Assessment of natural radioactivity in mango, the influence of soil radioactivity, its radiation hazard indices and the overall excess lifetime cancer risk

Abstract

Background : Radionuclide ingestion has raised a global concern due to its radiological implication on man. Materials and Methods : Activity concentration of natural radionuclides ( 226 Ra, 232 Th and 40 K) in soil, leaf and fruit samples of mango plants from Akure, Nigeria has been estimated using gamma ray spectrometer NaI (Tl) detector. Spectra analyses were performed with the Genie2K spectrometry software, version 2.1 (Canberra industries Inc). Results : The mean activities concentration of 40 K, 226 Ra and 232 Th in soils were 469.72 ± 86.44, 25.17 ± 9.87 and 19.33 ± 6.98 Bq kg - 1 respectively. The mean activities concentration of 40 K, 226 Ra and 232 Th in leaves were 444.76 ± 89.10, 20.43 ± 7.47 and 17.23 ± 7.39 Bq kg - 1 respectively. The mean activities concentration of 40 K, 226 Ra and 232 Th in fruits were 439.54 ± 87.39, 18.96 ± 6.80 and 15.43 ± 5.64 Bq kg - 1 respectively. The mean total absorbed dose rate in air and the mean annual effective dose equivalent for soil sample were estimated at 39.37 ± 11.43 nGy h - 1 and 48.28 ± 14.01 µSv y - 1 . Conclusion : The mean radium equivalent, hazard indices and excess lifetime cancer risks (ELCR) through soil exposures are below the world average, but the mean annual effective dose equivalent and ELCR for different age groups, from radionuclide ingestion through mango consumption in the area are above the world average.