Potential biomagnification of PCDD/Fs - new possibilities for quantitative assessment using stable isotope trophic position

The transport of PCDD/Fs in two Baltic food chains is studied with a new method which quantitatively estimates biomagnification. Metabolic fractionation of stable isotopes of nitrogen is used to numerically estimate the trophic position of organisms. An application of the method to PCDD/F data from two Baltic food chains indicates that summed whole body concentrations of 2378-substituted PCDD/Fs decrease with increasing trophic position. The sum of TEQs however increases with trophic position. The main reason for this is the decrease in OCDD concentrations and a selective biomagnification of the three most toxic isomers 2378-TCDD, 23478-PnCDF and 12378-PnCDD.