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US military says filters to treat toxic water at base near Tokyo Bay up and running

The front gate of the U.S. naval base in Yokosuka is seen in Kanagawa Prefecture in this May 27, 2022, file photo. (Mainichi/Toshiaki Hashimoto)

YOKOSUKA, Kanagawa -- The U.S. military has started running activated carbon filters at a drainage treatment facility at a naval base in this city southwest of Tokyo, after high levels of potentially cancer-causing chemical compounds were detected in the wastewater.

    The Yokosuka Municipal Government announced the development on Nov. 1 after the city was informed of the move by the U.S. military.

    After "abnormal foam" was found at the treatment facility on May 4 this year, perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) have been detected in the wastewater. At one point, up to 12,900 nanograms of the toxic chemicals per liter, or 258 times the Japanese government-set provisional target value of a total of 50 nanograms per liter, were found, but the sewage water had been released into Tokyo Bay untreated.

    The city of Yokosuka has been asking the Japanese government to confirm that the filters are set up as explained by the U.S. military and to let the city survey the wastewater from the base. The Yokosuka government told the U.S. military on Nov. 1 that it was crucial that the toxic chemical levels were brought down below Japanese standards.

    (Japanese original by Toshiaki Hashimoto, Yokosuka Local Bureau)

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