Currently, ecological risk assessments for pesticides use largely deterministic methods, yet there is a growing trend from industries and governments toward more quantifiable results using probabilistic methods. Identifying which methods are most appropriate for pesticide assessment, this book explores their suitability as a common protocol for general use. The authors discuss classical and Bayesian approaches, various types of Monte Carlo analysis, first order error analysis, probability bounds analysis, interval analysis, and fuzzy mathematics. They then examine how these methods can be used in assessments for other environmental contaminants.