BEYOND SCREENING - PROBLEMS AND PROSPECTS FOR RISK CHARACTERIZATION OF ENDOCRINE DISRUPTORS

Over time, the NAS's original concept of ''risk characterization'' has broadened to include not just explication of the risk inferences them selves, but a forthright discussion of their dependence on the many le ss-than-certain elements of the inferential process. Ideally, such cha racterization communicates the span of possible conclusions that emerg e hom alternative reasonable interpretations of the information at han d, together with considered judgment regarding the likelihood that eac h interpretation provides a good representation of the actual situatio n. Uncertainties regarding the magnitudes of parameters in the various equations used in quantitative risk assessment are increasingly chara cterized using statistical tools for analysis and propagation of varia nce through the calculations. Of potentially greater concern, however, is ''model uncertainty''-the more fundamental uncertainty regarding t he soundness of our conception of what biological phenomena are operat ing, how they interact, and how they can be represented in quantitativ e models. This is particularly true for assessment of potential endocr ine disrupters, since much fundamental information is lacking and unan swered questions exist about the consequences and interpretation of em pirically observable effects. An approach is to define a series of alt ernative models, each embodying a different conception, and using expe rt scientific judgment to weigh the individual results. (C) 1997 Acade mic Press.