The prevailing model of radiation-induced cancer posits that the risk rises linearly with dose at a rate of 5% per Sv. If this linear no-threshold model is correct, it should be possible to observe an increased incidence of cancer in Ramsar through careful long-term studies currently underway. Early anecdotal evidence from local doctors and preliminary cytogenetic studies suggested that there may be no such harmful effect, and possibly even a radioadaptive effect. More recent epidemiological data show a slightly reduced lung cancer rate and non-significantly elevated morbidity, but the small size of the population (only 1800 inhabitants in the high-background areas) will require a longer monitoring period to draw definitive conclusions. Furthermore, there are questions regarding possible non-cancer effects of the radiation background. An Iranian study has shown that people in the area have a significantly higher expression of CD69 gene and also a higher incidence of stable and unstable chromosomal aberrations. Chromosomal aberrations have been found in other studies and a possible elevation of female infertility has been reported.