Distribution of gamma radiation dose rate related with natural radionuclides in all of Vietnam and radiological risk assessment of the built-up environment.

A built-up environment utilizes building materials containing natural radionuclides that will change radiological risks. While radiological risks have been estimated from the activity concentrations of natural radionuclides in soil, it is important to evaluate the changes of these risks for the built-up environment using these building materials. Based on the direct measurements of absorbed dose rate in air and calculation of absorbed dose rate in air from activity concentrations in soil for all of Vietnam which has undergone significant economic growth in recent decades, the changes of absorbed dose rate in air and radiological risks before and after construction of many artificial structures were investigated. The results showed that the absorbed dose rates in air were clearly changed by the urbanization, and the difference ratio for all of Vietnam ranged from 0.5 to 2.1, meaning that the artificial structures have been acting as shielding materials to terrestrial gamma-rays or radiation sources. However, changes in annual effective dose in the built-up environment were small, and there was no new radiation risk from the built-up environment for Vietnam.

Impact on gadolinium anomaly in river waters in Tokyo related to the increased number of MRI devices in use.

The Gd-based contrast agents utilized in magnetic resonance imaging are difficult to remove by usual sewage treatment technology, and they enter rivers in the discharges from waste water treatment plants. Gd anomaly in rivers has been considered depends on used amount of Gd-based contrast agents. In this study, variation of Gd anomaly in rivers of Tokyo was determined by comparisons to previously reported values. The range of anthropogenic Gd was 0.1-138.8 ppt with an average value of 35.5 ppt (n = 40); in particular, the anthropogenic Gd was significantly changed depending on the location of the waste water treatment plants, and the measurement revealed significant increases in the Gd anomaly in the range of 5.0-6.6 times compared to data obtained 22 years ago. This study highlights the necessary of continuous research in setting new public policies for medical practices.