Risk Analysis 25: 3, 711-718
Decisions are often made even when there is uncertainty about the possible outcomes. However, methods for making decisions with uncertainty in the problem framework are scarce. Presently, safety assessment for a product containing engineered nano-scale particles is a very poorly structured problem. Many fields of study may inform the safety assessment of such particles (e.g., ultrafines, aerosols, debris from medical devices), but engineered nano-scale particles may present such unique properties that extrapolating from other types of studies may introduce, and not resolve, uncertainty. Some screening-level health effects studies conducted specifically on engineered nano-scale materials have been published and many more are underway. However, it is clear that the extent of research needed to fully and confidently understand the potential for health or environmental risk from engineered nano-scale particles may take years or even decades to complete. In spite of the great uncertainty, there is existing research and experience among researchers that can help to provide a taxonomy of particle properties, perhaps indicating a relative likelihood of risk, in order to prioritize nanoparticle risk research. To help structure this problem, a framework was developed from expert interviews of nanotechnology researchers. The analysis organizes the information as a system based on the risk assessment framework, in order to support the decision about safety. In the long term, this framework is designed to incorporate research results as they are generated, and therefore serve as a tool for estimating the potential for human health and environmental risk.