A unified approach to exposure assessment by computer models for degradation reactions and soil accumulation: The triazine herbicide example

A comprehensive approach to exposure assessment of chemicals must include m etabolites of the initial compounds. We present here an approach that combi nes a knowledge-based system for the prediction of degradation pathways wit h an analytical soil transport model. The performance of this combination o f systems is illustrated with an analysis of seven s-triazine herbicides an d their 35 degradation products. In a ranking procedure using the Hasse dia gram technique, the relationships between chemical structure and the hazard potential in a loam soil scenario is analyzed. Sequences of chemical struc tures with comparable and non-comparable hazard potentials are identified. (C) 1999 Elsevier Science Ltd. All rights reserved.