| Summary: | Summary Background The aim of this study was to determine 17 Polychlorinated Dibenzo- p -dioxin and Dibenzofuran (PCDD/F) and 12 Dioxin-like Polychlorinated Biphenyl (DL-PCB) concentrations in the tissues of Finnish terrestrial herbivore species, semi-domesticated reindeer ( Rangifer tarandus tarandus L.), and wild moose ( Alces alces ), investigate transfer and accumulation of PCDD/Fs and DL-PCBs in milk of the lactating reindeer hinds, and explore contaminant concentrations in stillborn reindeer calves exposed via placental transfer to PCDD/Fs and DL-PCBs. Methods Reindeer and moose tissue sampling was focused in Finnish reindeer herding region. Reindeer milk samples were sampled in summer and autumn from reindeer hinds in experimental reindeer station in northern Finland. PCDD/Fs and DL-PCBs were analyzed using HRGC/HRMS method. The results are reported here as WHO-TEQ upper bound concentrations and congener-specific lower bound concentrations. Results WHO-PCDD/F- and PCB-TEQs in reindeer muscle and liver were generally higher in the calves than in adults. Concentrations in moose calves were lower than in reindeer calves, while in adult reindeer and moose the levels were equal. General PCDD/F congeners in reindeer muscle and liver were 23478-PeCDF, 123678-HxCDD and OCDD. In reindeer milk, the highest PCDD/F detected was OCDD, and it was common also in the moose muscle samples. A strong contribution of non- ortho -PCBs to WHO-TEQ was detected in all studied samples. The most dominating non- ortho -DL-PCB congener was PCB-126 in reindeer muscle, liver and milk. In moose muscle samples PCB-77 was the most abundant congener. Species-, individual- and tissue-specific accumulation of PCDD/Fs and DL-PCBs may be the result from varying extent and quality of exposure, and to some extent from different metabolic potential. Conclusions PCDD/Fs showed partly similar profiles in reindeer and moose muscle, reindeer liver and milk samples - indicating equal mode of bioaccumulation. A strong contribution of non- ortho -PCBs to WHO-TEQ was detected, although there were some differences in frequency of particular congeners in these species. Due to the harmonized sampling method the study offers the way to determine and compare the levels of PCDD/Fs and DL-PCBs in reindeer and moose tissues and examine the transfer and dynamics of dioxins and dioxin-like compounds in northern terrestrial food web.
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