Short term temporal variability of selected organophosphate esters among healthy adults living in the National Capital Region of Canada
Bibliographic record
Abstract
Organophosphate esters (OPEs) are used primarily as flame-retardants and plasticizers. OPEs are commonly detected in various environmental matrices, food and drinking water, and their metabolites are frequently found and quantified in urine. Potential adverse impacts on human health, including carcinogenicity, neurotoxicity, developmental and reproductive toxicity have been well documented. Urinary concentration of OPE metabolites can vary in the same individual, depending on the sampling time, thus introducing significant uncertainty in exposure assessment. The current study focusses on the assessment of short term temporal variability in adult men and women residing in Canada's Capital Region. Fifteen OPE metabolites were analyzed in 562 daily urine samples, collected every three days for five weeks from 11 volunteers. Sample extraction procedure was performed on an automated SPE and extracts analyzed using UPLC-MS/MS. In spot urine samples as well as first morning void (FMV), the detection frequency was greater than 50% for bis (2-chloroethyl) hydrogen phosphate (BCEP), bis (1-chloro-2-propyl) phosphate (BCIPP), bis (1,3-dichloro-2-propyl) phosphate (BDCIPP), diphenyl phosphate (DPHP) and bis(2,4-ditert-butylphenyl) hydrogen phosphate (B2,4DtBPP). Significant difference was observed in males and females for BCEP and BCIPP. Intra-class correlation coefficient (ICC) for creatinine corrected data for the spot urine samples ranged from 0.37 to 0.69. Good reproducibility was observed for creatinine corrected DPHP and BCIPP in both spot urine and FMV samples. More variation was observed between study participants in the spot urine samples when compared to the FMV samples. However, when considering diurnal difference there was a considerable inter-day variation in the FMV samples compared to the spot samples. The strength of the study is that the participants belonged to the same geographical location and working in the same facility, hence spatial variability did not influence the outcome of the results.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 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".