Preliminary Assessment of a Unified Bioaccessibility Method for Potentially Harmful Elements in Soils
Bibliographic record
Abstract
MS1 Symposium Title: Childhood Exposures to Bioavailable Metals in Soil and Household Dust in Residential Environments Symposium Organizers: Pat Rasmussen, Joanna Wragg, and Mark Cave MS1-01 Introduction: When considering the direct ingestion of soil in risk assessment, total concentrations of potentially harmful substances (PHS) are often considered to be a gross overestimate of the amount of PHS entering the body. The human gastrointestinal tract only makes a fraction of the PHS accessible for absorption. U.K. technical guidance, however, permits the use of site-specific estimates of oral bioaccessibility. This presentation describes 2 initiatives being undertaken by the BGS and the Bioaccessibility Research Group of Europe (BARGE) for standardized and validated procedures for measuring bioaccessibility by: 1) preparation of a reference soil to allow testing laboratories to monitor the QA of bioaccessibility measurement; and 2) development of a unified and validated in vitro bioaccessibility test. Reference Soil Description and Methodology: A total of 0.5 tonne of soil, of a similar type to the Banbury series (ferritic brown earth), was collected from North Lincolnshire. The sample was dried, ground, homogenized, and characterized and the total As concentration was found to be 87.1 ± 4.7 mg kg-1 with the bioaccessible As c.5 mg kg-1. Results: The proposed unified procedure has been derived from the RIVM physiologically based in vitro extraction test.1 The performance of the method has been tested on 9 soils for which in vivo arsenic bioavailability data has been obtained using a swine model.2 The soils have been provided by Professor Nick Basta of the Ohio State University, Columbus, Ohio. The soils are calcine and iron slag soils with total As concentrations ranging from approximately 400 to 18000 mg kg-1 and relative bioavailabilities from approximately 4% to 40%. Initial studies have shown that the gastric phase bioaccessibility values from the unified procedure have a correlation coefficient of 0.907 and a regression line slope of 1.2 with the absolute bioavailability data.
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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 | 0.008 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| 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 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".