Natural radioactivity in soils around mega coal-fired cement factory in Nigeria and its implications on human health and environment

Abstract

Cement industry is one of the anthropogenic activities capable of mobilizing and propagating naturally occurring radioactive materials (NORM) in human environment to levels that may become detrimental to human health. A pilot survey of radiological implications of a mega cement factory (AshakaCem), north-eastern Nigeria, on human health and the environment was conducted using high-purity germanium (HPGe) gamma-ray spectrometric technique. Average activity concentrations for 226Ra, 232Th and 40K in the soil samples were found to be 7.41 ± 0.44, 16.27 ± 0.84 and 196.11 ± 9.08 Bq kg−1, respectively. These values were lower than the world mean values documented by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). Calculated radiation hazard parameters associated with the studied soil samples showed mean air absorbed dose rate of 21.43 nGy h−1, with attendant annual effective dose of 0.03 mSv y−1 and average excess lifetime cancer risk of 0.9 × 10−4. Statistical analysis revealed strong relationship between calculated hazard parameters and the investigated natural radionuclides in the studied soil samples and confirmed that 226Ra, 232Th and 40K were major contributors to radiation dose. Results obtained from this study fall within acceptable limits provided for human safety and environmental protection. Thus, the operations of AshakaCem did not provide any significant radiological risk to workers nor pose any immediate radiological threat to the environment.