A scientific workshop was held in 2006 to discuss the use of in vitro Absorption, Distribution, Metabolism, and Excretion (ADME) data in chemical bioaccumulation assessments for fish. Computer-based (in silico) modeling tools are widely used to estimate chemical bioaccumulation. These in silico methods have inherent limitations that result in inaccurate estimates for many compounds. Based on a review of the science, workshop participants concluded that two factors, absorption and metabolism, represent the greatest sources of uncertainty in current bioaccumulation models. Both factors can be investigated experimentally using in vitro test systems. A variety of abiotic and biotic systems have been used to predict chemical accumulation by invertebrates, and dietary absorption of drugs and xenobiotics by mammals. Research is needed to determine whether these or similar methods can be used to better predict chemical absorption across the gills and gut of fish. Scientists studying mammals have developed a stepwise approach to extrapolate in vitro hepatic metabolism data to the whole animal. A series of demonstration projects was proposed to investigate the utility of these in vitro-in vivo extrapolation procedures in bioaccumulation assessments for fish and delineate the applicability domain of different in vitro test systems. Anticipating research progress on these topics, participants developed a "decision tree" to show how in vitro information for individual compounds could be used in a tiered approach to improve bioaccumulation assessments for fish and inform the possible need for whole-animal testing.
Bibliographical noteFunding Information:
This workshop was co-sponsored by the International Life Sciences Institute— Health and Environmental Sciences Institute (ILSI-HESI) and the Society of Environmental Toxicology and Chemistry (SETAC), and was organized by an ILSI-HESI Emerging Issues Bioaccumulation Workgroup. Financial support for the workshop was provided by ILSI-HESI. We thank the individuals who participated in the workshop, most of whom did so at their own expense. We also thank Dr. Keith Sappington and Dr. Larry Burkhard for constructive reviews of this report. The information in this document has been funded in part by the U.S. Environmental Protection Agency.
Copyright 2008 Elsevier B.V., All rights reserved.