Japanese officials survey PFAS levels at US military's Yokota Air Base
PFAS is a group of organic fluorine compounds. In August last year, it was found that water containing PFAS chemicals, including PFOS and PFOA, which are considered potentially harmful, had likely leaked from the air base. Authorities have been investigating the incident.
On Wednesday, officials of the Defense Ministry, Tokyo Metropolitan Government and surrounding municipalities took samples from a reservoir on the air base to check the water quality. An accord of the Japan-US Status of Forces Agreement allows Japanese officials to survey potential environmental damage at US bases in Japan.
The Defense Ministry said more than 1.5 million liters of water containing PFOS and other chemicals remain on the air base, including in the reservoir. Ministry officials said the US side has explained that toxic substances would be removed with a decontamination system.
The officials said the water samples will be analyzed over the next two weeks. If the PFAS levels are below the government's provisional limit for tap water of 50 nanograms per liter, the treated water will be released through drains at the southwestern side of the air base.
The Defense Ministry said that it will swiftly provide detailed explanations to people in relevant municipalities.
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"Forever chemicals" found in organs of vulnerable Japanese wildcats
OSAKA - High concentrations of potentially carcinogenic PFAS "forever chemicals" have been found in Tsushima leopard cats -- a designated natural monument and vulnerable species native to a Japanese island -- researchers said Thursday. The Ehime University-led research team found the chemicals in the organs of all 21 cats examined, raising concerns about the impact of pollution on wildlife conservation across Japan. "For the protection of all wild animals, not just the Tsushima leopard cat, there must be a nationwide survey and investigations to identify the pollution source," said Kei Nomiyama, an associate professor at the university in western Japan. Tsushima leopard cats inhabit the island of Tsushima in southwestern Japan's Nagasaki Prefecture, and are listed as vulnerable on the Environment Ministry's Red List of endangered species. Their numbers have declined due to habitat loss and roadkill. The government estimates that around 100 remain, and zoos in Japan are working to breed the species. The research team received permission from the ministry to examine the livers and kidneys of 21 dead wildcats that died between 2022 and 2025, testing for 37 PFAS chemicals. Nearly all the cats had PFAS concentrations exceeding toxicity thresholds in liver cell tests, indicating potential risks to liver function, according to the study. Kidney concentrations were also considered high, it said. No significant differences based on age, sex or location were recorded. The median concentration of PFAS chemicals was eight times higher than levels found in a study of European wildcats in Germany. Experts suspect marine debris and illegal dumping as sources of the pollution, with concentrations likely accumulating through the food chain. The team also measured persistent organic pollutants, known as POPs, in 19 cats, with some showing extremely high levels of contamination. Nomiyama said there is a "strong possibility" the pollution is connected to the species' declining population. PFAS is a general term for a group of over 10,000 artificial chemicals that include PFOS, or perfluorooctanesulfonic acid, and PFOA, or perfluorooctanoic acid. Used in products such as firefighting foam and nonstick cookware coatings, PFAS are known as forever chemicals because they are highly resistant to breakdown, and accumulate in soil and water as environmental pollutants.
