ABSTRACT
The organic pollutants discussed in this book are examples of xenobiotics. A xenobiotic is here defined as a compound that is foreign to a particular organism. This means that it does not play a part in normal biochemistry. By this definition, a chemical that is normal to one organism may be foreign to another. Thus xenobiotics may be naturally occurring as well as manmade (anthropogenic) and must have existed since early in the evolutionary history of this planet. From an evolutionary point of view, the role of naturally occurring xenobiotics as chemical warfare agents is of considerable interest. For example, there is much evidence for the evolution of detoxication mechanisms by animals to give them protection against toxic xenobiotics produced by plants. Nearly all the organic pollutants referred to in Chapter 1 are man-made xenobiotics; they do not occur in nature. It is, however, important to remember that naturally occurring xenobiotics, for example, pyrethrins, nicotine, and various mycotoxins, will be subject to the same toxicokinetic processes.
