Types of Chemical Carcinogens

Activation-dependent Aromatic amine Polycyclic aromatic hydrocarbon 

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Another line of evidence that free radicals may be involved in chemical carcinogenesis is that antioxidants often act as anti-cancer compounds. Many types of chemical carcinogens, in a variety of organs and in many animal species, are protected against... 

Structural criteria are based on SAR analysis. Two basic approaches may be used firstly, structural analogies with established types of chemical carcinogens, and, secondly, considerations of molecular size, shape and symmetry, and of electron distribution and steric factors in and around functional groups, independently from any possible analogy with other compounds. Some of the structural criteria (see Appendix V of ref. 5 for details) are listed below ... 

Eor most of the toxic effects that might be exerted by a chemical substance, including at least certain types of genotoxic carcinogenicity, the dose-response curve is S-shaped as illustrated in Eigure 4.1 where the carcinogenic response is the mmor incidence. This means that no or only a few tumors occur at the lower dose levels, but the mmor incidence increases as the dose level increases, in many cases until a plateau is reached. 

Assuming that the toxic compounds are able to accumulate in the body, there are certain types of products which represent potential hazards. Three types of chemical compounds as well as the radiation itself have been tabbed for possible carcinogenicity (H2) (a) branching in fatty-acid carbon chains, (b) fatty acids with odd number of carbons, (c) oxidized sterols. 

Personnel protective equipment may be used in certain circumstances where exposure to airborne particulates contaminated with chemical carcinogens could occur. In those situations, personnel should be equipped with a complete clothing change, as well as respiratory protection selected on the basis of work performed, type of chemical used, and containment equipment. The respiratory protection may be a face mask, respirator [selected from those approved by the National Institute for Occupational Safety and Health (NIOSH)] (4, 5), or emergency breathing air system. In the latter case, a head hood or a complete protective suit may be used with a breathing air supply system. Figure 2. 

In general, four types of cabinets are used for work with research quantities of chemical carcinogens. These are the conventional fume hood a Class I biological safety cabinet a Class II (Type B) biological safety cabinet and a Class III closed glove box system (8). 

Chemical carcinogens are defined operationally by their ability to produce an Increase in tumor Incidence. Chemicals capable of eliciting a tumor response in experimental animals comprise a highly diverse collection of structural types of chemicals ( ). Considering this fact alone, it has seemed likely that the tumorigenic effects of carcinogens could be exerted by several mechanisms. Evidence of this is provided by observations that, al-... 

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