Influence of Bisphenol-A Upon Intrauterine Implantation of Fertilized Ova in Inseminated Female Mice
Bibliographic record
Abstract
P-240 Introduction: Early pregnancy in mammals is vulnerable to environmental and hormonal changes.1 In particular, intrauterine implantation of fertilized ova in female mammals is highly sensitive to exogenous estrogens.2 Pregnancy in female mice can be terminated by nasal or cutaneous doses of 17β-estradiol lower than 0.1 microgram/day in initial days of gestation. Accordingly, we have inquired whether putative estrogenic compounds in industrial processes and domestic products can impact early pregnancy. In particular, bisphenol-A (BPA), the monomer of polycarbonate plastics, can be estrogenic3 and is found in food and human tissues.4–6 We thus designed experiments to examine the response of early pregnancy to systematically varied oral and subcutaneous doses of BPA. Methods: Inseminated female mice were either injected or orally administered doses of BPA on days 1–4 of gestation. Across groups, dose levels increased following a tripling progression. Subcutaneous injections of 0.05–0.15 ml contained BPA doses ranging from 0.04 to 3.38 mg/day/animal dissolved in peanut oil. Oral administration consisted of 1 g peanut butter/BPA mixture with BPA content ranging from 0.11% to 9%. Fresh mixture was hung daily in the cage for females to consume and any remnants weighed. Females were then left undisturbed until parturition. Litter size at birth, neonatal mortality, sex ratio, and whole litter weight were recorded. Results: At all subcutaneous doses up to 1.13 mg/day, there were no significant effects on litter size, neonatal mortality, or other measures. However, a significantly decreased litter size was observed at the 3.38 mg BPA/day/animal subcutaneous dose. Oral doses did not significantly affect the proportion of females that were parturient. However, there were indications of qualitative idiosyncratic impacts of higher oral doses upon maternal behaviour and pup survivorship. Discussion: These data indicate that BPA may have only weak estrogenic properties with respect to intrauterine implantation. A wide range of BPA doses administered orally and by subcutaneous injection have, to date, failed to produce the strong effects that are found for natural estrogens. However, the observed reductions in litter size seen with higher BPA doses do resemble effects of estradiol doses in the transition between normal and complete disruption of pregnancy.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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 source (direct Gemma or distilled Codex), 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".