A government survey has found that levels of potentially harmful PFAS chemicals have exceeded a provisional target at over 200 locations in rivers and underground water across Japan.



PFAS is a group of organic fluorine compounds. They include PFOS and PFOA, which are considered potentially harmful.



The government has set a provisional target for the combined amount of the two chemicals at 50 nanograms per liter of river or underground water.



It is requiring prefectures to carry out water quality tests and report the results. The environment ministry released the results for fiscal 2023 at an expert panel meeting on Friday.



The tests were conducted at 2,078 locations in rivers and underground water in 39 prefectures, and the levels of PFOS and PFOA exceeded the provisional target at 242 locations in 22 prefectures.



The highest figure was detected from underground water in Settsu City in Osaka Prefecture at 26,000 nanograms per liter, followed by underground water in Higashihiroshima City in Hiroshima Prefecture at 15,000 nanograms.



The ministry said it has taken necessary safety measures at all locations that went beyond the target. It said it has called on residents not to drink well water, and has required water service operators to dilute river water before it is put into the water supply.



The ministry said it has determined the source of the two chemicals at only four of the tested locations so far.



The expert panel also approved a plan to mandate the regular testing of tap water and change the 50 nanogram level from a provisional target to a legal standard. The ministry will revise necessary ordinance, and enforce the new standard from April 2026.