Determination of Activity Concentrations and Soil to Cassava Transfer Factors of Natural Radionuclides in Ikot Ekpene Local Government Area, Akwa Ibom State, Nigeria

Natural radioactivity exists in primordial formations such as rocks, soils, water and air where long lived radionuclides such as , , and their affiliates are found. This work was done to determine the specific activity of radionuclides, soil to cassava transfer factor and the effective dose due to consumption of radionuclide in cassava products in Ikot Ekpene Local Government Area, Akwa Ibom State. The specific activity of 40K, 238U and 232Th in soils and cassava in the study area was measured using gamma spectrometry. Mean specific activity in soils ranged from BDL to 153.46 ± 10. 99 Bq/Kg for 40K; BDL to 31. 22 ± 7.49 Bq/Kg for 238U and 1.03 ± 0.10 to 12.71 ± 1.24 Bq/Kg for 232Th. Mean specific activity of the radionuclides in cassava in all locations ranged from 119.86 ± 8.61 to 601.28 ± 43.23 Bq//Kg for 40K; below detectable limit (BDL) to 15. 89 ± 1.55 Bg/Kg for 238U and BDL to 15. 89 ± 1.55 Bq/kg for 232Th. Transfer factors ranged between 3.64 to 4.18 for 40K; 1.30 to 1.82 for 238U and 0.51 to 0.72 for 232Th. Effective ingestion dose due to the consumption of cassava from the area ranged between 0.99 mSv/yr to 1.08 mSv/yr and 2.68 mSv/yr to 29.16 mSv/yr for children and adult respectively. Most of the TF and effective ingestion dose results for this study were above the recommended value of unity which suggests that consumption of cassava from the studied area may pose radiological health.

Assimilation of natural Radionuclides in the wheat plant from cultivated soil

The intake of naturally nuclides 238U, 232Th, and 40K by wheat crop from two different fertilization soils of Iraq was studied under natural farm conditions. The overall mean of soil to wheat cereal transfer factors (TF) was studied and observed to be in the range of 0.6 × 10-3 to 0.70 × 10-3 for 238U, 0.11 × 10-3 to 0.13 × 10-3 for 232Th and 0.054 to 0.055 for 40K. The calculated values of TF for wheat grain denote that 40K are the significant radionuclides that are transferred in grain. This evaluation is most important for the production of foodstuffs with low contents of radionuclides. The assimilation of radionuclides by consuming wheat cereals from the farms studied gives a small fraction to the total annual ingestion dose received by a person due to naturally existent radioactivity material in the environment. This study proves that the natural radioactivity and Ingestion effective dose was lower than the safe, which the total of the dose received from 238U and 232Th due to consumption of wheat grains alone from fertilized field 0.056 and 0.045 mSv y-1 from the unfertilized field total ingestion dose, the dose received from 40K due to the consumption from the unfertilized and fertilized field was 0.0102 and 0.0137 respectively. The dose values were less than the limit value of 0.30 mSv y-1. Therefore, the consumption of these foods has no health risks. This process may help to obtain basics on radiological health regulations The activity concentration of natural radionuclides 238U, 232Th, and 40K in fertilized and unfertilized soil and wheat plants growing into is statistically significant at 1% level of significance using an independent t-test.

Assessment of 232Th, 226Ra, 137Cs, and 40 K concentrations and annual effective dose due to the consumption of Vietnamese fresh milk

Vietnam has little data on radionuclide concentrations in milk, despite steadily increasing domestic consumption. Eight milk brands were investigated by gamma-spectrometry, and the resulting ingestion dose was calculated. The 232Th, 226Ra, 137Cs, and 40K concentrations varied from 0.60 ± 0.19 to 1.21 ± 0.24, 1.45 ± 0.18 to 2.45 ± 0.24, below detection limit to 0.13 ± 0.06, and 341 ± 6 to 387 ± 7 Bq/kg (dry w.t). The total average Annual Effective Dose for all age groups were similar for all brands, and concentrations are far less than the WHO guidance level. All brands are safe for consumption.

Radiological Impact Assessment of Farm Soils and Ofada rice (Oryza sativa japonica) from Three Areas in Nigeria

Oryza sativa japonica (ofada rice) is largely grown in Aramoko, Abakaliki and Ofada are communities and consumed by both the poor and rich in Nigeria. A total of twenty ofada rice farmlands were identified in each study area and rice samples were randomly collected, thoroughly mixed to make a representative sample from each farmland. Soil samples were collected in each farm to a depth of 5-15cm from at least eight different points and thoroughly mixed together to form a representative sample. The samples were thereafter taken to the laboratory for preparation and spectroscopic analysis. A well-calibrated NaI(Tl) gamma-ray detector was used in spectrometric analysis of the samples and descriptive statistics was used to analyze the results. The respective mean 40K, 238U and 232Th activity concentrations in the rice were 261.8±52.5Bq/kg, 9.6±1.2Bq/kg and 8.7±1.0Bq/kg (Ofada); 257.3±39.0Bq/kg, 9.3±1.1Bq/kg and 7.8±1.8Bq/kg (Abakaliki); and 248.2±54.8Bq/kg, 9.3±0.9Bq/kg and 7.6±1.5Bq/kg (Aramoko). The respective mean 40K, 238U and 232Th activity concentrations in the soils were 333.9±62.8Bq/kg, 11.1±1.1Bq/kg and 11.0±1.4Bq/kg (Ofada); 306.8±36.0Bq/kg, 10.7±0.8Bq/kg and 9.4±1.8 Bq/kg (Abakaliki) and 321.8±42.4Bq/kg, 10.9±0.5Bq/kg and 9.5±0.6Bq/kg (Aramoko). The highest mean ingestion dose of 106.0±8.0µSv/y and outdoor effective dose of 32.4±3.40µSv/y were recorded in Ofada community. The highest mean ingestion cancer risk of (0.33±0.004) x10-3was recorded in Aramoko. The results indicated significantly lower radionuclide ingestion dose than the world limit value of 290µSv/y and lower cancer risks than the UNSCEAR recommended limit of 0.29x10-3, therefore consumption of ofada rice from the areas may not pose any serious health impact.

COEFFICIENTS FOR ESTIMATING PRENATAL DOSE IN PREGNANT WORKERS FROM ACUTE INTAKES

Inhalation and ingestion dose coefficients for the embryo and fetus from intakes of radionuclides by the mother are provided in the International Commission on Radiological Protection (ICRP) Publication 88 for intake of each of 74 radionuclides. To address the many other possible radionuclides to which workers may be exposed, effective dose coefficients were developed for the embryo/fetus for all additional radionuclides addressed in ICRP Publication 107 with half-life of 10 min or more. The general approach was to use the estimated dose to the mother’s uterus during pregnancy as a scalable proxy for the dose to the embryo/fetus. The set of scaling factors used in the study was derived from analyses of the relationships of the dose to the mother’s uterus and the effective dose to the embryo/fetus for the ~400 cases (considering two intake modes and multiple forms of many of the radionuclides) addressed in Publication 88.