Practical Hazard Assessment for Combined Exposure to Chemical Substances

Abstract

Current risk assessment practices are largely based on evaluating the toxicity of single chemicals. However, humans and environmental organisms are simultaneously exposed to a large number of chemicals. In the case of mixtures, it has long been pointed out that a single chemical substance may cause unanticipated health effects and that the hazards of mixtures cannot be properly assessed. Although there is currently no globally unified method for handling and evaluating mixtures, various evaluation methods have been proposed, mainly by the World Health Organization (WHO), Europe, and the United States. The present report outlines the actual evaluation of mixtures, focusing on their hazardous properties, based on the handling and evaluation methods of mixtures being worked on by overseas organizations and others.