Document 0gQbrjKvmoLk8Ly2DKEJn1pZx
,.[RS /,\l:!.IORANDUM
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Subject:
June 23 , 1977 E, Col l erd , W. Griffin
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Garden State "C:,pz-us 11iston VRpor TalJiil TRR
S&mplcs # ' s 74-77; 627-76
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In recent I:lonths , various. stfihiles by u]d)ijfil'OOX1al Institu to
for Occup~tional S;;fcty and P.cal th (NIOSH) , Hation.:1 Bu..cau of Standards (NB.5) , Occu;Jntional Safety and llealth A<l1:ti1Dst.ration (OSr.A) and Dureau of Mines he.vc e:uc:;tioned th:: technique of us:i.ng phase contrast microscopy to perform asbestos fiber dctnrr..inati.on9, In particular, talc s?.mples have caused considcri\blc controversy
because of the difficulties they present to an annlyst tn separating or definins the various types of asbestos-form fi beJ'S thnt rnay be present in many talc products ,
The Travelers Chemical and Environ7lental ubornto1-y has been aware of the controversial aspects cf the phase contrast
rr,i.c1-oscopy technique and has a.ttc:nptnd ::o make rational and accur,1tc dccisioni; in detcrmi.nr, if sar..plcs being analyzed do contain nsbcs tos fibers . i,;vl!n thoueh various precautions nre tru<r.m for the nna) yiiis of asbcsLos fibers, it has becm our concc,:rn, pm'l-1culnrly with 1,nlc , th~t the st;;,.nd.ird method of phase contrni;t microscopy 111,1)' not be adequate,
To invcstit;a tc the vnriabili ty resulting fron: the phase
contrast microscopic technique, L.he Ch,,rnical and Environment al LHboratory perfomcd a study on several Si'Jnples that. hil<I heen
previously analyzed using the standard p)1ase contrast microscopic method , All the samples in the study were bulk srunples end were
proviously reported to positively contain asbestos-form fibers . Also, nll tlle samples with the exception of one were ta) c sampl cs that had llcen submitted to determine if they were asbeotos-form talc ,
The sa':lJ)lcs ~ere analyzed by using a combination Scanning F.lectl'on l,1ic1cscop" (S"J'i!), 'l'ransrnission E1cctron l>:.icroscopc (TEM), En!!rgy Dispaisive Analysis of X-Hays ( c:DAX ) and Selectccl Area
Electron Diffraction (SAED) ,
Samples of Cyprus Industrial Viinerals Companies Jl:..iston
Vapor Talc were an3lyzed by usir.,~ these JI!Ore sensitive mr:?Lhod3 and
no nsbcstos-fcrm fibers could be found in the sa.:nlcs, All the
p nrticlcs thilt were previou::ily con9idercd fitl'!rs , when checked at
h ighe r mat;nificiation , wcrr:? reflcc~ions of talc platelets, Appr oximately fifty thousand part.icl-:?s 1-1cr!! examined frcro the:ie talc
:rnmplc:i, This indicatco there iD a 95% probability that the fiber content of these samples is less than 0.01,%.
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l examined these samples on hio different occasions,
first at a vendor laboratory where an analysis was per.forrr,ed
\tsing o SEJ/i and 'J'C::,:-F.Dt.:<-SAED syste:ns. Then, at tha invitation
of the CypI'\.ls Industrial l;j,ncr~ls Company, I went to their Los
Anselcs labo2atory and analyzed the se.ir.plcs a second time usinr,
their SE'<I ancl TEi<'.-,SJiZD systems, I would like to than.'< O, Gill
llnd C, J, Palmateer of the Cyprus Industrial Hi.neral Company
for their cooperation ln these studies,
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The Chemical and,Envi.ron.r:iental Laboratory Nas not cble to confirm its original findings of asbestos-form fi.bcr9.
We also acknowledge because of the liJ'fli tations of the r,tandarclized phase contrast rnicros<:opic technique that the original findings 'I-Jere not an accurate indication of any fibers in the product.
1The preceeding results reflect the findings of a
laboratory ot1.;1dy. Tiley ma~ not be used for or c~1e <Jonnidere.1
_to be a specific proctl1c t endorsemen t.:
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' Ronald E, l>~cCullen
Lab Administrato:r
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