Caspah Kamunda

Background This study assessed the potential health risks from Naturally Occurring Radionuclide Materials (NORMs) in plants collected near a gold mining site in Gauteng Province, South Africa. Methods Eleven plant samples from the mining area and a control site were analyzed using a high-resolution BEGe gamma detector to measure activity concentrations of uranium-238 (²³⁸U), thorium-232 (²³²Th), and potassium-40 (⁴⁰K). Results Plants from the mining area showed slightly higher radionuclide levels (17.4 ± 3.1 Bq/kg for ²³⁸U, 19.7 ± 1.6 Bq/kg for ²³²Th, and 146.7 ± 9.2 Bq/kg for ⁴⁰K) compared with control samples (12.1 ± 1.5, 15.6 ± 1.0, and 125.7 ± 4.8 Bq/kg, respectively). However, all values remained below global averages. The calculated radium equivalent activity (Raeq) was also modest (56.8 ± 4.0 Bq/kg in the mining area vs. 44.1 ± 2.1 Bq/kg in the control area). Estimated radiation exposure indicators—including Annual Effective Dose Equivalent for terrestrial gamma radiation (0.03 mSv/year), ingestion dose (1.24×10⁻³ mSv/year), and external and internal hazard indices (both 0.2)—were all well within internationally accepted safety limits. Conclusion Overall, the radionuclide levels in plants surrounding the mining site pose no significant radiological risk to the public.

Gamma spectroscopy was performed to determine the concentrations of ⁴⁰K, ²²⁶Ra and ²³²Th in maize meal samples collected from shop outlets and open markets in Namibia. The activity concentrations and Excess Lifetime Cancer Risk were determined using a high purity germanium (HPGe) detector. The average activity concentrations of ⁴⁰K, ²²⁶Ra and ²³²Th were found to be 29.98 ± 4.05, 0.99 ± 0.40 and 0.35 ± 0.08 Bq.kg ^{– 1} in the maize meal samples. The result showed the activity concentrations of ⁴⁰K significantly higher than the other radionuclides in all the maize meal samples. The average excess life cancer risk varies from 1.33 x 10 ^{– 13} to 6.05 x 10 ^{– 13} for ⁴⁰K, 8.76 x 10 ^-13 to 1.19 x 10 ^{– 12} for ²³²Th and 2.43 x 10 ^-11 to 2.83 x 10 ^{– 11} for ²²⁶Ra. Hence, when compared with internationally acceptable limits, all values fall within the safety limits. Thus, the study concludes that the maize meals consumed in Namibia are radiologically safe for consumption.

The study evaluates the health risk caused by heavy metals to the inhabitants of a gold mining area. In this study, 56 soil samples from five mine tailings and 17 from two mine villages were collected and analyzed for Asernic (As), Lead (Pb), Mercury (Hg), Cadmium (Cd), Chromium (Cr), Cobalt (Co), Nickel (Ni), Copper (Cu) and Zinc (Zn) using ICP-MS. Measured concentrations of these heavy metals were then used to calculate the health risk for adults and children. Their concentrations were such that Cr > Ni > As > Zn > Cu > Co > Pb > Hg > Cd, with As, Cr and Ni higher than permissible levels. For the adult population, the Hazard Index value for all pathways was found to be 2.13, making non-carcinogenic effects significant to the adult population. For children, the Hazard Index value was 43.80, a value >>1, which poses serious non-carcinogenic effect to children living in the gold mining area. The carcinogenic risk was found to be 1.7 × 10⁻⁴ implying that 1 person in every 5882 adults may be affected. In addition, for children, in every 2725 individuals, 1 child may be affected (3.67 × 10⁻⁴). These carcinogenic risk values were both higher than acceptable values.

Mining is one of the major causes of elevation of naturally-occurring radionuclide material (NORM) concentrations on the Earth’s surface. The aim of this study was to evaluate the human risk associated with exposure to NORMs in soils from mine tailings around a gold mine. A broad-energy germanium detector was used to measure activity concentrations of these NORMs in 66 soil samples (56 from five mine tailings and 10 from the control area). The RESidual RADioactivity (RESRAD) OFFSITE modeling program (version 3.1) was then used to estimate the radiation doses and the cancer morbidity risk of uranium-238 (²³⁸U), thorium-232 (²³²Th), and potassium-40 (⁴⁰K) for a hypothetical resident scenario. According to RESRAD prediction, the maximum total effective dose equivalent (TEDE) during 100 years was found to be 0.0315 mSv/year at year 30, while the maximum total excess cancer morbidity risk for all the pathways was 3.04 × 10⁻⁵ at year 15. The US Environmental Protection Agency considers acceptable for regulatory purposes a cancer risk in the range of 10⁻⁶ to 10⁻⁴. Therefore, results obtained from RESRAD OFFSITE code has shown that the health risk from gold mine tailings is within acceptable levels according to international standards.

Radiological hazards associated with exposure to Naturally Occurring Radionuclides Materials from gold mine tailings in the province of Gauteng in South Africa were evaluated. A comparison was made with soil samples from a control area. In this study, gamma spectroscopy was used to measure the activity concentrations of these radionuclides in 56 soil samples from the mine tailings and 10 soil samples from the control area. The average activity concentrations in Bq∙kg⁻¹ for Uranium-238, Thorium-232, and Potassium-40 from the mine tailings were found to be 785.3 ± 13.7, 43.9 ± 1.0 and 427.0 ± 13.1, respectively. On the other hand, the average activity concentrations in Bq∙kg⁻¹ for Uranium-238, Thorium-232, and Potassium-40 from the control area were found to be 17.0.1 ± 0.4, 22.2 ± 0.5 and 496.8 ± 15.2, respectively. Radiological hazard parameters calculated from these activity concentrations were higher than recommended safe limits. In particular, calculated average values for the external hazard (H_ex) and the internal hazard (H_in) from the mine tailings were found to be 2.4 and 4.5. Both these values were higher than unity, posing a significant health risk to the population in the area.