Yokota Air Base is home to the 374th Airlift Wing, 5th Air Force and U.S. Forces Japan in western Tokyo. (Seth Robson/Stars and Stripes)
YOKOTA AIR BASE, Japan — Local authorities in cities surrounding this base in western Tokyo were not told for more than a month that thousands of gallons of water, likely tainted with toxic chemicals, spilled off the installation this summer.
A short burst of heavy rains on Aug. 30 caused approximately 12,640 gallons of water to overflow from Yokota’s fire training area onto an asphalt surface and eventually into a stormwater drainage system, according to an email Thursday from Capt. Emma Quirk, spokeswoman for Yokota’s 374th Airlift Wing.
The water probably contained residual amounts of aqueous film forming foam, she said. The foam is a firefighting material that contains PFAS, a class of chemicals with suspected toxic properties.
The foam is no longer in use at Yokota and the Air Force has moved to replace fire-suppression systems at bases in Japan with materials other than PFAS.
PFAS, a manufactured compound in many household products, from stainproof and waterproof fabric to nonstick cookware, is linked to an increased risk of certain tumors of the liver, testicles, breasts and pancreas, according to the American Cancer Society.
“Many Tokyo residents are concerned about the health effects of PFOS … and these concerns need to be alleviated as soon as possible,” said a letter from the Tokyo Metropolitan Government and six municipalities to Japan’s defense ministry and North Kanto Defense Bureau dated Oct. 3.
The six municipalities are the cities of Akishima, Fussa, Hamura, Musashimurayama and Tachikawa and the town of Mizuho.
PFOS and PFOA are two components of PFAS considered toxic and sometimes called “forever chemicals.” The U.S. Environmental Protection Agency in June said no level of PFAS is safe in drinking water. The synthetic compounds accumulate in the body over time, according to the EPA.
The North Kanto Defense Bureau, an arm of Japan’s Ministry of Defense, notified the municipalities about the spill on Oct. 3, according to a post on the metropolitan government’s website the next day.
The letter took issue with the delay in notifying local governments.
“More than a month has passed since the leak reported this time happened, and the fact that the information was not provided promptly leads to distrust of residents living near the base and it is extremely regrettable,” the letter stated.
The letter didn’t assign blame for the late notice. Neither the Air Force’s 374TH Airlift Wing nor Japan’s Defense Ministry responded to phone messages and email queries Thursday about the delay.
The letter asked Japan’s government for more information about the spill, including where the water flowed, why contaminated water was stored on base and what preventative measures will be taken.
They also asked Japan’s government to take responsibility for any fallout from the spill and to cooperate with local officials if they see a need to conduct a survey on base, the letter stated.
Between 2010 and 2022, the U.S. military reported seven PFAS-tainted spills or leaks to Japan’s Ministry of Defense, which in turn notified local governments, the Tokyo Shimbun reported July 10.
About 167 gallons of liquid containing high levels of PFAS spilled at the Yokota Community Center’s receiving dock on Jan. 25, 2023. The center houses the base commissary and exchange. However, the spill did not escape the base, the newspaper reported, citing unnamed officials.
The assessment of the August incident is complex and ongoing, but Japan’s government was notified once officials were certain the water flowed off base, Quirk said.
“Installation officials immediately began on-site assessments to track the route of the spill, volume of water and likely discharge points, and those studies continue,” she said. “The 374th Airlift Wing is committed to being good stewards of the environment and protecting the health of our personnel, their families, and the communities that surround us.”
