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Toxic water likely discharged into Yokosuka port near Tokyo from US naval base

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 government of this east Japan city announced on July 1 that drainage water contaminated with chemical compounds suspected to cause cancer, such as perfluorooctanesulfonic acid (PFOS), was likely discharged into the Port of Yokosuka from a U.S. naval base in the city.

    The announcement came after the Japanese Defense Ministry's South Kanto Defense Bureau alerted the city earlier the same day upon receiving a report from U.S. authorities.

    According to the report, foam was found in a drainage treatment facility by the sea in the eastern part of the naval base in early May. When U.S. authorities examined the drainage water, PFOS and perfluorooctanoic acid (PFOA), both organic fluorine compounds, at combined levels exceeding the Japanese government-set provisional target value of 50 nanograms per liter were detected.

    At U.S. military bases in Okinawa Prefecture and elsewhere in Japan, leakage of fire-extinguishing foam containing PFOS and other hazardous materials has raised an issue. There is a fire station near the drainage treatment facility at the Yokosuka base, but U.S. officials said the cause of the possible leaks of the substances remained unknown. As no foam is visible at the treatment facility now, U.S. authorities are set to conduct another sampling survey.

    Meanwhile, the Japanese Defense Ministry on June 30 collected seawater samples in waters near where the drainage water was discharged and is set to analyze the samples. The Yokosuka Municipal Government also urged Defense Minister Nobuo Kishi that the national government clarify whether the U.S. naval base in Yokosuka is in possession of and uses PFOS and other chemicals, and provide an explanation to people affiliated with the fishing industry.

    (Japanese original by Toshiaki Hashimoto, Yokosuka Local Bureau)

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