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  • 1
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract Great Lakes colonial waterbirds have experienced poor reproduction and a greater incidence of birth defects than those in remote areas. An egg was collected from each of 1,000 marked cormorant nests at Spider Island (Lake Michigan). Nine pools comprised of three eggs were randomly selected for instrumental quantification of polychlorinated biphenyls (PCB) congeners, calculation of 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEq) and measurement of equivalents by bioassay (TCDD-EQ). PCB analysis of the nine samples was semi-automated with high performance liquid chromatography (HPLC) columns including a porous graphitic carbon column. TEqs were calculated from concentrations of PCB congeners and bioassay-derived toxic equivalency factors (TEfs), and TCDD-EQ were measured directly with an H4IIE bioassay. Total PCB concentrations ranged from 9.7 to 38 μg/g, wet weight (ww). Mean concentrations of PCB 77, 126, and 169 were 2, 7, and 1 ng/g, ww. The mean TEqs and TCDD-EQ were 150 and 350 pg/g, ww, respectively. Thus, PCB congeners contributed less than 50% of the total TCDD-EQs as measured by the bioassay.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract The hypothesis that the concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEqs) contributed by non-ortho- and mono-ortho-substituted (coplanar) PCB congeners have changed relative to total concentrations of PCBs over time was tested by analyzing eggs of red-breasted mergansers collected from the same locality in 1977–78 and in 1990. Twelve eggs from each time period were analyzed for coplanar PCBs, using a porous graphitic carbon HPLC column and GCECD. TEqs were calculated from coplanar PCB concentrations and bioassay-derived toxic equivalency factors. Median total PCB concentrations decreased from 25 to 13 μg/g, fresh weight (fw), and TEqs decreased from 320 pg/g to 160 pg/g, fw. The relative potency of the PCB mixtures, expressed as the ratio of TEqs contributed by the coplanar PCB congeners to total PCBs, did not change, nor did the ratio of concentrations of coplanar congeners to total PCBs. Thus, the relative potency of the mixture of PCBs in the eggs has not changed even as the concentrations declined significantly. The greater relative potency of TEqs relative to that which would be expected from the Aroclor® mixtures released into the environment is due to selective bioaccumulation, biomagnification, and metabolism, rather than as a result of differential weathering as a function of time.
    Type of Medium: Electronic Resource
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