Effects of nuclear explosions on human health

Melted and fused pieces of metal (including coins that were in people's pockets) from the Atomic bombings of Japan. The melting of metal like this occurred during the ensuing fires and firestorms, long after the bombs had exploded.

The main causes of death and disablement in this state are thermal burns and the failure of structures resulting from the blast effect. Injury from the pressure wave is minimal in contrast because the human body can survive up to 2 bar (30 psi) while most buildings can withstand only a 0.8 bar (12 psi) blast. Therefore, the fate of humans is closely related to the survival of the buildings around them.[7]

• over 0.8 bar (12 psi) - 98% dead, 2% injured
• 0.3 - 0.8 bar (5-12 psi) - 50% dead, 40% injured, 10% safe
• 0.14 - 0.3 bar (2-5 psi) - 5% dead, 45% injured, 50% safe[7]

The "prodromal syndrome" is not a diagnosis, but the technical term used by health professionals to describe a specific group of symptoms that may precede the onset of an illness. For example, a fever is "prodromal" to measles, which means that a fever may be a risk factor for developing this illness.

Bone marrow death is caused by a dose of radiation between 2 and 10 Gray and is characterized by the part of the bone marrow that makes the blood being broken down. Therefore, production of red and white blood cells and platelets is stopped due to loss of the blood-making stem cells (4.5 Gray kills 95% of stem cells). The loss of platelets greatly increases the chance of fatal hemorrhage, while the lack of white blood cells causes infections; the fall in red blood cells is minimal, and only causes mild anemia.[9]

The exposure to 4.5 Gray of penetrating gamma rays has many effects that occur at different times:

In 24 hours:[9]

• vomiting
• diarrhea

These will usually abate after 6–7 days.

Within 3–4 weeks there is a period of extreme illness.[9]

• severe bloody diarrhea, indicating intestinal disorders causing fluid imbalance
• extensive internal bleeding
• sepsis infections

The peak incidence of acute BM death corresponds to the 30-day nadir in blood cell numbers. The number of deaths then falls progressively until it reaches 0 at 60 days after irradiation. The amount of radiation greatly affects the probability of death. For example, over the range of 2 to 6 Gray the probability of death in untreated adults goes from about 1% to 99%, but these figures are for healthy adults. Therefore, results may differ, because of the thermal and mechanical injuries and infectious conditions.[9]

Gastrointestinal death is caused by a dose of radiation between 10 and 50 Gray. Whole body doses cause damage to epithelial cells lining the gastrointestinal tract and this combined with the bone marrow damage is fatal. All symptoms become increasingly severe, causing exhaustion and emaciation in a few days and death within 7–14 days from loss of water and electrolytes.[9]

The symptoms of gastrointestinal death are:[9]

• gastrointestinal pain
• anorexia
• nausea
• vomiting
• diarrhea

Central nervous system death is the main cause of death in 24–48 hours among those exposed to 50 Gray.[9]

The symptoms are:[9]

• vomiting
• nausea
• diarrhea
• drowsiness
• lethargy
• tremors
• delirium
• frequent seizures
• convulsions
• heat prostration
• coma
• respiratory failure
• death

The skin is susceptible to beta-emitting radioactive fallout. The principal site of damage is the germinal layer, and often the initial response is erythema (reddening) due to blood vessels congestion and edema. Erythema lasting more than 10 days occurs in 50% of people exposed to 5-6 Gray.[9]

Other effects with exposure include:[9]

• 2–3 Gray—temporary hair loss
• 7 Gray—permanent epilation occurs
• 10 Gray—itching and flaking occurs
• 10–20 Gray—weeping blistering and ulceration will occur

The lungs are the most radiosensitive organ, and radiation pneumonitis can occur leading to pulmonary insufficiency and death (100% after exposure to 50 Gray of radiation), in a few months.

Radiation pneumonitis is characterized by:[9]

• Loss of epithelial cells
• Edema
• Inflammation
• Occlusions of airways, air sacs and blood vessels
• Fibrosis

A single dose of 1–2 Gray will cause temporary damage and suppress menstruation for periods up to 3 years; a dose of 4 Gray will cause permanent sterility.[9]

A dose of 0.1 Gray will cause low sperm counts for up to a year; 2.5 Gray will cause sterility for 2 to 3 years or more. 4 Gray will cause permanent sterility.[9]

The timespan for developing this symptom ranges from 6 months to 30 years to develop but the median time for developing them is 2–3 years.[9]

• 2 Gray of gamma rays cause opacities in a few percent
• 6-7 Gray can seriously impair vision and cause cataracts

Cancer induction is the most significant long-term risk of exposure to a nuclear bomb. Approximately 1 out of every 80 people exposed to 1 Gray will die from cancer, in addition to the normal rate of 20 out of 80. About 1 in 40 people will get cancer, in addition to the typical rates of 16-20 out of 40. Different types of cancer take different times for them to appear:[9]

• 2 years for leukemia to appear
• 20 or more years for skin cancer or lung cancer

A 1 Gy dose of radiation will cause between 0 and 20 extra cases of perinatal mortality, per 1,000 births and 0-20 cases per 1000 births of severe mental sub-normality. A 0.05 Gy dose will increase death due to cancer 10 fold, from the normal 0.5 per 1000 birth rate to a rate of 5 per 1,000. An antenatal dose of 1 Gy in the first trimester causes the lifetime risk of fatal cancer sometime in the child's life to increase from c. 25% in non-exposed humans to 100% in the first trimester after exposure.[9]

Exposure to even relatively low doses of radiation generates genetic damage in the progeny of irradiated rodents. This damage can accumulate over several generations.[10] No statistically demonstrable increase of congenital malformations was found among the later conceived children born to survivors of the Nuclear weapons at Hiroshima and Nagasaki.[11][12][13] The surviving women of Hiroshima and Nagasaki, that could conceive, who were exposed to substantial amounts of radiation, went on and had children with no higher incidence of abnormalities than the Japanese average.[14][15]

It was assumed in the 1983 book Medical Consequences of Radiation Following a Global Nuclear War that, although not caused by radiation, one of the long-term effects of a nuclear war would be a massive increase in infectious diseases caused by fecal matter contaminated water from untreated sewage, crowded living conditions, poor standard of living, and lack of vaccines in the aftermath of a nuclear war, with the following list of diseases being cited:[7]

• Dysentery
• Typhoid
• Infectious hepatitis
• Salmonellosis
• Cholera
• Meningococcal meningitis
• Tuberculosis
• Diphtheria
• Whooping cough
• Polio
• Pneumonia

However although what the authors describe are conditions already prevalent in many of the world's city slums, it is inconceivable why people would try to remain living in crowded conditions by reverting to slum lifestyles, during or after a nuclear war. As many cities would already be destroyed, with urban life, slum or otherwise, this would serve no benefit to inhabitants.

There would be billions of disease carrying vectors, in the form of city residents,[16] lying deceased in cities caused by the direct nuclear weapons effects alone, with the surviving few billion people spread out in rural communities living agrarian lifestyles, with the survivors therefore posing a way of living far less prone to creating the crowded slum living conditions required for infectious diseases to spread. Moreover, as reported in a paper published in the journal Public Health Reports, it is also one of a number of prevalent myths that infectious diseases always occur after a disaster in cities.[17][18]

Epidemics seldom occur after a disaster, and dead bodies do not lead to catastrophic outbreaks of infectious diseases. Intuitively, epidemic diseases, illnesses, and injuries might be expected following major disasters. However, as noted by de Goyet, epidemics seldom occur after disasters, and unless deaths are caused by one of a small number of infectious diseases such as smallpox, typhus, or plague, exposure to dead bodies does not cause disease ... Cholera and typhoid seldom pose a major health threat after disasters unless they are already endemic.