Step Up Research on Whether PFAS Causes Cancer in Humans

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The Ministry of the Environment presented a draft report to a panel of experts on PFAS, a group of synthetic chemicals known to be carcinogenic. It would require water suppliers to conduct water quality tests and take measures if the levels exceed the standards under the Water Supply Act. The panel has now approved the draft, which will be finalized after consultation with the Cabinet Office's Food Safety Commission.

Concerns about PFAS must be alleviated for Japan to continue being a country where people can drink tap water safely. To that end, the legal basis for quality monitoring and regulation of PFAS should be clarified promptly. Thereafter, inspections and improvements must be conducted without fail.

What Are PFAS?

PFAS is a general term for organic fluorine compounds, of which there are thought to be more than 10,000 varieties. The water quality standard is set at 50 nanograms per liter (nano = one billionth) for the combined total of the representative substances PFOA and PFOS.

That is the same as the current interim target. Regular inspections are conducted once every three months. Now, however, there are no real penalties even if the interim target is exceeded. The water supplier in question is only required to make an effort to improve the situation.

In the town of Kibichuo, Okayama Prefecture, elevated levels of PFAS were detected in drinking water. That led Japan to conduct the first publicly-funded mass blood concentration test. Results showed that the PFAS level exceeded the standard in more than 80% of cases. (The tests applied a standard set by an American academic institution used as the benchmark in the United States.)

However, the Japanese government has not set a standard for blood levels, citing "insufficient knowledge." American academic institutions have also stated that exceeding the recommended limit does not affect health. Therefore, it is difficult to scientifically evaluate the significance of test results at this point.

An International Drinking Water Concern

At a press conference on January 28, Deputy Chief Cabinet Secretary Kazuhiko Aoki said the government was "not considering" providing support for local governments to conduct blood tests.

However, PFAS has become an international issue. The International Agency for Research on Cancer, a part of the World Health Organization, has warned about possible adverse health effects caused by PBFAS. In 2023, IARC classified perfluorooctanoic acid (PFOA) as "carcinogenic to humans." They listed it at the highest level on a four-level carcinogenicity scale. They also identified perfluorooctanesulfonic acid (PFOS) as "probably carcinogenic to humans." Nevertheless, to date, they noted, evidence remains "limited" or "insufficient."

In Japan, the Food Safety Commission concluded in an assessment that evidence concerning PFAS "is not sufficiently reliable to clearly determine it to be carcinogenic to humans."

We must be careful not to overreact or cause turmoil among the general public. Nonetheless, we must further strengthen the ministry's pilot surveys and environmental monitoring to alleviate concerns. Monitoring and research on PFAS should be accelerated in various regions. The central government and local governments must also provide accurate information to the public in an easy-to-understand manner.