The primary purpose of this book is to provide an update on research in the field of environmental impact of agricultural chemicals. As society becomes more concerned with non-target effects of pesticides and their residues in the environment, it is imperative that researchers develop a deeper and broader understanding of the types of effects, the quantities of the compounds that are biologically available, and the probability of serious impacts. Risk assessment can utilize information about the effects and the quantities to develop assessments of the likelihood for a given chemical, used in a specific place and time, to have deleterious effects on various species or ecological associations in the ecosystem.