This publication is concerned with reviewing the basis for decision-making by the Joint Expert Committee on Food Additives (JECFA) of the Food and Agriculture Organization of the United Nations (FAO) and the World Health Organization (WHO). Because the toxicological and chemical characteristics of food additives are the primary concern of the Committee, both aspects are dealt with in this publication, which has been prepared by WHO- and FAO-appointed consultants, assisted by the WHO and FAO secretariats. The major concerns of this monograph are with the testing of chemicals in food and with the evaluation of the test results.