Carcinogens benzidine

Sellakumar et al. 1969 Stula et al. 1975, 1978). There is no conclusive evidence of carcinogenicity of 3,3 -dichlorobenzidine in hiunans (Gadian 1975 Gerarde and Gerarde 1974 MacIntyre 1975 Myslak et al. 1991 Ouellet-Hellstrom and Rench 1996) however, there is concern about occupationally exposed subjects because of 3,3 -dichlorobenzidine s structural similarity with the known human and animal carcinogen benzidine. However, imless a cohort exposed only to 3,3 -dichlorobenzidine is identified and adequate epidemiological studies on such a cohort are conducted, the question will remain unsolved. 

Ashby J, Mohammed R. 1988. UDS activity in the rat liver of the human carcinogens benzidine and 4-aminobiphenyl and the rodent carcinogens 3,3 -dichlorobenzidine and Direct Black 38. Mutagenesis 3(1) 69-71. 

Because of demonstrated potent carcinogenicity in multiple animal species, evidence of genotoxicity, and structural relationship to the known bladder carcinogen benzidine, DCB should be regarded as a probable human carcinogen and exposure by any route should be avoided. ... 

Azo dyes made from 47, and also their cleavage products from azo reduction, are appreciably less genotoxic than the corresponding benzidine-based dyes. An example is the mutagenic (and carcinogenic) benzidine-based dye Direct Violet 43 (48) and its corresponding isosteric analog (49), in which the benzidine moiety is replaced with 47. Other examples are available [84]. 

Figure 4.69 Metabolism of the carcinogen benzidine showing oxidation and acetylation. Both routes of acetylation can give rise to a reactive nitrenium ion and DNA adducts. Abbreviation. NAT, N-acetyltransferase.

In contrast to some naturally occurring dyes like indigo or kermes, which must be vatted or mordanted to be applied in textile dyeing, direct or substantive dyes can be used on cellulosic fibers directly . Their use is widespread because of their easy handling. Today, direct dyes still account for ca. 10% of the world textile dye consumption. For use on paper, see Section 5.3. Recent research on direct dyes concentrated on the replacement of possibly carcinogenic benzidine dyes [44],... 

While the development of direct dyes was essentially completed in the 1930s, it was reactivated in the 1960s and 1970s, when it was found that benzidine, an important direct dye intermediate at the time, is carcinogenic. Benzidine dyes are used for some yellows and reds and mostly for black. In view of the ensuing concern, the leading dye producers withdrew benzidine-based dyes preemptively to protect their workers, dyers, and consumers. Studies to find alternative dyes were undertaken, and this work led eventually to many of today s most important black dyes for leather, e.g,C.I. DirectBlack 168, 30410 [85631-88-5] (16). 

Benzidine and cancer Industrial workers exposed to benzidine developed increased risk of bladder cancer. The U.S. EPA has classihed benzidine as group A, meaning a hnman carcinogen. Benzidine is a well known carcinogen in animals and the lARC has classified it as group 1 meaning a hnman carcinogen. ... 

The highly carcinogenic benzidine, 4,4/-diaminobiphenyl (31b), was formerly made by reduction of nitrobenzene to hydrazobenzene, with subsequent rearrangement. Similar methods are used to prepare substituted benzidines that are believed to be non-mutagenic and non-carcinogenic. The 3,3 -dichloro derivative is a suspected carcinogen. 

Fig. 16B) [56]. Another class of azo-containing compounds that readily undergo reduction either by mammals or intestinal bacteria are the azo dyes, such as Congo red, which is metabolized to the carcinogen benzidine (Fig. 16B) [57]. 

MBOCA is suspected of being a human carcinogen because its chemical structure is similar to a known human bladder carcinogen, benzidine, and to that of a potent animal carcinogen,... 

Benzidine Dyes. The well-documented metabolic breakdown of benzidine dyes to the starting material and human carcinogen, benzidine, is today recognized by the dyestuff industries in both Europe and the United States. Because of this, a voluntary withdrawal of this type of dyestuff was enacted several years ago in the US, and more recently, in Europe. Today, however, it is still possible to import benzidine dyes into the US from Mexico and India, and regulatory action appears to be necessary even by such a simple stratagem as deleting the dyes in question from the TSCA Inventory. 

Carcinogen May cause cancer lA, IB Danger Known or presumed human carcinogen Benzidine, 2-naphthylamine, dimethylni- trosamine, bis(chloromethyl) ether, ethylenimine, nickel carbonyl, /3-propiolactone, vinyl chloride... 

Methylenedianiline and 4,4 -methylene-bis-chloroaniline are two widely used aromatic amines employed in the manufacture of polyurethane foams, epoxy resins and as a curing agent in rubber manufacture. These two chemicals have been shown to be carcinogenic and mutagenic in a number of animal species, and they are structurally similar to the known human bladder carcinogen benzidine (McQueen et al. 1981 Lamb et al. 1986). Both chemicals have been detected in the urine of factory workers (Cocker et al. 1988), and Hotchkiss et al. (1993) reported substantial absorption through human skin in vitro. 

Both 1-naphthylamine (a-naphthylamine) and 2-naphthylamine (P-naphlliyl-amine) are proven human bladder carcinogens. In addition to being a proven human carcinogen, benzidine, 4,4 -diaminobiphenyl, is highly toxic and has systemic effects that include blood hemolysis, bone marrow depression, and kidney and liver damage. It can be taken into the body orally, by inhalation into the lungs, and by skin sorption. 

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