50th anniversary of the A-bomb attacks – the ongoing research into the effects of radiation

Survivors of the A-bombs in Hiroshima and Nagasaki
Survivors of the Hiroshima and Nagasaki atomic bombs (© Creative Commons)

In 1945, the United States dropped atomic bombs on Hiroshima, killing 75,000 people instantly. Tens of thousands more died in the following years as a result of the effects of radiation. A few days after the first bomb, a second one was dropped on Nagasaki with similarly disastrous consequences. Doctors and scientists are still studying the effects of the world’s first atomic bombings.

Original broadcast: July 31, 1995


Radio Netherlands, the Dutch international service, presents a “Research File” special. The programme is produced and presented by Eric Beauchemin.

50 years ago on August 6th 1945 at 8:15 in the morning, a bright light pierced the sky over Hiroshima, Japan. Seconds later, darkness enveloped the city. A blazing wind scorched Hiroshima and its inhabitants. 75,000 people were killed instantly. Another 125,000 are believed to have died since then. 50 years later, the survivors continue to remember, and doctors and scientists are still studying the effects of the world’s first atomic bomb.

50 years after the United States dropped atomic bombs on Hiroshima and Nagasaki, groups of school children from all over Japan continue to pay their respects. They gather at the Children’s Memorial in Hiroshima, bow their heads and sometimes sing songs in memory of the thousands of children who were killed. For these kids and the rest of Japanese society, the memory of the atomic bombs remains very much alive. It’s been kept alive over the past half a century in part because of ongoing research into the effects of the first and only atomic bombs ever used against civilian populations. Much of the research has been conducted by the Radiation Effects Research Foundation in Hiroshima. Dr. Mortimer Mendelsohn is the foundation’s vice chairman.

The A-bomb in Hiroshima was a one of a kind device. It was a cannon where one piece of uranium got shot into another. When it explodes and the two pieces of uranium approach each other, they become a critical mass and you get an atomic fission reaction. This produces an enormous amount of energy and with it, an enormous amount of heat, which very rapidly blows the device apart. So for about a microsecond, it is as if there was suddenly a sun created at about 580 metres in the sky. Anyone out exposed to that sun, their skin exposed to the sun, got a severe sunburn. The blast then produced a huge wave, which then swept out, knocking buildings down for several thousand metres. And then the radiation, which would not have been felt, would have caused various types of internal damage which would show up as radiation effects about a month later.

On August 9th, 1945, three days after the HiroshimA-bomb, another atomic device was dropped, this time on Nagasaki in southern Japan. 40,000 people were killed, 80,000 injured. In the days after the bombs exploded, rescue efforts were complicated by the fires which broke out in both cities. The infernos destroyed many of the buildings and houses in Hiroshima and Nagasaki, which had not been pulverised by the blasts. In both cities, almost every single building near the hypocentre – the point above which the bomb exploded – was destroyed. Temporary first aid clinics were set up, but many o the doctors and nurses had also been killed. According to Dr. Kiyoshi Kuramoto of the Red Cross Hospital in Hiroshima, the remaining staff was overwhelmed by the enormity of the devastation.

We had ordered the Nagasaki University Hospital for the rescue. We went to the university hospital. No doctors, no nurses at that time, only a few teams of military rescue. But we did not have enough medicines at that time. And still was looking for some medicines for the victims in hospital drug stores, and we found some injection material and so on and so forth in the underground of the university hospital, and we picked up some medicine but quite few. Because infusion liquid was so hot, high temperature, we couldn’t touch them. Only we treated these victims burning.

The burns were severe and often covered much of the survivors’ bodies. Many people were so badly burned that the skin on their hands literally dripped off their fingernails. In other cases, the survivors’ skin had been burnt off and all that remained was flesh. And in the days and weeks that followed, says Dr. Mendelsohn, the survivors began to develop keloids.   

Well, a keloid is a response to injury where there’s a build-up of scar material on it. It’s a characteristic of different racial types to do that. The Japanese have it. Some African peoples have it. A scratch can end up being a significantly raised scar a few weeks, months after the episode. The Japanese A-bomb survivors certainly had it. The keliods it turns out have since regressed. So they don’t last forever. They gradually shrink, and you don’t see much evidence of it now.

In the first years after the bombs, many of the victims were operated on to remove the keloids. But in 80% of the cases, they reappeared. In many cases, it took 10 to 20 years for the keloids to disappear completely. Doctors are still trying to determine whether there’s a link between keloids and a greater risk of developing skin cancer.

For one week, Dr. Kiyoshi Kuramoto helped treat the survivors at Nagasaki University Hospital.

We couldn’t understand what was happened there, what was happened in human body. We couldn’t understand. Only we can see was burning, injuries, trauma and so forth. Only we could see was haemorrhage, such as diarrhoea, bloody diarrhoea, nose bleeds and so forth They complained of thirst and wished to have water but we couldn’t give them water at that time. No time to give them water. Only we treated the severe wounded, injuries to prevent the infections. Girls and boys, they were down on the ground. There’s no injuries, no burns at that time. It was funny for me. So these children wanted to have water and complained, sore throat. The next day, I went there, same place these children had died. No injuries, no burns. So I couldn’t get the diagnosis.

It wasn’t until the 15th of August when Japan surrendered to the Allied Forces that the Japanese were actually informed that atomic devices had been used on Hiroshima and Nagasaki. It took many months and even years before doctors and scientists began to understand the effects of such high levels of radiation on human beings. The radiation, says Dr. Mortimer Mendelsohn, primarily affected the victims’ bone marrow.

The bone marrow cells of the body are damaged by the radiation, and you run out of white blood cells and palates, which means that you are susceptible to infection, and you start showing inability to clot your blood, and so the slightest bruises produce big black and blue marks. If this situation is severe enough, the people will die from these effects. If the bone marrow recovers in time, the people survive and they go on to express various kinds of delayed effects which is what this foundation was set up to study.

The foundation was established in 1947 under another name: the Atomic Bomb Casualty Commission. It was run by the US National Academy of Sciences, with funding from the US Atomic Energy Commission. A year later, the Japanese National Institute of Health joined the research programme to study the medical effects of the atomic bombs. By 1949, when Dr. Kuramoto was employed by the Red Cross Hospital in Hiroshima, the medium-term effects of nuclear radiation were becoming abundantly clear.

We saw many outpatients here day by day by day, day after day. These patients, outpatients, 100% exposed at that time. We saw up to 200 or 300 patients every day at the outpatient clinic. We also have 200 or 300 more inpatient too. And then we found the occurrence of second radiation symptoms, such as malignant disease, cancer, and leukaemia were occurred day by day. We saw patients every day as leukaemia patients with high fevers. We tried every kind of treatment for leukaemia as we know, but at that time the prognosis of leukaemia was so bad.

The A-bomb survivors ran a risk 10 to 20 times greater than the normal population of developing leukaemia. Within a few years, most of the leukaemia patients were dead. It wasn’t until a few years later, says Dr. Mendelsohn, that the second major effect of radiation became apparent: cancer.

The cancer effect, the solid cancer effect took about 10 years before anyone realised it was happening, and it has been steadily increasing ever since. It’s now a very well understood thing. It seems to be happening in all of the tissues of the body, so all kinds of cancer are increasing at approximately the same rate, as best we can understand it.

The closer the survivors were to the hypocentre, the greater their risk of developing cancer and other diseases. Some cancers, like thyroid cancer, began to appear a decade after the blast. While others, like gastric cancer, colon cancer and multiple myelomas or bone marrow tumours did not begin to appear until 1975, 30 years later. Scientists today continue to closely monitor the A-bomb population to discover the exact effects of radiation on the human body. Children and infants were particularly susceptible to the enormous amount of radiation released by the bombs, but the radiation took its heaviest toll on the unborn.

Birth defects in the classical sense of monsters or no heads or common things like split palate, there was no evidence of them increasing. There is evidence of damage, in utero damage. Most of it is a whole new set of syndromes involving the evolving brain. It first became obvious as in smaller head size in the kids that were irradiated in utero, particularly in the second half of the first trimester. Later on it was correlated with personality changes, seizures at the high doses and then most recently it’s been tied to intelligence testing. You can get a clear dose response to the change in IQ. It’s very impressive to see how the machinery of constructing a brain can be distorted by head radiation at the right time in pregnancy. It’s a very disturbing effect. The Japanese have a high sensitivity toward anything involving mental disease or birth defects, and they are very sensitive about these children, what were children, and have been protected strenuously by a variety of organisations throughout Japan.

The survivors both young and old faced a greater risk of getting a wide variety of diseases. But many of them also suffered from health problems which were more difficult to define. According to Dr. Namumasa Kimura, a physician in Hiroshima, one of these complaints was dubbed “atomic bomb fatigue disease”.

Up to 10 years after the atomic bomb was dropped, the victims suffered from fatigue. They were apathetic, inactive and nervous. They had difficulty in leading a social life. They always felt tired. But doctors could find nothing wrong with the victims’ blood. So for a long time it was believed that the survivors were inventing this. But research carried out by a professor at Hiroshima University Hospital showed that 1 out of 3 survivors suffered from fatigue. They had difficulty concentrating and adapting. They suffered from a greater risk of developing amnesia, headaches, vertigo and emotional instability.

While intense efforts were made to study the physical effects of nuclear radiation, little or no attention was paid initially to the psychological effects. Most if not all the survivors, according to Dr. Ishikawa Hiroyoshi, a psychologist at Seijo University in Tokyo, were severely traumatised by the experience.

Well, one of the key words for the understanding of this experience is aimlessness. For some older generation, they cannot find out aim to live, what to think, what to feel. So they are in a situation of something like depression. EB: Is this something they have suffered from since the bomb exploded or is it something that’s come about recently? Since the explosion of bomb. So this feeling has a long, long history. In some cases, people are getting better and better, but some people are still in this situation of depression.

Dr. Mendelsohn admits, in retrospect, that the studies carried out by the Atomic Bomb Casualty Commission, the ABCC, and its successor the RERF, the Radio Effects Research Foundation, should also have examined the trauma caused by the bombs.

It’s a very clear shortcoming of the ABCC/RERF studies. Why, I suspect is complex. In part it’s because people grabbed the things that were easiest to do first, and so even the Americans who were here would not be thinking that so much as they would cancer and whatever. Another reason is that the Japanese approach to life really doesn’t include much in the way of psychiatry or concern about traumatic effects on behaviour and that kind of thing. They block that kind of invasion of the person. They don’t like to talk about it. They certainly don’t want to be studied about it. My guess is that in the end there was a lot of deference to that social attitude.

The recovery of the survivors was hampered not only by their horrific experiences, but also by the policies of the American occupation forces to keep all matters related the atomic bombs. Until 1951, when Japan and the United States signed a peace treaty in San Francisco, the Land of the Rising Sun was occupied by the United States. Physicians like Dr. Dr. Kiyoshi Kuramoto of the Red Cross Hospital in Hiroshima had access to data on the effects of the bombs, but he says the occupiers imposed strict rules to prevent the publication of any information regarding the atomic bombs.

All paper reports had to be checked by authority. So we could not open the data at that time.  Nobody knows about it. These kinds of effects of the atomic bomb was very, very important information of military purpose.

It was clearly the policy of the occupation to downplay the A-bomb effects. There are those who claim that it was because what was happening was classified. I don’t think that’s true. The only thing classified about Hiroshima and Nagasaki were the details about the weapons themselves. I think the reason they were doing it was part of the occupation psychology or sociology, the desire to keep things calm to avoid any type of public arousal or strong attitude about anything that was going on. I’d like to think that this was a benevolent frame of reference, that they were really trying to rebuild Japan as quickly and strongly as possible. So I don’t look at this as a negative or evil thing, but there’s no question that public information, movies, photography, details about day to day stuff, all of this was discouraged strongly by the occupation forces.

Because of this policy, growing numbers of Japanese began to believe that the United States was intentionally withholding information. In fact, during the initial period of the occupation, US military officials are reported to have actively tried to prevent the survivors from speaking about what had happened. According to Dr. Mendelsohn, the survivors, who are known as hibakusha in Japan, were also shunned by the rest of society.

The hibakusha early on were marked people, both in their own minds and the minds of the people around them. They were probably prejudiced against in terms of whether they should be employed, certainly in terms of whether you should allow your children to marry them. There was a lot of concern about what the offspring of the hibakusha would be like. All of these fears to my mind seem to have pretty much run their course. The hibakusha are obviously surviving and I think that’s pretty well died down. Also the Japanese government has institutionalised a whole set of things that are directed toward dealing with being an A-bomb survivor, and there are  a whole array of medical benefits that these people get, which are quite substantial.

The Japanese government provides 80% of the survivors with a monthly check worth about $400. Those who were close to the hypocentre – the point of impact – and have had more serious health problems throughout their lives are entitled to up to $1400 a month.

It wasn’t until 1953 that the Japanese established their own organisation to study the effects of atomic radiation and provide medical attention to the A-bomb survivors. The Atomic Bomb Casualty Council decided to take a very different approach than the ABCC and its successor, the RERF. The RERF bases its research primarily on death certificates and medical check-ups conducted every two years. The Atomic Bomb Casualty Council, however, has focused on early detection of cancers and other disease which might be linked to the bomb. It provides medical check-ups twice a year to the survivors, and they can go in up to four times a year if they want. All this data as well as information provided by the RERF is stored in special air conditioned facility in Hiroshima. The research and treatment have been largely financed by the Japanese government, which provides comprehensive medical treatment to the survivors. Each survivor, says Dr. Shikako Ito, the Council’s deputy director, has been given a booklet to certify that they are indeed A-bomb survivors.

This is a handbook of certification of A-bomb survivors. In all Japan now, 330,000 A-bomb survivors living in all Japan. All of them have a special handbook, and this is the certification number. This is very important, and name and date of birth and sex and age at the time of bombing and present address. Next page shows exposure status.

The exposure status or dosimetry as its officially known is crucial in determining how seriously the survivors were affected by the atomic radiation. The closer the survivors were to the hypocentre, the more likely they were to suffer from after effects, according to Dr. Mortimer Mendelsohn of the RERF.

You’ve got this point source of radiation that did its thing in a matter of microseconds and then wafted up into the stratosphere, disappear. It emanates like a sphere in all directions, and that means you can relate the dose to an individual rather simply by estimating how far  that individual is from this point source and by estimating as best you can what kind of filtering material might be between the person and the bomb: so structural material from a house or from a factory or sitting behind a hill. These all affect dose to some degree. Our dosimetry system 86, the new dosimetry system, does all this, calculates all this if you give it the location of where the person was, whether he was in a house, whether it was a Japanese house, what position he was in, posture, male, female adult, child. From all of this, the computer system can construct the overall dose and the dose to each individual organ and the actual fluxes of particles that went through each part of the body.

Despite the RERF’s policy of openness, the foundation still refuses to release the dosimetry figures for individuals, citing the patient’s privacy. This continues to generate suspicion and even outright anger on the part of local organisations, like the Atomic Bomb Casualty Council. Some accuse the United States of having used the inhabitants of Hiroshima and Nagasaki as guinea pigs to discover the effects of nuclear radiation. They cite several reasons, including the fact that the bombs exploded about 600 metres above the ground, which ensured what Dr. Mendelsohn describes as a “clean episode”.

When A-bomb bursts in the air like these two did, you get this instantaneous blast and radiation and then the enormous heat that it generates quickly gets it to get swept up into the stratosphere. So there’s no radioactive fallout necessarily, no contamination on the ground. It’s just the pure airborne A-bomb effect. If it’s on the ground, it’ll spew dirt all over the place. Radioactive contamination will complicate this scene for a long, long time and complicate get either getting in to observe what happened or to treat or fix or do anything. Also the dosimetry is much more complicated on the ground. So that’s probably why they did it.

Half a century after the bombs, the research on the consequences of radiation on human beings continues. The 300,000 survivors in Japan as well as North America, Latin America and Korea continue to receive regular medical check-ups from the RERF and the Atomic Bomb Casualty Council. However, as the survivors age, it’s becoming increasingly difficult for researchers to establish whether the diseases the survivors are suffering from, like cancer and cardiovascular diseases, are directly linked to the bomb or are simply the result of old age. Scientists are also trying to see whether the survivors have passed on any diseases or genetic defects to the second generation, the children of the A-bomb survivors.

All biological systems are sensitive to heritable changes from ionising radiation. And there is every reason to think the human is too. The reason we haven’t detected anything, I think, is because the effects are not large and they are very difficult to measure. We anticipate with another 10 years of improvement in the kind of research that’s involved in genomics that we will be able to use the DNA of a family, compare the parents’ and the child’s DNA, and measure the heritable, mutational effect. But my prediction is it’s going to be somewhat like the mouse which is the nearest animal about which we have such information and that it will be of scientific interest to pin this down and to understand the risks involved but that it will not be of much social interest because it is going to be rare. It’s going to be a very rare event. Our calculations are that if the human is like the mouse, then the Hiroshima experience, for example, is just not big enough clinically to see a heritable, mutational effect.

Nonetheless, the second generation has been affected by the bomb. Like the children of survivors of the Holocaust in Europe or the Japanese internment camps in the former Dutch East Indies or other countries in Asia, the children of the A-bomb survivors are having to deal with the psychological consequences of their parents’ experiences. In recent years in the Netherlands, for example, growing numbers of children of survivors of the Holocaust or of the internment camps have been receiving counselling. The same holds true in Japan, says Dr. Hiroyoshi.

They are also suffering from very deep trauma because they have the side effect of going through their parents. So in a sense, their situation is much more difficult to cure because at the time of bombing, the explosion of bombing, some of them are in mother’s womb. This is, I think, much more difficult situation for recovering because they know nothing about the cause of this trauma. And also they have no relationships between the ??. They can only understand by reading books or speaking to some teachers or watching television. So those kinds of indirect relationships is one of the key factors for the understanding of the trauma of these young people.

The second generation is likely to keep the memories of the bomb alive in Japan for some time to come. But for the moment it’s the elderly first generation survivors who continue to remind Japan and the world of the suffering inflicted 50 years ago.

In Nagasaki Peace Park, a small group of old people still regularly stages a march to call for the elimination of nuclear weapons. The survivors also want to keep up pressure on the government to continue research into the effects of radiation. This research, says Dr. Mendelsohn, is probably the only good thing that came out of the horror 50 years ago.

I think the first and overwhelming lesson is that an atomic bomb is a horrendous weapon. Take Hiroshima for example: a normal city, if you will, at the end of a very difficult war, distorted city, but nevertheless a normal city. People going about their normal affairs, a nice summer morning, and then a fraction of an instant later, utter destruction over a radius of several miles. Enormous numbers of people killed and all the social structures destroyed. It’s a horrendous weapon. One would hope that mankind would learn to control it and never have to use it again. Focusing in on a completely different order of magnitude now, what we’ve learned from the bomb, I think it’s important to realise that all of the world’s radiation standards, and I mean all the international standards, all the individual, national standards are based on the radiation biology, human radiation biology that we’ve learned in Hiroshima and Nagasaki. This is a kind of small bit of benevolence that’s grown out of a horrendous experience. But it should be recognised for what it is. It’s a very positive contribution, and it’s come from the careful study of the A-bomb survivors.

This Research File special was produced and presented by Eric Beauchemin. Technical production: Werner van Peppen. This has been a Radio Netherlands’ presentation.