History and Current Status of Dioxin Pollution in the Tama River

History and Current Status of Dioxin Pollution in the Tama River
In the 1990s, highly poisonous 2378-tetrachlorodioxin was detected at high concentrations in the bottom sediment of the Tama River, and its main sources were estimated to be waste incineration plants in Kawasaki City and Ota Ward, Tokyo, and industrial effluent in the upstream area. 2010s saw technological improvements at waste incineration facilities and progress in effluent regulations, and the concentration of dioxin in the bottom sediment dropped to an average 10 picogram TEQ/g on average. Furthermore, by the 2020s, through the use of exhaust gas treatment technology and alternative fuels, dioxin emissions for the entire Tokyo metropolitan area were reduced to 5 grams TEQ/year. Although the environment is improving thanks to the cooperation of residents and businesses, improvement of some high-concentration points and long-term measures remain challenges. The case of the Tama River is considered a model case for improving the water environment.