Commentary: barriers and opportunities to changing the research agenda to support precaution and primary prevention.

Conceptual research to define the Precautionary Principle and its role in science, science policy, and public health is making substantial progress. In September 2001, participants at the International Summit on Science and the Precautionary Principle developed a vision for science to address the complexity of contemporary health risks in a way that could lead to more precautionary, preventive decisions under uncertainty. Its components include: 1) a more effective linkage between research on hazards and research on primary prevention; 2) increased use of interdisciplinary approaches including better integration of qualitative and quantitative data; 3) innovative methods for analyzing cumulative and interactive effects, populations and systems and vulnerable sub-populations; 4) systems for continuous monitoring to avoid unintended consequences of actions and to identify early warnings of risks; 5) more comprehensive techniques for analyzing and communicating hazards and uncertainties; and 6) a more dynamic interface between science and policy. This article addresses barriers and opportunities to the practical application of this vision for science. Scientists in many fields have recognized the need for innovative approaches and tools to address increasingly complex, uncertain risks of a global scale. While opportunities to apply precautionary concepts in the research agenda exist, public health scientists must be cognizant of current and emerging barriers in the research agenda that balance the research focus on characterizing proximate causal mechanisms of disease, to the detriment of research and policy to support primary prevention.