An international group of 32 scientists has critically reviewed the scientific literature on exposure and effects of environmental contaminants in wild mammals. The underlying theme of this text is encompassed by the following four questions: What exactly do we know about environmental contaminants in mammals? What are the commonalities and differences between mammal orders/species in the effects that contaminants have? How and to what degree of accuracy can we predict the adverse effects of environmental contaminants on mammalian wildlife? How significant are contaminant insults compared with other density-independent and -dependent factors such as habitat loss, climatic factors and disease? The book is organized three topical sections including introductory chapters that provide a background on environmental contaminants and the mammalian orders, eight taxonomic chapters discussing all aspects of the exposure to and effects of contaminants in mammalian orders, and four thematic chapters that review and discuss generic issues including biomarkers, prediction and extrapolation of exposure and effects, hazard and risk assessment, and the relative significance of contaminants on mammals compared with other commonly encountered stressors. A final a summary chapter identifies phylogenetic trends, critical data gaps, and overarching research needs. Although the absolute number of toxicological studies in domesticated and wild mammals eclipses that wildlife species, a detailed examination of our knowledge base reveals that information for 'wild' birds is actually greater than that for 'wild' mammals. Of the various mammalian taxa, ecotoxicological data is most noticeably lacking for marsupials and monotremes. In contrast, rodents (comprising 43% of all mammal species) have been studied extensively, despite evidence of their tolerance to some organochlorine compounds, rodenticides, and even radionuclides. Mammalian species at greatest risk of exposure include those that consume a high percentage of their body weight on a daily basis. Aquatic mammals tend to bioaccumulate tremendous burdens of lipophilic contaminants, although storage in their fat depots may actually limit toxicity. Carnivores appear to be more sensitive to adverse effects of environmental contaminants than herbivores. Remarkably few of the thousands of compounds manufactured worldwide have been toxicologically evaluated in wild mammals, and concentrations of even fewer have been monitored in tissues.