Associated minerals in chrysotile deposits and their potential health risks
Bibliographic record
Abstract
Chrysotile samples from different deposits and the UICC-A and UICC-B standards have been analyzed by a procedure in which the chrysotile is removed by successive treatments in hydrochloric acid and sodium hydroxide, followed by transmission electron microscopy (TEM) examination of the residues. Two separate TEM fiber counts of a minimum of 100 fibers each were made for each sample: fibers longer than 5 μm and fibers with lengths between 0.5 μm and 5 μm. The tremolite/actinolite in each sample was quantified in terms of fibers/gram of chrysotile and as mass fraction in parts per million (ppm). Chrysotile from almost all of the commercial deposits examined was found to contain tremolite/actinolite. In particular, UICC-B Canadian chrysotile was found to contain an average of approximately 180 ppm tremolite/actinolite, equivalent to 1.25 × 107 fibers per gram (longer than 5 μm) of tremolite/actinolite, a proportion of which is asbestiform. The results also showed that both the UICC-B and UICC-A chrysotile standards are contaminated by Amosite. The primary grades of chrysotile from Coalinga, United States, and Minaçu, Brazil, were found to contain substantially less than 1 ppm of tremolite/actinolite. An asbestiform variety of the pyroxene diopside was detected in chrysotile from the Balangero mine in Italy. The asbestiform diopside has a fiber concentration and mass fraction comparable to those of tremolite/actinolite in chrysotile from other sources. Some of the diopside fibers are considerably longer than the tremolite/actinolite fibers found in other sources of chrysotile. Low levels (<4 ppm) of tremolite/actinolite were detected in Balangero chrysotile. No fibers with compositions consistent with Balangeroite were detected. It was found that Balangeroite does not survive the acid-alkali dissolution procedure, and it probably has durability comparable to that of chrysotile. Publications that claim the absence of tremolite/actinolite in UICC-B chrysotile were based on analytical methods that had insufficient sensitivity. Use of these analytical methods permitted only a 1 in 5 chance that a single tremolite/actinolite fiber would be detected. The concentrations of tremolite/actinolite and Amosite found in the reference UICC chrysotile standards raise questions as to the validity of historical biological experiments carried out using these materials.
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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 | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 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".