Endemic malignant mesothelioma: exposure to erionite is more important than genetic factors.

The village of Karain, Turkey, has the world's highest prevalence rate of malignant mesothelioma (MM). Environmental exposure to erionite is thought to cause the disease. However, it has also been suggested that the disease is mainly genetic. Residents in Karain village were traced from 1990 to 2006. Mineral samples were obtained from stones used in construction of their houses and any fibers present were identified. All women who had moved to the village as brides were traced and their cause of death determined. MM was the cause of death in 52 of 322 villagers, representing 50.5% of all deaths. Only 2 of 8 types of stones used in construction contained erionite, and these stones had been used almost exclusively in the mid-sections of the village, where MM was common. In houses not containing erionite, no cases of MM were observed. Sixty-four women came as brides to Karain from villages where erionite or asbestos is not found. Of the 16 women who have died, 11 (69%) died from MM. The extreme risk of MM in Karain is due to indoor exposure to erionite. The effect of genetic factors on mesothelioma development cannot be evaluated in this study, but is likely to be minor.