A survey of three PCB and dioxin contamination episodes: From contamination of food items to body burdens

Belgian citizens face a high background exposure to dioxins and polychlorinated biphenyls (PCBs). During the past 3 years, three episodes of animal feed contamination have added to this exposure. This chapter calculates the body burdens (body burden defined as the concentration of a persistent substance accumulated in a relevant tissue or body fluid) resulting from these exposures and compares the results with measured body burden data in the Belgian population. Geometric mean PCB (sum of seven indicator congeners) background concentrations in Belgian food items range between 16.6 ng/g fat for milk and 72.1 ng/g fat for poultry. Corresponding geometric mean dioxin concentrations range between 0.8 pg TEQ per g fat for pork and 2.4 pg TEQ per g fat for poultry. On top of this, Belgium has faced three animal feed contamination episodes: a major one in 1999, one in 2000, and one in 2002. During the 1999 crisis, a substantial part of the human food chain was contaminated, with PCB concentrations in poultry up to 56,856 ng/g fat and dioxin concentrations up to 2613.4 pg TEQ per g. In 1999, and to a lesser extent in 2001, occasional incidents of isolated contamination also increased concentrations in food items, the contribution of which to body burdens should not be neglected. Based on background exposure levels, the body burdens of Belgian female adolescents and women (ages 50 to 65) have been calculated. Calculated PCB body burdens are 75.5 μ g/kg body weight for female adolescents and 147.0 μ g/kg body weight for adult women, and dioxin body burdens are 3.7 ng TEQ per kg body weight for female adolescents and 7.1 ng TEQ per kg body weight for women. Measured dioxin body burdens are substantially higher and amount to 8.8 ng TEQ per kg body weight for female adolescents and 14.7 ng TEQ per kg body weight for female adults. The difference between calculated and observed values might stem from higher background levels in the past, from episodes of widespread contamination, and from exposure through other routes. Calculated PCB body burdens are 20% higher than the measured ones (57.1 μ g/kg body weight for female adolescents and 121.6 μ g/kg body weight for women). This difference might be explained by assumptions regarding the half-life of PCBs which overestimate the actual half-life. It was estimated that the 1999 crisis resulted in an increase of PCB body burdens by 28% and of dioxin body burdens by 4.3%. As to PCB body burdens, measurements before and after the crisis are concordant with this estimate.