Browsing by Author "Msaki, P."

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    Radioactivity in Products Derived from Gypsum in Tanzania
    (Nuclear Technology Publishing, 2000) Msaki, P.; Banzi, Firmi B.
    Scientific investigations have long concluded that prolonged exposure to low dose radiation can induce deleterious effects in humans. The aim of this paper is to investigate the radioactivity of gypsum and gypsum derived products as part of a bigger project aimed at establishing radiation levels in materials or/and products suspected to have natural radioactivity radiation risk in Tanzania. In response to the concern expressed by the users of chalk sticks in some schools in Arusha municipality, it was found necessary to establish levels of radioactivity in this product and associated radiation risk. Natural radioactivity content was determined in chalk dust, natural gypsum and normal background soil using a hyper pure germanium spectrometer (HPGe). The soil measurements were used as control. Results have shown that the concentration of 226Ra and 228Ra nuclides found in chalk dust were 24.25 Bq.kg21 and 22.86 Bq.kg21 , respectively. These levels were lower or comparable to the corresponding 34.2 Bq.kg21 and 21.5 Bq.kg21 , respectively, found in soil. However, the radioactivity levels found in the chalk dust were five times higher than that found in the gypsum 5 Bq.kg21 for 226Ra and 4 Bq.kg21 for 228Ra. These values compare well with the value recorded for natural gypsum in Denmark of 7 Bq.kg21 for 226Ra and 4 Bq.kg21 for 228Ra by UNSCEAR. The calculated external (0.21) and internal (0.31) hazard indices due to radioactivity in chalk dust were respectively, lower than (0.26 and 0.35) hazard indices calculated for normal background soil. In both cases, the hazard indices were lower than the acceptable limits (<1) recommended for building materials. This study has shown that natural gypsum and gypsum derived products have traces of radioactivity. However, the associated levels are not detrimental to health.
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    A survey of background radiation dose rates and radioactivity in Tanzania
    (2002-02) Banzi, Firmi B.; Msaki, P.; Makundi, Ismael
    Potential terrestrial sources of naturally occurring elevated radiation levels have been identified in Tanzania. Thus, efforts are currently being undertaken to create a natural radiation database, in the form of a radiation level map of natural radioactivity, to be used to assess the associated radiation risk to public and workers. Background radiation dose rate was determined with thermoluminescent dosimeters for 7 y (1993-1999) in five stations. The average background radiation dose rates for these stations were as follows: Tropical Pesticides Research Institute (TPRI) (102 +/- 7 nGy h(-1)), Same (98 +/- 2 nGy h(-1)), Namanga (98 +/- 5 nGy h(-1)), University of Dar Es Salaam (99 +/- 2 nGy h(-1)), and Kilimanjaro Christian Medical Center (121 +/- 3 nGy h(-1)). These stations were found convenient from an economic point of view since the project has no funds to cover wider and/or more remote areas in Tanzania. For the sake of comparison, similar measurements were made for the same period at Minjingu phosphate mine. The mine was one of the suspected areas with elevated levels of natural radioactivity. The radiation dose rate measured in this mine was about fourteen times higher (1,415 +/- 28 nGy h(-1)) than the average value obtained in northern Tanzania (98 nGy h(-1)). The high average activity levels of phosphate (5760 +/- 107 Bq kg(-1) for 261Ra, 497 +/- 5 Bq kg(-1) for 228Ra, 350 +/- 6 Bq kg(-1) for 228Th, and 280 +/- 5 Bq kg(-1) for 40K) and radiation dose rate recorded show that Minjingu phosphate mine has higher values than the highest radioactivity in phosphate compiled by the United Nations Scientific Committee on the Effect of Atomic Radiation. In view of these findings, a comprehensive risk-management strategy for reduction of radiation risk to the public and mine workers should be put in place. Efforts are currently being made to seek support to improve the background radiation database for subsequent assessment of radiation risk to miners and the societies in the