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Wednesday, August 12, 2026

Busseiron: Understanding the origin and evolution of a distinct branch of physics in Japan

Researchers explore the history of Bussieron’s path from a loosely defined label for matter-related research to an established discipline

Institute of Science Tokyo

Tracing the history of the name of a physics discipline — image:
This work sheds light on how a unique term for matter-related research in Japan emerged and evolved during the 20th century.
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Credit: Institute of Science Tokyo

A new etymological study shows that the terms for scientific disciplines can take shape through naming and classification as much as through theories and institutional usage, as reported by a researcher from Japan. Focusing on Busseiron, a Japanese term for the study of matter, the study traced its use across textbooks, journals, and scientific meetings. Analysis revealed how the term gradually brought together diverse matter-related research and became a durable branch of physics in Japan.

The study of matter, namely its structure, properties, and behavior, has long been one of the central pillars of modern physics. In Japan, this area of research came to be known by the distinctive term Busseiron during the 20th century, which roughly translates to “theory of the properties of matter.” Over the course of a few decades, Busseiron—also referred to in later usage as Bussei Butsurigaku, or simply Bussei—grew into a full-fledged academic discipline, one that would eventually overlap substantially with what is now called condensed matter physics.

Interestingly, the term Busseiron has often been treated as a uniquely Japanese label, with a somewhat unclear scope. Its meaning shifted over time and did not map neatly onto Western categories such as “solid-state physics” or “physical chemistry.” When analyzing the terms used for disciplines, historians of science have typically focused on the development of theories, research communities, and institutions, leaving the role of language largely unexamined. This makes Busseiron a particularly useful case for asking a more basic question: how does the field take shape and endure through the words scientists settle on to describe it?

A new study by Researcher Hiroto Kono of the National Museum of Nature and Science, with support from Professor Masashi Shirabe of the School of Environment and Society, Institute of Science Tokyo (Science Tokyo), Japan, takes up this question. Published in the journal Isis, this work examines how Busseiron evolved into the name of an academic discipline that stood the test of time. By tracing how the term was used, debated, and institutionalized, Kono reconstructed the historical process through which a major branch of Japanese physics developed. The study was made available online on April 07, 2026, and published in Volume 117, Number 2 of the journal on June 01, 2026.

First, Kono examined textbooks, journal articles, conference programs, and roundtable discussions from the 20th century. He tracked how Busseiron’s scope expanded over time, comparing this with the parallel development of solid-state and condensed matter physics in the West. This analysis showed that Busseiron did not simply grow out of the specific wartime research that first used the name. Instead, its meaning kept broadening, absorbing new topics ranging from ferroelectricity to electron emission to polymer chemistry, eventually including subjects that had originally been excluded from it.

One factor that held this loosely defined field together was a clear dichotomy against Soryûshiron, the Japanese term for the theory of elementary particle physics. Anything related to matter yet distinct from particle physics could be placed under the Busseiron label, which had become an umbrella term by the end of the 1940s. Notably, an attempt by some of the field’s own founders to replace the word with “chemical physics” failed, and the looser term persisted instead. “This study offers a new perspective by showing that the formation of academic disciplines can be understood not only through the development of theories and research communities, but also through the history of names and language,” Kono explains.

One of the main takeaways from this work is that even as research becomes increasingly international, the terminology scientists use can remain deeply shaped by local language and history. “As this Japanese case attests, etymological studies offer new possibilities for exploring the role of national contexts in the development of disciplines in an age when the globalization of science tends to be taken for granted,” concludes Kono.

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About Institute of Science Tokyo (Science Tokyo)
Institute of Science Tokyo (Science Tokyo) was established on October 1, 2024, following the merger between Tokyo Medical and Dental University (TMDU) and Tokyo Institute of Technology (Tokyo Tech), with the mission of “Advancing science and human wellbeing to create value for and with society.”

Journal

Isis

DOI

10.1086/740958

Method of Research

Content analysis

Subject of Research

Not applicable

Article Title

Coining a Discipline: The Formation and Perpetuation of a Japanese Branch of Physics of Matter

Monday, August 10, 2026

Marine microplastics carry chemicals of concern from plastic additives even after fragmentation

Plastics collected around Japan reveal that additive-derived chemicals can leach out, sorb onto microplastics from surrounding waters, or persist, highlighting the need to consider environmental behavior beyond product-based chemical controls.

National Institute for Environmental Studies

Sampling areas and collection locations for microplastics and larger plastic debris around Japan — image:
Blue labels indicate marine areas where floating microplastics were collected from surface waters. Red labels indicate locations or regions where larger plastic debris was recovered from riverine, coastal, and seafloor environments.
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Credit: National Institute for Environmental Studies, Japan

Background

Plastic pollution is not only a marine litter issue; it is also closely linked to resource circulation and chemical management. Plastic products contain a wide range of additives, including antioxidants, plasticizers, ultraviolet stabilizers, and flame retardants. Some of these chemicals are regulated or managed due to concerns about their effects on human health and ecosystems.

Once plastics enter the environment, exposure to sunlight and waves can cause degradation and fragmentation. Larger plastic debris may break down into microplastics, generally defined as plastic particles smaller than 5 millimeters. These smaller particles can disperse more widely in the marine environment. Fragmentation also increases the surface area of plastics relative to their mass, potentially affecting both the leaching of chemicals from plastics and the sorption of chemicals from surrounding water and particles.

Methods

A research team led by Go Suzuki of the National Institute for Environmental Studies, Japan, in collaboration with the Tokyo University of Marine Science and Technology and Nagasaki University, analyzed additive-derived chemicals in floating microplastics and larger plastic debris collected from coastal, offshore, riverine, and seafloor environments around Japan.

Floating microplastics were collected from five marine areas: Tokyo Bay, the Genkai Sea, Pacific coastal waters, waters off Hokkaido, and Japan Sea coastal waters. Larger plastic debris, including bags, ropes, nets, and hard fragments, was recovered from offshore and coastal areas across Japan, as well as from a river drainage pump station in Tokyo. The researchers identified the polymer types of the samples and analyzed extracted chemicals using gas chromatography–mass spectrometry.

Results and discussion

A wide range of chemicals were detected in both microplastics and larger plastic debris, including antioxidants, plasticizers, ultraviolet stabilizers, flame retardants, and polycyclic aromatic hydrocarbons. Based on detection frequency, concentration, and regulatory or management relevance, the researchers focused on three groups of chemicals: Irgafos 168-related compounds, di(2-ethylhexyl) phthalate (DEHP), and hexabromocyclododecane (HBCD).

Irgafos 168 is an antioxidant used to reduce oxidative degradation in plastics such as polyethylene and polypropylene. The distribution of Irgafos 168 and its oxidation products differed by polymer type and particle size. The observed patterns were consistent with leaching and transformation from within the plastic matrix.

DEHP is a plasticizer historically used primarily in flexible polyvinyl chloride products. It was widely detected in both microplastics and larger plastic debris. In some samples, concentrations exceeded 1,000 micrograms per gram (equivalent to 0.1% by weight). DEHP concentrations were higher in floating microplastics than in larger plastic debris recovered from the seafloor in both polyethylene and polypropylene samples. The results suggest that, in addition to chemicals remaining within plastics, DEHP present in surrounding water, suspended particles, and organic matter may be sorbed to microplastics from the surrounding environment.

HBCD is a brominated flame retardant that has been used in materials such as expanded polystyrene. Because it is persistent, bioaccumulative, and capable of long-range environmental transport, HBCD is regulated as a persistent organic pollutant. The researchers detected HBCD at concentrations of 110–590 micrograms per gram in microplastics collected from the Genkai Sea, Pacific coastal waters, and Japan Sea coastal waters. The findings indicate that fragmented plastic particles containing HBCD can remain mobile in the marine environment and may act as secondary sources of exposure.

The study shows that fragmentation does not necessarily remove chemical concerns associated with plastics that have entered the marine environment. Chemicals may leach from plastic matrices, may be sorbed to fragmented particles from the surrounding environment, or may remain in those particles during transport. Product-based chemical controls alone may not fully capture these processes after plastics enter the environment.

Future perspectives

Further research is needed to determine how much of the chemicals associated with microplastics are taken up by organisms and whether they contribute to ecological effects. It is also important to identify the sources and release pathways of plastics containing chemicals of concern and to apply this knowledge to leakage prevention, selective collection, and appropriate treatment.

These findings provide a scientific basis for connecting measures to address marine plastic pollution with chemical management. They may also contribute to discussions on the international legally binding instrument on plastic pollution currently under negotiation.

This article was selected for the Supplementary Cover Art for Environmental Science & Technology, Vol. 60, Issue 27. The cover image is available on the journal’s issue webpage.

(https://pubs.acs.org/toc/esthag/60/27 )

Additive-specific pathways in marine-leaked plastics

Conceptual illustration of the distinct environmental behavior of three substances highlighted in the study. Irgafos 168-related compounds are affected mainly by leaching and transformation from within the plastic matrices. DEHP may be sorbed to microplastics from the surrounding environment. HBCD can remain in fragmented particles during marine transport. The dots are schematic and do not quantitatively represent chemical concentrations or particle numbers.

Credit

National Institute for Environmental Studies, Japan