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(80-24) Maternal Transfer and Embryonic Mobilization of Organochlorines in Avian Species, Predictions of Exposure Based on Chemicals in the CAM. Bargar, Timothy*,1, Scott, Geoffry2, Cobb, George3, 1 USEPA, Washington, DC, United States2 Texas Tech University, Lubbock, Texas3 CCEHBR/NOS/NOAA/DOC, Charleston, South Carolina, United Staes ABSTRACT- Predicting avian exposure to chlorinated chemicals utilizing regressions between chemical concentrations in chorioallantoic membranes (CAMs), eggs, and adults requires an understanding of factors that affect those regressions. We present a synthesis of data, primarily from our laboratory studies but with some data from published field research, which demonstrates how chemical structure can affect the regression. Polychlorinated biphenyl (PCB) levels in CAMs vs eggs (r2=0.87) and in CAMs vs adult white leghorn chicken hens (r2=0.91) (Gallus domesticus) were strongly related. In order to be utilized in the field, regression coefficients need to be similar among species. Comparisons among results from laboratory and field studies revealed that the regressions are similar across multiple species. What non-species factors might affect the regressions? Laboratory studies with white leghorn chickens revealed that PCB chlorination, chemical susceptibility to metabolic degradation, and maternal body burdens influenced both maternal excretion of chemicals into eggs and chemical absorption and distribution within developing eggs. These relationships were evident in (1) the relative absolute chemical mass excreted into eggs, (2) egg:hen and yolk+albumin:embryo concentration ratios, and (3) rate of change in chemical mass within egg compartments. These laboratory data support field data. Together, they indicate how chemical structure influences the regression between chemical levels in CAMs and eggs. In conclusion, the regression of chemical concentrations among CAMs, eggs, and adults will be directly proportional to the bioaccumulative potential of the chemical. The regression will be weaker and will be a less accurate predictor of avian exposure for less bioaccumulative chemicals. Key words: CAMs, birds, exposure assessment, PCBs |
