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Asbestos and zeolites are silicate-based minerals, linked inextricably via paradoxical similarities and differences which have emanated from different geological epochs. Both have been employed in the service of humanity through millennia: asbestos, for its "inextinguishable" quality of being an insulator against heat and fire; zeolite, a "boiling stone" with its volcanic and marine sedimentary rock origins, for its propensity to adsorb water and remove metals and toxins. Serious adverse health effects observed in asbestos miners as long ago as the 1st Century AD did not halt the rising popularity of asbestos. As the miracle material of the 1900s, asbestos production and consumption exploded, culminating in its ubiquity in ships, vehicles, homes, commercial buildings, and over 3000 different industrial and household products. Through the 1940s and 1950s, epidemiological studies concluded that asbestos was a likely cause of asbestosis, lung cancer, and malignant mesothelioma, and it is now banned in many but far from all countries. The long latency between exposure to asbestos and the occurrence of cancer has obscured the deadly consequences of asbestos exposure for centuries. Even today, a considerable part of the world population is insufficiently aware of the dangers of asbestos, and millions of tons of this carcinogen continue to be mined and used worldwide. Zeolites, both natural and synthetic, are microporous aluminosilicate minerals commonly used in a myriad of processes, in the petrochemical industry, in domestic appliances and cleaning agents, as commercial adsorbents and exchangers for toxins and pollutants, and as catalysts. Zeolites are found in agriculture, veterinary science, and human health. More recently, new materials such as carbon nanotubes are being employed in materials requiring durability and thermal and electrical conductivity, yet nanotubes are now joining the ranks of more established particulates such as asbestos and silica, in causing human disease. In this review, we compare and contrast the similarities and differences of these two groups of silicate minerals and their waxing and waning use in the employ of humanity.

This review analytically examines the published data for erionite-related malignant pleural mesothelioma (E-MPM) and any data to support a genetically predisposed mechanism to erionite fiber carcinogenesis. Adult patients of age ≥18 years with erionite-related pleural diseases and genetically predisposed mechanisms to erionite carcinogenesis were included, while exclusion criteria included asbestos- or tremolite-related pleural diseases. The search was limited to human studies though not limited to a specific timeframe. A total of 33 studies (31042 patients) including 22 retrospective studies, 6 prospective studies, and 5 case reports were reviewed. E-MPM developed in some subjects with high exposures to erionite, though not all. Chest CT was more reliable in detecting various pleural changes in E-MPM than chest X-ray, and pleural effusion was the most common finding in E-MPM cases, by both tests. Bronchoalveolar lavage remains a reliable and relatively less invasive technique. Chemotherapy with cisplatin and mitomycin can be administered either alone or following surgery. Erionite has been the culprit of numerous malignant mesothelioma cases in Europe and even in North America. Erionite has a higher degree of carcinogenicity with possible genetic transmission of erionite susceptibility in an autosomal dominant fashion. Therapeutic management for E-MPM remains very limited, and cure of the disease is extremely rare.

Malignant mesothelioma is an aggressive malignancy related to asbestos and erionite exposure. AP-1 transcriptional activity and the NF-κB signaling pathway have been linked to mesothelial cell transformation and tumor progression. HGF and c-Met are highly expressed in mesotheliomas. Phosphoinositide 3-kinase, AKT, and the downstream mTOR are involved in cell growth and survival, and they are often found to be activated in mesothelioma. p16(INK4a) and p14(ARF) are frequently inactivated in human mesothelioma, and ∼50% of mesotheliomas contain the NF2 mutation. Molecular therapies aimed at interfering with these pathways have not improved the dismal prognosis of mesothelioma, except possibly for a small subset of patients who benefit from certain therapies. Recent studies have shown the importance of asbestos-induced inflammation in the initiation and growth of mesothelioma, and HMGB1 and Nalp3 inflammasome have been identified as key initiators of this process. Asbestos induces cell necrosis, causing the release of HMGB1, which in turn may activate Nalp3 inflammasome, a process that is enhanced by asbestos-induced production of reactive oxygen species. HMGB1 and Nalp3 induce proinflammatory responses and lead to interleukin-1β and TNF-α secretion and NF-κB activity, thereby promoting cell survival and tumor growth. Novel strategies that interfere with asbestos- and erionite-mediated inflammation might prevent or delay the onset of mesothelioma in high-risk cohorts, including genetically predisposed individuals, and/or inhibit tumor growth. The very recent discovery that germline BAP1 mutations cause a new cancer syndrome characterized by mesothelioma, uveal melanoma, and melanocytic tumors provides researchers with a novel target for prevention and early detection.

Both asbestos and erionite related malignant pleural mesothelioma (MPM) is a serious health problem in Turkey. Erionite has a higher potency in the lung than asbestos and familial clustering of malignant mesothelioma suggests a genetic predisposition to this cancer among affected individuals. Neither Simian virus 40 (SV40) nor human herpes virus 8 (HHV-8) are co-factors in the pathenogenesis of environmentally induced mesothelioma. A survival advantage has been demonstrated in patients with asbestos-induced mesothelioma compared with erionite-induced mesothelioma. This together with the proliferation index (PI) can be used as an independent prognostic factor for patients with malignant pleural mesothelioma. It is envisaged that the application of these prognostic approaches together with the new TNM staging system will allow investigations to be more precisely carried out and evaluated.

Asbestos deposits have been used locally by the rural inhabitants of Central and Southeastern Anatolia for domestic purposes for many years. Mineralogical analysis revealed that tremolite is the most prominent asbestos type found in the region. There is in addition another mineral fiber found particularly in three villages located in the Cappadocian region of Central Anatolia (zeolite villages). This is a non-asbestos mineral, which has been identified as the fibrous zeolite, erionite. This fiber is present in the volcanic tuffs, which are used as building stone. Hence, exposure to erionite fibers is always possible in the houses, annexes, and streets of the villages. It has been demonstrated that both asbestos and erionite cause a variety of benign and malignant chest diseases. Among the diseases, calcified pleural plaques (CPP) are the most frequently seen and may be used as an indicator of mineral fiber exposure. Asbestos and erionite exposure are the main causes of malignant mesotheliomas in Turkey. In zeolite villages malignant mesothelioma is responsible for more than 50% of the total deaths. A recent study showed that simian virus 40 is not a cofactor in the pathogenesis of environmental malignant mesothelioma in Turkey. An additional recent genetic-epidemiological study showed that there are some families, which are genetically predisposed to mesothelioma.

Objective: The aim of the present study was to evaluate the pericardial involvement in patients with malignant mesothelioma caused by exposure to different minerals., Methodology: Forty-two patients (mean age of 52 +/- 12 years) with malignant mesothelioma were examined with transthoracic echocardiography. Thirty-three (78.9%) patients had a history of environmental exposure to asbestos and nine (21.4%) had a history of environmental exposure to erionite., Results: In 19 (45.2%) patients with malignant pericardial mesothelioma, pericardial involvement was determined by echocardiography. The other 23 (54.8%) patients had no pericardial involvement. Pericardial effusion was detected in nine (64.3%) patients and pericardial effusion was small in six (14.3%) patients, moderate in one (2.4%) patient and large in two patients. Thickening of the pericardium was observed in eight (19%) patients. In another two (7.1%) patients pericardial calcification was observed. Among the 33 patients who had been exposed to asbestos, 15 (45.5%) had pericardial involvement, and among the nine patients with a history of exposure to erionite, four (44.4%) had pericardial involvement. There was no difference in terms of pericardial involvement in different stages of the tumour (P > 0.05)., Conclusions: Pericardial involvement is commonly seen in patients with malignant mesothelioma. Among patients exposed to asbestos or zeolite there was no difference in terms of pericardial involvement. Furthermore, pericardial involvement was not related with the stage of the tumour.