Carcinogens, table

Etliylene production involves liigh temperatures (1500°F) in tlie pyrolysis section and cryogenic temperatures in tlie purification section. The feedstocks, products, and by-products of pyrolysis are flaimnable and pose severe fire liazards. Benzene, wliich is produced in small amounts as a byproduct, is a known carcinogen. Table 21.7.1 summarizes some of the properties of etliane (feedstock) and tlie product gases. Figure 21.7.1 shows a simplified schematic diagram of the pyrolysis and waste heat recovery section on an etliylene plant. 

About 50 percent of chemicals, both natural and synthetic, that have been tested in standard, high-dose, animal cancer tests are rodent carcinogens (Table l).2 What explains the high per-... 

The numerical value shows the threshold limit value (TLV), which is defined as the maximum permissible vapor concentration that the average person can be exposed for 8 h per day, 5 days per week without harm, in ppm (cm3 of solvent vapor per 1 m3 of air). The mark T shows the solvent has been listed in Title III of the Clean Air Act Amendments of 1990 as a hazardous air pollutant (HAP). C shows that the solvent is or is suspected to be carcinogenic (Table 20.1.3 of Wy-pych, G. (Ed.) Handbook of Solvents, ChemTec Publishing, Toronto, 2001). 

Carcinogen exposure is largely due to lifestyle, such as cigarette smoking, but occupation is an important source of exposure to carcinogens. Table 4.4 lists some occupational chemical hazards and the cancers associated with them. 

There is little in the literature relative to vitamin A and colon cancer in human populations. Experimental animal studies, however, strongly suggest that vitamin A deficiency may have a role in this type of cancer. We have shown that a deficiency of vitamin A increased DMH-induced tumors and shortened the lag time for induction, compared to normally supplemented controls (72). More recently (73) we have confirmed a protective role for vitamin A in colon carcinogenesis (Table XVII). Furthermore, we have shown (74) that vitamin A deficiency can result in colon tumors in rats given aflatoxin (AFB ) which is normally a liver carcinogen (Table XVIII). The colon tumors associated with the hepatocarcinogen AFB.. appear to be a result of differences in metabolism and binding of AFB or its metabolite ) to colon DNA under conditions of vitamin A deficiency (75). 

CHAPTERS HAZARD AND RISK ASSESSMENT OF CHEMICAL CARCINOGENICITY TABLE 3.4. Induction of Liver Carcinomas in BDII Rats by DENA... 

CHAPTER 20 (Q)SAR ANALYSIS OF GENOTOXIC AND NONGENOTOXIC CARCINOGENS TABLE 20.2. Mechanism-based SAR Analysis of Fibers and Particles... 

The carcinogenicity of genotoxic procarcinogens can be increased or decreased by modification of the enzyme systems involved in their biotransformation (18-21). Several pesticidal compounds known to Induce drug metabolizing enzymes of the liver have been reported to influence the outcome of carcinogenic effect of known carcinogens (Table II). 

For the methylbenz [a] anthracenes (1), careful study by a number of workers has yielded experimental indices which, within the limits of biological testing, are consistent and cover the whole range of carcinogenicity (Table 4.1). Comparison of these indices with those for active dimethylene- and polymethyl-substituted benz [a] anthracenes (Table 4.2) illustrates the effect of substitution... 

Among all mycotoxins, aflatoxins are the most toxic, widespread, and the strongest natural carcinogens (Table 11.2). The International Agency for Research on Cancer (lARC) has defined aflatoxin B1 (AFBl) as a carcinogen [11]. 

The analysis of nitroaromatics and their metabolites is of particular importance in the assessment of military waste. Fourteen by-products and degradation products of 2,4,6-TNT (trinitrotoluene) alone are definitely classified or suspected as carcinogens (Table 4.56). 

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