Japanese authorities conducted an on-site inspection over contaminated water leakage at the US military's Yokota Air Base in western Tokyo on December 20.

According to the Tokyo Metropolitan Government, about 50,000 liters of water contaminated with substances including the chemical PFAS leaked out from the facility's fire training area on August 30.

Officials from Japan's central government and the prefectural and municipal governments where the base is located took part in the inspection.

They looked at the fire training area and received explanations from US officials.

In a groundwater survey conducted by the metropolitan government across Tokyo, there were some locations where PFAS levels exceeded the provisional national limit.

While PFAS is said to have toxic effects on the human body, the Food Safety Commission of Japan has said there is insufficient information regarding its potential health effects.