The Biopersistence of Canadian Chrysotile Asbestos Following Inhalation
Notice bibliographique
Résumé
Chrysotile asbestos is often included with other asbestos materials in evaluation and classification. However, chrysotile is a serpentine with markedly different physical and chemical characteristics in comparison to amphiboles (e.g., crocidolite, amosite, tremolite). In contrast to amphiboles, which are solid, rodlike fibers, chrysotile is composed like a rope of many fine fibrils, which tend to unwind. In order to quantify the dynamics and rate by which chrysotile is removed from the lung, the biopersistence of a sample of commercial chrysotile from the Eastern Townships area of Quebec, Canada, labeled QS Grade 3-F, which is the longest commercial grade intended for textile use, was studied. As the long fibers have been shown to have the greatest potential for pathogenicity, the chrysotile samples were specifically chosen to have more than 200 fibers/cm3 longer than 20 micro m present in the exposure aerosol. This publication presents the results of this study through 3 mo postexposure. The study design included: (1) Fiber clearance (lung digestions): At 1 day, 2 days, 7 days, 14 days, 1 mo, 3 mo, and 12 mo (to be reported) following a 5-day (6 h/day) inhalation exposure, the lungs from groups of animals were digested by low-temperature plasma ashing and subsequently analyzed by transmission electron microscopy for total chrysotile fibers number in the lungs and chrysotile fiber size (length and diameter) distribution in the lungs. (2) Fiber distribution (confocal microscopy): This procedure was included in order to identify the location of the fibers in the lung. At 1 day, 2 days, 7 days, 14 days, 1 month, and 3 months (to be reported) postexposure, the lungs from groups of animals were analyzed by confocal microscopy to determine the anatomic fate, orientation, and distribution of the retained chrysotile fibrils deposited on airways and in the parenchymal region. Chrysotile was found to be rapidly removed from the lung. Fibers longer than 20 micro m were cleared with T(1/2) = 16 days, most likely by dissolution and disintegration into shorter fibers. The shorter fibers were also rapidly cleared from the lung, with fibers 5-20 micro m clearing even faster (T(1/2) = 29.4 days) than those <5 micro m in length. The fibers <5 micro m in length cleared at a rate (T(1/2) = 107 days) that is within the range of clearance for insoluble nuisance dusts. The breaking apart of the longer fibers would be expected to increase the short fiber pool and therefore could account for this difference in clearance rates. The short fibers were not found clumped together but appeared as separate, fine fibrils, occasionally unwound at one end. Short free fibers appeared in the corners of alveolar septa, and fibers or their fragments were found within alveolar macrophages. The same was true of fibers in lymphatics, as they appeared free or within phagocytic lymphocytes. Neutrophil-mediated inflammatory response did not occur in the presence of chrysotile fibers at the time points examined. Taken in context with the scientific literature to date, this report provides new robust data that clearly support the difference seen epidemiologically between chrysotile and amphibole asbestos.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».