Case-fatality study of workers and residents with radiographic asbestos disease in Libby, Montana.

BACKGROUND: Vermiculite ore from Libby, Montana contains on average 24% of a mixture of toxic and carcinogenic amphibole asbestiform fibers. These comprise primarily winchite (84%), with smaller quantities of richterite (11%) and tremolite (6%), which are together referred to as Libby amphibole (LA). METHODS: A total of 1883 individuals who were occupationally and/or environmentally exposed to LA and were diagnosed with asbestos-related pleuropulmonary disease (ARPPD) following participation in communitywide screening programs supported by the Agency for Toxic Substances and Disease Registry (ATSDR) and followed up at the Center for Asbestos Related Disease (CARD) between 2000 and 2010. There were 203 deaths of patients with sufficient records and radiographs. Best clinical and radiologic evidence was used to determine the cause of death, which was compared with death certificates. RESULTS: Asbestos-related mortality was 55% (n = 112) in this series of 203 patients. Of the 203 deaths, 34 (17%) were from asbestos-related malignancy, 75 (37%) were from parenchymal asbestosis, often with pleural fibrosis, and 3 (1.5%) were from respiratory failure secondary to pleural thickening. CONCLUSIONS: Asbestos is the leading cause of mortality following both occupational and nonoccupational exposure to LA in those with asbestos-related disease.

Rapid progression of pleural disease due to exposure to Libby amphibole: "Not your grandfather's asbestos related disease".

BACKGROUND: Residents and mine employees from Libby, Montana, have been exposed to asbestiform amphiboles from the vermiculite mine that operated in this location from the mid-1920s until 1990. Clinical observations show a different form of asbestos-related toxicity than other forms of asbestos. METHODS: Five illustrative cases from the Center for Asbestos-Related Diseases in Libby were selected. All had clear exposure histories, multiple follow-up visits, illustrative chest radiographic studies, serial pulmonary function tests, and sufficient length of follow-up to characterize disease progression. RESULTS: These cases developed increasing symptoms of dyspnea and chest pain, progressive radiological changes that were predominantly pleural, and a restrictive pattern of impaired spirometry that rapidly progressed with significant loss of pulmonary function. CONCLUSIONS: LA exposure can cause a non-malignant pleural disease that is more rapidly progressive and more severe than the usual asbestos-related disease.

Environmental exposure to Libby Asbestos and mesotheliomas.

BACKGROUND: Thirty-one cases of mesothelioma resulting from exposure to Libby Asbestos have been identified from Libby, Montana. Eleven cases not previously reported are the subject of this report. METHODS: These cases are in non-occupationally exposed people, appearing to have resulted from exposure to contamination of the community, the surrounding forested area, and areas in proximity to the Kootenai river and railroad tracks used to haul vermiculite. RESULTS: These exposures are considered to be of a low degree of magnitude, but are similar to those in Western Australia's crocidolite mine at Wittenoom Gorge. An epidemic of mesothelioma can likely be expected from this type of asbestos contamination over the next 20 plus years.

Asbestos-related pleural disease due to tremolite associated with progressive loss of lung function: serial observations in 123 miners, family members, and residents of Libby, Montana.

BACKGROUND: The community of Libby, Montana has recently been the focus of national attention secondary to widespread amphibole contamination associated with vermiculite mining and processing. METHODS: Patients who had occupational and non-occupational exposure to amphibole asbestos in Libby, Montana were evaluated for progressive loss of pulmonary function. RESULTS: Of the 123 patients evaluated, 94 demonstrated average age-corrected accelerated loss per year of vital capacity at 3.2%, total lung capacity (TLC) 2.3%, and DLCO 3.3%. All patients all had predominantly pleural changes with minimal to no interstitial disease. CONCLUSIONS: The study demonstrates a progressive loss of pulmonary function in patients exposed to tremolite asbestos.