Activity concentrations and population dose from radium-226 in food and drinking water in Taiwan

The radionuclides contamination in eggs as an environmental marker: a systematic review

Foods are contaminated with natural and man-made radionuclides. The aim of this systematic review was to determine the amount and type of radionuclides in eggs, as well as the biomarker capability of eggs. The research studies with keywords radionuclide, radioisotopes, contamination and egg were searched in PubMed, Scopus, and Science Direct databases, regardless of publication time. A number of 70 studies were obtained and only 13 articles were finally selected according to exclusion, inclusion criteria and quality assessment results. Studies which detected radionuclide in the hen eggs were selected. The highest frequency of radionuclides belonged to Ra-226 and Cs-137. The index of natural radionuclides is Ra-226 and the index of synthetic radionuclides is Cs-137. The local eggs, in addition to determining food contamination, can also be a good biomarker for identifying environmental contamination.

The dynamics of the detection of 226Ra in water by scintillation counting in nonequilibrium conditions

The conventional methods for the ²²⁶Ra determination by liquid scintillation counting require to attain secular equilibrium between ²²⁶Ra and ²²²Rn prior to the counting. This study describes a method that allows the immediate counting of a sample after the dissolution of Ba(Ra)SO₄ in EDTA. This results from a detailed modelling of the activity of the parent ²²⁶Ra and its daughters in both the aqueous and organic scintillator phases. This methodology was tested on standard solutions of ²²⁶Ra showing promising results.

Determination of natural radioactivity in products of animals fed with grass: A case study for Kars Region, Turkey

In this research, the activity concentrations of ⁴⁰ K, ²³²Th and ²²⁶Ra in 41 grass samples collected from Kars region, Turkey, were determined using gamma ray spectrometry. Natural radioactivity concentrations in animal food products were calculated based on activity concentrations of these radionuclides in pasture-grass samples and dry-grass consumption of animals. The average annual effective dose from these radionuclides for local consumers due to indirect ingestion of cow milk, sheep milk, poultry, mutton and beef consumption have been calculated as 9.01, 0.24, 1.76, 0.38 and 5.25 µSv y^-1, respectively. Furthermore, the calculated average annual effective dose values for adults are within the values found in other countries worldwide. These results show that animal products can be safe for human consumption in terms of radiation exposure due to the natural radionuclides studied.

Deconvolution of liquid scintillation alpha spectra of mixtures of uranium and radium isotopes

A method for the determination of uranium and radium isotopes in water samples is proposed. Liquid scintillation techniques were used for collecting alpha spectra, which were then analyzed by fitting the alpha peaks with overlapping Gaussians. The analysis can quantify the observed isotopes with accuracy depending on the activity of each isotope. In order to simulate the peaks with Gaussian normal distribution functions, the centroid of each peak as well as the full width at half maximum (FWHM) are required, as they depend on the quenching of the sample. For this purpose, samples with known activities of 226Ra and its decay products and also of the uranium isotopes 238U and 234U, at various quenching levels, were used to establish the correlation of the peaks' shift with the quench effect. In addition, the correlation of the FWHM with the centroid of a peak was determined, using the same procedure. Following the above analysis technique, an average of 97+/-2% of detection efficiency and a lower limit of detection of 8.2 mBq kg(-1) for alpha isotopes were achieved.

Life exposure to 226Ra and possible consequences

This paper presents a model of continuous exposure to 226Ra by water consumption over a 55-year period. The effects of 226Ra concentration in drinking water were investigated. Reaching the peak at the age of 16, the assessed effective dose has shown that children are more sensitive to radiation than adults. It has been found that consumption of 226Ra-rich water during certain period of life increases consequent effective doses. The earlier the exposure, the higher amount of 226Ra could be retained causing the higher values of effective dose later in life. However, long-term exposure to 226Ra in drinking water as well as consumption of 226Ra-rich water during a certain period of life does not indicate the appearance of malignant diseases in the year of exposure and later in adults.

Simultaneous determination of 226Ra and 210Pb in groundwater and soil samples by using the liquid scintillation counter-suspension gel method

A method for the simultaneous determination of 226Ra and 210Pb in groundwater and soil samples by liquid scintillation counting was developed. Radium and lead were separated together from the samples as Ba(Ra) x PbSO4 co-precipitate, which was centrifuged and dissolved with 0.1 M EDTA solution (pH 9.0). Radium was separated as Ba(Ra)SO4 co-precipitate by adding ammonium sulfate and adjusting the pH of the solution to 4.2. Lead remaining in the solution was separated as PbSO4 precipitate by adding 9 M sulfuric acid. These Ba(Ra)SO4 and PbSO4 precipitates were purified with EDTA solution and used for measurement. To save time and to make counting samples simpler, direct counting of Ba(Ra)SO4 and PbSO4 precipitates instead of the phosphoric acid fusion method was attempted. Ba(Ra)SO4 and PbSO4 precipitates were suspended in the scintillation gel, and measured. Two liquid scintillation cocktails, Instagel XF and UltimaGold AB were used to prepare the counting samples. A mixture of water (40%), Instagel XF (40%) and UltimaGold AB (20%) formed a stable gel. Activities of 226Ra and 210Pb were calculated from the alpha spectrum of Ba(Ra)SO4 and beta spectrum of PbSO4, respectively. The long-term stability of the suspension gel was good. The analytical results of 226Ra and 210Pb in spiked groundwater samples were in good agreement with the known concentrations of 226Ra and 210Pb. The analytical values of 226Ra and 210Pb in the soil reference samples were within 11.5 and 1.6% of the relative error from the reference values, respectively.