DIOXIN MEASUREMENTS IN RELATION TO THE COMMONWEALTH GUIDELINES FOR NEW BLEACHED EUCALYPT KRAFT PULP-MILLS

Analysis of filtrates from laboratory bleaching of eucalypt kraft pulp with a sequence employing 70% chlorine dioxide substitution showed that there were non-detectable levels (less than 2 ppq) d 2,3,7,8-TCDD and 2,3,7,8-TCDF. The only chlorinated dioxins and furans present were background levels of compounds with very low toxicity. A crab was collected from each of three different locations in south-east Australian waters and their hepatopancreases analysed for dioxins. The values (measured as total toxicity equivalents) were about 0.4 ppt for crabs from a pristine site and 11 ppt for a crab from a site adjacent to an urban area. Although these data are limited, it is concluded that the level of 5 ppt set in the Commonwealth Guidelines as a trigger level for an investigation is reasonable. Overseas experience in the regulation of dioxin is reviewed. On the basis of a study by Environment Canada it is recommended that the Commonwealth Guidelines for New Bleached Eucalypt Kraft Pulp Mills set a level of 15 ppq for 2,3,7,8-TCDD in the liquid effluent.