TOKYO — Residents living near a U.S. military base in western Tokyo have been having deepening concerns about their health after a recent local study found many of them have excessive amounts of harmful substances, dubbed “forever chemicals,” in their bloodstream.

After the government revealed last month that leakages had occurred from foam extinguishers containing polyfluoroalkyl substances, known as PFAS, over a decade ago at Yokota Air Base, locals have grown increasingly suspicious that the incident could be related to their blood test results.

Yukio Negiyama, who lives in Hino in western Tokyo’s Tama area, where the military facilities are located, is one of the many locals demanding detailed inspections and more information.

“Although I cannot swear by it, I strongly suspect that the Yokota base has a connection to the outcomes of the blood tests,” he said.

PFAS is a general term for a group of artificial chemicals that include PFOS, or perfluorooctanesulfonic acid, and PFOA, or perfluorooctanoic acid. They are described as persistent organic pollutants, or forever chemicals, because they are nearly indestructible.

Resistant to oil and water while tolerant of heat, PFAS chemicals have been used for a wide range of applications, including nonstick frying pans, fire extinguishers and the production of semiconductors.

But given they do not degrade over time unlike most other chemicals, they can accumulate in the environment and the human body, with American and European researchers pointing out in recent years that high exposure to PFAS chemicals increases the risk of developing kidney and testicular cancers and high cholesterol.
International efforts, such as those made by the European Union, have been underway to prohibit or limit the usage and production of the chemicals, and rules have been tightened regarding their management and disposal.

Japan banned the manufacture and import of PFOS substances across the board in 2018, as well as those categorized as PFOA in 2021.

Meanwhile, following the detection of a high concentration of PFOS and PFOA substances in water sources in the Tama area such as wells, a local civil group began conducting blood tests on 650 residents from 27 municipalities in November last year. The results, released in June, found high PFAS levels, defined as surpassing 20 nanograms per milliliter in someone’s blood sample, in 335 people, with the highest at 124.5 ng/ml.