Lung-Retained Fibre Content in Brazilian Chrysotile Workers
Bibliographic record
Abstract
Introduction. Beginning with observations in Québec in 1976, the study of lung-retained fibre has led to an increased understanding of exposure and disease in chrysotile mining areas. Until 2000 this was confined largely to Québec, but recent work has outlined exposure profiles for lung content in Russian, Chinese and South African chrysotile production and factory workers. We now report the first findings from Brazilian chrysotile production and asbestos cement workers with well characterized clinical, exposure and smoking histories. Methods. Subjects working either in the chrysotile mining industry in Brazil ( n = 6) or in the asbestos cement industry ( n = 4) were admitted to hospital for investigation of pulmonary lesions. Six had benign infections and four lung cancer, while two also had pleural plaques (both miners) and one cement worker had asbestosis. Portions of formalin-fixed lung tissue obtained at surgery or autopsy were obtained for analysis. Asbestos bodies (AB) were quantified following bleach digestion using phase contrast optical microscopy at ×312. Additional portions were examined using transmission electron microscopy at ×14000. Seven hundred and four fibres (aspect ratio > 3:1) were identified and quantified by X-ray energy dispersive spectrometry in three length classes, <5, 5–20 and >20 μm, each at a theoretical detection limit of 0.1 fibres/μg dry lung. Results. AB counts confirmed occupational exposure as proportional to years of exposure ( r = 0.72, P < 0.05), but were far lower than observed in workers elsewhere, possibly due in part to fibre type and to a mean duration of exposure of <10 years. Conversely, non-asbestos ‘fibres’ were much more common than among chrysotile workers elsewhere, averaging 70% of all fibres counted. Chrysotile accounted for >90% of asbestos fibres in all length classes (median 98% of all asbestos fibres; median 4.99 fibres/μg chrysotile versus 0.11 for amphiboles; P < 0.001). As is generally the case, <5 μm fibres were most concentrated (86%). Tremolite was detected in the lung of two mining workers, but only >5 μm in one who worked in a nowabandoned mine known to contain that mineral.
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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 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".