The results of Japan’s largest-scale PFAS epidemiological survey, conducted in Osaka, have been released.

45% of the 1,190 people tested in Settsu City, Osaka Prefecture, location of the Daikin Yodogawa Plant, had levels that “require treatment” according to the guidance adopted by the U.S. government.

Across the prefecture, 38.5% exceeded the standard, with concentrations higher the closer to Settsu City.

While contamination of PFOS, which is used at U.S. military bases, has become a problem in Tokyo and Okinawa, it has come to light that residents in Osaka are exposed to PFOA, which was manufactured by Daikin.

The International Agency for Research on Cancer (IARC), a cancer-specialized agency of the World Health Organization (WHO), has determined that PFOA is “carcinogenic,” classifying it two levels above PFOS, which is “possibly carcinogenic.”

Settsu residents are 4.5 times the national average

The “Osaka PFAS Contamination and Health Study Group,” consisting of doctors, scientists, and citizens, held a press conference in Osaka City on August 11, 2024.

The results of the blood test analysis that has been conducted since September 2023 are announced. This is the largest PFAS epidemiological study in Japan, with 1,190 participants aged 15 to 93 who live or work in Osaka Prefecture.

Koji Harada, associate professor at Kyoto University, and Akio Koizumi, professor emeritus, who analyzed the test, reported the results.

The blood concentrations of six PFAS, including PFOA and PFOS, which are known to be highly toxic and persistent, were measured. The results revealed that PFOA levels were particularly high in residents living near the Daikin Yodogawa Plant. The concentrations were as follows:

National average in a survey by the Ministry of the Environment: 2.2 ng/mL

 

Average for Settsu City residents (183 people): 9.8 ng/mL (4.5 times the national average)

 

Average of Settsu City and Higashiyodogawa Ward residents (311 people): 8.1 ng/mL (3.7 times the national average)

How should we evaluate these figures? What Harada and Koizumi presented are the standards that each country adopts in light of the dangers of PFAS.

The German Environment Agency has developed a standard called “HBM-II,” which establishes a PFOA standard value of 10 ng/mL as a guideline for preventing health risks based on human health surveys (epidemiologic studies).

Clinical guidance from the National Academies of Sciences, Engineering, and Medicine, which is adopted by the U.S. government, warns that patients with combined levels of 7 PFAS, including PFOA of “20 ng/mL or higher” “require treatment considering the risk of kidney cancer, testicular cancer, ulcerative colitis, and thyroid disease.”

According to these standards, 17% of Settsu and Higashiyodogawa residents exceed the German Environment Agency’s standard, and 45% exceed the U.S. Academy’s standard.

Harada said, “Normally (in areas with no PFOA contamination), levels do not exceed 10 ng/mL,” and assessed that “PFOA contamination in Settsu City is striking.” Koizumi said, “There is no doubt that Settsu City and Higashiyodogawa Ward have statistically high levels.”

Exposure from agricultural crops around the Yodogawa Plant

To understand how residents were ingesting PFOA, Koizumi and Harada also researched the lifestyles of the blood test participants, such as their use of tap water and water purifiers, and how often they consumed agricultural crops and fish.

As they continued his analysis, Koizumi noticed a certain characteristic.

In Settsu City and Higashiyodogawa Ward, Osaka City, the more locally grown agricultural products people consumed, the higher their blood levels of PFOA were.

Average of people who eat locally grown vegetables: 10.9 ng/mL

 

Average of people who don’t eat locally grown vegetables: 7.1 ng/mL

Koizumi has been investigating the fields around the Yodogawa Plant since a 2020 Ministry of the Environment survey revealed that Settsu City’s groundwater had the highest concentration of PFOA in the country. High levels of PFOA have been found in vegetables.

In response to the results of this survey, Koizumi made the following assessment:

“In Settsu City and Higashiyodogawa Ward, Osaka City, consumption of locally grown vegetables increases exposure.”

30% of residents in the prefecture “require treatment” by the standards of the U.S. Academy of Sciences

Both Koizumi and Harada had predicted high blood levels among residents living near the Yodogawa Plant, as previous blood tests had shown similar results.

Examination date	Number of people tested (Settsu City residents)	Examination results
July 10, 2020	1	High concentration
September 30, 202	5	4 people have high concentration
October 23, 2021	9	All of 9 people have high concentration
June 5, 2022	11	7 people have high concentration
September 27, 2022	8	All of 8 people have high concentration

 

What surprised them was that the concentration in Osaka Prefecture as a whole was 3 times higher than the national average.

The national average in a Ministry of the Environment survey: 2.2 ng/mL

 

Average of Osaka Prefecture (1,190 people): 6.7 ng/mL (3 times the national average)

Here are the results compared with other nations’ standards:

German Environment Agency standard: exceed by 8.5%

 

The U.S. Academy standard: exceed by 30.7%

When Osaka Prefecture was divided into five regions (which also includes parts of Nara Prefecture, Hyogo Prefecture, and Kyoto Prefecture), the area closer to the Daikin Yodogawa Plant had higher concentrations. According to Koizumi, this is likely due to the widespread contamination of soil from underground water at the plant, but further research is needed to determine the cause.

Lawsuit against Daikin “considered in the future”

The largest epidemiological study in Japan has revealed the impact of PFOA contamination caused by Daikin.

The study group’s secretary-general, Fumio Nagase, stated that the results of the study will be used to advocate for action from Osaka Prefecture and Settsu City.

So what will they do with Daikin? Further investigation is required into the health effects, but some residents have already been unable to use their own fields and wells.

Since Daikin will not voluntarily offer compensation to the residents, the residents have no choice but to take action.

I asked about the possibility of filing a lawsuit against Daikin. Secretary General Nagase responded as follows:

“Some of the members of the group are lawyers. We will consider filing a lawsuit in the future.”

Investigation on Daikin employee exposure continues

There are three other citizens not included in this report.

They were former Daikin employees. Three of them had extremely high blood levels. The highest was 596.6 ng/mL (271 times the national average). The other two also had levels over 100 ng/mL (more than 45 times the national average).

The reason for this is thought to be that they worked with PFOA and inhaled it on a daily basis. These three individuals were excluded from the calculation because they would have a large impact on the statistics.

In a confidential Daikin document obtained by Tansa (dated September 18, 2000), Daikin itself wrote the following about employees’ exposure to high levels of PFOA on its production lines:

“In particular, where the powder is taken out, the measured concentrations are high, and exposure will be an issue.”

Koizumi and Harada also said they would “continue to investigate” employee exposure to PFOA.

“The PFAS blood collection site is here.”

(Originally published in Japanese on August 11, 2024. Translation by Mana Shibata.)

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