Fundamental to improving drug development (as well as other types of chemical safety) is the concept of using knowledge of biological pathways or networks (systems biology) to improve our understanding of toxicity and disease. In fact, the realization that chemical safety assessment could be improved by shifting to an approach based on an explicit delineation of biological pathways was proposed in 2007 by the National Academy of Sciences in the report Toxicity Testing for the 21st Century: a vision and a strategy.

Since 2007, an international collaboration, the “Adverse Outcome Pathway” (AOP) framework, has developed into a central tool for realizing this vision. The AOP framework provides an effective means to capture, organize and evaluate knowledge relating to biological activity and potential chemical perturbations that may lead to adverse outcomes of regulatory significance. The Organization for Economic Cooperation and Development (OECD) is coordinating a centralized AOP knowledge hub comprised of databases, guidance documents and training materials to support the AOP framework.
A main element of the AOP Knowledgebase is the AOP Wiki, a wiki-based crowdsourcing platform to collect information relating to AOPs. The OECD has developed extensive guidance for using the AOP wiki, the foremost of which is the AOP User’s Handbook. Anyone can see all of the information in the Wiki; for those who would like to leave comments, simple self-registration is required. Those who wish to enter AOP information must request write-privilege by creating an account and filling out an author request form available through the AOP Wiki. Access is granted either via the OECD by acceptance into the formal work plan, or more informally by contacting the current administrator of the AOP Wiki, the Society for the Advancement of AOPs. Authors of AOPs in the Wiki may nominate their AOPs for formal scientific review by OECD.
The AOP program was originally created to address immediate needs in the field of toxicology; however, both the concept and the biological content are equally applicable to the fields of human disease and medicine.
AOP Training
- AOPs 101 – introduction to AOPs, the AOP program, case studies and potential applications
- AOPs 201 – provides a more in-depth discussion of the OECD’s AOP Knowledge-base software, including the AOP Wiki, AOP Explorer and Effectopedia.
AOP Online Courses
SETAC Continuing Education Courses
Other AOP Resources