Toxicological Interactions of Chemical Mixtures

Abstract

Since the publication of the first book on Toxicology of Chemical Mixtures in 1994 (Yang 1994a), we witnessed, with gratification, the advancement of science in this area, as well as the awareness and implementation of regulatory decisions by the United States Environmental Protection Agency (USEPA) to address issues of multiple chemical (and multiple stressor) exposures. Despite such impressive progress, however, if we focus on one of the examples cited in this chapter, a citizen’s petition on 17 July 1984, under section 21 of Toxic Substances Control Act (TSCA), from Robert Ginsburg and Mary Ellen Montes, we are still far away from answering some of the questions concerning chemical mixture toxicology and risk assessment raised by these laypersons. Looking at another direction at CDC’s Third National Report on Human Exposure to Environmental Chemicals (CDC 2005), neither do we have a satisfactory answer toward the question What is the toxicological significance of the presence of at least 148 chemical pollutants in our body? Thus, we have a great deal of work and challenges ahead of us. In this chapter, we updated the 1997 version based on the scientific advances in the last 12 years. While we face the challenges of this very complex and difficult area of toxicology and risk assessment of chemical mixtures and multiple stressors, new frontiers such as nanotechnology and nanotoxicology came into being. Aspiring young scientists are encouraged to enter this vitally important area as we need talents from all disciplines of science to tackle these nagging problems.