The BEACON project will address the biological effects of contaminants, a key topic that provides an understanding of the broad impact of multiple mixed effects of contaminants on Baltic Sea biota. The project partnership includes national organisations responsible for monitoring, brings together Ministry and Agency level associate partners, and includes the HELCOM Regional Sea Commission (RSC) Secretariat. National institutions for which the work is expected to be relevant (e.g. industry, waste water treatment, fire/emergency response organisations, port authorities) will be targeted. The project will take direct contact with stakeholders, practitioners and managers to evaluate their needs and barriers in addressing mixed effects of contaminants, will summarise available methodologies and carry out a pilot evaluation of an integrated biological effects of contaminants, and finally return all findings and recommendations to the stakeholders. By providing the information to those stakeholders identified in the project and relevant RSC groups (e.g. HELCOM State and Conservation, EG Hazardous substances, and EG Economic and Social Analyses) it will set the scene for recommendations on harmonised procedures to be implemented at the municipal, national or regional level, increasing the capacity of these organisations, and establishing the foundations of a long-term practical approach for addressing the multiple mixed effects of contaminants on Baltic Sea biota.