CECs are not regulated substances, and therefore not considered in national and international monitoring programs, even though they may have a potential impact on the environment due to their continuous input, relative persistence, and/or toxicity. CECs are relevant not only in continental and coastal areas close to their main sources, but also in the open sea, because some of them are likely to be transported long distances through air deposition or absorbed into particulate material. The persistence of many degradable substances in the marine environment increases when they are absorbed into particulate material/sediments and/or when they are subjected to anaerobic conditions that slow down the degradation kinetic of many contaminants. Bioaccumulation of several CECs has been confirmed in different coastal organisms; however, in general, the information available (species and trophic levels considered) is very limited because most studies are mainly focused on specific coastal areas. This book offers useful information about not regulated contaminants that are not considered in international monitoring programs but have potential impacts in coastal and open-sea areas. Therefore reading the book will allow them to improve their view about the real impact of current-use contaminants in the marine environment.