Possible effect of background radiation on cancer incidence in Chaharmahal and Bakhtiari province.

Background: The induction of cancer appears to be the most important effect of low-dose ionizing radiation to occur in an exposed population. In developing countries 94% of human radiation is from natural sources. In Iran some high altitude regions such as, Chaharmahal & Bakhtiari has high levels of the natural background radiation (higher than the worldwide average). Therefore, investigation of the incidence of cancer relevant to the radiation is very important in this province. Materials and Methods: In this study 751 cases suffering from cancer were investigated according to ICD10 named malignant during 5 years (since 1377 till 1381). 362 cases were selected those suffering from skin, breast, lung, thyroid cancers and leukemia. All data was obtained from health centers and pathological sections of relevant hospitals and statistical test, chi-square, was used for to analyse the data. Results: The result of this study showed that the prevalence of skin, breast, thyroid and lung cancers and leukemia as compared with total recorded cancers was about 20.5%, 7.5%, 2.6%, 1.1% and 16.2%, respectively. From all studied cases 48.3% were male and 51.7% were female. The total radiation induced cancer risk was greater for women than for men. Conclusions: The possibility of skin and thyroid cancers and leukemia is high due to the high levels of the natural background radiation in this province. Iran . J. Radiat. Res., 2003 1(3): 171 - 174