THE IMPACT OF MATERNAL LEAD EXPOSURE ON THE SECONDARY SEX RATIO OF OFFSPRING
Bibliographic record
Abstract
ISEE-148 Introduction: A reduction in the secondary sex ratio (the proportion of births that are male) is thought to represent pathology involving the conceptus and has been associated in some studies with exposure to dioxins, PCBs and other toxicants. Little data exists, however, relating this outcome to lead exposure, a well-known reproductive toxicant. Methods: We studied 1971 women having singleton births from 1994 to 1995, and from 1997 to 2001, who participated in a cohort study of lead exposure and infant outcomes in Mexico City. Levels of lead were measured in maternal and cord blood using graphite furnace atomic absorption spectroscopy, and levels of lead in maternal patella and tibia bone (a reflection of cumulative exposure) were measured using non-invasive K-x-ray fluorescence measurements. Using logistic regression models, we evaluated the relations of these measures to secondary sex ratio in the offspring, adjusting for maternal age, parity and year of infants’ birth. Results: We found no consistent association between any of the lead measures and secondary sex ratio. For example, mean (SD) levels in the first through fifth quintiles of maternal blood were 3.8 (0.9), 5.8 (0.4), 7.3 (0.4), 9.2 (0.7) and 15.0 (4.5) g/dL, and the corresponding % male births of the children in these quintilesμ were 0.485, 0.513, 0.595, 0.519 and 0.537 (ptrend = [0.34]). Results were unchanged when we adjusted for infants’ year of birth, maternal age and parity. Conclusion: Biomarkers of maternal and foetal lead exposure are not associated with a lower secondary sex ratio among newborns.
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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 | 0.004 | 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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".