Introduction

Abstract

A principal goal of pesticide science is to be able to predict the environmental impact of a pesticide before it is released into the environment. To save expense and time, we would like to be able to make such a prediction for each pesticide with as few laboratory experiments on the pesticide as possible, and even fewer field experiments. Environmental processes, however, are enormously complex and sometimes (apparently) random. The sites of most interest—agricultural fields, forests, lakes, streams, etc.—are subtle living ecosystems that are incompletely understood and subject to great variability in space and time. The very diversity and intricacy that are indicators of the health of such ecosystems make a difficult task of even defining what constitutes a significant impact on such systems.