G.D. HOUNDETOUNGAN*,**#, O.H. FACHINAN**,***, S.B.M.G. ADJADOHOUN*, M.B. ZINSOU****, G. ABOGBO*, B. AWEDE*,**, M. ZOUNGRANA *****, K.M. AMOUSSOU-GUENOU*,**
*Faculté des Sciences de la Santé, Université d’Abomey-Calavi, Bénin
**Centre de Recherche en Sciences Morphologiques et Fonctionnelles Humaines, École Doctorale des Sciences de la Santé, Université d’Abomey-Calavi, Bénin
***Institut de Formation en Soins Infirmiers et Obstétricaux, Université de Parakou, Bénin
**** École Polytechnique d’Abomey-Calavi, Université d’Abomey-Calavi, Bénin
*****Université “Joseph Ki-Zerbo”, Burkina Faso
Granite formations are known sources of enhanced natural radioactivity that may contribute to external exposure. In Benin, information on environmental radiation levels remains scarce, particularly in granite quarrying zones. This study evaluated the ambient gamma dose equivalent rate and estimated the annual external effective dose in three granite quarries of the Djidja municipality. A cross-sectional survey was conducted during the fourth quarter of 2023 using a portable AT6101C(E) spectrometer coupled with a GPS for continuous geo-referenced data collection. Measurements were performed on foot within the quarries and by motorcycle in the surrounding residential areas. Data processing was carried out with ATAS Scanner©, RStudio, and Python, and annual effective doses were calculated from average dose rates according to ICRP recommendations. A total of 25,488 measurement points were collected. In the quarries, the ambient gamma dose equivalent rate ranged between 97.02 – 147.83 nSv·h⁻¹, with a mean of 109 ± 10 nSv·h⁻¹, while in residential areas the mean value was 50 ± 18 nSv·h⁻¹. The corresponding annual effective doses were 0.20 ± 0.02 mSv for quarry workers and 0.09 ± 0.03 mSv for the general public. Although these doses are below ICRP limits, the results confirm the contribution of granite formations to ambient radioactivity and underscore the need for regular radiological monitoring in quarry environments. Furthermore, the findings highlight the importance of establishing a national radiological mapping program in Benin to support radiation protection policies.
Key words: Gamma dose rate, natural radiation exposure, radiation protection, granite quarries, Benin
Corresponding author’s e-mail: fofodavid@yahoo.fr