The Association between the Histological Subtypes of Mesothelioma and Asbestos Exposure Characteristics.

Asbestos mining operations have left South Africa with a legacy of asbestos contamination and asbestos-related diseases continue to be a problem. The large-scale mining of three types of asbestos presents a unique opportunity to study malignant mesothelioma of the pleura (mesothelioma) in South Africa. This study aimed to describe the demographics of deceased individuals diagnosed with mesothelioma and explore any associations between the histological morphology of mesothelioma and asbestos characteristics. We reviewed the records of all deceased miners and ex-miners from the Pathology Automation System (PATHAUT) database of the National Institute of Occupational Health (NIOH) that were histologically diagnosed with mesothelioma in the period from January 2006-December 2016 (11 years). The study population does not include all cases of mesothelioma in South Africa but rather those that reached the compensation system. Crocidolite asbestos fibres were identified in the majority of mesothelioma cases (n = 140; 53.4%). The epithelioid subtype was most commonly present in both occupational and environmental cases. Cases with the sarcomatous subtype were older at death and fewer female cases were diagnosed with this subtype. No relationship between mesothelioma subtype and asbestos type or asbestos burden or fibre size was established.

The significance of non-occupational asbestos exposure in women with mesothelioma.

Malignant mesothelioma is a rare and aggressive pleural or peritoneal tumour almost always caused by exposure to asbestos fibres. Exposure to asbestos can cause malignant mesothelioma 30-40 years after exposure. A description of sources of exposure is important for prevention and possible financial compensation. Three women with cases of histologically confirmed malignant mesothelioma diagnosed from non-occupational asbestos exposure are described. Patients were contacted for an interview to assess their exposure history to asbestos. All three cases had mixed exposure histories related to secondary, environmental contamination, and domestic exposure. This case series highlight how ubiquitous asbestos is in the environment and how diverse the exposures may be. It is anticipated that a significant number of cases of non-occupational mesothelioma will be seen in many countries for several decades given the extent of asbestos containing materials.

The risk of asbestos exposure in South African diamond mine workers.

OBJECTIVES: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Malignant mesothelioma in a patient with anthophyllite asbestos fibres in the lungs.

The amphibole asbestos, anthophyllite, is associated with asbestos-related disease in humans, along with mesothelioma in animal models. In humans, however, there are only three cases of histologically proven malignant mesothelioma of the pleura associated with anthophyllite that have been documented in the English-language literature. A fourth case is presented in a man who lived in South Africa and had anthophyllite in his lung. Anthophyllite was never commercially mined in South Africa. Using scanning electron microscopy, his lung fibre burden was calculated to be 358,000 fibres and 31,000 asbestos bodies per gram of dry weight of lung tissue. The mean aspect ratio of the anthophyllite fibres in the lung was 41.2 (SD = 28.8). No other types of asbestos were detected in the lung. His exposure was almost certainly occupational. He worked in the plastic manufacturing industry and was exposed to talc and asbestos blankets that were used to insulate machinery.

Mica dust as a cause of severe pneumoconiosis.

BACKGROUND: Mica exposure is frequent in mines, mills, agriculture, construction, and industry. This is a case report of possible mica pneumoconiosis. METHODS: Case report and description of pathology. Histology slides were subjected to spectroscopic examination. RESULTS: Fibrosis in the presence of mica, without evidence of silica was confirmed. CONCLUSIONS: This report indicates that mica exposure may result in mica pneumoconiosis.