The third AMAP Human Health assessment seeks to update the 2002 AMAP Human Health assessment with the latest data and analysis rather than to provide a new independent assessment. The report synthesizes the latest research results from circumpolar countries, building upon previous assessments of environmental chemicals and the variety of their impacts on the health of Arctic populations. Therefore, to benefit most from this work the reader should be familiar with previous assessments. This introduction provides an overview of the critical components upon which this assessment is based and draws heavily on background information from the two previous AMAP assessments of human health in the Arctic (AMAP, 1998, 2003).