Over 20 years have elapsed since aspartame was approved by regulatory agencies as a sweetener and flavor enhancer. The safety of aspartame and its metabolic constituents was established through extensive toxicology studies in laboratory animals, using much greater doses than people could possibly consume. Its safety was further confirmed through studies in several human subpopulations, including healthy infants, children, adolescents, and adults; obese individuals; diabetics; lactating women; and individuals heterozygous (PKUH) for the genetic disease phenylketonuria (PKU) who have a decreased ability to metabolize the essential amino acid, phenylalanine. Several scientific issues continued to be raised after approval, largely as a concern for theoretical toxicity from its metabolic components--the amino acids, aspartate and phenylalanine, and methanol--even though dietary exposure to these components is much greater than from aspartame. Nonetheless, additional research, including evaluations of possible associations between aspartame and headaches, seizures, behavior, cognition, and mood as well as allergic-type reactions and use by potentially sensitive subpopulations, has continued after approval. These findings are reviewed here. The safety testing of aspartame has gone well beyond that required to evaluate the safety of a food additive. When all the research on aspartame, including evaluations in both the premarketing and postmarketing periods, is examined as a whole, it is clear that aspartame is safe, and there are no unresolved questions regarding its safety under conditions of intended use.

During the American College of Toxicology's Symposium on Endocrine Modulators (Valley Forge, PA, November 1996), the speakers evaluated relevant scientific information and discussed three general ideas, as follows: (1) The available epidem iological data are inconsistent with significant increases in observed human health effects that might relate to the modulation of the endocrine system. (2) Environm ental contarn in ants have produced toxic effects in wildlife at specific locations. In select instances, the adverse effects observed may involve modulation of endocrine pathways. (3) Additional research focused on endocrine modulation is desirable in order to address this issue within a sound, scientificframework.