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1.
Arch Environ Occup Health ; 77(4): 268-275, 2022.
Article in English | MEDLINE | ID: mdl-33435788

ABSTRACT

Asbestos ore was sampled from a historical anthophyllite mine in Staten Island, New York. High-resolution transmission electron microscopy (HRTEM) was used to image the structure of nineteen fibers of the anthophyllite asbestos. The anthophyllite was characterized by a high level of chain width disorder, involving wide chain multiplicity faults (CMFs) that were frequent in fibers, randomly spaced, and ranged from one to eight chains in width. This chain width disorder was manifest by streaking of electron diffraction rows of chain width. The anthophyllite asbestos fibers were found to be produced by longitudinal splitting rather than crystal growth. Such splitting is a function of cleavage along CMFs rather than crystal boundaries. The morphology of the fibers is consistent with anthophyllite asbestos mined in Finland associated with lung cancer and mesothelioma. These findings may have regulatory implications.


Subject(s)
Asbestos , Mesothelioma , Asbestos, Amphibole/analysis , Humans , Mesothelioma/chemically induced , Mesothelioma/epidemiology , New York
2.
Toxicol Ind Health ; 36(3): 146-152, 2020 Mar.
Article in English | MEDLINE | ID: mdl-32347168

ABSTRACT

Tremolite-actinolite (TA) fibers from the lungs of deceased former Quebec mine workers were found to be coated with sub-nanometer particles. Qualitative chemical analyses were performed on the particles indicating that they were composed of silicon and oxygen. The crystal lattice structure of all amphibole minerals, including the TA series, is arranged as pairs of linear chains of SiO4 tetrahedra that are linked together to form double chains. Our observations of the TA fibers from miner's lungs, made using a high-resolution transmission electron microscope, indicated that the tetrahedral silica chains were progressively split, forming dispersed sub-nanometer particles. The non-tetrahedral sites were removed at the surface of the TA fibers, presumably by the oxidation process involved in attempted phagocytosis, which also resulted in fragmentation of the tetrahedral chains. It was found that the silicon-rich particles (SRPs) were variable in diameter, consistent with fragments formed from the splitting of the tetrahedral chains. The TA fibers from lungs displayed coatings and linear interior zones of SRP parallel to the planes of longitudinal fiber splitting. The literature on very small nanoparticles is consistent with deep penetration of SRP into cell DNA interiors, oxidative stress, and carcinogenesis.


Subject(s)
Asbestos, Amphibole/adverse effects , Lung/pathology , Occupational Exposure/adverse effects , Silicon Dioxide/adverse effects , Humans , Microscopy, Electron , Miners , Nanoparticles , Quebec
3.
Arch Environ Occup Health ; 75(1): 36-44, 2020.
Article in English | MEDLINE | ID: mdl-30702033

ABSTRACT

Using the recognized amosite standard, we have performed transmission electron microscopy (TEM), scanning electron microscopy (SEM), and chemical analyses. We use high-resolution transmission electron microscopy (HRTEM) and zone-axis selected area electron diffraction (SAED) to describe the molecular structure of the fibers. We find that both microscopic observational evidence and statistical dimensional characteristics indicate that the amosite fibers are formed by longitudinal splitting, with surfaces produced by fine twinning and lateral boundaries formed by parting parallel to the planes of double and triple sheets of amphibole chain structures. Our findings indicate that amosite would not be regulated under current asbestos regulations, which define amphibole asbestos as whole crystals that are not split and that form fibril bundles, not found in our standard. However, it is fully documented that amosite causes mesothelioma, lung cancer, and asbestosis.


Subject(s)
Asbestos, Amosite/chemistry , Microscopy, Electron, Scanning , Microscopy, Electron, Transmission , Molecular Structure , South Africa
4.
J Occup Environ Med ; 61(6): 525-528, 2019 06.
Article in English | MEDLINE | ID: mdl-30985615

ABSTRACT

OBJECTIVE: Our objective is to propose a simple procedure for evaluating potential recent heavy exposure to tremolite. METHODS: One day after an accidental exposure to tremolite in rock dust, sputum was sampled; 3 months later a laryngeal lavage was taken. The sputum was examined with scanning electron microscopy (SEM); the lavage was examined with transmission electron microscopy (TEM). RESULTS: The sputum was found to contain abundant tremolite while the lavage contained very thin, high aspect-ratio fibers, many in the "Stanton Fiber" range. The abundance of tremolite from the larynx suggests accumulation. The thin fibers exhibit splitting from thicker fibers that were in the lungs. CONCLUSIONS: Laryngeal lavage may be an important index of asbestos exposure and is a less complex and more diagnostic alternative to bronchoalveolar lavage or sputum sampling.


Subject(s)
Asbestos, Amphibole/analysis , Occupational Exposure/analysis , Sputum/chemistry , Humans , Larynx , Therapeutic Irrigation
5.
Arch Environ Occup Health ; 70(6): 323-31, 2015.
Article in English | MEDLINE | ID: mdl-25386835

ABSTRACT

The objective of this study is to describe the morphology, molecular structure, and chemistry of amphibole fibers from lung samples from workers in the chrysotile mines at Asbestos and Thetford Mines, Quebec. A fibrous tremolite-actinolite contaminant in an asbestos ore sample from the deposit at Asbestos was used for comparison. Lattice imaging was performed using high-resolution transmission electron microscopy (HRTEM). Silica-rich amorphous coatings (SIRA) that may be related to carcinogenesis are noted on all of the HRTEM photographs of fibers retained in lung, but not on fiber surfaces of the bulk comparison sample. Fibers found in lung samples and in a bulk comparison sample are produced primarily by splitting of thicker crystals and, as such, might not be considered asbestos fibers on the basis of certain mineralogical criteria. Implications of SIRA coatings with respect to carcinogenesis are worthy of further study.


Subject(s)
Air Pollutants, Occupational/analysis , Asbestos, Amphibole/analysis , Lung Neoplasms/ultrastructure , Mesothelioma/ultrastructure , Miners , Occupational Diseases/pathology , Air Pollutants, Occupational/chemistry , Asbestos, Amphibole/chemistry , Cohort Studies , Lung Neoplasms/chemically induced , Lung Neoplasms/pathology , Mesothelioma/chemically induced , Mesothelioma/pathology , Microscopy, Electron, Transmission , Quebec
6.
Med Hypotheses ; 62(4): 629-34, 2004.
Article in English | MEDLINE | ID: mdl-15050120

ABSTRACT

It has been previously proposed that conscious process involves the collapse of quantum, dynamical brain states through conscious observation. It has been further proposed that the brain process has an active role in selecting the status of uncertain stimuli. On the basis of these proposals it was predicted that event-related potentials (ERPs) would differ under unobserved versus pre-observed conditions. This has been found to be the case. Here we describe our most recent data, which shows that the difference between the pre-observed (inactive) and unobserved (active) conditions in ERPs is replicable, and seems to involve a selective process of matching stimulus and virtual brain state under the two conditions. Maximization of entropy by congruence of stimulus and brain potential through a quantum entropy operator is the proposed physical mechanism for this finding. The prefrontal lobe inhibition of perseverative brain states under the active condition is proposed to be the neurological mechanism of the findings.


Subject(s)
Brain/physiology , Evoked Potentials/physiology , User-Computer Interface , Acoustic Stimulation , Computers , Electroencephalography , Electrophysiology , Evoked Potentials, Auditory , Humans , Male , Prefrontal Cortex/physiology , Quantum Theory , Reproducibility of Results
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