Radioactivity and dose assessment of marble samples from Igbeti mines, Nigeria.

The concentration and distribution of natural radionuclides in marble around Igbeti marble mines, Nigeria, were measured to evaluate the environmental radioactivity and health effects which the marble samples may posses. The concentration of radionuclides was determined using gamma-ray spectrometry with NaI (Tl) detector. The measured values of the activities of (226)Ra, (232)Th and (40)K in the marble samples were found to lie in the ranges 2.0-2.7, 0.3-1.2 and 5.7-7.3 Bq kg(-1), respectively. The samples were also found to have radium equivalent activity in the range 3.4-4.6 Bq kg(-1), external hazard indices of 0.009-0.012 and internal hazard indices of 0.014-0.019. The estimated representative (I(gammar)) hazard index is 0.028. The measurements show that marble samples from Igbeti mine have low level of natural radioactivity and therefore the use of these types of marble in construction of dwellings is safe for inhabitants.