Sources and Relative Importance of PCDD and PCDF Emissions

Polychlorinated dioxins (PCDD) and dibenzofurans (PCDF) have been identified in technical products and pesticides, most of which are not very widely used today. Other sources are incinerators of various types like MSW incinerators, hazardous waste incinerators and industrial incinerators. PCDDs and PCDFs have also been identified in exhausts from cars running on leaded gasoline with halogenated additives. Background levels of PCDDs and PCDFs have been identified in fish and other aquatic organisms from the Great Lakes and the Baltic Sea, and also in human adipose tissue samples from U.S.A., Canada, Sweden, Japan and Vietnam as well as in samples of breast milk from Sweden, Denmark, West Germany, the Netherlands, Yugoslavia and Vietnam. The isomeric pattern in all these biological samples is very similar. The relative importance of different sources to the general background is difficult to estimate although the contribution of direct inhalation from point sources like MSW incinerators is small.