GUIDELINES FOR "POSITIVE" IDENTIFICATION OF ERIONITE SERIES MINERALS BEFORE TOXICITY TESTS

In 1987, the International Agency for Research on Cancer (IARC) reported that there was sufficient evidence for carcinogenicity of erionite in experimental animals and listed it as a Group-I carcinogen. Erionite fibers were observed in the lung tissues of mesothelioma cases from three villages - Karain, Sarihidir, Tuzkoy - of the Cappadocia region of Turkey, where there was an extremely high level of mortality (>50%) from malignant mesothelioma. In 1997, erionite was elevated to series status and individual species of erionite-Na, -K, -Ca have been 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 for erionite series minerals. Using these criteria, published data was re-evaluated and re-classified as erionite-Na, -K, -Ca and a new mean chemical formula was proposed. In 2011, the Report on Carcinogens, stated that “erionite is known to be a human carcinogen based on sufficient evidence of carcinogenicity from studies in humans”. International Zeolite Association Commission on Natural Zeolites stated that ”Compared to other mineral particles, erionite has been shown to have greater pathogenicity than asbestos. Therefore, erionite-bearing sedimentary rock should not be used for any purpose unless it is totally and effectively controlled to prevent exposures during mining, processing, handling, and utilizing the materials, to humans as well as animals”. In the past, there have been biological experiments performed using uncharacterized erionite specimens. Recently, few cases of mesothelioma due to erionite is started reporting elsewhere other than in Turkey. To understand the mechanism of toxicity of erionite series minerals, animal and cell experiments should be performed only with minerals that have passed the quantitative characterization tests of both E% and Mg-content. Regulatory Agencies should ensure that the proposed guidelines for “positive” identification of erionite series minerals, both for a single fiber and a bulk mineral, are followed closely. International data bank should be established at one of the mineralogical societies and new data must be evaluated rigorously before being accepted and included.