The aim of the editors of this volume is to use basic and ap- plied studies in the field of mutagenesis to approach a problem of especial concern. The problem is that of the usage of toxic chemi- cals, particularly agricultural chemicals, in ever-increasing quan- tities in those parts of the world that feed the most people. Agri- cultural chemicals that are in use in Pakistan are emphasized here. These are the same chemicals that are in use throughout the develop- ing world, although the quantities of the different types that are used may vary from country to country, and from region to region within countries. A number of these chemicals can longer be sold in Europe or in the United States, and it is often difficult to iden- tify a scientific reason as to why they are sold at all. It is ironic that toxic chemicals are used as a humanitarian device to rid the world of Pestilence and Famine -- two of the Horsemen of the Apocalypse. If we do t wish poisous chemicals to become the fifth Horseman of the Apocalypse, then we must begin w to identify and regulate the large-scale usage of toxic sub- stances everywhere.