DIMAS is a 2-year project executed by three Belgian partners (EURAS, VLIZ and Ghent University) and funded by the SPSD II research program of the Belgian Science Policy (BELSPO). Several shipping accidents in Belgian territorial waters, made the various government agencies involved aware of the need to develop tools to assess the risks and impact on marine resources in the case of an accidental release of hazardous substances. DIMAS aims at the protection of the North Sea and Western Scheldt in case of accidental spills from ships. In the present project, a relational database is developed, providing reliable, easy to interpret and up-to-date information on marine specific issues. The database contains the latest information on effects (acute and chronic), absorption, distribution, bioaccumulation/biomagnification, GESAMP hazard profiles and physico-chemical properties for a selection of priority substances and is publicly available ( www.vliz.be/projects/dimas ). The selection of the substances is based on criteria such as occurrence on priority lists, volumes transported over sea, frequency of involvement in accidental spills and frequency of transports over sea. The first beneficiaries of this database are the people directly involved in the first phase of a containment plan for an accidental spill. The final indirect beneficiaries are the general public (scientists, journalists, general public, etc.) who will be better informed about the potential impact to man and the environment.