Much emphasis is currently given to the question of how available scientific information should be used to inform and support the development of public policy. The interface between the scientific community and policy-makers poses several challenges. In order to overcome the difficulties due to differences of values, language, and purposes, it is important to formulate workable questions and achievable objectives. Effective and ethical use of scientific evidence is desirable, but the complex social and cultural context where decisions are made in modern society must be taken into consideration. A marked trend in European policy-making in environment and health has taken place in the last two decades: besides specific hazardous agents and exposures, the health implications of broad, upstream determinants such as sectoral policies are attracting growing attention. Consequently, essential tools to support rational decision-making, such as risk assessment, need to be supplemented by tools capable of dealing with the additional complexity and uncertainty. Indications and guidance on how to take forward the agenda for action in environment and health in Europe have been made by the series of Ministerial Conferences on Environment and Health, where the 52 Member States of the Regional Office for Europe of the World Health Organization set the priorities and identify common grounds to improve human health and pursue sustainability.