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FILE NAME: Talc (TALC) DATE: 1973 Feb DOC#: TALC048 DOCUMENT DESCRIPTION: Journal Article - Talc- A Possible Occupational and Environmental Carcinogen Talc: A Possible Occupational and Environmental Carcinogen Hector P. Blejer, M.D., D.I.H. and Robert Arlon, Pharm. D. ale is mineralogically closely related to three of the five major asbestos group minerals, specifically, the serpentine Chrysotile, as wejl as the first two of the amphiboles Anthophyllite, Tremolite, Amosite and Crocidolite. In certain toxicological aspects, talc and asbestos are also closely related: They are silicates which produce fibrosis of the lung and other tissues. Talcs and the asbestos minerals cited are hydrous magnesium silicates difficult to dif ferentiate-- except w ith special techniques such as electron microscopy with selected area diffraction-- and which form in the same as well as similar geological processes. Con sequently, many talc deposits contain asbestos minerals, so that in industrial and commercial use, such talcs always contain varying amounts of asbestos fibers. Because of this asbestos con tamination of talcs, we reviewed data on: (1) The composition of talc and related asbestos minerals; (2) The toxic effects of both substances; (3) The general environmental exposures to talc; and (4) Its common uses, including those involving ingestion of talccontaining foods and drugs. Ad ditionally, (5) Mineral residues from talc-coated rice washings were analyzed for asbestos. Then we re-evaluated such data, together with new findings on the asbestos contamination of talc-coated polished white rice. As a result, we present some new conclusions about related possible health risks arising from occupational and environmental ex posures to asbestos contaminated talcs. than a mineral species: It includes all gradations, from the pure mineral to im pure massive talcose rocks, such as soapstone. In fact, some commercial talc deposits can contain a very small talc content with varying amounts of many Definitions and Composition of Talc accessory minerals, such as asbestos, quartz, and other "impurities." In the Pure talc and the three related United States, for example, the Saint asbestos group minerals are hydrous Lawrence County, New York State com magnesium silicates whose theoretical mercial talc deposits contain 30% or less chemical formulae are: of mineralogically pure talc. The remain der consists partly of: (1) Serpentine, the True Talc Mgs Sis O 20 (O H) 4 host mineral of chrysotile, antigorite and Anthophyllite Asbestos Mg7 Sis O 22 (OH) 2 Chrysotile Asbestos Mgs Sm O 10 (O H)s Tremolite Asbestos Ca2 Mgs Sis O 22 (O H ) 2 Mineralogically, there are two forms of talc: Nonasbestiform, also called platy or nonfibrous, and Fibrous, also called trem olitic. As used com m ercially, however, the term "talc" connotes cer tain desired physical properties rather lizardite; (2) Tremolite; and An thophyllite, which can convert naturally to talc. Although mineralogical "im purities," the asbestos minerals are con sidered in many cases as an integral part of such commercial talc, whereas other m ineralogical im purities, such as hematite and pyrite, are commercially unacceptable.1 An example is that talcs Dr Blejer is Medical Officer and Head, O c cupational Health, Southern California Bureau of O c cupahonal Health and Environmental Epidemiology State of California Department of Public Health lo Angeles, and Assistant Clinical Professor of Medicine School of Medicine, University of Southern Califor nia, Los Angeles Dr. Arlon i, from Kaiser Foundatior Hospitals, Los Angeles. Reprml requests to 1449 Temple SI. Suite 10f> Lry Angeles 90026 (Dr. Blejer). ' Presented in part at the 15th annual Weslern In- 1 1971 Heai,h Conference- San Francisco, Oclobei 92 i US data not available, but figure should be only slightly less than 11.1. 4 US data not available, but these are rare causes of death in the general population ol the Lung and Plcuia and Gas andPar)tolieumii1teli$dKi;ip Deaths From Proportional Mortality? . K "- gfl; .G ro u p J\ Rjotal ~ " . B Less; than 40 j j j 4 0 -,5 9 . f c b i- ,'7 9 , j . . J | j B j i i `n i; pYw - ? Malignant Causes ^ I t and Pentonaim Total Deaths ^ Liin ijfn d ! Pleura 6 1* and Peritoneum s o u . . * ! .p h i i l w T i Theoremcaj 91 s p is 2 ' '38 * .< i * 1 4 ... 1 nr-'-; 1 l f p K m * 7 7i h 5 34 ( fig i i g j j i ss: ' 5 3 * 55S 39 .. Mi , , * After Klemfeid et a l.3 t Number of deaths in a group divided by total deaths in same group x 100. * Gastrointestinal tract. $ Difference not sta tistically significant, ii Difference sta tistica lly significant (p = < 0 .0 1 ). Statistical ana lysis not done due to sm all number in group. for milling are often chosen preferen tially on the basis of how much "Im purity" Is present, apparently because talc with larger, purer grains Is more dif ficult to mill. Also of note is that the most recent revision of the US Phar macopeia2 does not specifically exclude asbestos as an Impurity In its definition of pharmaceutical grade talc. The World Health Organization3 In its 1971 reevaluatlon of food additives noted that asbestos is a contaminant in some talcs. All of these are factors which make it im perative to ascertain the mineraloglcal type and purity of talcs in assessing their potential health effects. Toxic Effects Asbestos. -- Different forms of asbestos appear to have different biological effects. These differences are still too incompletely understood and complex to be discussed here, except as mentioned briefly below. Nevertheless, It can be stated that carcinogenicity is the most serious toxic effect of the various asbestos group minerals. In the last few decades In particular, these substances, especially some types of crocidollte, have been occupationally associated with greatly excessive incidence of pleural and peritoneal mesotheliomas, previously extremely Infrequent cancers in humans.4 Moreover, a number of researchers have experimentally Induced pleural mesotheliomas after Intrapleural Injection of various forms of asbestos and demonstrated the neoplastic nature of those tumors.5 As shown In Table 1, Selikoff et al6 recently reported that among a cohort of 632 asbestos in sulation workers, of the 418 deaths ob served from January 1, 1943, to June 30, . 1971, 20% were due to bronchogenic carcinoma, 10% to cancer of the stomach, colon, and rectum, and 6% to pleural and peritoneal mesothelioma. The asbestos forms used In the past by these workers were mostly chrysotile and amosite, with possibly small amounts of croddolite. As a group, the same asbestos In sulation workers show about eight times an excess mortality from bronchogenic carcinoma. Moreover, asbestos in sulation workers who smoke have a 92 fold risk of dying from bronchogenic car cinoma, as compared with men who neither smoke nor work with asbestos.7 Thus, this type of occupational asbestos inhalation exposure points to another ef fect of asbestos, that of a cocarcinogen. The asbestos group minerals have the added toxic effect of fibrogenicity which results in: Asbestosis, the well-known occupational lung fibrosis due to chronic inhalation overexposure; Pleural plaques and calcifications; as well as the less well-known asbestos corns or "warts" of the skin among workers handling such materials. As mentioned, toxicological effects of different forms of asbestos appear to be different. For example, as compared with chrysotile, exposure to the amphiboles Is generally more likely to produce asbestosis and bronchogenic carcinoma. Also, Inhalation of crocidolite--es pecially of some types with shorter, finer fibers as measured by electron microscopy--appears to produce more mesotheliomas than other amphiboles and chrysotile. This subject was reviewed recently and succinctly by Wagner.8 In addition, inhaled asbestos particles retained in lung tissues can be covered with a proteinaceous-iron coating which produces a type of ferruginous body commonly termed "asbestos body." Talc. -- As shown in Table 2, Klein feld et al9 demonstrated that talc miners and millers in Northern New York State have 3.4 times an excess mortality from lung and pleural carcinomas. Such ex cess was shown to be statistically significant and appeared 20 years later than among asbestos insulation workers. The New York investigators ascribed this difference, in part, to talc being less car cinogenic than asbestos, without con sidering the fact that talc deposits in the northern part of that state contain much asbestos, as we noted above. No significant difference was found be tween the observed and expected mor tality from carcinoma of the gastroin testinal tract and peritoneum among these talc workers.9 A w ell-know n effect of talcs, especially the fibrous variety, is talcosis, another of the many-occupational lung fibroses. Other toxic effects are the production of granulomas In wounds and scars, and intense mesothelial Irritation, with fibrosis and adhesion In the pleural and peritoneal cavities. These occurred often in the past, due to the operated tissues being contaminated with the talc used as dusting powder for and shed from surgical gloves-- a use no longer recommended.10 Likely for similar reasons, the Kaiser Foundation Hospital In Los Angeles discontinued the use of "talcum" powders for any Inpatient use. A bizarre, new and serious talc effect is that of pulm onary intravascular granulomas with vascular thrombosis and sclerosis leading to pulmonary hypertension, due to intravenous In jection of talc-containing oral tablets and talc-adulterated substances in drug misuse.11 Inhaled fibrous talc particles can also be changed by cells in the lung into another type of ferruginous body which some call "talc bodies." Hygienic Work Standards Asbestos. -- For 1972, the Comm ittee on Threshold Lim it Values for Airborne Contaminants of the Am erican Con ference of G overnm ental Industrial Journal of Occupational Medicine/Vol. 15, No. 2/February 1973 93 Hygienists (ACCIH) has proposed a earlier in the year by the National In and illustrated in the Figure. the time-weighted, average limit value (for stitute for Occupational Safety and Talc. -- For 1972, the ACGIH has a wk an 8-hour workday, 40-hour workweek) Health, Public Health Service, US De TLV for each form of talc:12 anc for all forms of asbestos of 5 fibers per partment of Health, Education, and (a) Nonasbestiform Talc 20 million par rep milliliter longer than 5 fj. in length, as Welfare--was adopted for all forms of ticles per cubic foot of air (mppcf), thr< determined by the membrane filter asbestos, effective July 1, 1976, by the based on the Light-field dust count. asb method at 430-times magnification Occupational Safety and Health Ad (b) Fibrous Talc: The same TLV of 5 cor phase-contrast illu m in atio n .12 This ministration (OSHA), US Department of fibers discussed above. Cit' Threshold Limit Value (TLV) has been Labor. Until that effective date, the 5- The Documentation for these TLV's takes fou developed as the air concentration of fiber TWA discussed above applies as into account the different biological ef chr asbestos fibers which (1) should afford the US standard for all forms of fects of the two forms of talc and of the Mo protection against asbestosis, and (2) asbestos.14 need to determine their type and in . reduce to an acceptably low risk the It should be noted that all these stand purity.13 talc development of neoplasms. This TLV ards are based on the identification and The revised Table G-3-- Mineral Dusts of " does not assure complete elimination of quantification of all forms and types of in the same OSHA standards cited15 lists hac the carcinogenic risk because of in asbestos fiber by phase-contrast (op only one hygienic work standard of 20 Noi complete understanding of dose-effect tical) microscopy. Although evidence mppcf for talc. -This is an error which fror relationships. Moreover, even though about their toxic effects is still not well should be rectified. Otherwise, the 20 talc different forms of asbestos appear to understood, certain chrysotile, mppcf applies as the US Federal Stand dre- have different toxic effects, a single TLV crocidolite, and other asbestos fibers are ard for both platy and fibrous talc. of was established for all forms because of too short and/or fine to be detected ex seai incomplete information about these dif cept by electron microscopy. Essentially elec ferences.13 the same can be said of chrysotile Environmental Exposures to Talc une I In June 1972, a similarly documented fibrils-- ultramicroscopic morphological T a lc is e c o lo g ic a lly v irtu a lly dee but lower Time-Weighted Average units of a chrysotile fiber mentioned in ubiquitous through its many uses in prlr (TWA) of two such fibers-- proposed the section on Environmental Exposures modern living. Only very recently has vie; Electronphotomicrographs of particles extracted from talc-coated rice. Left: the: Talc (T ) and Amphibole asbestos (A) fibers. Right Talc fiber (T ) with par Chrysotile asbestos fibril (C ). Identification confirmed with selected area dif fraction. (Electron microscopic studies by Dr. A. M. Langer, New York. Original magnification X 45,000.) I dar Ade fou I ova wltl mer tick rep I wa: i v i 19 + Sol + U< 94 Talc: A Possible Occupational and Environmental Carcinogen/Blejer and Arlon Jour there been some indication of its widespread environmental inhalation and other exposures to humans. As reported in 1972, Langer et al16 set out through electron microscopy to identify asbestos materials in the lungs of 28 consecutive autopsy cases of New York City residents. Asbestos bodies were found in only three cases, whereas chrysotile fibers were present in 24. Moreover, chrysotile fibrils were found in all 28 cases. In addition, clay and/or talc particles were identified in the lungs of 18 of these 28 decedents, all of whom had been long-time residents of that city None had been asbestos workers nor, * Source. Henderson et a l! ^ from our review of the published data, talc workers. Recently, Henderson et al17 + Particle size range. 1000 A = 5 urn 4 Same patient drew attention to the close association of talc and asbestos minerals when, searching for asbestos through special electron microscopic techniques, they whether the presence of talc was ad unexpectedly identified talc particles ventitious or causative. deeply imbedded within the tissue of ^ A different study reported in mid-1971 primary ovarian, endometrial and cer- j by the Environm ental Sciences J vical carcinomas. Table 3 summarizes j Laboratory, Mt. Sinai School of these data and also shows that no talc Medicine, The City University of New particles were found in the one secon- i York, revealed that significant amounts dary ovarian carcinoma thus studied. 1 of asbestos were present in two brands Additionally, the same investigators \ of commercial, household-use fibrous found talc particles also in "normal" \ talc dusting ("talcum") powder. As a ovarian tissues removed from patients | result, the US Food and Drug Ad with breast cancer. They made no com- i ministration announced that if such ment, however, as to how the talc par- j results were to be corroborated by an in tides reached the ovaries and other , dependent expert panel, it would ask the reproductive tissues in which the talc ! manufacturers to recall such "talcum was found; nor did they comment as to I v. powders. It is of interest that in dependent geologists informed the FDA that talc and asbestos can appear in the Table 4. -- Talc Used; and Sold or Usi 1959-1963 same mines, and that contamination could be caused at that source.18 19 Uses of Talc G en e ral. -- Talc is found in cosmetics; spray and dusting powder, including "talcum"; chalks and crayons; ceramics; electric and heating insulating materials; roofing materials; insecticides; foundry facings; textiles; white shoe polishes and glove cleaners. Talc is also used as pigment in paints, varnishes, and rubber; filler for asphalt, paper, rubber, plastic, and soap; dusting powder in rubber manufacturing, and products such as inflatable toy ballons, prophylac tic condoms, and contraceptive diaphragms.1 10 In Foods and Drugs. -- Talc also en ters into food processing and phar maceuticals. It is used as an excipient and filler for pills and tablets; for dusting tablet molds; in clarifying liquids by in s e c tic id e s ` piper Hoofing ..Toilet Prepara Bn?,. Textiles 1 .Asphalt Filler JrF o u rd r> Facings - Refractories & " , R i c e Coating k^ cns " r Uses " a- * 1963 US consumption: 763 x 10J short tons. + Source: W eils.1 Less than 1 percent 1964-1965. Source: Soil el a l t 1957-1964 for Issei and N isei, 1959-1961 for Black and While. Source- Dunn and Buell. 4 Foreign born Japanese. US-born Japanese. Journal of Occupational Medicine/Vol. 15, No. 2/February 1973 filtration; in salami dusting; candy molding; in peanut polishing; and in the coating of polished rice.1 10 Table 4 presents quantitative data on many of these uses in the United States and California. Talc-Coated Polished Rice As stated above, talcs are used in a multitude of ways which can lead to widespread inhalation, ingestion, and other exposures. One such major use in volving ingestion is that of talc-coating of polished (white) rice. In the United States, and especially in California,20 a significant portion of the polished rice is coated with glucose and talc. This process, which imparts to white rice a pearly, esthetically more at tractive appearance and may also prolong its shelf-life, has to our knowledge, never been traditionally used in the Orient. Currently in Califor nia food stores it is common to see sacks of rice displaying the mandatory warning label that the rice contains added talc and glucose and that it should be washed before cooking. Consequently, we set out to determine whether the talc used in such coated rice contained asbestos and, if so, whether a related asbestos-ingestion exposure existed. New Findings. -- In this regard, early in 1971, using phase-contrast microscopy w e could not identify any asbestos in the residue obtained from washings of uncooked Californiaprocessed talc-coated rice. Later, however, electron microscopic studies using selected area diffraction were done to analyze similar samples of talc-coated rice bought at nearby stores in small quantities (eg, 85 gm for 4 cents) scooped out of large rice sacks and handed over the the clerk in a plain, brown paper bag. Amphibole asbestos fibers and Chrysotile fibrils were iden tified in the mineral residue, as.shown in the Figure. Similar work done by another program of the California State Depart ment of Public Health in Berkeley also identified asbestos in samples of talccoated rice sold locally. At essentially the same time the Environmental Science Laboratory, Mt. Sinai School of Medicine, the City University of New York, extracted the minerals from several samples of talc-coated rice marketed in the West Coast of the United States. Such extracts were prepared from both uncooked and washed, cooked rice samples. Similar analyses revealed that all samples were contaminated with much Amphibole asbestos (A. M. Langer, personal communications, Feb, Mar, Apr 1972). Similar work done at the School of Public Health, University of California, Berkeley, revealed essen tially identical results, even after multiple washings of the rice (). C. Murchio, per sonal communications, Feb, Jul 1972). Discussion of New Findings Regarding the asbestos contamination of California-processed talc-coated rice, our findings and those of others cited above appear to be important for a num ber of reasons. Firstly, talcs have no nutritional value.20 21 Thus, agricultural researchers have tried unsuccessfully to convince the rice-processing industry to substitute talc for other substances with some nutritional value--even though, to our knowledge, these researchers did not know that talcs could be contaminated with asbestos. Secondly, the "Delaney Amendment" to the US Food Additives Act essentially prohibits the use of any food additive substance known to be carcinogenic to man or any animal. Thirdly, the Hawaiian, Italian, Latin American, O kinawan, and Spanish peoples currently prefer the smooth and shiny talc-coated type of white rice, such as the one processed in California. In fact, the Associated Commonwealth of Puerto Rico buys much of this type of rice, and requires that all rice sold there be both enriched and talc-coated.20 Some of the nations cited, as well as others in the Orient where white rice has been a staple for centuries, continue to exp erience w id e ly different agestandardized gastric cancer rates, and none higher than Japan. Moreover, in some European and other nations where rice is not a staple, the pertinent gastric cancer rates are almost as high as in Japan.22 23World-wide, such high gastric cancer experience can, therefore, be ascribed specifically neither to just a habitually large intake of uncoated white rice nor to a habitually large intake of asbestos-contaminated talc-coated rice, as one report in Science did recently.24 Thus far, the one common denominator in gastric cancer throughout the world appears to be a gross nutritional im balance with an intake high in car bohydrate, low in fat and certain vitamins, as well as, in some cases, high in spicy and/or salty additives. For exam ple, the Japanese ingest large amounts of white rice and salty sauces;25 they also have, as a nation, the highest agestandardized gastric cancer mortality and morbidity- rates.22 23 Lastly, for a variety of environmental factors which are not clear but which point to dietary changes, the foreign and US-born Japanese in California are at a much reduced risk from gastric cancer than the Japanese in Japan.26This change is quite evident from the data in Table 5. In the last few years these Californians of Japanese extraction have begun to show a new and marked preference for shortgrain, talc-coated rice.20 Apparently, ex cept for the talc-coating, this is the same rice traditionally and habitually eaten in Japan, since most of the Californiaproduced rice is of the ;aponica variety of Oryza sativa.20 21 Given the possibility that the ingestion of enough asbestoscontaminated talc were to be car cinogenic, the question arises, therefore, whether the Japanese-Americans might not be adding to their risk of gastric and other gastrointestinal cancers26from their new and increasing ingestion of enough asbestos-contaminated talc-coated rice, thereby counteracting the gastric cancerreducing factors in their new en vironment? Similarly, might other cited nations and peoples who now also prefer talc-coated rice be at a similarly greater risk? If this were so, and con sidering the long lapse-time for the car cinogenic effects of asbestos to become manifest, it would take years, maybe decades, to find conclusive answers. In any case, talc has no known nutritional value. As such, its use as a food and drug additive is questionable, at least, and unwarranted if these talcs are con taminated with asbestos. General Conclusions and Summary Talcs can be contaminated with . asbestos minerals. Both talc and asbestos produce various fibrosing conditions. Asbestos as well as asbestos-con taminated talc are known to be oc cupationally associated with excess mor tality from various cancers. Talc enters into our lives through e v e r y d a y - u s e items. Ingestion, inhalation, skin, vaginal, and other routes of talc ex posure and absorption might, therefore, be associated w ith increased en- 96 Talc: A Possible Occupational and Environmental Carcinogen/Blejer and Arlon vironmental and consumer health risks. Environmentally produced deposition and retention of talc particles in human lungs appear to be widespread Also, talc particles have been found in some normal ovaries, as in the core of primary cancers of the ovary, endometrium, and cervix of nonoccupationally talc- or asbestos-exposed women in Britain. Nevertheless, the presence of talc in these tissues cannot presently be said to be more than adventitious, and a finding w hose significance must aw ait corroboration by well-controlled studies, preferably from diverse geographical areas. Moreover, many talc dusting ("talcu m ") powders and Californiaprocessed talc-coated rices recently tested were found to contain significant amounts of asbestos. Such findings raise questions of possible world-wide in creased health risks to humans, arising from occupational and environmental exposures to those every-day use cosmetics, foods, drugs, and other products which contain talcs signifi cantly contaminated with asbestos. It is not the intent here to imply that all forms of talc pose an occupational or environm ental carcinogenic risk, although there are obvious instances in which certain talcs can be a source of asbestos exposure. The data presented here indicate that whenever talc ex posures are expected to occur, adequate analyses be done beforehand to deter mine that mineral's type and purity, as well as the related need for proper oc cupational and environmental controls. This approach is warranted because, in our experience, many exposed em ployees and consumers at large consider working with or using talc-containing materials essentially safe, which has not been the universal occupational ex perience. Although there is no scientific evidence of any carcinogenicity of talc per se, we would be remiss if we did not suggest a need for feasible, properly con trolled experimental animal exposure studies to ascertain any possible car cinogenicity of pure talc. The authors thank Drs. A. M. Langer and I, I Selikoff, Mt Sinai School of Medicine, New York, for their constructive comments and assistance; Ms. Marilyn Hunter and the Communication Service C en ter, California Department of Public Health, Berkeley, for their painstaking work on manuscript preparation; the Reference Staff, Public Health Library, University of California, Berkeley, and Mr. E. Hughes, Medical Librarian, Kaiser Foundation Hospital, Los Angeles, for their indispensible help in researching the literature. References 1. Wells |R; Talc, soapstone, and pyrophyllile, in Mineral Facts and Problems, 1965 ed. US Bureau of Mines, US Govern ment Printing Office, 196S, pp 919-927 2. The United States Pharmacopeia, 18th revision. US Pharmacopeial Convention, Inc, 1965, p 708. 3. World Health Organization Technical Report Series, No 462; Evaluation of Food Additives Geneva, 1971, p 16. 4 Wagner |C, Sleggs CA, Marchand P- Dif fuse pleural mesothelioma and asbestos ex posure in the North Western Cape Province. Brit I Industr Med 17:260-271, 1960. 5. Smith WE, Miller L, Churg I, et aT Mesotheliomas in hamsters following in trapleural injection of asbestos f Mount Sinai Hosp NY 32:1-8, 1965. 6. Selikoff I), Hammond EC, Churg T Mor tality experience of asbestos insulation workers, 1912-1971. Presented at the IV In ternational Conference on Pneumonconiosis, Bucharest, Sept 29, 1971 7. Selikoff I), Hammond EC, Churg i: Asbestos exposure, smoking, and neoplasia. IAMA 204:106-112, 1968. 8 Wagner |C: Current opinions on the asbestos cancer problem. Ann O ccup Hyg 15:61-64, 1972. 9. Kleinfeld M, Messite I, Kooyman O , et al. Mortality among talc miners and millers tn New York State. Arch Environ Health 14:663 667, 1967. 10. Merck Index, ed 8. 1968, p 1011. 11. Hopkins GB, Taylor GD. Pulmonary talc granulomatosis. Amer Rev Resp Dis 101.104, 1970. 12. American Conference of Governmental Industrial Hygienists Threshold Limit Values of Airborne Contaminants and Physical Agents with Intended Changes Adopted by ACCIH for 1972. Cincinnati, 1972 13. American Conference of Governmental Industrial Hygienists- Documentation of the Threshold Limit Values lor Substances in Workroom Air, ed 3. Cincinnati, 1971. 14. US Office of the Federal Register- O c cupational safety and health standards. Title 29 -- Labor, Chap XVII, Section 1910.93a, as of June 7, 1972, p 11230. 15 US Office of the Federal Register: Table G-3 -- Mineral Dusts, Section 1910.93, 1972, p 11230. 16. Langer AM, Selikoff I), Sastre A. Chrysotile asbestos in the lungs of persons in New York City. Arch Environ Health 22:348 361, 1971. 17. Henderson WJ, Joslin CAF, Turnbull AC, el al: Talc and carcinoma of the ovary and cervix. I Obstet Cynaec Brit Comm 78:266 272, 1971. 18. Trade and government memos, in F-D-C Reports 33 1, July 12, 1971. 19. Trade and government memos, in F-D-C Reports 33:12, July 19, 1971. 20. Ferrel RE, Kohler GO, Mickus RR: New rice coating materials. Rice / 69:11, 1966. 21. Houston DF, Kohler GO : Nutritional Properties of Rice Washington, National Academy of Sciences, 1970, 22. Segi M, Kurihara M, Matsuyama T: Can cer Mortality For Selected Sites in Twenty-four Countries, No. 5 (1964-1965). Sendai, lapan, Dept of Public Health, Tohoku University School of Medicine, 1969. 23. Doll R, Payne P, Waterhouse I (eds) Cancer Incidence in Five Continents. A Technical Report International Union Against O n ce r, Berlin, Springer-Verlag, 1970, vol 2. 24. Merliss RR: Talc-treated rice and lapanese stomach cancer. Science 173.1141 1142, 1971. 25. Wynder EL, Kmet I, Dungal N, et al: An epidemiological investigation of gastric can cer. Cancer 16:1461-1496, 1963. 26. Dunn |E Jr, Buell PE: Gastro-intestmal cancer among the ethnic groups in California. Epidemiology of Gastrointestinal Cancer Sym posium, Proceedings of the Third World Congress of Gastroenterology. Recent Ad vances in Gastroenterology 1:35-47, 1967. Journal of Occupational Medicine/Vol. 15, No. 2/February 1973 97