Natural radioactivity contents in commonly consumed leafy vegetables cultivated through surface water irrigation in Lagos state, Nigeria

ABSTRACT In the industrialized area of Lagos, vegetables are mostly cultivated through surface water irrigation. Untreated surface water has the potential of being contaminated with radionuclides from industrial effluents. This study evaluated the concentration of radionuclides in the leafy vegetables cultivated through surface water irrigation in Lagos metropolis and the potential health risks associated with their consumption. The specific activities of 226Ra, 232Th and 40K in some commonly consumed leafy vegetables were determined using High Purity Germanium (HPGe) detector. To assess the radiation hazards associated with the consumption of these vegetables, annual effective dose (AED) and excess lifetime cancer risk (ELCR) were also determined. The specific activities of 226Ra, 232Th and 40K in the investigated samples ranged from 0.49±044 to 6.00±1.19 Bq/kg, with an average value of 2.08±0.59 Bq/ for 226Ra, from 0.10±0.07 to 0.61±0.12 Bq/kg with an average value of 0.85±0.08 Bq/kg for 232Th and from 28.69±3.09 to 126.71±5.86 Bq/kg with an average value of 72.56±5.36 Bq/kg for 40K. The mean activities of 226Ra and 232Th were 40 and 56 times higher than the World Health Organization (WHO) reference values for 226Ra and 232Th in leafy vegetables respectively. The AED estimated from the consumption of vegetables was 0.048 mSv/y, which is about 16 % of the reference AED value for radionuclides of natural origin in the total diet while leafy vegetable represents about 8 % of the total diet of an adult in Lagos. The ELCR obtained from this study was this is lower than the world’s average value. This study has found elevated concentrations of 226Ra and 232Th in leafy vegetables, and noticeable increase in AED associated with 226Ra exposure in the consumption of leafy vegetables cultivated in Lagos. There are therefore potential radiological health risks to the health of the public from long-term consumption of leafy vegetables cultivated through surface water irrigation in Lagos, Nigeria