Investigation of Gamma-Emitting Natural Radioactive Contents in Three Types of Vernonia Consumed in Cameroon

Thomas B. Makon, Robert Martin Nemba, Pascal Tchokossa

.
Department of Physics, Obafemi Awolowo University, Ile-Ife, Nigeria.

DOI: 10.4236/wjnst.2011.12007                

Abstract

The specific activity concentration and the derived Annual Effective Dose(AED) in three types of vernonia cultivated and consumed within and outside Cameroon were measured by means of a well-calibrated high-purity germanium detector. Vernonia samples were collected directly from the production farms, oven-dried to a constant mass, crushed, sieved and sealed for at least a month before analysis. The specific activity of ²³⁸U in the three types of vernonia ranged from 20 - 50 Bq kg^-1 with an average of 42 ± 15 Bq kg^-1, ²³²Th from 9 - 22 Bq kg^-1 with an average of 17 ± 7 Bq kg^-1 while ⁴⁰K ranged from 115 - 460 Bq kg^-1 with an average of 302 ± 36 Bq kg^-1. The average AED for ⁴⁰K, ²³⁸U and ²³²Th were 0.15, 0.92 and 0.92μSv y^-1 respectively. ²³⁸U and ²³²Th show the same trends both for the regional distribution of the radioactivity content and the AED. The discrepancies in our data can be attributed to many factors such as geological formation, foliar deposition, type and age of the plant, etc. Although the results obtained represent only some fractions of the standard limit, but they are within some range obtained in other countries.

Keywords

Radionuclides, Specific Activity, Dose, Vernonia, Gamma-Ray, Cameroon

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	B. Marouf, S. A. Mohamad and J. S. Taha, “Assessment of Exposure Rate and Collective Effective Dose Equivalent in the City of Baghdad Due to Natural Gamma Radiation,” The Science of the Total Environment, Vol. 133, 1993, No. 1-2, pp. 133-137
[2]	C. A. Aborisade, J. B. Olomo and P. Tchokossa, “Radioactivity in Palm Oil Produced at Olabisi Ogunbanjo University Oil Mill,” Nigeria Journal of Physics, Vol. 15, No. 1, 2003, pp. 17-19.
[3]	A. Achudume, B. Onibere, F. Aina and P. Tchokossa, “Induction of Oxidative Stress in Male Rats Subchronically Exposed to Electromagnetic Fields at Non-thermal Intensities,” Journal of Electromagnetic Analysis & Application, Vol. 2, 2010, pp. 507-512.
[4]	O. A. Osibote, J. B. Olomo, P. Tchokossa and F. A. Balogun, “Radioactivity in Milk Consumed in Nigeria 10 Years after Chernobyl Reactor Accident,” Nuclear Instruments and Methods in Physics Research A, Vol. 422, 1999, No. 1-3, pp. 778-783.
[5]	P. Tchokossa, J. B. Olomo and O. A. Osibote, “Radioactivity in Community Water Supplies in Ife-Central and Ife-East Local Government Areas of Osun State, Nigeria,” Nuclear Instruments and Methods in Physics Research A, Vol. 422, No. 1-3, 1999, pp. 784-789. doi:10.1016/S0168-9002(98)00997-8
[6]	G. O. Avwiri, P. Tchokossa and C. E. Mokobia, “Natural Radionuclides in Borehole Water in Port Harcourt, Rivers State, Nigeria,” Radiation Protection and Dosimetry, Vol. 123, No. 4, 2007, pp. 509-514.doi:10.1093/rpd/ncl526
[7]	J. B. Olomo, P. Tchokossa and C. A. Aborisade, “Study of Radiation Protection Guidelines in the Use of Building Materials for Urban Dwellings in South-West Nigeria,” Nigeria Journal of Physics, Vol. 15, No. 1, 2003, pp. 7- 13.
[8]	C. R. Cothern, W. I. Lappenbusch and M. Jacqueline, “Drinking Water Contribution to Natural Background Radiation,” Health Physics, Vol. 50, No. 1, 1986, pp. 33- 47. doi:10.1097/00004032-198601000-00002
[9]	M. A. Misdaq and W. Bourzik, “Evaluation of Annual Committed Effective Doses to Members of the Public in Morocco Due to 238U and 232Th in Various Food Materials,” Journal of Radiological Protection, Vol. 24, No. 4, 2004, pp. 391-399. doi:10.1088/0952-4746/24/4/003
[10]	M. K. Fasasi, P. Tchokossa, J. O Ojo and F. A. Balogun, “Occurrence of Natural Radionuclides and Fallout Cesium-137 in Dry-Season Agricultural Land of South Western Nigeria,” Journal of Radioanalytical and Nuclear Chemistry, Vol. 240, No. 3, 1999, pp. 949-952. doi:10.1007/BF02349880
[11]	T. Schlüter and M. H. Trauth, “Geological Atlas of Africa: With Notes on Stratigraphy, Tectonics, Economic Geology, Geohazards, Geosites and Geoscientific Education of Each Country,” 2nd Edition, Springer, Berlin, 2008.
[12]	IAEA International Atomic Energy Agency, “Measurement of Radionuclides in Food and the Environment,” A Guidebook Technical Reports Series No 295, IAEA, Vienna, 1989.
[13]	P. Tchokossa, “Radiological Study of Oil and Gas Producing Areas in Delta State, Nigeria,” Ph.D. Thesis, Department of Physics, Obafemi Awolowo University, Ile-Ife, 2006.
[14]	J. B. Olomo, M. K Akinloye and F. A. Balogun, “Distribution of Gamma Emitting Natural Radionuclides in Soils and Water around Nuclear Research Establishments in Ile-Ife Nigeria,” Nuclear Instruments and Methods in Physics Research A, Vol. 353, No. 1-3, 1994, pp. 553- 557. doi:10.1016/0168-9002(94)91721-3
[15]	Environmental Protection Agency and Food and Drug Administration, “Radionuclides in Institutional Diet Samples,” Radiation Data Report, Vol. 15, 1974, p. 126.
[16]	International Atomic Energy Agency, “Natural and Induced Radioactivity in Food,” IAEA-TECDOC-1287, April 2002.
[17]	United Nations Scientific Committee on the Effects of Atomic Radiations, “Ionizing Radiation: Sources and Biological Effects,” New York, 1982.
[18]	H. Vaelasco, J. Juri, M. A. Beelli and U. Sansone, “Temporal Trends of 137Cs And 40K Activity Flux from Soil to Plant in Grassland Ecosystems,” Journal of Environmental Radioactivity, Vol. 71, No. 3, 2004, pp. 225-241. doi:10.1016/S0265-931X(03)00171-1
[19]	International Atomic Energy Agency, “Summary Report on Post Accident Review Meeting on the Chernobyl Accident Safety Series,” 75-INSAG-1 IAEA, Vienna, 1986.
[20]	N. Karunakara, H. M. Smashekarappa, Y. Narayana, D. N. Avadhani, H. M. Mahesh and K. Siddappa, “226Ra, 40K, 7Be Activity Concentrations in Plants in the Environment of Kaiga, India,” Journal of Environmental Radioactivity, Vol. 65, 2003, pp. 255-266. doi:10.1016/S0265-931X(02)00101-7
[21]	A. I. Shawki and W. Whickers, “Comparative Uptake of U and Th by Native Plants at a U Production Site,” Health Physics, Vol. 54, No. 4, 1988, pp. 413-419. doi:10.1097/00004032-198804000-00004
[22]	P. K. Maniganda, “Activity Concentration of Radionuclides in Plants in the Environment of Western Ghats,” Iran Journal of Radiation Research, Vol. 7, No. 2, 2009, pp. 85-90.
[23]	National Council on Radiation Protection and Measurements, “NCRP Report No. Bethesda MD 20814,” 1994.
[24]	N. N. Jibiri, I. P. Farai and S. K. Alausa, “Estimation of Annual Effective Dose Due to Natural Radioactive Elements in Ingestion of Foodstuffs in Tin Mining Area of Jos-Plateau, Nigeria,” Journal of Environmental Radioactivity, Vol. 94, No. 1, 2007, pp. 31- 40. doi:10.1016/j.jenvrad.2006.12.011
[25]	International Commission on Radiological Protection, “ICRP Publication72: Age Dependent Doses to Members of the Public from Intake of Radionuclides. Ingestion and Inhalation Dose Coefficients,” Annals of the ICRP, Pergamon, Oxford, Vol. 26, No. 1, 1996.
[26]	International Atomic Energy Agency, “International Basic Safety Standards for Protection against Ionising Radiation and for the Safety of Radiation Sources,” Safety Series No. 115, IAEA Vienna, 1996.
[27]	M. A. Misdaq and W. Bourzik, “Determination of Committed Effective Doses from Annual Intakes of 238U and 232Th from the Ingestion of Cereals, Fruits and Vegetables by Using CR-39 and LR—115 II SSNTD,” Journal of Radioanalytical and Nuclear chemistry, Vol. 254, No. 3, 2002, pp. 551-555. doi:10.1023/A:1021650423883
[28]	United Nations Scientific Committee on the Effects of Atomic Radiation, “Annex B: Exposures from Natural Radiation Sources,” UNSCEAR 2000 Report, New York, 2000.
[29]	A. Catal?n, J. C. Fern?ndez-Aldecoa, J. Hern?ndez- Armas, F. Hern?ndez and M. I. Landeras, “Activity Concentrations and Mean Annual Effective Dose of Foodstuffs on the Island of Tenerife, Spain,” Radiation Protection Dosimetry, Vol. 111, No. 2, 2000, pp. 205- 210.
[30]	M. Asefi, A. A. Fathivand and J. Amidi, “Estimation of Annual Effective Dose from 226Ra and 228Ra Due to Consumption of Foodstuffs by Inhabitants of Ramsar City, Iran,” Iran Journal of Radiation Research, Vol. 3, No. 1, 2005, pp. 7-48.
[31]	M. S. Choi, X. J. Lin, S. A. Lee, W. Kim, H. D. Kang, S. H. Doh, D. S. Kim and D. M. Lee, “Daily Intake of Naturally Occurring Radioisotopes in Typical Korean Foods,” Journal of Environmental Radioactivity, Vol. 86, 2008, pp. 1-11.
[32]	V. Changizi, Z. Jafarpoor and M. Naseri, “Measurement of 226Ra, 228Ra, 137Cs and 40K in Edible Parts of Two Types of Leafy Vegetables Cultivatedd in Tehran Provine-Iran and Resultant Annual Ingestion Radiation Dose,” Iran Journal of Radiation Research, Vol. 8, No. 2, 2010, pp. 103-110.