To examine the incidence and epidemiology of malignant mesothelioma in immigrants from Karain where there is an extraordinarily high incidence of mesothelioma, Cappadocia, Turkey, to Stockholm, Sweden, and their children over 20 years of age born in Stockholm, i.e. two genetically similar populations with and without erionite exposure.

This survey was conducted as a retrospective cohort study. Standardized average annual mesothelioma incidence rates (AAMIRs) and mesothelioma standardized incidence ratio (mSIR) were calculated. Cox regression analysis was used to determine the importance of different factors related to mesothelioma risk.

The cohort consisted of 337 people, 203 of whom were born and/or lived in Karain before immigrating to Sweden (erionite-exposed), and 134 who were born in Stockholm (erionite-unexposed). There were 69 deaths, 42 (61%) due to mesothelioma, and two patients with the disease who were still alive. Of these 44 patients, 22 were men. All mesothelioma patients were in the erionite-exposed group. In the age group 30–49 years, mesothelioma developed in 11 of 38 (29%) with erionite exposure, while there were no cases among 86 persons in the non-exposed group. For men, the AAMIR was 253.9 per 100,000 persons in the whole cohort, and for women, it was 350.9. The mSIR was 71.9 for men and 393.1 for women. Exposure to erionite exceeding 20 years and age over 40 years were associated with increased mesothelioma risk.

Exposure to erionite is the leading cause of mesothelioma in Karain villagers, and genetic factors are probably of minor importance.