A local group in Iwakuni City, Yamaguchi Prefecture, Japan, held a press conference on the same day, stating that the per- and polyfluoroalkyl substances (PFAS) detected in water samples collected around the U.S. Marine Corps Air Station Iwakuni exceeded Japan's provisional national standard by about 160 times.

According to the group, on the specified date, they collected water samples from the detention pond near the base and commissioned relevant institutions for analysis. The group stated that they will request the municipal government to conduct a detailed investigation.

It is reported that per- and polyfluoroalkyl substances are difficult to degrade and accumulate in the environment and human bodies, earning them the nickname "forever chemicals." In a certain year, the International Agency for Research on Cancer, an agency under the World Health Organization, classified perfluorooctanoic acid (PFOA) as a carcinogen and perfluorooctane sulfonate (PFOS) as a probable carcinogen.

Since last year, Okinawa Prefecture, Osaka Prefecture, Tokyo Metropolis, and other areas in Japan have consecutively reported excessive levels of per- and polyfluoroalkyl substances in water bodies, with abnormal blood test results among nearby residents. As these incident areas are mostly adjacent to U.S. military bases and Japan Self-Defense Forces bases, these bases are considered potential sources of contamination.