Carcinogen complete

THPOH—Ammonia—Tris Finish. By far the most effective finish for polyester—cotton textiles was a system based on the THPOH—NH treatment of the cotton component either foUowed or preceded by the appUcation of Tris finish to the polyester component. This combined treatment appeared to be effective on almost any polyester—cotton blend. A large amount of fabric treated in this way was sold throughout the United States and much of the rest of the world. Shortly after the introduction of Tris finishing, Tris was found to be a carcinogen. Most of the Tris treated production was in children s sleepwear, and this created a situation in which almost aU chemical fire-retardant-treated textiles were unfairly condemned as dangerous. Manufacturers mshed to replace chemically treated textiles with products produced from inherently flame-resistant fibers. Nowhere was the impact more severe than in the children s sleepwear market. New, safer materials have been introduced to replace Tris. Thus far none has been as completely effective. 

The identification of Tris as a potential carcinogen dealt a resounding blow to the flame-retardant finishing industry. From 1977 to 1984, several principal supphers of flame-retardant chemicals either reduced the size of their operations or abandoned the market completely. However, Albright and Wilson Corp. (UK) continues to produce THPC—urea precondensate and market it worldwide, and Westex Corp. (Chicago) continues to apply precondensate—NH finish to millions of yards of goods for various end uses. American Cyanamid reentered the market with a precondensate-type flame retardant based on THPS. 

L-Tyrosine metabohsm and catecholamine biosynthesis occur largely in the brain, central nervous tissue, and endocrine system, which have large pools of L-ascorbic acid (128). Catecholamine, a neurotransmitter, is the precursor in the formation of dopamine, which is converted to noradrenaline and adrenaline. The precise role of ascorbic acid has not been completely understood. Ascorbic acid has important biochemical functions with various hydroxylase enzymes in steroid, dmg, andhpid metabohsm. The cytochrome P-450 oxidase catalyzes the conversion of cholesterol to bUe acids and the detoxification process of aromatic dmgs and other xenobiotics, eg, carcinogens, poUutants, and pesticides, in the body (129). The effects of L-ascorbic acid on histamine metabohsm related to scurvy and anaphylactic shock have been investigated (130). Another ceUular reaction involving ascorbic acid is the conversion of folate to tetrahydrofolate. Ascorbic acid has many biochemical functions which affect the immune system of the body (131). 

Indieates tliat tlie RQ is subjeet to change when tlie assessment of potential carcinogenicity and/or otlicr toxicity is completed. 

Alcohol sulfates and alcohol ether sulfates were examined many years ago for their carcinogenic, mutagenic, and teratogenic properties. A complete revision of these subjects was carried out by Oba [382]. 

Carcinogenic agents include chemicals in the environment, such as aniline and benzene, which are associated with the development of bladder cancer and leukemia, respectively. Environmental factors, such as excessive sun exposure, also may result in cancer. Viruses, including the human papilloma virus and hepatitis B, maybe associated with the development of cancer. Some of the chemotherapy agents cause secondary cancers after therapy has been completed. Numerous factors may contribute to the development of cancer. 

In contrast to BP, benzo(e)pyrene (BeP) is generally considered to be inactive as a complete carcinogen (38). The only vicinal diin Polycyclic Hydrocarbons and Carcinogenesis Harvey, R. ... 

Chrysene is a weak tumor initiator and is inactive as a complete carcinogen (38). The 1,2-dihydrodiol is more active as a mutagen than the 3,4- or the 5,6-dihydrodiols. The biological data support the hypothesis that the principal active metabolite of chrysene is the bay region anti-1,2-diol-3,4-epoxide (58). 

However, such intercalation involves the insertion of a flat molecule, with a ir-electron system, between the ir-electron systems of the bases of DNA. Therefore a buckled molecule and/or a methyl group will not fit well in such an intercalation mode. Thus, since the buckled molecules (with a methyl group in the bay region) are more carcinogenic, we concluded that complete intercalation of the hydrocarbon between the bases of DNA is not a likely mechanism for carcinogenicity, since the less planar molecules are more active in terms of carcinogenic activity. However, as we shall show later, it is possible that the planar portion of the PAH may lie between the bases of DNA in a semi-intercalation mode the methyl groups, if present, probably do not take part in this semi-intercalation. 

Thus complete intercalation of the aromatic PAH between the bases of DNA, in the manner described above for flat molecule such as proflavine, did not seem to be a likely mechanism for the carcinogenic action of these compounds. Since alkylation and intercalation are not simultaneously possible for steric reasons, and since one molecule is wedge-shaped and the other is flatter, it was considered more likely that the action of these compounds arose from their alkylating ability they could alkylate a base of DNA and then, since the bulky aromatic hydrophobic group would possibly not remain protruding into the hydrophilic environment, it is possible that the aromatic PAH group could then lie in one of the grooves of DNA. 

Studies on the comparative abilities (13) of B[a]P metabolites to bind to DNA in microsomal systems showed that the 7,8-dihydrodiol was the most efficient. This led to the proposal (69) that dihydrodiol epoxides were the ultimate carcinogenic metabolites. Chemical synthesis of all possible isomers (70.71) has allowed complete structural identification of the adducts (72-74). 

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