Granite rocks as a source of natural radioactivity: health risk implications

This paper was carried out for calculations of the radiological hazard factors and ⁴⁰ K, ²³²Th, and ²²⁶Ra activity concentrations in granite rocks in the Zagros Mountain series district in the Kurdistan region, Iraq. A high-purity germanium detector was utilized to monitor the activity concentrations for 45 granite samples. The samples were also chemically analyzed using inductively coupled plasma optical emission spectrometer (ICP-OES) and X-ray fluorescence spectroscopy (XRF). The average activity concentration of ²²⁶Ra is 84.06 ± 4.57 Bq/kg, with a range of 56.39-131.83 Bq/kg, and for ²³²Th is found to be 37.35 ± 1.54 Bq/kg, with a range of 23.64-54.50 Bq/kg. The activity concentration range of ⁴⁰ K is between 371.10 and 1083.80 Bq/kg, with an average of 528.71 ± 8.51 Bq/kg. Natural levels of radionuclides are above international limits. The radiological hazard parameters of gamma index (1.29), the excess lifetime cancer risk for outdoor (0.36 × 10^-3) and indoor (2.77 10^-3), the annual effective dose for indoor (0.79 mSv/y) and outdoor (0.1 mSv/y), and the external (83.44 nGy/h) and internal (161.44 nGy/h) absorbed dose rates are all higher than the international limit. The other radiological parameters (e.g., radium equivalent and alpha index) were within international limitation values. The composition of granite samples was determined using the XRF and ICP-OES techniques. Both methods demonstrated greater uranium concentrations and enriched trace elements. Multi-statistical analyses are employed to uncover and comprehend the correlation relations between the natural activity concentrations and also between the radiological hazard parameters.