Natural radioactivity concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰K in commercial building materials and their lifetime cancer risk assessment in dwellers

ABSTRACT

Elevated radioactivity levels of ²²⁶Ra, ²³²Th, and ⁴⁰K in building materials were measured using gamma-ray spectrometry and their associated lifetime cancer risks were also determined. The mean activity concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰K are 45.72 ± 0.55, 65.90 ± 8.89, and 487.32 ± 15.20 Bq kg⁻¹, respectively. Statistically, the principal component (PC) analysis indicates that higher loadings were recorded in Principal Component One (PC1) with large contribution from ²³²Th and ⁴⁰K. The leverage studies indicate that BN Ceramics (BNC) contributes more to the loadings in PC1 followed by Golden Crown Ceramic (GCC) sample. The mean values of 0.399 mSv y⁻¹ do not surpass the world average value of 0.7 mSv y⁻¹. The mean gamma index from the measured samples is 0.644, whereas a mean value of 0.271 for alpha index is noted in the samples. The activity utilization index (AUI) from the samples satisfied the AUI <2, which corresponded with the annual effective dose of <0.3 mSv y⁻¹, except interlock Site 2 and Gomez Spain tiles. Significantly, the mean value of excess lifetime cancer risk of 0.0014 is slightly lower than the world average value of 0.29 × 10⁻³.

KEYWORDS:

• building materials
• radioactivity
• gamma spectroscopy
• excess lifetime cancer risk
• annual effective dose
• alpha index

Acknowledgment

We acknowledge Covenant University management for their encouragement and support to execute this research. We are also thankful to Department of Material Science and Engineering, Obafemi Awolowo, and Ile-Ife for providing full equipment for grinding, crushing, and sieving the building material samples used for this research.

Additional information

Funding

The authors would like to thank the management of Covenant University through Covenant University Center for Research Innovation and Discovery (CUCRID) research grant scheme (No: CUCRID/VC/17/02/02/06-FS) for their 100% financial support of the present study.