Quaternary Ammonium Compounds in Paired Samples of Blood and Indoor Dust from the United States
Bibliographic record
Abstract
High Resolution Image Download MS PowerPoint Slide Previous studies of quaternary ammonium compounds (QACs) in the indoor environment have reported widespread presence of QAC in indoor dust. However, there are limited data on the contribution of dust ingestion to the QAC body burden. In this study, 18 QACs (6 benzylalkyldimethylammonium compounds [BACs], 6 dialkyldimethylammonium compounds [DADMACs], and 6 alkyltrimethylammonium compounds [ATMACs]) were analyzed in 81 paired samples of blood serum and dust collected in Indiana, United States. QACs were detected in 51–100% of the dust samples with the total QAC concentrations (∑QAC) ranging from 0.613 to 427 μg/g (median 56.9 μg/g). In contrast to dust samples, QACs were detected less frequently in blood serum with a median ∑QAC concentration of 3.66 ng/mL. The relative source contribution (RSC) of dust ingestion to serum levels was calculated using the PROTEX (PROduction-To-EXposure) model and was estimated as less than 1%, suggesting that hand-to-mouth contact, dietary intake, or inhalation could be more important exposure routes than dust ingestion. This is the first study to simultaneously measure QAC concentrations in indoor dust and blood, providing comprehensive assessment of the role of dust ingestion in QAC human exposure.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| 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) | 0.001 | 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 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".