The term ecotoxicology is the branch of toxicology concerned with the study of toxic effects, caused by natural or synthetic pollutants, to the constituents of ecosystems, animal (including human), vegetable and microbial. This book discusses the ecotoxicological effects of pharmaceuticals in the environment; the effects of various ecotoxicants on nematodes; salinity threats to agricultural productivity; sorption and the ecological risk assessment of non-ionic organic contaminants; and the application of ecotoxicological tools in the assessment, monitoring of Brazilian waters; and others.