Assessing Effects of Endocrine Disrupting Chemicals: Functional Outcomes of Exposure to Mixtures.
Bibliographic record
Abstract
Complex mixtures contain compounds that differ in their biological actions that potentially act synergistically to affect physiological function. Further, birds vary in their vulnerability, utilize a range of lifetime reproductive strategies, and encounter a variety of contaminants especially with migration. It is critical to establish measurement end points responsive to the biological impacts in order to estimate potential risk to individuals and ultimately wildlife populations. We conducted a series of experiments to characterize the effects of polychlorinated biphenyl (PCB) mixtures in birds. Either single PCB congeners or complex PCB mixtures were administered by egg injection to tree swallows, Japanese quail, or chickens. Concentrations administered bracketed those found in eggs collected at the Upper Hudson River environs; comparisons were also made to chicks hatched from eggs collected from contaminated sites. Egg injections were conducted at 18% of embryonic development in field studies and were entirely at the nest sites, with return of eggs to the nest for the remainder of incubation. Samples were collected from hatchlings and measurement end points were chosen to assess target mechanisms. Results showed that PCB mixtures deleteriously impacted embryonic viability in a dose dependent manner. PCB 126 had the greatest impact, followed by the PCB mixtures. Interestingly, PCB 77 had little impact on embryonic development, with the exception of impaired heart development. The domestic chicken was most sensitive, followed by Japanese quail and tree swallows, with the latter two species being relatively similar in their vulnerability to these compounds. Embryonic exposure to the PCB mixtures had deleterious effects on the immune system, thyroid axis, and heart development. Quail raised in one of the laboratory studies showed impaired reproductive function and evidence of impacts on neuroendocrine regulatory systems. The biological impacts of PCBs varied with the congener; complex mixtures reflected the potency of relative proportions of the component congeners. Interestingly, in these and our other studies, it is clear that traditional methods for estimating potential toxicity by Toxic Equivalency Quotient (TEQ) do not accurately reflect the impacts observed in our studies. This may be due to non-aryl hydrocarbon receptor mediated action particularly in the case of endocrine disrupting compounds. We are considering additional methods to assess potential risk for these differing mechanisms of action. Acknowledgements: Research supported by EPA grants R826134010 (Star Grant) and R-82877801; Battelle contract for EPA-EDSTAC validation studies; and U.S. Fish and Wildlife Service. The conclusions and opinions presented here are those of the authors; they do not reflect the official position opinions of the funding agency or the Hudson River Trustees.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".