The integration of the adverse outcome pathway framework to radiation risk assessment

A large body of radiobiological data has been generated over the past century using in vitro, animal and epidemiological models. This information represents global efforts to understand the mechanistic basis of radiation-induced health effects. However, it has been difficult to effectively integrate this data to derive meaningful information for refining the guidance on chronic, low dose radiation exposure for workers and the public.

To increase our understanding of radiation risks and the biological processes that contribute to those risks, a paradigm shift is needed that will enable integration of information across levels of biological organization from a 'stressor' centric to an 'adverse outcome' approach to risk assessment. In chemical and ecological toxicity, a framework has been developed that captures available biologically-based knowledge in the literature and links it to outcomes of relevance to chemical toxicity, resulting in an adverse outcome pathway (AOP).

In this paper, we discuss the AOP concept, how it can be applied to the radiation field, and our vision for the next steps. For the approach to be successful, the radiation research community will need to work collaboratively to vet the vast amount of literature and harness the data in a systematic manner for incorporation into a framework based on the AOP approach.

We anticipate that AOPs could be adopted as a method to synthesize current available information to facilitate the identification of knowledge gaps, better co-ordinate research and qualitatively and quantitatively link key events to an adverse outcome. This can further assist in identifying biomarkers relevant to radiation exposures, refining risk from co-exposures and understanding critical events at the molecular, cellular, tissue, organ and whole animal level related to low dose/dose-rate exposures.