Updates on exposure estimation for the Québec cohort of chrysotile miners and millers: implications for risk assessment and threshold hypothesis
Bibliographic record
Abstract
The McGill University cohort of Québec chrysotile miners and millers (total of 11,379 members) has been a major determinant of risk assessment. The U. S. EPA and some other meta-analyses omit this cohort, the largest ever exposed to high concentrations of chrysotile. Preliminary analyses using new data showed average cumulative exposures in the full cohort of 528.5 f/cc-years (95% CI 510.3, 546.7) or 979 f/cc-years (95% CI 945, 1,013), depending on the regression equation used for the modeling. The lowest estimated exposure level observed for any mesothelioma case with diagnostic certainty was 68 f/cc-years. We confirmed that the estimation of potency factor for Québec chrysotile should not be expected to differ significantly from Darnton’s estimation for non-textile chrysotile (R M = 0.0014%), if better quality data for correspondence between impinger and fiber count measurements is involved. Among several estimations we made, the average meta-analytical mesothelioma potency factor for all types of chrysotile would be 0.0014% (95% CI 0.0010, 0.0.0018), and for non-textile chrysotile 0.0011% (95% CI 0.0008, 0.0015). Several estimations of a possible threshold that would correspond to non-elevated mesothelioma risk based on the Québec cohort were also made. The minimal cumulative exposure in mesothelioma cases demonstrated values that ranged from 4.8–6 MPCF-years, or 18–50 f/cc-years. Also, based on theoretical models, the threshold can be found at the level of 6.38 MPCF-years (standard deviation 2.6), or in the range from 35.9 f/cc-years (standard deviation of 15.4) to 65.9 f/cc-years (standard deviation of 29.6).
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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 | 0.079 | 0.229 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.002 | 0.005 |
| Bibliometrics | 0.004 | 0.006 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.003 | 0.002 |
| Open science | 0.005 | 0.002 |
| Research integrity | 0.003 | 0.003 |
| Insufficient payload (model declined to judge) | 0.012 | 0.002 |
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".