The transfer of polychlorinated dibenzo-p-dioxins and dibenzofurans from soil into eggs of foraging chicken.

The levels of the 2,3,7,8-chlorosubstituted PCDD/Fs (polychlorinated dibenzo-p-dioxins and dibenzofurans) were determined in eggs of foraging chicken and in the corresponding soils. Compared to eggs from hens kept without soil contact the determined levels were clearly elevated. These increased levels were attributed to soil related PCDD/F uptake and were used to deduce congener specific factors describing the transfer from soil into the eggs by the foraging. Based on these transfer factors an calculation method allowing the prediction of the 2,3,7,8-TCDD toxic equivalent (I-TEq) levels in eggs based on the PCDD/F concentrations in soil was developed. The comparison of predicted and determined PCDD/F levels was used to discuss limitations and uncertainties of the model. Based on a given soil contamination, this approach allows a conservative prediction of the I-Teq levels in eggs of foraging chicken.