At the time of writing of this article, exactly 70 years have passed since the atomic bomb was launched on Hiroshima and Nagasaki in August 1945 claiming the life of at least 200000 people (Truly a weapon of mass destruction (WMD))
- The mechanism of the A-bomb is nuclear fission ( The technique was developed by Fermi, Oppenheimer and al. in the “Manhattan” project )
- The bomb dropped on Hiroshima contained 141pounds (64Kg) of enriched uranium exploded with an energy of 15 Kilotons of TNT ( Nagasaki =20Kilotons) ( To achieve explosion a critical mass must be reached which is why one part was ignited to assemble with the other at the very last minutes before releasing the bomb )
- During nuclear fission, uranium starts to breakdown into lower weight elements (isotopes) in a process called radioactive decay and emits radiation (alpha waves…).
- At the time of explosion , enormous amounts of energy are released:
1 – in the form of thermal radiation (mainly infrared rays)
2 – by releasing neutrons and gamma rays: in the first millionth of a second moving at high speeds
On the skin the effects can be measured as follows:
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Immediate effects:
- Burns due to invisible thermal radiation after fireball interaction with shock wave = these are called flash burns. They occur on the skin directly exposed to the radiation
- they occur then the heat is absorbed such as by clothing or the skin (skin covered by white clothing was protected)
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Types :
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3rd degree burns * (received amount of thermal radiation for a 20 Kiloton bomb is 8 cal/cm2 (which corresponds to a distance of up to 2.7 km)
- The damage affects the whole skin (epidermis, dermis, subcutaneous fat)
- The skin appears leathery and can be purple, black or white
- Physical examination shows complete loss of sensation and is painless
- Treatment consists of skin grafting . (Natural healing occurs from the wound edges and is slow)
- If more than 25% of the body surface area is involved, shock is likely and supportive measure such as fluid administration and heat insulation can be needed
- Healing inevitably results in scarring with possible formation of keloids
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3rd degree burns * (received amount of thermal radiation for a 20 Kiloton bomb is 8 cal/cm2 (which corresponds to a distance of up to 2.7 km)
- Burns due to invisible thermal radiation after fireball interaction with shock wave = these are called flash burns. They occur on the skin directly exposed to the radiation
After the bombing, 90% of the 200 medical doctors in Hiroshima were incapacitated and of the 45 hospitals and dispensaries, only 3 remained functional
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2nd degree burns * 5 cal/cm2 (or a distance of up to 3.2 km)
- The skin appears purple, black or white and is painful when touched. Blisters are typically present on the surface
- They can be divided in two subtypes
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superficial
- part of the upper dermis is involved but the adnexal structures (hair follicles) are preserved
- healing resolves without scarring
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deep
- the deep dermis is involved
- Healing results in scarring with possible formation of keloids
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superficial
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1st degree burns * (2.5 cal/cm2 (or a distance of up to 4.3 km)
- the skin appears appears red (it is the type typically found in sunburn)
- the epidermis is affected and the skin is painful
- Treatment is mainly supportive ( see management of sunburn )
- Healing is uneventful within a few days
Bodies in the close vicinity of the bomb (500yards) where either transformed into carbon (vaporized) or suffered lethal 4th degree burns (involvement of the muscle or bone below the skin) (due to short traveling X-rays which are absorbed in the air generating heat)
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Delayed effects (years):
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Basal Cell Carcinoma (BCC)
- Ionizing radiation by neutrons and gamma rays causes the generation of reactive oxygen species (ROS) which damages the DNA of the cell. ( Human Beings irradiated in the close vicinity of the bomb (500yards) were immediately killed )
- DNA is most active in rapidly dividing cells (blood cell, gut, fetuses). In the skin the most active cell are in the basal layer of the epidermis, where the stem cells for epidermal barrier renewal are located. ( Sugiyama et al. http://www.ncbi.nlm.nih.gov/pubmed/24754560 )
- Newborns had a 15 times excessive relative risk (ERR) of developing the condition
- No effects were recorded for Squamous Cell Carcinoma (ERR of 0.71) or other skin cancers.
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Basal Cell Carcinoma (BCC)
*It is difficult to evaluate the distance to ground zero to determine the gravity of the burns as some shielding (eg buildings) absorbed some of the radiation.
This article does not give a judgement or a political analysis, but only examines the cutaneous effects of nuclear fission.
Bibliography: www.nuclearweaponarchive.org