ferroactinolite and Asbestosis

Naturally occurring asbestos (NOA) fibers are found in geologic deposits that may be disturbed by mining, earthworks, or natural processes, resulting in adverse health risks to exposed individuals. The toxicities of Libby amphibole and NOA samples including Sumas Mountain chrysotile (SM), El Dorado tremolite (ED), and Ontario ferroactinolite cleavage fragments (ON) were compared in male Fischer 344 (F344) rats 15 mo after exposure. Rat-respirable fractions of LA and SM displayed greater mean lengths and aspect ratios than ED and ON. After a single intratracheal (IT) instillation (0.5 or 1.5 mg/rat), persistent changes in ventilatory parameters and a significant increase in lung resistance at baseline and after methacholine aerosol dosing were found only in rats exposed to 1.5 mg SM. High-dose ED significantly elevated bronchoalveolar lavage lactate dehydrogenase (LDH) activity and protein levels, while high-dose SM increased γ-glutamyl transferase and LDH activities. A moderate degree of lung interstitial fibrosis after exposure to 1.5 mg SM persisted 15 mo after exposure, unchanged from previous findings at 3 mo. LA induced mild fibrosis, while ED and ON produced minimal and no apparent fibrosis, respectively. Bronchioloalveolar carcinoma was observed 15 mo after exposure to LA or ED. Data demonstrated that SM, given by bolus IT dosing on an equivalent mass basis, induced greater pulmonary function deficits, airway hyperresponsiveness, and interstitial fibrosis than other NOA, although unlike LA and ED, no apparent evidence for carcinogenicity was found. All NOA samples except ON cleavage fragments produced some degree of long-term toxicity.

Topics: Airway Resistance; Animals; Asbestos; Asbestos, Amphibole; Asbestos, Serpentine; Asbestosis; Bronchial Hyperreactivity; Bronchoalveolar Lavage Fluid; Bronchoconstrictor Agents; Carcinogens; gamma-Glutamyltransferase; Inhalation Exposure; Intubation, Intratracheal; L-Lactate Dehydrogenase; Male; Methacholine Chloride; Rats; Rats, Inbred F344; Respiratory Function Tests; Survival Analysis

Asbestos is associated with South African diamond mines due to the nature of kimberlite and the location of the diamond mines in relation to asbestos deposits. Very little is known about the health risks in the diamond mining industry. The objective of this study was to explore the possibility of asbestos exposure during the process of diamond mining.. Scanning electron microscopy and energy-dispersive X-ray spectroscopy analysis were used to identify asbestos fibres in the lungs of diamond mine workers who had an autopsy for compensation purposes and in the tailings and soils from three South African diamond mines located close to asbestos deposits. The asbestos lung fibre burdens were calculated. We also documented asbestos-related pathological findings in diamond mine workers at autopsy.. Tremolite-actinolite asbestos fibres were identified in the lungs of five men working on diamond mines. Tremolite-actinolite and/or chrysotile asbestos were present in the mine tailings of all three mines. Mesothelioma, asbestosis, and/or pleural plaques were diagnosed in six diamond mine workers at autopsy.. These findings indicate that diamond mine workers are at risk of asbestos exposure and, thus, of developing asbestos-related diseases. South Africa is a mineral-rich country and, when mining one commodity, it is likely that other minerals, including asbestos, will be accidentally mined. Even at low concentrations, asbestos has the potential to cause disease, and mining companies should be aware of the health risk of accidentally mining it. Recording of comprehensive work histories should be mandatory to enable the risk to be quantified in future studies.

Topics: Air Pollutants, Occupational; Asbestos; Asbestos, Amphibole; Asbestosis; Autopsy; Databases as Topic; Diamond; Environmental Monitoring; Epidemiological Monitoring; Female; Humans; Lung; Male; Mesothelioma; Mineral Fibers; Mining; Occupational Exposure; Pleura; Risk Assessment; Soil Pollutants; South Africa; Talc; Workers' Compensation

Topics: Asbestos, Amphibole; Asbestosis; Humans; Male; Middle Aged; Minerals; Pleural Effusion; Silicon Dioxide