Many of the problems that face decision-makers, in both the industrial and policy sectors, are complex and multi-facetted. In the face of these complexities, traditional methods of risk assessmenti are inadequate, and can lead to narrowly-conceived decisions, and major surprises in terms of health (and wider societal) impacts. One way of avoiding these failures is to use more integrated and forward-looking methods of assessment, designed to answer the ‘what happens if …’ question.