The overall goal of this regional overview is to provide NOWPAP member states with a synthesis report on a group of chemicals with potential adverse effects to the environment, i.e. persistent toxic substances (PTS). The report covers their sources, transport, environmental levels, potential health risks to humans and environment, management and research activities as well as the gaps on available information and management systems. Particular emphasis has been paid to the possible ecotoxicological effects of PTS in the marine environment of the region.