The annual effective dose due to natural radionuclides in the reservoir and tap water in Yaoundé area, Cameroon

Abstract

The average concentrations of radionuclides of reservoir and tap water in the Yaoundé area, with a population of 1.5 million inhabitants were estimated from measurements of mean specific activity using a well calibrated Canberra NaI(Tl) detector system. Water samples were collected from reservoirs and taps during the dry and the rainy seasons respectively in December 2002 and July 2003. The radionuclides observed with regularity belonged to the decay series naturally occurring radionuclides headed by ²³⁸U and ²³²Th as well as the non-series nuclide ⁴⁰K. The average specific activity values obtained for ⁴⁰K, ²²⁶Ra and ²²⁸Ra, respectively were for reservoir water 70 ± 11 BqL^–1; 8.7 ± 3.5 BqL^–1; 0.6 ± 0.2 BqL^–1 during the dry season, and 50 ± 9 BqL^–1; 8.5 ± 3.7 BqL^–1; 0.6 ± 0.2 BqL^–1 during the rainy season and for tap water, we have respectively 111 ± 17 BqL^–1; 11.4 ± 3.7 BqL^–1; 1 ± 0.3 BqL^–1 during the dry season, and 51 ± 10 BqL^–1; 9 ± 3.5 BqL^–1; 0.7 ± 0.2 BqL^–1 during the rainy season. The annual effective dose received by Yaoundé adult population as a result of ingestion of this drinking water is respectively 0.925 mSv for the reservoir water and 1.052 mSv for the tap water.