Technological advances in food science have resulted in the development of numerous food additives, most of which require premarket approval by the Food and Drug Administration (FDA). Concomitant with the benefits of these additives, such as extending the shelf life of certain food commodities, is the potential for various risks. These potential risks include the possibility of the consumer experiencing an adverse reaction to the additive. In order to ascertain the character and the gravity of alleged adverse reactions to food products which it regulates, the FDA's Center for Food Safety and Applied Nutrition has developed the Adverse Reaction Monitoring System (ARMS). This postmarketing surveillance system for food additives is designed to analyze consumer reports of adverse reactions in order to alert FDA officials about any potential public health hazard associated with an approved food additive, and to delineate specific syndromes which may lead to focused clinical investigations. To date, among the products routinely monitored in the ARMS, sulfiting agents and the artificial sweetener aspartame have generated the largest volume of consumer reports describing adverse reactions. An overview of the analyses of the sulfite and aspartame adverse reaction reports is presented, along with a description of the mechanics of the postmarketing surveillance system, and a detailed discussion of its limitations.