vvEPA
                                United States
                                Environmental Protection
                                Agency
                                 Environmental Monitoring Systems
                                 Laboratory
                                 Research Triangle Park NC 27711
                                 Research and Development
                                 EPA-600/S4-82-021  May 1982
Project  Summary
                                Bulk Sample  Analysis for
                                Asbestos  Content:
                                Evaluation  of the Tentative
                                Method

                                E. P. Brantly, Jr., K. W. Gold, L E. Myers, and D. E. Lentzen
                                  The U.S. Environmental Protection
                                Agency Office of Pesticides and Toxic
                                Substances, Washington, DC, and the
                                USEPA Environmental Monitoring
                                Systems Laboratory, Research Trian-
                                gle  Park, NC, jointly sponsored an
                                effort to produce a practical  and
                                objective analytical protocol for the
                                qualitative and quantitative analysis of
                                asbestos in bulk materials. Draft pro-
                                cedures were written for analysis of
                                bulk samples by polarized light micros-
                                copy (PLM) and X-ray powder diffrac-
                                tion (XRD). Following review, the
                                Tentative Method for the Determina-
                                tion of Asbestiform Minerals in Bulk
                                Insulation Samples (March 1980) was
                                submitted to a performance testing
                                program that involved multiple labora-
                                tory analysis of prepared samples with
                                known asbestos content. This report
                                presents  the results of the testing
                                study and provides preliminary obser-
                                vations and characterization of the
                                utility and operational, parameters of
                                the tentative Method.
                                  PLM quantitative analysis employs a
                                point counting procedure to estimate
                                the relative area occupied by asbestos
                                fiber within the microscope fields of
                                view. PLM data must be compared
                                with the known weight of asbestos in
                                the sample in order to characterize the
                                accuracy  of the method, Data pro-
                                duced by the point counting procedure
                                are  also compared with those pro-
                                 duced by the typical quantisation pro-
                                 cedures used by some of the partici-
                                 pating laboratories.  Accuracy and
                                 precision of the point counting pro-
                                 cedure are considered in two contexts:
                                 (1) as PLM is currently used, regarding
                                 reported data as a direct estimate of
                                 weight percent of asbestos  present
                                 and (2) allowing adjustments of the
                                 data to account for bias and variance
                                 in the relationship between the relative
                                 area occupied by  asbestos and  the
                                 known weight percent of asbestos in
                                 the sample. Information is also pre-
                                 sented on within-laboratory variance
                                 and the frequency of  false negatives
                                 and false positives.
                                  A very limited amount of data was
                                 returned for characterizing the XRD
                                 protocol. Both  thin-layer and thick-
                                 layer (bulk)  techniques were used for
                                 quantitative XRD analysis. Because of
                                 the small number of XRD reports and
                                 the nonequivalence of methods em-
                                 ployed, it is not possible to draw any
                                 firm conclusions on the precision and
                                 accuracy of the  XRD protocol. A
                                 general comparison of bulk and thin-
                                 layer techniques with  respect to pre-
                                 cision, accuracy, and sensitivity is
                                 made.
                                  This Project Summary was develop-
                                 ed by EPA's Environmental Monitoring
                                 Systems Laboratory, Research Trian-
                                 gle Park, NC, to announce key findings
                                 of the research project that  is fully

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 documented in a separate report of the
 same title (see Project Report ordering
 information at back).

 Introduction
   An interlaboratory study was conduc-
 ted to evaluate the accuracy, precision,
 and  general  utility of the Tentative
 Method forthe Determination of Asbes-
 tiform  Minerals in  Bulk  Insulation
 Samples (March 1980). Twenty-two
 commercial and four government labora-
 tories  were each  supplied with 11
 samples. Eight  of the  samples were
-formulated with a known  weight  of
 amosite  or chrysotile and a matrix
 material containing primarily gypsum.
 Within-laboratory duplicates, blanks,
 and "real-worjd" samples  of sprayed
 insulation were also included  in the
 materials distributed to laboratories. Four
 laboratories (two commercial, two gov-
 ernment) chose not to participate in the
 study. Th#22 participating laboratories
 provided  a  total of 30  polarized  light
 microscopy (PLM) reports and six X-ray
 powder diffraction (XRD) reports.
   The Tentative Method includes proce-
 dures for qualitative  and quantitative
 analysis of bulk samples by PLM and
 XRD. Identification of asbestos fibers by
 PLM  requires the  observation of six
 optical properties:_morphology, color and
 pleochroism, refractive indices (or dis-
 persion staining colors), birefringence,
 extinction characteristics, and sign  of
 elongation. PLM quantitative analysis
 uses a point counting procedure to
 estimate the percent area occupied by
 asbestos  fiber within the  microscope
 fields of view. The prepared samples
 distributed  in this  study contained  a
 known  weight  percent of asbestos.
 Because PLM analysis produces an
 estimate of the relative area occupied by
 asbestos, the relationship between re-
 ported  area percent  and the known
 weight  percent of asbestos was investi-
 gated.
   Identification of sample components
 by XRD analysis is accomplished by
 comparison of the  sample  diffraction
 pattern with standard reference powder
 diffraction patterns. Quantitative anal-
 ysis involves measuring the integrated
 areas of diagnostic peaks selected from
 the full  XRD scan of a thin-layer sample.
 Quantitative analysis must include  a
 correction for matrix absorption effects
 and comparison with  suitable external
 standards. XRD affords information only
 on crystal lattice structure  and  not on
 crystal morphology. XRD analysis, there-
fore, cannot distinguish between asbes-
tos minerals and their nonasbestiform
varieties. The presence of fibrous parti-
cles in a sample must be determined by
an optical technique such as PLM.

Conclusions
  Linear regression in natural logarith-
mic coordinates was used to study the
relation between the reported data, in
terms of percent asbestos by area, and
the known values, in terms of percent
asbestos by weight.  The  fact that'a
considerable amount of the variation in
the data was removed by regression in
logarithmic coordinates is  consistent
with the assumption that area percent
and  weight percent are related toy  a
power function. Analysis of the regres-
sion shows that variation in the area-
weight  relationship is attributable to
differences between laboratories, differ-
ences between asbestos types (chryso-
tile and amosite), and interactions
between laboratory and asbestos type.
  Reported PLM data were divided into
three groups based on the quantitation
procedure(s) used by the reporting labor-
atory.

    Group P(Point count) PLM asbes-
             tos area percent determi-
             nations by the point count
              procedure (Tentative
         '.    Method).
    Group B(Both) PLM asbestos area
              percent determinations
              by the laboratories' own
              methods for laboratories
              that also provided data
               by the  point count
              method.
    Group  O(Other) PLM  asbestos
              area percent determina-
             tions by the laboratories'
              own methods for labora-
              tories declining to use
              the point count method.

  Considering  reported PLM results as
direct esti mates of the weight percent of
asbestos (i.e.,  ignoring the problem of
relating area percent  and weight per-
cent), it was found that Group  O is
significantly more biased than Group P.
Groups P and B are similarly biased.
Point counting has a  greater positive
bias on amosite samples than on chryso-
tile samples. For a sample containing 10
percent chrysotile by weight, the aver-
age bias (b) of Group P is 18.5 percent;
for  50 percent chrysotile, b = -24.2
percent; for 10 percent amosite, b  =
 118.5 percent; for 50 percent amosite, b
 = 12.1 percent.
  A regression relating standard devia-
 tions and means of reported PLM results,
 when performed'in  natural logarithmic
 coordinates, did not establish any differ-
 ences among Groups P, B, and O with
 respect to precision. The standard devi-
 ation of Group P is directly related to the
 mean reported value. Precision may be
 expressed as the coefficient of variation
 (CV). The CV is less than 100 percent on
 samples containing  more than approxi-
 mately 6 percent asbestos by area, and
 less than 50 percent on  samples con-
 taining  more  than  approximately  32
 percent asbestos by area. At a mean
 reported value (MP) of 10 percent asbes-
 tos, CV & 79 percent; at M P = 20 percent,
 CVs61 percent; at MP = 50 percent, CV
 s=41 percent.
  Analyses were performed on trans-
 formed  data to investigate improve-
 ments in data quality that might  be
 made by adjusting (calibrating) individ-
 ual laboratory results. If the parameters
 of the area-weight relationship are used
 to transform reported area percent data
 to predicted  weights,  a  considerable
 gain in accuracy is achieved, as meas-
 ured by the average percent absolute
 error. By this measure  Of accuracy.
 Group O has a greater error than Group
 P on samples  containing less than  20
 percent asbestos by weight. Residual
 variance  in the  transformed  data is
 measured  by the mean squared error
 about the regression line. Bythis meas-
 ure of variance. Group P was foundto be
 significantly more precise than Groups
 B and O. Further analysis of adjusted
 data indicates that  laboratories using
 point count analysis are.  better able to
 distinguish samples containing more
 than 7 percent from those with less than
 7 percent asbestos by weight than they
 are able to distinguish samples with
 more than 1  percent from those with
 less than 1 percent asbestos by weight.
  Samples from the chrysotile series
were included as within-laboratory dup-
licates. Although a more extensive effort
would be required .to adequately eval-
uate the precision of the  PLM protocol
on repeated analysis of the same sam-
ple, a gross estimate using'the present
data indicates that within-analyst vari-
ability accounts for less than 25 percent
of the total  variance.
  One of the important characteristics
of the point count procedure to  be
evaluated is the likelihood of its gener-
ati ng fa Ise positives and false negatives.

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A false positive occurs when an analyst
reports asbestos present  in a sample
that does not contain asbestos. A false
negative occurs when an analyst reports
no  asbestos present in an asbestos-
containing sample. Data  produced by
point counting included five false nega-
tives out of a total of 19 analyses of the
1.2 percent chrysotile sample. One false
negative out of 19 analyses  was reported
for  the 4.9  percent chrysotile sample.
No false negatives were reported for any
amosite  samples or for any samples
containing more than 5 percent chryso-
tile by weight. The  reporting of false
negatives is more likely due to the vari-
ability  of sample and slide preparation
steps than to the point counting proce-
dure perse.  One false positive out of 19
analyses was reported for  the series of
blank samples and was probably due to
contamination. The probability of a false
negative on the 4.9 percent chrysotile
sample was 0.05 (1/19). EPA currently
recommends the analysis of at least
three samples of a suspect material. The
rate of false negatives is such that the
analysis of three samples,  if each con-
tained  at least 5 percent  asbestos by
weight, would  result  in  three  false
negatives with a probability less than
0.03 and possibly as low as 0.001.
  The  six laboratories reporting XRD
results were gfouped into  two general
categories for p urposes of data ana lysis.
These  categories, thin-layer and bulk,
were defined on the basis of the XRD
technique used for quantitative ana lysis.
Three of the laboratories performed the
requested analyses using  some varia-
tion of  the thin-layer method ofquanti-
tation included in the Tentative Method.
The remaining three laboratories used
alternative bulk or thick-layer  methods
of quantitation. It should be emphasized
that within categories none of the
methods used were strictly equivalent.
Moreover, within the thin-layer group,
no  laboratory followed the Tentative
Method protocol exactly.
  Because  of the  small  number of
participating laboratories reportingXRD
results, and the  nonequivalence of
methods employed, it is not possible to
draw any firm conclusions from the
reported results about the accuracy and
precision of the XRD method. However,
from a  general comparison of bulk vs.
thin-layer methodology, two  observa-
tions can be made.
  First, bulk methods appear to be at
least as accurate/and precise as thin-
layer methods over the range of samples
 included in this study and significantly
 more accurate for the analysis of chryso-
 tile.
   Second, there  is a suggestion that
 thin-layer  methods of analysis may be
 more reliable (i.e., more sensitive) than
 bulk methods at the 1  percent level of
 chrysotile in a simple matrix.
   Data produced by thin-layer methods
 of analysis included one false negative
 out of three analyses of the 4.9 percent
 chrysotile sample. The same laboratory
 reported chrysotile false positives for all
 amosite  samples and  for  the  blank
 sample with reported chrysotile values
 ranging from <1 to 8 percent. A second
 laboratory reported one false negative
 out of three analyses in the 19.4 percent
'chrysotile sample.
   Data produced  by bulk methods of
 analysis  included  two  false negatives
 out of three analyses of the 1.2 percent
 chrysotile sample. One of these labora-
 tories also reported a false positive
 amosite in the 4.9 percent chrysotile
 sample.


 Recommendations
  The study presented in this report is a
 preliminary evaluation designed to de-
 termine the precision and accuracy of
 the Tentative  Method  as applied to
 carefully prepared samples. It should be
 emphasized that the samples analyzed
 consisted  of only two types of asbestos
 fiberand a single matrix material. Only
 one type of asbestos was included in
 any given sample. One of  the main
 obstacles  to  reliable analysis  of bulk
 samples  is the variability of  sample
 composition. Complete characterization
 of  the method requires that  several
 issues be  addressed, as discussed be-
 low. The  highest priority;  however,
 should be assigned to investigations
that will extend the application of the
 method to a range of real-world samples
 involving different fiber types and mat-
 rices.

Polarized Light Microscopy
  Several  aspects of the PLM  method
.require further investigation.  Briefly,
future studies should be  designed to
 determine the following:

  1.  The feasibility of specifying defini-
     tive  sample  preparation proce-
     dures to be used for quantitative
     PLM analysis;
  2.  The  proportion of total variance
     attributable  to individual  proce-
      dures of the method, i.e., sample
      preparation, sub-sampling, and
      point counting;
  3.   The proportion of total variance
      contributed^ by within-laboratory
      variability;
  4,   The effect  of specific  variables
      within the point counting proce^
      dure,  including the number of
      points to be counted, magnification
      used, and the possible bias intro-
      duced by the use of a 25-point
      reticle  instead  of a cross-hair
      reticle;
  5.   The possibility of introducing  a
      staged point counting process that
      would allow.fewer counts to be
      determined  on  samples with  a
      high percentage of asbestos;
  6.   The effect of the presence of more
      than one type of asbestos in a bulk
      sample;
  7.   The feasibility of individually cali-
      brating  PLM laboratories with
      information derived in round robiri
      sample analysis programs.

  Recommendations  for specific
changes to the method include elimina-
tion of the confidence interval calcula-
tion and revision of the rule for reporting
1 percent asbestos.
  It is apparent from the results of this
study that some type of training would
be required  to  achieve comparable
application of the PLM protocol between
laboratories. While point counting is a
classical petrographic technique,  it is
notastandard procedure inthe majority
of laboratories currently analyzing bulk
samples for asbestos. Training alterna-
tives  might include regional courses
and distribution of split samples analo-
gous  to  the  NIOSH program for. the
asbestos afr sampling method.
  It should also be noted that the PLM
method presented, although an improve-
ment over subjective techniques, is still
a procedure for estimating the relative
area occupied by asbestos fiber and
matrix material.  Alternative analytical
techniques that measure weight percent
directly or that provide an empirically
more satisfying relationship to relative
weight of  asbestos fiber should be
sought and investigated.

X-Ray Powder Diffraction
  There are two major areas in the
application of XRD techniques to quanti-
tative analysis of asbestiform minerals
in bulk materials that require further
investigation: identification andcharac-

-------
terization of standard reference mate-
rials, and further  development and
evaluation of thin-layer and bulk meth-
ods of analysis.
  The most common concern of labora-
tories participating in the evaluation of
the XRD protocol was the lack of well-
characterized, readily available refer-
ence  materials. A thorough, systematic
investigation of asbestiform materials
for use as standard materials should be
undertaken. This should include identifi-
cation of major sources; determination
of availability and cost; and complete
mineralogical  characterization and  de-
termination of purity, particle size distri-
butions, and powder diffraction patterns
of materials from these sources.
  Since asbestos minerals vary in com-
position depending  on the source and
exhibit different behaviors in grinding,
peak positions and/or relative intensi-
ties of XRD  patterns may vary from
sample  to sample.  This variability is
particularly problematic for the amphi-
bole minerals. A quantitative study to
assess the comparability of X-ray  re-
sponse of asbestos minerals from dif-
ferent sources should be conducted. If
possible, observed differences between
different samples of the same asbestos
variety should be correlated with specific
sample  characteristics (e.g., chemical
composition and particle size).
  The need for further development and
evaluation of both thin-layer and bulk
methods of XRD analysis is underscored
by the following observations: few
laboratories .are currently set  up to
routinely perform the thin-layer analysis
as prescribed; the proposed thin-layer
method of quantitation is considerably
more  time-consuming and costly than
bulk or thick-layer  methods; and  for
samples analyzed in the methods evalu-
ation  study, the;bulk method was at
least  as  acc.urate and precise as the
thin-layer method.
  In particular, a comparison of the bulk
and thin-layer methods should be made
over a variety of asbestos types and
matrix materials, with attention given to
sample preparation requirements, instru-
ment  requirements, sensitivity, preci-
sion,  accuracy, and speed and cost of
analysis.
  For both bulk and thin-layer methods,
the following areas of investigation are
proposed:


 1. Assessment of sample preparation
     requirements;
  2.  Assessment of preferred orienta-
     tion effects on quantitative.anal-
     ysis;
  3.  Assessment of the effect of the use
     of the  step-scanning  mode  of
     analysis on the limits of detection;
     and
  4.  Assessment of absorption correc-
     tion requirements and techniques.

Results and  Evaluation

Polarized Light Microscopy
  Eleven sample series were distributed
to laboratories.  Eight of the series were
targeted at specific weight percents of
asbestos fiber. Two species of asbestos
were used, chrysotile and amosite. One
matrix material, containing primarily
gypsum, was used in all prepared sam-
ples. Target weights were designed to
cover a wide range of asbestos concen-
trations approximately equally spaced
on a logarithmic scale. Blanks (Series F)
were provided as controls and for deter-
mining the method's potential for pro-
ducing false positives. The "real-world"
sample (Series J) was  included  for
comparison of between-laboratory var-
iance. Duplicates (Series K) were in-
cluded to estimate the average within-
laboratory variance. Target weights and
allowable limits for matrix and asbestos
fiber in each sample series are presented
in Table 1.
Table 1.   '  Sample Composition
  .Group means and standard deviations
are summarized in Table 2. Note that in
six of nine cases the mean (MP) of the
point count group  is closer  to the
nominal weight than the mean (MB) of
Group B. This is not a significant differ-
ence, and it appears that Groups P and B
are comparably  biased. Note  also  in
Table 2  that estimates by Group 0 are
consistently  higher .than those by
Groups  P and B.  Sign tests suffice  to
show that Group 0 is significantly more
biased than Groups  P and B.  Ninety-
percent confidence intervals were cal-
culated  for  Group P data. Using the
midpoints  of the confidence intervals,
the average percentbias was calculated
at several weight percent levels. These
are presented  in Figure 1. The percent
bias varies  with weight  percent -of
asbestos similarly for amosite and chry-
sotile samples. Point counting  has a
greater positive bias on amosite samples
than on  chrysotile samples and,  in fact,
underestimates  asbestos content  in
samples containing more than about 18
percent  chrysotile by weight.
  The standard deviation  of reported
PLM data increases as the mea n reported
area percent of asbestos increases for
all groups. Precision may be expressed
as the percent-relative standard devia-
tion or CV. CV  is related to means (MP)
for Group P in Figure 2. The CV is less
than 100 percent on samples with more
Series
C
A
E
1
H
G
D
B
F
J
Aft-
Target
Wt. %
1
; .4
16
64
2
8
16
32
0
-
Varies
Actual
Wt. %
1.2
4.9
19.4
74.5
2.5
9.8
19.4
38.8
0
50,0*
Varies
Fiber
Type
Chrysotile
Chrysotile
Chrysotile
Chrysotile
Amosite
Amosite
Amosite
Amosite
None
Chrysotile
Chrysotile
Wt. of
Asbestos (g)
0.05
0.20
0.80
3.20
0.10
0.40
0.80
1.60








.005
.01
.01
.01
.01
.01
.01
.01
None


-



Wt. of
Matrix (g)
.4.95
4.80
4.20
1.80
4.90
4.60
4.20
3.40
3.0




' 

.



 -
-

.05
.05
.05
.05
.05
.05
..05
.05
5.0


*Mean of reported areapercents, Groups P and B.
f Series K samples were provided as duplicates and included samples from series C, A,
 E, and I.
                                  4

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Table 2.    Means and Standard Deviations of Reported PLM Results, by Group (P
            B, 0)
                          (percent asbestos by area)

                                      Means
                Standard Deviations
Series  Type
                       Weight
                                MP
MB
MO
SP
SB
SO
C
A
E
1
H
G
D
B
F
J
Chrysotile
Chrysotile
Chrysotile
Chrysotile
Amosite
Amosite
Amosite
Amosite
None
Environmental
1.2
4.9
19.4
74.5
2.5
9.8
19.4
38.8
0.0
-
4.2
7.3
21.7
64.3
12.5
26.2
37.8
48.9
0.2
50.7
5.3
4.9
19.0
63.0
18.0
29.3
42.3
57.7
0.0
49.3
7.4
24.8
42.0
85.6
24.0
40.0
41.4
65.0
1.0
65.0
4.5
6.3
14.8
19.6
8.6
16.9
17.7
19.5
0.9
16.1
5.3
2.9
5.9
. 17-.3
13.9
17.3
17.5
17.4
0.0
14.7
7.3
27.5
24.6
4.7
18.3
12.7
12.4
21.5
2.2
11.2
than approximately 6 percent asbestos
by area and  less than 50 percent on
samples with more than approximately
32 percent asbestos by area. At M P= 10
percent asbestos, CV = 79 percent; at
MP = 20 percent, CVs 61 percent; atMP
= 50 percent, CV = 41 percent.
  It is of interest to evaluate the accuracy
of the PLM methods after adjusting for
the relationship between reported area
percent and th.e known weight percent
of the sample,^. This allows not only a
better understanding of what reported
PLM data mean but also indicates what
improvements might be made in data
quality by adjusting PLM area percent
estimates to  better represent weight
percent. Area percent data  were  ad-
justed for laboratory and asbestos-type
effects to yield predicted weight percent
values for each individual result.  The
most  obvious  and expected  result in
comparingthe average percent absolute
errors of treated and untreated data is
the considerable gainin accuracy (reduc-
tion of error) that results from the trans-
formation.  After  transformation,   the
average Group P inaccuracy is only one-
fifth of the original. Adjusted Group P
data are significantly more precise than
those of Groups B and 0. If laboratories
had access to information with which
they could calibrate their results (accord-
ing to the area-weight relationship for
each  laboratory and  asbestos type),
considerable  gains in  accuracy  and
precision of results could be achieved.
The gains in precision would be greater
for laboratories using the point counting
quantitation procedure than for labora-
tories using alternative procedures.
 X-Ray Powder Diffraction

   Means and standard deviations of all
 reported XRD results are shown in Table
 3. Average reported values for XRD are
 shown  for  bulk methods,  thin-layer
 methods,  and both methods together.
 Except for Series G, the  means of the
 bulk method are closer to the reference
 values than those of thethin-layer meth-
 od. Estimates of precision/given by the
 coefficient of variation, showed no sig-
 nificant difference  between  bulk and
 thin-layer methods. Considering individ-
 ual CVs, those for bulk are all less than
 or equal to those for thin-layer, except
 for Series C and B, further suggesting
 that bulk methods are at least as precise
 as  thin-layer'methods, as applied  by
 laboratories in this study.
  Comparison of the bulk and thin-layer
 methods by asbestos type i ndicates that
 for analysis  of Chrysotile,  bulk methods
 are significantly less biased than thin-
 layered  methods. No significant differ-
 ence  in slopes (bias) was  observed
 between bulk and thin-layer methods
 for amosite.
  The results do give evidence that XRD
 is capable of detecting chrysotile at the
 1 percent level in a simple matrix and
 suggest that at this level the thin-layer
 method may be more reliable. Further
 investigation is  required  to determine
 reliable detection limits over a variety of
 sample materials for both procedures.
  Bulk methods appear to be at least as
 accurate and precise as thin-layer meth-
 ods over the range of samples included
 in this  study  and  significantly  more
 accurate for the analysis  of chrysotile.
Since chrysotile is the most commonly
occurring asbestos  mineral jn bulk
insulation materials, and since most
laboratories routinely performing quan-
titative analysis of asbestos in insulation
samples use bulk methods of analysis,
use of bulk methods of XRD analysis
(ancillary  to  PLM) should  be given
further consideration.

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  100
   80
   60
   40
I
   20
   -20
  -40
amosite
chrysolite
                    <20         40           60      -..  80
                                    Asbestos we.fght percent
            100
Figure 1. Average percent bias of Group P (point count} data.

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             7.7
             7.0
             .5
        I
        1

             .7
             .6
             .5
             .4
                        chrysotlle
                        amosite
                            20
40           60
    Group P mean
80
100
         Figure 2.  Coefficient of variation of Group P (point count) data.



         Table  3.    Means and Standard Deviations of Reported XRD Results

                                      (percent asbestos)

                              Weight    Thin-Layer         Bulk          Pooled
Series
C
A
E
1
H
G
D
B
F
Type
Chrysotile
Chrysotile
Chrysotile
Chrysotile
Amosite
Amosite
Amosite
Amosite
None
%
1.2
4.9
19.4
74.5
2.5
9.8
19.4
38.8
0
M
3.0
3.3
3.7
50.0
1.5
7.0
28.0
61.0
0.2
S
2.0
3.5
3.5
7.1
0.7
5.7
12.7
11.3
0
M
1.0
4.3
18.0-
74.5
3.0
21.7
24.0
52.0
0
S
1.7
4.2
11.4
0.7
1.4
4.2
6.9
22.5
0
M
2.5
4.3
10.8
62.2
2.8
15.8
25.6
55.6
0
S
1.8
3.3
10.9
14.7
1.0
9.0
8.3
17.6
0
                                                                                                 *USGPO: 1982559-092/3407
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           E. P. Brantly, Jr., K. W. Gold. L E. Myers, and D. E. Lentzen are with the
             Research Triangle Institute. Research Triangle Park, NC 27709.
           J. J. Breen and M. E. Beard are the EPA Project Officers (see below).
           The complete report, entitled "Bulk Sample Analysis for Asbestos Content:
             Evaluation of the Tentative Method." (Order No. PB 82-196 841; Cost:
             $13.50, 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 Officers can be contacted at:
                  Environmental Monitoring Systems Laboratory
                  U.S. Environmental Protection Agency
                  Research Triangle Park, NC 27711                              ,
    United States
    Environmental Protection
    Agency
Center, for Environmental .Research
Information
Cincinnati OH 45268
Postage and
Fees Paid
Environmental
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Agency
EPA 335
    Official Business
    Penalty for Private Use $300
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