The field of science that focuses on the harmful effects of diverse physical and biological agents on living organisms is called environmental toxicology. There are many sources that can lead to the presence of environmental toxicants. These include pesticides, organic and inorganic pollutants. Other sources comprises of heavy metals like arsenic lead, and cyanobacteria and cyanotoxins. Ecotoxicology is the branch of environmental toxicology which studies harmful effects of toxins on ecosystem and population. Aquatic toxicology is the multidisciplinary field that studies toxic effects of anthropogenic and natural activities on aquatic organisms and their ecosystem. This book attempts to understand the multiple branches that fall under the discipline of environmental toxicology and how such concepts have practical applications. The objective is to give a general view of the different areas of this field. This book, with its detailed analyzes and data, will prove immensely beneficial to professionals and students involved in this area at various levels.