The causes and mechanisms of the disease are still not well understood and may be related to the following factors: 1. Long-term exposure to asbestos All types of asbestos fibers are almost always related to the pathogenesis of mesothelioma, but the risk of each fiber is not the same; the most dangerous is exposure to crocidolite and the least dangerous is exposure to yellow asbestos. The latency period between the first exposure to asbestos and the onset of the disease is generally 20-40 years, and the incidence of mesothelioma is proportional to the duration and severity of exposure. Evidence that asbestos causes pleural mesothelioma: (1) animal experiments on asbestos fluid can induce pleural mesothelioma; (2) asbestos fibers are found in malignant mesothelioma; (3) asbestos workers, especially those who have worked for 20-40 years, are found to have a 3.1% incidence of mesothelioma at autopsy. 2. Other non-asbestos causes Exposure to natural mineral fibers, chronic infection of the pleural cavity (tuberculous pleurisy), and recurrent pulmonary infections. Cases of pleural mesothelioma caused by exposure to radiation have also been reported, and the time from exposure to radiation to the discovery of pleural mesothelioma ranged from 7-36 years, with an average of 16 years. 3. Sarcoidosis 40SV40 (infection) may be associated with SV40 infection in 30%-50% of patients with no history of asbestos exposure. Millions of Americans during the polio epidemic years may have been infected with SV40 as a result of Salk vaccination. recently, SV40 was isolated in patients with brain tumors and mesothelioma. carbone and colleagues isolated SV40 fragments in 60% of mesothelioma patients and successfully induced mesothelioma in rats after intrathoracic administration of SV40.