v>EPA
United States
Environmental Protection
Agency
Health Effects Research
Laboratory
Research Triangle Park NC 2771 1
Research and Development
EPA-600/S1-81-042 July 1981
Project Summary
Determinants of Cancer and
Cardiovascular Disease
Mortality in Mining
Counties of California
R. A. Ziskind, D. F. Smith, J. L. Hahn, and G. Spivey
The purpose of this research effort
was to design an epidemiological
study protocol to evaluate the influence
of environmental asbestos exposure
on mortality from lung cancer, meso-
thelioma, and cardiovascular disease
in the asbestos mining areas of Cali-
fornia. Mortality data (1968-1978)
and emissions data (both anthropo-
genic) were reviewed in an effort to
determine the most preferable study
area. The area selected for future
study was Western Calaveras and
Tuolumne Counties which contain the
Calaveras serpentine deposit. Selec-
tion criteria included suitable popula-
tion base, sufficient number of deaths,
evidence of elevated airborne and
waterborne asbestos concentrations,
and the existence of archives contain-
ing ambient air sampler filters for
preceding years. A questionnaire was
developed for obtaining information
from next-of-kin of decedents in the
study area though interviewing was
not attempted. Next-of-kin interviews
are expected to be a component of
future studies. Necessary elements of
quality assurance were identified and
documented as part of protocol design.
This Project Summary was devel-
oped by EPA's Health Effects Research
Laboratory, Research Triangle Park,
NC, to announce key findings of the
research project that is fully docu-
mented in a separate report of the
same title (see Project Report ordering
information at back).
Introduction
This epidemiological study evaluates
the hypothesis that asbestos-related
health effects have been observed
among populations not occupationally
exposed. The study was divided into four
conceptual tasks:
Epidemiological protocol design. I n
this segment, alternative study ap-
proaches were evaluated. The mortality
data base, the sources, and the exposure
to asbestos were considered.
Questionnaire development. In con-
cert with protocol design and exposure
findings, the primary data-gathering
mechanism for obtaining subject infor-
mation from survivors was drafted, pre-
tested, revised, and submitted.
Source inventory and exposure char-
acterization. All anthropogenic and
natural emission sources of asbestos
were delineated and quantified in each
California study area. Existing occupa-
tional and ambient data were reviewed
to establish inhalation and ingestion
population exposure.
Quality assurance. Elements of qual-
ity assurance were to be identified and
documented as part of the protocol
design.
The initial components of this study
were the source inventory and exposure
characterization. A summary of the
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principal findings are given here.
Two distinct California asbestos min-
ing and milling areas were researched.
One is associated with a serpentine
deposit running through the junction of
Fresno and San Benito Counties (herein
referred to as the New Idria Deposit).
The second is located throughout the
western sections of Calaveras and
Tuolumne Counties (the Calaveras De-
posit). The preferable study area was
determined to be that associated with
the Calaveras Deposit. Selection criteria
included greatest population base, evi-
dence of elevated airborne and water-
borne concentrations of asbestos, and
the existence of archives of useful
ambient air sampler filters dating back
over seven years.
For the case of the New Idria Deposit,
the mining areas are sufficiently remote
to make it unlikely that any population
center will be affected. One mill is
located near a community and limited
airborne asbestos measurements point
to significant concentrations there at
the time taken.
By contrast, the Calaveras Deposit
area has a greater at-risk population as
a result of mining and milling of asbestos
and other minerals. In addition, airborne
background ambient levels taken up-
wind or remote from known sources are
elevated. No waterborne asbestos mea-
surements were made specifically for
the water distribution systems serving
the Calaveras Deposit area; however,
measurements on San Francisco Bay
water district reservoirs located in
western CalaverasandTuolumne Coun-
ties show higher than average concen-
trations for those with supplies passing
through serpentine formations. The
oldest ambient data uncovered for the
Calaveras Deposit area was reported in
the California Department of Health
Study of 1965-1967. Asbestos concen-
tration was measured by dust sample
collection through impingers. Quantifi-
cation was by optical microscopy. Mea-
sured ambient levels (upwind at a large
mine site, etc.) on two separate occa-
sions ranged between 0.1 and 2 million
particles per cubic foot of air. A federal
study at about the same time of the area
"Environmental Survey of Asbestos
Mining and Milling in California" De-
cember, 1966, Public Health Service
Division of Occupational Health, suggests
the equivalence 10 total fibers/cc = 1
mppcf by impinger. In the cited ambient
concentrations (from the NIOSH Rec-
ommended Asbestos Standards), the
levels across the country are summar-
ized as generally < 10 ng/m3 with
occasional peaks as high as 100 ng/m3
(by electron microscopy). Using optical
microscopy, ambient levels are generally
less than 0.01 fibers > 5 fjm/cc with
peak values as high as 0.03 fibers > 5
fjm/cc. Use of the Public Health Service
equivalence 6 fibers > 5 /um/cc = 1
mmpcf by impinger yields the mine area
ambient (upwind) concentration range
0.6-12 fibers/cc.* Further, use of the
NIOSH suggested equivalent 20 fibers
> 5 fjm in length (as determined by
optical microscopy) per nanogram of
asbestos yields the mine ambient range
12-240 ng/m3. Thus, the ambient levels
detected at upwind locations in the
vicinity of a Calaveras mine/mill are at
the extreme high end of the surveyed
range.
High volume air sampler filters from
the Calaveras Deposit area population
centers have been located in the Cali-
fornia Air Resources Board archives
dating back to the early 1970s. They can
be utilized to quantify airborne asbestos
concentration and they therefore ap-
proximate exposure data. Coupled with
the water assay, they will establish the
quantitative relationship among popu-
lation centers in the serpentine area
and the other areas of Calaveras and
Tuolumne Counties. Also, they will
provide the basis for stratifying the
populations according to inhalation and
ingestion exposure.
Based upon the source and exposure
information available to this study, the
potential study group was defined as
those people who died in Calaveras and
Tuolumne Counties during the last ten
years. Approximately 4,300 people will
be included. Exposure of the prelim-
inarily identified group is expected to be
significant; principally due to general
ambient sources rather than a dominant
single point source. Exposure may be
differentiated among the group members
between air and water, with either
predominating in particular residential
segments. This approach will permit
investigation of the relative importance
of different exposure routes and will
facilitate interpretation of possible
dose-effect relationships. Water distri-
bution systems for the area through the
last ten years were described.
•Note: The current NIOSH recommended standard
is 0-1 fiber/cc for an 8-hour time-weighted
average.
Conclusions
There are two principal areas of
California in which asbestos mining and
milling activities are conducted. This
study investigated both areas and sur-
veyed the anthropogenic and natural
sources of asbestos emissions into the
environment. The county areas which
constitute both regions are principally
rural; the cities generally contain less
than 6,000 people. The only large cities
in Calaveras, Fresno, Monterey, San
Benito, and Tuolumne Counties are
located apart from the serpentine areas.
The coincidence of asbestos mining and
milling with such less-urbanized county
areas is a favorable factor; people in
more populous urban centers are ex-
posed to a number of toxic substances in
their ambient environment.
Based upon the synthesis of published
literature, a field survey, and the review
of the limited asbestos monitoring infor-
mation available, the study concluded
that airborne and waterborne asbestos
levels in particular areas of Calaveras
and Tuolumne Counties may be elevated
with respect to background. In the other
principal serpentine area (San Benito,
Fresno, Monterey), insufficient infor-
mation is available to estimate exposure.
In these latter areas, mining activities
are relatively isolated from population
areas. However, ore transport and
milling are in the King City-San Lucas
areas. Isolated airborne data taken in
King City showed elevated concentra-
tions; more extensive mill site data
(provided by the mill management)
appears somewhat lower. The single
piece of waterborne assay information
from the Coalinga vicinity is insufficiently
documented to be definitive.
Upwind data taken at Calaveras as-
bestos during 1965-1967 range from
12-240 ng/m3 extrapolated to electron
microscope concentrations from optical
microscopy counts of fibers greater than
5 fim. Ambient concentrations across
the country are generally below 10
ng/m3.
High volume air quality sampler filters
were located in the archives of the
California Air Resources Board for a
number of sites in Calaveras and
Tuolumne Counties. Samples of 24- and
48-hour duration date back to the early
1970s. These asbestos analyses are
practical and may be utilized to provide
an exposure mapping of the areas of inter
est.
Water distribution systems in Cala-
veras and Tuolumne Counties have
been identified. Sources, routes, and
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.reatment differ throughout the area. No
specific asbestos analyses of the water
used for local supply was found. Based
upon several available measurements
of elevated asbestos content in serpen-
tine deposit area reservoirs (which
serve San Francisco Bay communities),
water sampling and analysis should be
performed for chrysotile asbestos.
Based upon available air and water
data, elevated asbestos exposure to the
general population may have occurred
in areas of Calaveras and Tuolumne
Counties.
Recommendations
Water sampling and air/water anal-
ysis should be conducted to define ex-
posure to the population by place of
residence. Parallel with that effort,
information from the California death
tape rolls can be initially extracted on an
annual basis for both counties. These
tapes can be processed according to
cause of death (ICD system) with case
and control groups extracted, and dis-
ease mortality rates compiled. The
statistical adequacy of all cause-of-
death categories of interest would then
be determined. All diseases associated
with occupational exposure to asbestos
vould be considered. In addition, all
statistically adequate death category
populations can be contrasted as a
function of exposure. The product of this
effort is the delineation of the range of
correlation of mortality categories with
exposure. This may suggest additional
cause-of-death categories. These steps
will be followed by the final study
components which will include the
detailed data gathering by survivor
questionnaire and medical records and
the comprehensive data analyses.
/?. A. Ziskind, D. F. Smith, J. L Hahn, and G. Spivey are with Science Applica-
tions, Inc., Los Angeles, CA 9O067.
John Acquavella is the EPA Project Officer (see below).
The complete report, entitled "Determinants of Cancer and Cardiovascular
Disease Mortality in Asbestos Mining Counties of California," (Order No.
PB 81-208 985; Cost: $11.00, subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Health Effects Research Laboratory
U.S. Environmental Protect/on Agency
Research Triangle Park, NC 27711
> U.3. QOVERNMEHT PRINTtNO OFFICE 1W1 -757-012/7Z11
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