PFAS chemicals detected in sewage sludge at 34 locations across Japan
The study supports the view that the chemicals have spread nationwide. The Japanese government is promoting the use of sludge as fertilizer, but has not set guideline values for the amount of PFAS in sludge byproducts.
PFAS is a general term for a group of over 10,000 artificial chemicals that include PFOS, or perfluorooctanesulfonic acid, and PFOA, or perfluorooctanoic acid.
Known as forever chemicals because they are highly resistant to breakdown and accumulate in soil and water as environmental pollutants, PFAS are used in various products such as firefighting foam and nonstick cookware coatings.
"There is a possibility that PFOS, which is feared to pose health damage, is contained in sewage sludge in Japan in general," said Kazuyuki Oshita, associate professor at Kyoto University, who analyzed the findings.
"It is desirable that the accumulation of data will lead to the creation of a guideline in the future," Oshita said.
Various surveys in Japan have recently shown PFAS contamination in tap water and rivers and around factories, U.S. military bases, and Japan Self-Defense Forces facilities, raising concerns among the public given experts' concern over possible health risks.
In line with the Stockholm Convention on Persistent Organic Pollutants, Japan bans in principle the manufacturing and import of PFOS, PFOA as well as PFHxS, another type of PFAS.
The Kyoto University team analyzed sewage sludge at 34 treatment plants for 30 types of PFAS, including PFOS, from Hokkaido in northern Japan to Okinawa in southern Japan.
The median value for PFOS content was 5.1 nanograms per gram, while the highest was 69 nanograms. PFOS was confirmed at 33 out of 34 locations, while it had the highest concentration in 21 locations that detected PFAS chemicals.
The latest survey came as the farm ministry aims to double the usage of fertilizers derived from sewage sludge by 2030 from the 2021 level as the state seeks to increase the rate of domestically-sourced fertilizers.
"The quantity of PFAS is extremely small at an undetectable level. There is no problem using it," said a ministry official. The Ministry of Agriculture, Forestry and Fisheries released data last year based on its study of 86 samples of such fertilizers.
Abroad, regulations over PFAS are gaining traction, with the U.S. Environmental Protection Agency in January releasing a preliminary human health toxicity assessment over PFAS in sewage sludge applied as soil conditioner or fertilizer.
It said even a low concentration of the chemicals could pose a health risk to farmers and surrounding residents.
For PFOA and PFOS in tap water, the Japanese government will from next April regulate the levels. Utility operators need to improve water quality if the concentration of the chemicals is found to exceed 50 nanograms per liter.
© KYODO
Hashtags
Try Our AI Features
Explore what Daily8 AI can do for you:
Comments
No comments yet...
Related Articles
The Mainichi
an hour ago
- The Mainichi
Golden living statues in Osaka raise awareness about hazard of long periods in same posture
OSAKA -- Golden human statues appeared in an underground street in Osaka's Umeda district on Aug. 18 to raise awareness about how remaining in the same posture for long periods can lead to shoulder pain and other issues. The exhibition "Chokoku na Shisei Ten" -- a pun on the Japanese words "chokoku" (sculpture) and "cho koku" (super tough) -- began in the underground passage in front of Osaka Station in the city's Kita Ward. It features performers who paint their faces and costumes to mimic statues or sculptures. Additional performances are scheduled for Aug. 23 and 24. The exhibition promotes pain relief medications from the pharmaceutical company SSP Co., highlighting they not only alleviate headaches and menstrual pain but also shoulder pain. The statue performers re-create everyday postures that contribute to shoulder pain, such as using smartphones while commuting and doing desk work, while others include sitting on the ground to watch fireworks and standing over grills to make "takoyaki" octopus balls -- a well-known Osaka street food. When visitors insert coins into a nearby box, the performers come to life, rotating their shoulders or stretching. Statue performances like these are a form of street art said to have originated in France and are a familiar sight in tourist areas across Europe and the United States. The event features five professional statue performers, mainly from western Japan's Kansai region. Passersby were surprised by the sudden movements of the performers, often smiling and taking photos with their smartphones. The event will be held four times each on Aug. 23 and 24, with each session lasting one hour. (Japanese original and video by Takao Kitamura, Osaka Photo and Video Department)
Asahi Shimbun
an hour ago
- Asahi Shimbun
Mystery behind clapping sound finally comes out loud and clear
Voters applaud as a candidate running in the Upper House election delivers a speech in Fukuoka in July. A round of applause is a routine gesture, but the science behind the sound remained a mystery until recently. (Maho Fukui) Researchers deserve a round of applause for uncovering the science behind the acoustics produced from hand clapping that had not been clearly understood until recently. The daily gesture that people make across cultures conveys support and sympathy, as well as expressing excitement and joy among other emotions. Clapping is also used to move the hands to the beat while listening to music. But there's more to the sound than meets the ear. X-MEN SUPERVILLAIN INSPIRED STUDY A team of scientists from Cornell University and other U.S. universities now report that the percussive sound produced is not simply from the collision of palms, contrary to conventional wisdom. The sound emanates from a jet of air rapidly strewn out from the narrow gap between the index finger and thumb when the hands meet, in line with the Helmholtz resonance theory in physics. The Helmholtz resonator is a phenomenon in which a certain sound is heard loudly when air in a container with an open neck vibrates at a natural specific frequency due to the springiness of the air inside, which repeats the cycle of compression and decompression. The frequency of sound is variable, depending on such factors as the volume of the container and the size of the opening. In a hand clap, the cavity between the palms corresponds to the container and the gap between the index finger and thumb to the opening of the neck. A similar, well-known example of the theory is the tone created by blowing air across the mouth of an empty bottle. One reason that the mechanism behind a clap had been a mystery for a long time is this sound generation is a 'complex and unsteady process involving soft-body collision and acoustic wave propagation,' according to a research paper published recently in the online edition of the U.S. scientific journal Physical Review Research. The research team conducted experiments involving human hands and silicone replicas of human hands to unravel how the sound of clapping is produced. Sunghwan Jung, one of the authors and professor of biological and environmental engineering with Cornell University, said he was inspired for the experiment on hand clapping after watching the movie 'X-Men: The Last Stand.' In the 2006 Hollywood blockbuster, a mutant supervillain named Arclight emits powerful shock waves against her enemies when she claps her hands. 'We knew that we heard the sound from hand clapping,' Jung said in an email interview with The Asahi Shimbun. 'However, it was not clear what frequency and how long this sound will propagate.' AIR RESONANCE THEORY OFFERS CLUE The experiment got under way in 2022, with Akihito Kiyama, a Japanese scientist who was working as a postdoctoral researcher at Jung's lab, leading the project. Kiyama was selected because of his experience in using audio and video recordings from his previous study on the relationships between bubbles forming and the cracking sounds produced when wet bamboo chopsticks were dipped in hot oil. As for hand clapping, there was a prior study that suggested, though without concrete evidence, that the clapping sound might be explained by the Helmholtz resonator model. However, Kiyama, now an associate professor of mechanical systems engineering with Saitama University in Japan, recalled being initially skeptical if the findings of their experiment would confirm the Helmholtz resonance theory. 'I was not really sure because hand claps involved soft materials like humans' hands,' he said. The scientists studied a person's clapping motion and sound, changes in air pressure in hand cavity and air flow by recording them simultaneously with a high-speed camera, microphone, signal amplifier and pressure sensor. The 10 participants enlisted for the experiment clapped their hands in three hand configurations--cupped, palm-palm and palm-finger. In addition, silicone replicas of hands were also used for analysis. The study found that little sound was produced at the very moment when the hands meet, but sound was generated when a jet of air spewed out of an opening between the index finger and thumb. The researchers also confirmed that the frequencies of the recorded sound matched figures that were predicted based on the Helmholtz resonator theory. 'BEAUTY OF PHYSICS' Yicong Fu, a lead author and a Cornell University Ph.D. student who succeeded Kiyama in the experiment, said he found the project fascinating because of the interdisciplinary effort that went into it. 'What got me interested in it personally was the multi-faceted physics involved in it,' he said in his email. 'There are fluid flow, sound generation, tissue mechanics, dynamical systems, etc. I felt that I could synthesize my knowledge from various courses together to understand this complex physical process. 'Although it's challenging, I think it was very fun to see how so many different subjects are connected to each other.' Researchers noted that it took time to deduce why clapping also included sound that cannot be explained by the Helmholtz resonance model alone. Fu and his colleagues finally unraveled the science behind the sound of clapping three years after the experiment began. To Fu, the project turned out to be a fresh reminder of 'the beauty of physics.' 'I was very amazed and humbled to see such an elegant theory is powerful enough to capture the frequency of this very dynamic and complex phenomenon,' he said. 'It was really a time for me to appreciate the beauty of physics--it simplifies complex systems into an easy core that's fathomable to everybody.' He added that undertaking an experiment out of genuine curiosity can go a long way. 'I personally think this curiosity-driven research really shows the public that we should pay attention to our everyday lives, because when we think deeply, there are so many new things to learn,' he said.
3 hours ago
Ishiba Vows Aid to Nurture AI Experts in Africa at TICAD 9
Yokohama, Aug. 21 (Jiji Press)--Japan will work on nurturing experts in artificial intelligence to help African countries to achieve economic growth and solve social problems, Japanese Prime Minister Shigeru Ishiba said Thursday at the ongoing Ninth Tokyo International Conference on African Development, or TICAD 9. "The development of human resources in new fields such as digital-related industries, including AI, and creative industries will be one of the foundations for accelerating future growth," Ishiba said at a public-private business dialogue session of the summit-level conference running for three days through Friday in Yokohama in Kanagawa Prefecture, south of Tokyo. "Japan will help Africa diversify its economy" by developing 300,000 workers across the continent in the next three years, the prime minister, co-chair of the conference, added. The Japanese government aims to nurture 30,000 AI experts through the Japan Africa Co-Creation for Industry, a framework set up by the Japanese industry ministry to enhance cooperation between Japanese companies and African startups. Japan will also work with local universities and the U.N. Development Program to help trained AI experts start their own businesses or find jobs. [Copyright The Jiji Press, Ltd.]
