70 Years of Evidence

On the day the atomic bomb was dropped, uranium remained in the bodies of those who were not present at the site.

A research group from Nagasaki University reported in 2023 that they detected uranium, believed to be derived from the atomic bombing, in lung cancer tissues of hibakusha (people who entered the vicinity of the epicenter after the bomb was dropped). Notably, the presence of tiny radioactive particles known as “black death balls” was confirmed within the tissues. These particles, measuring only a few micrometers in diameter, have remained in the human body for over 70 years, invisible to the naked eye.

This research indicates that not only direct exposure to the blast but also internal exposure through residual radiation—commonly referred to as “black rain” and dust—has been etched into the human body at a material level. Hibakusha have long faced difficulties in having their suffering recognized within the framework of support for atomic bomb victims. Due to the reason that they “did not directly experience the blast or thermal rays,” a historical gap has emerged between the reality of the bombing and the system. The detection of uranium after 70 years appears to be a quiet rebuttal from matter against that “gap.”

Around the same time, eight students from Hiroshima City were preparing to be sent to the Review Conference of the Treaty on the Non-Proliferation of Nuclear Weapons (NPT). This initiative is part of the ongoing “Hiroshima Peace Grant” and youth dispatch project that Hiroshima City has continued since 2013, allowing the younger generation from the bombed area to stand at international conferences and convey the inhumanity of nuclear weapons in their own words.

The “memory of matter” detected by scientists and the “words of people” that the students are trying to weave together come from entirely different angles. However, both stand before the same question—how can the reality of the bombing be conveyed to the “next” generation?

What the “Death Balls” Reveal — The Gap Between System and Reality

Let’s delve a bit into the research.

A group led by Associate Professor Kazuko Nanjo at Nagasaki University confirmed the presence of uranium in lung cancer tissues of hibakusha using synchrotron microbeam fluorescence X-ray analysis. Additionally, the “black death balls” found within the tissues are high-concentration radioactive microparticles containing fission products and uranium, believed to have been generated during the explosion and dispersed into the atmosphere, subsequently inhaled into the body.

It is crucial to note that these hibakusha were not directly exposed to the epicenter but were “hibakusha who entered the city” after the bombing. It is estimated that there are about 270,000 such individuals, but because they did not receive direct exposure to initial radiation, evaluating the effects of radiation has been challenging, placing them at a disadvantage for the issuance of hibakusha health notebooks and disease recognition for many years. The recent Hiroshima High Court ruling in the “black rain” lawsuit, which recognized all plaintiffs as hibakusha, is still fresh in memory, yet it remains difficult to say that the recognition of the overall damage to hibakusha has progressed sufficiently.

The scientific fact of uranium detection has provided a piece of evidence against the gap between the system and reality. The claims of hibakusha that “my body hurts” and “I couldn’t stop coughing” have long been treated as subjective testimonies. Now, matter—particles that had remained silent in lung tissues for 70 years—has responded, saying, “I was here.” This structure prompts a moment of reflection.

What supports the testimonies is the matter left within the bodies of the witnesses themselves. The words spoken by people and the matter retained in their bodies represent two sides of the same reality. The “weight” of scientific evidence lies not only in the reliability of the data but also in the context of who proved what and over how much time.

What the Eight Students Will Bring to New York

The NPT Review Conference is held every five years at the United Nations headquarters in New York. It serves as a platform for nuclear-armed and non-nuclear-armed states to discuss the three pillars of nuclear disarmament, non-proliferation, and peaceful use of nuclear energy. In recent years, due to the impact of the Russia-Ukraine situation, reaching a consensus has become exceedingly difficult. The previous conference in 2022 did not result in the adoption of a final document due to opposition from Russia.

Amidst the harsh realities of international politics, eight students from Hiroshima are being sent out. They will convey the message from the bombed area through participation in side events and dialogues with representatives from various countries. In preparation for their dispatch, the students underwent pre-training, listened directly to hibakusha, and studied the history and present of Hiroshima before traveling.

One of the dispatched students expressed, “When a hibakusha said to me, ‘You will carry on our legacy,’ I realized for the first time what I was about to bear.”

Within this statement lies something that the speaker has yet to fully articulate. The expression “continuation”—it is not merely a passing of the baton but a sense of standing on the extension of an unfinished event. For hibakusha, the bombing is not a “past event” but something that continues to reside within their bodies. The research indicating uranium detection provides material backing for that very fact.

The words the students will speak at the international conference may not directly influence diplomatic negotiations. However, the very fact that “young people from the bombed area are speaking in their own words” adds a certain temperature to the atmosphere of the conference. In a place where discussions on nuclear disarmament often become confined to numbers and legal texts, ensuring a circuit for human voices holds intrinsic significance.

Two Circuits Operating Simultaneously

Looking back, these two events were reported around the same time by coincidence, and there is no direct connection between them. The research team from Nagasaki University and the student dispatch project from Hiroshima City are operating in separate contexts.

However, when viewed from a slight distance, a single structure becomes visible.

There are two circuits simultaneously operating to convey the memory of the bombing to the “next” generation. One is the circuit of matter—science reads the traces left in the human body and records them as data. The other is the circuit of words—young generations listen to the experiences of hibakusha, transform them into their own words, and deliver them to the international community.

The circuit of matter remains unchanged over time. Uranium was still present in the lungs 70 years later. However, without the technology to “read” it and the will to “attempt to read” it, matter remains silent. Conversely, the circuit of words must inevitably change over time. As hibakusha age, the number of those who can provide direct testimony decreases each year. According to Hiroshima City, the average age of those holding hibakusha health notebooks has surpassed 85. As the “primary information” of testimonies is lost, what the students undertake is a task akin to translation—rearticulating the words they have heard through their own bodies.

These two circuits are interdependent. Scientific evidence alone does not move people. The data may be accurate, but it cannot answer the question of “why this is a problem” by itself. On the other hand, words alone cannot withstand doubts about “whether it really was like that” over time. Matter supports words, and words give meaning to matter. This complementary relationship forms the quiet yet solid framework of the endeavor to inherit the memory of the bombing.

Points to Watch Going Forward

I would like to highlight a few specific points.

First, how the detection of uranium in hibakusha will be reflected in the administrative support for hibakusha. There is a significant distance between the academic evaluation of research results and their connection to a review of the system. Even after the ruling in the “black rain” lawsuit, the criteria for recognizing hibakusha remain under discussion. It is necessary to carefully follow the process through which scientific knowledge is translated into policy.

Second, the outcome of the NPT Review Conference. Even after the entry into force of the Treaty on the Prohibition of Nuclear Weapons (TPNW), the divide with nuclear-armed states remains unbridged. Whether the dispatch of students will continue to function as a sustainable mechanism rather than ending as a “one-time event” is crucial. Hiroshima City’s dispatch project has over a decade of accumulation, but challenges remain in terms of budget scale and follow-up systems for participants regarding sustainability.

Third, the connection between research and education. How the research results of uranium detection will reach the field of peace education is important. If students can approach international conferences not only with the testimonies of hibakusha but also with the latest scientific knowledge, the two circuits of “evidence” and “words” will intersect within a single individual.

As we approach the 80th anniversary of the bombing, the inheritance of memory expands not only to the question of “who speaks” but also to “what speaks.” Even if the day comes when human words can no longer reach, matter will still be there. And what cannot be spoken by matter will be articulated by people.

I want to take a moment to carefully observe this time when both are operating simultaneously.