An assessment of health implications of natural radioactivity in the tar sand deposit of Ondo State, southwestern Nigeria.

Abstract

Gamma ray spectrometric and Energy-dispersive X-ray fluorescence analyses were carried out on samples of bituminous sand deposits of Ondo State. The objectives were to determine the presence and level of radioactivity; assess the impact of radioactivity on the environment and provide a geochemical baseline data for its exploitation.

The average specific activity concentrations obtained for Bi-214, T1-208 and Ra-226 in the overburden were 165.64 ± 2.91, 150.25 ± 2.91 and 60.97 ± 2.27 BqKg^-1 respectively. Only Ra-226 with a range of (18.12 ± 3.53 to 36.13 ± 3.15) BqKg^-1 and Pb-214 with a range of (17.17 ± 0.46 to 31.01 ± 0.84) BqKg^-1 were detected in the bituminous sands. The calculated average dose rate in the overburden and the bituminous sands were 68.49nGyhr ^-1 and 8.66nGyhr ^-1 respectively. The mean equivalent doses in the overburden and the bituminous sands were about 0.59mSvyr^-1 and 0.07m

In general, the study confirmed the presence of radionuclides in the overburden and the bituminous sands but their activity levels are within the background values. The calculated radiation values fall below the recommended exposure limit to the populace and thus are not expected to constitute any health hazard.

Key Words: Health implications, radioactivity, tar/bituminous sand, dose-limits.

Ife Journal of Science Vol.6(1) 2004: 57-62