Carcinogens benzo pyrene

It shows DNA damaged by the environmental chemical carcinogen benzo[ ]pyrene in the active site of the human DNA bypass polymerase k. 

The use of subcritical water at 275°C was successful in removing PAHs with two to six rings (including the carcinogenic benzo[a]pyrene) from soil at a contaminated site, and the wastewater that was produced appeared to be suitable for further exploitation (Lagadec et al. 2000). 

Lu, P.-Y., R.L. Metcalf, N. Plummer, and D. Mandrel. 1977. The environmental fate of three carcinogens benzo-(a)-pyrene, benzidine, and vinyl chloride evaluated in laboratory model ecosystems. Arch. Environ. Contam. Toxicol. 6 129-142. 

Benzo[/ ]pyrene is designated an A2-sus-pected human carcinogen by ACGIH and has no assigned threshold limit value. 

In skin-painting studies in mice, catechol increased the carcinogenic effects of benzo[< ]pyrene (B(skin tumors was compared with that obtained from groups treated with B([Pg.129]

Clearly, a sound evaluation of the total mutagenic/carcinogenic potencies of a complex mixture of POM emissions (e.g., diesel exhaust) should include not only the PEFs of the primary particle- and vapor-phase PAHs and PACs but also those of the mutagens formed in atmospheric reactions of precursor PAHs (see, for example, Arey et al. (1992), Lewtas (1993b), Atkinson and Arey (1994), Nielsen et al. (1996), Arey (1998a), and Section F). For examples of such formal scientific health risk assessments prepared by the State of California Air Resources Board and Office of Environmental Health Hazard Assessment, see Benzo[ ]pyrene as a Toxic Air Contaminant (CARB, 1994) and Identification of Diesel Exhaust as a Toxic Air Contaminant (CARB, 1998). 

Kozack R, Seo KY, Jelinsky SA, et al. Toward an understanding of the role of DNA adduct conformation in defining mutagenic mechanism based on studies of the major adduct (formed at N2-dG) of the potent environmental carcinogen benzo[a]pyrene. Mutat Res 2000 450(1-2) 41-59. 

Baturay. N. Kennedy, A.R. (1986) Pyrene acts as a cocarcinogen with the carcinogens benzo[o]pyrene, P-propiolactone and radiation in the induction of malignant transformation in cultured mouse fibroblasts soybean extract containing the Bowman-Birk inhibitor acts as an anticarcinogen. Cell Biol. Toxicol., 2, 21-32... 

Activation of the promutagen/carcinogen benzo[a]pyrene by reactive oxygen species/liver P-450 (S-9) fraction and reaction of benzo[a]pyrene epoxydiol with DNA. GSH = glutathione, DNA = deoxyribonucleic acids, X = a general nucleophile not specifically explicated. 

Lindquist, B. Warshawsky, D. (1985b). Stereospecificity in algal oxidation of the carcinogen benzo[a]pyrene. Experientia, 41, 767-9-... 

The oxidation of naphthalene was one of the earliest examples of an epoxide as an intermediate in aromatic hydroxylation. As shown in Figure 7.3, the epoxide can rearrange nonenzymatically to yield predominantly 1-naphthol, or interact with the enzyme epoxide hydrolase to yield the dihydrodiol, or interact with glutathione S-transferase to yield the glutathione conjugate, which is ultimately metabolized to a mercapturic acid. These reactions are also of importance in the metabolism of other xenobiotics that contain an aromatic nucleus, such as the insecticide carbaryl and the carcinogen benzo(a)pyrene. 

Formation of a dihydrodiol by hydration of epoxide groups can be an important detoxication process in that the product is often much less reactive to potential receptors than is the epoxide. However, this is not invariably the case because some dihydrodiols may undergo further epoxidation to form even more reactive metabolites. As shown in Figure 7.3, this can happen with benzo(a)pyrene 7,8-epoxide, which becomes oxidized to carcinogenic benzo(a)pyrene 7,8-diol-9,10-epoxide. The parent polycyclic aromatic hydrocarbon benzo(a)pyrene is classified as a procarcinogen, or precarcinogen, in that metabolic action is required to convert it to a species, in this case benzo(a)pyrene 7,8-diol-9,10-epoxide, which is carcinogenic as such. 

Figure 7.3 Epoxidation and hydroxylation of benzo(a)pyrene (left) to form carcinogenic benzo(a)pyrene 7,8-...

Syn dihydrodiol epoxide adducts formed in mouse skin treated with benzo[ ]pyrene constitute only about 12% of the total binding (36) and dihydrodiol epoxide deoxyadenosine adducts account for even less (2 to 3%) of the total (37,38). DMBA is approximately 20 times more potent a carcinogen than BP and this difference cannot be explained by the 2- to 4-fold difference in overall binding to DNA by these two carcinogens in mouse skin (35). Thus, these more subtle differences in DNA reaction products, i.e. the difference in reaction of syn-stereoisomer with DNA or in the modification of deoxyadenosine residues, might account for the greater tumor-initiating potential of DMBA. 

Figure 24.11. Metabolic activation of benzo[a]pyrene to the ultimate carcinogenic species. Benzo[a]pyrene is metabolized by cytochromes P-450 and epoxide hydrolase to form the ultimate carcinogen, (+)benzo[a]pyrene-7,8-diol-9,10 epoxide-2. (Adapted from Conney, A. H. Cancer Res. 42, 4875,1982.)...

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