historical research report - · pdf filehistorical research report research report tm/82/23...

HISTORICAL RESEARCH REPORTResearch Report TM/82/23

1982 A comparison of the effects of different counting rules and aspect ratios on the level and reproducibility of asbestos fibre counts. Part 1: Effects on level. Final report on CEC Contract ‘Counting rules for asbestos fibre measurements at work’ Howie AJ, Crawford NP

HISTORICAL RESEARCH REPORT Research Report TM/82/23

1982

Copyright © 2006 Institute of Occupational Medicine. INSTITUTE OF OCCUPATIONAL MEDICINE No part of this publication may be reproduced, stored Research Avenue North, Riccarton, Edinburgh, EH14 4AP or transmitted in any form or by any means without Tel: +44 (0)870 850 5131 Fax: +44 (0)870 850 5132 written permission from the IOM e-mail [email protected]

A comparison of the effects of different counting rules and aspect ratios on the level and reproducibility of

asbestos fibre counts. Part 1: Effects on level. Final report on CEC Contract ‘Comparison of asbestos fibre

measurements at work’

Howie AJ, Crawford NP

This document is a facsimile of an original copy of the report, which has been scanned as an image, with searchable text. Because the quality of this scanned image is determined by the clarity of the original text pages, there may be variations in the overall appearance of pages within the report. The scanning of this and the other historical reports in the Research Reports series was funded by a grant from the Wellcome Trust. The IOM’s research reports are freely available for download as PDF files from our web site: http://www.iom-world.org/research/libraryentry.php

Research Report TM/82/23 ii

Report No.: TM/82/23(EUR P.77)UDC 553.676 : 622.411.512

A COMPARISON OP THE EFFECTSOF DIFFERENT COUNTING RULESAND ASPECT RATIOS ON THELEVEL AND REPRODUCIBILITYOF ASBESTOS FIBRE COUNTS

PART I : EFFECTS ON LEVEL

by

A.J. CowieN.P. Crawford

December 1982

Report No.: TM/82/23 (EUR P77)UDC 553.676 : 622.411.512

INSTITUTE OP OCCUPATIONAL MEDICINE

A COMPARISON OP THE EFFECTS OF DIFFERENT COUNTING RULESAND ASPECT RATIOS ON THE LEVEL AND REPRODUCIBILITY OF

ASBESTOS FIBRE COUNTS


A.J. Cowie and N.P. Crawford

Final Report on CEC Research Contract : 'Counting Rules for

asbestos fibre measurements at work'

Duration of project : October — December 1981

Research Work carried out with financial aid from the

Commission of the European Communities

Institute of Occupational Medicine,Roxburgh Place,Edinburgh, EH8 9SU,Scotland.

Telephone : 031-667 5131 December 1982

iteporu no» : ii-y u^/ c.3 .cjun i~ ( f j

UDC 553.676 : 622.411.512

INSTITUTE OF OCCUPATIONAL MEDICINE





CONTENTS

Page No.

SUMMARY

1. INTRODUCTION 1

2. OUTLINE OF STUDY 1

3. WORK PROGRAMME 2'

4. RESULTS AND DISCUSSION 3

4»1 Basic Data

4»2 Effect of Aspect Ratio on the level of count

4»3 Effect of Counting Rules on level of count

4«4 Other Observations from the data

5. CONCLUSIONS 8

ACKNOWLEDGEMENTS 9

REFERENCES 9

TABLES 1-5 11

FIGURES 1-6 31

APPENDICES 1-4 Al

Report Wo.: TM/82/23 (EUR P77)


A COMPARISON OF THE EFFECTS OF DIFFERENT COUNTING RULESAND ASPECT RATIOS ON THE LEVEL AND REPRODUCIBILITY OF



A,J. Cowie and N.P. Crawford

SUMMARY

The Commission of European Communities (CEC) is currently reviewing

airborne asbestos fibre regulations and an associated reference

procedure for the membrane filter optical method of measuring fibre

number concentrations. The present study arose from a desire by

the Commission to acquire information concerning the effects of

various counting rule packages, including variants in routine use,

on the level and reproducibility of fibre counts and forms part of

a co-operative programme between the CEC and the Canadian Government.

The first stage of the investigation concerns the effects on level

of count, without taking account of interlaboratory variation, and

is reported here.

The counting rules investigated were:

(a) those developed for the United Kingdom's Central

Reference Scheme (CRS) method

(b) a modified form of the CRS rules

(c) those contained in the Asbestos International

Association's (AIA's) reference method.

These packages were each considered in combination with three different

definitions of fibre length / diameter ratio (aspect ratio) viz. >J>'.'\,

>5:1 and >10:1.

Seven European and twelve Canadian laboratories participated in the study.

Each laboratory selected samples from its own stock and evaluated them

using not only the packages described above but also employing its

routine counting protocol. In some cases, the same samples were

(ii)

evaluated by more than one laboratory, thereby providing some

information on interlaboratory variation. Six principal sample types

were incorporated in the study:f mining, milling, asbestos cement,

friction material, textile and insulation.

The effects of aspect ratio and counting rule were found to be

essentially independent of each other but both varied with sample

and sample type.

Increasing the aspect ratio from >3*1 to >5?1 reduced the level of

count on average by 12 per cent; a further increase in aspect ratio

to >10:1 produced an additional reduction of about 23 per cent in the

average counting level.

For a given aspect ratio, the level of count increased in the order

AIAQ modified-CRS (</CRS, as expected from consideration of the

counting criteria. Taking the AIA (>3:1) count as 100, the average

levels associated with the modified-CRS and CRS rules for an aspect

ratio of >3s1 were 125 and 146 respectively, and for an aspect ratio

of>5s1 were 110 and 128 respectively. Counting rules used routinely

by laboratories gave an average level of 122. The CRS (V5:1) and

modified-CRS (>3:l) rules gave counts most comparable on average to

those produced with the local rules.

These differences in level appear to be small compared with the

interlaboratory differences evident from the ;.data'/available., .ifor the

"small .jjada&xjof.' samples which were evaluated by more than one

laboratory. The significance and importance of differences in level

associated with different counting criteria can only be fully

assessed once interlaboratory differences have been quantified.

This is the aim of the next stage of the investigation and will be

reported upon separately.

Report No.: TM/82/23 (EUR P7?)






1. INTRODUCTION

The Commission of European Communities is presently considering the

question of airborne asbestos fibre standards and an associated

reference procedure for the membrane filter optical method of

measurement. This method involves manually counting fibres rendered

visible by phase contrast microscopy and was developed by the Asbestosis

Research Council (ARC, 1971). Variants of the method are currently

in use in different countries. The Commission required information

regarding the level and reproducibility of results obtained by use

of existing and proposed variants to facilitate decisions concerning

the reference method. Consequently, an investigation involving a

number of laboratories was initiated in March 1981 within the framework

of a co-operation agreement between the Commission and the Canadian

Government,

The programme was envisaged in three stages: -

Stage 1 Assessment of the relative counting levels obtained using

a variety of counting rule packages, without taking into

account the inter laboratory variability o

Stage 2 Comparison of selected counting rules with respect to the

magnitude of intra- and interlaboratory variation.

Stage 3 Action to reduce intra- and interlaboratory differences,

establishing, if necessary, a continuing quality control

programme,,

2. OUTLINE OF STUDY

This report describes the work carried out in Stage 1 of the programme.

Various counting rule packages were considered in developing a protocol

for the first stage of the study. The variations in counting criteriain routine use include differences in the basic definition of the

length, diameter and length/diameter ratio (aspect ratio) of a fibre;:,

In addition, differences arise in the counting protocols applied to

complex fibre configurations e.g. split fibres, fibres in contact with

particles and fibre bundles. Different methods of counting fibres

crossing the perimeter of the field of view to be evaluated are alsoin use.

2.

The most common definition of a fibre specifies a minimum length

of 5 /un and a maximum diameter of 3 Jim, subject to a minimum aspect

ratio of 3:1. Throughout this investigation, the length and

diameter specifications were retained but three aspect ratios, namely

>3:1, >5:1 and >10:1, were considered. This takes account of the

biological and mineralogical evidence which has emerged (WALTON, 1982)

suggesting that an aspect ratio between 5*1 and. 10:1 may be more

appropriate. The D-22 Committee of the American Society for Testing,

and Materials has included the>5:1 aspect ratio definition in the

present draft of its test method.

The counting rule variants considered for this study were:

Central Reference Scheme (CRS) rules, These form part of a reference

evaluation method developed in Britain and, as such, have been used

to compare the performance of different methods and laboratories

(CRAWFORD, To be published).

Asbestos International Association (AIA) rules. These form part of a

reference method developed by the AIA (AIA, 1979) in "an attempt by the

asbestos industry to reach international agreement". It was hoped that

publication of this method would "motivate a review of the various

national methods so that results from different countries become more

comparable".

Modified-CRS rules; These were developed during discussion in the

planning stage of the present investigation and therefore have hitherto

not been used.

The CRS and modified-CRS rules embody the principle of minimising the

number of decisions microscopists have to make; the AIA rules involve

making more decisions.

The first stage of the investigation examined these three counting

rules, each in conjunction with each of the three aspect ratios mentioned

above, and made comparisons with the local counting rules in routine use

at the laboratories concerned.

2>. WORK PROGRAMME

Seven European and twelve Canadian laboratories took part in the first

stage; these are listed in Appendix 1.

The planned work programme is detailed in Appendix 2. The three sets

of counting rules are defined in Appendix 3 and can be summarised as

follows:

CRS rules; All fibres are counted individually, whether or not

they appear to be attached to other fibres or particles.

AIA rules. Not all fibres are counted individually; some fibres

are not counted if they appear to be attached to other fibres or

particles,

Hodified-CRS rules. All visibly-free ends of fibres are counted

and the total divided by two to obtain the fibre count.

Each set of counting rules was used in conjunction with three different

aspect ratios viz. >3:1, >5:1 and >10:1. Each combination of counting

rule and aspect ratio was considered as a counting rule package, making

nine basic packages. In addition all local counting procedures used

by participating laboratories were included; these incorporate the same

aspect ratio (>3:1) but some did not limit fibre diameter.

Samples were to be selected in pairs by each laboratory covering a

range of asbestos and process types. Evaluation was to be carried

out on two separate days following the scheme detailed in Appendix 2,

In practice, however, differences occurred between laboratories both

in the type and size of graticule used and in the implementation of

the planned programme. Respective details are given in Table 1 and

Appendix 4o Throughout this report, individual laboratories have

been given alphabetic codes.

The resulting set of data was consequently complex in nature and related

to a total of 60 samples which represented seven different types of

sample. It was considered that an informal treatment involving the

summarisation and presentation of the data in tabular and graphical

form would provide an indication of the relative levels of count obtained

using the different counting rule packages. The comparative sparseness

of the data restricts the amount of additional relevant informationrecoverable through the use of more formal methods, and, since it would

be necessary to allow for the possible dependence of count variability

upon sample density and area of filter evaluated, it was decided that

the additional time and cost involved in a formal analysis of the data

could not be justified,

4. RESULTS AND DISCUSSION

4o1o Basic Data

The number of fibres counted and the corresponding number of fields

evaluated are recorded in Table 2 for the samples evaluated by each

laboratory. For almost all samples, the evaluations using the various

4.

combinations of counting rule and aspect ratio;'} criteria were repeated

on two separate days*

Table 3 contains the corresponding fibre densities (f/mm2) calculated

using the graticule field areas in Table 1. The data in Table 3 are

grouped by sample and form the basis of the comparisons described below.

4.2 Effect .-of, .-Aspect/Ratio on the Level of--.Count

In all evaluations, counts at all three aspect ratios within a given

package were obtained on the same fields of view. This was in

accordance with the planned programme (Appendix 2). The effect of

varying the aspect ratio criterion upon the level of count obtained

for the five pairs of milling samples can be seen in Figure 1. Pour

of these pairs were evaluated by more than one laboratory. The counts

obtained with aspect ratios of >5:1 and >10:1 have been expressed as

percentages of the corresponding >3:1 count.

Within a laboratory, the effect of aspect ratio does not vary greatly

from day to day, is not strongly dependent upon the counting rules

used and is generally similar for paired samples. However, the effect

of aspect ratio varies between different laboratories in their evaluation

of the same sample. Similar patterns were also found for the other

types of sample (not illustrated).

Table 4 summarises the effect of changes ttn aspect ratio both for each

sample type and overall. For each counting rule package the counts

are related to the >3:1 aspect ratio. For each sample type, the

percentages were calculated as the arithmetic means of individual

sample ratios Busing all the counts produced by the different laboratories.

The overall percentages are arithmetic means of the sample type values.

Within any particular sample type and also overall, the effect of aspect

ratio is essentially independent of counting rule package. This is

a consequence of the pattern described above for single samples. Despite

the fact that only a few samples of each type have been included in this

investigation, the effect of aspect ratio appears to vary from sample

type to sample type. For each counting rule package, an increase in

aspect ratio from >3:1 to >5:1 gives an average reduction in counting

level of some 12 per cent, with an overall reduction of around 35 per

cent being associated with an aspect ratio: ; increase to >10:1. These

values are consistent with results obtained by WINER and; COSSETTE (1979).

4.3 Effect of Counting Rules on Level of Count

The planned protocol envisaged each counting rule being applied

separately to different fieldSo In practice, some laboratories applied

all three rules to the same fields, thereby eliminating between-field

variability inherent in the planned protocol. An examination of

Table 3 indicates that, for a given ratio, the three sets of counting

rules yield fibre density estimates which are generally in the order:

AIA<CRS-MOD<CRS. This is true for either protocol and is consistent

with what is to be expected from consideration of the details of the

counting rules described in Appendix 3« Since the effect of changes

in aspect ratio are virtually independent of counting rules, it was

decided to restrict detailed comparison of the counting rules to the

conventionally used aspect ratio of >3:1 and the modified CRS rules

at >5:1.

Fibre densities obtained using the modified-GRS : method at aspect

ratios of >3:1 and >5:1 are plotted in Figure 2 and 3 respectively

against the corresponding values with AIA (A.R. >3:1) method. In

these figures, the duplicate evaluations of a sample on the two days

have not been averaged but have been plotted as separate points.

Figure 2 indicates that the modified-CRS , rules (A.R. >3:1) in almost

all cases give values higher than the AIA rules (A.R. >3:1) whereas there

is less evidence of a systematic difference between counts produced by

the modified-CRS rules (A.R. >5:1) and the AIA rules (A.R. >3:1)

(figure 3)o In the latter case, however, the variability of the

relationship is somewhat greater0

Figures 4 and 5 illustrate the relationships between counts made on

individual samples using the modified-CRS (A»R. >5:1) and the AIA

(A.R. >3:1) rules respectively and counting procedures used routinely

in the various laboratories. The AIA (A 0 R« >3:1) rules in almost all

cases give lower counts than the local rules (Figure 5) whilst counts

with the modified-CRS (A.R. >5:1) and local rules were more scattered

about the 1:1 line (Figure 4).

There is no evidence from Figures 2 - 5 of any obvious effect of fibre

density on the overall relationships between counting rule packages.

In addition, an informal examination (not detailed here) of the paired

sample data revealed no systematic difference in relationships between

packages at high and low densities.

6.

Examination of Figures 2 and 3 indicates that some of the observed

variation in the relationships appears to be associated with sample

type, e.g. the asbestos cement samples. The average level of count

from all the various counting rule/aspect ratio combinations relative

to the AIA (>3:1) count is given in Table 5 both for each sample type

and overall. The method of calculation was essentially that used to

derive the data presented in Table 4«

The following observations are made concerning the values presented

in Table 5.

1 . There appear to be differences in the relationships between counting

packages with sample type. However, the values in Table 5

derive from a small number of samples of each type. In

addition, it is not possible to separate completely the effects

in the data of laboratory and sample type since different

samples were evaluated by different laboratories,

20 For each sample type and aspect ratio, the relative levels of

count are in the order AIA modified-CRS < CRSo This reflects

the consistent pattern previously noted for the individual sample

data in Table 3.

3* For each aspect ratio the relative counts using the modified-CRS

rules generally fall mid-way between AIA and CRS counts, both

for each sample type and overall.

4. For the 3:1 aspect ratio, in current use universally, the overall

relationships given in Table 5 between the AIA, CRS and modified-

CRS rules are broadly comparable to those observed in a recent

laboratory intercomparison study primarily on asbestos cement

samples (U0 Teichert - personal communication). The values

listed in Table 5 for asbestos cement samples are numerically

higher than those observed by Teichert but the latter exercise

provided more extensive data from about 60 samples.

Local counting rules produced higher counts than the AIA rules

(A.R« 3:1) for each sample type, on average being 22 per cent

higher; the counts were lower than the CRS rules (A.R. >3:1)

by a similar amount.

7.

The modified-CRS rules (A.R. >3*1) generally yielded comparable

counts overall to those made with local rules.

Overall counts obtained using all the various packages under

consideration increase in the order:

AIA (>10:1)

AIA (>5:1) » Mbd-CRS (>10:1)

AIA (>3:1) « CRS (>10:1)

Mbd-CRS ( 5:1)

Mod-CRS (>J:1) & CRS (>5:1) ~ LocalCRS

,4*4' Other Observations from the IJata

Repeat counts were made by each counter on two separate days, this

being intended to provide some information on the comparative

repeatability of different counting rule packages. However, v the;

sparseness and complexity of the data provided measures of within-

counter variability which were insufficiently reliable to permit

firm conclusions to be drawn concerning the effects of counting rules

on repeatability.

No provision was made in the planned protocol for evaluation to be

made on the same sample by different laboratories. In practice,

however, about one-third of samples were counted by more than one

laboratory. This provides some information concerning inter-

laboratory variation. Figure 6 shows plots for mining samples of

the ratio of fibre densities obtained with the modified-CRS (A.R.>3:1)

and AIA (A.R.>3!1) rules by different laboratories. These plots

illustrate three aspects of the observed variability in the

relationship between these counting rule packages:

(a) the variability of the ratio from day to day within

a counter

(b) the range of the ratio for different samples evaluated

in the same laboratory (Figure 6a)

(c) the variation in the ratio for the same sample

evaluated in different laboratories (Figure 6b) .

In particular, it should be noted that the inter-laboratory differences

(c above) in the relationship are often large and of the same magnitude

8..

as the differences between samples observed within laboratories

(b above). These components of the observed variability are

generally larger than within-counter variation (a above) and

differences in level between methods (Table 5). The relationships-\_/between the CRS-l/DD (A.R.>J:1) and AIA (A.R.>3:1) fibre densities for

other types of sample evaluated by different laboratories show similar

features. These features also characterise the relationships between

other pairs of counting rules (at the same or at different aspect ratios),

Intra- and inter-laboratory variation over a range of samples, will be

examined in more detail in the second stage of this investigation.

;5. CONCLUSIONS

This investigation aimed to produce an indication of relative counting

levels obtained using various counting rules and aspect ratios,

without taking account of interlaboratory variation.

The effects of aspect ratio and counting rule are essentially

independent of each other, but both vary with sample and sample type.

An increase in aspect ratio from >3:1 to >5*1 reduces the level of

count on average by 12 per cent (Table 4)- A reduction in average

level of about 35 per cent is associated with an increase in aspect

ratio from>3:1 to >10:1.

For a given aspect ratio, the level of count increases in the order AIA

v<modified-CRSf<CRS. This is the order expected from consideration

of the counting criteria principles. If the AIA (>3sl) counts are

taken as 100, the average levels associated with the modified-CRS

and CRS rules for an aspect ratio of 3J1 are 125 and 146 respectively

(Table 5) and for an aspect ratio of 5*1 are 110 and 128 respectively.

Counting rules used routinely by laboratories gave an average

relative level of 122. The CRS (>5:1) and modified-CRS(>3:1) rules

therefore give counts most comparable on average to those produced

with the local rules.

These differences in level appear to be small compared with the inter-

laboratory differences evident in Figures 6a and 6b. The next stage

of the investigation will examine interlaboratory differences in

relation to the use of a few selected counting criteria and establish

whether or not better interlaboratory consistency is associated with

particular counting rules. The significance and importance of

differences in level associated with different counting criteria can

only be fully assessed once interlaboratory differences have been

quantified.

ACKNOWLEDGEMENTS

The authors are grateful to the staff of each of the laboratories for

their participation and co-operation in the investigation and to

Mr. G.W. Riley for co-ordinating the work carried out by the

Canadian laboratories.

REFERENCES

ASBESTOS INTERNATIONAL ASSOCIATION (1979) Reference method for thedetermination of airborne asbestos fibre concentrations at work-places by light microscopy (membrane filter method). London:AIA (Recommended Technical Method No. 1).

ASBESTOS RESEARCH COUNCIL (1971) The measurement of airborne asbestosdust by the membrane filter method. Rochdale (Lanes): ARC...(Technical Note 1. )

CRAWFORD NP (To be published). The United Kingdom Central ReferenceScheme for airborne asbestos fibre evaluation. Report presentedto CRS Steering Committee.

WALTON WH (1982). The nature, hazards and assessment of occupationalexposure to airborne asbestos dust: a review. Annals ofOccupational Hygiene; 25: 115-248.

WINER AA, COSSETTE M. (1979) The effect of aspect ratio on fibrecounts: a preliminary study. Annals of the New York Academyof Sciences; 330: 661-672.

11.

TABLE 1

Type and Size of Graticules used

by Participating Laboratories

LaboratoryCode

A

B

C

D

E

P

G

H

I

J

K

L

M

H

P

QR

S

T

Graticule.; . /Type

Porton

Porton

Porton

Porton

Porton

Porton

Porton

Walton-Beckett

Porton

Walton-Beckett

Porton

Porton

Walton-Beckett

(Wai ton-Beckett(BS3625

Walton-Beckett

Walton-Beckett

Walton-Beckett

(Walton-Beckett(BS3625

PattersonGlobe & Circle

Shape

Square

Square

Square

Square

Square

Square

Square

Circle

Square

Circle

Square

Square

Circle

CircleRectangle

Circle

Circle

Circle

CircleRectangle

Rectangle

Area(mm )

.003

.0025

,0025

.00308

.0025

.0041

.0025

.00785,00325

.00785

.0029

.00489

.00785

.00785

.0048

.00785

.00785

.00785

.00785

.01165

.00587

TABLE 1

TABLED. ' - * ' .

Htmber of Fibres Observed and Number of Fields Evaluated in Comparison of Counting Rules atDifferent Aspect Ratios by Various Laboratories

Lab/OQ Hi r>^ AuclttlpXO

No.

A 201-

A 101

A, 202

A 102

B:301

B 302

B 401

B 402

B 501

B 502

AIA

No. ofFields

100100 .

100100

100100

100100

100100100100100100

100100

100100

100100

No. of Fibres>3:1 >5:1

7480*

84*75*

126121

107*105

3741*92

104

4145*

23175256

1923*

66666057*8288

8473

2425

57*61*

35*39*18*14*2828*

1314*

>10:1

5252

3945*565955*4516*19384321*25*11*9*

17*18

45

CRS - Modified

No. ofFields

****

****

****

****

****

*#**

#*#*

»***

****

»***

No. of Fibres>3:1

75*80*

8575*

126121

107*105

4$92

109*

4145*

2318

5456

1925

>5:1

67*66*

6057*

8588

8473

23*26

66*

36*39*18*14*

2928*

13.16

>10:1

52*52*

3945*5659

55*.45

1720

3946

2425*129*

17*18

45*

CRS

No. ofFields

****

********

****

****

''.********

****

#***

****

No. of Fibres>3:1 >5:1 >10:1

8586

8780

127125108108

4255

1241356261

3027

6567

2435

7670

6262

8890

8575

27338083

5553

2422

35341624

57554050

5962

5748

1825

5458

34341615

2322

68

LOCAL

No. ofFields

****

#*******

-**»»#*****»** ***

**##***#

**

No. of Fibres>3:1 >5:1 >10:1

7581*

85*77*

126121

111*106

3*95

10842*45*

2318

5357*2023*

6766

6058*

8588

867424*25

63$

3739*18*14*

2928*

1314*

5352

3945*565955*45

1719394522*25*11*9*

17*18

45

** On each day only one set of fields was examined and the various counting criteria were applied in turnto each individual field.

TABLE 2-

Number of Fibres Observed and Number of Fields Evaluated in Comparison pf Counting Rules atDifferent Aspect Ratios by Various Laboratories

Lab/SampleNo.

C 211

C 212

C 1-11

C "1-12

D 221

D 222

D 121.=#

D 122

E 221

E 122

AIA

No. ofFields

100100

100100

100

100100

100100

100100

100100

100100400400

100100

No. of Fibres>3:1 >5s1 >10:1

444372*

_ 49*1711

20*294025*

145*172*

50*59

6987*

108123*111120*

•

11*1722*17••;g

4

6*7

37*18

122154*40*50

54*7495

104*92

102*

2*7

116

4*114476i

21*37

1312*1016

6454

42473

CRS - Modified

No. ofFields

*»**

****#***

** :**

#***

***#

***»

***#

*»**

****

No. of Fibres>3:1 !

5248*86*68

43*19*

3539*5943

261*277

77*79

111*116*

113125

113122*

>5:1 :

15*21

32*32

265*

15*145236*

233256

5862

8143*

100106

95104*

>10:1

2*10

15*20t

181

610

6*6*

3169*2016

1620*6855*

42*74

CRS

No. ofFields

****

**** • •********

********

»«**

**

*•»#*

****

No. of Fibres^3:1 >5:1 >10:1

6657

114896125*

4448

6349

286305

9595

133129129141122139

1928

5248

377

2218

5641

268281

686998

100

114120

103119

413

2531

251

1113

99

2988

2318

2121

8260

4586

LOCAL

No. ofFields

*#****#*

•* •

****

*#** •***#******

. **

«#»»**•***

No. of Fibres^3:1 >5:1 ^10:1

45*468f iyf58*

1.911

24*334327

152183*6567*

94*113*128

117*124

11*172618

10*4

8*7

39*18*

122*158*

50^56

S96

103*

94*102*

2*7

127

*"51

3•4*

6*6*

21*40

1715

IS645442*73

** On each day only one set of field was examined and the various counting criteria were appliedin turn to each indivudual field.

TABLE :2

Ntmber of Fibres Observed and Number of Fields Evaluated in Comparison of Counting Rules atDifferent Aspect Ratios by Various Laboratories

Lab/SampleNo.

E 121

E 222

F 222

F 221

G-131

5^32

H'111

H 301

H 41 1

H 211

AIA

No. ofFields

200200

100100

too100

197200

100100

100100

100100

100100

100100

106100

No. of Fibres>3«1 >5«1 10:1

105103*

115121*

355*304*

107*119

79*49i80*84*

4541

115129

3136

123128}

a103*109

304*276

94*101*

35*173436

31151273036

119*123*

3849*

7272*

244*224

Bt72

710

13U*90*93*2935

107*81

CRS - Modified

No. ofFields

***»

*»**

***»**

**

*»**

****

100100

100100

100100

100100

No. of Fibres>3:1 ;

107*107

125130

371*332*

113

102*969683

5158*

128*128*

5237*

166*133*

>5:1

7985

113*117*323*3041011.08*

42*3439314450

124123*5136*

156*

>10:1

•g81*79

266*25672-

-78*

76*

9*7

1830*

103*91*

4933

14699

CRS

No. ofFields

*»**

** ,***#«#»**»

****#**»

100100

100100

100100

100100

No. of Fibres>3:1 ?5:1 >10:1

111117

139146

441399138*156

93*91*98*87

4950

1451572850

149172

8291

128^132"

386367

123*133

3632

41*34

4443

1421552848

141163

4158

9391

321316

87*98

798*7*

2323

115128

2843

133129

LOCAL

No. ofFields

*#

****

****

#***

****

****

No. of Fibres73:1 >5:1 ?10:1

111*113

123132

375*321

108*120

6476*

8687*

77*81*

105*110

316285*

95*101*

27*31*

3736

%

250229*

7373*

4*8

78

•p*

** On each day only one set of field was examined and the various bountlng criteria were appliedin turn to each individual field.

TABLE ? " " . . ' • -

Number of Fibres Observed and Number of Fields Evaluated in Comparison of Counting Rules atDifferent Aspect Ratios by Various Laboratories

Lab/

No.

HJ12

H.412

H 212

H 302

H.601

H 801

H 511

r 61 1

1-601

I 512

AIA

No. ofFields

100100

100100

100100

100100

100100

100100

100100

5552

100100

9196

No. of Fibres>3:1 >5*1

8367*61*48*

248*163332315*

9693*80*78

9$127*132*

9591

115113

76536048*

222145321*2909691*52}44*

44*45*

12011992*90

109*109

>10:1

52^. 27

57^44

150J93i

274^244886831617

CRS - Modified

No. ofFields

100100

100100

100100

100100

100100

100100

41-jl 10036| 100

1103110

90389

104106

****

****

****

No. of Fibres>3:1

149*74

103*82

281207

292*361

200186

9594

1064-8gJ

77

157144*115108

142*123*

>5:1 '

14065

103*82

256*191282*342

200182

6749*

10582*

149*131*112*107

137119*

>10:1

11633*9875

198*137248*300194155

1&94,64*

140119*110*106

132116*

CRS

No. ofFields

100100

100100

100100

100100

100100

100100

'100100****

****

**#*

No. of Fibres>5:1 >5:1 >10:1

13485

134107229193343448251234116124100103186166

135129

171134

12877

131105

208185332438

249233

8380

98101

178152

132128

165129

9741

12694

156136283382

241211

3732

8976

168139

130127

160126

LOCAL

No. ofFields

****

****

»***

No. of Fibres73:1 >5;1 >10:1

•

175164128129*147*139*

167150*

125*128*

142134*

..

157*141*123*127*136*131*

** On each day only one set of field was examined and the various counting criteria were appliedin turn to each_lndividual field.

TABLE 2 ' - . . - •


Lab/On vrv«*1 AsampleNo.

I 202

I 201

J 231

J 232

J ;131

J.-*I32

K 621

K 512

K 511

K'232

AIA

1No. ofFields

7987

100100

100100

6594

100100

100100

2520

6672

100100

8357


119115

53464

10198

1221414

92457l

73

1131109}

50*60

8874;

102100

66341

49*54 35

1014! 1011112| 109

102-J 991251 1211

47564

130102

45

55*123*97

>10:1

1001041

4454

2730

28

40*1310

6410

95499

894109

38474

109483

CRS - Modified

No. ofFields

*#

***##*

100100

7092

100100

100100

2729

4447

100100

6040

No. of Fibres>3:1

119118

62!60

1121061

13311421

60l841

60

60*100107

101101

561611

101100

>5:1 '

113110*

59*56*

94f

74*102100*

44*50

4338

97104

95*96*52

60*9899

>10:1

101106

52*511

294-241

4434

1218

1418

9Cl102

8591

411511

8888

CRS

No. ofFields

#*#*

****

100100

5665

100100

100100

3020

2936

100100

4336

No. of Fibres>3:1

129134

7167

10983

121129

9171

9471

101120

100104

7157

100104

123126

6863

8762

100100

6357

7248

100117

94101

6356

9698

>10:1

111120

6058

3128

3235

2621

2319

97'109

8390

5547

8985

LOCAL

No. ofFields

******

**

100100

8590

100100

100100

2624

3244

100100

3452

-No. of Fibres

>-3:1 >5:1 >10:1

128*128*

6268

8285

1401441

84l615960

10211021

1021021

484-541

100!1021

122122

5964

6763

99]101J

534

32*4440

10C&-100

9697

48524

93|98^

1081164

5258

17181

• 3240

1984

7.8*

93484

80844

35450

7585

** On each day only one set of field was examined and the various counting criteria were appliedin turn to each individual field.

TABLE 2 : .

Ntanber of Fibres Observed and Number of Fields Evaluated in Comparison of Counting Rules atDifferent Aspect Ratios by Various Laboratories

Lab/SampleNo.

K 231

K.132

K 131

R-..401

K 402

K 302

K 301

L 112

L 111

L 1.01

L 102

AIA.

iNo. ofFields

6766

100100'

100100

100100

100100

3550100100

94100

10085

6683


101101

514.41!

'4p|

174164

2922

1004101 .

7OL=L265s

12596154i

128114

95984637459f34i1741542520

96492

704

1064

84496108

1041094

>10:1

85480

314OO=-

4721

it

241980|

64456f997246648772784

CRS - Modified

No« ofFields

4946100100"-

100100

100100

100100

3135100100

V**.

#*

***#

***#

No. of Fibres>3:1

10041004

58624

101477

42354784574107100

874103

1414102

165411715141234

>5:1

9449&4444448546541433475456|9649984100

1199212641104

13141144

>10:1

8775232357533832470455479874754883-

112

77934884

944794

CRS

No. ofFields

6250

100100

100100

100100

100100

2928

10089**

**

****

***#

No. of Fibres>3:1

10310968761196764637768107100

123100

145100

191116181125

>5:1

1001035964104526161

776510197

1189912390146

161116

>10:1

9190

4936753859547262878910890

116

78103864118

i

804

LOCAL

NO a OfFields

6966

100100

100100

100100

100100

3433100100

No. of Fibres>3:1 .

1274101

5584498974454

. 4447046012111548176

>5:1

117-i

90444472

84!434169460

11310976|68g

>10:1

957722476161

394344684578889461

"t

594

** On each day only one set of field was examined and the various counting criteria were appliedin turn to each individual field.

TABLE 2


Oft iyit-«1 Aoampj.9No.

L 132

E 1.31

L 1,21

L 212

L 211

L 201

L 202

L 232

L 231

L 221

AIA

No. ofFields

100100

100100

100100

66

50100100

81100

52696666

4450

No. of Fibres>3:1 >5x1

59458498|

14278

1034-

13641316341351144

122122

11141154

113131

424517464

10571

934

126

107504105914

1034105

1054103410713T;

>10:1

18433451436863

764

113467430g614524

76486

8280

9441234

CRS - Modified

No. ofFields

****

**

****

**

**

*#**

********

****

•**•.•**

No. of Fibres>3;1

73461

10578

157794

113

141134463

14241174

128123

11641164

1174132

>5:1

5353483464-2

120724

10341314111450

1124944

1094106

110410441114132

2536

564434

82634864

11974304684554

80487

87814

991244

CRS

No. ofFields

****

****

*#**

**

**

****

. ****

************

No. of Fibres>3:1 :

8462

11180

173481

1194

1481444641491214

1354123

12041171224133

>5:1

5954491664

134474

109

13841214511199&4

117106

11441051164133

>10:1

303762454

9465

92

12682304

744594

8787

9182

1041254

LOCAL

No. ofFields

•,

No. of Fibres5:1 >5:1 >10:1

t

00

** Onin

each day only one set of field wasturn to each individual field.

examined and the various counting criteria were applied

TABLE 2


Lab/SampleNo.

L 222

L 302

L 301

L 411

L 412

B.:701

H -702

Mr-31 1

M-312

M-421

H'422

AIA

No. ofFields

4350

37603826

2624

24

100100

2222

3237

100100

96100


121140

114133105108*

129*109

96

82*73*

103105102103*

35*42

10499

100 I 28100 I 39

105117

102*106*

100104*

109*104

94

79*73*

102104100100*

35*38*

10093

23*34

>10:1

80*97

83*8789101

105101

92*

7065

98100

75*71

2932

8879

1621

CRS - Modified

No, ofFields

*#

**

********

***#

**

92100

2020

3132

100100

5973

100100

No. of Fibres>3:1

124143

125134*108*109

129*110

99

too*103*

116100

104108

43

45*101*106*

55*46

>5:1 >10:1

108120

113*108

103*105

109*105

97

100*101*

116100

101*105

43

42*1004-101*

44*40

85100

92*

88*

92*101*

105102 '

95*

97*

96*116100

75*74

33*

35*91

88*34

32*

CRS

No. ofFields

****

********

****#*

7699

2020

2528

100100

5360

100100

No. of Fibres>3:1 >5:1 >10:1

131*146

133*137

113109*

130*116

103

102101

129149

105104

4441

103107

6366

115*123

122110*108105*

110*111

101

101101

129149

104102

4439

101100

5656

90*103

10191

97102

106108

99*

98: 96

1291498473

4032

8991

3942

LOCAL

No. ofFields

•

5861

100100

No. of Fibres>3:1 >5:1 >10:1

104105

6163

100100

5456

*

7885

43

+* On each day only one set of field wasin turn to each individual field.

examined and the various counting criteria were applied

TABLE 2

-

e

IVJ

Number of Fibres Observed and Kxaber of Fields Evaluated in Comparison of Counting: Rules atDifferent Aspect Ratios by Various Laboratories

Lab/SampleHo.

M423

M 424

M"*25

N. :321 ,

N 322

P 331 :

P 332

P 431

P 432

P 241

AIA

Ho. ofFields

100100

100100

100100

5056

100100

100100

100100

100100

3440

4350

Ho. of Fibres>3:1 >5:1

17*36

53*67*

a133135104*103*

9490*

265295

91109*

108'108*

103*107

153150*60*

ii100101*

97*84

92*85*

244*222

86*10$

103107*

99*105

>10:1

1019*33*4286*

64618065

73*70

209196

7$

7774*

6340*

CRS - Modified

No. ofFields

100100100100

100100

3647

100100

100100

4050

85100

3750

5667

No. of Fibres>3:1

42*4584793730*

108*128*

134*103

102*112*

106*122

1054-134*

114144*

124123*

?5:1 '

39*42*

77743025*

101*101

1148797*96*

97*113*

103124*110*142*

106*107

>10:1

26336261

2316*68*59*9268

88*83

89*104

98*1 < o.li1 1 C 2

107*134*V

91*97

CRS

No. ofFields

100100

too100

100100

4643

10086

100100

5050

100100

3125

3456


404382

105

3952

1411371521249379

128137

125122

128105

108112

373876983244

102102

1331068878

120131

122117

126103

101102

>10:1

2230

56792726

65719690

8574

113127

114115121101

9592

LOCAL

Ho. ofFields x

100100

100100

100100

8696

100100

-

Ho. of Fibres^3:1 J>5:1 >10:1

45439180

4534

202203101109

4038

83773725

23256658

3317

.'

•

TABLE 2 -;

Number of Fibres/Observed and Number of Fields Evaluated in Comparison of Counting Rules atDifferent Aspect Ratios by Various Laboratories

Lab/otuupXuNo.

P 242.

Q 341

•*,wQ 441

Q-451

, Q, 452

R 141

R 142

:R'521.

. R 522•

AIA

No. ofFields

100100

100100

5480

62100

100100

100100

100100

5252

7580

4544

No. of Fibres>3:1 >5t1

137,128*

6556

101*103

106101*

40*

2$

58*46*

110*123*

105*110*

111*101

127*121

6355

100100

10092

46*37*

26|

57*43*

102100*

100*100

100*101

710:1

77*61

3$

tt72*64

3*1

It4428

77*71*81*87*

8296*

CRS - Modified

No. ofFields

10082

100100

6872

7986

100100

100100100100

403158

59

2738

No. of Fibres>3:1

142*115

62*64

106103

104105

3$34*37*

74*47

141115

103*109*

106104

>5:1

12198*

61*64

106103

102*100

66*573235

71*43

103103100105

101102

>10:1

99*92*

46*53

9889

74*77

43*40

$5838

7277*

9697

9498*

CRS

No. ofFields

8254

93100

68"58

5477

100100

too100

100100

293r5539

2021

No. of Fibres^^f 4 */ • " 4

143106

12069

1-17111

106108

81*72

35*378860

133133i109106

112108

>5:1

134100

11864

109

103100

76*69

3133

7555

102100

101100

108102

>10:1

12497

9356

9391

7657

56*45

2126

5438

93••773

9290

10599

LOCAL

No. ofFields

100100

8276

7896

100100

too100

-'

No. of Fibres>3:1 >5:1 >10:1

78*51*

100*100

100100*

41*50

3526

*""' "*-, •

TABLE 2


Lab/SampleNo.

S 531

S 532

< S 541

S 542

T 461

T 462

AIA

No. ofFields

100100

100100

100100

100100

45•f

98

, No. of Fibres^3:1 >5:1 *>10:1

H14 r?*\\\ P4»2

3242

59}65*

168210J-

9696

8888

133* 123}138 B12t1•

37*

5957*

153184

9595

87*

1731*

49}47*

135155

76*

8281

CRS - Modified

No. ofFields

•f

+

No. of Fibres>3:1

&88}

>5»1

94}94*

87}

>10:1

it8181

CRS

No. ofFields

J

. +•f

No. of Fibres>3:1 >5:1 >10:1

9394

9395

9293

9294

1

7271

8585

LOCAL

No. ofFields

100100

100100

100100

100100

• ' * • - '

+

No. of Fibres/>3i1 >5:1 ^0:1

204241

4355

87119

270278

100100

8585

177216

3446

72108

231250

9999

8484

151187

2635

6595

210217

7777

7878

+ Only one set of fields were examined per sample; the fibres in each field were carefully measuredand drawn onto cards. These drawings were then assessed by two counters independently accordingto the various counting criteria.

23.

TABLE 3

Fibre Densities Obtained by Various Laboratories in the Evaluation of Samples by Different Counting Rule PackagesSample Type -

Sample No,

Lab . Code

101 A*

L,*

102 A*

L*

111 C*

L*

E.

112 C*

L*

ff

121 D*

B*

L*

122 »*

S*

131 o»

L*

f

K

132 G*

L*

J

K

Hi a

142 R

Observed Fibre Density (f/mm^)

AIA

>3:1 >5t1 >10:1

282 200 130252 192 152

274 196 136278 260 209

353 280 185350 243 150

397 322 223292 270 193

68 36 1844 16 4

196 173 148

57 45 1752 44 18

82 26 4116 28 18272 232 215

106 97 6786 68 34

164 131 42192 162 41

210 153 76207 163 99290 215 139160 145 129

224 177 32284 240 52444 368 170482 410 292

318 142 28198 68 8

201 151 104161 131 88118 84 1773 44 13

253 205 162140 119 72

322 136 28338 144 40

122 87 38120 104 6993 63 869 45 13

178 159 109143 129 78

75 73 5659 55 36

271 250 1 90303 246 175

CnS - Modified

>3:1 >5:1 >10:1 .

283 200 130252 192 152

338 259 191281 266 213

353 280 185. 350 243 150

469 407 293304 282 196

174 104 7278 22 4

209 188 157

65 56 2375 64 39

140 62 24158 56 40

308 259 244190 178 14894 83 43

252 188 65256 201 52

215 158 79214 170 105321 245 168163 143 130

362 263 52378 304 67452 380 170490 418 296

410 170 28384 136 26

215 171 116160 132 89

77 57 15108 64 23

350 295 197266 224 183

384 156 38332 124 28

150 108 51125 109 7476 55 1877 48 10

200 153 79216 160 79

95 91 7460 55 48

449 328 229473 423 318

CRS

>3:1 >5:1 >10:1

290 207 133267 207 167

391 299 211279 263 208

360 283 1 90360 250 160

561 499 366306 266 198

244 148 100102 28 4

204 184 160

62 56 2964 55 29

176 88 44192 72 52

315 268 252

171 163 124108 98 52

308 221 75308 224 58

222 164 «2234 182 116

355 275 192166 151 133

432 318 68419 325 68488 412 180556 476 344

374 144 28366 128 36

227 186 127164 136 93116 80 3390 73 27

410 359 259231 179 131

394 166 34348 136 30

172 121 61127 111 76120 92 2990 61 24

234 203 169262 221 124

112 96 6976 70 48

584 448 409547 411 316

LOCAL

>3:1 >5:1 >10:1

285 200 130258 195 152

372 287 185353 247 150

76 42 2044 16 4

98 34 12132 28 18

211 164 55219 182 49

223 155 77226 163 99

271 213 44307 258 54470 378 170496 410 292

256 110 18306 126 32

108 68 2478 41 11

338 295 210336 291 210

344 148 28350 144 32

75 53 976 51 11

190 153 76291 248 162

-

*Explanation of Sample No.: 1st digit indicates sample type. Paired samples havenumbers with identical 1st and 2nd digits.

•On each day only one set of fields was exaniined and the various counting criteriawere applied in turn to each individual field.

TABLE 3

Sheet 1

24-

TABLE 3 ' . . .

Fibre Densities Obtained by Various Laboratorleo in the Evaluation of Samples by Different Counting Rule PackagesSample Type - Milling

Sample No.

Lab. Code

201 A*

I*

L?

202 A*

I*

L*

211 C*

L*

H

212 C *

L*

H

221 I>»

B»

F*

L*

222 D*

B*

F*

L*

231 L*

J

K

232 L*

J

K-

241 P

242 P

~~ ~~ ~ : Observed Fibrs Density (fjmx?)

AIA

>3:1 >5:1 >10:1

247 220 173263 220 173

165 155 135197 185 166

268 219 138130 103 62

420 273 187403 293 197463 442 389407 387 370

341 265 155254 187 107

176 46 10172 68 28

558 515 464

157 152 137164 157 103

290 90 44198 68 24

321 290 237

317 283 192208 185 119

154 144 2798 69 25

108 95 64124 105 54

133 117 89145 124 90

525 497 439536 536 505

560 469 83663 594 H2460 4H 288486 436 290

867 743 596743 673 546

575 499 383573 479 397

345 327 254358 321 249

129 112 34125 94 38520 489 440528 512 418

480 407 301362 311 255239 200 55192 136 55540 513 455617 587 502

307 295 187273 268 103

175 162 99164 154 78

CHS - Modified

>3:1 ?5:1 ?10:1

252 225 175268 222 175

192 183 162185 174 158

175 228 151129 102 62

420 283 187403 293 197463 440 393417 391 375360 284 173240 193 113

208 62 10194 84 40

577 538 487212 199 186170 160 126

346 130 62272 128 82

350 321 268

358 327 253264 243 175

227 200 25165 UO 25113 100 68125 106 56

140 125 89157 132 96

546 518 460540 540 509

1006 896 1191065 985 267500 454 326520 470 316

906 789 650811 741 624

590 5U 404585 491 409

361 342 270361 324 253

143 • 120 38135 95 31

707 665 612753 738 562

503 431 317365 314 258243 186 80197 139 47580 563 506862 853 759

282 242 208235 203 184

182 154 127179 153 144

CRS

>3:1 >5:1 >10:1

283 253 190287 233 183218 209 185206 194 178296 248 168131 104 62

423 293 197417 300 207

502 479 432474 446 424

376 300 183248 201 122

264 76 16228 112 52

605 566 515190 180 169219 208 164

456 208 100356 192 124

370 338 285

292 265 ' 199246 236 173

242 215 35188 158 35

129 '114 82141 120 60

171 153 108190 162 120

569 541 483544 544 513

1100 1031 1121173 1081 338556 512 372584 528 364

1076 941 783973 895 771

625 549 430597 503 421

373 355 282363 325 254

139 111 39106 79 36

573 556 506752 710 621

533 460 342365 314 258275 227 73253 196 69802 770 7U996 939 814

405 378 356255 232 209

222 208 193250 236 229

LOCAL

73:1 >5:1 >IO:1

250 223 177272 233 183191 182 160209 197 170

420 283 187403 293 197500 475 421454 431 412

182 46 10184 68 28

342 104 48234 72 28

165 152 25104 71 25114 96 64128 104 54

134 118 90146 124 90

585 471 83706 610 154492 422 290528 440 290

916 771 610783 . 696 560

104 85 22108 80 24

637 585 475528 473 402

210 149 48205 144 57

1019 948 761680 653 564

See footnotes on Sheet 1.

TABLE 3Sheet 2

25,

TABLE } ' . < ' "

Fibre Densities Obtained by Various Laboratories in the Evaluation of Samples by Different Counting Rule PackagesSample Type - Textile Chrysotilo

Sample No.

Lab . Code

301 B*

L«

a

K.

302 B*

L*

H

K

31 1 M

312 K

321 N

322 V

331 P

332- p

341 Q

342 Q

Observed Fibre Density (f/om2)

AIA

>3:1 >5:1 >10:1

148 96 66162 100 76

565 538 479853 822 794

146 146 115164 162 119

250 243 222226 222 195

368 230 152416 246 172

630 567 462453 363 297423 410 350402 369 31 1

990 951 793697 634 507

406 398 301356 346 244

45 45 3754 49 41

339 255 163307 231 139

133 124 102132 107 83

120 118 94115 109 89

338 311 266376 283 250

83 80 6871 70 44

239 236 199164 159 122

CRS - Modified

>3:1 >5:1 >10:1

146 94 68166 104 60

584 557 498857 826 798

164 158 132164 157 117302 290 260355 345 305

368 230 156438 266 184

691 627 511458 368 302

373 360 317460 436 382

1190 1073 879985 975 862

427 417 310430 418 295

55 55 4358 54 45

384 359 225343 274 1 61

171 145 117131 111 87

131 124 113143 123 106

339 31 1 285311 289 265

80 78 5982 82 68

199 199 184182 182 157

CRS

>3:1 >5:1 >10:1

160 108 72220 132 100603 581 522861 830 802

185 181 146200 197 163

424 407 372387 384 349

496 320 216540 332 232

738 674 558467 377 310

437 423 361571 558 487

1272 1201 10341232 1195 1096

535 530 428473 464 332

56 56 5752 50 41

390 282 180406 302 210

194 169 122184 157 133

118 112 108101 99 94

326 306 288349 334 324

164 162 12788 82 71

219 208 174244 239 200

LOCAL

>3:1 >5:1 >10:1

154 98 68166 100 76

279 264 210262 236 205

380 238 156432 254 180

1227 1146 8921207 1139 935

489441

210227

10066

156168


TABLE 3

Sheet 3

26.

TABLE 3 . .

Fibre Densities Obtained by Various Laboratories in the Evaluation of Samples by Different Counting Rule PackagesSample Type - Anbestos Cement

Sample .No.

tab. Code

401 B*

K

402 B*

K

411 L*

K

412 I,

H

421 M

422 M

423. H

424 H

425 M

431 P

432 p

441 Q

451 Q

452 Q

Observed Fibre Density (f/nm )

AIA

>3:1 >5:1 »0:1

164 142 86182 158 102

60 60 5357 53 53

92 74 4668 58 38

100 86 8376 69 66

1019 861 826929 886 861

39 38 3746 46 45

818 801 788

78 76 7362 62 56

138 133 117126 118 101

36 30 2050 43 27

22 19 1346 39 25

68 64 4380 77 54

30 18 1027 18 8

116 110 77139 128 100

405 386 288346 342 237

218 205 149129 117 85

66 59 4452 48 40

26 22 1636 34 22

CHS - Modified

>3:1 >5:1 >10:1

164 146 96182 158 102

145 U3 131122 116 111

92 74 4872 58 38

271 260 243198 195 191

1019 861 826937 895 869

66 65 6248 46 42

844 827 814

132 132 125104 104 96

219 217 196186 177 154

71 57 4359 51 41

54 50 3357 54 42

107 98 79101 94 78

47 38 2939 32 21

158 154 148171 159 H3

392 380 370368 363 343

168 ' 165 120156 148 114

87 85 5573 73 51

44 41 2548 45 32

CRS

;>3:1 >5:1 >10:1

248 220 136244 212 136221 210 203217 210 186

120 96 64108 88 60

266 266 248234 224 214

1026 869 834988 946 920

36 36 3664 61 55

878 861 848

171 167 161136 134 120

248 243 214227 212 193

80 71 5084 71 54

51 47 2855 48 38

104 97 71134 125 101

50 41 3466 56 33

159 155 145155 H9 146

526 518 497535 525 515

250 243 179179 165 94

104 97 7292 88 57

45 39 2747 42 33

LOCAL

>3t1 >5:1 >10:1

170 148 90182 158 102

157 148 136153 141 119

92 74 4672 58 38

243 240 236. 207 207 197

228 220 171219 209 178

78 69 5580 71 56

57 51 2955 48 32

116 106 84102 98 74

57 47 4243 32 22

163133

5364

4533

TABLE 3


Sheet 4

27«

TABLE 3

Fibre Densities Obtained by Various Laboratories in the Evaluation of Samples by Different Counting Rule PackagesSmnnlp 1'vnp - tf.-trioua

Sample TypeSample No.+

Lab . Code

FrictionMaterials

501 B*

502 B»

5" • H .

K

512 ^

K

521 „

522 H

531 s

532 S

541 s

542 s

inavOationRemoval

601 I»

H

611 I*

621 K

Amosite701 H

702 H

Other

801 H

Observed Fibre Density (f/mm^)

AIA

>3:1 >5:1 >10:1

208 112 70224 1H 72

76 52 1694 53 20

59 57 5364 58 46

162 155 131195 191 164

389 370 352362 349 340536 517 468601 582 522

179 171 138176 159 139

316 285 232292 292 279

176 167 154190 172 140

40 32 2152 47 39

74 74 6282 72 59

210 191 169263 230 194

292 285 278280 277 274122 122 112119 117 87

713 671 618784 704 651

1400 1400 13171931 1879 1707

105 101 8994 94 83

596 591 567608 602 579

103 67 2099 57 22

CRS - Modified

>3:1 >5:1 >10:1

216 116 70224 114 72

76 52 16100 64 22

136 134 120109 105 82

195 179 H3212 209 178

482 463 446396 383 373792 748 666741 708 668

227 220 211236 227 209

500 477 444349 342 330

354 346 240332 329 326

255 255 247237 232 1 97

878 836 783855 778 707

1277 1239 11561272 1237 1213

139 139 135132 • 129 123

739 739 739637 637 637

121 85 38120 63 25

CRS

>3:1 >5:1 >10:1

260 140 92268 136 88

96 64 24140 96 32

127 125 113131 129 97

245 217 190197 193 162

578 558 541429 413 404

1189 1118 987996 967 862

252 234 213346 327 294

71 3 688 669655 619 601

—

415 406 400397 394 391320 317 307298 297 269

1041 996 940982 899 822

1161 1149 11152069 1017 1879

171 169 164130 130 124

822 822 822949 949 949

148 106 47158 102 41

LOCAL

^3:1 >5:1 >10:1

212 116 70230 114 72

80 52 1694 58 20

.

167 166 122188 181 172

499 480 462447 431 421

1099 1034 862803 760 662

175 152 130207 185 161

37 29 2247 39 30

75 62 56102 93 82

232 198 180239 215 186

394 386 380398 395 392

979 934 881970 891 837

1359 1333 12401473 1437 1207

.

See footnotes on Sheet 1,

TABLE 3Sheet 5

§t-1ts

TABLE 4

Effects of Aspect Ratio Changes on count level*

._\ -••Sample Type

Mining

Milling

Asbestos Cement

Textile Chrysotile

Friction Material

Others (insulation,

Amosite)

Number ofSamples

10

10

14

10

10

6

a*100

100

100

100

100

100

AIA

74

84

90

8987

92

CRS-Mod.

42

56

71

7172

80

100

100

100

100

100

100

74

84

9190

87

93

4460

777472

84

100100

100

100

100

100

CRS

75

86

93

9086

94

>10,1

4561767572

85

Mean 100 86 65 100 86 68 100 87 69

(V)CD

* Arithmetic means of counts made by different laboratories relative tothe >3s1 aspect ratio counts.

Cdtr1M\J\

TABLE 5

Relative Levels -of Count by Different Counting Rule Packages'*

Sample Type

Mining

Milling

Asbestos Cement

Textile Chrysotile

Friction Material

Others (insulation,

Amosite)

Mean

Number of

Samples

10

10

U

10

10

6

Aspect Ratio >*>:'

AIA

100

100

100

100

100

100

100

CRS-Mbd.

127112

146

109130

127

125

CRS

141

124

175125165

147

146

I

Local

117107156

121

112

118

122

Aspect Ratio >5*1

AIA

748490

8987

92

86

CRS-Mod.

92 '

95

13799116

118

110

CRS

106

107

163112

142

138

128

Aspect Ratio >10:1

AIA

4256

71

7172

80

65

CRS-Mod.

56

6711281

94

107

86

CRS

63

76

133

94119

125

102

rovo

* Arithmetic means of counts made by different laboratories relative tothe AIA (>3:1) counts.

H-<m

3 MH- H,

H-OP d-

0>J

w aE 93

*d CQ

<D rou o_ 201

1 2- 10CHO'H-CD O

CD P

M§ 80-

2d- S[>J CD ^ -O iiJ ••

^ (^ S 2 so-*'J HJ -< a <

>>5 >D _^

-* < £" ^S. ^ ^f\} * ~i / j"»-^ o —ro f^ t_> ^so

fp i-3^ ..-.^ ^ iT oCxo 2°-• a*

rt-P

P<D

0Ik y>

$. '

^V

^v

1

1 2 1 2 1

^ A IHO0H)H-

(D

H-40)

METHODAspect AIA CRS-MOD CRSRatio>5: 1 x

)10-'1 D

I

I

I

11

*H1i

j '

' 1Dow

i11

1

1

1

|

2 , 1

|

202

- P&

^

? t>

2 1 2

A I

ttf

° £

2

L

211 I

I

If 1iy1

ii

n 1

11

„ 1

' 1

'ifr ll<> !" uo ||f

Iai1 2 1 1 2 i 1

C L H1

+

«jii

*

a

2

C

212

fr fiJ9

3

)

1

L

^

tirJ!'in

ininin•it

v O

^_Ja

1

2

H

•AT

M

-O

I ••

1 2

D

0

o+*':'

221

w.Iffu. if II!

XH

!9

»

D^

2 1

E

'4vrcr'

^*ft

i

222

'«*<!

i

i*!~D

y

2 1 2 1 2 1

F L DI

1>f

1t&if

2 1

E

**" i M JInIII

*a

i

2

F

i i< i

iifctr

2

L

1

1

1

231 232

* il ll^ i

j* * it"*

1 1ii

i

f**x fi ::

P

/ :

i

j.

, *6 6 °

2 1 2 1 2 2 1 2 1 2

L J K L J K1

241 242

x

' '.T'iil

• :i1

1 1 |

PTP

! 'j; 6j,a

1 2 1 2

P PI

Sample No

DAY

LABORATORY

8,

32.

1200-

^E 1000

I

CO

A

r 800-

ena:o

600-UJQ

UJCCmLL

400-

200-

1 - MINING2 - MILLING3 - TEXTILE CHRYSOTILEU - ASBESTOS CEMENT5 - FRICTION MATERIALS6- INSULATION REMOVAL7- AMOSITEX- CLUSTER OF POINTS

1:1 RELATIONSHIP

200 400 600 800FIBRE DENSITY -AlA (A.R>3:1) f/mm2

Pig. 2 Comparison of fibre densities evaluated using the modifiedCRS (AR>3:1) and AIA (A.R. >3:1) rules

FIGURE 2

33.

UOOH

1200-

(N

I 1000

inAoL

QO

toccO

CozUJQ

LUCC00

800

600-

400-

200

1 - MINING

2 - MILLING3 - TEXTILE CHRYSOTILEt* - ASBESTOS CEMENT5 - FRICTION MATERIALS6 - INSULATION REMOVAL7 - AMOSITE

X - CLUSTER OF POINTS

2 3

0

1:1 RELATIONSHIP

200 400 600

FIBRE DENSITY- AIA (A.R.>3:11

800

Pig. 3 Comparison of fibre densities evaluation using the modified CRS

( A . R . > 5 : 1 ) and AIA (A.R. >3:1) rules

FIGURE 3

34.

1200-

& INDICATES AIA METHOD (A.R.>3:1) USED AS LOCAL RULES

a INDICATES CRS METHOD (A.R.>3:1)

A INDICATES OTHER METHOD USED LOCALLY

@—>

/1:1 RELATIONSHIP

200 400 600FIBRE DENSITY-LOCAL RULES (A.R>3:1) f/mm2

Pig* 4 Relationship between fibre densities obtained using the modifiedCRS (A.R. >5:1) and local (A.R. >3:1) rules

FIGURE 4

1200-

1000-

CM

.1

. - 800-riA

b 600 H.

UJQ

LLlCCmLL

400-

200-

35.

INDICATES AIA METHOD (A.R.>3:1) USED AS LOCAL RULES

INDICATES CRS METHOD (A.R>3:1)INDCATES OTHER METHOD USED LOCALLY

1:1 RELATIONSHIP

200 400 600FIBRE DENSITY-LOCAL RULES (A.R>3:1) f/mm^

Fig. 5 Relationship between fibre densities obtained using theAIA (A.R. >3:1) and local (A.R. >3:1) rules

0 — >

FIGURE 5

36.

1 INDICATES COUNTS ON DAT 1

SAMPLE NO.

LABORATORY

25-

<

20

1-8-

1-6-

H-

1-2-

1-0 •1 w

0-8-

0-6-

D.

Y

1

,

II1

1

1

1

1 :

1

1

1

1

1

1

1

1

|

1

1

1

1

1

1*12 12 iU 1* |

111

1

1

1

1

11

1— | 1 — | — r

*~ ON . ,_

1

>

>

'

fv

c

•

i

'

— r

f~r>

'

: .

~

F

- Cvi r.

D

i

ii

It

1.2

—i —V" ("CM r

E

>

MS

'

*™

r"<T~

?

1

1

<v

. c:

G

1II

1ii1Ii1IiIiI

' iii ;

iiiI

ii

i! 1

II

2 I

I

I

I

I

I

I

I

I

i " 5II

'

)

•r (>: f

H

!

j

'

f

£

2

1

- r-1 £

J

11L-

.

i1

« w

•

— ri1

frr-

•M l_

I

'

- C*

1 t

K

j

i

t>

*/\j

i

-iVc•r

ac< i

1

>

—

? c

o un LUM

1 1

1i

t

3 P y; ?

L

L

1

,

j ?

1

I

l 1

_ fS

i r-

1

2

1

2

— T — i —

5 3R

Fig. 6a Comparison of fibre densities obtained from milling-samplesby use of modified - CRS and AIA rules at aspect ratio >3:1illustrating day-to-day and between-sample variations withinlaboratori-es.

FIGURE

37.

ACC

Aof

10CEO

to

SLL

o

*

2-5 -

<

20 •

V8 -

1-6 -

1-4 -

1-2 -

1-fl1 U

0 -8 -

O cD

DRY

NO.

>

(

2

A

101

.

L-

.

A

102

I

<I

I

I

I

I

I

I

I

I

I

I

I

I

I

I

I

I

I

I

I

I

I

I

IiI

* I

1ii

1

1

1

1

1

11

1

L | C

|

1

>

; h11

i

)

i L1

i

.(

i

: F11

.

i

•'

-\ L

2

[

t

S

D E 1

121

I

I

I

I

!

II

I

I

I1

1

1 .1

1

1

1

1

1

11

11

1

1 .

> 1il

i '1ii1

1

1

11

1

l

1

-1 C

1

i

) E

122

,

C5 J

1

I

31

< I

L

-

i

i

•

\

J

<

H

132

i

(

( I F

u

>

>

1

.

• >

iR

V.2

Fig. 6b Comparison of fibre densities obtained from milling samples by useof modified - CRS and ASIA rules a aspect ratio >3:1 illustratingday-to-day and between-laboratory variations within samples.

FIGURE 6B

APPENDIX 1

List of Participating Laboratories

Europe

Asbest-Institut f-ur Arbeits4,inxL' Umweltschutz e.V., Neuss, W. Germany.

IMG-TNO, Delft, The Netherlands.

IMS, Nancy, France.

Institute of Occupational Medicine, Edinburgh, Scotland, U.K.

Institute Superiore Di Santa, Rome, Italy.

Laboratorium voor Industriele Toxicologie, Ministerie van Tewerkstellingen Arbeid, Brussels, Belgium.

TEA Industrial Products Ltd., Rochdale, Lancashire, England, U.K.

Canada

Carey Canada Inc., Quebec,

Johns - Manville Canada Ltd., Quebec.

Lac d'Amiante du Quebec Ltee, Quebec.

Les Mines d'Amiante Bell Ltee, Quebec.

Societe Asbestos Limitee, Thetford Mines, Quebec.

Institut de Recherche en Sante' et en Securite du Travail du Quebec(IRSST), Montreal.

Institut de Recherche et de Developpement sur I'Amiante (iRDA),University of Sherbrooke, Quebec.

Health and Welfare Canada, Ottawa.

Labour Canada, Ottawa.

Alberta Workers' Health, Safety and Compensation, Edmonton.

Ontario Research Foundation, Dept. of Materials Chemistry,Sheridan Park, Mississauga.

Dept. of Energy, Mines and Resources, Canada Centre for Mineral andEnergy Technology (CANMET), Elliot Lake, Ontario.

A2(1)

APPENDIX 2

Wbrkplan for determining the effects of various

counting rules on counting level

The purpose of stage 1 is to determine the relative counting levels

obtained using a variety of counting rules. Within the experimental

design, the results should give an estimation of the variance from:

- methods

- fibre density

- dust sources

- aspect ratio

- duplicate counting

A minimum number of ten laboratories should participate. However,

as many laboratories as possible, with different experience, should

be encouraged to take part.

It is expected that the samples selected by the laboratories for

counting will cover:

- mining

- milling

- asbestos cement

- brake lining

- textile

- insulation removal

Slides

A pair of slides is defined as two slides from their stock with the

following fibre densities:

20-40 fields/100 fibres

70-100 fields/100 fibres

Each participating laboratory selects pairs of slides from 1-4

different types of dust sources. The pairs of slides are required

to determine density effects. Single samples will only be included

in effect on counting level.

A2(2)

Counter

•(All count's were performed by one countei; in each laboratory.

List of Counting Rules

1. AIA

2. CRS

3. Mbdified-CRS

4. Local method, i.e. that is routinely used at the

laboratory (to be described by laboratory)

Counting Procedure

a. Each slide is counted once on two separate days.

Day 1 2 (NB Day 1 and Day 2

Slide 1 Slide 2 need not be

p.m. Slide 2 Slide 1 consecutive)

b. The slides are to be counted in succession according to

counting rules 1, 2, .. N. When counting the slides the

second time the counting rules are applied in reverse order.

Day 1 Day 2

AIA (3) LOCAL

CRS (3) MDD-CRS (3)

MDD-CRS (3) CRS (3)

LOCAL AIA (3)

AIA (3) represents application of the three different aspect

ratios using the AIA rules. Identify separately

those fibres in the same field of view with A.R. >10:1,

>5s1 and >3s1 and record the numbers of such fibices on

the proforma. Continue until 100 fibres with >5:1

aspect ratio are counted or 100 fields (minimum 20

fields).

Similarly with CRS (3) and MDD-CRS (3).

Local rules only require application of that laboratory's

normal aspect ratio (probably >3s1).

A2(3)

Record AIA (j results on first form

" CRS (5) results on second form

" MDD-CRS (3) results on third form

Local rule results on fourth form

(in >J:1 row) .

for each

slide

Microscope Calibration

In particular the test slides developed by HSE (lines) and AIA (latex

spheres) must be used by each laboratory.

Retention of Samples

The slides should be kept for possible further investigations.

A3(1)

APPENDIX 3

Description of Counting Rules

AIA

Rejection of Fields

Modified-CRS CRS

If more than one-eighth of the graticule area contains an agglomerate

of fibres and/or dust, reject the field and select another.

Always record such occurences.

Definition of Fibre

Each object with a maximum diameter less than 3 urn, maximum length

greater than 5 urn. and length:diameter ratio greater than A shall

be counted as a fibre. Three values of A were considered, viz.

3:1, 5:1 and 10:1.

c. Definition of "Within Graticule Area"

A fibre with both ends within the graticule

area shall be counted as one fibre; a

fibre with only one end within the area

shall count as a half.

d. "Split" and Grouped Fibres

Split fibres are

counted as one fibre

if they meet the

definition in b.

The diameter of a

split fibre is

measured across the

compact part of the

fibre, not across

the split part.

Grouped fibres are

counted individually

where individual

fibres can be

di stingui shed.

Where/

Ends of components

of split fibres or

groups of fibres

shall be counted

provided the

component meets the

definition in b,

and the end being

counted lies within

the graticule area,

and the end is

visibly free. Each

visibly free end

shall count as half

a fibre. If the

number/

A fibre with the

'lowest point' within

the graticule area is

counted as one fibre.

Each component~of a

split fibre or group

of fibres shall count

as one fibre provided

that the component

meets the definition

in b and its lowest

point is within the

graticule area, up to

a maximum of eight

fibres. If the

components cannot be

clearly distinguished,

that group or split

fibre shall count as

eight/

A3(2)

Modified-CRS

number of these

ends exceeds ten,

the group or split

fibre shall count

as five fibres.

AIA

Where they cannot

be distinguished as

individual fibres

they are counted as

one fibre if the

bundle as a whole

meets the definition

in b. Occasionally

groups of fibres are

seen as an indeter-

minate number of

fibre entranglements

which appear to

originate from the

same fibrous bundle.

These should not be

counted as fibres.

e. Fibres in Contact with Other Particles

Fibres appearing to

touch a particle are

counted as one fibre

if they meet the

definition in b and

the diameter of the

particle is less than

three micrometres.

Otherwise they are

not counted.

The visibly free

ends of fibres

defined in b which

appear to be

attached to non-

fibrous particles

shall be counted

whatever the size

of the particle.

Each visibly-free

and shall count as r

half a fibre.

Only ends lying

inside the

graticule area shall

be counted.

CRS

eight fibres.

(The simplest split

fibre comprises two

components, viz. a

main trunk and

branch which are

resolved by an

assessment of

continuity. Grouped

fibres are resolved

similarly, as are

fibres in contact

with particles).

A fibre as defined

in b and c which

appears to be

attached to a non-

fibrous particle

shall be counted

whatever the size

of the particle.

A3(3)

AIA Mbdif ied-CRS .. CRS

f. Number to be Counted

Enough graticule areas must be included to give a total fibre

count of 100. A minimum of 20 graticule areas must be includedf ^> even if more than 100 fibres are counted. It is not necessary

to include more than 100 graticule areas.

APPENDIX 4

Differences occurring between laboratories in

their implementation of the planned programme

Laboratories A-C, I and L applied all counting rule packages to the

same fields of view.

Laboratories D, E, P and H generally evaluated 100 fields, irrespective

of fibre density. Laboratories E and P additionally evaluated 200 or

400 fields on some low density samples.

Laboratory D evaluated two sample pairs; one pair was evaluated by

one observer using one microscope, the second pair being evaluated

by a colleague using a different microscope.

Laboratory N. The BSJ625 graticule was used for evaluations with

this laboratory's local procedures (at only >5*1 aspect ratio).

Counts with the other procedures were made using the Walton-Beckett

graticule.

Laboratory S. Samples were evaluated for the three aspect ratios

under consideration only using this laboratory1s local method and the

AIA method. The Walton-Beckett graticule was used with the AIA rules

(at all aspect ratios) and the laboratory's routine graticule with

its local rules (again at all aspect ratios).

Laboratory T. One microscopist examined each slide field by field,

measured the fibres and recorded each field on a card with the

graticule outline. Subsequently, that microscopist and a colleague

independently evaluated the count from the card.

Some laboratories applied their local rules at all three aspect

ratios. (see Table 2)

Some samples in the study were evaluated by more than one laboratory,

(see Table 3)

Some samples had fibre densities outside the specified range and in

some cases the difference in density between samples within a pair

were small.

HEAD OFFICE:

Research Avenue North,Riccarton,Edinburgh, EH14 4AP, United KingdomTelephone: +44 (0)870 850 5131Facsimile: +44 (0)870 850 5132

Email: [email protected]

Tapton Park Innovation Centre,Brimington Road, Tapton,Chesterfield, Derbyshire, S41 0TZ, United KingdomTelephone: +44 (0)1246 557866Facsimile: +44 (0)1246 551212

Research House Business Centre,Fraser Road, Perivale, Middlesex, UB6 7AQ,United KingdomTelephone: +44 (0)208 537 3491/2Facsimile: +44 (0)208 537 3493

Brookside Business Park, Cold Meece, Stone, Staffs, ST15 0RZ,United KingdomTelephone: +44 (0)1785 764810Facsimile: +44 (0)1785 764811

(A20115) IOM (R) ReportCov art 3/15/06 12:32 PM Page 2

historical research report - · pdf filehistorical research report research report tm/82/23...

Documents