Radiological risk assessment of cement used in contemporary South African buildings

Abstract

Using a calibrated NaI(TI) and a well-shielded detector connected to a computer-resident quantum multichannel analyser, the radionuclide contents of primordial radionuclides (²²⁶Ra, ²³²Th and ⁴⁰K) were evaluated in commonly used cement brands in South Africa, and the associated radiation risk parameters were calculated. The reported activity concentrations varied from 8.00 ± 2.83 to 45.00 ± 2.79 Bq/kg, 12.00 ± 0.90 to 32.00 ± 0.51 Bq/kg and 454.00 ± 0.56 to 1765.00 ± 0.93 Bq/kg for ²²⁶Ra, ²³²Th and ⁴⁰K, respectively. The absorbed gamma dose rate, annual effective dose equivalent, annual gonadal dose equivalent, excess lifetime cancer risk, gamma index and alpha index were utilised as the radiological health impact metrics to evaluate the potential radiation risks. The determined radiological health impact parameter results were below the relevant radiation safety authorities’ recommended reference levels for building materials. Therefore, the use of cement products as building materials presents no significant risk in the study areas.

Significance:

The results of this study contribute to understanding the radiological risks associated with different brands of commonly used cement in South Africa and provide fundamental data for the activity concentrations of primordial radionuclides ²²⁶Ra, ²³²Th and ⁴⁰K. These studies have been instructive from a building materials radiation safety viewpoint and reveal that the assessed risk parameters fall within the recommended safety limits. This is significant from the perspective of environmental health and radiological protection concerning the safe use of the studied cement. The methodology and findings can also inform similar studies in other regions, enhancing global awareness of material safety standards.