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PT14 Toxicity of Mixtures
(PT221) Organochlorine contaminants in an extract derived from double-crested cormorant eggs collected in Green Bay, Wisconsin, affect the immune system of chicken embryos.
Speeg, B1, Grasman, K1, Bowerman, W2, Tillitt, D3, 1 Wright State University, Dayton, OH, U.S.A2 Clemson University, Clemson, SC, U.S.A3 US Geological Survey, Columbia, MO, U.S.A
ABSTRACT- Organochlorines are widespread environmental contaminants associated with immunomodulation in wild and captive birds. Environmental samples of organochlorines often consist of complicated mixtures of contaminant congeners in varying concentrations. In 1995, 1,001 double-crested cormorant eggs (Phalacrocorax auritus) were collected from Spider Island in Green Bay, WI. The contents of the eggs were combined to create an extract containing organochlorine contaminants at biologically relevant levels. Fertilized chicken eggs were injected on day 0 of incubation with different concentrations of the egg extract and incubated until one day before hatch. The primary immune organs, the thymus and Bursa of Fabricius, were weighed, and lymphoid cellularity was determined by Trypan blue exclusion and quantification on a hemacytometer. A dose of PCB 126 known to cause lymphoid atrophy was injected as a positive control. The egg extract produced a significant dose-dependent decrease in body mass. Immune organ mass and cellularity also decreased significantly with dose. Viable lymphoid cells in the bursa were decreased 74.9% at the highest dose group compared to control, while viable lymphoid cells in the thymus were decreased 54.8% at the highest dose group compared to control. The 0.84 ng/g egg PCB 126 dose caused significant reduction in the immune endpoints examined compared to controls, but did not produce significantly different effects than high egg extract doses. These data suggest that environmentally relevant mixtures of organochlorines can cause immunomodulation in chickens.
Key words: PCB 126, immunotoxicology, egg injection, double-crested cormorant
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