Document 3Q46g51Zxd2ZEQ1LwRLaRkgEa

CAMBRIDGE TO: E. S. Wood FROM: Julie C. Yang CC: R. M. Vining H. A. Brown H. C. Duecker \ 0. M. Favorito J. W. Wolter File: 71-001/-002 03643209 DATE: SUBJECT: January 6, 1977 Status on Animal Studies PLAINTIFF'S * EXHIBIT WRG-1581 The death rate of hamsters when treated with various types of chrysotile and "tremolite - talc" had been reported in a paper presented at the Talc Symposium in Washington, D.C., May 8, 1973, copy of which is attached herewith. The tremolite - talc sample referred to in the text is the Johnson-Johnson talc, composite given in Table 3. To compare his previous data (P.U6, Table 5) with the Grace test, the up-to-date progress is as follows: Sample 183 days 2U5 days Control IOO56 Libby Tremolite 5OJ6 Libby Tremolite-50$ Libby Vermiculite 0/61 0/62 1/63 (malig nant tumor) 0/61 1/62 (mesothelioma) 1/63 I'll try to reach Dr. Smith for further comments and information on parallel tests made on crocidolite (if any) or other fibers shortly after he returns from vacation. JCY:mlr attachment fi.C Juiie C. Yang WR0012823 15033594 PROCEEDINGS OF THE SYMPOSIUM ON TALC, Washington, C.C. May 8, 1973 Information Circular 3639 experimental studies on biological effects of iremolite talc on hamsters by William E. Smith, M.D.1 03643211 My name is William E. Smith. I am director of Health Research Institute at Fairleigh Dickinson University, Madison, N.J. I am a doctor of medicine. Over the past 25 years, I have studied more than 200 chemical materials for carcinogenicity in animals and have reported results of these tests in scien tific journals. In the past 8 years my associates and I exposed animals to various mineral dusts, maintained them over their natural life spans, and studied them for pathologic changes by gross and microscopic examination of their tissues and organs. The principal purpose of these latter studies has been to develop infor mation on possible fibrogenic and/or carcinogenic properties of various prepa rations of mineral dusts. The principal support for this work was provided by Research Grant EC 00226 from the Bureau of Occupational Safety and Health, U.S. Public Health Service. Thus far, we have published five papers (listed 'n the bibliography section of this paper) describing some of our findings in irnals exposed to various preparations of asbestos. Today, I would like to offer a brief summary of our experiments with asbestos and describe as yet unpublished data from studies we have made with a sample of talc containing a large amount of tremolite. From our work, we identified the Golden Syrian hamster as a species that was capable of developing pulmonary fibrosis resembling asbestosls seen in man. Those experiments were done by repeated intratracheal injections of chrysotile or amosite asbestos. The method used for those experiments, weekly intratracheal injections. Is technically tedious and time consuming. We found that we could compare the relative fibrogenicity and carcinogencity of mineral dusts more conveniently by depositing the dusts by a single injection into the pleural space of hamsters. After single intrapleural injection of preparations of the chrysotile, amosite, anthophyllite, or crocidolite types of asbestos, we found that ham sters developed extensive pleural adhesions. These adhesions were composed sainly of round cells and multinucleated giant cells in the first few months after injection. Within 5 months, these adhesions became densely fibrotic. Adhesions -inrinrud hy the chrvsotile. amosite, artCft'gWVlilUi, 01 uruuldullte types of asbestos tended to extend over large areas of the surfaces of the lungs. director, Health Research Institute, Fairleigh Dickinson University, Madison, N.J. WR0012825 3643212 44 In~contrast, ve saw very little reaction when we gave hamsters intra i pleural injections of a sample of tremolite Calc, which I shall identify by our sample number, FD-14. After intrapleural injection of this tremolite talc, the particles were gathered into small depots on the lung surface. These depots contained round cells and multinucleated giant cells, but there was i very little formation of fibrous tissue. The experiments thus show that fibrogenic activity of tremolite talc is very much less Chan the fibrogenic action of the four principal types of asbestos. Also, in hamsters that had been given intrapleural injections of the four principal types of asbestos, we found intrathoracic tumors that we designate as mesotheliomas (table 1). ZABLE 1. - Number of mesotheliomas in croups of 50 hamsters Dose, ms J 25 Vj.0 1 Chrvsotile 9 4 0 Amosite 3 0 Anthoohvllite 3 - Crocidolite 10 2 From the data in table 1, it can be seen that the yield of mesotheliomas, in groups of 50 hamsters per sample, was related to dose. In response to a large dose (25 mg) of chrysotile, nine hamsters developed mesotheliomas. In response to a smaller dose (10 mg) of chrysotile, four hamsters developed meso theliomas. In response to a still smaller dose (1 mg), there were no mesothe liomas. This experiment provides evidence to show that the carcinogenic action of chrysotile is related to dose, hence should be controllable by appropriate industrial hygiene measures to control dose. At the 10 mg dose level, amosite and anthophyllite gave about the same yield of mesotheliomas as did chrysotile, but crocidolite induced more than double the number of mesotheliomas gotten with the other types of asbestos. Also, crocidolite induced mesotheliomas in two hamsters treated with the lowest dose level (1 mg) whereas no mesotheliomas occurred in animals treated with that dose of chrysotile or amosite. Table 2 shows results of tests for carcinogencity of six preparations of chrysotile in groups of 50 hamsters each. Each of these preparations was tested at our highest dose level (25 mg per injection). The table gives data on the mean fiber length and mean fiber diameter of these samples. It can be seen that 8 to 10 mesotheliomas were induced by three of these samples: harsh chrysotile, soft chrysotile, and the same sample of soft chrysotile heattreated to achieve some of the properties of harsh chrysotile. These three samples that proved carcinogenic had mean fiber length of 5.3 to 6.9 microm eters and mean fiber diameter of 0.2 to 0.8 micrometer. These three active preparations of chrysotile were subjected to further milling to reduce the majority of particles to submicroscopic dimensions. The WR0012826 15033597 03643213 45 cable shows Chac this reduction in particle size eliminated the carcinogenic .effect of these samples. It also greatly reduced their flbrogenic action. TABLE 2. - Tests for carcinogenicity of six preparations of chrvsotile in eroups of 50 hamsters each Chrysotile preparation Soft..................... Soft (heated). Harsh................... Mean fiber leneth Mean fiber diameter OM, EM, OM, EM, micrometers micrometers micrometers micrometers 32.5 6.9 2.2 0.18 -- - - 38.9 5.3 2.9 ;2 No. of mesotheliomas 8 10 9 Soft..................... Soft (heated). - Harsh.................. - 0M Optical microscope. EM Electron microscope. .9 .4 - .03 0 -0 .07 0 Now, we have tested a sample of tremolite talc for carcinogenicity in hamsters. Electron diffraction studies of this sample showed it to contain 50 percent fibrous tremolite and 35 percent talc (table 3). A majority of the talc particles were platy, but some were rolled or fibrous. TABLE 3. - FD-14 (tremolite talc): Composition Selected area electron diffraction: Percent Fibrous tremolite............................................ 50 Antigorite........................................................... 10 Talc1....................................................................... Chlorite... ......................................................... 35 5 10f this about 75 percent is platy and 25 percent is rolled or fibrous. In this sample, the fibrous particles had an average length of 5.7 microm eters and an average diameter of 1.6 micrometers (table 4). They are there fore in a size range that might be carcinogenic in our experiments with chrysotlle. However, this sample of tremolite talc induced no mesotheliomas after intrapleural injection into hamsters. TABLE 4. - FD-14 (tremolite talc): Size measurement1 (Phase microscopy lOx ocular, lOOx objective) Length, micrometers Range Average Fibrous particles.............. 2.5-16.5 5.7 Platv oarticles.................. - - 1 Ratio fibrous to platy particles: 3 to 1. Diameter. micrometers Range Average 1- 5 1.6 1-10 2.0 WR0012827 1503359 03643214 46 Table 5 gives detailed data on these tests which were conducted at our highest dose level (25 mg). In view of the long latent period before develop ment of tumors, if we wish to compare relative carcinogenicity of different samples, validity of the comparisons depends on the number of animals surviv ing into the later periods of the tests. In table 5, the number of survivors in each group at each time period is shown as the denominator. The cumulative number of animals bearing mesotheliomas is shown as the numerator. TABLE 5. - Yields of mesotheliomas in hamsters after intrapleural injection at 25-mg dose level1 a Sample 151 340 372 450 500 550 600 650 700 days davs davs davs davs davs davs davs davs Soft chrysotile................... 0/44 0/33 1/30 1/20 4/11 4/9 7/3 8/1 Harsh chrysotile................. 1/41 4/26 4/21 7/16 7/13 7/9 8/5 9/2 o C3) Heat-treated soft chrysotile............................ 0/37 1/35 1/32 1/27 4/17 5/15 8/4 10/1 C3) Tremolite talc..................... 0/52 0/35 0/34 0/29 0/27 0/23 -QZ.20. 0/15 0/7 1 Numerator: Cumulative number of hamsters with mesotheliomas. 2Denominator: Number of hamsters surviving on stated day. 3Survivors at 650 days in chrysotile groups were killed on that day. Pleural adhesions, but no tumors, were found in them. We started with about 50 hamsters in each group. The first tumor was found at 151 days in an animal that had been treated with harsh chrysotile. Now let us look at the situation as it was 500 days after start of tests. At that time, 4 mesotheliomas had occurred in the group treated with soft chrysotile and only 11 animals survived. In the group treated with harsh chrysotile, 7 mesotheliomas had occurred and 13 hamsters were still living. In the group given heat-treated soft chrysotile, there were 4 mesothe liomas and 17 survivors. By comparison, no mesotheliomas had occurred in the group treated with tremolite talc, and there were 27 survivors. The group on tremolite talc thus had many more animals at risk in the late stages of the tests, yet no mesotheliomas developed in them. In the three groups on preparations of chrysotile, all of the animals had died or were killed to close out chose groups by 650 days. At that time, the final yield of mesotheliomas in those groups was 8, 9, and 10, respectively. By comparison, the group on tremolite talc had developed no mesotheliomas by 650 days, and there were still 15 animals living and at risk in that group at that time. WR0012828 15033599 c-643Z15 47 Eight of these survivors died of various causes between 650 and 700 days. No mesotheliomas were found in them. The remaining seven survivors on tremolite talc were killed for examina tion at 700 days. No mesotheliomas were found in them. Throughout the tests, animals treated with the preparations of chrysotile in table 5 were found to have thick fibrous pleural adhesions extending over : large areas of the lung surfaces, whereas animals treated with tremolite talc never showed more than small depots of the mineral particles with relatively little tissue reaction. In summary, our experiments show profound differences between the bio logic effects of tremolite talc, in respect to both fibrogenicity and carcino genicity, as compared with the biologic effects of the four principal types of asbestos: chrysotile, amosite, anthophylllte, and crocidollte. i WR0012829 15033600