ABSTRACT
The organic pollutants discussed in this book are examples of xenobiotics. A xenobiotic is here defined as a compound which is ‘foreign’ to a particular organism. This means that it does not play a part in normal biochemistry. By this definition, a chemical which is normal to one organism may be foreign to another. Thus, xenobiotics may be naturally occurring as well as man-made (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 of the organic pollutants referred to in Chapter 1 are man-made xenobiotics-which do not occur in nature. It is, however, important to re-
member that naturally occurring xenobiotics, for example pyrethrins, nicotine, various mycotoxins etc., will be subject to the same toxicokinetic processes.
