Assessment of natural radioactivity and associated radiation hazards in sand building material used in Douala Littoral Region of Cameroon, using gamma spectrometry

Twenty-four sand samples were collected from different sand quarries from Douala Littoral Region (Wouri, Dibamba, Mungo and Docteur Anse rivers and Atlantic Sea) along the Guinea Golf. These samples were investigated using gamma-ray spectrometry system. Highest values of ²²⁶Ra, ²³²Th and ⁴⁰K measured specific activities expressed in Bq Kg⁻¹ units were, respectively, 146.7 (in Youpoue–Bamenda 2) 102.9 (in Village 1) and 928 (in Northern Akwa 6) while the lowest values were found to be, respectively, 11.8 (in Northern Akwa 6), 8.0 (in Bonaberi–Bonamikano 4) and 54.0 (Youpoue 3). The potential radiological hazards parameters were assessed by calculating successively radium equivalent activity (Ra_eq), outdoor absorbed gamma dose rate (D_out), annual effective dose rate, internal hazard (H_in) and external hazard (H_ex) indices and alpha and gamma index from using those sand in the construction of dwellings and large buildings. Results obtained show that annual dose absorbed by inhabitants due to sand construction use in Douala is below 1.0 mSv year⁻¹. Therefore, most of the types of sands studied and incorporated in constructions appear to be safe as building material. The outputs from this research will be useful to assess the radiation hazards of sand building material in humans and to initiate a sand database together with a radiological map of the area at stake.