Classical Viewpoint for Classifying Toxicological Effects

Techniques have been derived to evaluate effects at each step, from the introduction of a xenobiotic to the biosphere to the final series of effects. These techniques are not uniform for each class of toxicant, and mixtures are even more difficult to evaluate. Given this background, however, it is possible to outline the levels of biological interaction with a xenobiotic as follows  

Chemical/physical-chemical characteristics Bioaccumulation/biotransformation/biodegradation 

The three functions of environmental toxicology. Only three basic functions need to be described after the introduction of a xenobiotic into the environment. The first describes the fate and distribution of the material in the biosphere and the organism after the initial release to the environment [f(f)]. The second function describes the interaction of the material with the site of action [f(s)]. The third function describes the impact of this molecular interaction upon the function of an ecosystem [f(e)]. 

Site of action Biochemical monitoring Physiological and behavioral effects Population parameters Community parameters Ecosystem effects 

The interaction of the atoms and electrons within a specific molecule determines the impact of the compound at the molecular level. The contribution of the physical-chemical characteristics of a compound to the observed toxicity is called quantitative structure-activity relationship (QSAR). QSAR has the potential of enabling environmental toxicologists to predict the environmental consequences of toxicants using only structure as a guide. The response of a chemical to ultraviolet radiation and its reactivity with the abiotic constituents of the environment determine the fate of a compound. 

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