ASSESSMENT OF DIOXIN-RELATED HEALTH RISKS FOR THE MELBOURNE METROPOLITAN-AREA

A community health risk assessment was conducted during 1990 in Melbou rne for polychlorinated dibenzo-para-dioxins (PCDDs) and polychlorinat ed dibenzofurans (PCDFs) released in Laverton North by Nufarm Limited, an agricultural chemicals manufacturer. This risk assessment incorpor ated current scientific knowledge into hazard identification, dose-res ponse assessment, exposure assessment and risk characterisation sectio ns, according to the four-step framework used by the United States Env ironmental Protection Agency. The hazard identification showed that he alth effects are unlikely to result from general population exposures to PCDDs and PCDFs. The dose-response assessment supported a safety-fa ctor approach for PCDD and PCDF risk assessment. The exposure assessme nt incorporated exaggerated assumptions to estimate both total daily e xposure (203 pg total toxic equivalents of PCDDs and PCDFs, or 2.9 pg/ kg body weight) and daily exposure attributable to Nufarm (56.4 pg, or 0.80 pg/kg body weight) under a worst-case scenario. The risk charact erisation section found that exposures under 20 pg/kg body weight per day should not induce the aryl hydrocarbon hydroxylase system, which a ppears to be the starting point for PCDD and PCDF toxicity. We conclud ed that the general population exposure to PCDDs and PCDFs in Melbourn e was within the range of acceptable daily intakes used by European an d Canadian governments and the World Health Organization, as well as w ithin the range of acceptable daily intakes derived using current scie ntific knowledge.