The Organization for Economic Cooperation & Development (OECD) is promoting a method to decrease the cost of chemical toxicity testing and the use of animals in such tests. The Paris-based organization, which serves as a forum for governments to find solutions to global problems, released voluntary guidance on March 22 to help regulators and scientists incorporate toxicity pathways into chemical hazard assessments. The method uses “adverse outcome pathways,” defined as a series of events initiated by exposure to a chemical. Such events can result in effects at the molecular, cellular, organ, organism, or population level. By unraveling the sequences of key events, scientists can better understand how chemicals exert their toxicity. High-throughput, cell-based assays and other alternative toxicity tests that don’t rely on animals should be based on knowledge of these mechanisms, the guidance states. OECD is working with the U.S. EPA and the European Commission’s Joint Research Centre to develop a web-based database of known toxicity pathways. The organization is encouraging researchers to develop integrated approaches to toxicity testing that include these pathways as well as structural information.