Effects of Postnatal Exposure to Mixtures of Non-ortho-PCBs, PCDDs, and PCDFs in Prepubertal Female Rats
Bibliographic record
Abstract
There are concerns that postnatal exposure to organochlorines present in breast milk could lead to adverse health effects. We reconstituted four mixtures of aryl-hydrocarbon receptor (AhR) agonists (3 non-ortho polychlorinated biphenyls [PCBs], 6 polychlorinated dibenzodioxins [PCDDs], 7 polychlorinated dibenzofurans [PCDFs], or all 16 chemicals together [referred to as AhRM]) based on their concentrations in breast milk, and examined their effects following exposure by gavage from day 1 until day 20 of age. Female neonates received dosages of AhRM equivalent to 1, 10, 100, or 1000 times the amount consumed by an infant over the first 24 days of life. Other groups received the PCBs, the PCDDs, or the PCDFs at the 1000x level. All rats were sacrificed at 21 days of age. Changes in ethoxyresorufin-o-deethylase hepatic activity, thymus and body weights, and serum thyroxin were linked to the 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) toxic equivalents (TEQ) of the four mixtures (1000x-AhRM > PCDDs > PCBs > PCDFs). To test for AhRM antiestrogenicity, two additional groups received 1.5 microg/kg of 17alpha-ethynyl estradiol (EE) with or without the 1000x-AhRM. The AhRM had no effect on uterine weight or EE-stimulated uterine growth. The actions of the combined EE and AhRM treatments suggest additive effects in decreasing pentoxyresorufin-o-deethylase activity and spleen weight, but nonadditive/antagonistic effects on adrenal weight and serum thyroxin. In conclusion, (1) 10x-AhRM had no detectable effects, (2) TEQ values relate to observed toxicities, even when testing complex mixtures of AhR agonists, and (3) indications of tissue-specific additive and nonadditive/antagonistic effects, but no synergism, were observed when doses of AhRM were increased, or combined with EE.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".