Malignant mesothelioma in the western world is often associated with
asbestos exposure. It is a relatively rare
cancer that causes approximately 2,500 deaths yearly in the United States and 1,000 deaths yearly in the United Kingdom. In contrast, among people born in the Cappadocian (Turkey) villages of Tuzkoy, Karain, and "Old" Sarihidir, approximately 50% of deaths are caused by
malignant mesothelioma. This epidemic has been attributed to
erionite exposure, a type of fibrous
zeolite mineral commonly found in this area of Turkey. In these three villages,
malignant mesothelioma occurs in certain houses but not in others. The hypothesis was that a unique and more carcinogenic
erionite was present in certain houses and caused
malignant mesothelioma. We determined the X-ray diffraction pattern and the crystal structure of
erionite from
malignant mesothelioma villages and compared the results with the
erionite samples from nearby non-
malignant mesothelioma villages and from the United States. We found the same type of
erionite in Cappadocian villages, with or without a
malignant mesothelioma epidemic, in households with high or no incidence of
malignant mesothelioma and in the United States. Pedigree studies of the three
malignant mesothelioma villages showed that
malignant mesothelioma was prevalent in certain families but not in others. When high-risk
malignant mesothelioma family members married into families with no history of it,
malignant mesothelioma appeared in the descendants. Genetically predisposed family members born and raised outside the
malignant mesothelioma villages did not seem to develop
malignant mesothelioma. In summary, pedigree and mineralogical studies indicate that the
malignant mesothelioma epidemic is caused by
erionite exposure in genetically predisposed individuals. This is the first time that genetics is shown to influence
mineral fiber carcinogenesis.