ASSESSMENT OF HUMAN INTAKE OF PCDDs AND PCDFs FROM DIFFERENT ENVIRONMENTAL SOURCES

It is generally agreed that for humans, diet represents the main route of exposure to polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), Usually more than 90% of the total daily intake of PCDDs and PCDFs is derived from food. In contrast, exposure via other routes normally contributes less than 10%., Due to the lipophilic properties of PCDDs and PCDFs and their well-known accumulation in the food chain, food samples of animal origin are of special importance for a risk assessment based on the daily intake.. While, normally, specimens of plant origin only contain very low levels near the detection limit, all samples of animal origin analyzed so far show typical patterns of PCDDs and PCDFs. Predominant congeners are those with 2,3,7,8-chlorine substitution Taking consumption habits into account the average daily intake via food, at least in industrialized countries, is in the range of 1-3 pg TCDD-equivalents (international toxicity equivalence factors, I-TEQ)Ikg body weightlday. This level has been confirmed by various analytical measurements and theoretical estimations using exposure models.. However, the intake can be increased significantly by special consumption habits or migration of PCDDs and PCDFs from packaging material into food.. As a result the actual daily intake via food is in the range of, or exceeds, the tolerable daily intake (TDI) set by health authorities in many countries Contamination of human milk with xenobiotics is of major concern because of its importance as the first foodstuff for breastfed babies In a field study conducted by the World Health Organization's European Regional Office WHOI EURO, human milk samples from ten European countries, Canada, U S.A., and Japan were analyzed. The levels ranged from 8 2-40 2 pg I-TEQ1g fat with a mean value of 22 ..4 pg I-TEQ/g fat Assuming an intake of 800 ml milk with 3% fat this would correspond to an average daily intake of 94 ..1 (34..4-168.8) pg I-TEQ/kg body weight for a baby weighing 5 kg.. This value is far above all proposed TDIs ranging from 0.006-10 pg/kg body weightlday (Barnes 1989) Although the TDI concept, which is based on a lifetime intake, should not be applied to breastfed children, the above-mentioned data, which must be considered as a matter of concern, demonstrate that all efforts should be undertaken to reduce the emissions of PCDDs and PCDFs to levels as low as possible in order to minimize the ubiquitous contamination of the environment and thus, finally, to achieve a reduction of the body burden in humans