TESTING FOIL LONG-TEILM TOXICITY Table XII Cocarcinogenic Effect of Phorbol Esters a 835 Time to Papilloma Primary Papilloma Incidence Trcatmentb Secondary Treatment (Days) (%) DMBA None 266 15 Croton flow dose c 222 40 DMBA ester A•high dose d 51 95 DMBA Croton Ilow dose c 104 45 ester C[high dose d 51 100 a Data from Van Duuren and Orris (43). •, A single application of 300 /•g of 7,12-dimethylbenz(a)anthracene was used in each case. The animals were Swiss Millerton female mice. c The croton ester was applied at a dose of 0.5/•g twice weekly beginning 14 days after pri- mary treatment. a The material was applied to the skin at a dose of 5.0/•g 3 times weekly beginning 14 days after primary treatment. comes from the report of Van Duuren and Orris (43). The esters de- creased the time for tumor formation but increased markedly the tumor incidence (Table XII). From this brief survey it is concluded that many factors are capable of influencing the actual response of an animal system to a carcinogen. Some of these factors cancel the effects of each other, while in other cases the net effect may be an enhancement of the response. COMPOUNDS UNDER TEST Following this survey ot• some of the possible influences on carcino- genic response, the types of compounds now under test in the NGI bio- assay program are next considered. A number of these compounds are being investigated because (a) they are known to be commercially im- portant, and (b) adequate data on these materials are not available in the scientific literature. Many of these compounds are being administered in the feed but not because they are necessarily food additives. However, this route simulates entry of dusts into the system. They include dyestuff intermediates, mostly aromatic amines, some ot• which are employed in cosmetic formulations (hair dyes), while others are industrial intermediates for dyes or polymers. Also being tested are pesticides, polymers, and intermediates to prepare them chemotherapeu- tic agents, perfumery and flavoring agents, tobacco smoke components, and possible food contaminants.

836 JOURNAL OF THE SOCIETY OF COSME•I'IC CHEMISTS CONCLUSION In summary, a survey has been made of the methods generally em- ployed in testing compounds for long-term toxicity or carcinogenicity. The factors which should be kept in mind when selecting animal test systems and the influence these factors can have on the outcome have been mentioned. Under current NCI bioassay programs, many com- pounds of environmental importance are being tested for possible car- cinogenicity. It is NCI policy to encourage publication of the results in the scientific journals so that the data are available for all. (Received May 26, 1971) REFERENCES (1) Boutwell, R. K., Tests for chemical carcinogens and their use in the evaluation of safety of cosmetics, Toxicol. Appl. Pharmacol., Suppl., 3, 113 (1969). (2) Sternberg, T. H., Newcomer, V. D., Cainan, C. C., Rostenberg, A., It., and Rothman, S., The Evaluation o[ Therapeutic Agents and Cosmetics, McGraw-Hill, New York, 1964. (3) Weisburger, J. H., and Weisburger, E. K., Tests [or Chemical Carcinogens, in Busch, H., Methods in Cancer Research, Vol. 1, Academic Press, New York, 1967, p. 370. (4) Clayson, D. B., Chemkal Carcinogenesis, Little, Brown & Co., Boston, 1962. (5) Arcos, ]. C., Argus, M. F., and Wolf, G., Chemical Induction o[ Cancer, Vol. 1, Academic Press, New York, 1968. (6) Appraisal o[ the Sa[ety o/ Chemicals in Foods, Drugs, and Cosmetics, Assn. of Food & Drug Officials ,of the United States, Austin, Texas, 1959. (7) Boutwell, R. K., Some biological aspects of skin carcinogenesis, Progr. Exp. Tumor Res., 4, 207 (1964). (8) Toth, B., A critical revicw of experiments in chemical carcinogenesis using newborn animals, Cancer Res., 28, 727 (1968). (9) Della Porta, G., and Terracini, B., Chemical carcinogenesis in infant animals, Progr. Exp. Tumor Res., 11, 334 (1969). (10) Mirvish, S.S., Cividalli, G., and Berenblum, I., Slow elimination o,f urethan in rela- tion to its high carcinogenicity in newborn mice, Proc. Soc. Exp. Biol. Med., 116, 265 (1964). (1 I) Weisburger, J. H., Klein, M., Weisburger, E. K., Glass, R. M., Woodard, G., and Cro- nin, M. T. I., Comparison of the effect of the carcinogen N-hydroxy-N-2-fiuorenylacet- amide in infant and weanling rats, J. Nat. Cancer Inst., 45, 29 (1970). (12) Bates, R. R., Sex hormones and skin tumorigensis. 1. Effect of the estrous cyde and castration on tumorigenesis by 7,12-dimethylbenz(a)anthracene, Ibid., 41, 559 (1968). (13) Bock, F. G., Early effects of hydrocarbons on mammalian skin, Progr. Exp. Tumor Res., 4, 126 (1964). (14) Morris, H. P., and Firminger, H. I., Influence of sex and sex hormones on development of heptatomas and other hepatic lesions in strain AXC rats ingesting 2-diacetylamino- fiuorene, J. Nat. Cancer Inst., 16, 927 (1956). (1.5) Hartwell, J. L., Su•ey o[ Compounds Which Have Been Tested for Carcinogenic Ac- tivity, 2nd ed., Public Health Service Publication No. 149, U. $. Government Printing Office, Washington, 1951.