- The second arises from the complexity of trying to understand all the factors that are at work, and requires us to examine what we know and how reliable we know it.

- The third derives from the uncertainty that will always exist given that we do not control every factor. This is where the precautionary principle should be brought into play.: the different stakeholders have to think the issues over and negotiate a way forward. But precaution should not be a cover for arbitrary regulation or the dismissal of scientific evidence.

- The fourth type of risk stems from ambiguity in interpreting the meaning and value of research outcomes, and this only a broad debate in society can resolve.

Take a look at his general model of a Risk Governance Framework, or read the Zirn and Dialogik newsletter (pdf) from his institute.