RESUMEN
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.