Emissions of PCDDs and PCDFs from the pulp industry

Samples of pulp and process liquors collected at various sites in a mill producing bleached softwood kraft pulp were analyzed with respect to PCDDs and PCDFs. The results comprised 22 different isomers including all 12 known as particularly toxic. The results show that minor amounts of PCDDs and PCDFs indeed are formed during the bleaching of pulp. The isomer pattern, being dominated by 2,3,7,8-TCDF and 2,3,7,8-TCDD is characteristic and easily distinguishable from the isomer pattern normally found for incineration samples. Compared to other sources for PCDDs and PCDFs in Sweden the amounts formed in pulp bleaching are small.