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 (222)Rn concentration and dose rates during the Harmattan season (November 2010 to February 2011). The values for the (222)Rn 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 (40)K, (232)Th and (238)U 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).

Public exposure to hazards associated with natural radioactivity in open-pit mining in Ghana.

The results of studies carried out on public exposure contribution from naturally occurring radioactive materials (NORMS) in two open-pit mines in the Western and Ashanti regions of Ghana are reported. The studies were carried out under International Atomic Energy Agency-supported Technical Co-operation Project GHA/9/005. Measurements were made on samples of water, soil, ore, mine tailings and air using gamma spectrometry. Solid-state nuclear track detectors were used for radon concentration measurements. Survey was also carried out to determine the ambient gamma dose rate in the vicinity of the mines and surrounding areas. The effective doses due to external gamma irradiation, ingestion of water and inhalation of radon and ore dusts were calculated for the two mines. The average annual effective dose was found to be 0.30 +/- 0.06 mSv. The result was found to be within the levels published by other countries. The study provides a useful information and data for establishing a comprehensive framework to investigate other mines and develop guidelines for monitoring and control of NORMS in the mining industry and the environment as a whole in Ghana.