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MODELLING OF AGRICHEMICALS IN ENVIRONMENTAL COMPARTMENTS - CONCEPTS, PROBLEMS, AND SOLUTIONS
Citation:
Burns, L A. MODELLING OF AGRICHEMICALS IN ENVIRONMENTAL COMPARTMENTS - CONCEPTS, PROBLEMS, AND SOLUTIONS. Presented at XIVth International Plant Protection Congress, Jerusalem, Israel, July 25-30, 1999.
Description:
The potential of plant protection chemicals to migrate away from application sites and expose non-target biota is of continuing interest and concern to regulatory specialists, ecotoxicologists, agriculturalists, and natural resource managers. Regulatory decisions can wait upon neither extensive field experience nor upon complete scientific knowledge of the fate and transport behaviors of chemicals in every relevant physiographic setting. Thus, mathematical and computer-based models are a necessary and critically important part of the risk assessment armamentarium. The more reliable models are solidly based in physical principles (e.g., conservation of mass), algorithmic descriptions of chemical reaction mechanisms, and generalizations from extensive empirical studies of complex environmental behaviors (e.g., sorption to soils and sediments). Given this array of technologies, the completed risk assessment tools must be cast in a form useful to risk assessors, tested for their reliability and accuracy in predicting chemical fate and transport, and their performance quantified in relation to available field experience. In addition, the uncertainties in the predicted quantities must ultimately be characterized either qualitatively, by frequentist methods (e.g., Monte Carlo simulation), or by Bayesian statements of believability. This presentation will review the conceptual underpinnings of exposure analysis, discuss the practical problems encountered in the production of risk assessment tools and their application, enumerate some of the present and future solutions to these problems, and propose research likely to advance the development of more robust decision support systems for agrichemical safety evaluations.