Evaluation of the carcinogenic risk of granite used in building materials in Zahedan

Abstract Introduction: There are plenty of radioactive elements in the environment.Among these elements, decorative stone which is used in the construction of residential buildings.These rocks include radioactive elements such as uranium and thorium which are used in the buildings for interior and exterior use and can lead to human exposure.so survey of natural radioactivity of the rocks appears to be necessary. Materials and Methods: To determine the carcinogenic risk of 11 types of granite stones used in Zahedan which include, Birjand Granite Quarry, Boroojerd granite, Tooyserkan granite, Zahedan granite, China granite, Nehbandan granite, Mashhad and Yazd granite were selected and determined for Natural radioactivity samples in method of spectroscopy of gamma ray with HPGe detectors. different types of rock from producer were collected and comminuted.for doing Sampling and all the process of the work, the International Atomic Energy Agency guidelines had been followed, such as washing sampling dishes with alcohol and aquapura,, the samples were comminuted and packaged Marynly sealed containers .Marynly dishes for a month to equalize the daughter of uranium and thorium nucleuses in the samples were kept.After samples preparation, the gamma-ray spectrum of each of them were collected for 24 hours by ultra-pure germanium detector(HPGe) .After calibration of the energy of spectrums at the end the specific activity of the radioactive nuclei present in each sample and carcinogenic risk was calculated. Results: Natural radioactivity of samples in terms of Bq / Kg for all samples were calculated then toward assess of risk factors of environment ,the indices such as external risk H ex , Internal risk H in And levels of annual effective radioactivity were measured .The computed Index of H in For samples is between 0.05-1.58 and for H ex Is 0.03-1.31. The annual effective radiation for all samples in the range of mSv / y 0.011-1.12 is placed. Conclusion: External radiation hazard index H ex is Acceptable, less than or equal to 1.For safety in buildings where construction materials are used as indicators of the internal risk H in should be less than one. Internal and external risk for Nehbandan granite and Chinese granite samples have been more than 1so Care should be taken to radioactive rays can be derived from them. According to the Standard UNSCEAR the annual effective radiation dose rate for samples of nehbandan and china granite is more than standard so under the recommendation of the Commission Europe for construction materials, prevention of radiation is necessary. Keywords: Granite, gamma spectrometry, natural radionuclides