Carcinogenic effect, prediction

One may question this reasoning on the basis that data from two poor predictors may not be significantly better than data from a single species. It is also reasonable to expect that the ability of one rodent species to predict a carcinogenic effect in a second rodent species should be at least equal to, if not better than, its ability to predict carcinogenicity in humans. The concordance... 

The rat liver foci assay is a short-term in vivo test to predict carcinogenic potential of a chemical. In this assay, 1,2-dibromoethane has both initiating and promoting activity, which correlates well with its carcinogenic effects in animals. 

The treatment of animals with growth-promoting hormones is a common practice in conventional agriculture outside of the EU. The effects of this practice are still not predictable in an entirely reliable way with respect to the toxic and carcinogenic effects of their residuals on humans (Collins et al. 1989). Although their use was banned in the EU several years ago, satisfactory controlling mechanisms have not been established. 

In an attempt to determine whether the carcinogenicity observed in animal studies was predictive for humans, the mortality experience of ammunitions workers with opportunity for substantial DNT exposure was examined. No evidence of carcinogenic effect was found, but an unsuspected excess of ischemic heart disease was noted. Additional analyses showed evidence of a 15 -year latency period and suggested a relationship with duration and intensity of exposure. ... 

Chemicals differ widely also in molecular structure, biological activity, and mode of action. Because the relationships among these properties are as yet ill defined and poorly understood, the carcinogenic effects of one chemical cannot be confidently predicted from those of another. 

It is possible to use this OH° concentration to predict k for the oxidation of other compounds under the same conditions. Von Gunten et al. (1995) calculated the actual concentration of OH° using this general and easy way for the ozonation of surface water at neutral pH in a two-stage pilot plant. Atrazine was used as the model compound, ozone decay was assumed to be of first order and the reactors completely mixed. Based on this model they were able to precisely predict the formation of bromate (Br03 ) by oxidation of bromide (Br ) for a full-scale water treatment plant. Bromate is a disinfection byproduct (DBP) of the ozonation of bromide-containing waters, and of concern because of its carcinogenic effects in animal experiments (see also Chapter A 3). 

Kitchin KT (1999) Carcinogenicity Testing, Predicting, and Interpreting Chemical Effects. New York Dekker. 

Oncologic This model is used to predict carcinogenic potential in humans. Other non-carcinogenic effects (e.g., acute toxicity, developmental toxicity) cannot be modeled at the present time and, therefore, conventional SAR and read-across methods must be used to predict these endpoints. 

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