Asbestos Fiber Concentrations in the Lungs of Brake Repair Workers: An Updated Analysis Using Several Regression Methods to Handle Nondetectable Measurements

Recent trends in the causation of peritoneal mesothelioma: fiber burden analysis of ten cases

Mesothelioma in the past has been strongly associated with a history of asbestos exposure. Studies have shown that, on average, a higher dose of asbestos exposure is required for the development of peritoneal mesothelioma, and a smaller percentage of cases are asbestos related. Non-asbestos-related causes have been reported, including prior therapeutic radiation, genetic predisposition, and chronic inflammation (e.g. Crohn disease, endometriosis, ventriculo-peritoneal shunts, and diverticulitis). Cases in children have also been reported. Recent studies have shown a decreasing trend in fiber burdens and percentage of asbestos-related mesotheliomas, with similar observations in epidemiological studies. We performed fiber burden analysis on lung tissue in 10 cases (six men, four women) of peritoneal mesothelioma since 2010. Fiber analysis was performed using the sodium hypochlorite digestion technique, with asbestos body concentrations determined by light microscopy. Fiber concentrations and types were determined by scanning electron microscopy. The median age for the six men was 62 years (range: 53-75 years). Three cases were epithelioid type and three were biphasic. Two of six cases (33%) had an elevated lung fiber burden, with one case exclusively crocidolite and the other predominately amosite. The median age for the four women was 55 years (range: 39-63 years). Two cases were epithelioid type and two were biphasic. None of the four had an elevated lung fiber burden. Our findings are consistent with contemporary epidemiological studies indicating that a minority of peritoneal mesotheliomas occurring in men are asbestos related and very few are asbestos related in women.

Talc and mesothelioma: mineral fiber analysis of 65 cases with clinicopathological correlation

Malignant mesothelioma is strongly associated with prior asbestos exposure. Recently there has been interest in the role of talc exposure in the pathogenesis of mesothelioma. We have analyzed lung tissue samples from a large series of malignant mesothelioma patients. Asbestos bodies were counted by light microscopy and mineral fiber concentrations for fibers 5 µm or greater in length were determined by scanning electron microscopy equipped with an energy dispersive spectrometer. The values were compared with 20 previously published controls. Among 609 patients with mesothelioma, talc fibers were detected in 375 (62%) and exceeded our control values in 65 (11%). Elevated talc levels were found in 48/524 men (9.2%) and 17/85 women (20%). Parietal pleural plaques were identified in 30/51 informative cases (59%) and asbestosis in 5/62 informative cases (8%). Commercial amphiboles (amosite and/or crocidolite) were elevated in 52/65 (80%) and noncommercial amphiboles (tremolite, actinolite or anthophyllite) in 41/65 (63%). Both were elevated in 34/65 (52%). Asbestos body counts by light microscopy were elevated in 53/64 informative cases (83%). A history of working in industries associated with asbestos exposure and increased mesothelioma risk was identified in 36/48 cases in men, and a history of exposure as household contacts of an occupationally exposed individual was identified in 12/17 cases in women. We conclude that among patients with mesothelioma, the vast majority have talc levels indistinguishable from background. Of the remaining 11% with elevated talc levels, the vast majority (80%) have elevated levels of commercial amphibole fibers.