External gamma-radiation dose to Syrian population based on the measurement of gamma-emitters in soils

External gamma-radiation dose due to the presence of natural radionuclides and man made radionuclide Cs-137 in soils has been determined. A total of 109 representative surface soil samples and 38 core samples were collected from all over the Syrian Lands and analyzed for radioactivity during the 2000 - 2003 period. Activity concentration levels of naturally occurring radionuclides Th-232, U-238, (226) Ra 40K, and man made radionuclide Cs-137 in various types of Syrian soils were found to be in the range of 3 - 50 Bq(.)kg(-1), 6 - 69 Bq(.)kg(-1), 4 - 80 Bq.kg(-1), 85 - 735 Bq.kg(-1), and 1.2 - 143 Bq.kg(-1), respectively. The annual effective dose for the whole Syrian population due to natural radionuclides was estimated and found to be in the range of 10 - 123 mu Sv.y(-1), with an overall mean value of 52 mu Sv(.)y(-1) and a standard deviation of 19 mu Sv.y(-1), while an additional dose of 4 mu Sv.y(-1) for man-made radionuclide Cs-137 was also estimated. The obtained data is also compared with previously reported values of radiation dose for the Syrian population 659 mu Sv.y(-1), which was determined by using TL dosimeters.