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The present work reports indoor Radon-222 activity concentration measurements, external gamma dose rate measurements, and assessment of cancer risk in the different dwellings in Ebolowa town, southern Cameroon. The geological formations of this studied area are mainly granites. This studied area extends over the equatorial climatic zone. The mean temperature of the zone varies from 25°C to 26°C with two rainy and two dry seasons with a relative humidity of (70–80) % recorded throughout the year. The indoor radon activity concentrations were carried out using RADTRACK2 devices, which are the alpha track detectors made of CR-39 plastic films contained in an antistatic black holder. Each device was hung in an inhabited room of each selected dwelling for an average period of three months. Radon concentrations in dwellings ranged between (23 ± 10) Bq m–3 and (2620 ± 480) Bq m–3 with an arithmetic mean of 135.6 Bq m–3 and a geometric mean of 63 Bq m–3. The estimated annual effective doses due to external gamma exposure ranged from (0.15 ± 0.01) mSv y−1 to (0.38 ± 0.06) mSv y−1 with an average value of 0.26 mSv y−1. The estimated annual effective dose due to indoor radon ranged between 0.43 mSv y−1 and 49.6 mSv y−1 with an arithmetic mean of 2.6 mSv y−1. This value was below the International Commission on Radiological Protection (ICRP) recommended action level. The Excess Lifetime Cancer Risk (ELCR) ranged from 1.39% to 158% with a mean value of 8.2%. According to these results, cancer risk due to inhalation of radon-222 must be further investigated in the population living in Ebolowa town. [ABSTRACT FROM AUTHOR]

The present work was aimed at measuring indoor radon activity concentrations in dwellings in Mvangan locality, South Cameroon, in order to assess the extent of measures that may be necessary for controlling public indoor radon exposure in this area. Measurements were carried out using passive solid-state nuclear track detectors (RADONAVA Inc. RadTrak2, Sweden) following ISO 11665-4 standard. Radon concentration ranged between 36 ± 20 and 150 ± 30 Bq m−3 with arithmetic and geometric means values of 64 ± 25 and 60 ± 1 Bq m−3, respectively. These mean values were greater than worldwide values presented by United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), which are, respectively, 40 and 30 Bq m−3. 96% of dwellings that have radon concentrations below the World Health Organization (WHO) reference level of 100 Bq m−3, whereas 4% of dwellings have radon concentrations higher than this level but lower than 300 Bq m−3, the International Commission on Radiological Protection (ICRP) reference level. Annual effective doses due to indoor radon ranged between 0.7 and 2.8 mSv y−1 with an arithmetic mean value of 1.2 ± 0.5 mSv y−1. These values were below the lower limit of the ICRP-recommended action level interval 3–10 mSv y−1. It has been observed that annual effective dose received by residents in cement bricks dwellings were not significantly different (P -value = 0.565) than those received by residents in mud dwellings in Mvangan locality. The mean number of persons expected to be diagnosed with or die from cancer (solid cancers and leukemia) were 162 ± 48 (61 ± 25 for males and 101 ± 41 for females) and 82 ± 24 (33 ± 13 for males and 49 ± 20 for females), respectively. The results obtained in this study prove that the populations of Mvangan locality are exposed to a relatively low potential risk of cancer incidence and mortality. [ABSTRACT FROM AUTHOR]

We report on the investigation of lead sorbed onto volcanic ashes using x-ray absorption spectroscopy (XAS) and complementary techniques such as x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive x-ray spectroscopy (EDS). The ashes from Cameroon volcanic line are used for adsorption applications to remove lead in aqueous solutions. SEM and EDS revealed a heterogeneous structure with particles of different sizes, distributions and the presence of lead on the samples sorbed onto volcanic ashes. The obtained maximum adsorption capacity of the volcanic ashes was 7.60 mg·g−1 at pH 5. According to our results, a mixture of Pb chemical species and a strong interaction with the volcanic ashes surface was found. The XAS results showed that the lead removal occurred mainly by microprecipitation of lead acetate and carbonate (cerussite) and ion exchange. Additionally, it is shown that XAS can be applied to solve adsorption mechanisms. • The Cameroon volcanic ash can be used as a potential economically sustainable adsorbent for removing lead from wastewater. • The oxidation state of Pb(II) does not change suggesting that most components in the VA material are lead compounds. • Lead sorbed by volcanic ash sample is mainly composed of lead associated with carbonate, acetate, monoxide, and goethite. • The lead sorption occurred mainly by microprecipitation of lead acetate, carbonate, and ion-exchange forming lead monoxide. • In the lead sorbed by volcanic ash sample, the first and second shells are coordinated to oxygen and lead atoms respectively. [ABSTRACT FROM AUTHOR]

The present work was aimed at measuring indoor radon activity concentrations in dwellings in Mvangan locality, South Cameroon, in order to assess the extent of measures that may be necessary for controlling public indoor radon exposure in this area. Measurements were carried out using passive solid-state nuclear track detectors (RADONAVA Inc., RadTrak2, Sweden) following ISO 11665-4 standard. Radon concentration ranged between 36 ± 20 and 150 ± 30 Bq m-3 with arithmetic and geometric means values of 64 ± 25 and 60 ± 1 Bq m-3, respectively. These mean values were greater than worldwide values presented by United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), which are, respectively, 40 and 30 Bq m-3. 96% of dwellings that have radon concentrations below the World Health Organization (WHO) reference level of 100 Bq m-3, whereas 4% of dwellings have radon concentrations higher than this level but lower than 300 Bq m-3, the International Commission on Radiological Protection (ICRP) reference level. Annual effective doses due to indoor radon ranged between 0.7 and 2.8 mSv y-1 with an arithmetic mean value of 1.2 ± 0.5 mSv y-1. These values were below the lower limit of the ICRP-recommended action level interval 3-10 mSv y-1. It has been observed that annual effective dose received by residents in cement bricks dwellings were not significantly different (P-value = 0.565) than those received by residents in mud dwellings in Mvangan locality. The mean number of persons expected to be diagnosed with or die from cancer (solid cancers and leukemia) were 162 ± 48 (61 ± 25 for males and 101 ± 41 for females) and 82 ± 24 (33 ± 13 for males and 49 ± 20 for females), respectively. The results obtained in this study prove that the populations of Mvangan locality are exposed to a relatively low potential risk of cancer incidence and mortality., (© The Author(s) 2022. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)