That residues of pesticide and other "foreign" chemicals in foodstuffs are of concern to everyone everywhere is amply attested by the reception accorded previous volumes of "Residue Reviews" and by the gratifying en­ thusiasm, sincerity, and efforts shown by all the individuals from whom manuscripts have been solicited. Despite much propaganda to the contrary, there can never be any serious question that pest-control chemicals and food­ additive chemicals are essential to adequate food production, manufacture, marketing, and storage, yet without continuing surveillance and intelligent control some of those that persist in our foodstuffs could at times conceivably endanger the public health. Ensuring safety-in-use of these many chemicals is a dynamic challenge, for established ones are continually being displaced by newly developed ones more acceptable to food technologists, pharma­ cologists, toxicologists, and changing pest-control requirements in progressive food-producing economies. These matters are also of genuine concern to increasing numbers of governmental agencies and legislative' bodi~s around the world, for some of these chemicals have resulted in a few mishaps from improper use. Adequate safety-in-use evaluations of any of these chemicals persisting into our food­ stuffs are not simple matters, and they incorporate the considered judgments of many individuals highly trained in a variety of complex biological, chemi­ cal, food technological, medical, pharmacological, and toxicological dis­ ciplines.