Level of ‘forever chemicals’ high in blood tests in Tokyo’s Tama

Koji Harada, left, an associate professor at Kyoto University Graduate School, explains the results of blood tests among residents living in Tokyo’s Tama area at a news conference in Tachikawa, western Tokyo, on June 8. (Hiromichi Fujita)

High levels of harmful organic fluorine compounds were found in blood samples of residents living in the Tama area of western Tokyo.

The leader of the study said contamination could be coming from a U.S. military base in the area.

A citizens group, which examined levels of perfluoroalkyl and polyfluoroalkyl substances (PFAS) in samples collected from 650 residents in 27 municipalities in the Tama area, announced the results on June 8.

The group said the combined amount of two typical PFAS substances–perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA)–was about 2.4 times the national average found in a survey conducted by the government.

The group entrusted the survey to Koji Harada, an associate professor of environmental hygienics at Kyoto University Graduate School.

He said “tap water is the main cause” of the high PFAS levels.

The Tama area partially uses purified groundwater for tap water, and Harada said possible sources of contamination include the U.S. Yokota Air Base, which is located in the upper river basin of the groundwater.

PFOS and PFOA, which are heat-resistant and repel water and oil, were widely used in Japan in various products, such as waterproofing treatments and foam fire-extinguishing agents.

They barely decompose in nature, giving them the nickname “forever chemicals.”

Their adverse effects on the human body have become increasingly clear, and the Japanese government currently bans the manufacturing and use of PFOS and PFOA, in principle.

The Tokyo metropolitan government has suspended water intake at 40 wells in seven cities where high concentrations of PFAS were found.

The metropolitan government in 2019 conducted a survey on PFOS and PFOA in the Tama area. It found their levels at a water purification plant in Kokubunji city were more than double the provisional target levels later set by the central government for tap water.

The citizen group solicited volunteers for blood tests across the Tama area, and 650 people aged 19 to 92 took part.

According to the group, the combined amount of PFOS and PFOA contained in 1 milliliter of blood averaged 14.6 nanograms.

The Environment Ministry found an average of 6.1 nanograms when it surveyed 119 people nationwide in 2021, although its study method could have been different.

According to Harada, in Germany, 20 nanograms of PFOS per milliliter of blood is considered a benchmark for health risks.

Fifty-five of the 650 Tama people surveyed exceeded this standard.

PFAS has been detected in various parts of Japan, including many locations around U.S. military bases and factories.

In Okinawa Prefecture, a citizens group last year tested blood samples of 387 residents living near U.S. bases and found the levels of PFOS and PFOA were 0.8 to 3.1 times the national average.

In Kanagawa Prefecture, foam fire-extinguishing agents containing PFOS leaked into a river from the Naval Air Facility Atsugi in autumn 2022.

In Osaka Prefecture, a local government investigation revealed a high concentration of PFOA in groundwater near a factory of a major manufacturer.