v J5?J
exposed to verm1cul1te during mixing and reDotti™ o2 y ?
cultivate succulents or i*o?rSS2tlJTU?5tt2« ™ iTL
vermlcullte. Market research (SHRB 198oT?ndiStIf tffi 46
people purchase house plant food or fert Hzer annual ?! TM.
considered an upper limit for exposure to pottiSg sills
7.2.4 Other Minor Uses
(1) Kitty Utter. Most litter box liners for house cats contain
c ay minerals; probably fewer than half contain vermlcu'lS! S!S ,5
million people own cats. SIX of whom use cat box filler fSMRa iSni
Assuming half cf those consumers buy the vermlcullte contfinfnl f ^ *
the total exposed population would be abou7?.8 Ini?S !? 9 product'
(2) Barbecue bases. Vermlcullte Is sold 1n bags to owners of horn*
barbecue grills. The vermlcullte 1s used to retain and rin«t JL5 .,
to absorb grease and drippings. There 1? no dlta on tSe nSer of
persons who barbecue outdoors. However, since barbecuing iflsSb
pastime and requires a certain minimum of yard space the bfrbecui
population is probably roughly comparable to the population^ I * S
who buy lawn and garden fertilizers. This is apparently takJn for
granted by the distributors of the product, who usual lyreSen^ th-t
the used, greasy vermlcullte be packed around shrubs as
7-3 populations Exposed to Asbestos-cont^inated w.nMr..n*a *n thp
Ambient Environment . ~ - • — tn-
Persons living near mines, mills, and exfoliation plants are exoosed
to asbestos fibers emitted from baghouses and other control devices Is
The four American vermlcullte mines are found at three sites- Libbw
Montana; Enoree. South Carolina (two mines): and Louisa Virginia The
estimated 1980 population of these three towns Is 4,680 persons (Bureau
of Census 1SS1), all of whom could experience a.nblent exposure to
asbestos fibers from mining and milling operation emissions.
70
-------
There are 52 exfoliation plants In 47 cities within the U.S. (JRB
1982). The Inhabitants of these cU1es are exposed to various levels of
asbestos fibers. St. Louis was chosen as a representatlva site and was
used In the ATH-SECPOP model (see Section 6.4.1) estimating ambient
exposure from exfoliation. In the ATM-SECPOP results, all persons within
50 km were exposed to seme asbestos. For the purposes of this exposure
assessment, 1t was not possible to count the populations within 50 km of
each site accurately. Instead. 1980 Census data (Bureau of Census 1981)
were obtained for most of the 47 cities. Table 18 lists these data. The
total number of persons amblently exposed to asbestos from vermlcyllte
exfoliation 1s estimated to be 13.U7.496. Section 8 will discuss the
level to which each subpopulatlon within that total 1s exposed.
The procedure used to estimate this population Is Halted, and the
figures obtained must be considered approximations. The limitations
Include:
• Data were unavailable for three sites: Beltsvllle MO; Kearney,
SC; and Enoree, SC. Haps Indicate that these are small towns. A
population of 1,000 was assumed for each.
• It was not possible, within the scope and resources of this study,
to determine the exfoliation plants' actual locations, to see
whether nearby towns might be affected.
• It was assumed that the total reported population within a town
would be exposed to some extent. ATM results Indicate that fibers
are dispersed to a 50 km radius, and 1t 1s unlikely that cny city
enumerated by the Census would exceed those bounds.
• It was assumed that asbestos Is present as a contaminant 1n the
vermlculUe processed at all of the exfoliation plants. Actually,
some vermlculHe Is not contaminated with asbestos.
It 1s not possible to determine the nutnber of persons exposed to
asbestos from vermlcullte transport or disposal; 1n many cases they would
be the same persons exposed via mining, raining, or exfoliation, since
disposal and transport would be localized around these Industrial sites.
Ho significant ambient exposure via water or land would be expected.
Section 5, summarizing the fate and transport of asbestos fibers and
exposure pathways, shows that water and land are not Important sources of
exposure to asbestos from vermlcullte.
79
-------
Table JB. Sftes of Exfoliation Plants and Populations Potentially Exposed
City
St. Louis. M0»
Cleveland. OH
Wntwapotts. w"
Beaver Falls. PA
Irondale. M.
Pnoenlx. AZ
N. Little Rock. AR
N««ark. CA
Santa Ana. CA
Denver. C0»
Po«par,o Beach. FL
J.*fc.o.»MI.. FL
T«.pa, FL«
West Chicago. IL
He-port, KY
Ne« Orleans. LA
Beltsvllle. H)
Easthampton. KA (Town. Hampshire Co,)
Deerforn. M,
OMha' NE
Trenton, NJ
Weedsport, NY (Village)
Hlch Point, *C
Oktaho»a City, OK
Porttand, OR
No. Castle PA
Kearney, SC
Travellersftest.SC
Kashvllle, TN (Nsshvll le-Oev Idsort )
San Anton, o, TX
Dallas. TX
HllwaiVee. Wl
Glrard. IL
Kenosha, Wl
Dek.lb, IL
Enoree, SC
Great Fal Is. MT
Mlnot, NO
Metuexen, NJ faorough)
Marysvllle, OH
Pine Bloff, AR
Honolulu, HI
Salt Lane City. UT
Houston, TX
WellsvlMe, KS^
Kansas City, <5
Louise. VA tTo.r?
1980 Population
olants opera-* within this city.
data .ere avaMab.e; , pcpu.atUn of . i.COO. Is
Sources:
. Bureau of C«ns«
453.085
573,822
57° 95'
12,525
6.521
764-9n
64.419
32.126
52,618
.
'•
««
'
3-017
2*246
t>ooob
32343
Ij'762
'
56576
762.974
163.033
1,504.086
, ' J6J
161^087
I3.U7.499
80
-------
8. INTEGRATED EXPOSURE ANALYSIS
This Integrated exposure analysis combines the estimation of
environmental concentrations with the Identification of locations and
habits of the exposed populations to yield exposure profiles. Section
8.1 Identifies the exposed populations, addresses the pathways leading to
exposure, and calculates Individual exposure for subpopulatlons.
Subsections w*.th1n 8.1 deal with each exposure scenario and with a
profile of 'worst plausible case* exposure. Section 8.2 Is a qualitative
assessment of the uncertainties and limitations Inherent In the exposure
analysis.
8.1 Exposure Profiles and Calculations
8.1.1 Occupational Exposure
Occupational exposure occurs during the mining and benef1dat1on,
exfoliation, transport, and use of vermlcuHte. The following sections
deal with each major step In the flow through commerce.
W Miners and Millers of Vermlcullte. Mining and beneflclatlon of
vermlcullte are performed at four sites employing a total of
approximately 500 persons. It 1s estimated that half of that total are
clerical, managerial, and administrative personnel not coming 1n frequent
contact with the processes and subsequent releases (Hunslcker and
Slttenfleld 1979). Actual production workers (or operatives) are exposed
to levels ranging from less than 0.01 to 9.7 f1bers/cc (see Table 11).
:able 19 displays the Inhalation exposure calculations for
asbestos-contaminated vermlcullte. As explained 1n Section 5.2.
Inhalation 1s assumed to be the only significant route of asbestos
exposure from vermlcullte. Mining and milling releases may lead to an
exposure level of as much as 9.7 f/cc In worker subpopulatlons. This
assumes that all fibers are resplrable; H has been shown that this Is
!"*'! ] 19t5h.bUt Hber $1ze data ^cessary to factor 1n the
fraction of fibers were not available.
. <2> Exfollators of Vermlcullte. Exfoliation of vermlcullte leads to
atmospheric emissions from process equipment and during handling
Uncontrolled emissions to the air wltMn an exfoliation plant may lead to
a
81
-------
(3) Transporters of Vgrmiculite. The number of perils Involved In
transportation of vermtculite 1s unknown; according to the National
Occupational Hazard Survey (NOUS 1980), 129 drivers and 108 rail workers
are exposed to asbestos from vermlculite transport (Table 19). It Is
probable that a large number of workers handling vermlcullte In transport
are unaccounted for.
Exposure during transport may be significant. Based upon personnel
samples taken at one mine, truck drivers may be exposed to 0.3 f/cc.
Rail workers are potentially exposed to high fiber counts resulting from
the transfer of beneflclated vermlcullte from railroad cars to
exfoliation facilities. Area samples have been taken In warehouses 1n
which workers handle .the exfoliated product. No asbestos was detected,
but 1t 1s likely that accidental spills occur with some regularity and
can lead to exposure during cleanup operations.
(4) Commercial and Industrial Users. This population includes
formulators of consumer products and users of exfoliated and unexfoliated
vermlculite. Few data are available to quantify asbestos exposures
within this group. Parts 1.0. and I.E. of Table 19 present the available
dat?. In some cases, product formulation data were combined with
exfoliation data and the same figures were used for both worker
subpopulations. This was the case for producers of lightweight
aggregates, verralculUe insulation, and agricultural and horticultural
products. •
Table 20 lists the occupational subpopulations for which no data were
available, and makes a qualitative statement of potential exposure.
8.1.2 Consumer Exposure
Consumer exposure has been calculated for three types of products:
vermlcullte loose-f'.ll attic insulation, lawn care products, and garden
fertilizer. The other consumer uses of verrolculite are not expected to
lead to high asbestos exposure, since population and releases are small.
/•n r™»»i«n»r-installation of Loose-fill Vermiculite Insulation. It
has been estimated that the attics in 940,000 homes have been Insulated
with vermlcullte in the last ten years (see Section 7.2.1). At the rate
of 94,000 homes per year, and assuming that the Job requires two people.
approximately 188,000 consumers are exposed each year.
Asbestos concentrations in an average attic are estimated in Section
6 4 The average exposure level is 6,800 vg/n)3 for the 8-fcour
period assuming that the vermlcullte contains 1 percent asbestos.
82
-------
Table 19. Summary of Inhalation Exposure to Asbestos In VermlculIt*
Population
Number of
persons
exposed3
Exposure
J«?velb
f/cc jjg/m3
Duration6
(hrs/*k>
Comments
do
•.*>
I. Occupational
A. Miners and mfilers
of vermlcullte ~ 230
B. Importers and unknown
oxport«.-s of
vermlculllo
C. Exfollators of 1.694-
vermlculfte 1,979
D. Usors of unex-
follatod vormleu lite
I. Stool workers 919
2, Hanu facturers of unknown
gypsum wall board
(a) Wholesale/ unknown
ret«; tradnrs
of gypsum wal 1-
boarcl
(b) Installors of
wal (board
unknown
fO-9.7
unknown
NC-0.38
unknown
unknown
unknown
unknown,
43.0
41.9
Number of persons
exposed estimated
as one-half total
employment.
-------
Table 19. (continued)
Population
Number of
persons
exposed8
exposure
levelb
Duration6
(hrs/wk)
Comments
E. Users of exfoliated
votm leu lite
1 .
Producers of
lightweight
aggregates
see I.e.
ND-0.38
41.5
Assure* that aggregates
produced at exfoliation
site* Bated upon most •
recent data.
Co
(a) Users of 34,659
. plasters, con-
cretes, and
aqgrotjstos con-
taining vormtcullto
-------
Table 19. (continued)
Number of Exposure
persons Ievc1b Duration*
Population exposed3 f/cc pg/m3 (hrs/wk) Comments
3. Producer* of agr I- unknown NO-0.38 41.6 Based on OSHA )9?9 and
cultural and hart I- HRJ 1982.
cultural products
containing vermleulite
J,136 unknown J2<7
cuttural/hortf-
cultural products
contain Ing verrol-
cullte
-------
Table 19. (continued)
Population
Numoer of fxposure
persons levelb
exposed* */cc pg/m3
Duration6
(hrs/wk)
Comments
(c) Producer* and
users of arti-
ficial dust
and drop loco
a she*
unknown
unknown
(d) Producers and unknown
users of refrac-
tories and fire-
bricks
unknown
(o) Producers and unknown
users of mls-
col leaoous
vwrmlcull te-
contatntng
products
5. Transporturs of
vormlcullto
(a) Truck drivers 129
(b) Ship and dock unknown
workers
(c) Rail workers 100
(d) Warohousomon unknown
II. Transportation and storage unknown
spills
unknown
-------
Table 19. (continued)
Of
"M
Population
1 It. Consumers
A. Hornoownors Intutatlng
attics with looso-Htl
vormtcullto
8. Usors of lawn and
garden fertilizers
(1) lawn application
(?) garden application
C. Users of huusoplant
pottfng soil with
vormlcullto
0. Usors of wrmlcullto-
bnsod kitty | Ittor
E. Users of vnrmlcultto
Number of Exposure
Persons |eve!b Duration0
exposed* f/cc Hg/m3 3000 unknown
unknown
<3, 600, 000
<74, 400,000 unknonn
Commant*
Tl^-w^^tod aver^a
conconlf al Ion est(nat«;
ow-'lnw 8-hr exixjsure.
r'n9-w«lghte<« average
concentration <*-tfnat«;
onc« yearly OK|-o«uras.
In barbecue grll Is
IV. Olsposfll
V. Food
VI. Drinking water
unknown
unknown
unknown
unknown
tin Known
unknown
-------
Table 19. (continued)
w
a>
Number ot .
persons
Population exposed*
VII. Ambient
A. Air
1. f'ersons near mines 4,680
end mil is
2. Person* nnor ex- 5>,905
foliation sites
111,734
305.022
1,513,27V
2,908,..26
3,038.386
4.403,036
7JJ.WO
Exposure
1eve)b OuraMon0
f/cc Jifl/m3
-------
co
to
Footnotes for Table 19
"Number of parsons exposed taken from Tab la 17 unless otherwise specified In "comments'* column.
Mo attempt was mado to convert units of asbestos measurement; units are as reported In primary fource. Monltorlrg data are
from Table II and modeling estimates are explained In Section 6.4.
cAmblent exposure duration was sot at 168 hours per wok; data do not warrant application of mobility patterns or other refine-
ments. Occupational exposure durations based upon overage work week for Industry sectors (BUS I960).
-------
Table 20. Occupational Suspopulatlons: Exposure Potential
Population
Potential for exposure
Importers and exporters
of vermlccllte
Manufacturers and osers of
gypsum wal(board
Users of lightweight
aggregates
Producers and users of
minor products
Users of.block-fill
Insulation
Wholesale/retail traders
of vermtcullre products
Exposure may be comparable to levels
encountered by transportation workers.
Uses unexfo Hated vemlcullte. Fabrica-
tion steps and Installatlon nay have
atioospherfc emissions and resultant
exposure.
Exposufs may occur during dry mixing; If
outdoors, fibers will be diluted.
Exposure Is highly product-specific;
high exposure with artificial dusts;
low exposure expected from refractories,
drilling nuds. filters.
Workers filling blocks nay be exposed to
high levels of asbestos.
Exposure Is product-specific; most
products are bagged or otherwise bound.
Exposure Is unlikely to be significant.
90
-------
w ^ Consumer Use of Garri»n Fertni7»r As seen In SPOH™ f. A
(3) Consumer Use of Lawn Car» P™^,.*, Th». Uftr_. ,.a
8.1.3 Ambient Exposure
exposure media (see Secion slz
nit. 1
exposed to asbestos fibers from Control 12 a H n?5' A11 are
Monitoring data collected at wiStJ I?m,S ? ""controlled emissions.
"" m
e a wit m, .
levels of asbestos rage f? S!drt.rt!S ^"l"?*?? m11ls 1nd1cate that
resident could be exposed to tMs leSef 21 hS f1be"/cc- A full-time
fraction of this level has not been deJemm^ 5erAy; The r«P^able
available to characterize '
91
-------
exposure near exfoliation sites. Bureau of Census (1981) data were used
to estimate the total population affected.
ATM-SECPOP calculates levels and counts persons within a 50 km radius
of a point socrct. As stated 1n the Populations section, enumeration of
populations 1s more ac:urate with a 15 km radius, so the ATM data were
reduced to the 15 km level. An exposure distribution was prepared from
the St. Louis ATM-SECPOP output. This exposure distribution was then
applied to the total U.S. population near exfoliation facilities to yield
the Information presented 1n Table 19.
As In the previous ambient exposure exar^ple. 1t was assumed that
exposure was continuous. A maximum exposure level of J.025 ng/ro3 was
calculated. It should be noted that St. Louis SECPOP data Indicate that
there were residences within 1 km of the site and that exposure to those
Individuals was high. Other exfoliation sites may be farther removed
from residential areas, although they are g1ve;i dty addresses. Exposure
estimates may therefore be somewhat biased tcward the higher end, but
these calculations present a plausible worst-cese situation.
8.1.4 Other Exposure Scenarios
Some exposure to asbestos associated with verrolculUe occurs through
the other exposure scenarios, but 1t 1s expected to be low In comparison
to the three scenarios discussed above.
Spills from transporatlon and storage are negligible, although there
are dust losses during loading and unloading of trucks, rallroao cars,
and barges (JRB 1982). Exposure to the general population to asi»estos
from loading and unloading 1s probably very small because of the
relatively low release rates; exposure to the transportation worker*
during loading and unloading 1s considered to be an occupational exposure
and 1s discussed 1n Section 8.1.1 above.
Disposal scenarios relevant to vermlculUe Include landfllllng cf
solid wastes from mining, benefidatlon, exfoliation, and processing;
discarded end products may also be landfllled (JRB 1982). Releases of
vermlculUe and asbestos from landfills are thought to be negligible.
Wastewater from mining, benef1dat1on, and exfoliation Is recycled, and
only minor amounts of vermlcullte and asbestos are released from water
treatment operations -at permanent vermlcuUte concrete plants (JRB
1982). Because water 1s not thought to be a significant exposure medium
for asbestos from vermlcullte, and because the aqueous releases of
vermlcullte and asbestos are Insignificant compared to air releases
covered In the occupational, consumer, and ambient scenarios, this
exposure pathway Is considered to be negligible.
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As discussed in Section 5.2.2. asbestos Is not expected to be
bloaccumulated; therefore, food Is not considered to be an applicable
exposure scenario.
Drinking water could contain asbestos from waterborne releases from
vermlcullte processing and use. Releases to water from all sources are
considered to be negligible (JRB 1982). Fe.te processes do, however,
result In some Intermedia transfer of asbestos from the atmospheric and
land environments to surface water. The available data are Inadequate to
support a quantitative estimate of exposure from Ingsstlon of drinking
water, but 1t 1s considered unlikely that this exposure route 1s
significant compared to the occupational, consumer, or ambient exposures
discussed above.
8.1.5 Integrated Worst-case Exposure Scenario
The geographic distribution of vermlcullte point sources and the
widespread use of some vermlcullte products Indicate that Individual
exposure may cotne from numerous sources. This facilitates the creation
of a plausible worst-case scenario, with a summation of exposure from
occupation, consumer products, and contaminated ambient air.
Unfortunately, asbestos data are reported In different units that cannot
be valldly compared.
The "worst-case* Individual's exposure sources and concentrations are
listed 1n Table 21; no attempt Is made to sum these Inhalation exposures,
although relative contributions from different sources are apparent.
The Individual works In an exfoliation plant, and lives In the dty
where the plant 1s located. He uses vernlculate-basert lawn and garden
fertilizers, and has Insulated his attic with loose-fill vermlcuHte.
8.2 Uncertainty of Analysis
Assumptions and limitations to the dita are discussed In detail
throughout the report. Major limitations are listed below:
• The validity of the monitoring data 1s unclear. Different
analytical techniques used by the EPA contractors may have
affected the results reported 1n Section 6 by as much as an order
of magnitude. OSHA monitoring data cannot be adequately analyzed
because Information on analytical techniques Is lacking.
• The results of ATM-SECPOP are based on numerous assumptions 1n the
Input data. Extrapolation of those results to all exfoliation
sites provides a crude approximation of exposure. The consumer
exposure models are also based on assunptlons and are clearly
designed to be worst-case exposure analyses.
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Table 21. Hbrst-dse Individual Exposure Level Profile
Source of exposure
Exposure level8
Working In an exfoliation
plant 2,000 hours yearly
Living In city with exfoliation
plant 3,736 hours yearly
fertilizing garden once yearly
for one hour
fertilizing lawn once yearly
for four hours
Insulating attic for 8 hours
once In lifetime
0.38 flbers/ce
0.025 Ug/.s
28
4.4 tig/nr5
6,800 Ug/m
8 Exposure levels from Table .19.
94
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• Population data were sparse; data for all populations are
estimates.
• There are no data on asbestos fiber size distributions In air
contaminated with veririlcullte releases. Exposure calculations are
therefore based on total fibers rather than on the resplrable
fraction. Similarly, 1t was assumed throughout the exposure
assessment that all verm1cul1te 1s contaminated by asbestos,
although some vermlcullte Is not. The three consumer exposure
scenarios all assumed that vermlcullte 1s contaminated with 1
percent asbestos.
Despite these limitations, this exposure assessment provides the best
data and predictions available. Further study would enhance the
usefulness of the data for regulatory declslonnaklng.
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9. REFERENCES
Bassett WA. 1959. The origin of the verm1cul1te deposit at L1bby,
Montana. Amer. Miner. 44:282-297.
Boettcher AL. 1966. Vermlcullte. hydroblotHe, snd blotHe 1n the Rainy
Creek Igneous Complex near L1bby, Montana. Clay Minerals. 6:283-296.
Bureau of the Census. 1980. Statistical abstract of the United States.
Washington. DC: U.S. Department of Commerce.
Bureau of the Census. 1981. Advance reports, population and housing, of
the 1980 Census. Washington. DC: U.S. Department of Commerce.
Bureau of the Census. 1982. Census of population. U.S. summary.
General population characteristics. PC80-1-B series. Washington, DC:
U.S. Department of Commerce.
Bureau of Labor Statistics. 1980. Handbook of labor statistics.
Washington, DC: U.S. Department of Labor. Bulletin 2070.
Bureau of Mines. 1973-1980. Vermlcullte. Preprint from the Bureau of
Mines minerals yearbook. Washington, DC: U.S. Department of the
Interior.
Burllkov T, Mlchallova L. 1970. Asbestos content of the soil and
endemic pleural astestosls. Environ. Res. 3:443-451.
Callahan HA, Sllmak MW, Gabel NW, et al. 1979. Water-related
environmental fate of 129 priority pollutants. Chapter 7. Asbestos.
Washington, DC: U.S. Environmental Protection Agency.
Chase RRP. 1979. Settling behavior of natural aquatic partlculates.
Llmnol. Oceanog. 24(3):417-426.
Chatfleld EJ. Lewis GM. 1979. Examination of Vermlcullte for the
presence of asbestos fibers. Mlsslssauga, Ontario: Ontario Research
Foundation. Report number 22056-2.
Choi I, Smith RW. 1972. Kinetic study of dissolution of asbestos fibers
In waters. J. Colloid Interface Sd. 40(2):253-262.
Chowdhury S. 1975. Kinetics of leaching of asbestos minerals at body
temperatures. J. Appl. Chem. Blotechnol. 2b:347-3S3.
Chowdhury S, Kitchener JA. 1975. The *eta potentials of natural and
synthetic chrysotlle. Internat. J. Mineral Processing. 2:277-285.
97
-------
Cook PM. 1973. Distribution of taconlte tailings 1n Lake Superior water
and public water supplies. Duluth, Minnesota, USEPA National Water.
Quality Laboratory. .Second progress report, July 1973.
Culkowskl WM, Patterson MR. 1976. A comprehensive atmospheric transport
and diffusion model. Oak Ridge, Tennessee: Oak Ridge National
Laboratory. ORNL/NSF/EATC-17.
Deer UA, Howie RA, Zussman 3. 1962. Rockformlng Minerals Vol. 3. Sheet
Silicates, pp. 246-257.
Dement OH, Harris RL. 1979. Estimate of pulmonary and gastrointestinal
deposition for occupational fiber exposures. Washington. OC: U.S.
Department of Health, Education and Welfare (NIOSH) Publication No.
79-135.
EIS. 1980. Economic'Information Service. Computer printout:
employment 1n vermlcultte Industry.
Encyclopedia of Associations. 1981. Detroit, Michigan: Gale Research
Co.
Feely RA. 1976. Evidence for aggregate formation in a nephelold layer
and Us possible role 1n the sedimentation of partlculate matter. Marine
Geol. 20:7-13.
GCA. 1980. Vermlcullte regulatory options analysis. Bedford, MA: 6CA
Technology Division.
Gooch ED. 1957. Verm1cul1te. Virginia Minerals 3(l):l-6.
6runer JW. 1934. The structures of vermlcuUte and their collapse by
dehydration. Amer, Miner. 19:557-575.
Haagen-Smlt AJ, Wayne LG. 1976. Atmospheric reactions and scavenging
processes. In: Stern AC, ed. Air pollutants, their transformation, and
transport. New York: Academic Press.
Harwood CF, Ase PK. 1977. Field testing of emission controls for
asbestos manufacturing waste piles. . II.TRI, Cincinnati, Ohio: U.S.
Environmental Protection Agency.
Harwood CF, Blaszak TP. 1974. Characterization and control of asbestos
emissions from open sources. IITRI. Washington, DC: U.S. Environmental
Protection Agency, PB 238-920.
Hews OP. EH. 1976. Meteorological measurements. In: Stern Ac, ed. Air
pollutants, their transformation, and transport. New York: Academic
Press.
98
-------
Hodgson AA. 1979. Chemistry and physics of asbestos. In: Hlchaelo I,
Chlsslck SS. Asbestos. Vol. 1 - properties, applications, and hazards.
New York: John Wiley and Sons.
Kostetler PB. Christ CU 1968. Studies 1n the system
HgO-S102-C02-H20(I): The activity product constant of chrysotlle.
6eoch1m. Cosraochlra. Acta. 32:485-497.
Hunslcker S, SUtenfleld H. 1979. Occupational hazards of vermlcullte.
Philadelphia, PA: Calculon. EPA Contract No. 68-01-3899.
Hunter CE. 1950. Vermlcullte of the Southeastern states. In: Sayder
FG ed. Symposium on mineral resources of the Southern United States.
KnoxvWe, Tennessee: The University of Tennessee Press.
JRB 1982 Interim draft final. Level II materials balance -
vermlcullte. Washington, DC: U.S. Environmental Protection Agency.
Kramer JR. 1976. Fibrous cummlngtonlte In Lake Superior. Can. Mineral.
14:91-98.
Kreston P, Berggren S. 1978. The thermal decomposition of vermlcullte.
Thermoch1m1ca Acta. 23:171-182.
S:
York: Academic Press
1. f
Wash!ngtoS' DC? U?S? Environmental Protection Agency. Contract No.
68-01-5S15.
Myers JB. I960. Vermlcullte. In: Industrial Minerals and Rocks, 3rd
ed. New York: AIHE. .
99
-------
Naimann AW, Presher MM. 1968. Colloidal suspensions of chrysotlle
erhancement' J' Col1o1d interface Set.
.TJJSr* Char9e of Part1cu1ate matter 1n
8- JSid SfBlS 0r;?ter and the
Nat1ona1 Occupational Hazard Survey. Computer
P
oce«pat1on. itertlt. DC-
for Occupational Safety and Health.
ln
PCJCO Environmental Specialist! Inc. 1973. Investigation of
"ntro1- 0
Petrov yp. 1962. Perllte and vermlcuUte (geology
IS
Ralston 0. Kitchener JA. 1975. The surface chemistry of amosUe
^llcate. J. Colloid Interfax Sc?
. 197?. The living plant. New York: Holt. Rlnehart and Winston
• --- Sprayed asbestos-containing materials 1n
?mec??.n-«ae?^an!^4lS^toH:"""10"- "' U'S- E""«t"
100
-------
Schroitt P.P. Unsten DC, Shannon TF. 1977. Decontaminating Lake Superior
of asbestos fibers. Environ. Sc1. Technol. 11(5}:462-J65.
Scow K, Wechsler AE. Stevens J. Wood H. Callahan HA. 1979.
Identification and evaluation of waterborne routes of exposure from other
than food and drinking water. Washington, DC: U.S. environmental
Protection Agency.
Sebastlen P, Billon MA, Oufour 6, Gaudlchet A. Bonnaud G. 1979. Levels
of asbestos air pollution 1n some environmental situations. In:
Seltkoff IJ, Hammond EC, eds. Health hazards of asbestos exposure.
Annals of the New York Academy of Science. 330:401-415.
Smith GR, Carpenter LM, Stanley RL, Nuelle- PIC. 1973. Determination of
the concentration cf asbestos fibers 1n ambient air near a.i asbestos
processing plant. Berkeley, CA: Air and Industry Hygiene Laboratory.
SMR8. 1980. Simmon Market Research Bureau Inc. The 1980 tudy cf media
and markets. New York: Simmons Market Research Bureau, Inc.
Spell S, Lelneweber JP. 1969. Asbestos minerals In modern technology.
Environ. Res. 2:166-208.
Stern AC, ed. 1976. A1r pollution. Vol. I. New York: Academic Press.
Sverdrup HV, Johnson WM, Fleming RH. 1964. The oceans, their physics,
chemistry and general biology. Englewood Cliffs, New Jersey:
Prentke-Hall.
Timbrel! V. 1965. The Inhalation of fH'-ous dust. Annals N.Y. Acsd.
Sd. 255-273.
Turner DB. 1969. Workbook of atmcspher': dispersion estimates.
Cincinnati. OH: U.S. Department of Heaitfi. Education, and Welfare.
Public Health Service. PUS pub. no. 99S-AP-26.
USEPA. 1974. U.S. Environmental Protection Agency. Background
Information on rational emission standards for hazardous oollutants -
proposed amendments to standards for asbestos snd mercury. Washington,
DC: EPA-450/2-74-009a.
USEPA. 1980a. U.S. Environmental Protection Agency. Priority review
level 1 - asbestos-contaminated vermlcullte. Washington, DC: U.S.
Environmental Protection Agency.
USEPA. 1980b. U.S. Environmental Protection Agency. Dietary
consumption distributions of selected food groups for the U.S.
population. Washington, DC: U.S. Environmental Protection Agency. EPA
560/11-80-012.
101
-------
Wanta RC, Lowry WP. 1976. The meteorological setting for dispersal of
air pollutants. In: Stern AC, ed. Air pollutants, their transfjrmatIon
and transport. New York: Academic Press.
Whelpdale DH, Hunn RE. 1976. Global sources, sinks, and transport of
air pollutants. In: Stern AC. ed. A1r pollutants, their transformation
and transport. New York: Academic Press.
Williamson SJ. 1973. Fundamentals of air pollution. Addlslon-Wesley.
102
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