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This study aimed to measure tritium (3H) concentrations in Thailand. Nationwide tap water samples were collected in July 2021. Rainwater samples were collected monthly during May–October 2020, April–October 2021, and February–March 2022 in Chonburi province and in Chiang Mai province during July–November 2021, January 2022, and March–June 2022. The measurements of 3H activity concentrations were conducted by Osaka Sangyo University (OSU) and were compared with measurements by the Thailand Institute of Nuclear Technology (TINT). The results from OSU and TINT showed that 3H concentrations in tap water were matched in the ranged from 0.08 ± 0.03 to 0.28 ± 0.04 Bq L−1, while those in rainwater samples collected from Chonburi province and Chiang Mai province are also matched in the ranged from 0.11 ± 0.02 to 0.21 ± 0.03 Bq L−1 and 0.19 ± 0.02 to 0.57 ± 0.04 Bq L−1, respectively. Our measured result suggests that 3H concentration in tap water and rainwater shows a similar relation depending on latitude. [ABSTRACT FROM AUTHOR]

Monitoring of tritium concentration in tap water is an essential tool to determine the effective dose received from tap water. Liquid scintillation counting (LSC) is a widely used technique for determining tritium in water. Due to the very low activity of tritium in tap water, its detection requires a high-efficiency LSC with the lowest minimum detectable activity (MDA). Low-level tritium analysis in tap water were performed in two LSC models using conventional distillation techniques. The optimal conditions with the lowest MDAs were applied to determine the tritium concentration in the tap water distributed from two main sources located in the Bangkok metropolitan region: Bang Khen and Maha Sawat water treatment plants (WTPs). Twenty-six tap water samples were collected from petrol stations located around both water treatment plants. The results revealed that the amount of tritium in the tap water around the Bangkhen WTP was between 1.88-2.63 Bq/L with an average of 2.28±0.28 Bq/L, whereas those from the Maha Sawat WTP were between 2.01-2.69 Bq/L with an average of 2.44±0.26 Bq/L, which are far below the World Health Organization's (WHO) guideline limit (10,000 Bq/L) for drinking water. The annual effective dose (AED) for infants, children and adults obtained from tap water samples around the Bangkhen WTP were 0.010, 0.014, and 0.030 µSv/year, respectively, and those from the Maha Sawat WTP were 0.011, 0.015, and 0.032 µSv/year, respectively, which are far below the WHO's guideline limit (100 µSv/year). [ABSTRACT FROM AUTHOR]

A radiation biodosimeter is a measure of biological response to radiation that can help determine the exact dose received by using biological markers or radiation-damaged chromosomes using a blood sample as a surrogate tissue. Today, many researchers are interested in micro-technology known as microfluidics which is a device that deals with the theory of fluid flow in sub-millimeter sizes. This research demonstrates the design and fabrication of a microfluidic device for separation of lymphocytes from whole blood using a centrifugal technique. The device is made of a circular PMMA (Sumipex) sheet with a diameter of 90 mm and a thickness of 5 mm, consisting of 12 chambers, each a 3 mm deep hexagonal cavity with a capacity of 120 µL and a straight channel 20 mm long. Efficacy testing was performed by loading 120 µL of whole blood into a chamber and centrifuging at 3000 rpm for 5 min. A yellow layer was removed and overlaid on the Ficoll solution (1.077 g/mL) and centrifuged at the same speed. The peripheral blood mononuclear cells were then removed and stained with trypan blue before counting in the hemocytometer. The results show that the developed microfluidic device is able to separate lymphocytes efficiently, which is used as part of a radiation biodosimeter. [ABSTRACT FROM AUTHOR]

The International Atomic Energy Agency (IAEA) and Hiroshima International Council for Health Care of the Radiation-Exposed (HICARE) jointly organized two relevant workshops in Hiroshima, Japan, i.e. a Training Meeting 'Biodosimetry in the 21st century' (BIODOSE-21) on 10–14 June 2013 and a Workshop on 'Biological and internal dosimetry: recent advance and clinical applications' which took place between 17 and 21 February 2020. The main objective of the first meeting was to develop the ability of biodosimetry laboratories to use mature and novel techniques in biological dosimetry for the estimation of radiation doses received by individuals and populations. This meeting had a special focus on the Asia-Pacific region and was connected with the then on-going IAEA Coordinated Research Project (CRP) E35008 'Strengthening of "Biological dosimetry" in IAEA Member States: Improvement of current techniques and intensification of collaboration and networking among the different institutes' (2012–17). The meeting was attended by 25 participants, which included 11 lecturers. The 14 trainees for this meeting came from India, Indonesia, Japan, Malaysia, Philippines, Republic of Korea, Singapore, Thailand and Vietnam. During the meeting 13 lectures by HICARE and IAEA invited lecturers were delivered besides eight research reports presented by the IAEA CRP E35008 network centers from the Asia-Pacific region. Two laboratory exercises were also undertaken, one each at Hiroshima University and the Radiation Effects Research Foundation (RERF). The second training workshop aimed to discuss with the participants the use of mature and novel techniques in biological and internal dosimetry for the estimation of radiation effects by accidental, environmental and medical exposures. The workshop was attended by 19 participants from Indonesia, Jordan, Oman, Philippines, Singapore, Syrian Arab Republic, Thailand, UAE, USA and Yemen. The main outcome of both meetings was a review of the state-of-the-art of biodosimetry and internal dosimetry and their future perspectives in medical management. This report highlights the learning outcome of two meetings for the benefit of all stake-holders in the field of biological and internal dosimetry. [ABSTRACT FROM AUTHOR]

Physiologically relevant concentrations in biological tissue, in the in vivo, state are of the order of μmol L−1 and mmol L−1. Up to the present, mapping the major elements in the matrix and its thickness has been neglected, despite their importance for quantification of lesser and trace element concentrations. Ryan and Jamieson's dynamic analysis, statistical spectral decomposition approach, is developed to quantitatively measure ex vivo tissue sections cut using a cryomicrotome. This mitigates the problem that physical analysis methods require a vacuum environment. This approach is used to quantitatively image the major matrix elements H, C, N, and O as well as trace maps of Ca, Fe, and Zn in a tissue section of porcine intestine. This sample is selected as it exhibits a complex morphology with multiple tissue compartments (such as muscle and mucosa, as well as void areas from blood vessels, lymph ducts, sinuses crypts, and villi. In the results, it is demonstrated that different tissue types can have a different matrix composition and thickness. Using this information, quantitative maps and elemental molarities for the lesser and trace elements Ca, Fe, and Zn are obtained. [ABSTRACT FROM AUTHOR]

The in vitro dose calibration curves using conventional biological dosimetry - dicentric chromosome assay (DCA) and premature chromosome condensation (PCC) assay - were performed for the first time in Thailand for reconstruction of radiation dose in the exposed individuals. The peripheral blood lymphocyte samples from healthy donors were irradiated with 137 Cs source at a dose rate of 0.652 Gy/min to doses of 0.1, 0.25, 0.5, 0.75, 1, 2, 3, 4, and 5 Gy for DCA technique, and 5, 10, 15, 20, and 25 Gy for PCC technique. The blood samples were cultured and processed following the standard procedure as prescribed in the International Atomic Energy Agency report with slight modifications. The yield of dicentrics with dose from at least 1000 metaphases or 100 dicentrics was fitted to a linear quadratic model using Chromosome Aberration Calculation Software (CABAS, version 2.0) whereas those of PCC rings with dose from 100 rings was fitted to a linear quadratic equation at doses from 0 to 15 Gy. These curves will be useful for in vitro dose reconstruction and can support the preparedness for overexposure to radiation among public or occupational workers and eventual radiological accident in Thailand., Competing Interests: There are no conflicts of interest.