Document 71Z0YZ51LZK95qgq4r3Q7vrvB

FILE NAME: Talc (TALC) DATE: 1971 Sept DOC#: TALC120 DOCUMENT DESCRIPTION: Medical Journal Article - Talc-Treated Rice and Japanese Stomach Cancer tract appears to be a macromolecule with a mass of approximately 30,000 to 50,000 daltons; it is thermolabile and destroyed by trypsin. It is appar ently not stable on long-term storage, even in the cold. J ohn C. H ouck, H il t je I rausquin Sa n fo r d L e ik in Research Foundation of the Children's Hospital of the District of Columbia, Washington, D.C. 20009, and George Washington University School of Medicine, Washington, D.C. 20005 References and Notes 1 W. Bullough and E. Laurence, Proc. Roy. Soc. Lo n d o n Ser. B 151, 517 (1960); E xp. Cell Res. 33, 176 (1964); N ature 220, 134 (1958). 2 . --------, Eur. J. Cancer 4, 607 (1968). 3. J. R ytom aa and K . Kiviniemi, Cell Tissue K inet. 1, 329 (1968). 4. J. Sim nett and D . C hopra, N ature 222, 1189 ( 1969). 5. M . V oaden, E xp. E ye Rse. 7, 326 (1968). 6. J. M oorhead, E. Paraskova-Tchernozem ska, A. Pirrie, S. H ayes, N ature 224, 1207 (1969). 7. E. Zipilivan, B. Hudson, W. Blatt, Anal. Bto- ' ciiem. 30, 91 (1969). 8. Supported in p art by a contract from the M edicine and D entistry D ivision of the Office of Naval Research. 24 M ay 1971 Talc-Treated Rice and Japanese Stomach Cancer Abstract. The Japanese prefer talc-dusted rice in their diet. The incidence of stomach cancer in Japan is unusually high. Most talc has some asbestos con taminants. Epidemiologic evidence is presented that the asbestos-contaminated talc on rice in the diet is the carcinogen or cocarcinogen responsible for the high incidence of Japanese stomach cancer. The high incidence of stomach can cer in Japanese men represents a chal lenging problem in cancer epidemiol ogy. Study of age-adjusted rates of mortality from stomach cancer in 24 countries showed that from 1962 to 1963 Japanese men had the highest rate for all nations; the rate, 67.96 per 100,000 in the male population, was seven times that for men in the United States (7). Since talc frequently con tains asbestos (2), and since workmen exposed to asbestos show a marked increase in gastrointestinal cancer, es pecially stomach cancer (3), the hy pothesis that the increased rate of cancer of the stomach in Japan is due to ingestion of rice contaminated with asbestos seems attractive and has been recently suggested in a brief note (4). This report presents evidence for this relationship at somewhat greater length. Rice grown in California and meant for the American consumer is milled mechanically. Rice is prepared differ ently for the Japanese consumer. It is milled and treated with glucose, and then talc is added. The talc is held to the surface of the grain and is said to preserve its flavor better. Japanese con sider this rice more tasty, both here and in Japan. Two percent of all talc produced in California from 1959 to 1963 was used as a rice additive, pri m arily fo r export to Japan (5). Rice containers in Los Angeles markets in tended for the Japanese customer usu ally bear the legend: "Coated with glucose and talc." Optical microscopy of the ash of such store-bought rice 17 SE PTE M B E R 1971 showed 3.7 X 10 asbestos-form fibers per gram (Fig. 1). Talc, the mineral, is a hydrous sili 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 structure, asbestos being fibrous and mineral, talc being flaky or granular. However, commercial talc is composed not only of the pure mineral talc, but also of fibrous silicates, which are in part classifiable as asbestos. There is Fig. 1. Photomicrograph of the ash of a specimen of rice intended for Japanese consmnption and purchased in a Los Angeles market. Arrows indicate asbestosform fibers. The specimen contained 3.7 X 10* such fibers per gram. no firm mineralogic definition of com 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 platy or granular type of mineral relatively free of asbestos minerals (6). New York and California talcs contain more fibrous silicates, including anthophyllite and tremolite (2, 5). Respired asbestos and talc dust cause similar disorders in workmen. Older talc workers show more than four times the expected incidence of lung and pleural cancer (7). Talc or talcose minerals, including contaminating as bestos, are apparently the responsible carcinogens since, where confirmatory evidence could be obtained, all those talc workers with pleural and lung cancer also had talc pneumoconiosis. Autopsies on six talc workers with talc pneumoconiosis showed the presence of the characteristic "asbestos body" in the lungs of every one (8). When talc is examined by phase contrast microscopy, from 8 to 30 percent of the particles are fibrous silicates. Identifiable tremolite, anthophyllite, and chrysotile are also seen (9). The large talc deposits of New York and Cali fornia regularly contain the amphibole asbestos minerals, tremolite and antho phyllite. These are normal ingredients of commercial talcs from these areas. Chrysotile asbestos occurs in veins in talcose mineral deposits and may be then mined with the talc and create a contaminant (9). Asbestos is an established carcinogen. Not only does it cause lung cancer, but it is associated with a substantial in crease of morbidity from stomach can cer (3). Although chrysotile is the most important commercial fiber of asbestos, there is no reason to regard the amphi bole asbestos minerals as safe. To the contrary in one study an amphibole asbestos mineral predominated in as bestos-bodies in the sputum of a group of men exposed to asbestos and having a high incidence of mesotheliomata {10). The fact that talc workers exposed to fibrous talc, which contains amphi bole asbestos, develop more pulmonary injury than do workers exposed only to talcs relatively free of fibrous silicates or amphiboles {ID, indicates the patho genicity of amphibole asbestos. The Japanese preference for talccoated rice means that rice eaters of that nation are exposed to the hazard of ingestion of amphibole asbestos, as 1141 well as the unpredictable ingestion of chrysotile in areas where talc contains these carcinogenic materials. Examination of the known epidemio logic characteristics of stomach cancer in Japanese strongly suggests that the causative agent is an additive to rice. Not only is the incidence of stomach cancer high in rice-eating Japanese, but inside Japan stomach cancer is most prevalent in those prefectures where rice is the main staple; it is less so in prefectures where rice is supplemented with cereal (12) and where the popula tion eats heavily of the soybean prepa rations shoyo and miso (13). 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 (14). Experimental consumption of polished rice will cause ulceropapillomata of the forestomach of rats (15). These observations suggest a relation ship between rice consumption and stomach cancer. However, the agent is not the rice itself, since in other oriental countries where talc-coated rice is not popular the incidence of stomach can cer is not unduly high. A final indication of the environ mental causes of stomach cancer in Japanese is provided by statistics con cerning its prevalence in Japanese im migrants to western countries. The incidence in Japanese males in Japan in 1962 to 1964 was 77.9 per 100,000 (16). Japanese men in Hawaii had an incidence of only 45 per 100,000. Even this lowered rate was high com pared to that for Chinese and Cauca sian men of Hawaii who had incidences of 9.2 and 8.3, respectively. Native born Japanese have a higher incidence of stomach cancer than Japanese bom in Hawaii or continental North Amer ica (17). Dietetic studies on immi grant Japanese show that from 50 to 70 percent of their diet is Japanese type food (18). The longer the immi grant has been in the West the more western his diet becomes; this increase in western food in the diet coincides 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, standardized mortality rates are also high for Chile, Finland, and Iceland, where rice is not 1142 a major dietary staple (12,19). In view of the evidence for the 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 are needed. R. R. M erliss 8820 Wilshire Boulevard, Beverly Hills, California 90211 References and Notes 1. T. Hirohata and M . Kuratsume, Br. 3. Can cer, 23, 465 (1969). 2. L. A . Wright, Talc and Soapstone (California Division of M ines Publications, Bulletin 176, San Francisco, 1957). 3. I. Selikoff, J. Churg, E. Hammond, / . Am . M ed. Assoc. 188, 22 (1964). 4. R. Merliss, ibid. 216, 2144 (1971). 5. J. R. Wells, in Mineral Facts and Problems (U.S. Bureau o f Mines, Washington, D.C., 1965). 6. B. W eiss and E. Bochncr, Arch. Environ. Health 14, 304 (1967). 7. M . Kleinfeld, J. Messite, O. Kooyman, M. Zaki, ibid., p. 663. 8. M. Kleinfeld, C. G lel, J. Majeranowsld, J. Messite, ibid. 7, 101 (1963). 9. L. Cralley, M . Key, D . Groth, W . Lainhart, R. Ligo, Am. Ind. Hyg. Assoc. 3. 29, 350 (1968). 10. J. Stumphuis and P. Meyer, A nn. Occup. Hyg. 11, 283 (1968). 11. J. M essite, G . Reddin, M . Kleinfeld, A m . Med. Assoc. Arch. Ind. Health 20. 408 (1959). 12. M. Segi and M. Kurihara, Tohuku J. Exp. M ed. 72, 169 (1960). 13. M . Segi, L. Fukushima, S. Fujisaku, M . Kurihara, S. Salto, K. Asano, M . Kamoi, Gann 48 (Suppl.), 1063 (1957). 14. I. Hirayama, in Proceedings o f the Interna tional Conference on Gastric Cancer (Maruzen, Tokyo, 1968). 15. A . Braunschwig and R , A . Rasmussen, Can cer Res. 1, 371 (1941). 16. R. D oll, P. Payne, J. Waterhouse, Cancer Incidence in Five Continents (Springer-Ver lag, N ew York, 1966). 17. W . B. Quisenberry, Acta Vnio Int. Contra Cancrum 17, 858 (1961). 18. W. MacDonald, Canadian Cancer Confer ence 6th (1966), pp. 451-459. 19. N . Dungal and J. Sigurjonsson, Br. 3. Can cer 21, 270 (1967), 7 June 1971 m Cyclic Adenosine Monophosphate in Brain Areas: Microwave Irradiation as a Means of Tissue Fixation Abstract. Amounts of cyclic adenosine monophosphate in discrete regions of the brain were estimated after exposure of rats to microwave irradiation. Amounts were highest in the cerebellum and brainstem, intermediate in the hypothalamus and midbrain, and lowest in the hippocampus and cortex. Decapitation increased the concentration of cyclic adenosine monophosphate in all brain areas, although the increase in the cerebellum was three to four times greater than that in other areas. Microwave irradiation may provide a means of rapidly fixing brain tissue in situ while permitting easy dissection of the brain. In this way artifacts produced by decapitation can be eliminated, and concentrations of heat-stable compounds in the brain can be estimated under conditions which more closely approximate those in vivo. Rapid fixation of cerebral tissue in situ is required to obtain valid estimates of many brain components. Decapita tion and delayed fixation lead to signifi cant changes in brain glycogen (1) and in glucose, lactic acid (2), and other sub strates and cofactors of the EmbdenMeyerhof pathway (3). At present fix ation of the brain in situ is carried out by freezing whole animals in liquid ni trogen or cooled isopentane. Even under such conditions, deep brain structures Tabic 1. Amounts of cyclic AMP in brain areas after microwave irradiation. Values re present the mean and standard error of the mean from six separate determinations. Area C(yncmlioclAe/Mg)P Cerebellum Brainstem Hypothalamus Midbrain Hippocampus Cortex 1.86 0.06 1.87 0.06 . 1.60 0.04 1.43 0.11 0.84 0.09 0.74 0.06 can require up to 75 seconds to reach 0C (4). These freezing techniques also require restraint of the animal and pro duce considerable stress before it dies. Dissection of the frozen brain is almost impossible, and therefore experiments must be done on whole brains. These problems have prevented the measure ment of cyclic adenosine monophos phate (AMP) in discrete brain regions. Drug-induced changes in concentrations of cyclic AMP in specific brain areas might easily be masked by massive amounts of unresponding tissue when nucleotide concentrations are measured in the frozen whole brain. Furthermore, the concentration of cyclic AMP in the whole brain increases severalfold with in seconds after decapitation thereby prohibiting rapid dissection after death (5). Stavinoha (6) reported that amounts of acetylcholine in the brains of rats that had been killed by being exposed to microwave irradiation were signifi cantly higher than previously reported. SCIENCE, VOL. 173 I c\1!