The atomic bombings on Japan in 1945 represent the only hostile use of nuclear weapons to date. The tribunal was therefore particularly interested in establishing the short-term and long-lasting effects of the Hiroshima and Nagasaki attacks even though the explosive yields of the two bombs (12.5 and 22 kilotons respectively) were substantially smaller than most present-day weapons with typical yields in the range of several hundred kilotons up to several megatons. The Japanese attacks were therefore equivalent to the use of only two small tactical nuclear warheads in modern terms which is conceivably the minimum level of use contemplated by modern field commanders in central Europe.
Evidence on the Japanese attacks was presented by Professor Iwasa (a survivor from Hiroshima) and by Dr. Saito a Japanese physician and authority on the physical injuries caused by the Hiroshima bomb.
Professor Iwasa who was the first witness to address the Tribunal recalled the grim scenes in Hiroshima on 6th August 1945. He read extracts from his report ( What Hibakusha Want ) to the Tribunal:
"I was in my garden about 1.2 kilometres from the point in Hiroshima where the bomb was dropped. At the moment of the explosion I felt as if I had been struck on the back of my head, and was knocked to the ground. I managed to rise a few seconds after that dreadful blast, and saw that all the houses and other buildings of Hiroshima had vanished from before my eyes, and only bits of broken tiles and rubbish were left there. Great fires were sweeping everywhere.
My mother was trapped under the house, but even using all my strength (I was a sixteen-year-old boy at the time) I was unable to rescue her. I managed to get to the swimming pool of the nearby middle school, haunted by the voice of my mother chanting 'Hannya-Shin-Kyo' (a Buddhist scripture) in my ears. I prayed, 'Mum, please try to escape', but I could only watch the house burning, tears in my eyes.
What I saw were the terrible scenes of an earthly hell. A four-year-old girl in the next house was nearly dead, her neck split open, her bronchial tube sticking out. All around where our house had been were people injured by the blast, heat and radiation that swept all over us at once; people burnt all over their bodies by the intense heat had their skin hanging down like strips of rag, their bodies full of pieces of glass.
I saw some of the people covered with flames falling on the road after barely crawling out of the collapsed houses.
Everywhere near the blast centre where I went the next day, the burnt remains of people packed together in the water, some in a small tub where they had tried to escape the fire."
Professor Iwasa also pointed out that even those who escaped sudden death from the nuclear explosion and those who came into the city looking for family members after the attack also became victims.
Dr. Saito's evidence provided the Tribunal with more quantitative information on the Hiroshima attack. His written submission established that a total of 140,000 people had died in Hiroshima by the end of 1945. The total mortality rate standing at 56.5% of the population within 2km of ground-zero at that time. Dr. Saito's report detailed the immediate physical injury caused by the explosion:
"The first cause of death of these victims was atomic burns, called flash burns, plus external wounds caused by blast. The epidermis of A-bomb victims a short distance from the hypocentre was carbonized, and their internal organs vaporized instantly. Those who suffered serious burns within 1.0km where there was no shelter from radiation died within one week at a ratio of 90-100 per cent. Deaths from acute symptoms from the A-bombing occurred till around the end of 1945. But 90 per cent of the victims who suffered acute symptoms were dead within two weeks, and almost all the others died 8 weeks after the bombing. Another effect leading to death was the destruction of haematopoietic organs by radiation. The decrease of white blood corpuscles caused the following symptoms: nausea, vomiting, loss of energy and vitality, diarrhoea, and loss of hair. Victims within 5OOm from the hypocentre died on the day after medical examination or after the next day, because their white blood cells had decreased to 150-400 per cubic millimetre. Autopsies undertaken within 2 weeks after the bombing showed the disappearance of lymphocytes from the lymph nodes, and of haematopoietic cells from the bone marrow as common characteristics. It also showed bleeding of internal organs. The examination of people who entered the city soon after the bombing showed abnormality of white blood corpuscles."
Dr. Saito's evidence also examined the medium and long-term after-effects of atomic bomb injury. Within several months, many victims who had suffered thermal injury at a range of 2-3km developed grossly swollen scar tissue known as keloids. This effect is virtually unique amongst atomic bomb victims and occurred with a very high rate of incidence among the survivors. Surveys in 1946 and 1947 also revealed impaired sperm production and abnormal menstruation amongst victims. By 1948 cases of eye cataracts and leukaemia had been discovered in the victims. During the period 1950-55 the leukaemia rate peaked at 94.85 cases per 100,000 of the population amongst those who had been exposed to radiation doses in excess of 100 rads. The equivalent rate for non-victims stood at 1.04 cases per 100,000. Dr. Saito also referred to recent reports indicating that many Hibakusha (A-bomb survivors) are now suffering from cancers of the stomach, breasts and lungs at increased incidences compared to non—victims. Both Japanese witnesses agreed that the effects of the atomic bombings are still being felt today by many victims.
Besides the direct testimony of the two Japanese witnesses, the Tribunal received a further submission from the Japanese delegation giving more details on the physical and medical aspects of the attacks on Hiroshima and Nagasaki. In addition the attention of the Tribunal has been drawn to an eyewitness account of the atomic bomb attack on Nagasaki and to a major compilation of scientific evidence on damage caused by the atomic bombs in the two Japanese cities8.
In weighing up the evidence from the Japanese experience the members of the Tribunal noted that many victims appear to have suffered from the complex synergistic effects of multiple sources of physical injury including flash burns, radiation and blast trauma. Although the total number of deaths attributable to the two atomic bombings is known fairly accurately up to the end of 1945 (140,000 plus or minus 10,000 dead in Hiroshima, 70,000 plus or minus 10,000 dead in Nagasaki) the total mortality rate since that time has been more difficult to establish as A-bomb effects cannot in all circumstances be isolated from other causes. Nevertheless the total number of attributable deaths by 1950 has been estimated at 340,000 for the two cities. It is certain that many hundreds if not thousands of people have died since that time through direct or indirect effects of the bombings (including, for example, the effects of psychological disturbances)
Although the Japanese evidence was invaluable to the Tribunal, it was noted that the casualty rates etc. cannot be directly extrapolated to possible present-day nuclear conflict scenarios on account of the special circumstances prevailing at the time, namely:
8 Hiroshima and Nagasaki - The Physical, Medical and Social Effects of the Atomic Bombings, E. Ishikawa and D.L. Swain (translators), Hutchison, London 1981.