2,3,7,8-TETRACHLORODIBENZO-P-DIOXIN EQUIVALENTS IN EXTRACTS OF BALTICWHITE-TAILED SEA EAGLES

Concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin-(TCDD) equivalen ts were measured in extracts of Baltic white-tailed sea eagle tissues. Extracts of salmon, ringed seal, and grey seal were analyzed as other predatory species of the same area. Concentrations in eagle and seal tissues were greater than those in salmon. Concentrations of TCDD equi valents (TCDD-EQs) determined by the H4IIE bioassay were compared with toxic equivalents (TEQs) derived from instrumental chemical analyses in fractions containing polychlorinated dibenzo-p-dioxins and polychlo rinated dibenzofurans (PCDD/PCDF) or coplanar polychlorinated biphenyl s (PCBs). Toxic equivalents were calculated by use of an additive mode l in which the product of the concentrations of instrumentally measure d individual congeners were multiplied by their TCDD equivalency facto rs and were summed to give a total concentration of TEQs. The TCDD-EQs were compared with TEQs to develop a mass balance to determine whethe r all the TCDD-like activity was accounted for. For example, the conce ntration of TCDD-EQs in the coplanar PCB fraction of the most contamin ated eagle was 980 pg/g fresh weight (fw), and that of the PCDD/PCDF f raction was 240 pg/g fw. The TEQs determined by chemical analyses for coplanar PCBs was 770 pp/g fw, and that of PCDD/PCDFs was 270 pg/g fw in this eagle. Thus, concentrations of TCDD-EQs were approx. 20% great er than those of TEQs. The true difference in activities is probably g reater because of lower recoveries and infra-additivities among congen ers in the bioassay. This indicates that there are compounds present i n the extracts that can contribute to the total concentrations of TCDD -EQs that were not accounted for by TEQs. The hazard quotient, calcula ted as the ratio of current concentrations of TCDD-EQs in white-tailed sea eagle eggs to the no-observable-adverse-effect concentration, ran ged from 7.3 to 141 (mean = 52.7, SD = 43). This indicates that curren t concentrations of TCDD-EQs in these eggs are likely causing adverse effects in the Baltic populations of white-tailed sea eagles. This stu dy indicated that the H4IIE bioassay is useful for monitoring the pres ence and biological activity of TCDD-like compounds in environmental s amples like white-tailed sea eagles.