Radiological impact assessment of different building material additives

In this study, samples of building material additives were analyzed for naturally occurring radioisotope activity such as uranium, radium, and radon. The radon exhalation and the annual effective doses, were also calculated. The activities of the samples, were determined using HPGe gamma spectrometry and ionization detector. The results were used to calculate dose values by using RESRAD BUILD code. The activity concentration of the samples ranges between 9–494 Bq/kg Ra-226, 1–119 Bq/kg Th-232 and 24–730 Bq/kg K-40. In conclusion the investigated samples can be used safely as building material additives as they do not pose a major risk to humans.

Transfer and bioaccumulation of 210Po from soil to water spinach (Ipomoea aquatica Forrsk.) in Vietnam

The water spinach (Ipomoea aquatica Forrsk.) is a common vegetable and a part of the staple diet in Vietnam. It has a well-known tendency for the high absorption of lead, including the radioactive isotope ²¹⁰Pb. ²¹⁰ Pb day to ²¹⁰Po, which is one of the most toxic radioactive isotopes when ingested. Currently, there are few data available on the activity concentration or transfer parameters of water spinach grown in Vietnam. To provide this data, in this study, the ²¹⁰Po activity concentrations in the soil, water and the roots, stems, and leaves of two types of spinach (grown in soil flooded with water and grown in normal soil) in Hanoi, Vietnam were determined by alpha spectrometry. The order of activity concentrations for water spinach grown in unflooded was C_stem < C_leaf < C_root, while for flooded C_stem ≈ C_root < C_leaf. The transfer factors followed a similar pattern.

210PO IN SOIL AND TOBACCO LEAVES IN QUANG XUONG, VIETNAM AND ESTIMATION OF ANNUAL EFFECTIVE DOSE TO SMOKERS

210Po is the main radiotoxic chemical in tobacco smoke and one of the primary causes of lung cancer. Investigating 210Po concentration in tobacco is important in estimating the annual effective dose (AED) due to smoking. In this study, the 210Po concentrations in tobacco leaves and soil in Quang Xuong, Vietnam were measured using a high-resolution passivated and implanted planar silicon detector. Based on these data the AEDs to smokers were estimated. The 210Po activity concentration in tobacco varied significantly from 28.7 to 254.0 mBq g-1, whereas its variation in soil was insignificant. The AED due to smoking fresh tobacco leaves in Vietnam (average 565 μSv y-1) was significantly higher than the values reported for other countries (36-361 μSv y-1).

Study of soil to plant transfer factors of 226Ra, 232Th, 40K and 137Cs in Vietnamese crops

The study of staple food products is crucial to assure public safety and provides input for predictive dose assessment models. To further this goal, the activity concentrations, transfer factors, and radiological hazards of ²²⁶Ra, ²³²Th, ⁴⁰K, and ¹³⁷Cs were studied for ten pairs of selected vegetables and soils in Tien Le near Hanoi in Vietnam. This is the first study in this area for Vietnamese vegetable samples. The ten most popular vegetables in Vietnamese diet were selected, namely choy sum, crown daisy, lettuce, cabbage, Malabar spinach, beans, sweet potato, potato, kohlrabi and carrot. The research results showed that the activity concentrations observed in vegetable crops did not present the previously reported strong correlation to those in soil. The ranges of TFs of ²²⁶Ra, ²³²Th, and ⁴⁰K were 4 × 10^-2 - 6.9 × 10^-1, 8 × 10^-2 - 9.7 × 10^-1; and 1.0 × 10⁰-1.6 × 10¹, respectively. Values for leafy vegetables and tubers exceed previous world range figures for Th and K. The soil has been evaluated for radiological hazard indices, which predict almost no risk to human health in the study area.