Assessment of occupational radiation exposure in underground artisanal gold mines in Tongo, Upper East Region of Ghana

Assessments of radon and gamma radiation levels were carried out in underground artisanal gold mines in Tongo. This is one of the numerous artisanal gold mining communities in Ghana. Solid State Nuclear Track Detectors (SSNTDs) were used to estimate the mean 222Rn concentration and dose rates during the Harmattan season (November 2010 to February 2011). The values for the 222Rn concentration at each monitoring site ranged from 14 ± 4 Bq m−3 to 270 ± 9 Bq m−3, with a mean value of 98 Bq m−3. These measurements are well below the lower action level of 500 Bq m−3 recommended by ICRP for workplaces. The activity concentrations of 40K, 232Th and 238U were determined using gamma-ray spectroscopy method. The effective dose estimates of 0.11 ± 0.02 mSv y−1 to 0.68 ± 0.04 mSv y−1 were below the allowable limit of 20 mSv per annum for occupational exposure control recommended by the ICRP. The total annual effective dose varied from 0.22 ± 0.04 mSv y−1 to 1.92 ± 0.08 mSv y−1.