Document 79DnpqvxBk1YBa7E312Bnxxe

FILE NAME: Oil Industry and American Petroleum Institute (API) DATE: 1945-1950 DOC#: API019 DOCUMENT DESCRIPTION: API History of the Subcommittee on Carcinogenicity UBAfl* 4Iti RICAN PHRUltUM iNSTilW I . I API HISTORY OF THE ' SUBCOMMITTEE " ON t CARCINOGENICITY 19^5-1950 i -It'S For x-uormation Only - Not for Publication A contribution of information to Members of API Medical Advisory Committee. ________________ 6-13-45. attention Mr. P. V. Keyser, Jr. Dr. A. A. O'Kelly Dr. W. P. Hawthorne Technical Memo No. 45-214 Chemical Division Socony-Vacuum Oil Co., Inc. Research and Development Laboratories Paulsboro, New Jersey April 27, 1945 Carcinogenic Hydrocarbons, Literature Survey A brief literature survey of the cancer-producing hydrocarbons has been made as requested by Dr. L. C. Beard in his letter (W. M. Holaday/ F. V. Keyser, Jr.) of April 12, 1945. Carcinogenic activity has been noted in various types of compounds including hydrocarbons, amino, azo and nitro compounds, hormones, and in organic compounds. This report will be confined to the hydrocarbons and hydrocarbon fractions identified as carcinogenic. Most of the carcinogenic hydrocarbons were originally identified in the pyrolysis products of coal, wood, petroleum and shale. In some cases these hydrocarbons exist, as such, in the original materials. The active hydrocarbons are almost without exception polynuclear aromatic hydrocarbons and are conveniently classified under the parent hydrocarbons from which they might be derived. Thus, the three main types are classified as benzopyrenes, cholanthrenes, and benzanthracenes. Identified Carcinogenic Hydrocarbons (7),(22).(45),(24), (12),(10),(5),(28), (29),(38),(47) I. Benzopyrenes 1 ,2-benzopyrene 3,4-benzopyrene 1,2,3,4, dibenzopyrene I I . Cholant hrene s cholanthrene 20--methyl cholanthrene 16,20-dimethyl cholanthrene 20-ethyl cholanthrene 1 5 ,16-benzdehydrocholanthrene ) N ' -2- 20-isopropyl cholanthrene 3-methyl cholanthrene meso-dihydro cholanthrene A-raethyl cholanthrene 5-raethyl cholanthrene meso-dihydro 3-mothyl 1-ketochoianthrene cholanthrene III. Benzanthracenes 1 ,2-benzanthracene 10-methyl-l,2-benzanthracene 9-methyl-1 ,2-benzanthracene 5,10-dimethyl-l,2-benzanthracene 5.9- dimothyl 1 ,2-benzanthracene 8.9- dimethyl 1 ,2- benzanthracene A,10-ace 1,2-benzanthracene 9.10- dimethyl 1 ,2-benzanthracene 8.10- ace 1 ,2-benzanthracene 10 ethyl 1 ,2-benzanthracene 5 methyl 1 ,2-benzanthracene 5 n-propyl 1 ,2-benzanthracene 6 methyl 1 ,2-benzanthracene 5.6 dimethyl 1 ,2-benzanthrr.cene 6 isopropyl 1 ,2-benzanthracene 6.7 cyclopenteno-1,2 benzanthracene 3 hydroxy-1,2-benzanthracene 3 methoxy-1 ,2-benzanthracene 5 propyl-9,10 dimethyl-1,2 benzanthracene 5 ethyl-9,10 dimethyl -1,2 benzanthracene 5 methyl-7,8 dihydro-1,2 benzanthracene 1 .2 .5.6 dibenzanthracene l ',9 methylene-1 ,2,5,6 dibenzanthracene tetrahydro-1,2 benzanthracene 5.6 cyclopenteno-1,2 benzanthracene IV. Miscellaneous sym. triphenyl benzene tetra-phenyl methane o-amino-azotoluene 9,10 dimethyl anthracene 1 ,2 cyclopenteno-510-aceanthrene The Nature of Petroleum Carcinogens The probability that the carcinogenic hydrocarbons in petroleum are of the same nature as those listed above has been indicated by various workers. Roffo (A3) found that the fractions of fuel oil boiling between 270-300C, and 300-330C, produced tumors in eighty percent of the rabbits to whose skin these fractions were applied, and the absorption spectra of these fractions were similar to thee of known cancer-producing compounds. Spectrograph!c analysis of distillates of all fuel oils tested showed the presence of the same class of hydrocarbons. Twort and Fulton (59) 3tate that oils with a preponderance of paraffins have relatively little -3- carcinogenic activity, but that carcinogenesis is high in oils with a preponderance of isocyclic compounds, Pessano (41) found that some of the products of combustion in gasoline engines are in the group considered carcinogenic. Eats respiring the products of combustion of fuel oil at high concentration developed carcinoma of the lungs. The liquid products formed by combustion of petroleum, when applied to the skin of rabbits, produced malignant tumors. A substance containing the benzo (o<) pyrene nucleus, with decidedly cancorogenic properties, has been isolated (32) from tar such as is used in paving roads. The prevalence of cancer among paraffin workers has been shown (63) to be due to irritating impurities- present in the crude paraffin wax. The pure paraffin (C,,.H,,) has been tested and found to be non-carcinogenic. 24 50 The Most Carcinogenic Petroleum Fractions Carcinogenic hydrocarbons have been shown to be more or less concentrated in certain fractions of petroleum. In general, the higher boiling fractions (fuel oil, lubricating oil, tar, etc.) contain more carcinogenic hydrocarbons than the lower fractions. Two petroleum oils used in cotton spinning mills yielded high boiling fractions 31 times as carcinogenic as the low boiling fractions (58). The heavier grade lubricating oils are said to be less potent than the spindle oils (54). Shale oil was found (58) to be about 12 times as carcinogenic as petroleum-well oils; the most potent shale oil fraction being the unfinished lubricating oil from which most of the paraffin wax has been removed but which has not been treat ed with sulfuric acid or filtered (54). Wood (62) found that while mineral oil of the type used therapeutically was not carcinogenic, heavy lubricating oils did show some carcinogenicity, and tar showed the same property to a larger degree. Twort and Lyth (60) investigated a range of commercial distillates of a topped Borneo crude oil. They found that the peak carcinogenic activity was associated with the fraction having a viscosity of 200-225 centipoises at 25C, and that the whole range of oils showed biological activity. This activity had been predicted from an examination of the physical properties of the oils which were alone sufficient to condemn their use as lubricants when likely to come into contact with the user. Evidence of the presence of carcinogens in cracked mineral oil was noted (56) in an investigation of the oily, tarry material extracted from the soot of the expansion chamber of a high-compression, internal-combustion engine. This material was highly carcinogenic to the skin of mice. In general, the carcinogenic potency of crude shale oils decreased as the cracking temperature wab lowered but was still present at 400Centigrade. These investigators also found that a heavy grade of Diesel fuel oil was carcinogenic but that a light grade oil was not. Effect of Treatment of Oils on Carcinogenicity Vioodhouse (64) found that the petroleum ether extract of pitch and the SO2 extract of spindle oil distillate from a paraffin-base crude w=re carcinogenic, Lyth (36) noted, during careful fractionation of -4- Scottish shale oil and a Persian oil, that all samples of petroleum oil which were treated with ethanol provided residues of lower carcinogenicity and higher refractive index and density than the original oil. Twort and Fulton (59) found that saturation by oxidation and reduction cr treatment by silica gels or clay reduced the cancerogenic activity of their mineral oils probably through adsorption and polymerization. Alcohol extraction and sulfuric acid treatment reduced the carcinogenicity of the oils by extracting the carcinogens. The same authors also found that the active agents could be concentrated by extraction with methyl sulfite or methyl suil'ate and picric acid. They suggested the process for treating oil for industrial use. Relation of Carcinogenicity to Fluorescence and Chemical and Physical Properties Twort and Twcrt (54) found that the cancer-producing properties of mineral oils appeared to. be related to their flueroscence; oils having a blue fluorescence seemed more a.ctive than those having a green fluorescence. Weiss (61) noted that strong fluorescence was almost confined to conjugated ring systems which possessed highly mobile electrons. Only the more symmetrically conjugated systems cr those which do net give rise to strongly ionic structures show fluorescence. The author compared the mobile electrons with metallic electrons and stated that carcinogenic hydrocarbons belong to ' this group of hydrocarbons. .Hieger (26) found that the fluorescence spectra of many carcinogenic substances show bands at wave lengths cf 4000, 4180, and 4400Ac . These bands are similar to those cf the spectra of 1,2-benzanthracene, a known carcinogen of high potency. A relationship between physical properties and carcinogenicity was observed by Lyth (35) who stated that oils with a refractive index less than 1.5500 were non-toxic while oils with an index exceeding 1.5600 were highly toxic; Pennsylvania oils and certain mildly treated oils were an exception. The same author noted a relationship between the iodine value of untreated oils and carcinogenicity. Toxicity increased in the same order as the iodine value, Pennsylvania oils again excepted. Fieser and Hershberg (21) found that the behavior of polynuclear hydrocarbons in lead acetate oxidation, aldehyde reaction, and diazo-coupling indicated that the most carcinogenic hydrocarbons of the series tested ' possessed special susceptibility to substitution, Schmidt (48) discussed the theory of the box model of aromatic compounds and stated that the theory is especially successful in character izing the cancer-producing hydrocarbons as compounds with abnormally high electrogen density and low excitation energy. Other references relating structure and physical and chemical properties to carcinogenicity include Bradley (8); Clar (12); Dunlap and Warren (18); Fieser (19) and (20); Fieser and Campbell (22); Iball (28); Kennaway et al., (29); Lundgren (34); Shear et al,, (51); and Truhaut (53). More general references to known carcinogens, including reviews of the literature up to the date of the reference, are Addiaall (1); Andervont (2); Barry (3); Blanc (A); Boyland (5) id (6); Brady (9); Bruce and Kahn (10); Butenandt (11); Cook (13) and (14); Cook et al., (16); Cook and Kennaway (15) and (17); Hartwell (24); Kewett (25); Kernack (30); API 04612 - 5- Kirby^(3l); Morton et al., (39); Roffo (42); Rondoni (44); Sampey (45); S?.nnie and Truhaut (46); Sasaki and Yoshida (47)J Schurch (49); Shabad (50); and Siboni (52). The greater part of the original references were unavailable and so were quoted directly from chemical abstracts. For these references the chemical abstract reference is listed in parentheses after the original reference in the bibliography. LJH:RMW /a/ L. J. Hillenbrand L. J. Hillenbrand BIBLIOGRAPHY .1 . Addinall, C. R., Merck Report 44, 16-18(1935) (C.A.29,6203^) 2 Andorvont, H. B., Univ. Wisconsin, Symposium on Cancer Sept. 1936, 54-66 (C.A.32,3812) 3. Barry, G., et al., Proc. Roy. Soc. B117, 318-51(1935) (C.A.29,51873) 4. Blanc, Thesis for degree Dr. of Pharmacy, Besancon 1936 (C.A.31.1583) 5. Boyland, E., Nature 130, 274-5(1932) (C.A.26,55813) 6. Boyland, E, Am. Rev. Bicchem. 4,469-78(1935) (C.a .2^,51803) 7. Bradbury, J. T., et al., Cancer Research 1, 635-94(1941) (C.A.35.8055') 3. Bradley, U., Nature 137, 404-5(1936) (C.aT 30,38783) 9. Brady, 0. L., Science Progress 28, 100-7(1933) (C.A.27,4217^) 10. Bruce, Vi. F., and Kahn, S. J., J. Am. Chem. Soc. 60,~T017-19 (1938) (C.A.32,49796 ) 11. 3utenandt, a ., *rch. exptl. path, pharm. 190, 74-91(1938) (C.A.^3.7372) 12. Cl.ar, E., ..romatische Kohlenwasserstoffe, Polycyclische Systme, 65-73, Berlin, Springer-Verlag 1941 13. Cook, J. Vi., Yale J. Biol. Med. L L , 1-13(1938) (C.h -22,221 9) 14. Cook, J. Vi., Nature 145. 335-8(1940) . 15. Cook, J. W . , and Kennaway, E. L., Am. J. Cancer 33 , 50-97(1938) (C.A.32,67313) 4 16. Cock, J. Vi., et al., Am. J. Cancer 29, 219-59(1937) (C.a . 31,3982s) 17. Cook, J. Vi., and Kennaway, E. L., Am. J. Cancer 39, 381-428, 521-32(1940) (C.A.35,13532 ) 18. Dunlap, C. E., and Warren, S., Cancer Research 1, 953-4(1941) (0.4.^6,10825) " ' - .19. 20 Fieser, L. F., Am. J. Cancer 4, 37-124(1938) (C.A.22,1387s) Fieser, L. F., Univ. Penna. Bicentennial Ccnf. on Cause and Growth of Cancer 1941, l-27(C.A.35,8072s) .21, 22 Fioser, L. F . , a n d Ilershberg, E. B., J. Am. Chem. Soc. 60, 2542-8(1938) Fieser, L. F., and Campbell, Vi. P., J. Am. Chem. Soc. 60, 1142-5(1938) 23. Haddow, A., and Robinson, A. M , , Proc. Roy. Soc. B127. 227-87(1939) (C.A.33,6428^) 24. Hartwell, J. L., Nat. Cancer. Inst,, U. S. Public Health Service (1941) 25. Hewett, C. L., Current Science 527-30(1937) (C.A.^1,5036^) Hieger, I., Biochem. J. 24, 505-11(1930) (C.A.2^,53691 ) Hirst, H. R., and King, A. T., Nature 130. 578 and 810(1932) Iball, J., Z. Krist. 9^, 7-21(1936) (C.A.^0,7412s) Kennaway, E. L., et al., Cancer Research 2, 157-9(1942) (C.a .35,32502 ) 30. Kermack, Vi. 0., Science Progress 28, 115-23(1933) (C.A.27,425o3) 31. Kirby, a . H. M., Nature 154. 668-9(1944) (C.A.^9,9769) 32. Kling, A., at al., Bull. Acad. Med. 120, 130-43(1938) (C.A.^3,87795) 33. Luden, G., Can. Med. assoc. J. 17, 43-8 (1927) (C.A. 21, 956^) 34. Lundgreri, H. P., Science 82, 130-3 (1935) (C.A. 29, 66117) 35. Lyth, R., J. Ind. Hyg. 15 M * 226-37 (1933) (C.A. 27, 51103) 36. Lyth, R., Nature 139. 374 (1937) (C.A. 1, 40993 ) 37. Lyth, R., and Twort, C.C., J. Hyg. 8, 269-72 (1938) (C.A. 32, 6323) 38. Morton, A. A., et al., Science 82, 134 (1935) (C.A. 29, 6642) 39. Merten, A. A., et al., Am. J. Cancer, 26, 755-60 (1936) (C.A. ,22, 5291^) a .40. Nyrcp, J. E., Prctcplasma 294-300 (1932) (C.A. 27, 29932 ) Pessano, J. E., Semana Med. (Buenos Aires) 1942 II, 210-14 (C.A. 21> s776 ) 42. Roffo, A. H., Necplasmes 11, 77-89 (1932) (C.A. 26, 51452 ) 43. Rcffo, ... H., Bel. Inst. Med. Exptl. Estud. Cancer 17, 385-414 (1940) (C.A. 35, 14992 ) , 44. Rondcni, P . , Chimica e Industria (Italy) 17, 148-54 (1935) (C.A. 29, 5176) (BIBLIOGRAPHY - CONTINUED) 45 Sampoy, J. R., Cher.. Ed. 16, 461-6 (1939) 4b. Sarnie, C., and Truhaut, R., Bull, asscc. Fraiie etude Cancer 23, 6-37 (1934) (C.A. 30, 52902) 47. Sasaki, T., and Ycshida, T., Bull. rtsscc. Franc etude Cancer 24, 534-8 (1935) (C.A. 30, 52904) 46. Schmidt, 0., Bor. 73A, 97-116 (1940) 49. Schurch, 0., and Winterstein, A., Z. Physicl. Chem. 2J6, 79-91 (1935) (C.A. 29, 81047) 50. Shaba.i, L. U., Arch. Sci. Biel. (USSR) 9 , 147-68 (1935) ( C. n. 0 , 56449) 51. Shear, M. J., et al., J. Nat. Cancer Inst. 1, 303~36 (C .n . 5, 44752>5) 52. Sibcni, R . , Bell. chia. farm. 74, 709-20 (1935) (C.A. JO, 52B69) 53. Truhaut, R., Chimie et Industrie J9, 419-32 (1938) (C.A. 2, 4652^-) 54. Twcrt, C. C., and Twort, J. a., J. Ind. Hyg. 13, 204-26 (1931) (C.n. 25, 52053) 55. Twcrt, C. C., and Twcrt, J. a., Lancet 19341. 286-7 (C.A. 28, 58783) 56. Twcrt, C. C., and Twcrt, J. a . , Lancet 1935 II, 1226-8 ( C . a . JO, 22555) 57. Twcrt, C. C., and Twort, J. U . , Oil Colour Trades J. 94, 251-5 (1938) .(C.A. 32, 79947 ) 5G. Twort, C. ..(C.A. 23, 59. Twort, C. (C.A. 26, C., and Ing. H. 1972) C,, and Fultcri, 35755) R., Z. J. D., Krebsfcrsch 27, 308-51 (1928) Z Krebeforech 5, 543-73 (1932) 60. Twcrt, J. M., and Lyth, R., J. Hyg. 9, 161-9 (1939) (C.A. JJ, 5G619) 61. Weiss, J., Nature 145, 744-5 (1940) 62. Weed, F. C., J. Am. Med. asscc. 94, 1641-3 (1930) (C.A. 24,48672 ) 63. Wocd, H. B., J. Cancer Research 13, 97-102 (1929) (C.A. 2J, 3272?) 64. Wcodhouse, D. L., J. Inst. Petr. Tech, 20, 1057-63 (1934) (C.A. 29, 12369 ) Fer Information Only - Net for Publication A contribution of information to Members of API Medical Advisory Committee. ________________________ ;__________________ 6-13-45. THE CARCINOGENICITY OF BITUMINOUS COMPOUNDS shhj- Literature Review April 30, 1945 Library of the Technical & Research Division The Texas Company New York City N0T E In view cf the immense amount of published information on various phases cf the cancer problem it should be emphasized that this literature review gives only a rapid survey cf developments in the field of cancer research as applied directly tc the petroleum, cool tar, oil shale and -allied industries. Yihile it is far from being complete, yet it is believed that most of the important work in this particular field has been covered, either in the report itself or in one cf the bibliographical references given in the appendix and referred tc at the bottom of page 1 . M. P. Doss THE CARCINOGENICITY OF BITUMINOUS COMPOUNDS It has long been recognized that the incidence of skin cancer is greater among workers in certain industries and occupations than among the population as a whole. Attention was first directed in 1787 to the very high death rate result ing from scrotal cancer of chimney sweeps; it is eight times more common in these workers than in the general public in England, and in the United States the ratio cf cancer cases in chimney sweeps is double that cf the general population' . In practically all cases it is the scrotum that is attacked} this is also the site in mule spinners cancer discussed later, T'crkers in other industries coming into direct contact with tars, pitches, shale cils, eta. likewise shew a high incidence of skin cancer, for example, laborers in plants making briquettes, tar reefing, wood preservatives, artificial gas, insulating compounds, shale products, etc. However, in spite cf the recognition of the fact that bituminous com pounds were apparently the cause cf skin cancer, it was- net until relatively recently that skin cancer was produced in laboratory animals by direct application cf tar. This was accomplished by the Japanese investigators Yamigawa and Ichikawal22 in 1915 Since then a great deal cf very careful work has been done in synthesizing and testing various organic compounds, particularly polycyclic aydrocarbons and derivatives. For lengthy reviews of this work, see References 8-12, 14, 17 , 20, 22, 23, 26-29 , 32-34, 74, and 87} particularly the review by J. L. Hartwell cf the National Cancer Institute covering 696 chemical substances, cf which 169 are reported to be carcinogenic^-. L. F. Fieser summarizes cur knowledge in this field as follows^: "As judged by all available data for the production cf skin and subcutaneous tumors in rats and mice, methylshclanthrene probably is the most potent cf the known chemical carcinogens. Systematic studies cf synthetic model compounds have shown that the methyl group is cf nc importance tc the functioning cf the compound; . . 'that much, if net nl 1 of the efficacy of cholanthrene is retained in the analogous hydrocarbon 5,10-dimethyl-l,2-benzanthracene} and that the most significent structural feature cf chclanthrene or methylcholanthrene is the 1 ,2-benzanthracene ring system with a T -2- carbon substituent at the meso position 10, 10-Liethyl-l, 2-benzanthracene evokes sarcomas in mice nearly as rapidly as methylcholanthrene, and, though it is distinctly less effective in the production of skin cancer, the substance constitutes the nearest a.pproach in a simple model compound to a simulation of the biological properties of the hydrocarbon of more complicated structure. "Ail twelve possible monomethyl derivatives of the inactive 1, 2-benzanthracene have been synthesized and tested for carcino genic activity, and of these the 10-isomer is the most potent. The meso-substituted 9-methyl compound stands next in order of potency, followed closely by the 5-methyl derivative, which produced sarcomas in mice with a latent period about twice as long as that observed with 10-methyl-l,2-benzanthracene. Methylcholanthrene and benzpyrene can be regarded as 1, 2-benzanthracenes substituted at the meso positions 10 and 9, respectively, and in model compounds the combination of the two types of substitution is particularly favorable, 9,10-Dimethyl- 1 ,2-benzanthracene produced skin tumors in mice with remarkable rapidity and in this test surpasses methylcholanthrene in speed of action, though it is less effective when administered by subcutaneous injection. The thiophene isologue of the hydro carbon has comparable properties," Numerous attempts have been made to isolate the definite carcinogenic compounds in coal tar by means of distillation, solvent extraction, etc.73# but while very potent fractions have been obtained, the individual compounds have been difficult to separate. Kennaway and Hieger ^ proved the carcinogenicity cf 1 ,2,5,6-dibenzanthracene, the first pure carcinogenic hydrocarbon known. Ccck, Hieger and Hewitt ^ in 1933 isolated 1,2-benzpyrene, 4,5-benzpyrene and 1 ,2-benzanthracene and estimated that the original coal tar pitch contained not 1-.SS than 0.003^ of the potent 1,2-benzpyrene. Several investigators 2 24, 25 have attempted to correlate carcino genesis with fluorescence. For example, the cancer-producing material formed by the action of AlCl^ on tetrahydronaphthalene shows a blue-violet fluorescence, shewing three bands, 4000 , 4180 and 4400 A.U., which are similar to the fluorescence spectrum of 1,2-benzanthracene U*, Kennaway and Hieger &2 suggest the possibility of the use of the fluorescence spectrum for-the preliminary ^tooination of materials suspected of being carcinogenic. API 04619 -3- An important fact brought out by several investigators is that the temperature to which a tar, shale oil or petroleum oil has been subjected determines its carcinogenic activity. In general, it would seem that temperatures up to 500C. are without effect 52 but above that temperature carcinogens are formed, the maximum yield lying between 80C and 900C. 53, 59, Tar and pitch from gas works are far more active than that from coke ovens 58^ accounting for 70$ of all cases of tar cancer in the United States while the coke oven product causes only 5$ ^3. While petroleum residues resulting from moderate heat treatment are inactive ^ <-1, yet by passing an inactive California petroleum through a tube at 380C. Kennaway and Leitch obtained a very active carcinogen 59, 60# Even an inactive medicinal paraffin oil heated to 330C. under 50 atms. pressure acquired some carcinogenic activity 1^1 * Kennaway 56 likewise obtained an active material by passing isoprene through a tube filled with and heated to 820C. Watson H 5 achieved similar results with turpentine at 850C. Acetylene yields an active product on being passed through a red hot tube 59 but it must be pointed out that treatment with AlCl^ at room temperature also produces an active compound 61, On the other hand, synthetic lubricating oils produced by AICI3 polymerization at temperatures up to 150C. were entirely inactive 121. it is suggested that the condensation products of acetylene are of a more complicated nature and probably more unsaturated than those obtained from ethylene. The carcinogenic activity of tars depends apparently not only on the temperatures of their formation but also on the chemical compound used as the base stock 1^, For example, a tar made from pinene at 850C. was far more active than one from turpentine made similarly, the relative potencies being 100:19. Pinene tars made at 500, 600, 750, 850 and 950C. had relative potencies -Ur- cf 0, 12, 2L, 100 and 6k. Oxidation of a synthetic tar at 100C. reduced its potency from 100 to 63, and at 150-l60C. its potency fell to 0. Oxidation with on acetone solution of KlinC^ reduced the potency to 24j with pyridine an a solvent, almost to 0. The active constituents of synthetic tars form crystalline picrates, the remaining filtrate being almost inactive, and the picrate extremely patent. Sh'-le oil is carcinogenic, probably as a result of the high temperatures to which oil shale is subjected However, temperatures below kOOcC. give a relatively inactive product, 500cC. and above being required 101# In England where high temperature tar is used in briquette manufacture, there are many cases cf skin cancer among the workmen, which is not the case in France where the low temperature product is used. The greatest amount c-f investigation cf any type of occupational cancer has been carried out on mule spinners cancer in the cotton mills of Lancashire, England. Scutham and Viilson ^8 n 1922 first called attention the excessive occurrence cf cancer in mule spinners. Women workers are not affected and about 70$ cf all cancer among mule spinners is cf the scrotum apparently due to the fact that a mule spinner at work walks to and fro in front of his machine, leaning over the moving frame from time to time to join up broken ends of the yarn. The base of the frame is on a level with the groin and the spindles on the frame as they rapidly revolve throw off oil from their bearings onto the clothes. In the hot mills the men perspire freely and so wash off the natural grease cf the skin, thus allowing the oil closer contact 3-5# Irritation by the trousers and overalls also helps the process. It is interesting to note that no trouble of this sort was noticed in England until mineral oil replaced animal and vegetable oils as a lubricant 3-6, Henry ^3 estimates that 0,2556 of all cotton mule spinners in England suffer from scr,ctal cancer. On the other hand in the United States during 1926, for example, there were only 33 deaths from cancer of the -5- scrctura, cf which only three cf the victims were textile workers and three were mule spinners; four cf the six were b o m in England and the other two in Canada ^ , which tends tc show that mule spinner cancer is rarely contracted in t<ie United States. In a woolen mill in the United States employing about 200 mule spinners no cases of scrotal cancer were found Since the method of operating this equipment is the same in both countries this striking contrast is attributed by Hamilton ^ to the fact that Scottish shale oil is used in the Lancashire mills. However, the literature is net entirely clear as tc the origin and type cf the oil used in Lancashire in mule spinning 53, Leitch brings out a fact of possible significance, to the effect that cancer is net known in woolen spinning mills, even though the same machines are usod as in the cotton factories, but points out that the re on temperatures in the cotton mills are much higher, possibly resulting in mere relaxation cf the tissues cf the scrotum and permitting entry of oil into the sebaceous follicles. Brockbank however, states that in the woolen iniustry piecing cf broken ends cf yarn is dene with both hands with a forward level binding movement of the body and thus there is net the same friction of the clothes on the scrotum as in the cotton mills. He admits, however, that the same oil is used in both types cf mills. , fts a result cf the preliminary investigation cf Sc.utham and h'ilscn mentioned above, the Manchester Cancer Commissicn, consisting cf mere than fifty members, was organized in 1925 under the 'direction cf Dr. C. C. Twcrt tc investigate the mineral oils used in Manchester cotton mills. Lubricating oils from the various fields throughout the world were found to have widely varying degrees cf activity, A sample of Venezuela oil was very potent while Russian and Pennsylvanian samples were cn an average less than cne-tcnth as active. Purifiei medicinal oil had nc carcinogenic properties and several saponifiable oils, such as sperm, olive, rape, cottonseed -and neatsfoct oil, failed tc produce -6- tumcrs when applied to mice, even under the most severe experimental conditions. In 2eneral terms, the more saturated were the constituent hydrocarbons of the lubricating oil, the less capable were they of inducing cancer in experimental animals, the physical characteristics being the same This preliminary report was criticised severely in an editorial in the "Petroleum Times" of London in that while various oil companies (Anglo-American, Anglo-Persian and Shell-Mex) had contributed LI,OCX) for two years for the support of this investigation, yet the Manchester Cancer Commission had not availed itself of the services and advice of experts from the oil industry relative to the characteristics and methods of treatment of petroleum oils. The Institute of Petroleum Technologists, while making no definite criticisms at this time of the work of the commission, formed a committee of its own to follow closely the work in progress In 1934 Dr. A. E. Dunstan, Dr. F. H. Garner and Mr. James Kewley of the Institute of Petroleum Technologists are shown as members of the Manchester Commission ^1, In 1933, Twort and Lyth of the Manchester Cancer Conraittee reported that by means of solvents, extracts were obtained of high refractivity and correspondingly high carcinogenicity Iheir recommendations for the selection of an oil of low carcinogenicity were as follows: When selecting from several mineral oils with similar gravity, specify that with the lowest refractive index; when selecting from those with similar refractive index, specify that with the highest gravity; when selecting from those with similar refractivity, specify that with the highest viscosity; and when selecting from origin alone, choose in the following order: Russian, Pennsylvanian, Texas, Mid-continent, Mexican, Californian, Persian, Rumania, Borneo, Venezuelan,shale. However, it should be emphasized at this point that these authors state definitely that "adequate refining of any of the oils handled, of no matter what origin, results in a product ........ . possessing only a very low -7- carcinogenicity" 10l+. Also, that a single extraction of an unrefined distillate with SO^ may profoundly lower the activity of a previously very dangerous oil, wnil-j a second extraction may render it almost inert. They state that "it is nrobably commercially feasible to treat oils of any origin, or oils of any degree of carcinogenic activity, so that they may be loss dangerous than even the very best of the straight oils used today". They evidently assume that untreated textile oils are used in the Lancashire mills. Lyth of the Commission further stated 71 that when the refractivity* of an oil was less than 0.5500 it was found to be non-toxic, while when the value was greater than 0,5b00, the oil was highly toxic. Pennsylvanian oils and certain mildly treated oils were an exception. The iodine value of an oil sterns to afford an indication of its toxicity, providing the oil has not been treated and again the higher the value, the more potent the oil. The toxicity increases in the same order as iodine value, except for Pennsylvanian oils which again occupy too high a position. The permanganate values are not regarded as of any value in connection with estimating the toxicity of oils. Lyth adds that extraction with alcohols, acetone, etc., clay and acid treatment, leads to a reduction in the potency, especially in the case of the more potent oils but a corresponding reduction in the refractivity does not always occur. Where a marked reduction in the refractivity does occur, there is, without exception, a marked decrease in carcinogenicity; with a marked increase in refractivity, a corresponding increase in potency. Where the refractivity is not tuch altered, the potency may or may not be affected and further tests are necessary. In spite of the apparent definite findings and recommendations of the Manchester Cancer Commission, the Cancer Research Committee of the Institute of Petroifeum Technologists 51 Was not convinced that "uhe so-called incidence cf * (Refractivity Refractive Index - 1 DZNSITY API 04624 -8- cancer is in any shape or form connected with the use of spindle oils". No elaboration of this statement was given, but was possibly based on refined oils cnly being used as textile lubricants. An editorial in the "Petroleum Times" of London in 1937 once again attached the conclusions of the Manchester Committee, pointing out that only one oil from each of a number of countries was examined , In 1937 the Federation of Master Cotton Spinners Association sent out a letter to its members recommending that when purchasing spindle oils a guarantee should be obtained that the oil conforms to the specifications of the Manchester Cancer Commission, and that tests had shown that many of the oils in use at that time conformed to the specification. V/hile throughout the reported work of the Manchester Cancer Commission it is stated repeatedly that acid or solvent treatment of a potent oil greatly reduces or eliminates its activity ^7, 102, 104, 71} yet n 1939 Twort and Lyth investigated acid and clay treated distillates from a Borneo oil and found them to be active, the maximum potency being at a viscosity of 200-250 cp at 25cC. Molecular distillation gave a greater concentration of the carcinogenic material than was obtained by ordinary distillation at from 3 - 1 0 mm. In confirmation of previous findings the middle fractions of this Borneo oil were mostly responsible for pathological changes in the organs, A carcinogenic shale oil was separated by molecular distillation into fractions which were subjected to chromatographic adsorption. Two apparently pure hydrocarbons have been isolated and are being investigated 2,109, A recent report (1941) by C. C. Twort of the Manchester Cancer Coanisaion 1^9 states that animal tests are variable, lengthy and costly and that a "ore reliable estimate of the carcinogenicity of oils can be obtained from the refractive index and viscosity. (Yet the data on which selection of these two Properties was based were obtained by means of this variable skin test.) Woodhouse of the Birmingham Cancer Research Laboratory also states that mouse tests to determine carcinogenicity are difficult to correlate with human tendencies to cancer unless these animal tests are strongly positive or negative 121, For example, two oils were tested (a) from a spinning mill where no cases of mule spinners cancer had been recorded, and (b) from a mill where six cancers had recently been reported. Mouse tests indicated slight carcinogenic properties in the case of the two oils but a greater action on mice of (a) than (b). Dr, E. M. Brockbank, chairman of the Manchester Cancer Commission, has briefly summarized the investigations of the Commission in a recent publication 16, He lists the hygienic precautions to be exorcised in mule spinning and urges the adoption of the oil specification given previously by Twort. He also makes this interesting generalization: "As a general rule an oil that is strongly dermatitic will not be strongly carcinogenic and vice versa". This is also mentioned by Kennaway ^1 who states that cyclohaxene (which is non-carcinogenic) is extremely irritating to the skin and should produce cancer if chronic irritation were an essential factor in carcinogenesis. As mentioned previously, shale oils are very carcinogenic and in the Scottish shale industry the case incidence of skin cancer is about 0.1$ per annum among the oil workers but 0.5$ among the paraffin workers 53 (this is based on a 28 year record). This activity of paraffin is restricted by Schwarz and Tulipan to the crude product, the refined wax being inactive, which view is supported by Wood who states that the active components are present only in the crude paraffin oils. With regard to the refining of petroleum oils. Wood 120 made an investigation of refineries in Pennsylvania and found no scrotal cancer, which was confirmed by Heller However, Heller found evidence of carcinogenic compounds in Mid-Continent oils as refined in plants in Ohio and Indiana. Here il boils are fairly common and in some cases lead to skin cancer. In one case - 10- a paraffin pres s ma n i n the M id dl e YJest w a s treated f o r "wa x boils" f o r three years when a cancerous growth developed on the right forearm and was removed, but eight years later a second similar growth in the same place had to be removed. Heller also found records of cases of skin cancer in another refinery, using crude frcm the Lima field; eight cases had occurred in this refinery and one was fatal. All of these cancers were preceded by warts. The length of exposure before malignancy appeared varied from four to thirty four years. The part most often affected was the scrotum and all but one man worked in the paraffin department. These cases were caused by unrefined oils and Hamilton 40 states that so far there is no proof of the occurrence of skin cancer in the U.S. from the use of refined lubricating and spindle oils which have been acid-treated, Heller & believes that the relative freedom from occupational cancer in the U.S. is due to the mechanization of industrial processes, preventing direct contact with the pitch and tar; the extensive employment of negroes, who are apparently less subject to skin irritants than whites; the use of refined lubricants from crudes which are poor in carcinogenic properties, and the use of tar from coke-ovens instead of from gas works, Phillips ?? reports the particulars of a study carried out by the U.S. Public Health Service as to the incidence of occupational cancer in Texas, The records of ,1190 individuals having microscopically verified akin cancers were analyzed, covering the period 1920 to 1940, The occupation cf the largest group of these patients was outdoor work (farming and ranching); the work of housewives comes next in order, followed by various activities requiring moderate outdoor life. The professions were neoct, followed by laborers and carpenters. The / railroad and petroleum industries furnished few cutaneous cancers. Safafer and Sitgreaves in a U.S. Public Health report issued in 1940 ^ analyze 70 cases of cancer recorded for the male members of the sick benefit plan refining company during the period 1933-38; there were 46 deaths. The death rate was 0.78 per 1000 and a frequency of 1.2 per 1000 (all U.S. death rate 0.96 per 1000), Almost 10% of the deaths were related to the digestive system and the rate for this site was higher than in the total population. Deaths from cancer of the genito-urinary system was b.5% of the total, compared to 15.0% in the case of the total population. In 1934 Campbell-2 21 ^ d e laboratory tests on mice with dust obtained from tarred roads. This dust caused warts and cancer of the skin and in six months 24 out of 59 mice showed typical tar warts, half of which developed malignancy. This finding was confirmed by Kling, Samsonow and Heros, ^4, ^5 who also separated a substance containing the benzopyrene nucleus from the tar. However, Hogouneg ^ is doubtful of the danger from read tar since it usually takes years of direct contact of coal tar to the skin to produce skin cancer. (Teutschlaender 91 calls attention to the fact that almost all industrial cancers require an exposure of about ten years before growth appears, although a few cases may arise much later.) Valade m likewise is of the opinion that while primary lung tumors can be induced in mice painted with tar or exposed to inhalation of dust from tar roads, yet these results cannot be transferred to humans. Animals other than mice should be employed in experiments and an inquiry should be carried out on workers exposed daily to such dusts. While the manufacture of briquettes in England is attended by a high cancer rate, 58 since high-temperature tar is used, yet in the few plants in the U.S. making briquettes capcer is entirely absent, partly due to the lack of contact with the binder since the process here is entirely mechanized and partly due to the use of petroleum asphalt as a binder, ^ . This finding was confirmed by Wood -*-20 in His investigation of briquette manufacture in Pennsylvania. The addition of glycerides 9 reduces the carcinogenic potency of mineral oils but net to as great an extent as lanolin. Speakman and Chamberlain state that while alcohols have not been used for this purpose there can be little doubt that such polar compounds will reduce the risk of cancer formation by promoting emulsification, since an oil which is easily and completely removed from the skin 12- must carry less risk than one which is difficult tc emulsify. These investigators Lsc believe that polar compounds in a mixture with mineral oil may, however, function in yet another way. It is known that the carcinogenic agents of mineral oil when associated with unsaturated compounds are free to concentrate at any surface tc which the cil is applied, the non-pclar paraffin molecules offering little or nc resistance. However, when oil-soluble polar compounds, such as cleyl alcohol or wool-fat ether, are mixed with mineral oil they concentrate at the surface, excluding the less polar carcinogenic hydrocarbons. Sequeira stresses the necessity of absolute cleanliness of body and clothing, the application of castor oil to exposed surfaces and medical inspection every three months. Brcckbank ^*5 suggests a mixture of lanclin and olive cil be applied to the skin. Duckham advocates the use of an oil-solvent cleanser similar tc the ether soap used in hcspitals in order to remove all cf the lubricant from the peres 3 . In view cf the suggested use cf lanclin the following should be of i . particular interests Dr, EJ. V. Ccwdry, cf the '.Vashingtcn University School cf Medicine, St, Louis, has just announced (N.Y. Herald Tribune April 29, 1945) that cells can be sensitized to become cancer cells by treating them with a substance which dees not cause cancer and which will even prevent powerful cancer-producing chemicals from exhibiting that property. . . Fcr example, when the powerful carcinogen methylcholanthrene is mixed with lanclin it is without action when applied tc the skin cf mice, although alone it always results in cancer. However, when these mice were then treated with methylcholanthrene in benzene they developed cancers more quickly and tumors cf greater virility than mice which had not received the cancer-preventing treatment. MPD-VL . DYS - 13- R2TE33NC3S 1 . Anon., Cancer from Spindle Oil, Oil and Color Trades J., July 2, 1937. 38 A letter sent out by the General Committee of the Federation of Master Cotton Spinners1 Association recommends that when purchasing spindle oil members should obtain a guarantee that the oil conforms to a specification of the Manchester Cancer Committee which recently issued a fofaila claimed to minimize the so-called cancer-producing elements of mineral o i l . Tests showed that many of the oils in use at present con form to this specification and are obtained at regular prices. 2-, Anon., Cancer and Mineral 011b, Oil and Color Trades J., 102, 695 (19^2) The report of the Manchester Committee on Cancer, issued for the year ended October, 19^1, states that in efforts to isolate and char acterize individual carcinogenic hydrocarbons from shale oil, recently appreciable quantities of crystalline material have been obtained, but it is too early to diBCuse results in detail. As far as can be judged, all fractions obtained from Venezueltui Oil by chromatographic adsorption are active. Proprietary colioidB have varying effects, depending on the oonditions of the experiment. A colloid containing a chlor-conpound was found less efficacious than an olive oil-lanoline mixture as protection against the carcinogenic action of shale oil, while the reverse appeared to be the case when the carcinogenic agent used was benzpyrene, 3. Anon,, The Problem of Cancer. Petroleum Times, 2^, 59 (193^) (a) The following appeared in a recent issue of the British Medical Journal in connection with the use of mineral lubricating oilB in the Lancashire cotton mills: "The Manchester Cancer Committee, while studying the part played in the production of malignant growthB by the lubricating oils used in cotton mills, has obtained information about the earcinogenetic power of various oIIb and the concentration within then of a cancer-producing principle. In the course of this research, two pure compounds of known chemical composition have been proved capa ble of producing tumors, h a study has been made of the factors which change a non-carcinogenic into an active carcinogenic substance. Al ready some of the methods for destroying the cancer-producing power of certain oils have proved to be effective, at least in part, and one method lei to the preparation of a purified oil which, when subjected to vigorous test, has failed altogether to produce cancerous growths. Representatives of the cotton industry, after comparing this oil with . the crule untreated oil have said that its lubricating power is unim paired, and the Manchester Committee is therefore able to hold out the hope that before long it may be possible to put on the market on oil ( which fulfills the needs of industry without being a source of danger'to the workers." Assuming that the use of spindle oils be such a source of danger, it almost necessarily follows that other lubricating oils which come into closer physical contact with the worker must be sourceB of higher potential danger than any of the light lubricating oils used in the . looms of the Lancashire cotton industry. It night be proved upon in vestigation that little difficulties would present theneelves in the production of a spindle oil which is noa-earcinogenie, and lest the present attack widens itself to include the whole range of mineral lubricating oils, it would be advisable to make an investigation of the most embracing character. - 14- Anon., A Dangerous Report on Lubricants ani Cancer, Pet. Times, 27, 31^-320 ' (1932) Criticizes the report of the Manchester Cancer Committee in that the Committee has accepted contributions of l000 for two years from the Anglo-American, the Anglo-Persian and the Shell Mex but has not availed itself of the services and advice of experts from the oil industry- relative to the character and methods of treatment of petroleum oils. c Anon., Manchester Committee on Cancer Report. Pet. Times, 8, 295 (1937) ' The 1935-36 report of the Manchester Committee on Canc.pr claims that "with a knowledge of the refractive index of an oil, ani of the viscosity, one can form a more reliable estimate of its cancer-producing powers than.by the application of the sample tc> the skin." It is pointed out, however, that similar conclusion in the 1933-3^ report was based on insufficient evidence and that some discrepancies with animal tests were admitted, and that in the 193^-1935 report the animal tests were reverted to. It is also pointed out that the above conclusion was based on the examination of anly one oil from each of a number of countries. 6, Occupational Cancer of the Skin. Annual Report, Chief Inspector of Tactories and Workshops, Year 1937 - a table showing distribution of epithelionatous ulceration by industry for each of the years 1933-1937 is given in an abstract in American Journal of Cancer, U, 610 (Dec. 1932) Tar distilling ani cotton mule spinning.take the greatest toll. The increased 1937 figures for tar distilling cases is attributable to voluntary periodical examin ation in some plants. 7. Alapy, 3. Cancer Prophylaxis by Preliminary Treatment with Carcinogenic Polycyclio Hydrocarbons. Z. Krebsforsch. Ug, 3209 (1938) Mice and rats were treated with very small doses of 3 carcinoeenic hydrocarbons (beaso-pyrene, metlylcholaathrene and 1, 2, 5 . 6-dibenzan thracene as a method of protection against the implantation later of highly virulent tumors. Usually a single subcutaneous injection was made of the carcinogenic agent dissolved in sesame oil. The most effi cient dose in mice was 1.5-3y ani the most favorable time UCV.70 days, before the implantation of the tumor emulsion. Dibenzanthracene was . somewhat the most effective. The protection in mice was only slight. Development of the tumor was delayed 5-6 lays and for 5-6 days was slow. Growth then beoame rapid, and on the 17th or 18th day after implantation of the tumor the tumors were of the same size ir. the animals with treat ment and the control animals . Ho hindrance to tumor growth was obtained in rats given l-100y doses, occasionally 150-180y doses 3-^-SO lays before implantation of the tumor. A definite active protection cannot be obtained by this method. , 8 Bachaana, W. 35. et al. Production of Cancer by Pure Hydrocarbons. Proc. Roy. Sc. 3122, 3U3-6S (1937) With respect to high carcinogenic potency, nethylehclanthrene is not surpassed by any compound yet tested, although it is almost equaled by cholanthrene. Production of carcinoma is favored by introduction of substituents into the 5 position of the 1 , 2-benzanthracene mol.; A P I 04631 15- 2-We~3 , U-benzophenanthrene 1b carcinogenic to & high degree eb are certain hexacyclic hydrocarbons derived from the pentacyclic hydrocarbon 3 , U-benzopyrene. _ 9. Badger, G. M. et al. Production of Cancer by Pure Hydrocarbons. Proc. Roy. soc. B 122, U39-67 (19^0) Information as to the most effectual method for the production of any particular tianor (painting, subcutaneous injection, feeding) is not decisive; in the two latter the fur is always contaminated, and inhala tion and swallowing cannot be excluded by any of the methods. The 3, U-benzophenanthrene compounds possess carcinogenic properties, and apparently are more active than the benzanthracenes in the production of multiple tumors, cholangioma, and tumors of the lung; the 1 , 2-sub- etltuted compounds are more active with respect to gastric tumors. Compounds substituted on the 1, 2-side are usually more carcinogenic than those substituted on the 6 , 7, 8-side. Among the 1, 2-benzanthracenes, the 5-n-Bu, 5"n*^ni cad 5-n-hexyl resemble the 3 U-benzophenanthrenee in their association with a higher incidence of lung adenomas and nulti- pie tumors, and a deficiency in sarcoma production, . . 10. Badger, G, M. et al. Production of Cancer by Pure Hydrocarbons. Proc. Roy. Soc. B131. 170-82 (19^2) In the series of S-alkyl derivatives of 1, 2-benzanthracene (lie, St, Pr, iso-Pr, Bu, C eH j j , C g B y , C7H 1 5 ) members showed progres sive diminution or carcinogenic power on the shin; member with more than 3 C atoms in the side chain did not produce sarcoma. Yith derivatives of 3 , U-benzophenanthrene, substitution in position 2 .and, to a lesser extent, In position 1 , promoted carcinogenic action; most of' these com pounds were deficient in power to produce sarcoma. 1. 2. 3 U-Tetrar- methylphenanthrene had a slight but distinct ability to produce skin . tumors, 3 , U, 5 6-Dibenzofluorene had no action on the skin and there by differed from the 1 , 2 , 3 , U-, 1 , 2 , 5 , 6-, and ,1 ,2 , 7 , 8-conpounds. 1 * 2 , 5 , 6-Dlbensoearbazole exhibited a slight tendency to produce tumors of the liver. While multiple tumors could not be ascribed with certainty to the action of the administered compounds, the most striking cases of multiplicity occurred under the Influence of 2 , 3 U-substituted pheaanthrenes, 1, 2, 5 , 6-dibeniocarbazole and 1, 2-5, 6-dibenzacridine.. 11. Barry, G. et al. Production of Cancer by Pure Hydrocarbons. Proc. Roy. Soc. 117. 318-51 (1935) , A large number of compounds, -chiefly tetracyclic and pentacyclic aromatic hydrocarbons, were teetel for cancer-producing action, with alee as experimental animals . Considerable cancer-producing power was possessed by 1 , 2-bensopyrene (from coal-tar pitoh). methylcholanthrene (a darlr. of deoxycholic acid of bile) and 3. U-benzophenanthrene. In order to be carelnogenio, derive, of 1 , 2-benzanthracene must contain . substituents in positions 5 anl 6 . . 12. Bergaann, 7. Mechanism of Tumor Production by Chemical Agents. Cancer Research, 2, 660. (I9U2 ) The following principles for tumor production by chemical agents are hypothetically established; 1. The form and size of a carcinogenic hydrocarbon and of its related heterocyclic compound determine its activity. Every substance which imitates more or lees closely a given parent structure resembles it also in its blastomatogenic action. - 16- 2. In the living cell, the carcinogens are adsorbed, by an acceptor possessing a definite adsorption area. This sets an upper limit for the dimensions of the active compounds. A lower limit is given by a decrease in adsorhahility with decreasing size of the molecule. All carcino gens are conceived as parts of an "ideal carcinogenic structure," h. A carcinogen can he inactivated hy additions which prevent its proper adsorption. The mechanism of this hindering effect is discussed, 13, Bonser, G. M. Tumors of the Skin Products hy Blast-Furnace Tar, Lancet 1, 775-6 (1932) " The results obtained with four samples were remarkably similar to Berenhluu's and blast furnace tar is therefore carcinogenic, though not so potent as the gas tax employed. The reason tbat.it has been innocu ous for man is that the yield Is small, and it is regarded as a waste product and is disposed of without further handling, . lU, Boyland, E. and Brues, A. U. Carcinogenic Action of Dibenzcarbazolee, Proc. Hoy. Snc. 122B, U29-U1 (1937) Cancer of the bladder is unduly frequent among chemical workers, and those dealing with naphthylamines and benzidine seem most liable to the disease. It has hot been demonstrated satisfactorily that naphthyl amines are carcinogenic, and it is possible that it is not they which are responsible for cancer of the bladder, but impurities formed during their manufacture, such as dinaphthylamines and dibenzcarbazoles. Sub stances of this nature were therefore tested for carcinogenic activity by painting on the skin of mice and one (which proved most active on mouse skin) also by subcutaneous injection into rats. . The most active was 3:^:5:^ * i ^ enzeAr^,'3'z0^e but this was toxic. It produced malignant skin tumors in mice in ISO days. Of the other sub stances tested, l:2 s5 :6-dibenzcarbazole was carcinogenic and 1 :2 :7 : 8-dinbenzcarbasole feebly so. The dinaphthylamines, 0-aninoazotoluene, known to produce hepatoma, and diamino-azobenzene (chrysoidine) all failed to produce tumors on the skin of mice. Spindle-cell sarcomata, one of which was proved transplantable, were produced in rats by sub- curaneous injections of a colloidal suspension of 3 s^:5 !6-dibencarbs- . sole. . . . 19, Brockbank, E.U. Mule-Spinner's Cancer. Brit. Med. J . , 622-3 (h.26Ul) 16. Brockbank, Z. M, Hale Spinners Cancer. Epithelioma of the Skin in Cotton Spinners. H. K, Lewis and Co., Ltd., London. 36 pp* (19^1) The first known case of scrotal cancer in a mule spinner was re ported in Manchester in 1887, 37 years after the introduction of mineral lubricating oil; before that time sperm oil and neatsfoot oil had been the principal lubricants. It is now known that cancer of the skin, whether of the.scrotum or elsewhere, in mule spinners is caused by carcinogenic oompounde which are present in mineral lubricating oils though not in lubricants derived from animal or vegetable sources. Some mineral oils are more carcinogenic than others, that derived from shale being particularly dangerous, and it has been leasned by experience .that cancer is more likely to be caused if the same lubricant is used con tinuously, than if the kind of oil employed is occasionally changed. It has been found also that by mixing animal or vegetable oil with -17 17. Burrows, H , , Hisger, I., and Kennaway, E. L. Experiments in Carcinogenesis: the Effect of the Subcutaneous and Intraperitoneal Injection of Lard, Olive Oil and Other Patty Material in Bats and Mice, J, Path. Bact, . 1+19-26 (1936) 18. Campbell, J. A. Experimental Production of Cancer by Duet Obtained from Tarred Hoads. Brit. Med. J. , 2.3.3U, 233-I+ This dust caused warts and cancer of the skin of mice with metastases sometimes in the lungs; in 6 months 2U out of 99 mice showed . typical tar warts, half of which developed malignancy, 19. Campbell, J. A, The Effects of Hoad Dust "Freed" from Tar Products Upon the Incidence of Primary Lung Tumors of Mice. Brit. J, Exptl. Path. 18, 215- 2U (1937). . It has been shown that dust from tarred roads causes cancer of the skin of mice, Hoad dust minus tar, as removed by benzene, doeB not cause cancer of the skin of mice; it stimulates the production of lung tumors in mice, but not to so great extent as when the tar is also present. . 20. Campbell, J. A, Carcinogenic Agents Present in the Atmosphere and Incidence of Primary Tumors in Mice. Brit. J. Exp, Path,, 20, 122-32 (April, 1939) The author has continued his research on substances that might induce lung tumops. He employed chimney soot and soot scraped from exhauBt pipes of engines burning heavy oils. Rate were exposed to these dusts for 10 min* an hour for 6 hrs,, 5 days a week for 1 yr. The death rate o f both groups was well within the limits of that for the controls but the number of lung tumors was somewhat higher. Of those exposed to exhaust pipe soot, 33$ living 10 mos. or more developed tumors. The . most active substances tested was dust from tarred roads. Data are also given on mice whose skin was painted with "tar" from these substances, 21. Clark, H, Y. Cancer from Lubricating Oils. Oil-Color Trades J., 11.93^. 1278-9 . . 22. Cook, J. ,, Hewett, C, and Hieger, I, C o a W T a r Constituents and Cancer. Mature, r$0 , 926 (1932) Several hydrocarbons were isolated from coal tar which were active .in producing cancers and which had the typical fluorescence spectrum of oaroinogenio fractions. She most active hydrocarbon isolated was 1, 2- beasopyrene which produced cancer in half the tine required by 1 , 2 , 5 , 6-dlbensanthracene. Perylene and U, 5-benzopyrene were also isolated, 23. Cook, J, M. et al. Production of Cancer by Pure Hydrocarbons. (a) Proc. Boy. Soc. (London), Bill, U55- & (1932); (b) Proc, Hoy. Soc. (London),Bill, US5-96 (1932) (a) Mice we re. used as exptl1, animals, and a study was made of the action of 22 different polycyclic aromatic hydrocarbons, contg. }~8 rings in their resp. moIs. and applied in soln, to the interscapular region, usually twice weekly. Of these pure compis. only 1, 2, 5 , 6-dibenzan thracene and certain closely related compds, produced cancer; it was active la 9 lifferent solvents, and was effective when applied in 3.003$ soln. in CgE'$, Of 273 mice treated with this eonpd., 107 developed tumors, including 77 epitheliomas and 21 papillomas. API 04634 1 - 18- (b) The Investigation has been extended to include 52 aidnl. poly cyclic aromatic conpds . Tumors were produced by 6-isopropyl-l, 2- benzanthracene, 5i 6-cyclopenteno-l,2-benzanthracene, phenanthroacenaph- thene, and 5 derivs. of 1,2,5,6-iibenzanthracenej 2 *-4ae, 3'-uIe, 9-31*2 9-tieO, 9,10 (C6H^K2)2 . ' gU. 25. I 26. Cook, J. 17,, Hewett, C. 1, and Kieger, I. The Isolation of Cancer-Producing Hydrocarbons from Coal Tar. J, Chen, Soc., 395-^05 (1933) The preparations derived from coal tar pitch by a variety of solvent extraction nethois, the fractions separated by formation of picrates, distillation and crystallization, and the hydrocarbons, 1:2-benzpyrene, and Uj5-benzpyrene, perylene and 1,2-benzanthracene, have proved carcino genic and have given the sane fluorescence spectrum (bands at H.000, ^180 and UUoQA0). The original coal tar pitch contained not less than 0.0039^ of 1, 2-benzpyrene. . Cook, J. W. Synthesis and Biological Effects of Carcinogenic Hydrocarbons. Chen, and Ini., 1022-3 (193 5) Certain forms of skin cancer due to occupation causes in industries where shale oil, coal tar and lubricating oil a r e .employed, have been shown to be due to the benzanthracene group of hydrocarbons which also impart fluorescence to the oils. The exact nature of cancer formation in the human body has not been explained although a sinilar benzanthra cene hydrocarbon has been found to be produced by body changes from substances normally present in the human body. . Cook, J . Carcinogenic Hydrocarbons and Their Relationship to the S te ro ls. Cheni. Weekblad, 32, (1935) Review of historical development of recognition of the cancer- producing constituents of coal tar and earlier investigations; the development of fluorescence spectroscopy and the systematic study of ' synthetic carcinogenic hydrocarbons including a sunnary of the results obtained from the examination of a complete series of tetra- and penta- cyclic hydrocarbons and a moderately wide range of benzanthracene derivatives. The speculation is advanced that a mesc H atom in a completely aromatio structure plays some role in the carcinogenic process. The isolation of 1,2-bensopyrene from coal tar and its synthe sis are recounted and. an account is given of the cyclization of bile acid derivatives, and tbs eventual synthesis of methylcholanthrene, a carcino genic hydrocarbon related to the sterols. It is inferred that there is some ensymic factor present in the animal body which is capable of effecting dehydrogenation of the sterol ring system and that excessive activity of this factor may conceivably contribute to the production in vivo of carcinogenic compounds. . . 27. Cook, J. V., at al. Chemical compounds as Carcinogenic Agents. An. J. Cancer, 2^, 219-59 (1937) ' A full survey is given of the carcinogenic chemicals, dealing both with their chenical relationships and their biologic effects, bringing together, under well chosen headings, all the material published up to the end of 1936 They include not only the hydrocarbons of the benzan thracene type, but also the azo compounds, estrin, the styryl quinoline derivative discovered by Browning et al., and the inorganic compounds zinc chloride and arBenie. A bibliography of 19U references is appended. - 19- 23, Cook, J, W. and Kennaway, E, L. Chemical Compounds as Carcinogenic Agents, First Supplementary Reoort: Literature of 1937* Am. J. Cancer, 33, 50-97 (1938) ` Authors present an exhaustive review of this subject which should be of Interest to all industrial physicians. It continues the earlier review and the two reports together have bibliographies totaling 37^ references. 29. Davis, E, Chemical Carcinogenesis, Drugs, Dyes, Remedies and Cosmetics with Particular Reference to Bladder Tumors. J. Urol. Ug, lU (19^3) Author discusses at considerable length the large number and variety of proved chemical carcinogenic agents which may be introduced into the body by ingestion, inhalation, injection or cutaneous application. He strongly inclines to the theory of some chemical carcinogenic agent. Uany are cited such as derivatives of coal tar, crude mineral oils, an anilin dye "intermediate", azo dyes and estrogenic substances. The aniline bladder tumor of dye factory works develops after years of ex posure to what are probably extremely small daily doses. The theory is advanced that there may be many other carcinogenic agents as yet unknown which are unknowingly encountered in the routine of daily life, and perhaps through the use of many drugs, patent medi cines and eosmetics, vitamins, sex hormones, and the tremendous list of anilin dyes used in the coloring of food stuffs,and fabrics. 30. Downing, J. G. Industrial Dermatoses. J. Ind. Hyg., 1J, 138-I65 (1935) A review with 208 references. A section on cEemical agents includ ing inorganic compounds, hydrocarbons and crude coal tar products and other organic compounds; treatment and legal,aspects. 31. Fell,'A. Oil Button (Elaiokonioeis) PreeseMed., ^0, 15^1-2 (1932) Description of a dermatitis in industrial workers caused by heavy , mineral oils, ineluding treatment and prophylaxis. 32. Fieser, L. F. Carcinogenic Activity, Structure, and Chemical Reactivity of Polynuclear Axvoatlc Hydrocarbons. Am. J. Cancer, U, 37-12^ (1938) A long review which Includes; I. a.critical evaluation and compari son of the methods for determining carcinogenic activity; II, informa tion concerning the preparation and purification and the commercial sources of the carcinogenic hydrocarbons; III, a summary of the work on correlation of chemical structure and carcinogenic activity, and IV, a omaary of investigations on the metabolic fate of various active hydro carbons. There is a very extensive bibliography. . . 33 Fieser, L. T. Production of Cancer by Polynuclear Hydrocarbons. Univ. Penna. Bicentennial Coaf* Cause and Growth of Cancer, 1-27 (19^1) . A review devoted to H-containing carcinogens, relation of carcino genic hydrocarbons to the steroids, carcinogenic activity, chem. struc ture and chem, reactivity, nature of a possible reaction leading to carcinogenesis and of the metabolism reaction. If carcinogenic hydro carbons can be produced at times in the body by steroid metabolism, their me-et likely precursors are among the steroids of the adrenal cortex. The Initiating action of a hydrocarbon in earclnogenesis probably Involve substitution in the hydrocarbon at its most reaotive center, probably a direct interaction of the hydrocarbon with an S-S linkage of the cell 20- protoplasm. Metabolic elimination of a carcinogen probably is a detoxi cation produced by a mechanism different from that leading to carcipo- genesis, and involving a different point of attack in the mol. The reaction of detoxication and that of carcinogenesis are competitive. Detoxication may involve biol. hydroxylation to a phenolic deriv., or conversion into derivs, of mercapturic acid. , tU, Fieser, L. F. and Fieser, M. Carcinogenic Hydrocarbons. "Organic Chemistry", 19HU, SlU-26. Carcinogenic activity and structure; correlation with chemical reactivity; methods of synthesizing carcinogenic hydrocarbons. . 55, Firquet, J, and Maiter, M. A. Pitch Cancer aB an Occupational Disease. Archive de Medecine S o d a l e et d'Hygiene et Revue de Fathologie et de Physiologie du Travail, I I , 797-807 (1939-^0) . The authors report their experiences made in medical supervision of 126 workers in the province of Liege, working with pitch or tar.. There were found two epith^liomata only, and no lung cancers, V. Henry made a chemical examination of various pitches as to their content in 1.2 ben- zeneanthracene.and 3*^ benzopyrene, (the two moBt effective cancerogenic substances in animals) and he found in the pitch 1-9# of the first, traces up to O.U# in.the second. The examination of the pitch dust in the two briquette factories revealed mostly large particles: in the work shop 80# of a diameter of 50- 100u, in the storage rooms 90# of 20- 50u. Therefore it seems-- accordlng to the authors*-- that substances which are cancerogenio to animals are not for men, but more research is neces sary. (The material is much too slight for any conclusions in the opinion of the abstractor.). ' 37. Gafafer, W. M. and Sltgreaves, R. Disabling Morbidity and Mortality from Cancer among Male Employees of Oil Refining Company, with Reference to Age, Site and Duration, 1933-38,inclusive, U.S. Pub. Health ReptB. 1517-1526 8.23.UO) . . . 38. Gugllenlnetti, M. Do Macadam Roads Produce Cancer* Hull. Acad. Med., 122, 89-9U (1939) The author first reviews the literature. He questioned varinuB hospitals in some of Germany's large cities regarding the number of observed cases of cancer and sent, these reports to the managers of the road building system in these cities. Increase of cancer was affirmed . but without relation to macadam roads. 39. Hamilton, Alice. Cancer from Tar and Petroleum, "Industrial Poisons of U.S.", . Ulo-7 (1925) ' fco. Hamilton, Alice. "Industrial Toxicology", 13^, 253-^ . Occupational cancer is rare in France. In. the LT.S. the only pub lished case up to 1930 was the case of a man who had worked for 20 yrs. at the paraffin process in a petroleum refinery. In 1928 the Health Committee of the League of Nations requested its members to aid in a world-wide inquiry into the occurrence of occupa tional cancer by undertaking a study of the question in their own countries. The Rockefeller Foundation then made it possible for Imre API 04637 '21- H e lle r to make an Intensive in vestiga tio n in th is country, and hie report was published in 193 H e lle r confirmed the impression held by American a u th o rities on cancer, that those o f occupational o rigin are very very rare in the United S ta te s , He found in the records o f the two New York h o sp ita ls sp e cia lisin g in cancer only 37 cases of skin cancer that could p o ssib ly be traced to tar and tar products, 26 o f these occurring among men handling gas-house tar or p itc h , only two in coke-oven tar or p itch workers. In a Cleveland plant making carbon aad dry b a tte r ie s , imported E n glish gas-house p itch was used up to 1906, when i t was supplanted by American coke-oven p it c h . There were 21 oases of cancer among the work ers in th is p la n t, only h o f which were in men handling coke-oven p itc h , and these were not considered by the physician in charge to be indubitable cases. U l, H artw ell, J, L. Survey o f Compounds which have been Tested fo r Carcinogenic A c t i v i t y . U, S , P ublic Health S e rv ice , 371 pp. (19^1) This b u lle tin represents a survey of the fie ld of chemical carcino genesis in the higher animals: the action o f carcinogens on isolated tis s u e s , tissue cu ltu re s, p la n ts , protosoa, and b acteria is not consid-. ered. The lite ra tu re is covered to 1939, and the compilation also includes experiments with 153 compounds from the unpublished work o f Dr. M. J , Shear and Dr, H, L. Stewart o f the N ational Cancer In s titu te , The re su lts o f the testin g o f 6l o f these compounds are newly reported, while U5 are new to the whole cancer lite r a tu r e . Altogether the work comprises data referrin g to 696 chemical substances: o f these, 169 are reported to be carcinogenic, apart from 23 observed as causing paiilomas on ly. A fte r an introductory d iscu ssio n , the b u lle tin takes the form o f a tabular review on the follow ing c la s s ific a tio n (figures in parentheses show the number o f entries fo r each category): A. Inorganic substances (35) B, Organic compounds: I , A lip h a tic (36) ; I I , P o ly c y c lic [ iic y c lic (26) , t r ic y c lio (37), te tr a c y c lic (152) , pentacyclic (llU ), hexacycllc and cyc n, higher (25)J lic (59): ? U Ill, nclas Aso-compounds sified (77). (39): IV . Steroids (S6); V. Hetero Vlthin this arrangement, compounds are individually numbered and then grouped according to prototypes and alphabetically. The tables give structural formulae, literature references, particulars of species, strain, sez, aad number of animals used, preparation, dosage, and rout? of administration of oompounds, nature of sites of tumors induced, with details of duration of experiment and survival rates and other remarks. The above conditions shew the wide range of information necessary in order to assess the carcinogenic activity of a given compound. The author draws attention to the incompleteness of the data for many of the com pounds listed, aad urges the more systematic investigation of compounds already studied in a preliminary fashion, and for the filling of large gaps among substances which it would seem desirable to test. The review is completed by a bibliography (over 1200 references) and separate indexes to compounds, routes of application, vehicles, animal species, and tunor- sites. . . to. Heller. I. occupational Cancers (in U.S.). J. Ind. Hyg., 12, 169-197 (193) The chemical properties o f gas-works, coke-oven, producer-furnace and blast-furnace tar9 and pitch are briefly outlined with a view to correlating these properties to cancer incidence among workmen in the industries involved. As a result of extensive surveys and health record API 04638 23- examns., gas-works tar and pitch were responsible for 70 .2# of the cases while coke-oven tar and pitch were held responsible for only 5 ,b#, Coke oven tar is much the less injurious especially when cognizance is taken of the fact that coke-oven tar is used much more extensively. The presence of olefins in gaB-works tar seemB to he of particular importance and may he a cause of oil cancer. Occupational cancer does not occur in the briquet mfg. industry . Mineral oils vary in carcinogenic activity according to their olefin or uneatd. hydrocarbon content. There is no method for.the detn. of the amt. of olefins in the various erode oils; if such a method existed, it would be possible to measure the cancer- producing power of mineral o IIb , Cancer is not attributable to the occu- pagion of mule spinner in the U.S., possibly because of the carefully refined lubricating oils used on the machines, thus ensuring relative freedom from olefins or unsatd. hydrocarbons. . . Henry, S. A. Study of Tatal Cases of Cancer of the Scrotum. J. Am. Med. Assn., 102, 1667 (1937) Hieger, I , , Spectra of Cancer-producing Tars and Oils and of Related Sub stances. Bioehem, J . , 2U, 5 0 5 - H (1930) , U5. Hoffman, F. L. Mule Spinners Cancer. Monthly labor Rev. of U.S., 7, U57- U75 (1928) . 1*6. Hoffman, W. J. Industrial Cancer. Prevent, Med., 6, 7-3^ (193&) One of the seven types of industrial cancer discussed is cancer of skin in workers exposed to coal, tar, pitch, soot, shale, petroleum and arsenic. They may cause aa epitheliomatous form of cancer. Hogouneng, L. The Cancerigenic Hydrocarbons from Tar and the Tarring of Roads, Ann. Hyg# Publ. Sociala, 2J, 1-7 (1939) The cancerigenic hydrocarbons found in coal tar produce skin cancer in exposed worker usually only after direct contact with the skin for long periods of tins It is believed that man is much more resistant to the action of thece materials than lab, animals. ... Hueper, W. C. Cancer in Relation to Occupation and Environment. Bull. Am. Soc. Control Cancer. 25, Vo, 6 (June, 19^3) Owing to industrial development, the general population and factory workers in particular, are exposed t o m a r y new environmental factors, many of which are disease producing. Occupational cancers are caused by numerous chemical and physical agents. Among them are the heavy metals, nitrates, aromatic y n < c o m p o u n d s , benzol, asbestos, mineral oil, soot, ` radio-active substances, ultraviolet radiation and X-rays. The author cites statistics taken mainly from the records of industrial concerns, but points out their shortcomings. Cancer of the urinary tract due to coal-tar is the most recent addi tion to the list of occupational cancers. It is most frequent in the aniline iye and related industries. Hone Office, Rept. of Departmental Comm, to Consider Evidence qs to Occurrence of Epitheliomatous Ulceration Among Mule-Spinners, (London, 1926) Contains a bibliography on cancer among petroleum refiners. API 04639 -23' 50. Hunt, S. S , An Investigation into the Incidence of Cancerous or Frecancerous Skin Lesions Among Tar Workers in New South Wales. Med. J. Australia, 8.26.3 3 , 281-3 The general conclusion is that tar used in New South Wales for local road-work is not a serious danger. . . 5 1. I.P.T. Cancer Research Committee. Carcinogenicity of Spindle Oils, J. Inst. Pet. Tech., 2, 205 (1937) The I.P.T. Committee has not been convinced that the Bo-called incidence of cancer is in any Bhape or form connected with the use of spindle oils. . 52. International Labour Office. Carcinogenicity of Oils. Ind. and Labour Informa tion , u , 279 (1930) Tars at varying temperatures have been prepared to determine at what temperature carcinogenic compounds are formed, from which experiments it would appear that such compounds begin to be formed between 500 and 600, the maximum yield lying between 800 and 900 C. Attempt is now being made to determine fee constitution of a few apparently pure or almost pure compounds isolated from such tarB. Applying their standard test for determination of carcinogenicity, the staff found that olive oil, neats- foot oil, sperm oil were non-cancer producing and they have reason to suppose that natural skin fat is an important factor in the prevention of cancer. , 53. In tern atio n al LabourO ffice. "Occupation and H ea lth ", I , 5^7 (193*0? I I .' 837. 1156 (193*0 Before mineral oils came into vogue fee practice in textile millB was to use sperm, lard and neat's-foot oils and to some extent castor oil and colza oil. Henry states feat shale oil was introduced about 1850 and American petroleum oil about 186U, and feat, towards 1872, these oIIb were being used as components of spindle oil; also that Russian oil was first imported about 1880, Rumanian oil about 1900 and Persian oil about 1909. and all these were.used for this class of lubricating oil before fee war. During fee war Scottish shale oils naturally came more into use for lubricating purposes. Oil refiners have their own private formulae for mixings, but there is no doubt that the bulk of fee oil sold for lubricating spindles, during the past forty years has been principally made up of natural mineral oil. . According to fee 1929 report of fee Manchester Cancer Committee, in the distillation of tars, the carcinogenic products begin to form at a temperature ranging from 500 to 600 C. and reach a maximum at between 800 and 9p0 C. The addition of sulfuric acid at the time of use suffices to make the oils harmless without injuring or modifying their lubricating power. . . 5*+. In tern a tio n a l Labour Office 0cci9>ational Tumors. Suppl. to Occupation and H ealth , I . L . O . , Geneva, (Oct, 1939) Carcinogenic substances are discussed under the headings of hydro carbons, non-radioactive inorganic compounds, radioactive substances and radiation, and paraBites and microbes. Attention is called to the ab sence of any common physical or chemical characteristics shared by these various cancer-producing agents. API 04640 24- It 1b suggested that the cancer problem 1b essentially biochemical and that its solution will come with the discovery of the nature and cause of the intra-cellular chemical changes which follow the application . of a carcinogenic agent, , 55. Jordan, H. Experimental studies on the Production of'Cancer by Gas-works Tar, Z. Xrebsforschung, 1^, 39-55 (1922) Author has corroborated the work of others; in white mice treated with tar for four months err less, 100$ showed either cancer cr precancer- our changes. When the tar was distd. at U00 the volatile fraction did not produce these changes but the residue produced the typical prolifera tive changes in about f the tine required with the whole tar. No prolif eration could be produced with anthracene oil. Different nice showed a narked difference in the rapidity with which they developed proliferation with the same aot. of injury by the tar. Apparently the work was not followed to a point to det, just how many of the mice with precancerous changes would have developed actual carcinoma. . 56. Kennaway, E. L. The formation of a Cancer-producing Substance from Isoprene. . J. Path. Bact. 2J, 233-8 (192U) . 36a . Kawahata, K. Lung Cancer Among Generator-Gas Workers in the Steel Mills. Gann, 2, 367-88 (1938) . During the past $ years, 21 cases of primary lung carcinoma were observed among the generator-gas workers at the Tawata Iron-Steel Mills, These workers have av, service periods of 16 years, .In no other sections of the mills has such frequent appearance of lung cancer been noticed. The workers are expose^. to the spraying of gas contg, heavy dust. The inhaled gas contained about 0.7# of gaseous or. dust-like tar. Analyses showed creosote oil 2U.56#, phenols 0*31$, cresols 0,07#, naphthol U.65#, anthracene 2.00#, pitoh oil 62,67# and water 5.7U#, The metastases may appear very early in the brain, spinal cord and lymph nodes. The dura tion of lung canoer is very short, about 7 months. . . . 57. Kennaway, E. L. Cancer-Producing Constituents of Coal Tar. Brit. Med.J,, 56U- 7 (192*0 Cancer formation by tar products was investigated by author. Only higher fractions boiling at 25^-500> c * Were fo'md active in inducing cancer (creosote, green oil, crude anthracene and pitch). . 58. Kennsnray, E. L. Cancer-Producing Tars and Tar fractions. J. Ini. Hygiene U62-88 (192*0 Experiments on several thousand mice and analysis of a great mass of clinical records indicate that tar cancer, is caused by a very small Quantity of an unstable compound that exists in the high-boiling fraction (250 to 500) of a high-tenp. coal tar, i.e., creosote oil and anthra cene oil. Purified anthracene, like all other pure compounds tried, did not produce cancer. Splashing with hot, crude anthracene or creosote oils seems to be the usual method of contact. Shale oil produces cancer but is less active-tban gas works tar; crude petroleum is much less active; and blast-furnace tar (a low-temp, tar) does net produce cancer. The briquetting industry has reported more than.half of the known eases of tar cancer. Tar made by distilling coal at a low temperature (below 550) produces cancer very slowly or not at all. h?l 04641 '25-* ca, Kennaway, E. L. Experiments on Cancer-Producing Substances. Brit. Ued. J . , II, 1-^ (1925) . Cancer haB been produced in mice by substances obtained by heating CgHg, isoprene, yeast, human skin to temps, ranging from 700 to 920. A petroleum which produced no tumors of any kind in nice in a prolonged experiment showed very active cancer-producing properties after exposure ' to 880. 60. Kennaway, E. L. and Leitch , A. The Anatomical Distribution of the Occupational Cancer. J. Ind. Hygiene, J* 69 (1925) . 61. Kennaway, E. J. Further Experiments on Cancer-Producing Substances. Biochen. J., 2k, U97-50U (1930) Carcinogenic substances were obtained by the action at roontempera- ture of AICI7 on acetylene, xylene, naphthalene, naphthalene and brcmo- benzene and tetrahydronaphthalene, the last two being the most active. Two cancers were also obtained in a series of 10 nice painted with a soln. of 1 ,2 ,7 ,S-dibenzanthrecene. a-Phenylnaphthalene was prepared by action of AICI3 on CgHcpr and C ^ j . The distillates up to 3U20 C. containing the hydrocarbon were inactive but the residue in the flask was highly carcinogenic. Cyclohexane, cyclohexane, styrene, hydrophenamthrene, hydrochrysene, hydroretene, perylene, naphthalene and various naphthalene derivatives . all gave negative results. 62. Kennaway, 1. L. and Hieger, I. Carcinogenic Substances and Their Fluorescence Spectra. Brit. Med. J . , No. 3622, 10lh-6 (1930) This paper is a review of a large amount of work by the authors in an attempt to correlate fluorescence with carcinogenesis. Tar oils, spinile and shale oils, which show carcinogenic properties are also strongly fluorescent. . 63. Kewley, J. Cooperation. J. Inst. Pet. Tech., 18, 2U2 (1932) . Mention of the formation of a oommittee by the Institute of Petro leum Technologist! to follow the work of the Manchester Cancer Committee. Kling, A., Samssonor, N. and Beros, M. The Tarring of Highways as a Possible Agent in the Causation of Pulmonary Cancer. Bull. Acad. Med. 120, 130- **3 U958) . . Xxpts. in mice showed that the tar, as used on roads, produces cutaneous tumors and malignancy in the lungs. A substance contg. the bears (a) pyrene nucleus of decidedly cancerogenic properties has been sepi. from the tar, , Kling, A., Samssonov, N. and Heros, M. Possible Relationship between Tarring of Highways and the Increase of Incidence of Pulmonary Primary Cancer, Bull. Acad. Ued., 121, 78U- 9 1 (1939) Since tar contains benzopyrene, a recognized cancerigenic agent, it cannot be considered as inoffensive. Experiments on mice definitely con firm this assumption. API 04642 <26- gg, Koelsch, F. Cancer and Occupation. Monatschr. Krebsbekampf. 7 (1937) * The author, in the form of an abstract, presents a surrey of the relation between cancer and occupation. He includes bone cancer caused by radioactive substances, skin cancer from soot, tar, paraffin and lubricating oils (of which those boiling between 250-500 are of especial importance), skin cancer from arsenic as well as cancer and sarcoma from ultraviolet and sunlight. . . . 67, Kunae, G, Mineral Oil and Cancer. Chenu Ztg., 2, ^07-8 (1935) A study of,the map of Germany indicated that the number of deaths from cancer was always greatest in regions where mineral oil was,found, refined or used* While no definite relation is established, the author suggests the possibility of the existence of such a relationship. Further research.on this problem is indicated. It,is pointed out that mineral oil by itself does not cause cancer. It may, however, become one of the contributing factors, together with otfcerB. . , gg, Lane, C. G. Occupational Dermatitis. Arch. Dermatol, and Syphil. U3 , 1SU (19^1) . Describes the case of a 68 yr. old machinist who for 3 yrs. had a dermatitis of the face, arms, axillae and lower abdomen. There wore scattered areas of tan-brown hyperkoratotic follicles and follicular, plugs. Keratoses were presont on the scrotum and thero were keratotic areas on the arms. Aytopsy revealed carcinoma of the esophagus. Dr. Lane believes the skin changes to be due to oil to which the man was exposed in his Uo yrs. as a machinist, and that the condition is that described by Vhito among machinists, oil.workers and mule spinners in England. It apparently is rarely seen in this country, possibly because . oils employed here are less carcinogenic. 69. Lau.ber, B. J . , Hildebrand, Z. and Schocke, E. Possible Therapeutic Action of Carcinogenic Hydrocarbons in Treatment of Cancer. Z. Ges. Exptl. Mod., 370-9* (1939) Essentially last harmful therapeutic measures are available. The . dangers are demonstrated on mice treated with.methylpholanthrene, 70. Leitch, A. Mule fpinnars1 Canoer and Mineral Oils. Brit. Med. J . , 2, 9I+I-3 U92*) .. Rendered an inert California oil very active by heating it. (No details as to temperature, etc.). Crude ol)j3 from Assam, Borneo, Egypt, Burma and Badarpur produce malignant growths. Galician, Russian, Californian and Persian samples . were negative. 71. Lyth, R. The Relation of Carcinogenicity of Mineral Oils to Certain Physical and Chemical Characteristics of These Oils. J. of Ind. Hyg. 15, 226-37 (1933) . 72. Lyth, R. Molecular Distillation of Lubricating Oil. Nature, 139, 37U (1937) A briof report is givon of the distillation of a Scottish shale oii, using a specially.designed molecular still. The most striking result is the inversion in the change in the physical properties going up the tem perature scale, i.e., the first fractions show higher refractive indices and densities than the original oil, with gradually descending values from fraction four as the temperature is raised. Data on the properties API 04643 27- of the shale oil distillates are tabulated. These experiments are part of an investigation,of the interrelation of refractive index and viscosity to activity on injection, and thereby carcinogenicity , when applied to the skin. , 73. Mioscher, G.,.Almasy, F, and Zehender, Z. Is Thero a Connection Between the Benzpyreno Contont and the Carcinogenic Effect of Tar? Schweiz. Med. Wchnschr. ]1, 1002-7 (1^1) . The authors have examinod the benzpyrene contont of gas tar in various towns in Switzerland, using a method dovisod by Alnasy. Then the tars were purified and their carcinogenic effect determined by painting on mice. The investigators tried to evaluate the re sults by means of a statistical method in order to ovorcome the difficulty offored by the fact that many mice die in the long period needed for the experiments. They find a simple, regular relationship botweon the benzpyrene content and the carcinogenicity , of.the tarf 7U, Murray, J. A., et al. Discussion on Experimental Production of Malignant Tunops. Proc. Boy. Soc. (London) B113. 268-92 (1933). A symposium in which some attention is paid to carcinogenic , chon, compounds, and to tho iamunochemistry of cancer. 75. O 'Brien, H. P. The Problem of Cancer and Oil. Petroleum Times, 27, U62 (1932) . An open letter to the editor of tho Petroleum Times (London) in answer to an editorial in the issue of March 19th. The writer points out the humanitarian and scientific values derived from the cancer research of tho Manchostor Committee and criticizes the technological viewpoint of the editorial. . 76. 0 'Donovan, W, J. Cancer from Handling Anthracene Coke in the Dye Industry. Sr. J. Dema t . and 8pph., . . Three cases of cancer in a factory employing only 23 men. 77. Phillips, C. Helationship between Skin Cancer and Occupation in Texas: Heview of 1569 Teriflod Lesions Occurring in 1190 Patients. Texas . State J. Med., 6, 613-16 (19**1) 78. Prossor-fhite, B. "The Depnatorgoses" 199-238 (193*0 Dermatitis and caacor from petroleum products, shale and tars. , Excellent review. 80. Eoffo, A. B. Experimental Be search on tho Production of Pulmonary Tumors by the Distillates of Puel Oil. Presse Med., 538 (19U0) The author demonstrated ?n oil, taken from tho streets of Buenos Aires, identical to that from motor car exhaust, which con tains carcinogonip substances. Boffo had rats inhale the combustion gasos of fuel oil and later found a number of pulmonary cancers among tho animals. By injecting a distillate'of the fuel oil into . .the auricle of rabbits, he produced tumors In ED$>. 81. Boussy, G. and Oberling, C. Can Tarring of Hoads be Considered as a Cause of Pulmonary Cancer? Bull, Acad. Med. 120, 181-90 (1933) Tho danger is not considered to be of significance although the possibility is admitted. API 04644 -28- 22. Schreus, H. T. and Zurhelle, E, Experimental Production of Tumors with Tar9 from Various Sources and with Paraffin. Deut. Med. Wochschr. 49, 633--H (1923) . Author investigated the poisonous action of paraffin oil and tar constituents by painting mice twice a week. After six months a state of malignancy was obtained with paraffin o i l . Coal tar readily develops malignant tumors. Various purified acid and basic fractions from coal tar give negative results, The neutral tar oil is most offectivc as a tumor inducer. _ . . 23. Schwartz, L. Skin Diseases in Oil Refineries. Safoty Eng., 210 (Nov, 1934) It has been found that workers in oil refineries have a percentage above the average for carcinoma of the chock and of the lip . An unusual provalonce of pigmentpd papillomata on tho hands, forearms and legs of workers in oil refineries wd among machinists in contact with oil and grease was also noted. About 10$ of such workers were found to have th so growths. Tho use of totally enclosod manufacturing systems and of protective ointments is suggested. . 24. Schwartz, L. and Tulipan, L. "Occupational Disoases of the Skin", 1939 514. 85. Scott, A, Occupational Dermatosos of the Paraffin Workers in Scottish Shale . Oils. Brit. Med. J., S.2 8 .2 2 , 3 SI- 5 . 26. Sequoira, J, E. Cancer and other Diseasos of the Skin Caused by Minorai Oils. , Konya qnd E. African Mod. J., 6 , I8-23 (1929) . 87. Smyth, H. E. Review of Literature for 1926-1934, inc. Report of Committee on Industrial Skin Irritants to im. Public Health Assn. . 82, Souths m and Wilson. Cancer of the Srotun. .Brit. Med. J,, 2, 971-3 (1922) 89. Speaknaa, J. 3. and Chamberlain, N. H. Trans. Taraday Soc., 29, 367-- S (1933) la a study of the carciaogonic ptency of mineral oils, Twart has shown that the addition of glycerides reduces their potency, althou^. no . oil furpassos lanolin in this respot* . ., 90. Toleky, L. Occupational Caacor. Acta d. Internat. Ver, f. Krebebekonpfusg, l, 253-75 (193S) Several isolated cases of lung cancer among generator workors have boon reportod and among works oxposod to coal dust, tar and tar iistil- . latos, but tho number is small. 91. Toutschlaonder, 0. Industrial Cancer, especially tho Types Occurring in Germany. Z. fuor Krebsforsch. 2, 6l4-27 (1930) Discussoe x-ray cancer, cancer of briquetto workers, mulo spinnors1 cancer, which has not appearod in Germany, and paraffin cancor among tho so who work in the petroleum industry. 92. TerutacHlaQiiAor, 0. Occupational Cancer, with Spocial Consideration of its Prevention and legislation on tho Subjoet. Med. Walt. 11, 1267-72 (13^1-5 (1937) Occupations in which there is danger of development of cancer ore reviewed; many data are given regarding substances considered carcinogenic, API 04645 29- the location of malignant tumors, their latont period, protective measure of an Industrial-hygienic typo, questions of insuraaco, otc. There ia no sp. agent connon to all carcinogenic substances as a pronoter of cancer growth. , Teuschlaondor, 0. Does Tar Require Ultra Violet Light to Produce Skin Cancor? Klin. Wchnschr., l6, 12SU-5 (1937) Whito nico wore paintod with tar. Cancers developed not only in the irradiato! anials but also in thoso kopt in a dark chamber so that not only a preparatory but also an independent cancorogenic effoct nust be ascribod to $ar. . . . Toutschlaender, 0. Light and Skin Cancer. Ztschr. f. KrobBforsch. 0, 81-92 (19^0 ) . The author investigates the problon of iriiethor cr not a photodynamic influence is necessary in tho genesis of tar cancer. Ho conducted ex periments on tarred nice kept ip a dark roon. Since skin cancor developed on tho painted skin, it is evident that ultra-violet light is not a requisite in tar cancor genesis. The sane is shown by the development of spontaneous skin caacors in two wild groy house nice that lived in a briquet factory. .Noverthelosa there is a widespread belief that both cancer of radiant source sad tar cancer of the skin are caused by cyclic hydrocar bons. According to Saffo, both typos are originato! by oxidation and deconpositien of oholesterol |n the tissues which nay be causo! by radia tion as well as by chonical influenco--cancer-provoking cyclic hydro carbons aro finally generated. Prophylaxis oust, therefore, guard against tho influence of on? or both factors. ... . Touralno, A. and Bo u t , H. Cancer fron Lubricating Oils. Rev. Mod. Franc. 20, 285-92 (1939) - . A very complete review of cancor fron lubricating oils, its occur- ronco,,clinical symptoms and tho medico-legal aspects of erud.cases. Twort, C. C. and Zsg, H.R. Mulo Splnnors' Cancor and Mineral Oils. Lancet 1, 752 (1928) . . . . " Twort, C, C. and Fulton, J. D. xporinontB on the Nature of the Carcinogenic igeats in Minorai. Oils. J. Path, and Bacterlol., 2, 1U9 -16 1 (1929) Fron a consideration of the cheoical reactions involved, tho authors are of the opinion that it is to bonezonoid hydrocarbons that cortain mineral oils owe their carcinogenic properties. Treatment of tho oils with sulfuric acid led to almost total abolition of their car cinogenic properties, and similar rosults were obtained by the adoption of methods of oxidation.and reduction. . Twort, C. C. and Twort, J. M. Studios on tho Origin of Cancor. Ztschr. f. Krebsforsch,, 2, U 91 (1930) This is a general survey of the work of the Tworts, and 1s based on esqperimeats oa ^5,000 alee, & smaller number of rate, guinea-pigs, and rabbits, and on the use of some hundreds of varieties of tars oils of various capacities to cause cancer. There is but little probability that an acquired physiological immunity against cancer-producing sub 8tancos orlate. Tho authors1 various substances are divided according to their API 04646 *30- 99. . 100. cancer-forming capacity in mice, so that every group has about ton times the power of the preceding ono. Twort, C, C. and Twort, J, M. Classification of Four Thousand E^erimontal Cil and Tar Skin Tumours of Mice. The study from which this classification was made was based upon 2 9 ,100.a n i m a l s . , Twort, C. C, and Fulton, J. D. Further Experiments on the Carcinogenicity of Synthetic Tars and Thoir Fractions. J. Path. Bact. H 9-U3 (1930). 101.. . Twort, C, C. and Twort, J, M. The Carcinogonic Potency of Mineral Oils. J. lad. Byg. 1, 20^-22 6 (1931) . Painting mice with refined shalo oil induces cancer more roadily than painting with refinod potroleum well oil. The most potent fraction from shalo oil is unfinished lubricating oil from which most of tho paraffin wax has boon removed but which had not been treated with EgSOi; and filterod. Tho 'heavier grade oils aro lest potent than spindle oils. The Cancer-producing property of oils appears to bo relatod to fluores cence. Oils having a bluo fluorescence soem more active than thoso having a groon fluoresconce. Chrysone dissolved in olclc acid posseBsos carcinpgonic properties, 102. Twort, C. C, and Twort, J. M. The Bolative Fotoncy of Carcinogenic Tars and Oils. J. Hyg., 29, 373-9 (1931) . A mothod h a e b o o n devised whoreby the potoncy of any given carcino gonic agent can be compared with that of a standard agent. A unit of carcinogenicity- TJX. - has been established, and a concentration of 500 carcinogenic units por cubic centimeter Is considerod to induco the maximum rolatlvo rosponse In a niaals whom tho agent is appliod twico a week. The carcinogonic powors of oils rato as follows, in descending order; Shale, Yonesualan, B o m o o , Bunanian, Persian, Californian, Mexican, Mid*Xontinental, Texan, Pennsylvanian, and fiuasiaa. Byppthotical standard agent Pena, pdl Cal. pet. oil Oil Bo. 3 Shale Oil Pitch Gas tar Pinepo synthotic tar Effect of refining Ponn. pil Mothyl sulfite oxtract Oil Bo. 3 ' Distillate 300-380C./I2nn Methyl sulfite oxtract Shale oil Oxidized at 150-l0 C . Pinono synthetic tar concontrato Oxddizod at 100C. Cxiiizod at l`SO-l6oC. 100,0 0,1 3.* 0..6 Ug.o 25,0 9^*0 7060 . 0,1 22,0 0,o 12,0 53 Ug,o 0,3 37^5.0 2369.0 58.0 API 04647 '31- . -O Twcrt, C. C, and Pulton, J, D. Concentration of the Carcinogenic Principle in Oils and Tars. J. fuer Krebsforsch. 2i 5U3-73 (1932) In tho attenpt to assess U.C, by physical and chemical characteris tics, the specific gravity, refractive indo* and iodine nunber appeared cost promising, though other features nay also ultinately prove to be of value. 10h ' Twort. C. C. and Lyth, R, The Selection of Non-carcinogonic iron Carcinogenic Oils. J. Hyg., 21, U6lt-73 (1933) All the animal and vegetable oils tested by tho authors on aninals have proved to be incapable of inducing tunor formation during the life of their aninals . On the other hand, oleic acid and linolcic acid, unsaturated fatty acids which nay be present in comercial saponifiable oils, have frequently induced tunor formation; observations which in thoir opinion are of the highest importance in relation to nany cancers other than those of tho skin, and possibly even of those of the skin it self. It has been found that the carcinogenic constituents of a given crude are not equally distributed in the various products of distillation obtained iron this crude. The activity of the first products to cone over in tho still, the notor spirits, etc., is negligible, and that of the lonp oils, burning oils, light fuel, ftc., is also of little account, but when we reach the boiling rango of tho lubricating oils a definite carcinogenic activity nay bocone manifest. Among the latter the most active grades are, on the whole, the spindle grades, closely followed by oils of a Redwood yiacosity of 500 to 1500 at 70 P . , with a gradual docroase in activity as one approaches the internal conbustion engine (notor car) grades. The crude oils themselves, as a rule, aro somewhat less potont than the motor ear oils, but of course, it will necessarily depend upon tho amount of refining to which the latter have been subjected . bofore.being marketed . ' . 105. Tnort, C. C. and Twort, J. M. Carcinogenicity of Spindle Oils. Oil and Colour Trades J . , 2, 1193-4 (1937) . A physical aSS an a n i m l test for oarcinogenicity and a physical and an animal t?st for deroaticity of mineral textile oils are described. The average results of these tests on 66 oils (excluding shale oils) collect ed 3-10 yrs. ago and on 66 oils collected recently are tabulated (The animal test for carcinogenicity is not yet completed for the recent oils) These results Indicate that the original oils are definitely worse than the recent oils in both the dermatitis tosts, while in the cancer physical test there is no significaht difference. It is expected that the figures for the' recent oils in the animal tost of carcinogenicity will be lower than these of the original oils. -- - It is concluded, however, that little is being dono to improve mule spindle oils from the biological standpoint. There aro also indications that the average oil used in some of the cotton-spinning towns is more , dongorous than that used, in others. , 106. Twort, C, C. and Twort, J, M. Notes on Sone of tho Procedures Adopted for Assoasing 251-5 ( s) the Biological 193 Activity of . Mineral Oils. Oil. ` Colour trades J., Mineral oils may induce dermatitis or cancer of tho skin. In dotg. tho carcinogenic aspect 3 essential detaa. are nade: d . , n and kinetic 04 648 API -J3- . 107. . 108. . viscosity (KV) The data collected are based on the utilization of. formulae for assessing the biol. activity, especially from its carcino genic aspect. In Formula A, R = (n-l)/d where R = sp. refractivity, n = refractive index and.d = density. In Formula B, R = n-(d/2). Formula A i s used in obtaining the cancer r e fr a c t iv it y CR from Formula C which i s CR = Re 3(d-0.900)/20. In Formula D the refined cancer re f r a c t i v i t y RCR = CR - (KV/50) . R e s u lts , whero thpso minoral o ils have bpon enployod, are shown in tables in which mineral o ils are grouped according to to x ic ity and according to the n drop* Tho sign ifican ce o f d. in ro latio n to tho n drop among o ils o f sim ilar to x ic ity and the sig n ifica n ce o f v is c o s ity in re la tio n to tho n drop among o i l s o f apparontly sim ilar to x ic it y aro Bhown. Tho re a l d i f f i c u l t y in a rr iv in g at tho truo b io l. a c t iv it y with greater accuracy is the lack o f uni form ity p f tho in e rt f u l l y hydrogenated c o n stitu e n ts. There is quite good correlation betweon caro in ogo n icity, r e fr a c t iv it y , n drop and toxicity. ' . Twort, J. M. and Xyth, R. The Concentration of Carcinogenic Materials in Minoral O ils by D is tilla tio n Prccessos. J , Hyg. l6 l-9 (1939) Twolvo acid-treated lubricating cuts of a crude, Borneo mineral oil, wore testod for carcinogenic activity. Tho whole range was bio logically active, which activity had boon foreseen from an examination of tho physical characteristics. Tho pook activity was around a vis cosity of 200-250 Centipoisos at 25 C. Molecular distillation gave a groater concentration of the carcinogenic material than ordinary dis tillation at from 3-10 nn. In confirmation of previous findings, the middle fractions of s B o r n s o crudo.oil were mostly responsible for pathological ohanges in tho organs-- fatty infiltration of th6 livor and hyaline degeneration of tho spleen. Long tumors wore nora prevalent than is usuai when this type of agent is usod for testing carcinogenity for tho skin. Thai? incidence was rathor higher in the more viscous fractions: this inoidonoe was apparently not correlated with carcino- gonity. for the skin Twort, J , M. and lyth, R . ' Skin Cancer due to Handling Coal Tars Usod for Prosprvatlon of Tifhing Sets* Nature, lUH, UH6 (1939) Several fishermen contracted cancer of tho skin after.handling the tarB. Mouse eapts, showed that different coal tail differed in their ca rcinogonie activity, although all producod some cancers. Creosote oil and anthracene oil wero also carcinogenic. Only coal tar made in vortical low-temp retorts should bo used on nets. . 109. Twort. 0 Gv Mttle-Gpinnors * Cancer: The Mood for Using the Correct Oils. 011-oolourTrados J., S,29.kl, 326 The cancer-producing powers of mineral oils used in the cotton industry from dlfforont fields of origin, in tho crude and rofinei statos, wero thoroughly arani nod and tho rosul ts showod that .there is a dangor of any one producing cancer of tho skin If appliod long enough but tho oils from oortain fields are tho more likoly to do b o . Special attention was paid to the examination of the physical characteristics of various mineral oils, and it was proved that a Imowledgo of their refractive Index and viscosity provides a more reliable estimate of their cancer-producing powers than the application of tho Banplo to the skin. This test is accurate, rapid and inexpensive, while that with tho Bkln is variable, lengthy and costly. API 04649 ,63 The chiof lino of investigation has boon a continuation of tho work on tho nolocular distillation of nineral oils with tho objoct of isolat ing tho substancos responsible for thoir carcinogonic activities. Animal experiments with fractional distillatos iron a Venezuelan oil aro in progress. Fractions obtained by nolocular distillation of a carcinogonic shale oil have boon subjected to qhronatographic absorption and two apparently puro hydrocarbons havo boon isolato! in snail quantity; those aro l?eing investigato! chemically. Painting experiments with fractions obtainod by this nathod havo shown that nany of than aro highly toxic for nico. None of the substancos so for tostod has boon shown to possess a high carcinogonic activity. i. few spindle grade oils and threo oils intended as vohiclcs for lnsocticides havo boon tosted for carcinogenicity. A.colloidal matrial intendo! aa a protective against carcinogonic oils has boon tosted. Thero aro indications that it has sono protective action. 110. Tho carcinogonic activity of two products f o m o d during the purifi cation of carbonisation has boon tosted, and found to bo loss than that of tho average gae tor. . Ullnann, K . , Opponhoin, U. and Siilo, J, E. J. Ind. Hygiene, S, 288, 36H (1926) " ' Tho lpsions caused by crude potroleun are the sane as tho so caused by crude coal tar, showing the analogous substancos must bo present in >oth. The final products of distillation aro tho most active, especially paraffin oil. Tho carcinogenic agent is presont in fractions fron 200 0. to U500 C., but it is not cortain that tho sene substance canapa both d o m a t i tie and api the Ilona. , , 111. . Valado, P. Cancer of tho Hucan Inng iron Dust fron Tarrod Soads. Presso Mod., 2.1 .39, l6l . . . . 112. . Von Thordscho, M. X. Chanical Cancer. Ing. Chin., 20, 3" 5 (193) Moro than twioo ae naay easos of cancer duo to soot wore found among swoopere than raoag any, other occupation Personal cloanllnoss and clothing that fits tightiy'around the oxtrenitios and around tho nock arc the tee) preventiva#. e m i A r care will do nuch toward preventing cancer due to exposure to gasoline and its derivatives, paraffins, o IIb , and greases. Such precautions are ovon nore nocoesary in cases exposed to tar, pitch, rosin or aniline dyos. Strict nodical sup erviBion and tho uso of processes which avoid contact of tho workers with tho product will further-reduce the danger. . . 113. Wampler, P. J. Occupational Diseases of the Skin (by L. Schwarz). "Indus trial Medicine" , 19U3 , 327-9 Chimney sweeps1 cancer has been reported in England more frequently than in any other country. It is said that the incidence of cancer among chimney sweeps is eight times more common than among the general population. Ca ncor of tho scrotum of chimney swoops, however, is on tho oclino In England and it is reported as being practically non--existoat in othor countries, except for an isolated cas$ or two in Germany. Tho local irritation and rubbing in of the Boot as the swoop is cramped in descending tho chimney is said to bo tho cause. AP I 04650 f "Or* Car is usod in building roads, in making roofing paper and folt. Pitch is used for making conduits, lacquers, insulating matorial, groasos, and mloctal cements, and workers at thoso occupations aro affoctod with comedonos, tumors, warts, koratoses, and oplthelioma, mostly of the scrotum, lip, face and hands* No cases of mulo spinners' cancer havo toon roported from Franco, Germany, Russia, or Poland. Tho author nado examinations of thousands of nulo spinnors employed in tho Unitod States and did not find any casos of scrotal cancor, a l t h o u ^ thoro wore maiy casos of folliculitis and fcoratoaos of tho thighs caused by oil-soaked trousors. . , llU. War-iok, H* Molanodorma and Keratoses from the Action of Asphalt. Arztl. Sachverst. Ztg., 66, U9 (19^0). In th? preparation of cork plates (heat-insulation plates of asphalt and cork) much dust develops under very unfavorable working conditions. Two wprkors, who had boon working for threo months, suffored from pignontation, inflammatory changes and hyperkeratoses of the face, forearms and hands. Tho hyperplastic procossos wore.intensified in the older workers. The symptoms wore aggravatod by light. The intonsive action Qf asphalt dust is considered to bo tho cause. 115. Vatson. A. 7.. Tar Cancor in Mice, III, An Apparatus for tho Preparation undor Standard Conditions of a Hi^ily Potent Carcinogenic Agont of Low Toxicity. Brit. Jour. Ixpor. Path., 12, UhL-7 (1931) . With an ada ptation of the apparatus of Hague and Whooler tho author has succeeded in making from purified turpentine, at 850 C. a relatively aon-toxio tar which ollcitod tumors after 210 days in 90$ of tho survivors from a group of 37 nice; most of these growths were malignant. . . . Wolwart. Cancer from Paraffin fax and Mineral Oils. Soifons. Ztg., 62, 792-3 (1935) Most chemists and dermatologists boliove that workora in paraffin factprlos got cancor from the paraffin itself whilo Schorbor and Tcutsch- laender claim that cancer ices not cono from paraffin but from mineral oil*. . . . . TTindaus, A. and Bennhak, 3. Some Derivatives of 3 ^Benzopyrene. Z. Physiol. Chon. 2U^, 256-66 (1937) By analogy to xrays (-rays produe0 and x-rays euro cancer") , carcinogenic hydrocarbons should bo tested for possible thorapoutic values. Suggos tive rosul ts have boen obtained with 3,U-bonzopyrnet(I). * i7ooi, 7. C. The Hon-Carcinogonic Nature of Furifiod Mineral Oils. J. An. Mod. Assn., 1, l6Ul (1930) ' Tho gonoral clinical ovilenco that thoye exists no rolation botwoen tho therapeutic use of refinod potroleus products and the occurronco of cancer is confirmed by e^erinental studies. , Wood, H. B. Paraffin Not Productive of Cancor. J. Cancor Eos., 13, 97-102 (1929) . . 1 ~ool H. B. Skin Losions Anopg Tar Workors. J. Cancor Eos., 1J, 5U- 9 (1929) Different typos and composition of tars are discussed. Only tar obtained from tho distn. of coal at high temps, contains a substance API 04651 -38** carcinogenic to certain lab. animals. Workmen handling coal tar showed . tar warts as a result, hut no other effect. No irritant action on the human skin was found from low temp, distillate tar or from.petroleum, tar, 121, 122. Woodhouse, D. L. Carcinogenicity of Synthetic Lubricating Oils. Fet. Tech., 20, 1057-63 (193*0 J. Inst. . Yamagiwa and Ichikawa. Experimental Study of the Pathogenesis of Carcinoma. J. Cancer Res., Ill, 1-21 (191$) In 1915 produced cancer by the experimental application of tar to the ear of a laboratory animal. API 04652 .4 FOR INFORMATION ONLY - NOT FON PUBLICATION A CONTRIBUTION OF INFORMATION TO KFBFR3 OF A.p.I. JUDICAL ADVISORY C07TTTZE SHELL OIL COMPANY, INCORPORATED WOOD RIVER RESEARCH LABORATORIES REPORT NO. M-12^7 JULY 2, 19^5 SUBJECT: CABCCTOGBUC HYDROCARBONS AND RELATED COMPOUHDS A LIBERATORS REVIEW AUTHOR: H. H . ZUHBMA Exportation of This Report Is Subject to License Uhder the National Defense Act SHELL O H COMPANY INCORPORATED WOOD RIVER RESEARCH LABORATORIES REPORT NO. M-12^7 JULY 2, 19*0 SUBJECT: CARCINOGENIC HYDROCARBONS AND RELATED COMPOUNDS A LITERATURE REVIEW AUTHOR: H. H. ZU3HEMA Industrial cancer vts first recognized In England In the latter part of the eighteenth century, when it was established that chimney sveeps were particularly liable to cancer of the scrotum.ic This was caused by soot. Progress In this field of study was very slow at first, and It was not until 1915 that two Japanese Investi gators announced the first case of carcinoma in an experimental animal. They produced first papillomas and then true cancer of the epidermis on the ears of rabbits by painting with tar over long periods of time. JS During the thirty years that have elapsed since that discovery, a great deal of work has been done with various coal tar and petroleum fractions and pure compounds either occurring in these fractions or prepared synthetically. Numerous species of tost animals, Including mice, rats, fowl, rabbits, and dogs have beon used, and many methods of application, Including oral administration, Intramuscular, Intravenous, and subcutaneous Injection, and painting on the skin. The method that appears to. be the most widely used at present consists of painting a solution on the skin of a special In bred strain of sloe. Mice are preferred over animals having longer life-spans since they respond more rapidly. The special strains are used to increase the precision of the test. Painting Is preferred to other methods of application because there la less likelihood of Interference by simultaneous spontaneous carcinomata. The carcino genicity of a given ocopound is Influenced by many factors Including the genetlo constitution of the animal species and strain, Its age and sex, the diet, the physical condition of the animal, the purity of the compound, the dose, the physical state of the compound, the solvent used, sad the route or site of application. 2 5 While carcinogenic properties are generally associated with certain polynuclear aromatlos and their derivatives, there are many substances entirely unrelated to these compounds which have been re ported as having similar cancer-producing ability. Among these may be mentioned asbestos314" 37 , Inorganic compounds of arsenic end of zinc2 ', aqueous potassium hydroxide end aqueous hydrochloric acid25, ethyl alcohols, glucose2 5 , fructose25, sad a number of nitrogen compounds, most of which contain one or more benzene rings25. Radio active elements and compounds are not Included in this discussion since the mechanism of their producing cancer Is probably quite different, i.e., physical rather than chemical. Materials which havo been roported A P I 04654 B eport N o. M-12*+7 2 as carcinogenic and whose carcinogenicity Is probably due to the prejence of polynuclear aromatics Include coal tar and pitch2 6 ' 27 blue shale oil5, mineral oils and asphaltu~, tobacco tar39, tars obtained in the destructive distillation of teau2and coffee110, diesel fuel52, distillates from Borneo crude petroleum54, combustion gases from fuel oil"1, the SOo extract from a spindle oil produced from a paraffinic crude petroleum5", the products obtained by heating acetylene, lsoprene, yeast, a non-careinogenic petroleum fraction, or human skin to' 700 - 900C*>, and the products obtained by treating acetylene, xylene, naphthalene, or tetrahydronaphthaleno vith aluminum chloride3 . The carcinogenicity of tars produced by heating various substances tends to increase with increasing temperature. 3 us it is probablo that the carcinogenic hydrocarbons present in certain coal tar and petroleum fractions were to a large extent formed during the process steps and were not present in the coal or crude petroleum from which they were derived. However, the carcinogenicity of a given fraction depends upon the source as well as the method of processing, ccording to the Manchester Committee on Cancer"9, the following order of increasing carclnogenlolty prevails: Bus alan, Pennsylvania, Texas, Mid-Continent, Mexican, California, Persia, Romanian, Borneo, Venezuela, and shale. This corresponds roughly to the order of Increasing aromati city. . A large number of compounds have been tested for carcino genicity. Hartwell has published a survey29 which includes 696 compounds tested. Of these, 1U6 were carcinogenic, and 23 additional ones produced papillomas but no true cancers. While some of these compounds have been tested under only one or two sets of conditions, others have been studied very extensively. The three compounds that have received the most detailed study are the three derivatives of 1 , 2 -benzanthracene: 1 ,2 ,9 ,6-dlbeosantfaaoene, 3 ,^-benzpyrene, and 20- methylcholanthrene. All three arc potent carcinogens. It has been estimated that they have been investigated In 60 different labora tories. 20 A list of most of the known carcinogenic compounds Is given la Table l.pcgce 5-J. Structure, complete with numbering systems, are Included, since lack of uniformity among various in vestigators la this field has led to some confusion. There Is fortunately less deviation In the current papers than In the case of those written ten to fifteen years ago. The numbering used In this report corresponds to that used by Hartwell25. It should be understood that the carcinogenicity of the-oompounds shown In Table 1 varies considerably In degree and that the results have been verified by several laboratories In some cases while In others the results of only one or two experiments are available. The reader is referred to Hartwell for more detailed information and for re ference to the original experiments. It will be observed that most of the compounds are either hydrocarbons or their derivatives containing at least three benzene rings or nitrogen compounds con taining at least two benzene rings. More specifically, the first of these classes consists, with only throe exceptions, of derivatives A P I 04655 Report No.. M-12b7 3 of phenanthrene. The exceptions are tetraphenylmethane, triphcnylbenzene. and trlphenylethylene. In Table 1 the hydrocarbons are subclass Lfled. further as derivatives of 1 ,2-benzanthracene, 3 ,b-benzpyrene, cholanthrene, and other derivatives of phenanthrene. Examination of the structures shows that all of these are derivatives of phenanthrene. While the work that has been done on the production of cancer by exposure to various compounds has made it possible to draw certain conclusions regarding the effect of chemical structure, It Is not as yet possible to predict with any degree of certainty the carcinogenicity of a given compound from its structure. A phenanthrene derivative may or may not, for example, be carcinogenic depending upon such factors as the length of an alkyl side chain, ^he position of a benzene ring, or tho position of an alkyl group. However, a paraffinic or naphthenic hydrocarbon or one containing only one or two bonzeno rings may with a reasonable degree of confidence bo assumed to be non-carcinogenic. The amount of compound required to produce an experimental cancer on a test animal Is surprisingly small. Coses of 1,2,^,6-di benzanthracene and 3 A-benzpyrene as small as 2 .5 and b micrograms, respectively, give positive results when applied to mice.^-'Discontinuous application, e.g., once a week, of a given total quantity of material is moro effective than continuous exposure.15 A single application of 20methylcholanthrono in 0 .6^ benzene solution is capable of producing cancer on the akin of mice. U3 lbea different carcinogenic hydrocarbons, e.g., methylcholanthrone, benzpyrene, and dibenzanthracene, are applied successively the effeot is additive33. The investigators who made this observation offer the hypothesis that carclnogenlsls is essentially an acciznulatlon of abnormal protein within the cell. Since ao many compounds have been tested for carcinogenicity it is only natural that several attempts have been made to correlate this property with other properties, either physical or chemical. Such a correlation would be extremely useful in that the determination of the physical or chemical property would be much simpler than the rather long and tedious prooeas of exposing experimental animals to the substanoe in question. Fluoresoenoe spectra have received more study in this regard than m y other property P . 7 . 88 *T5ie author of a reoent paper made the statement that all known carllnogenic chemicals are fluorescent.115 However, it is obvious from a glance at Table 1 or Hartwell's tabulation that this is too broad a claim. However, many investigators have used fluoreaoenoe spectra to good advantage in this field, and there appears to be a definite correlation with carcinogenicity, at least with certain types of compounds. The correlation may be due in part to the fact that fluorescence spectra have been used as a guide in selecting fractions from coal tar for physiological tests; it is conceivable that other carcinogenic com pounds, which ere not fluorescent, exist or could be synthesized. A rough parallelism between the carcinogenicity of poly nuclear aromatics and the diazo coupling reaction has been observed.2 1 . 22 Attempts have also been made to correlate refractive index, or more specifically, specific refraction, with the carcinogenicity of oils. API 04656 Report No. M-12^7 k The Manchester Committee on Cancer45 recommended that spindle oils of various ranges of specific gravity have specific refraction values below certain limits to assure the absence of carcinogenic properties. However, It Is obvious that thore can be no general correlation between a physical property of this nature and carcinogenicity, for slight changes In structure, such as the position of a methyl group, which would have little effect upon optical properties, affect carcinogenic properties profoundly; furthermore the presence of a large concentra tion of a non-carcinogenic aromatic would raise the specific refraction of a mixture much more than would the presence of a small amount of a potent carcinogen. The probability of obtaining a general correlation between carcinogenicity and some more easily determined property would be greatly enhanced If there were a clearer understanding of the mechanism of the action of carcinogenic compounds. It is, of course, very difficult to obtain such an understanding, for so little is known . about cancer itself. Whether or not carclnogenlsls by hydrocarbons and related compounds is in any way connected with spontaneous cancer is a question that has received much conjecture. That such a relationship does exist is suggested by the fact that certain derivatives of estradiol (see Table 1) which la closely related to the sex hormone estrone, are carcinogenic. Spontaneous cancer quite often occurs in the reproductive organs. Furthermore, the very potent carcinogen, 20-methylcholanthrene, can be produced by the degradation of dee- oxychclio acid, cholic acid, or cholesterol, the first two of which are normal constituents of human bile and the last of which is present in all tissues of the human body.2*2 These degradation reactions were, however, conducted under drastic conditions which are In no manner related to those prevailing physiologically, and there is no evidence that 20-methyloholanthrene Is formed in the body through the degradation of bile acids or cholesterol. The possible connection between cancer produced spontaneously and carclnogenlsls by methylchclanthrene or alated compounds therefore remains a matter of conjecture, at least for the present. There has, for obvious reasons, bean little attempt to Induce cancer in human beings through exposure to the various com pounds that are carcinogenic to mice. There is, therefore, no direct correlation between the susceptibility of man and the test animals. There is, of course, an Indirect correlation of occupational cancer largely through exposure to coal tar and dye intermediates caused by materials which are carcinogenic to mice. However, many of the compounds shown in Table 1 do not occur in any products known to have caused occupational cancers, wnfl it is conceivable that some compounds harmful to mice are innocoue to man. until that can be proved, the only safe policy is to regard all compounds which are harmful to mice as dangerous and to avoid exposure by humans. EEZ:VAC AP I 04657 Report No. M-12 ^ 7 5 TABLE 1 CARCINOGENIC COMPOUNDS All compounds listed by Hartwell25 unless otherwise Indicated. The following derivatives of 1,2 -benzanthracene: 3-methyl 5- methyl 6- methyl 9-methyl . 5-ethyl 10- ethyl 5-n-propyl 5-n-butyl2 5-n-amyl2 5- n-hexyl2 6- i-propyl 3-hydroxy 10-hydroxy f 10-aldehyde, -C 0 ? 10-methyleneaoetoxy, -C-O-C-CH^ I 10-methylenecarbomethoxy, I 0 -Ci-C-O-CH3 I H i 10-cyanomethyl, -C-CN H 3-methoxy 10-methoxy U, 9-dimethyl 4 ,10-dimethyl 5.6- dimethyl 5.9- dimethyl 5 4-0-dimethyl 6.7- dimethyl 9.10- dimethyl 6.7- dimethyl 9.10-dlmethyl 5-chloro, 10-methyl 7-chloro, 10-methyl 5-cyano, 10-methyl 7-cyano, 10-methyl , 1,2,7,8-dibenzanthracene31 1,2,5,6-dibenzanthracene API 04658 t Beport Ho. M-12U7 The following derivatives of 1,2,5,6-dlbenzanthracene: 9-methoxy 2' -methyl 3' -methyl h-methyl 6 SEE 5.6- cyclopenteno -6-C-(j- HSH 6.7- cyclopenteno 1' ,2 ',3 ',h' -tetrahydro- 5-aldehyde 1<.'-methyl 5-methyl 1' , 2 ' -dihydro, h'-methyl 3. Derirativee of Cholanthracene 1' ^'^'j^'-tetrahydro 10-acetyl 3, h,8,9-dibenzpyrene 5,10-dihydro-3,^,8,9-di benzpyrene 7-methyl,1,2,3,h-dibenzpyrene Cholanthrene The following derivatives of cholanthrene: 20-methyl 20-ethyl 20-isopropyl 20-tert-butylJ u 1 5 .20- dlmethyl 16.20- dimethyl 15-hydroxy, 20-methyl 15-keto, 20-methyl API 04659 Itep e r t No. M -I2 U7 7 k. Other Derivatives of Phenanthrene Colchicine The following derivatives of 3 ,^-benzphenanthrene 1 - methyl2 2- methyl2 2-ethyl2 2-isopropyl2 7- methyl2 8- methyl2 2 ,9 -diethyl 2-methyl, 1 ,2 ,3 A - dibenzphenanthene Cholesterol oleate l,2-4inethyl chrysene2 5-methyl chrysene17 5 -methylene chrysene17 5 ,6-dimethyl chrysene17 A PI 04660 Beport No. M-I2U7 Eguilonin benzoate Estradoil caprylate I 0 CHj-(CEa)r,~C-0' 1 ,2-cyolopentcne phenacthreno2 GH T j Estradiol 3-n-butyrato, 17-bcnzoate 0*0 CHj-(CEa)s-i-0 5. Other Aromatic Compounds Te traphenylmethane 1 ,3 ,5-triphenylbenzene Triphenylethyleno 3Z Report No. M-12Vf 9 6. Organic Compounds Containing Nitrogen 2-amino, 1-naphthol Alpha naphthylamine13 Eeta-naohthylanine 0 OH Acetylcholine, " i CH3-C-0 -CH2-N-(CH,)3 o-amimo < azotoluene /-- p-dimethyl aminoazobenzene (butter yellow) / - r S -\ ./ ')-K (CH -'2 I H Syyryl ^30 .API 04662 Report No. M-12^7 1 ,2,5 ,6-dlbenz acri d Lne 10 1 ,2 5 ,6-dibenzcarbazole 1 ,2 ,7 ,8-dlbenzacridine 3 ,^,5 ,6 -dlbenzcarbazole 7 Mlscellaneoua Arsenic trloxlde Potassium arsenlte Aqueous hydrochloric acid Aqueous potassium hydroxide Zinc chlorlds Zinc sulfate Ethyl alcohol Fructose Glucose Galactose A P I 04663 Beport No. M-1247 BIBLIOGRAPHY 1 . Auld, S. J. M., J. Hist. P et. Tech., 24, 577-33 (1936). 2 . Badger. G.M., Cook, J.W., Hevett, C.L., Kennaway, E.L., Kennaway, ' N. M., Martin, R.H., and Robinson, A.M., Proc. Roy. Soc., B129, 439-67- (1940) 3 Badger, G.M., Cook, J.W., Hevett, C.L., Kennaway, E.L., Kennaway, N.M., and Martin, R.H., Proc. Roy. Soc., B 1 3 1 , 170-82 (19^2). L. Barry, 0, Cook, J.W., Haslevood, G.A.D, Hevett, C.L., Hieger, I., ' and Kennaway, E.L., ibid, B-117, 313-51 (1935). 5 . Berenblum, I., and Schoental, R., Brit. J. Exp. Path., 24, 232-9 (19^3) 4 6 . Bottomley, A.C., and Tvort, C.C., Am. J. Cancer, 21, 781-3 (193^) 7 . Bruce, W.F., and Todd, F . , J. Am. Chem. Soc., 61, 157-61 (1939) . Campbell, J.A., Brit. J. Exp. Path., 15, 287-94 (1934). 9 . Campbell, J.A., Ibid, 20, 122-32 (1939)- 10. Cook, J.W., Nature, 14^, 335-8 (19^0). 11. Cook, J.W., Haslevood, G.A.D., Hevett, C.L., Hleger, I., Kennaway, X.L., and Mayneord, W.V., Am. J. Cancer ; 2g, 219-59 (1937). 12. Cook, J.V., and Kennaway, E.L., Ibid, ], 50-97 (1938). . 13. Cook, J.W., and Kennaway, E.L., Ibid, 39, 381-428, 521-82 (1940). 14. Oook, J.W., Hlager, I., Kennaway, E.L., and Mayneord, W.Y., Proc. Boy. soc., B i l l , 455-84 (1932). 15. Cramer, W . , and Stovell, R.E.,Cancer Research, 3. 668-81. (19^3) 16. Dobrovolskaya-Zavadskaya, N., Compt. rend. soc. biol., 129-, 1055-7 (1938). 17. Daalap, C.E., and Warren, S., Cancer Research, 3, 606-7 (1943). 18. ETns, E.E., J. Urol., 38, 212-15 (1937). ' 19. Fieaer, L.F., "Chemistry of Phenanthrone", Reinhold Publishing Company, N.Y., (1937). A P I 04664 1 Report Ho. M-1247 Bibliography (Continued) 20. Fieser, L.F., Am. J. Cancer, V, 37-124 (1938). 21. Fieser, L.F., and Campbell, W.P., J. Am. Cbem. Soc., 60, 1142-5 (1938) . 22. Fieser, L.F., and Fieser, M., "Organic Chemistry", pages 814-26, Heath and Co., Boston, Mass., 1944. 23. Gottschalk, R.G., Proc. Soc. Erp. Biol. Med., 0, 369-73 (1942). 24. Haddov, A.#, and Robinson, A.M., Proc. Roy. Soc., B127, 277-87 (1939) . 25. Hartwell, J.L., .S. Public Health Service, Nat. Inst. Health, Nat. Cancer Inst., 1941, "Survey of Compounds which Have Been Tested for Carcinogenic Activity", 371 pp. 26. Heller, I., J. Ind. Hyg., 12, 169-97 (1930). 27. Henry, S.A., Kennaway, N.M., and Kennavay, E.L., J. Hyg., 31, 125-37 (1931). 28. Hieger, I., Bioehem. J., 24, 5 0 5 - H (1930). 29. Hueper, W.C., J. Ind. Hyg., 6 , 255-79 (1934). 30. Kennavay, I.L., Brit. Med. J., 1925, H 1-4. 31. Kemaway, E.L., Biocham. J., 24, 497-504 (1930). 32. Kennaway, E.L., and Hieger, I., Brit. Med. J . , 1930, No. 3622, 1044-6. ' . - 33- Lavik, P.S., Moor, P.R., Rusoh, H.P., and Baumann, C.A., Cancer Research, 2, 189-92 (1942). 34. Linzbach, A.J., and Vedler, H.W., Arch. Path. Anat. (Virchow's), 307, 387-409 (1941). 35. Loeb. L., Alexander's "Colloid Chemistry", Vol. V, 995-1050 (1944), Reinhold Publishing Co., N.7. 36. Morton, A.A., Clapp, D.B., and Brand, C.F., Science, 82, 134 (1935). 37* Norimann, M., Z. B?ebaforach., 47, 288-302 (1938). API 04665 jeport Ho M-1247 *1 biioaraphy (Concluded) 38. Bobaon, J.M., andfBonaer, G.M., Nature, 1 U2 , 836 (1936) 39. Boffo, A.H., Prenaa Med. Argentina, 26, 721-38 (1939)* 1+0. Boffo, A.B., Bol. last. Med. Exp. Eatud. Cancer, lg, 741-56 (1939). l+l. Boffo, A.H., Ibid, 16, Ho. 52, 1-6 (1939). kZ. Boffo, A.H., ibid, 1J, 661-98 (19*0). 43. Boffo, A.*., and Boffo, A.E., Jr., ibid, 20, 143-87 (1943). Mi, Shear, M.J., Letter, J . , and Perrault, A., J. Hat. Cancer inat., 2 , 99-113 (1941). 45. Simpson, V.L., and Cramer, V., Cancer Beaearch, 3, 604-5 (1943). ' " 1+6. Stallybraaa, C.O., J. State Med., 4, 21+9-66 (192 6 ). 1+7. Stowell, B.E., and Craner, V., Cancer Beaearch, 2, 193-7 (1942). " 1+8. Tvort, C.C., and Pulton, J.D., J. Path. Boct., 33, 119-43 (1930) . 49. Tvort, C.C., M i L y t h , B., J. Hyg., 464-73 (1933). 50. Tvort, C.C., and Tuort, J.M., J. m i . Hyg., 13, 204-26 (1931) . 51. Tvort, C.C., and Tvort, J.M., J. Hyg., 22, 373-9 (1930). 52. Tvort, C.C., and Tvort, J.M., Ibid, 2, 130-49 (1935). 53- Tvort, C.C., and Tvort, J.M., Lancet, 1935, II, 1226-8. 54. Tvort, J.M., and Tvort, C.C., J. Hyg., 39, 161-9 (1939). 55. Woodhouae, D.L., J. Inat. Pet. Tech., 20, 1057-63 (1934). 0 For those vlahlng to acquire a more extenslre background In this field, a review by Pieaer20 la recommended aa a good starting point, followed by the original papers by Cook and co-workers. For a detailed tabulation of carcinogenic compounds Hartwell's book25 should be consulted. API 04666