The effects of nuclear weapons on human health

According to the Hippocratic oath, every physician pledges to serve his/her neighbour and save what life could be saved. For physicians and medical workers all over the world, the struggle for a world free from nuclear weapons is natural and logical. What could possibly be more contrary to a the ambition of serving mankind and saving lives than a weapon that within moments can annihilate our planet and every living thing? The World Health Organisation (WHO) wrote in a 1983 report that: “…nuclear weapons constitute the greatest immediate threat to the health and survival of mankind” (1)

1000 times more powerfulA nuclear explosion can cause damage to human beings in a number of ways – immediately and in the longer term. Nuclear weapons harm both living humans and foetuses in their mothers’ wombs. A nuclear explosion targeted on a city will damage hospitals and kill and injures medical staff, making it difficult to provide help for survivors. In Hiroshima, 140,000 people were killed by the atomic bomb. The total number of inhabitants of Hiroshima at the time is estimated at 350 000, which means about 40 percent of the inhabitants were killed as a result of the atomic bomb. In Nagasaki, the American atomic bomb killed more than 70 000 and injured many more.

When looking at health consequences of nuclear weapons use, it is important to keep in mind that the bomb Little Boy that was detonated in Hiroshima had an explosive power equaling 15 kiloton TNT. Fat Man, detonated in Nagasaki, had an explosive power of about 21 kiloton. Nuclear weapons in modern arsenals are much more powerful – e.g. one of the British Trident nuclear submarines has a total firepower of 24 megaton TNT! This means, some of today’s more than 20 000 nuclear weapons have a fire power more than 1000 times stronger than the bombs over Hiroshima and Nagasaki. A thought worth keeping in mind when discussing the threat posed by nuclear weapons on the health and survival of mankind.

A nuclear explosion creates an enormous shock/blast wave that reaches the speed of many hundreds of kilometres per hour. The blast kills people close to ground zero, and causes internal injuries such as lung injuries, ear damage and internal bleeding. The blast wave tears apart buildings and infrastructure far away from ground zero. Glass, bricks, concrete and wooden parts from destroyed buildings are hurled up in the air by the blast, threatening to kill or injure more people.

The explosion also causes thermal radiation at a temperature so intense that practically everything is vaporised. Severe burns and eye injuries are also consequences of the thermal pulse. The heat wave will ignite fires that may combine together and become immense firestorms, spreading out from the site of explosion. Within these areas, even people in underground shelters will die because of heat, lack of oxygen or from carbon monoxide or -dioxide poisoning.

The contour of a victim of the atomic bombing of Hiroshima

The contour of a victim of the atomic bombing of Hiroshima

One of the things that set nuclear weapons apart from conventional arms is that the former kills and wounds through radiation. This damage is caused by gamma and neutron radiation in both initial radiation as well as beta and alpha radiation in the radioactive fallout. The cells of the body suffer the damage caused by radiation. If exposed to a deadly dose of radiation, death caused by radiation sickness can occur quickly or within a few months. The system for blood production and infection defense in the bone marrow are very sensitive to radiation.

When a somatic (body) cell is irradiated, the energy carried by the radiation is transferred to the cell. There is a risk that the DNA molecule contained in the cell is damaged, either directly by the radiation or by so-called free radicals, molecules that are harmful to DNA, that are formed in the cell. Unless the DNA molecule can be repaired, the cell may either die or become a mutant or cancer cell. Leukaemia (blood cancer) develops within a few years, while cancer tumours in internal organs may show after a longer period of time, even many decades later. Pregnant women exposed to high doses of radiation suffer the risk of deformation of their children. There is also concern that radiation harms the gene pool, thereby affecting future generations.

Long after a nuclear explosion, radioactivity will be dispersed in the area close to ground zero and, depending on weather and winds, further away. This is called radioactive fallout. Humans are affected directly if the skin gets in contact with the fine particles. Radioactive particles can also harm indirectly, e.g. when people drink milk from cows that have grazed on contaminated grass, or through meat or vegetables that have absorbed radioactive substances from the fallout.


The cancer risk after a nuclear explosion

The risk for developing cancer increases among the survivors of a nuclear explosion and among those exposed to radiation. The long-term effects of radiation include a number of diseases, both cancer (e.g. breast-, thyroid- and lung-cancer) and leukemia (blood cancer). The risk for developing leukaemia increases if exposed to radiation at a young age – with by far the highest risks occurring among women exposed as young children.

The cancer risk after a nuclear explosionThe effects of the atomic bombings of Hiroshima and Nagasaki can still be seen. They have led to a significant increase in cancer rates among survivors, which can be seen if comparing cancer rates with other similar areas – an increase that can only be explained by the effects of the nuclear explosion. As a result of the long time it takes for cancer to develop after the exposure to radiation, the number of cancer victims has not yet reached its peak.

The US, Russia, the UK, France and China have signed the Comprehensive Test Ban Treaty (1996) and pledged not to test nuclear weapons pending the entry into force of the treaty. Thus, large scale nuclear testing has ended, but the health effects from more than 2000 nuclear tests conducted is an ongoing plague. Estimates from the 1990’s show that radioactive fallout from atmospheric nuclear testing will lead to more than 2 million cases of cancer globally. Other health effects are not included. (2)


Reproductive health

Reproductive healthIn areas close to nuclear test sites as well as after the bombings of Hiroshima and Nagasaki, an increase in foetal damage has been seen. Since rapidly changing cellular tissue is especially sensitive to radiation, the foetus is particularly vulnerable. Exposure of foetuses to radiation has been shown to increase the risk of childhood cancer. In addition, children exposed as foetuses to the Hiroshima and Nagasaki bombs had a significantly increased rate of microcephaly and intellectual disability. (3)

Extensive research with animals has proved that radioactive radiation causes hereditary malformations. Yet, is not been confirmed that the same is valid to humans. This may be due to the fact that many genetic changes are so-called recessive, i.e. cause changes only if both parents carry the same predisposition. Such disabilities are difficult to demonstrate by studies of populations, e.g. because these may not show in the first generation but much later.

Children of Hiroshima and Nagasaki

In Japan they call them pika-children, which means “children of the flash”. These are the children who were still in their mothers’ wombs in 1945 when first Hiroshima and then Nagasaki were hit by US atom bombs. Studies have shown a significant increase in mental retardation in children to mothers who were exposed to radiation when the bombs exploded. Of 1600 children in the study, 25 cases of mental retardation were found, as compared to five cases in a normal population.

Photo: BBC News

Photo: BBC News

Within a decade after the atom bombings, researchers had been able to document brain damage and mental retardation in children of mothers who were within two kilometres from the bomb epicentre. In recent years, new studies have been conducted using previous data, showing a significant connection between how many weeks pregnant the woman was and the severity of brain damage in the child. In particular, foetuses between 8-15 weeks were the most sensitive and developed the most severe brain damages. Mental retardation, underdeveloped head size, bad results in school and in IQ tests are examples of problems with these children.

Researchers at the Health Science Center of Texas University point out that the mental retardation is not necessarily a result of radiation alone, but also other factors may be important to include. The researchers mention that many of the pregnant women lost consciousness when the blast hit or when hit by falling debris from the explosion. Malnutrition, infections and severe stress and worry over the war could also have played a role.

The pika-children are grown-ups today, more than 60 years after the atom bombings. Many of them have had problems finding a place in Japanese society. They remind people around them of the terrible things that happened at the end of World War II – events that modern-day Japan rather would not think about every day. Many of them have been institutionalised and have had trouble getting education and jobs.

Health care after a nuclear explosion

A nuclear war would also have devastating consequences for the health care system. Hospitals will be destroyed, physicians and nurses killed and there will be an acute scarcity of medical resources. It would be extremely difficult to provide help for the surviving victims. Many of those who under normal circumstances could be saved, would inevitably die. In the Hiroshima bombing, 65 out of 150 doctors in the city were killed. At the largest hospital, run by the Red Cross, six doctors and ten nurses were healthy enough to work – only one completely uninjured. (4)

Health care after a nuclear explosion

The Shima Hospital of Hiroshima after the bombing (Hiroshima & Nagasaki Remembered)

A nuclear war will make it difficult for survivors to take care of their hygiene. The water will be contaminated, people will have to share tight quarters and it will be hard to keep a functioning waste management system. Insects and micro-organisms with a high tolerance to radioactivity will flourish. Bad hygiene and an increase of insects and vermins will lead to an increase of infectious diseases, which may lead to epidemics and pandemics.


Nuclear weapons and the human psyche

Nuclear weapons and the human psycheWe talk a lot about the effects of nuclear weapons on human health, but it is also important to ask what effects the knowledge of the world’s nuclear arsenals and their destructive power may have on the human psyche. Do we really feel okay about living under the constant threat of annihilation posed by nuclear weapons? Many of us may not even have the energy to think about it, because the idea seems frightening, abstract and overwhelming.

Even though nuclear weapons are high-technological devices, we have to remember that in the end it is man who holds the finger on the trigger; it is man who has developed these weapons and who controls them and has the capacity to launch them – and get rid of them. History shows that on a number of occasions man has been a hair’s breadth from using nuclear weapons by mistake, due to human errors and misinterpretations. How would it feel to be the one responsible for life and death – for the “to be or not to be” of mankind?

Only twice during the nuclear age have nuclear weapons been used in war: in Hiroshima and Nagasaki in August 1945. Close to 200 000 people were killed, but many survived. The Japanese call these survivors of the bomb Hibakusha. Today, many of the Hibakusha still alive travel the world to tell about their experience and memories. Many of them tell sad stories of exclusion and social stigmatisation – of how society has rather not seen and offered a place to them, since they carry the memory of the terrible things that affected Japan in 1945.


  1. World Health Assembly, Resolution WHA 36.28, 16 May 1983. Effects of nuclear war on health and health services. WHO Geneva 1984 ISBN 92 4 156080 0
  2. IPPNW and IEER: International Commission to Investigate the Health and Environmental Effects of Nuclear Weapons Production, reported in “Radioactive heaven and Earth: The health and environmental effects of nuclear weapons testing in, on and above the Earth.” The Apex Press, New York, 1991.
  3. Radiation and Human Health, International Campaign to Abolish Nuclear Weapons, fact sheet.
  4. John Hersey. Hiroshima. New York: Vintage Books, 1989

This page was last revised: 2013-01-14