ACTIVITY CONCENTRATIONS OF NATURALLY OCCURRING RADIONUCLIDES IN SOME COMMERCIAL BOTTLED WATERS FROM PARTS OF SOUTHWESTERN NIGERIA

Abstract

In this work, the presence of natural radioactivity in bottled waters from parts of south-west Nigeria was investigated. The activity concentrations of 226Ra, 232Th and 40K in the water samples were ob-tained using a high-purity germanium detector. The ranges of activity concentrations obtained for 232Th, 226Ra and 40K were 0.15 to 1.25Bq l-1, 0.02 to 2.94Bq l-1 and 6.96 to 46.47 Bq l-1, respectively. 40K has the highest activity concentration in the bottled water samples while 232Th has the least value. The activity concentrations obtained together with ingested dose conversion factors, were used to calculate the annual effective doses for six age groups ranging from < 1 to >17 years. The calculated total annual effective doses (mSvy-1) ranged from 0.01 to 4.16 and the values are age dependent (highest for < 1year and lowest for 7-12years age groups). The results showed that the average annu-al effective dose for 35% of the bottled water brands were below the World Health Organization (WHO) recommended level of 0.1 mSvy-1 for drinking water. Furthermore, out of the remaining 65% that were higher than the WHO recommended level, 9% were higher than 1 mSvy-1, which is the radia-tion exposure limit for the general public according to the recommendation of the International Com-mission on Radiological Protection. Consequently, consumption of some of the bottled water brands investigated in this study could constitute radiological hazard especially for the < 1 and 12-17years age groups.