CAB100170380

Study No.  420-1171

Interim Pathology Report

Histopathology _ VC-II and T-IV groups

As detailed in the attached individual animal reports, the primary effect of the test article was limited to the lung.  All of the T-IV rats regardless of sex had a moderate to very severe chronic alveolar/interstitial consolidative lesion usually diffuse in distribution.  Elements of this lesion suggested an active process; namely the occurrence of alveolar foam cells, a protein rich alveolar transudate, and an interstitial edema with prominent interstitial macrophages.

Generally lesions present in the VC-II rats and the tissues other than the lung of the T-IV rats were typical of spontaneous and expected lesions of this species and strain at this age.  These lesions were not compound related.

Signed:  Stephen V. Becker DVM  5-11-83

TOXIGENICS

A Subsidiary of Whittaker Corporation

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CAB100170997 

PPG INDUSTRIES, INC./ONE GATEWAY CENTER/PITTSBURGH, PENNSYLVANIA 15222

October 10, 1980

Mr. L.J. Faenza

Cabot Corporation

125 High Street

Boston, MA 02110

Dear Lou:

Realizing that you are on jury duty and probably will not see this letter for some time, I will be patient for your reply.

In your letter to me of September 25 you stated your opposition to the 2mg/m³ TWA for BAA silica dust given in the second draft Silica Standard.  This was brought up during our meeting on October 7 and it was agreed that we would substitute in the third draft any value you suggested and were able to justify on the basis of feasibility.  I would recommend that the justification be as complete as possible so that those reading the standard or investigating its basis would be convinced of the practical impossibility of going lower than your recommended TWA.

I would like to add to this my plea for some documentation from Cabot regarding human safety given a history of exposure to given levels of BAA silica dust.  This need not be more than a memo report which could be filed.  Such information would serve to negate the NIOSH results and support your recommended TWA.

Let me know if you want any further discussion of this.

Best regards.

Cordially,

[signed Don]

D.D. Dunnom

Chairman

ASTM E-34 T.G.  16

DDD/jg

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 CAB100170997

CABOT CORPORATION   125 High Street, Boston, MA 02110

TEL: 617-423-6000

October 22, 1980

Mr. Donald D. Dunnom

Supervisor, Health and Safety Services

PPG Industries, INC

1 Gateway Center

Pittsburgh, PA 15222

Dear Don:

Since I am fortunate enough to have an extremely and efficient secretary, I’m getting my mail at home so that I can handle the various affairs of state while on jury duty.  So—I’m able to respond to your letter of October 10^th.

Unfortunately, Don, we don’t have much in terms of data relative to human safety which I could submit to substantiate our opinion for a higher TTLV for Cab-o-Sil.  We do have a 20 year X-ray history file which shows no pulmonary disease manifested in workers exposed to fairly high concentrations of dust over this period of time.  However, because of various legal problems, we have always hesitated to quote from this data.  The only other documentation we have is this study which Catherine Aranyl did, but these findings, as you know, are not that conclusive.  Besides, they don’t do much to prove anything on humans, per se.  I’ll have to give this more thought.

In any event, it seems to me that it ought to be fairly obvious to anyone, including NIOSH, that it is damn near impossible to maintain dust levels of our material, or any material of similar particle dimension for that matter. At 2 mg/m3 under anything but a virtually sterile atmosphere.  Anyway, I’ll get back to you on this with something.

Regards.

[signed Lou]

Louis J Faenza

LJF:sr

p.s.  Have you heard anything further from Schleyer on the proposal for the “Silica Association”?

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CAB100180069

Interoffice correspondence

cabot corporation

p.o. Box 188, Tuscola, ILlinois 61953

july 26, 1983

to:                  don rivin

from:            hector cochrane

sugject:      cab-o-sil® n70-ts fumed silica

Dear Don:

As I mentioned in my letter of July 25, in light of the new data given in Toxigenics Study 420-1171 we need to change the warning statements on our packaging and literature concerning the inhalation of  cab-o-sil® n70-ts hydrophobic fumed silica.  Drafts of the new statements are included with this letter.

I would appreciate your comments on them with any suggested changes as soon as possible.

Many thanks,

(Signed:  Hector)

HC/mc

Enclosures

CC:      RJMcCunney

            GPaci

            DRobinson

            PFTroiano

CAB100180070

cab-o-sil® n70-ts fumed silica

health safety statements

Packaging:

caution

contains treated silica

avoid breathing dust

use only with exhaust ventilation

or niosh approved respirator.

product literature:

Continued inhalation of cab-o-sil® n70-ts hydrophobic fumed silica dust may cause pulmonary inflammation.  This product should only be used with adequate exhaust ventilation or NIOSH approved respirator.

toxicoloby for health safety literature

            Histological examination of rats exposed to cab-o-sil® n70-ts hydrophobic fumed silica at 0.06 mg/l air for six hours followed by an exposure level of 0.031 mg/l air for various times up to 4 weeks was associated with a chronic-active pulmonary inflammatory process.  Twelve weeks after the four weeks of exposure, the pulmonary inflammation was more localized, however, histologic markers of chronicity were evident; namely interstitial fibrosis and interstitial collagen proliferation.  Granulomatous responses were not seen.

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CAB100180080

RETYPED FROM HANDWRITTEN NOTES

Don Rivin    12/27/82

Comments of Toxigenics  P2224

1.                    Casey’s statement that rat deaths due to mechanical effects strictly speaking should be enough.

2.                    Toxigenics P 2224—good study with reasonable dust level-re results would be meaningful but won’t really effect the result at high loading

3.                    Will talk to Billerica library & see if can get literature search for prior studies where animals died to mechanical inhalation problems.

4.                    Will write follow-up note

Highest reported carbon black inhalation studies 85mg/m3 for days → many weeks

Animals didn’t die—did suffer lung congestion & as a result suffered heart enlargement on right hand side.

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CAB100180089

Hector Cochrane (handwritten across top of page)

Heinz Dreesen c/o                                                                   Geschaftsbereich

                                                                                                Anorganische Chemieprodukte

26.11.1982

CABOT CORPORATION

Attn:    Dr. Troiano

PO Box 188

Tuscola, Illinois 61953

USA

Dear Dr Troiano,

Toxic and Health Questions related to Silica

I refer to our phone call on 24.11 and according to your request I am writing this letter to inform you that there is an increasing number of publications dealing with fibrogenic and cancerogenic effects of fumed silica.  It is a matter of interest for us to respond to these publications in a concerted action of the fumed silica suppliers.  If you would agree to take part in such an action, I would appreciate very much to name us a person who could come to Germany for a first review and contact.

Awaiting your further news with interest, I am,

Very truly yours,

DEGUS/SA   AG

Heinz Dreesen

Handwritten notes:

            I will respond affirmatively & suggest Gabe Paci—any problems?   Paul

12/14/82  Told Paul o.k.—he is getting Gregg Letterman to spell out exactly the  Cabot/Degus/sa relationships.

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CAB100180093

INTERPRETATION OF GROSS PATHOLOGY

FINDINGS-TOXIGENICS’ STUDIES

420-689            AND 420-0777

The principal finding in all exposed rats that died was a failure of the lung to collapse.  Distention of the lung in a dead animal is indicative of partial obstruction in the airways generally at the lower level of the respiratory tract.  In this instance, the experimental exposure to the test article may have greatly exceeded the ability of the rats to clear the material from the lung resulting in actual physical blockage of smaller airways by test article accumulations.  Less likely, the test article could have resulted in irritation to the lining of the respiratory tract resulting in damage to the cells and clearance mechanisms with or without subsequent exudates of serum components which combined with the test article, could have resulted in obstruction to normal air flow.

Signed: 

Harold W. Casey, D.V. M., PhD.       Date:  9/23/82

Diplomate, American College of Veterniary Pathologists

Director of Pathology

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Copies of the original of above documents may be obtained from the Breast Implant Depository in Alabama.