Specific issues in health risk assessment of EDCs and correlated international activities thereof are discussed. Risk characterization is a synthesis of all information including hazard assessment, dose-response relationship, and exposure information to identify clearly the strengths and weaknesses of the database, the criteria applied to evaluation and validation of all aspects of methodology, and the conclusions reached from the review of scientific information. In the case of EDCs, new models need to be developed taking into account possible new kinds of information, e.g., effects of EDCs on gene activation in response to hormonal challenge or effects on receptor expression. Such models should also account for homeostatic adaptive responses and consider the possibility of having windows of exposure for given effects. Work to compile and harmonize the definitions and terms appropriate to endocrine disruption will be conducted within the joint IPCS/OECD project on harmonization of risk/hazard assessment terminology reviews. The ICPS is the process of preparing a "State of the Science" report, and is implementing a global inventory of ongoing research on ECDs.