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Toxins found in water sources near US bases in Okinawa

A spring, known as Mendakarihiga, where high levels of toxic chemicals have been detected, is seen in this file photo taken in the Okinawa Prefecture city of Ginowan on March 1, 2019. (Mainichi/Tamami Kawakami)

NAHA -- Two chemical compounds that may increase the risk of cancer have been found in high concentrations in water sources near United States military bases in the southernmost prefecture of Okinawa, the prefectural government has announced.

Surveys found high concentrations of perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA). The Okinawa Prefectural Government believes there is a high probability that the sources of the toxins are the military bases.

The U.S. military, however, has not heeded the prefectural government's requests for on-site inspections, and thus the causes of the contamination have gone unconfirmed.

Due to their ability to repel water and oil, PFOS and PFOA have been used for a variety of purposes, including in foam fire extinguishing agents used at airports. While there are no numerical criteria in Japan for what amount of the chemicals is permissible in tap water, the U.S. Environmental Protection Agency (EPA) established in 2016 health advisory levels at 70 parts per trillion in order "to provide Americans, including the most sensitive populations, with a margin of protection from a lifetime of exposure to PFOA and PFOS from drinking water."

In the past, the U.S. military has not supplied information necessary to deal with environmental problems to local authorities, which has forced the prefectural government to go through freedom of information procedures to obtain information on incidents in which toxic substances have leaked.

In a survey that the Okinawa Prefectural Government carried out in 2015, it found a maximum of 1,379 nanograms of PFOS and PFOA per liter of water in the Dakujaku River that runs through U.S. Kadena Air Base, which spans the towns of Kadena and Chatan. Furthermore, a maximum 120 nanograms of the chemicals were detected at the Chatan water treatment facility, which takes in water from rivers near the base to supply tap water. Facing these figures, the prefectural government spent 170 million yen to replace granular activated carbon at the water treatment facility that is used in the water purification process.

Some 70% of all U.S. bases in Japan are located in Okinawa Prefecture. A prefecture-wide survey that began in August 2016 found high levels of the chemicals in a water source near U.S. Marine Corps Air Station Futenma in the southern Okinawa Prefecture city of Ginowan. In a survey conducted in the summer of 2018, water at six out of 16 sites near the Futenma base had contamination levels that surpassed the health advisory levels established by the EPA. The highest contamination levels were found at the spring Chunnaga, where 2,000 nanograms of the toxic chemicals, or 28 times the EPA's health advisory levels, were detected.

Masami Kawamura, head of the Informed-Public Project, an Okinawa-based environmental survey organization whose mission is to analyze negotiations between the prefectural government and the U.S. military, commented, "The Japanese government emphasizes the relationship of trust with the U.S., but in reality, (Okinawa) Prefecture's requests (to conduct on-site inspections) have been treated lightly.

"Despite this being an issue that has direct bearing on the lives of residents, the necessary information has not been made available."

When asked by the Mainichi Shimbun what it thinks about the Okinawa Prefectural Government's argument that it is highly likely that the U.S. military bases are the source of contamination, the public relations department of U.S. Forces Japan (USFJ) did not directly address the question. It responded, however, that Japan currently does not have any environmental standards on PFOS and PFOA exposure levels, and that the USFJ hoped to work on this problem together with the Japanese government in a systemized way. The military's PR department also noted that it was in the process of switching to foam fire extinguishing agents that did not contain PFOS and contained only minute amounts of PFOA, but did not comment on whether the use of the chemicals had any causal relationship with the contamination of Okinawa's water sources.

In June, the Okinawa Prefectural Government requested that then Defense Minister Takeshi Iwaya seek permission from the U.S. military for the prefectural authorities to conduct on-site inspections inside the bases. When asked by the Mainichi about the request, a Defense Ministry official said, "We have passed on the request from the prefectural government to the U.S. side, and will continue to make arrangements as we work to further our collaboration."

In the Oyama district of Ginowan, there is a spring downstream known as Mendakarihiga across a national road from the Futenma base, which has a long history among the people and culture of the region. The area around the base is a plateau of Ryukyu limestone that allows for the easy passage of water. The water that has flowed downstream gathers underground and emerges as the spring. The taro fields local to the area have reaped the benefits of this water.

But a prefectural survey carried out in the summer of last year detected 650 nanograms of PFOS and PFOA per liter of water, while another survey conducted in January of this year detected 770 nanograms of the chemicals per liter of water. The prefectural government has been calling on local residents not to drink the spring water -- water that was, in the prewar period, used in everyday life, which welled up even during droughts, and which was used to wash children when they were delivered.

Since tap water systems were installed in the postwar period, the spring water has been used for agricultural purposes. After PFOS and PFOA were detected in the spring water, the prefectural government tested agricultural products that were grown using the water, but samples all tested negative for both chemicals. An 83-year-old man who for generations has farmed taro in the area worries about harmful rumors that could impact taro consumption, but also about the possibility that the water could be unsafe. But right next to the taro field, migratory birds were resting their wings, and there was a river where shrimp and crab lived, and fireflies could be seen. "As long as these animals are around, I guess we're OK," the man said. "I hope this nature stays here forever."

(Japanese original by Tamami Kawakami, City News Department)

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