In this work the performance of a screening analytical method for Energy Dispersive X-Ray Fluorescence (EDXRF) analysis in terms of accuracy and precision was evaluated through analysis of rock standard reference mate...In this work the performance of a screening analytical method for Energy Dispersive X-Ray Fluorescence (EDXRF) analysis in terms of accuracy and precision was evaluated through analysis of rock standard reference materials. The method allowed the division of elements into four groups taking into account the excitation energies and measurement conditions of the sample. Two standard reference materials were used and 15 sample replicates were prepared and analyzed, then statistics were applied to assess the precision and accuracy of analytical results. The obtained results show that major compounds or elements (SiO<sub>2</sub>, P<sub>2</sub>O<sub>5</sub>, K<sub>2</sub>O, CaO, Fe<sub>2</sub>O<sub>3</sub>, Ti) can be determined in fine powder sample with a deviation lower than 15%, and a relative standard deviation in the range (1 - 10)%. The deviation was found to be lower than 5% for major compounds such as K<sub>2</sub>O, and CaO, which suggest that the EDXRF is accurate in evaluating major elemental concentrations in rock samples. It was also found that the method seems to be more accurate and precise for major elements than for trace element investigation. This screening analytical method can be used for routine analysis with acceptable results, even though the method should be optimized to increase its precision and accuracy.展开更多
This work draws attention to the effects of the second cause of lung cancer which is also the largest source of exposure to ionizing radiation, radon, during the lockdown recommended by the World Health Organization (...This work draws attention to the effects of the second cause of lung cancer which is also the largest source of exposure to ionizing radiation, radon, during the lockdown recommended by the World Health Organization (WHO) due to the Covid-19 pandemic. The basic assumption is that the exposure times have been assimilated to the 03-month lockdown time and the 02-week maximum incubation period of the disease. Doses during these periods and Relative Risk of Lung Cancer (RRLC), Lung Cancer Cases per year per million people (LCC) and Excess Lifetime Risk of Cancer (ELRC), were evaluated based on the concentrations obtained in high natural background radiation area in Cameroon. The existing exposure situation due to radon is then reevaluated and ranged from 0.76% to 17.55%. These results show that the reconsidered exposure time would be equivalent to the exposure time of a worker over one year, with their respective doses values becoming equivalent. The risks of developing lung cancer were also evaluated and it has been found that due to this pandemic it unfortunately increased.展开更多
This work presents a preliminary study on groundwater samples carried out from selected groundwaters of some localities of Yaounde, Cameroon. Radon concentration was ranged from 0.11 Bq<span style="white-space...This work presents a preliminary study on groundwater samples carried out from selected groundwaters of some localities of Yaounde, Cameroon. Radon concentration was ranged from 0.11 Bq<span style="white-space:nowrap;">∙</span>l<sup>-1</sup> to 1 Bq<span style="white-space:nowrap;">∙</span>l<sup>-1</sup>, with an average of 0.48 Bq<span style="white-space:nowrap;">∙</span>l<sup>-1</sup>. The comparison between the physico-chemical parameters and the radon concentrations in groundwater showed a good correlation between these radon concentrations and the values of Electroconductivity (EC). The annual effective dose due to ingestion of radon in water ranged from 0.30 μSv<span style="white-space:nowrap;">∙</span>y<sup>-1</sup> to 7.90 μSv<span style="white-space:nowrap;">∙</span>y<sup>-1</sup> with an average of 1.93 μSv<span style="white-space:nowrap;">∙</span>y<sup>-1</sup>. The obtained results of this study were shown that the concentrations of radon in groundwaters and annual effective doses due to ingestion of this groundwater were below the references recommended by WHO.展开更多
This study aimed at investigating the content of heavy metals in some marine organisms of the Cameroon Atlantic coast and assessing the health risk due to their consumption by the population. Nine fish and one shrimp ...This study aimed at investigating the content of heavy metals in some marine organisms of the Cameroon Atlantic coast and assessing the health risk due to their consumption by the population. Nine fish and one shrimp species were collected for this study. These fish species were Ethmolosa fimbriata, Drepane africana, Dentex moroccanus, Arius latiscotatus, Scarus hoefleri, Cynoglossus browni, Sardinella madorensis, Pseudotolithus elongatus, Pseudotolithus typus. The shrimp species was Macrobranchium macrobranchium. The elements investigated in this study were: Fe, Co, Cu, Cd and Pb. For seven fish species it was found that the concentration of heavy metals followed the order Fe > Co > Cd > Cu > Pb. For most fish species the Target Hazard Quotient (THQ) value calculated showed the following trend Cd > Co > Pb > Fe ≥ Cu. Cadmium was found to be the main contributor to health risk that may result from the consumption of the fish species under study. The THQ for this element was in the range 0.7 - 1.2 while the Target Cancer Risk (TR) due to ingestion of this metal was in the range (3 × 10<sup>-</sup><sup>4</sup> - 6 × 10<sup>-</sup><sup>4</sup>). These values are slightly above the threshold limits established for both carcinogenic and non carcinogenic risks by the United States, Environmental Protection Agency. The estimated weekly intake of cadmium due to consumption of some fishes under study was greater or equal to the Provisional Tolerable Weekly Intake (PTWI) determined by Food and Agriculture Organization/World Health Organization.展开更多
文摘In this work the performance of a screening analytical method for Energy Dispersive X-Ray Fluorescence (EDXRF) analysis in terms of accuracy and precision was evaluated through analysis of rock standard reference materials. The method allowed the division of elements into four groups taking into account the excitation energies and measurement conditions of the sample. Two standard reference materials were used and 15 sample replicates were prepared and analyzed, then statistics were applied to assess the precision and accuracy of analytical results. The obtained results show that major compounds or elements (SiO<sub>2</sub>, P<sub>2</sub>O<sub>5</sub>, K<sub>2</sub>O, CaO, Fe<sub>2</sub>O<sub>3</sub>, Ti) can be determined in fine powder sample with a deviation lower than 15%, and a relative standard deviation in the range (1 - 10)%. The deviation was found to be lower than 5% for major compounds such as K<sub>2</sub>O, and CaO, which suggest that the EDXRF is accurate in evaluating major elemental concentrations in rock samples. It was also found that the method seems to be more accurate and precise for major elements than for trace element investigation. This screening analytical method can be used for routine analysis with acceptable results, even though the method should be optimized to increase its precision and accuracy.
文摘This work draws attention to the effects of the second cause of lung cancer which is also the largest source of exposure to ionizing radiation, radon, during the lockdown recommended by the World Health Organization (WHO) due to the Covid-19 pandemic. The basic assumption is that the exposure times have been assimilated to the 03-month lockdown time and the 02-week maximum incubation period of the disease. Doses during these periods and Relative Risk of Lung Cancer (RRLC), Lung Cancer Cases per year per million people (LCC) and Excess Lifetime Risk of Cancer (ELRC), were evaluated based on the concentrations obtained in high natural background radiation area in Cameroon. The existing exposure situation due to radon is then reevaluated and ranged from 0.76% to 17.55%. These results show that the reconsidered exposure time would be equivalent to the exposure time of a worker over one year, with their respective doses values becoming equivalent. The risks of developing lung cancer were also evaluated and it has been found that due to this pandemic it unfortunately increased.
文摘This work presents a preliminary study on groundwater samples carried out from selected groundwaters of some localities of Yaounde, Cameroon. Radon concentration was ranged from 0.11 Bq<span style="white-space:nowrap;">∙</span>l<sup>-1</sup> to 1 Bq<span style="white-space:nowrap;">∙</span>l<sup>-1</sup>, with an average of 0.48 Bq<span style="white-space:nowrap;">∙</span>l<sup>-1</sup>. The comparison between the physico-chemical parameters and the radon concentrations in groundwater showed a good correlation between these radon concentrations and the values of Electroconductivity (EC). The annual effective dose due to ingestion of radon in water ranged from 0.30 μSv<span style="white-space:nowrap;">∙</span>y<sup>-1</sup> to 7.90 μSv<span style="white-space:nowrap;">∙</span>y<sup>-1</sup> with an average of 1.93 μSv<span style="white-space:nowrap;">∙</span>y<sup>-1</sup>. The obtained results of this study were shown that the concentrations of radon in groundwaters and annual effective doses due to ingestion of this groundwater were below the references recommended by WHO.
文摘This study aimed at investigating the content of heavy metals in some marine organisms of the Cameroon Atlantic coast and assessing the health risk due to their consumption by the population. Nine fish and one shrimp species were collected for this study. These fish species were Ethmolosa fimbriata, Drepane africana, Dentex moroccanus, Arius latiscotatus, Scarus hoefleri, Cynoglossus browni, Sardinella madorensis, Pseudotolithus elongatus, Pseudotolithus typus. The shrimp species was Macrobranchium macrobranchium. The elements investigated in this study were: Fe, Co, Cu, Cd and Pb. For seven fish species it was found that the concentration of heavy metals followed the order Fe > Co > Cd > Cu > Pb. For most fish species the Target Hazard Quotient (THQ) value calculated showed the following trend Cd > Co > Pb > Fe ≥ Cu. Cadmium was found to be the main contributor to health risk that may result from the consumption of the fish species under study. The THQ for this element was in the range 0.7 - 1.2 while the Target Cancer Risk (TR) due to ingestion of this metal was in the range (3 × 10<sup>-</sup><sup>4</sup> - 6 × 10<sup>-</sup><sup>4</sup>). These values are slightly above the threshold limits established for both carcinogenic and non carcinogenic risks by the United States, Environmental Protection Agency. The estimated weekly intake of cadmium due to consumption of some fishes under study was greater or equal to the Provisional Tolerable Weekly Intake (PTWI) determined by Food and Agriculture Organization/World Health Organization.
