for thermal water and in the range 0.11-38.8 Sv·y 1 for mineral water. Measurement of activity concentrations of natural radionuclides in the examined samples was carried out with a gamma-spectrometer with high-purity germanium (HPGe) detector, having a relative effi ciency of 70%.

Investigations of natural radioactivity in water, air, and soil are conducted frequently and routinely. Exposure to high concentrations of natural radioactive radon gas can cause irradiation of respiratory organs, which can lead to lung cancer. This paper presents measurements of radon activity concentrations in dug wells and natural springs of the Tuzla area (Bosnia and Herzegovina), which ranged from 214 to 3702 mBq L -1. Our results have shown that the radon activity concentration did not exceed the EU reference level for radon in drinking water (100 Bq L -1 ).

The results of the specific activities of232Th,226Ra and40K measured in samples of commonly used building materials in Bosnia and Herzegovina are presented. Measurements were performed by gamma-ray spectrometer with coaxial HPGe detector. The surface radon exhalation and mass exhalation rates for selected building materials were also measured. The determined values of specific activities were in range from 3.16±0.81 Bq kg−1to 64.79±6.16 Bq kg−1for232Th, from 2.46±0.95 Bq kg−1to 53.89 ±3.67 Bq kg−1for226Ra and from 28.44±7.28 Bq kg−1to 557.30±93.38 Bq kg−1for40K. The radium equivalent activity, the activity concentration index, the external and internal hazard indices as well as the absorbed dose rate in indoor air and the corresponding annual effective dose, due to gamma-ray emission from the radioactive nuclides in the building material, were evaluated in order to assess the radiation hazards for people. The measured specific activities of the natural radioactive nuclides in all investigated building materials were compared with the published results for building materials from other European countries. It can be noted that the results from this study are similar to the data for building materials from neighbouring countries and for building materials used in the EU Member States. The radiological hazard parameters of the building materials were all within the recommended limits for safety use.

The results of activity concentration measurements of natural occurring radioactive nuclides (238)U, (235)U, (232)Th, (226)Ra, and (40)K in surface soil samples collected in the area of cities Tuzla and Lukavac, northeast region of Bosnia and Herzegovina were presented. Soil sampling was conducted at the localities that are situated in the vicinity of industrial zones of these cities. The measured activity was in the range from (8 ± 4) to (95 ± 28) Bq kg(-1) for (238)U, from (0.41 ± 0.06) to (4.6 ± 0.7) Bq kg(-1) for (235)U, from (7 ± 1) to (66 ± 7) Bq kg(-1) for (232)Th, from (6 ± 1) to (55 ± 6) Bq kg(-1) for (226)Ra, and from (83 ± 12) to (546 ± 55) Bq kg(-1) for (40)K. In order to evaluate the radiological hazard of the natural radioactivity for people living near industrial zones, the absorbed dose rate, the annual effective dose and the radium equivalent activity have been calculated and compared with the internationally approved values.

Radon is a colorless, odorless, radioactive gas. It is formed naturally from the decay of radioactive elements, such as uranium, which are found in different amounts in soil and rock throughout the world. Radon gas in the soil and rock can move into the air and into underground water and surface water. In this paper the results of measurements of radon activity concentration in drinking water from drilled wells in Tuzla City, Bosnia and Herzegovina are presented. The obtained results of radon activity concentration in drinking water samples ranged from 182 mBqL -1 to 2368 mBqL -1 which does not exceed the value of 11.1 BqL -1 recommended by the Environmental Protection Agency for drinking water. The measurements of radon activity concentration were conducted with AlphaGUARD and AquaKIT equipment (Genitron Instruments).