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Toxin blood levels up to 14 times national average among Okinawa residents near US bases

This Sept. 5, 2022, image shows the spring Chunnaga, which is located near a U.S. military base in Ginowan, Okinawa Prefecture, and where PFOS and other toxic substances exceeding provisional standard levels were detected. (Mainichi/Hiroya Miyagi)

NAHA -- Blood levels of potentially cancer-causing organic fluorine compounds among residents of Okinawa Prefecture, where toxic chemicals have been detected in high concentration in rivers and springs near U.S. military bases, were this year found to be up to 14 times the nationwide average.

    A citizens' group, consisting of an environmental scientist and others in Okinawa Prefecture, conducted the study in June and July, with the cooperation of Koji Harada, associate professor of environmental hygienics at Kyoto University. Following the survey, the group has called for the national and prefectural governments to carry out an on-site inspection of military bases as well as an extensive epidemiological investigation, in order to specify the causes and uncover health risks.

    In the study, blood samples were collected from a total of 387 people aged 18 or older in the five municipalities of Okinawa, Ginowan, Kadena, Kin and Chatan, which host U.S. military bases, and Ogimi, a base-free village located in the northern part of the main island, to compare results.

    The study found that PFHxS, one type of organic fluorine compound, was found at a concentration of 1.7 nanograms per milliliter among residents of Ogimi, which saw the lowest average figure. Meanwhile, 14.3 nanograms per milliliter were detected in residents of the town of Kin, which recorded high levels. Blood levels of the chemical compound recorded in the Okinawa municipalities were between 1.7 and 14.3 times the national average from the monitoring survey conducted by the Ministry of the Environment in fiscal 2021.

    Members of a citizens' group announce survey findings in the city of Naha on Oct. 15, 2022. (Mainichi/Hiroshi Higa)

    Blood levels of perfluorooctanesulfonic acid (PFOS) were between 1.5 and 3.1 times the national average, while those of perfluorooctanoic acid (PFOA) were between 0.8 and 3.0 times the nationwide average. As the blood concentration of chemicals was relatively low among residents of Ogimi, where there are no military bases, the citizens' group concluded, "It is suspected that U.S. bases, where foam extinguishing agents containing PFAS were used, are the source of contamination."

    Japan has no standard figure for blood levels of organic fluorine compounds. According to the citizens' group, Germany has set control target figures of 20 nanograms per milliliter for PFOS and 10 nanograms per milliliter for PFOA, as a general rule. If these figures are exceeded, administrative bodies are required to take emergency measures to reduce the substances out of concerns for health risks.

    In the recent survey in Okinawa, a total of 27 people exceeded these figures. Furthermore, there was a tendency for blood levels to be high among people who drank tap water, men, and elderly people, and the group estimated that menstrual bleeding and the accumulation of toxic substances in the body were also factors influencing blood levels.

    In Okinawa Prefecture, high levels of organic fluorine compounds have been detected in rivers and springs near military bases on a daily basis, and the prefectural government has been asking if it can conduct on-site inspections at military bases. However, the right to administer bases belongs to the U.S. military, under the Japan-U.S. Status of Forces Agreement, and it has not responded to investigation requests, excluding accidents that are clearly a case of leakage.

    (Japanese original by Hiroshi Higa, Naha Bureau)

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