Natural Radioactivity in Water and Its Potential Human Health Risk in the Vicinity of Mkuju River Uranium Project in Tanzania

Firmi P Banzi,P Msaki ,Najat K Mohammed

doi:10.11648/j.ijepp.20160405.11

Abstract

Consistent with best practices in uranium mining, the collection and use of site characterisation data are indispensable to ensure compliance with regulations. To comply with this requirement, two samples from each of the 47 locations were collected in an area of about 1300 km2 in the vicinity and concession area of the Mkuju River Project. The samples were analysed for radioactivity using alpha spectrometry. The activity concentrations were used to estimate health risks attributable to the consumption of drinking water containing radionuclides. The range of activity concentrations (mBqL-1) were much higher in groundwater collected from the concession area for 238U (79.89 to 87.06), 234U (79.44 to 88.38), 226Ra (41.61 to 59.07), 232Th (5.32 to 9.41), and 228Ra (3.98 to 8.59) than in groundwater for 238U (20.61 to 47.21), 234U (21.70 to 49.10), 226Ra (16.80 to 43.45), 232Th (0.12 to 2.80), and 228Ra (0.10 to 2.43), and surface water for 238U (17.33 to 27.24), 234U (21.06 to 34.43), 226Ra (15.00 to 25.61), 232Th (0.16 to 2.10), and 228Ra (0.12 to 1.99) collected in the vicinity of the project. The calculated annual effective doses and carcinogenic risks resulting from the activity concentrations in drinking water were relatively marginal, since the activity concentrations were lower than the WHO permissible limits for drinking water. These findings suggest that the water resources at MRP are safe. Thus, since this study was conducted before mining activities, these data can be used as a baseline for monitoring potential future water pollution around the Mkuju River Project.

Highlights

The presence of radionuclides of natural origin in pristine water is of little radiological concern to a local population compared to the potential for anthropogenic radionuclide concentrations added to water sources from sources such as mineral extraction [1], emissions from the nuclear industry [26], oil and natural gas production [7], combustion of coal and other fuels [8], and use of phosphate fertilizer in farming [911]
This observation implies that the release of 232Th series from a uranium mineralised zone due to uranium mining activities will have less of an impact on water pollution than 238U
The activity concentrations in water samples from the Mkuju River Project (MRP) concession area were found to be higher in groundwater than in surface water

Summary

Introduction

The presence of radionuclides of natural origin in pristine water is of little radiological concern to a local population compared to the potential for anthropogenic radionuclide concentrations added to water sources from sources such as mineral extraction [1], emissions from the nuclear industry [26], oil and natural gas production [7], combustion of coal and other fuels [8], and use of phosphate fertilizer in farming [911]. As a result of their long half-lives and solubility in water, 238U, 234U, 228Ra, 226Ra, 222Rn, 210Po, and 232Th are the main radionuclides from the 238U and 232Th decay series, in addition to 235U, that contribute to the activity concentrations in water bodies and the associated risk to biological systems that are exposed to the water [12,13]. To ensure that the radiological risks associated with increased radioactivity in water caused by uranium mining are assessed and that the risk is minimised according to international safety standards [14,15], uranium-producing countries have enacted regulations to address three key issues: (i) minimisation of public concerns about potential water pollution during and after the mining operations, (ii) effective intervention to restrict discharge of radionuclides to ground or surface water, and (iii) effective means to verify compliance with regulatory limits. In line with the above initiatives, drinking water quality in

Methods

Results

Conclusion