A Nagasaki survivor and physician recounts his life's work

Dr. Masao Tomonaga was 2 when Nagasaki was bombed. In August 2025, he spoke with Ira Flatow about a lifetime caring for fellow survivors.

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  Hey there, it's Ira Flatow, and you're listening to Science Friday. This week marks the anniversary of the US's bombing of Hiroshima and Nagasaki. So today, we're resharing this conversation from last year, memorializing the 80th anniversary. An estimated 210,000 people died instantly or within five months of the bombings. Another 210,000 survived and became known as Hibaksha in Japanese. For decades, Hibaksha have been receiving medical care at specialized hospitals designed to care for atom bomb survivors. And to this day, those hospitals are busy and filled with survivors who have suffered the medical consequences of the bombings.

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  Dr. Masao Tomonaga was a doctor at one of these hospitals. He was just two years old in Nagasaki when the US bombed the city. Years later, he became a physician and ultimately ran a Red Cross hospital in Nagasaki that cared for Hibaksha, just like himself. Now, he directs a nursing home for Hibaksha and still sees patients regularly. Dr. Tomonaga is my guest on Science Friday today. Welcome to the show.

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  Nice to meet you.

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  Thank you. You were only two years old when the US bombed Nagasaki. What was your first memory of the aftermath?

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  I have no memory of atomic bombing in Nagasaki, especially what happened in our house. Later, when I became age four or five, my mother explained what happened. My mother was preparing lunch in the first floor, and I was sleeping on the second floor. But suddenly, the blast came, and our Japanese wooden house, half-broken, not completely, half-broken.

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  So my mother came up to broken second floor and found me in a narrow space under the roof, and she took me out successfully. If she was not successful to take out me from the space, maybe I was burned by a firestorm, firestorm, after one hour or two hours. So I was a lucky boy. I was a lucky boy. There were many unlucky boys and girls, yeah.

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  Your father was a physician. He was a doctor. Was your father working as a doctor during the bombings?

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  No. My father actually stationed in Taiwan. He was serving Japanese Army Air Force as medic. My father first received information about Nagasaki disaster by bombing. He first thought his wife and the newborn son already dead. But one month later, a letter from my mother reached him. So he was so glad to read.

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  So he came back to Nagasaki. Did he take care of the survivors when he returned?

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  Yeah. He became one of the main doctors who take care of atomic bomb survivors, especially as a hematologist. It's a blood disease specialist. And later, my father found among children, acute leukemia case started to increase.

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  So the leukemia was due to the radiation?

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  Yeah. This was actually due to radiation because the distance from the ground zero, this distance shorter, the distance, the increased incidence of acute leukemia among citizens was increased. We call it dose-dependent dependency was clearly shown.

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  So your father was one of the first people to realize that the leukemia he was seeing was becoming more common in the survivors, correct?

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  Correct, correct. That was happening also in Hiroshima city simultaneously, as if there were two experiments of massive radiation on citizens.

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  So let's move a little bit ahead. Why did you decide to become a doctor?

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  My family was actually from my grand-grandfather, all doctors. So I was growing up surrounding doctors. So it was my natural will to become a doctor. And more than that, when I became a high school boy, I must prepare for examination to in medical school. My knowledge about atomic bomb-induced leukemia was increased.

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  So I have a fear I should be also becoming a leukemia patient. So I finally decided to go to medical school and to learn why leukemia was induced by radiation, atomic bomb radiation, yeah.

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  After you graduated medical school, why did you want to study and take care of other survivors? Why was that important to you?

• 6:48Speaker 02

  Yeah. When I become a doctor and I decided to enter hematology to study and treat leukemia patients as a Hibaksha care doctor, yeah. So this continued over entire my life. Because the diseases which developed from atomic bomb survivors continued even now, even now.

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  Are there still any cases, do you think, of illnesses from the radiation, whether it's leukemia or others, still being discovered left from the bomb?

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  Yeah. Actually, we first observed leukemia increase in the first 20 years, but leukemia began to decline gradually. We thought this was the end of radiation effect on human being, but it was not true. Around this 20 years phase, cancer, solid cancer such as lung cancer, colon cancer, and so on, began to increase among many survivors.

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  So it continues long, very long, until present time. And other than leukemia, we've discovered that in 1980s, almost 40 years after atomic bombing, another disease which is similar to leukemia but quite different disease of the elderly people, elderly leukemia, began to increase. That name is Myelodysplastic Syndrome. We abbreviation is MDS. This is the first discovery in Hiroshima and Nagasaki. This is continuing now.

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  So after 80 years, our radiation effect is continuing.

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  Is that surprising? Was that surprising to you?

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  Yes, surprising, surprising. So we decided to begin research on why such a long-time induction of malignant diseases by radiation actually happens. There must be some mechanism for this. We finally discovered that those radiation cause genetic abnormality in each cells of organs, and some of the such cells are called stem cell, very primitive, primitive cells, which every day produce red cells, white cells, and so on.

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  But still, these cells are not leukemia cells. This condition continues for more than 60 years, 70 years. Some of them began to develop actual MDS. And MDS is also a lethal disease because after four, five years of mild clinical course, many MDS patients develop acute leukemia and finally die. The treatment is very inactive. So we must say leukemia and other cancers related to radiation are lifelong effect

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  of atomic bombing.

• 10:40Speaker 01

  Wow. Those are the long-term effects.

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  Very long term, very long term.

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  Yeah, they certainly seem surprising. Who would have thought back 80 years later?

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  No one, no one. Actually, we didn't at all.

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  Yeah. But there were those short-term, immediate effects from the bomb itself, right? We had miscarriages, birth defects, not to mention the severe burns?

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  Yeah, severe burns was most popular injury given by atomic bomb heat race, heat race. Those who died of severe burn, the number was the greatest among early deaths of Hibaksha.

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  Coming up after the break, how the atomic bomb lives on.

• 11:41Speaker 03

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  What about the psychological effects?

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  Yeah. We doctors responsible for HIBACCA care began to see many HIBACCA's who are exposed to high dose radiation began to complain. Every year during the atomic bomb season—that starts about June, July, August—they often complain of sleeplessness, anxiety, and the flashback of atomic bomb experience. And their psychological condition deteriorates

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  remarkably. So we performed 8,000 large-scale psychological examinations by using WHO questionnaires, which is a powerful scoring methodology. 12 is the highest scores. So we found within 1.5 kilometers from the ground zero, almost all survivors showed very high score, over 10 to 12. So this was our surprise. That was done in 1995, 50-year anniversary

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  of atomic bombing. We performed this large-scale study.

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  What about now?

• 13:54Speaker 02

  Yeah. I began to feel that their memory is fading, fading out. In their 50s, 60s, their memory was very clear, and they always complained of their experience. But recently, when they got over 80 years, their memory seemed to be fading, fading, fading. So that is maybe a good point for them, too. They have been relieved from the anxiety and depressive states. They are now very spending calm days.

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  Yeah. And I know that you follow them, because I understand you run a nursing home for other survivors. Tell me about that. How many people there?

• 14:50Speaker 02

  450, 450 in total. And every day, I examine 20 to 30 patients who suffer from transient fever, diarrhea, and sometimes coronavirus infection, influenza, and so on. But among such daily diseases, we sometimes find MDS and cancer in cases of short-distance survivors.

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  I read that some patients describe it like the atom bomb is still in their bodies.

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  Yeah, that was an astonishing moment for me when I conveyed my diagnosis, actually, to chemi to patients. She was 76 years old at the time. She said, "I was confident that the atomic bomb is surviving in my body, deep body."

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  Tell me more. What did she mean by that?

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  She meant not radiation itself. Most HIBACCA's have no such residual radiation, except plutonium. About 20 years ago, one of our researchers at Nagasaki University found plutonium particles deposited in several organs of autopsied cases of atomic bomb survivors, most often lungs and bones. Those calculated from this deposited plutonium particles was

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  so small, very tiny amount. So it is impossible to suspect their after bombing deduction of cancer was maybe negligible, negligible.

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  Negligible. Do you have a message for those of us on this 80th anniversary of the bombing?

• 16:57Speaker 02

  Yes. 80 years is enough period. If we can understand the atomic bomb is inhumane weapon. When a large-scale nuclear war happens, the human being could be cessation. So why our society cannot abandon nuclear weapons? That is my largest problem. I'm working for

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  the realization of nuclear weapon-free world, and I want to talk to leaders of nuclear weapon states, and I urge their decision to make the nuclear weapon be abandoned. Yesterday, I met some youth at the United Nations, and I talked, and they clearly understood. But how these new generation will protest to their government, especially in nuclear weapon

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  states government, that is very unclear, unclear. Yeah. That is the biggest problem.

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  Dr. Tomonaga, I want to thank you for joining us today.

• 18:30Speaker 02

  You are very much welcome, yeah.

• 18:32Speaker 01

  Dr. Masao Tomonaga is a survivor of the atomic bombing of Nagasaki and director emeritus of the Japanese Red Cross Nagasaki Atomic Bomb Hospital. Special thanks to Laura Pelisser for her help with this interview. This episode was produced by Rasha Aridi. I'm Ira Flatow. Thanks for listening.