Correlation between Ground 222Rn and 226Ra and Long-Term Risk Assessment at the at the Bauxite Bearing Area of Fongo-Tongo, Western Cameroon
by
,
Léonard Boris Djeufack
1,2, 
Guillaume Samuel Bineng
1,
Oumar Bobbo Modibo
2,
Joseph Emmanuel Ndjana Nkoulou II
2 and
Saïdou
1,2,* 1
Nuclear Physics Laboratory, Faculty of Science, University of Yaoundé I, Yaoundé P.O. Box 812, Cameroon
2
Research Centre for Nuclear Science and Technology, Institute of Geological and Mining Research (IRGM), Yaoundé P.O. Box 4110, Cameroon
*
Author to whom correspondence should be addressed.
Radiation 2022, 2(4), 387-404; https://doi.org/10.3390/radiation2040029
Submission received: 9 October 2022
/
Revised: 5 November 2022
/
Accepted: 9 November 2022
/
Published: 14 November 2022
(This article belongs to the Special Issue Radiation in the Human Life—Environment and Medical Use)
Simple Summary
This paper presents a study of radioactivity in soil that included an assessment of radiological risk parameters and long-term health risks from exposure to naturally occurring radionuclides in soil at the bauxite-bearing area of Fongo-Tongo in Western Cameroon. The radionuclides measured in the soil had concentration values above the recommended limits. However, the total long-term excess risk at the site decreased progressively over the years, and the maximum value of 8.58 × 10−3 was obtained at T = 0 years. In addition, the external pathway is the largest contributor to the total excess risk assessed inside the building. The maximum risk value for this pathway, which is 2.33 × 10−2, was obtained at T = 30 years before decreasing sharply thereafter.
Abstract
The aim of the current work was to study natural radioactivity in soil and the correlation between 222Rn and 226Ra in the ground and to assess the onsite and indoor long-term excess cancer risk at the bauxite bearing area of Fongo-Tongo in Western Cameroon. 222Rn was measured in the ground at a depth of one meter, using Markus 10 detector. 226Ra, 232Th, and 40K activity concentrations were measured in soil by two techniques, in situ and laboratory gamma spectrometry. The mean values of 222Rn concentrations in the ground were 69 ± 18 kBqm−3 for Fongo-Tongo and 82 ± 34 kBq m−3 for the locality of Dschang, respectively. The mean values of 226Ra, 232Th, and 40K activity concentrations obtained with in situ gamma spectrometry were 129 ± 22, 205 ± 61, and 224 ± 39 Bq kg−1 for 226Ra, 232Th, and 40K, respectively, and those obtained by laboratory gamma spectrometry were 129 ± 23, 184 ± 54, and 237 ± 44 Bq kg−1, respectively. A strong correlation between 222Rn and 226Ra activity concentrations determined by in situ and laboratory measurements (R2 = 0.86 and 0.88, respectively) was found. In addition, it is shown that the total excess cancer risk has a maximum value of 8.6 × 10−3 at T = 0 year and decreases progressively in the long term. It is also shown that 226Ra makes a major contribution, i.e., above 70%, to the total excess cancer risk.
Keywords:
radium-226; radon-222; life excess cancer risk
