This book is a specific Dictionary of Abbreviations & Acronyms provided in 4 main chapters and more than 250 sections, which are arranged according to the subject and in alphabetical order, of course, and includes the following: 1. Part One: General Consideration; 2. Part Two: Detailed Classification; 3. Part Three: Environmental Dictionary; 4. Part Four: Geographical Consideration. The main subject of the book is the thematic arrangement and classification of abbreviations in the field of toxicology and environmental sciences. This is the first book in terms of subject matter, categorization, comprehensiveness, variety, and breadth of content. It also includes Abbreviations and Acronyms commonly used in other European Languages/Countries (French, German, Spanish, Italian, Scottish, Russian) and some other regions like Canada, Australia, New Zealand, India, South Africa, Ireland, Japan, China, and United States and United Kingdom.