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Diet is the major route of exposure to environmental contaminants in biota and, after penetration into an organism, xenobiotics continue to accumulate in the body. In birds the egg-laying process acts as a transfer mechanism for the accumulated pollutants and results in the burdening of the next generation at an early stage of development. This transfer has a strong influence on developmental disorders and even breeding success. With this in mind polybrominated diphenyl ethers (PBDE), polychlorinated dibenzo-p-dioxins and polychlorinated dibenzo furans (PCDD/Fs), as well as polychlorinated biphenyls (PCBs), were analyzed in the eggs of aquatic birds from different habitats and with different diet preferences. The highest concentration of PBDE was noted in gull eggs (198.31 ng g -1 dw.) and the lowest in tern eggs (sandwich tern: 76.96 ng g -1 dw.; common tern: 113.73 ng g -1 dw). Deca-BDE was detected only in herring gull eggs from the Wloclawek reservoir. PCDDF/s were found in the eggs of terns from the southern coast of the Baltic Sea and gulls from an inland reservoir (dam) on the River Vistula close to the town of Wloclawek. The highest toxicity (birds Toxic Equivalent Factor) was found in the eggs of terns (sandwich tern - 93.97 pg g -1 dw., common tern - 68.35 pg g -1 dw.), and this was found to be several times higher than in herring gull eggs (18.80 pg g -1 dw.). Non-dioxin like PCBs were ten times higher than other analyzed PCB congeners, but the congener pattern was similar to other studies., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Alimentary exposure is the main factor determining halogenated organic compound pollution of wildlife, with birds' eggs recognised as bioindicators of these contaminants and often used as a non-invasive monitoring tool. Comparisons of bird species from two aquatic environments, namely a marine coastal area (Gdansk Bay) and an inland reservoir (Włocławek Dam on the Vistula River), indicated significant differences in egg contamination. Herring gull eggs from Włocławek Dam had high concentrations of highly chlorinated dioxin (i.e. octachlorodibenzodioxin, which accounted for 37% of all polychlorinated dibenzo- p -dioxins and polychlorinated dibenzo furans, PCDD/Fs). In contrast, eggs from terns feeding along the coastal area of the Southern Baltic contained high concentrations of lowly chlorinated furans (i.e. pentachlorodibezofuran, which accounted for 46 and 45% of all PCDD/Fs in eggs from the sandwich tern and common tern respectively). The congener patterns in terns' eggs were similar to those reported previously for Baltic fish. Polychlorinated biphenyl congener 180 had the highest concentrations among the mono-ortho chlorinated biphenyls, whereas concentrations of non-dioxin-like chlorinated biphenyls were 10-fold higher than those of the other congeners analysed, but the congener pattern in eggs from both species (sandwich and common tern) was similar to that reported in other studies. Among the hexabromocyclododecane (HBCD) isomers, α-HBCD dominated in all eggs analysed (accounting for >97% of all HBCDs). The total HBCD concentration in gulls' eggs from the inland reservoir was approximately half that in eggs from the common and sandwich terns (mean ± s.d. 47.33 ± 33.22 v. 97.98 ± 59.69 and 104.00 ± 63.66 ng g–1 lipid weight respectively). Alimentary exposure is the main factor determining halogenated organic compound pollution of wildlife. Comparisons of two aquatic environments, namely marine coast (Gdansk Bay) and an inland reservoir (Włocławek Dam on the Vistula River), indicated significant differences in contamination of birds' eggs. Concentrations of polychlorinated dibenzo- p -dioxins and furans as well as polychlorinated biphenyls were similar but TEQ were several times higher in fish eating birds. The same was observed for hexabromocyclododecane isomers [ABSTRACT FROM AUTHOR]