ASBESTOS GROUPS AND ERIONITE SERIES MINERALS

The term asbestos is an industrial term that refers to a group of minerals including the amphibole group minerals tremolite, actinolite, anthophyllite, amosite (cummingtonite-grunerite series), crocidolite (riebeckite) and the serpentine group mineral chrysotile. In the 1950s, asbestos was used extensively in a wide range of industries. Malignant pleural mesothelioma is a relatively rare form of a lung cancer in which thick layers of malignant cancer develop on the outer lining of the lung. Regardless of the source of exposure (occupational or environmental), the majority of patients dies within 9 to 18 months of diagnosis and current therapy is not satisfactory. Today, the use of “regulatory” asbestos group minerals has been banned in many countries; however, some “non-regulatory” asbestos group minerals have been reported - they are also a human health hazard but are not officially banned. Until 1959, erionite, a zeolite group mineral, was thought to be a rare mineral, when vast erionite deposits were found in the western US. In the 1970’s, erionite fibers were first observed in the lung tissues of mesothelioma cases from three villages - Karain, Sarihidir, Tuzkoy - in the Cappadocia region of Turkey, where there was an extremely high level of mortality (>50%) from malignant mesothelioma. In 1987, the International Agency for Research on Cancer reported that there was sufficient evidence for carcinogenicity of erionite in animal and cell experiments and listed it as a Group-I carcinogen. In 1997, erionite was elevated to a series status and individual species of erionite-Na, -K, -Ca were defined. In 2008, erionite characterization guidelines and a modified balance error (E%) formula with the boundary conditions of +/- 10 % wt along with the Mg-test (Mg<0.80) was proposed for a “positive” identification of erionite series minerals. Using these criteria, published data were re-evaluated and re-classified as erionite-Na, -K, -Ca and a new mean chemical formula was proposed. If data do not pass the E% and Mg-tests, then any reference to them in the literature is proposed to be disregarded. Several countries including the US and Mexico have vast reserves of zeolite deposits including erionite. Only one mesothelioma case has been reported in the US and one in Mexico, but erionite is found in many locations.