<prompt> Mesothelioma is most commonly caused by?AsbestosisSilicosisAnthracosisCoal workers pneumoconiosis  <response>: Ans. a AsbestosisRef: Harrison 19th ed. 1689 Working with asbestos is the most common risk factor for mesothelioma. Indeed, the relationship between asbestos and mesothelioma is so strong that many consider mesothelioma a signal or sentinel tumor. In rare cases, mesothelioma has also been associated with irradiation of the chest or abdomen, intrapleural thorium dioxide thorotrast as a contrast medium, and inhalation of other fibrous silicates, such as erionite. 