Carcinogen promotors

Skin studies have indicated that phenol can act as a promotor following treatment with a polyaromatic hydrocarbon (Boutwell and Bosch 1959 Salaman and Glendenning 1957). These studies are limited because phenol was administered in benzene (Boutwell and Bosch 1959) or acetone (Salaman and Glendenning 1957). An additional dermal carcinogenicity study in which phenol is administered in water is necessary to predict the carcinogenicity of phenol following dermal exposure. 

Most substances classified as epigenetic carcinogens are promoters that act after initiation. Manifestations of promotion include increased numbers of tumor cells and decreased length of time for tumors to develop (shortened latency period). Promoters do not initiate cancer, are not electrophilic, and do not bind with DNA. The classic example of a promotor is a substance known chemically as decanoyl phorbol acetate or phorbol myristate acetate, a substance extracted from croton oil. 

Hexametapol is difficult to purify and dry [3] and it is a SUSPECTED CARCINOGEN, but it is a particularly good promotor of electron transfer reactions. 

It is now established that dioxins are strong immunotoxicants, teratogens, carcinogens (as promotors), and make chloracne (Kohn et al., 1996 Melnick et al., 1996 Portier et al., 1996). Note, as already mentioned, that the toxicities for different animals are very different. Humans may be less sensitive than many other mammals. Table 10.5 shows LD50 values of 2,3,7,8-TCDD for various animals. 

It is also possible that the skin irritant effects of Stoddard solvent could have contributed to the promotion of effects initiated by other components of the mixture. The alkylbenzenes present in Stoddard solvent are not believed to be carcinogenic, based upon negative or weakly positive genotoxicity test results (Andrews and Snyder 1991). However, further animal testing is needed to confirm a lack of carcinogenicity. A dermal study in mice showed that dodecane was a tumor promotor (Sice 1966). Benzo[a]pyrene and benzo[a]anthracene were reported to be 1,000 times more potent in producing tumors when dodecane was used as a diluent than when it was not used (Bingham and Falk 1969). 

INITIATOR A CARCINOGEN whose activity has been potentiated by a PROMOTOR. 

PROMOTOR A substance, itself not a CARCINOGEN, which has the property of being able to increase enormously the carcinogenic activity of a weak carcinogen, or increase the efficiency of extremely small doses of strong carcinogens. Also called a cocarcinogen. 

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