Risks of Birth Defects Following In Utero Exposures to Unregulated Brominated Haloacetic Acids
Bibliographic record
Abstract
INTRODUCTION: Haloacetic acids (HAAs) are water disinfection byproducts (DBPs) regulated as a mixture of five species (HAA5) in the United States and Canada. To date, two brominated HAAs (BrHAAs) in HAA5 (monobromoacetic acid [MBAA], dibromoacetic acid [DBAA]) have been associated with birth defects in some epidemiologic studies, but the other four unregulated BrHAAs remain understudied. METHODS: We analyzed registry-based case-control data on 16 birth defect phenotypes in relation to temporally weighted first-trimester exposures to the four unregulated BrHAAs (tribromoacetic acid [TBAA], bromochloroacetic acid [BCAA], bromodichloroacetic acid [BDCAA], chlorodibromoacetic acid [CDBAA]) and the sum of all six BrHAAs (HAA6 = TBAA + BCAA + BDCAA + CDBAA + MBAA + DBAA). We matched cases to controls 1:10 on the week of conception and estimated adjusted odds ratios (aORs) via conditional logistic regression. RESULTS: We observed some elevated aORs for dichotomized BrHAA exposures with certain outcomes, such as cleft palate alone (BDCAA aOR = 1.75 [95% confidence interval: 1.15, 2.66]), ventricular septal defects (BDCAA aOR = 1.28 [0.97, 1.68]), tetralogy of Fallot (BDCAA OR = 1.57 [0.93, 2.64]), and obstructive genitourinary defects (CDBAA aOR = 1.65 [1.07, 2.53]), and reduced aORs for hypospadias (e.g., BCAA aOR = 0.58 [0.40, 0.84]). Most other associations were closer to the null, and many lacked precision. CONCLUSION: Our observations warrant further investigation given their novelty and the paucity of data on health impacts of prenatal BrHAA exposures overall; ours is the first epidemiological study to investigate most of these exposure-outcome relationships. Future work would benefit from a longer study period to ascertain additional birth defect cases and more direct exposure assessment in areas served by water systems with higher bromide levels.
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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 | 0.001 | 0.005 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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 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".