Medical Consequences

A nuclear explosion can cause damage to human beings in a number of ways – immediately and in the longer term.

According to the Hippocratic oath, every physician pledges to serve his/her neighbor 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”.

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.


Hiroshima 1945

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.

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.

Radiation related injuries

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 alpha and beta radiation in the delayed 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 formation and infection defence in the bone marrow are particularly sensitive to radiation.

Hiroshima_girlIonising radiation also causes damage to DNA: the genetic material in living cells. A cell can repair certain levels of damage in its chromosomal DNA, especially at low levels of damage. However, faulty repairs can occur and may lead to proliferation of abnormal cells, which then form a cancer. Such cancers will generally take many cell generations to develop, and it may be several decades before the cancer is detected.

At higher levels of radiation exposure, cell death results. In parts of the body where cell turnover is normally high, such as the gastrointestinal tract and bone marrow, cells may not be replaced quickly enough, and tissues fail to function. This can be fatal.

The higher the dose of radiation, the sooner the symptoms will develop. Depending on the amount of radiation, three syndromes appear in human beings exposed to radioactivity:
The first syndrome concerns the blood-forming organs of the body. The bone marrow is damaged, decreasing its capacity to form white blood cells and blood platelets. Since the white blood cells defend the body against infections, the radiation victim becomes very sensitive to infection. The platelets bring about the coagulation of the blood, so a decrease in their number will increase bleeding. Thus, the risks are great that the victim will bleed to death. Depending on how much the bone marrow is damaged and how the victim is treated, he/she may return to health. Otherwise, death comes within a few months.

At a higher dose of radiation, the syndrome concerning the stomach and digestive system appears. It is characterised by nausea, vomiting, bleeding diarrhoea, dehydration and high fevers. The radiation victim dies within 1-2 weeks as a result of blood poisoning, intestinitis and disturbed water balance.

The third and gravest syndrome is the one that concerns the central nervous system (brain). The symptoms are headache, weariness, apathy, muscle tremors, coma, seizures and shock. This syndrome is an effect of high doses of radiation and inevitably ends in death within a few days.

The unit Gray indicates the absorbed radiation dose. In earlier writings, the unit Rad was often used, equalling 0,01 Gray. Since different types of radiation (alpha, beta and gamma) have different biological effects, in medical context the unit Sievert (Sv) is most commonly used to measure the biological effects of radiation.

The unit is named after Rolf Sievert, a former radiophysicist at the Stockholm based Karolinska Institute. Sievert is a large unit – 1 Sv can cause acute radiation sickness. Hence, the dose is often expressed in millisievert: 1 mSv 0 0,001 Sv. When indicating the radiation dose, a full body dose is usually referred to – that is, when the whole body is exposed to radiation. Lethal full body dose for a human being is considered in the area 3-5 Sv.

Dose (in Sievert) Health effect Time to onset (without heath care)
0,05-0,1 Sv Changes in blood chemistry
0,5 Sv Nausea Hours
0,55 Sv Fatigue
0,7 Sv Vomiting
0,75 Sv Hair loss 2-3 weeks
0,9 Sv Diarrhea
1 Sv Hemorrhage
4 Sv Possible death Within 2 months
10 Sv Destruction of intestinal lining
Internal bleeding
Death 1-2 weeks
20 Sv Damage to central nervous system
Loss of consciousness Minutes
Death Hours – days

Source: US Environmental Protection Agency: Radiation Protection

Radioactive fallout

The radioactive material  left behind by the nuclear weapon eventually falls to the ground as particles. This is called radioactive fallout and comes in three different categories: local, regional or global fallout.

In local fallout, the radioactive particles are spread downwind and fall to the earth within days. In some of the affected areas, the radioactive doses can be directly lethal to exposed humans.

The particles destined to become regional fallout go directly into the troposphere (the layer of air closest to the earth) after the explosion and then fall down during the span of some weeks. This fall-out can lead to damage in humans and, in the long run, to an increase in the numbers of cancer cases and genetic damage. People eating food, drinking water and breathing contaminated air suffer the effects of the fallout.

Some of the radioactive particles rise at the explosion to the stratosphere where they spread around the earth to slowly fall or rain down within months or even years as global fallout. This is caused mainly by larger nuclear weapons and when the explosion happens in the atmosphere rather than on the ground. The radioactivity decays somewhat before reaching the earth, but some radioactive substances have a half-life of thousands or millions of years – that is, the time it takes for the radioactivity to decrease by half.

This means the global fallout can cause health effects for a very long time. Cesium-137 and radioactive Iodine are examples of radioactive substances that enter the food chain and hence affect people’s health.

The cancer risk

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 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.

Reproductive health

In areas close to nuclear test sites as well as after the bombings of Hiroshima and Nagasaki, an increase in fetal 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.

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.

Health care after a nuclear explosion

We always expect there to be a doctor when we fall ill. A phone call to the health care centre or in the worst case an ambulance to the emergency room should be the only thing needed to get in touch with competent medical staff. But what happens if a nuclear explosion has razed all hospitals and care centres in town, if all streets are more or less destroyed, if all electronic equipment is knocked out and hundreds of thousands of people need health care? What happens when hundreds or thousands of doctors, nurses and other medical staff have been killed or too badly injured to work to save the lives of others?

When the atom bomb was dropped on Hiroshima on 6 August 1945, there were about 150 doctors in the city. Of these, 65 died in the explosion and almost all of the others were badly injured. At the largest hospital, run by the Red Cross, six doctors and ten nurses were healthy enough to work – only one completely uninjured: Doctor Sasaki. Injured, bleeding, burned, vomiting, ragged, crying and screaming people poured in en masse at the hospital.

Medicin7At least ten thousand people came to the hospital. Dr Sasaki had no chance to save them all – not even a fraction of them. He did what he could to stop people from bleeding to death, but soon his patient started developing terrible symptoms of radiation sickness: uncontrolled bleedings, severe problems with internal organs, hair loss and extreme susceptibility to infections.

It was practically impossible to save anyone, since all hospitals in the city had been destroyed and almost all medical staff had been killed or injured.


The_patient's_skin_is_burned_in_a_pattern_corresponding_to_the_dark_portions_of_a_kimono_-_NARA_-_519686The massive heat wave created by the nuclear explosion causes severe burns. Heat moves at the speed of light, and it is impossible to find protection from the thermal pulse unless warned in advance. The thermal radiation leads to immediate burns on bare skin. Burning clothes will also cause severe burns. Treatment of burns is among the most resource-demanding treatments. Treating all burns victims will be one of the greatest challenges to the health system in the event of nuclear war.

Also under normal circumstances, the number of hospital beds for treatment of severe burns is most limited, around the world. In Sweden, it is possible to treat approximately twenty badly burned patients at a time with specialised intensive care. In all of Europe, possibly some hundreds. And this goes for ordinary situations, when neither hospitals nor medical staff have been knocked out by a nuclear explosion.

In Nagasaki, it was estimated the 95 percent of all victims suffered from burns. In Hiroshima, the corresponding number was 60 percent. This data derives from the Manhattan Engineer District (MED), that estimate much lower numbers of dead and injured than do many others. MED estimate 69 000 injured in Hiroshima and 25 000 in Nagasaki.

It does not take a rocket scientist to figure out that if 95 percent of 25 000 injured are suffering from severe burns, the intensive care for burn victims at hospitals will not suffice. Neither can one expect to transport victims to intensive care in other countries after a nuclear explosion, which can be done under ordinary circumstances.

The world of rats and cockroaches

It is often said that the only living things surviving a nuclear war would be rats and cockroaches. It may not be entirely true, but many vermin and insects stand a greater chance of surviving than us humans.

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 vermin will lead to an increase of infectious diseases, which may lead to epidemics and pandemics. The use of nuclear weapons would also lead to an nuclear winter with cold climate and bad harvest. The food and water scarcity would in turn lead to global famine, leading to armed conflicts over scarce resources. It has also been observed that famines are often followed by pandemics of infectious disease.


Last update: February 9, 2015