Assessment of radioactivity and associated dose from salt mined at lake Gendabi

The natural radioactivity levels in three grades of salt mined from Lake Gendabi were examined to determine the activity concentration and the annual effective dose due to ingestion of 238U, 232Th and 40K radionuclides. The elemental concentration was determined using Energy Dispersive X – ray Fluorescence (EDXRF) and the elemental concentration was converted into the activity concentration. The results indicated an average activity concentration of 43.23 ± 6.08, 8.63 ± 0.75 and 189.20 ± 80.80 Bq/kg for 238U, 232Th and 40K, respectively in grade one salt. The results also indicated an average activity concentration of 238U, 232Th and 40K in grade two salt to be 207.50 ± 20.18, 10.87 ± 2.20 and 574.98 ± 192.65 Bq/kg, respectively. In grade three salt, the results indicated an average activity concentration of 739.93 ± 148.00, 21.30 ± 1.45 and 441.52 ± 118.68 Bq/kg for 238U, 232Th and 40K, respectively. The highest activity concentrations of 238U and 232Th were recorded in grade three salt while the highest activity concentration of 40K was recorded in grade two salt. The total annual ingested effective doses was 0.010 ± 0.001, 0.032 ± 0.003 and 0.086 ± 0.014 mSv in grade one, two and three salts, respectively. The annual effective dose due to ingestion of radionuclides in the salt was below the maximum tolerable limit of 0.29 mSv set by UNSCEAR. Hence, there is no significant radiological hazard connected with intake of the natural radionuclides in the salt from Lake Gendabi.