Document M9zb46JzX9dN1MpwmozEK1Rk
f
DOW CHEMICAL U.S.A.
'AUG
August 29, 1973
MIDLAND. MICHIGAN 48840
ST0 5 / J 7 F0
R. B. Ammons, Coral Gables
B. 3. Hillary, Sarnia
T. ?. Ambrose, Brookside/Clev. J. D. Laman, Freeport
D. L. Bauer, Pittsburg
G. W. Mann, Zionsville
G. Bellinzona, Lepetit
P. G. Rudland, Sydney
R. D. Bradford, Hong Kong
E. S. Shannon, 628
F. M. Brower, 1710
M. H. Siemens, Oyster Creek
G. W. Daigre, Plaquemine
H. Tatum, Dowell/Houston
L. C. Friedrich, Parma Heights J. F. Willging, Rocky Flats
N. H. Ginn, Zurich
cc: H.
Bosscher, 2020
\ \
M. E. Pruitt, 202o\
R. R. Langner, 607
I. G. Snyder, 2020 \
C. E. Otis, 2020
P. A. Traylor, 57~~4
ASBESTOS IN WATER - ANALYTICAL METHODOLOGY
Asbestos suspended in water is receiving much attention as a potential carcinogen. It will be necessary for us to investigate the levels of asbestos in our water effluent in the near future. However, at the present time good analytical techniques for this analysis do not exist.
The Midland Division Analytical Laboratories (Pat Traylor, Don Beaman) have a sizable program underway for development of the necessary analytical methodology. The final version will probably involve the transmission electron microscope to determine morphology, electron diffraction to determine crystallinity, and some method for determining chemical composition, possibly the scanning electron microscope.
*
7
We may have an "established" method by about mid-October. It will probably involve use of the Midland facilities initially at a cost of about $100 per sample. More will follow after the next progress report scheduled for October 2.
0. Robert J. Moolenaar Environmental Affairs 2020 Dow Center
Phone 6-0655
dmw
AN OPERATING UNIT OP THc DOW CHEMICAL COMPANY
PLAINTIFF'S EXHIBIT DOW-969
"^OtX KiKi
402978
s ro 5 l3 7 8 l
THE DOW CHEMICAL COMPANY
MIDLAND, MICHIGAN January 3, 1972
C. E. Otis 2020 Building
cc:
H. C. Spencer, 1803 D. MacDougall, 574 J. Teal, 628 G. Cobel, 2020
ASBESTOS IN WATER
//V/? 7^
1. Standards - Through Jim Teal's efforts contacts were made with EPA and the State of Illinois, and current literature was consulted from other states with regard to standards for asbestos in water. No such standards or recommendations exist. Asbestos would only be included under regulations related to suspended particu lates in water.
2. Hazards - No information on the effects of asbestos in water on aquatic life was found. However, the enclosed article from Science describes an epidemiologic study on the high Incidence of stomach cancer in Japan. Asbestos as a contaminant in talc used to dust rice has been suggested as the carcinogen. Thus ingestion of asbestos, e.g. in drinking water, could be quite hazardous. I expect we will see considerable activity in this area in the future, both in the setting of standards and in laboratory studies. Asbestos standards in effluent water and food grade NaOH should be considered within Dow.
R Electrochem-Met 1703 Building Phone: 6-0655
Res
Enel
ih
402979
ST0513182
iract appears lo be a macromolcculc
Rrlnrvm tmd Nolo
no firm mincralogic definition of com
miih a mass of approximately 30.iT00 to 50.000 dallons: it is thermolabdc and destrosed by trypsin. It is appar ently not stable on long-term storage, even in the cold.
John C Houck, Hiltjc Iiuusouin ! Sanford Lr.ikiN 1 Research Foundation oj the Children's 1 Hospital of the District of Columbia, Washington, D.C. 20009. and ! George Washington Universttv School "
I. W nulUuv:n anJ (I. 1 aurcncr. Pmr. Rnr. .foe.
Ltm.fr.n s, r. U 151. 517
tan. Crll Ket.
JJ. 176 (lyrui: Aainrr 223. |U (I9:*A).
---------- l.,tr J. C.nteer 4. Ml UW-M.
3. J. Hunmaj anj k. kiwmcmj. Cell Tttitte
kmrt. I. 329
4. J. SimneU and D. Chopra, Nature 211, II59
< 1969).
5. M. Voatlcn. Exp. Eye Kse. 7. 326 (IV6K).
6. J. Mooriicad. E. Pari*i;ov.vTchcmnmNka.
A. rime. 5. Hayc. Nature 224. 1207 (19^9).
7. E. Zipihvan. 8. (luOson. W. Blau, Amt. Uu*
mem. JO. 91 (1769).
I. SupponrU in part by a contract from the
Medicine and Dentistry Division o( tnc O.Tice
ot Navai Rocarcn.
mercial talc, and in most areas the mineral talc forms much less than half of commercial talc. The composition of commercial talc varies with the de posit. Vermont mines produce a platv or granular type of mineral relatively free of asbestos minerals (6). New York and California talcs contain more fibrous silicates, including anthophyllitc and trcmolitc (2. 5).
Respired asbestos and talc dust cause
of Medicine, Washington, D.C. 20005
24 May 1971
similar disorders in workmen. Older
talc workers show more than four times
the expected incidence of lung and
j pleural cancer (7). Talc or talcosc
Talc-Treated Rice and Japanese Stomach Cancer
minerals, including contaminating as bestos, arc apparently the responsible
i Abstract. The Japanese prefer talc-dusted rice in their diet. The incidence of carcinogens since, where confirmatory
I stomach cancer in Japan is unusually high. Most taic has some asbestos con- evidence could be obtained, all those
I tanunants. Epidemiologic evidence is presented that the asbestos-contaminated talc workers with pleural and lung
I iale on rice in the diet is the carcinogen or cocarcinogcii responsible for the high cancer also had talc pneumoconiosis.
incidence of Japanese stomach cancer.
Autopsies on six talc workers with talc
pneumoconiosis showed the presence
The high incidence of stomach can showed 3.7 X 10r- asbestos-form fibers of the characteristic "asbestos body"
cer in Japanese men represents a chal per gram (Fig. 1).
in the lungs of every one (i-). When
lenging problem in cancer epidemiol
Talc, the mineral, is a hydrous sili talc is examined by phase contrast
ogy. Study of age-adjusted rates of mortality from stomacr. cancer in 24 countries showed that from 1962 to 1963 Japanese men n.id the highest rale
cate of magnesium. So are some forms of asbestos. The difference between these two minerals is not in their chem ical compositions, but rather in their
microscopy, from S to 30 percent of the particles are fibrous silicates. Identifiable trcmolitc. aiuhoplwJUic. and chrysotile are also seen (9). The large
for all nations: the rate. 67.96 per structure, asbestos being fibrous and tale deposits of New York and Cali
100.000 in the male population, was mineral, tale being flaky or granular. fornia regularly contain the ampiiibole
wven times that for men m the United However, commercial talc is composed asbestos minerals, trcmolitc and aniho-
Stales (/). Since talc frequently con not only of the pure mineral tale, but phyllile. These are normal ingredients
tains ashcMOs (7), and since workmen also of fibrous silicates, which are in of commercial laics from these areas.
.\posed lo asbestos show a marked part classifiable as asbestos. There is Chrysotile asbestos occurs in veins in
mcrea.se in gastrointestinal cancer, es
talcosc mineral deposits and may be
pecially stomach cancer (a), the hy pothesis that the increased rate of
then mined with the tale and create a contaminant (9).
cancer of the stomach in Japan is due
Asbestos is an established carcinogen.
to ingestion of rice contaminated with
Not only does it cause lung cancer, but
asbestos seems attractive and has been
it is associated with a suosianual in
recently suggested in a brief note (4).
crease of morbidity from stomach can
This report presents evidence for this
cer (J). Although chrysotile is the most
relationship at somewhat greater length.
important commercial fiber of asbestos,
Rice grown in California and meant
there is no reason to regard the ampni-
.'or the American consumer is milled
bolc asbestos minerals as safe. To the
mechanically. Rice is prepared differ
contrary in one study an amphibolc
ently for the Japanese consumer. It
asbestos mineral predominated in as-
a milled and treated with glucose, and
bcstos-bodics in the sputum of a group
:hcn talc is added. The talc is held to
of men exposed to asbestos and having
Jie surface of the gram and is said to
a high incidence o: mcsotheliomatn
preserve its flavor better. Japanese con-
</0). The fact that talc workers exposed
uder this rice more tasty, both here
to fibrous talc, which contains amphi
aid in Japan. Two percent of all talc
/ bolc asbestos, develop more pulmonary
produced in California from 1959 to
injury than do workers exposed only to
1963 was used as a rice additive, pri
talcs relatively free of fibrous silicates
marily for export to Japan (5). Riec containers in Los Angeles markets in tended for the Japanese customer usu ally bear the legend.- "Coated with (lucosc and talc." Optical microscopy of the ash of such store-bought rice
Fig. 1. Phoioniicroeraph of the ash of a specimen of nee intended for Japanese consumption and purchased in a Los Angeles market. Arrows indicate asbestosform fibers. The specimen contained 3.7 X 10* such fibers per gram.
or amphibolcs (//). indicates the patho genicity of amphibolc asbestos.
The Japanese preference tor talccoated rice means that rice eaters of that nation are exposed to the hazard of ingestion of amphibolc asbestos, as
402980
ry jrrrtoc
4029B1
well as ino unpredictable injcMion of chryvotilc m arcus u ncrc tele contai these carcinogenic materials.
Examination of I he known epidemio logic characteristics of stomach cancer in Japanese strongly suggests . at the causative agent is an additive :o rice. Not oniy is the incidcrxc of stomach cancer high in rice-eating Japanese, but inside Japan stomach czrtccr is most
a mmor d.etarv sluple (12.
In view
of the evuier.ee for ihc Japanese, the
presence of asbestos-contaminated talc
as an additive to some nationally popu
lar food should be suspected in these
countries. Further studies of the total
contamination of the common diet by
talc and asbestos in these nations with
high incidences of stomach cancer arc
nccucu.
6. II 'VttM ami T. |.*cnr*cr. Arc*. Environ. Jfi-oiUi iJ. *.<U U'N',7).
M. k ktn(cJ<J, J. Mcssite, O. kooymsA. if /jLi. ilnJ^ p. 66J.
4. M. KJemfeiU, C. Ciiel, J. Majcranovvkj, J Mcnmic. ihtd. 7, J01 f 29(0).
9. L. t jllcy. M. Key. L). Crnth. W. Lamhjrr, R- f-ito. Am. Ind. lift. Assoc. J. if, )5g f
20. J. Siiunphin* and P. Meyer, Ann. Otevp. Jlrt II. :J (196X1.
11. J. MesMie. C. Reddin. M. Kicinfeld. Am. \fed. Assoc. Anrh. but. Health 10. 408 (1959).
12. M. Sesi and M. kunlura. Tohunts J. Ess Med. 72, 169 0 960).
prevalent in those prefectures where rice is the main stapic: it is less so in prefectures where rtec is supplemented with cereal f/2) and where the popula tion cats heavily of the soybean prepa rations shovo and miso US). The mor bidity from stomach tumors is greater among Japanese who eat rice with every meal than it is among Japanese who eat it less often; among Japanese men who like milk and vegetables there is a lesser morbidity from stomach neo plasms (Id). Experimental consumption
R. R. Meruss SS20 Wihlure Boulevard, Beverly Hills, California 90211
Refemen aid Nora
3. T. Hirohaia And M. Kuratsumc. Mr. J. Cmerr. 13. 463 (1969).
2. L. A. Wn;ht, Tale and Soapstone (California Division of Mines Publications, Bulletin 276, San Francisco, 1937),
3. I. SeukolT. J. Churc. E. Hammond, J. Am. Med. Assoc, IIS. :: (1964).
4. R. Merits*, ibid. 216. 21-U (1971). 3. J. R. Wells, in Mineral Facu and Frohlemj
fU-S. Bureau at Mines, Washington, D.G,
1945).
13. M. Scpi. L. Fuktishim*. S. Fimtaku. )tf. kunhan, S. Soho. k. A*ano. M. Kamos. Comm 41 (Suppl.k 1063 (1957).
14. I. Himyama. n Froeerdtnet of the Inim*. iu>ma4 Conference on Courts Cancer (Mjnn. Tokyo. 1961).
13. A. Braunvcnwie and R. A. Rasmussen, Canerr Res. 1. 371 (1942).
26k R. OoJL P. Payne. J. Waterhouse. Cancer Incidence in Five Continents (Springer*Verlag. New York. 1966).
17. W. B. Quiscnherry. Acta Vnlo lot. Comm Cancrum 17. 528 0961).
If. W. MacDonald. Canadian Cancer Confer ence 6th (1966). pp. 451-459.
19. N. Dunpai and J. Sigurjoasson, Br. J. Cmeer 21. 270 (1967k
7 June 1971
B
|
, |J
of poiished rice will cause ulccropapillomata of the forestomacn of rats (/5).
I c
These observations suggest a relation Cyclic Adenosine Monophosphate in Brain Areas:
ship between rice consumption and
stomach cancer. However, the agent is Microwave Irradiation as a Means of Tissue Fixation
l. 'u i if
not the rice itself, sir.ee in other oriental countries where talc-coated rice is not popular the incidence of stomach can
Abstract. Amounts of cyclic adenosine monophosphate in discrete regions of the brain were estimated otter exposure of rats to microwave irradiation. Amounit
;( j.
r
cer is not unduly high.
were highest in the cerebellum and brainstem, intermediate in the hypothalamus
A final indication of the environ and midhrain, and lowest in the hippocampus and cortex. Decapitation increased
i mental causes of stomach cancer in the concentration of cyclic adenosine monophosphate in all brain areas, although
i
Japanese is provided by statistics con the increase m the cerebellum was three to jour times greater than that in other
i:
cerning its prevalence in Japanese im areas. Microwave irradiation may provide a means of rapidly fixing brain tissue in ! tei
migrants to western countries. The situ w/dlc permitting easy dissection of the brain. In this way artifacts produced ; ire
incidence in Japanese males in Japan by decapitation can be eliminated, raid concentrations of heat-stahlv compounds in
ou
in 1962 to 196-f was 77.9 per 3 00.000 the brain can be estimated under conditions which more closely approMinale those 1 I.;
(16). Japanese men in Hawaii had an its vivo.
incidence of oniy 45 per 100,000.
(li
Even this lowered rate was high com
Rapid fixation of cerebral tissue in can require up to 75 seconds to reach
pared to that for Chinese and Cauca situ is required to obtain valid estimates 0C (*) These freezing techniques also
ra.
sian men of Hawa.t who had incidences of many brain components. Decapita require restraint of the animal and pr>
of 9.2 and S.5, respectively. Native- tion and delayed fixation lead to signifi ducc considerable stress before it dies.
born Japanese nave a higher incidence of stomach cancer than Japanese bom in Hawaii or continental North Amer ica (17). Dieteti* studies on immi grant Japanese show that from 50 to
cant changes in brain glycogen (/) and in glucose, lactic acid (2), and other sub strates and cofactors of the EmbdenMeyerhof pathway (J). At present fix ation of the brain in situ is carried out
Dissection of the frozen brain is alatovi impossible, and therefore experiment, must be done on whole brains. These problems have prevented the measure ment of cyclic adenosine monophos
\\
lu
pin '.:s
70 percent of their diet is Japanese- by freezing whole animiis in liquid ni phate (.AM?) in discrete brain regie-..
type food (IS). Tnc longer the immi trogen or cooled isopentane. Even under Drug-induced changes in concentrations
grant has been in the West the more such conditions, deep brain structures of cyclic AMP in specific brain ate-,
western his diet becomes; this increase in western food in the diet coincides
might easily be masked by ma>dw amounts of unresponding tissue ur:i
H;
with a decrease in the incidence -of stomach cancer.
The hypothesis that the carcinogenic agent causing the high incidence of Japanese stomach cancer is asbestoscontaining talc on rice appears there fore to satisfy the characteristics of the known epidemiology of that form of cancer in Japan. However, standaruized mortality rates arc also high for Chile, Finland, and Iceland, where rice is not
1142
Table ]. Amounts of cyclic AM? in brain
areas after microwave irradiation. Values re present the mean and standard error of the mean from sis scparaic ccicrmir.aiions.
Area
Cyclic AMP (ntnoJe/if)
Cerebellum Uramsicm Hypoin.namus Muidram Hippocampus Cortex
1.K6 = 0.06 1.57 = 0.06
i .to r o.ru
1.43 = 0.11 0.S4 = 0.09 0.74 = 0.06
6BLUS0TS
nucleotidc concentrations are tncasutein the frozen whole brain. Furthermore, the concentration of cyclic AMP in :`.e whole brain increases severalfold in seconds after decapitation there' prohibiting rapid dissection .if;er ec_:' (5). Stavinoha (5) reported that amorof acetylcholine in the brains of that had been killed by being expo to microwave irradiation were sigr... cantly higher than previously reporxr
SCIENCE. VOL. i
- .11. J SE
Ontario Research Foundation
SHERIDAN PARK, ONTARIO. CANADA Deparcnent of Physics
Electron Optical Laboratory
(416) 822-4111 279-9771
Job No: 72190 ELECTRON MICROSCOPE WORK
MEASUREMENT OF ASBESTOS IN WATER SAMPLE
Submitted to Mr. C. R. Young Dow Chemical Co. of Canada Ltd Sarnia, Ontario
GO
--I o cn
CO ---J CO c*
402982
J?
Prepared & Approved by _______ Dr. Eric J. Chatfield Head
Electron Optical Laboratory Department of Physics December 6, 1972
File No: 88.3.2
T H11 (P0*t Ct.ATES out? TO lt # AM T 1C Ul A IDS 'UM( Hi. U4T[I|41, o* gt nf tUli(CT l(rtM(0 TO IN it. HOMiHMCSCMlMTlCMtS MDr TM4T Style** *>TlCt f ) WILL
c of iir ouutt. witmqut ix( miio* wRirTm co>si*r or thc ot**mo
rouxoATiow. ho uiuciTio >h wholc o*
rmr or i*r rct oa suas'Awct
thu
troi jKtu ec wior. udi th4u tn( *mc or r o **'0 r sracm rjuNOtMo* c us to
amt
in conur cio with i h '.&, orr hiho om aovlhi isihl cr **
MliCu 0* rO0wCt. ax* m 1 i N , imSMIC * ION 0 IHVI
(It T h C ixs Tmumi X 1 S , o a T f IAL S OM of MC SuUHCfV i'tro*ulD H * 'ImIAmiU MtSlAMCM rOimiiAI">iu
C CON'iui f(D <H *C C 0*0* hCl with Tm{ Ht 5 t TCChmiCal St amOakoi 0* t hi oh T a*iq "CSCaMCh rOUHUAt IOH HUT ML 11 Mf II If NON US I ycitlil C S Shall ftt Ml srONSifir r o
AMT loss 0 OtWtCi CSUl.TlxC DlftCCTLT OA IMUiafCtlT I MOM AH* OL I Avlt, (DUO* 0* OMIttlOH,
STO S li 7?5
1
1. Introduction
A water sample was examined by electron microscopical teehniques-Sor the presence of chrysotile asbeetos fibres. The number of such fibres per litre of water was determined and an estimate of their mass was made.
2. Experimental Technique
The amounts of asbestos in the water sample were expected to be very small; some method of concentration was therefore necessary. Much of the solid content of water samples is often organic, e.g., plant debris, bacteria, etc., and unfortunately this is also concentrated along with the asbestos. An ashing stage was therefore introduced into the process to destroy this organic material, which was of no interest in the analysis. Two methods of processing such specimens have already been described1'2, both of which have some undesirable features. The method selected for this sample combined the best features of the published techniques. The water sample was -thoroughly shaken to redisperse any solid material which may have settled out during storage. A 100ml sample of this
O was filtered through a 1000A pore size membrane filter. This pore
402983
ST05I3786
2
size was adequately snail, since fibres even shorter than this are unlikely to follow the tortuous path through such a membrane. It was necessary to assist this filtration by applying a vacuum to the clean side of the filtration equipment. The membrane filter was then placed in a silica crucible, covered with a silica lid and this was heated to 500C for a period of more than three hours. The filter residue after ashing was dispersed in 4ml of freshly distilled water, and agitated in an ultrasonic vibrator-for 10 minutes. The very heavy material was allowed to settle, and one ml of this suspension was added to a special centrifuge tube which contained a carbon coated electron microscope grid. The suspension was deposited uniformly on the electron microscope grid by operating the centrifuge at 8300g for a period of 30 minutes. The grid was then ready for inspection in the electron microscope.
The grid was examined at a direct screen magnification of 25000 times at an accelerating voltage of 80kv. Using a series of calibration circles scribed on the microscope fluorescent screen, asbestos fibres were placed into size categories according to their lengths. A minimum of 10 grid squares (200 mesh size) were examined, and all asbestos fibres in this area were counted. One problem in fibre counting was caused by the presence of large amounts of other | material. At a magnification of 25000 the area of sample examined
402984
ST05I3787
3
amounts to some 60 square metres, on which fibres perhaps as small as 3mm are being looked for among other material. This illustrates the main difficulty of the technique - that of manual counting of very widely spaced fibres; a method for which there -is no substitute on samples such as these. However, counting times of about 2 hours were adequate to size the 10 grid squares required. During the search a typical fibre was photographed.
Identification of chrysotile asbestos fibres gave rise to little difficulty. The fibre itself has a characteristic tubular appearance, and in most cases (depending on previous history) such fibres give an equally characteristic electron diffraction pattern. This pattern can be compared with that obtained from specimens of known chrysotile.
The fibre counts obtained on the sample were processed by a computer programme, and results in terms of fibres/litre were obtained, in addition to estimates of the mass concentrations. A blank sample of distilled water was processed, in order to demonstrate that asbestos was not being introduced as a result of the analytical procedures. It is very easy to think of possible sources, such as airborne material, or contamination from furnace insulation, etc. In this blank sample 200inl of distilled water was filtered and
402985
ST05I3788
-u-
Che sample processed in the same way as in the case of the other specimen. 'Jo fibres were detected in this sample.
In a further standardisation experiment, a known suspension of fibres in the size range of interest was added to a membrane filter prior to ashing. This sample indicated that the method was satisfactory, giving confidence in the results obtained on the actual sample.
3. Results
The results are shown in the computer printout (Figure 1). The concentration of fibres was U. 8 x 105 fibres per litre, which is of the same order as that in many beverages and natural sources of water.1 The sensitivity of the method can be judged by a mass calculation, assuming a density of 2.4g/cc for chrysotile asbestos. The observed fibres correspond to one part in 3.2 x 1012 parts of water. The length distribution of the fibres is shown in Figure 2. Figure 3 shows a typical asbestos fibre found in this specimen. Figures U and 5 show reference chrysotile asbestos fibres and the electron diffraction pattern obtained from one of these fibres.
402986
ST05I3789
5
4i. Conclusions The concentration of chrysotile asbestos in the water
sample vas 4.8 X 10s fibres/litre, corresponding to an estimated 3.1 x 10*4 ng/litre. This is of the same order as that in many beverages and natural sources of water.
402987
i gure i
ASBESTOS FIBRE COUNT ANALYSIS
SAMPLE: WATER SAMPLE, DOW CHEMICALS
SIZE PARTICLE NUMBER CUM CUM NO CATEGORY SIZE, UM COUNTED NUMBER PERCENT
1
0.040
0
0.0 0.00
2
0.057
2
1.0 2.56
3
0.080
7
5.5 14.10
4
0.113
7
12.5
32.05
5
0.160
5
18.5
47.44
6
0.226
5
23.5
60.26
7
0.320
7
29.5
75.64
8
0.453
1
33.5
85.90
9
0.640
3
35.5
91.03
10
0.905
0
37.0
94.87
11
1.280
2
38.0
97.44
12
1.810
0
39.0 100.00
CUM MASS PERCENT
0. 00 0.10 0.66 1.81 3.68 6.58 15.85 26. 14 40.39 51.93 75.97 100.00
TOTAL NUMBER OF PARTICLES COUNTED = 39
STGSJ3790
5 CONCENTRATION OF ASBESTOS IN SAMPLE = 4.83 X 10 FIBRES/LITRE
ESTIMATED MASS CONCENTRATION
-4 =3.11 X 10 MICROGRAMS/LITRE
THIS MASS CONCENTRATION CORRESPONDS TO ONE PART OF
12 ASBESTOS IN 3.22 X 10 PARTS OF WATER
402988
--" -- J --------- ~
sro 5/3 79/
------
Cvumi' n c 1v o N .im l.o r % l o s i th a n a C o tc d lo n ,;tl>
ST05I 3792
3 J
3
]
1
3
]
3
3 3
]
3
J --
3 3
J Figure 3. Typical Chrysotile Fibre in
Water Sample,
X53000
3
j 40299
L
'7
//
<ar", /
,;
V* H
ST05I 3 I9J
Figure U.
Reference Chrysotile Fibres, X53000
402991
5T05I379U
u/
Figure 5. Chrysotile Electron Diffraction Pattern
402992