Each of the chapters in this book is capable of standing alone, but when placed together they present a mosaic of the current ideas and research on adverse reactions to foods and food additives. Overlap is unavoidable but, we hope, is held to a minimum. Ideas of one author may sometimes differ from those of another, but in general there is remarkable agreement from chapter to chapter. We, the editors, thus present the fourth edition of a book that we believe represents a fair, balanced, and defensible review of adverse reactions of foods and food additives.