SOURCES OF EXPOSURE, ENVIRONMENTAL CONCENTRATIONS AND EXPOSURE ASSESSMENT OF PCDDS AND PCDFS

The major primary sources of PCDDs and PCDFs are chemical, thermal, photochemical and enzymatic reactions. The abiotic secondary sources indicate combustion as the major source. Sewage sludge might be a secondary as well as a primary source. Only 2,3,7,8-substituted compounds are found in higher animals like fish and mammals. The dominating congener found in herring fat from the Baltic Sea is 2,3,4,7,8-pentaCDF, but this congener is not related to pulp bleaching. The human excretion is larger than the estimated intakes. There is a discrepancy in profiles between sources and environmental reservoirs, which cannot be fully explained.