The Whole Animal as an Assay System

Abstract

Advances in our ability to detect and measure environmental contaminants and their tissue products parallel our new emphasis on incipient functional impairment and long-range risk estimates as indices of toxic effects. Death and overt pathology no longer are credible criteria by which to set environmental standards. By turning to functional criteria, however, we provoke a new set of vexing problems, namely, how to define toxicity. Among the factors that blur such a definition are the following: How do we subsume adaptive and compensatory mechanisms? How do we take account of non-specific subjective complaints? How shall we incorporate the responses of susceptible populations such as the very young, the very old, and constitutional predispositions to adverse responses? Behavior exemplifies many of these problems of definition because it encompasses so many functions and because toxic end points are merely arbitrary stages in a continuum. It is an indispensable criterion, however, because it is the whole animal that responds--that dies, or grows weak or becomes irritable and depressed. The impact on its welfare is what defines an agent as a pollutant.