Radioactivity levels of staple foodstuffs and dose estimates for most of the Tanzanian population

Radioactivity and dose assessment of naturally occurring radionuclides in terrestrial environments and foodstuffs: a review of Bahi district, Tanzania

In this review, the online searchable research articles were scrutinized for the data presented in line with radioactivity and dose estimates from both terrestrial environments and foodstuffs from Bahi district and other parts of Tanzania. The data on natural gamma ray dose rates from Bahi localities were observed with variations among researchers. The observed ranges of radioactivity concentrations (Bq kg-1) in soil were 226Ra (28.5-57.4), 232Th (38.1-521.3), and 40K (562.9-665.0). Deep closed water wells with installed pumps from Ilindi and Bahi Mission reported radioactivity concentration of 238U 3.08 Bq L-1 and Ilindi swamps reported radioactivity concentrations of 226Ra 15.35 Bq L-1, whereas radioactivity concentrations of 238U in cereals were within the annual tolerable limits of 0.001-0.02 Bq kg-1. The quantity and accessibility of published studies, as well as the diversity of the data, point to the necessity for additional studies to be carried out in order to obtain comprehensive baseline data.

Uranium in phosphate rocks and mineral fertilizers applied to agricultural soils in East Africa

Phosphate rock, pre-concentrated phosphate ore, is the primary raw material for the production of mineral phosphate fertilizer. Phosphate rock is among the fifth most mined materials on earth, and it is also mined and processed to fertilizers in East Africa. Phosphate ore can contain relevant heavy metal impurities such as toxic cadmium and radiotoxic uranium. Prolonged use of phosphate rock powder as a fertilizer and application of mineral fertilizers derived from phosphate rock on agricultural soils can lead to an accumulation of heavy metals that can then pose an environmental risk. This work assesses the uranium concentrations in four major phosphate rocks originating from East Africa and four mineral phosphate fertilizers commonly used in the region. The concentration measurements were performed using energy-dispersive X-ray fluorescence spectrometry. The results showed that the uranium concentration in phosphate rock ranged from as low as 10.7 mg kg^-1 (Mrima Hill deposit, Kenya) to as high as 631.6 mg kg^-1 (Matongo deposit, Burundi), while the concentrations in phosphate fertilizers ranged from 107.9 for an imported fertilizer to 281.0 mg kg^-1 for a local fertilizer produced from Minjingu phosphate rock in Tanzania. In this context, it is noteworthy that the naturally occurring concentration of uranium in the earth crust is between 1.4 and 2.7 mg kg^-1 and uranium mines in Namibia commercially process ores with uranium concentrations as low as 100-400 mg kg^-1. This study thus confirms that East African phosphate rock, and as a result the phosphate fertilizer produced from it can contain relatively high uranium concentrations. Options to recover this uranium are discussed, and it is recommended that public-private partnerships are established that could develop economically competitive technologies to recover uranium during phosphate rock processing at the deposits with the highest uranium concentrations.

Radiological Risks Assessment Due to Natural Radioactivity in Mediterranean Sea Fishes

Background and Objectives:

A comprehensive study was carried out for the determination of natural radioactivity in Mediterranean sea fishes and the evaluation of radiological health risks due to their ingestion. All analyzed samples came from the Calabria region, southern Italy, and, in particular, from the district of Reggio Calabria.

Method:

A total of seventy representative samples, five for each investigated species (Sardina Pilchardus, Mugil Cephalus, Scomber Scombrus, Sparus Aurata, Dicentrarchus Labrax, Tonnus Thynnus, Thunnus Alalunga, Xiphaias Gladius, Pagellus Erythrinnus, Engraulis Encrasicholus, Belone Belone, Solea Solea, Merluccius Merluccius, Mullus Surmuletus) were analyzed through HPGe gamma spectrometry. The evaluation of dose levels and lifetime cancer risks for adult members of the population due to the fishes ingestion was also performed.

Results:

The specific activity of 40K was investigated and its mean value was found to be: (157 ± 17) for Sardina Pilchardus, (138 ± 14) for Mugil Cephalus, (118 ± 13) for Scomber Scombrus, (128 ± 14) for Sparus Aurata, (146 ± 17) for Dicentrarchus Labrax, (93 ± 11) for Tonnus Thynnus, (137 ± 15) for Thunnus Alalunga, (98 ± 10) for Xiphaias Gladius, (105 ± 12) for Pagellus Erythrinnus, (132 ± 14) for Engraulis Encrasicholus, (113 ± 12) for Belone Belone, (34 ± 5) for Solea Solea, (76 ± 9) for Merluccius Merluccius and (96 ± 11) for Mullus Surmuletus, respectively.

Conclusions:

The committed effective dose and the lifetime cancer risks for adult members of the population due to the consumption of the investigated samples are lower than the average world value, the maximum acceptable level and the allowed range, respectively. It can then be concluded that the Mediterranean sea fishes consumed in the study area pose no significant health risks to the population from a radiological point of view.

Evaluation of the Radiological and Chemical Risk for Public Health from Flour Sample Investigation

Flour investigation, in terms of physical and chemical pollutants and mineral content, is of great interest, in view of its high consumption for nutritional purposes. In this study, eleven types of flour (five samples for each one), coming from large retailers and employed by people for different cooking food purposes, were investigated through high-purity germanium (HPGe) gamma spectrometry, in order to estimate natural (40K) and anthropogenic (137Cs) radioisotope specific activity and thus, to assess the radiological risk due to the flour ingestion. Inductively-coupled plasma mass spectrometry (ICP-MS) and inductively-coupled plasma emission spectroscopy (ICP-OES) were also employed to evaluate any possible heavy metal contamination and the mineral composition, and to perform multivariate statistical analysis to deduce the flour authenticity. The evaluation of dose levels due to flour ingestion was performed, for the age category higher than 17 years, taking into account the average yearly consumption in Italy and assuming this need to be satisfied from a single type of flour as a precaution. All obtained results are under the allowable level set by Italian legislation (1 mSv y−1), thus excluding the risk of ionizing radiation effects on humans. As far as heavy metal contamination is concerned, Cd and Pb concentrations turned out to be lower than the threshold values, thus excluding their presence as pollutants. Finally, the multivariate statistical analysis allowed to unambiguously correlate flour samples to their botanical origin, according to their elemental concentrations.

Annual committed effective dosage from natural radionuclides by ingestion of local food growing in mineral mining area, Sri Lanka

Sri Lanka's largest mineral sand deposit occurs in Pulmoddai, and the surrounding area of the mineral sand deposit has been identified as a high natural background radiation area. The food crops grown in the area are used for human consumption. However, the long-term consumption of high radioactive foodstuff may cause health defects. The objective of the present study was to assess the radiological impact on individuals due to ingestion of foodstuffs grown in Pulmoddai area. Seasonal food crops growing in the area, including cereals, vegetables, nuts, fruits and yams were collected and used to prepare common meal plans consumed by the residents. Samples were analyzed with high-purity germanium gamma spectrometer for activity concentrations. Activity concentration of ⁴⁰K was observed in higher amounts in every food sample. Trace amounts of ¹³⁷Cs ²³²Th and ⁷Be were also identified. The total committed effective dosage to an adult from gamma-emitting radionuclides from cooked meals was 0.1482 mSv year^-1, and raw foodstuff was 0.0667 mSv year^-1, which are far below than the harmful levels declared by International Atomic Energy Agency. Results concluded that foodstuff and cooked meals consumed by the people who live in Pulmoddai, Sri Lanka, are radiologically safe.

Food Salt Characterization in Terms of Radioactivity and Metals Contamination

The analysis of food salt is very important because of its high consumption by the population, for both medicinal and nutritional use. In this study, nine different samples of food salt (Cyprus black, Himalayan pink, Hawaii red, iodized, hyposodic iodized, Maldon smoked sea, common sea, Breton sea and Persia blue), coming from large Italian retailers and employed by people for different cooking food purposes, were investigated through High Purity Germanium (HPGe) Gamma Spectrometry in order to evaluate the anthropogenic (137Cs) and natural (40K) radioisotopes activity concentration, and used Inductively Coupled Plasma Mass Spectrometry (ICP-MS) in order to assess any possible metals contamination by a comparison between Cu, As, Cd, Hg and Pb concentrations and the limits set by the Italian Legislation. The evaluation of dose levels due to the salt ingestion for the age category higher than 17 years was performed taking into account the human body daily need of about 10 g of salt, and in the precautionary hypothesis, this need was satisfied from a single type of salt. All obtained results are under allowable levels (1 mSv/year), thus excluding the risk of ionizing radiation effects on humans. Regarding to the metals concentration, experimental results show that it is lower than the contamination threshold values, thus excluding their presence as pollutants.

The Natural Radioactivity in Food: A Comparison Between Different Feeding Regimes

Background:

In this article a comprehensive study was carried out for the determination of natural radioactivity in animal and vegetable food (meat, fish, milk and derivates, legumes, cereals and derivates, fruit, hortalizas, vegetables, vegetable oils) typical of different feeding regimes, for the age category higher than 17 years.

Methods:

A total of eighty-five samples of Italian origin, coming from large retailers during the years 2014, 2015 and 2016, were analyzed through HPGe gamma spectrometry.

Results:

The specific activity of 40K was investigated and its mean value was found to be: (106.3 ± 6.9) Bq/kg for bovine, swine and sheep meat; (116.5 ± 9.7) Bq/kg for fish; (52.9 ± 3.1) Bq/kg for milk and derivates; (271.9 ± 16.7) Bq/kg for legumes; (67.2 ± 4.7) Bq/kg for cereals and derivates; (52.7 ± 4.4) Bq/kg for fruit; (72.9 ± 5.6) Bq/kg for hortalizas; (83.9 ± 6.5) Bq/kg for vegetables; lower than the minimum detectable activity for vegetable oils. For animal food the highest mean 40K activity concentration was found in fish samples; for vegetable food the highest one was detected in legumes.

Conclusion:

The evaluation of dose levels due to the food ingestion typical of Mediterranean, Vegetarian and Vegan diets was performed. The annual effective dose was found to be 0.16 mSv/y, 0.41 mSv/y and 0.54 mSv/y, respectively.