Nuclear Fallout of Nagasaki

1. Nuclear FalloutofNagasaki Nuclear FalloutofNagasaki

2. History • On 9 August 1945, Nagasaki was the target of t he world's second atomic bomb attack at 11:02 a.m., when the north of the city was destroyed and an estimated 39,000 people were killed outright with another 75,000 believed to have died of bomb-related causes in the decades that followed. • The Nagasaki bomb, code-named "Fat Man", dropped by the Boeing B-29 Bockscar was more powerful (22 kilotons of TNT as opposed to 15) than the bomb dropped on Hiroshima three days earlier ("Little Boy"), and was an implosion-type plutonium bomb, whereas the Hiroshima bomb was a gun-type uranium bomb.

3. History cont. • Mushroom cloud from the nuclear explosion over Nagasaki rising 60,000 feet into the air on the morning of August 9, 1945 • The ferocious heat and blast indiscriminately slaughtered its inhabitants. Even the people who managed to survive continue to this day to suffer from late effects.

4. The required conditions for Acute Radiation Syndrome (ARS) are: • The radiation dose must be large (greater than 0.7 Gray (Gy)1, 2 or 70 rads). • Mild symptoms may be observed with doses as low as 0.3 Gy or 30 rads. • The dose usually must be external (the source of radiation is outside of the patient’s body). • Radioactive materials deposited inside the body have produced some ARS effects only in extremely rare cases. • The radiation must be penetrating (i.e., able to reach the internal organs). • High energy X-rays, gamma rays, and neutrons are penetrating radiations. • The entire body (or a significant portion of it) must have received the dose3. • Most radiation injuries are local, frequently involving the hands, and these local injuries seldom cause classical signs of ARS. • The dose must have been delivered in a short time (usually a matter of minutes). • Fractionated doses are often used in radiation therapy. These are large total doses delivered in small daily amounts over a period of time. Fractionated doses are less effective at inducing ARS than a single dose of the same magnitude

5. Acute or Short Term Effects • Humans receiving an acute incapacitating dose (30 Gy) will have their performance degraded almost immediately and become ineffective within several hours. However, they will not die until 5 to 6 days after exposure assuming they do not receive any other injuries. • Individuals receiving less than a total of 1.5 Gy will not be incapacitated. Between those two extremes, people receiving doses greater than 1.5 Gy will become disabled; some will eventually die.

6. The three classic ARS Syndromes are: • Bone marrow syndrome (sometimes referred to as hematopoietic syndrome) the full syndrome will usually occur with a dose between 0.7 and 10 Gy (70 – 1000 rads) though mild symptoms may occur as low as 0.3 Gy or 30 rads4. • The survival rate of patients with this syndrome decreases with increasing dose. The primary cause of death is the destruction of the bone marrow, resulting in infection and hemorrhage. • Gastrointestinal (GI) syndrome: the full syndrome will usually occur with a dose greater than approximately 10 Gy (1000 rads) although some symptoms may occur as low as 6 Gy or 600 rads. • Survival is extremely unlikely with this syndrome. Destructive and irreparable changes in the GI tract and bone marrow usually cause infection, dehydration, and electrolyte imbalance. Death usually occurs within 2 weeks. • Cardiovascular (CV)/ Central Nervous System (CNS) syndrome: the full syndrome will usually occur with a dose greater than approximately 50 Gy (5000 rads) although some symptoms may occur as low as 20 Gy or 2000 rads. • Death occurs within 3 days. Death likely is due to collapse of the circulatory system as well as increased pressure in the confining cranial vault as the result of increased fluid content caused by edema, vasculitis, and meningitis.

7. The four stages of ARS are: • Prodromal stage (N-V-D stage): The classic symptoms for this stage are nausea, vomiting, as well as anorexia and possibly diarrhea (depending on dose), which occur from minutes to days following exposure. The symptoms may last (episodically) for minutes up to several days. • Latent stage: In this stage, the patient looks and feels generally healthy for a few hours or even up to a few weeks. • Manifest illness stage: In this stage the symptoms depend on the specific syndrome and last from hours up to several months. • Recovery or death: Most patients who do not recover will die within several months of exposure. The recovery process lasts from several weeks up to two years.

8. Chronic or Long Term Effects • Strictly speaking the correct name for "radiation sickness" is acute radiation syndrome. A chronic radiation syndrome does exist but is very uncommon; this has been observed among workers in early radium source production sites and in the early days of the Soviet nuclear program. While a short exposure can result in acute radiation syndrome, it requires a prolonged high level of exposure to cause the chronic syndrome. • Radiation caused illness and death after the bombings of Hiroshima and Nagasaki in about 1% of those exposed who survived the initial explosions. The casualty rate due to radiation was higher in Hiroshima, because although Fat Man (the bomb used at Nagasaki) had a higher yield than Little Boy (the bomb used at Hiroshima), Fat Man was a plutonium weapon, which is actually much less radioactive than a uranium weapon of equal yield (except at the moment of critical mass). Both bombs were airbursted, minimizing nuclear fallout (which otherwise would have killed many more).

9. Long Term Effects cont. • Late or delayed effects of radiation occur following a wide range of doses and dose rates. Delayed effects may appear months to years after irradiation and include a wide variety of effects involving almost all tissues or organs. Some of the possible delayed consequences of radiation injury are life shortening, carcinogenesis, cataract formation, chronic radiodermatitis, decreased fertility, and genetic mutations. • In multicellular organisms, mutations can be subdivided into germline mutations, which can be passed on to descendants and somatic mutations. The somatic mutations cannot be transmitted to descendants in animals. • If there is a mutation or other genetic change in the germline, then the change can be passed to offspring. For example, sex cells, such as the sperm or the egg, are part of the germline.

10. Illnesses Caused • Carcinogenesis (meaning literally, the creation of cancer) is the process by which normal cells are transformed into cancer cells. • Radiodermatitis is a skin disease associated with prolonged exposure to radiation. It is most commonly found in people working in the medical field who worked extensively with imaging devices. New cases are less common now than they were at the advent of these technologies, as the long term impact of radiation is better understood.

12. Questions • What is another name for the bomb used in Nagasaki? • What was the date on which they bombed Nagasaki? • List the three classic Acute Radiation Syndromes (ARS). • State the four stages of ARS. • List the conditions required for ARS.

13. Questions • State three long term effects of radiation exposure. • Define the term carcinogenesis. • Name the two types of mutations which multicellular organisms can have. • Define somatic mutation. • Define germline mutation.

14. Answers • The name of the bomb was Fat Man. • The bomb on Nagasaki was dropped on August 9, 1945. • Three classic radiation syndromes are bone marrow, gastrointestinal and central nervous system syndrome. • The four stages of ARS are prodromal, latent, manifest illness stage and recovery or death. • Some conditions required for ARS are the radiation dose must be large enough, dose must usually be external, radiation must be penetrating. • Three long term effects are carcinogenesis, radiodermatitis and mutation. • Carcinogenesis (meaning literally, the creation of cancer) is the process by which normal cells are transformed into cancer cells. • Mutation can be germline or somatic. • The somatic mutations cannot be transmitted to descendants in animals. • If there is a mutation or other genetic change in the germline, then the change can be passed to offspring. For example, sex cells, such as the sperm or the egg, are part of the germline.