Radiobiology Hall 14: Radiologic Terrorism (Completed)

Transcription

1 Radiobiology Hall 14: Radiologic Terrorism (Completed) What are a few of the possible scenarios of radiologic terrorism? 1. Detonation of a nuclear major city 2. An attack on a nuclear power station 3. The detonation of a "dirty bomb"/ Radiologic Dispersal Device (RDD) 4. Hidden Radiation Exposure Device (RED) The following are possible scenarios of radiologic terrorism: Highely unlikely (but not impossible) because several portable suitcase bombs are said to be missing following the break-up of the former Soviet Union 1. Detonation of a nuclear major city Thousands would be killed by the heat and the blast Hundreds to thousands would be ill/killed due to ARS 2. An attack on a nuclear power station Long-term risks to leukemia and solid cancers 3. The detonation of a "dirty bomb"/ Radiologic 4. Hidden Radiation Exposure Device (RED) What effects would the detonation of a nuclear Page 1

2 major city have? The following are possible scenarios of radiologic terrorism: 1. Detonation of a nuclear major city Highly unlikely (it is said (untested) that facilities are too strong to be detonated by even a fully fueled airliner Unlikely high enough doses for ARS Long-term risk of leukemia and solid cancer (ingesting/inhaling radioactive material) 2. An attack on a nuclear power station 3. The detonation of a "dirty bomb"/ Radiologic Chaos Economic loss because of cleanup would be a long and slow process 4. Hidden Radiation Exposure Device (RED) What effects would an attack on a nuclear power station have? The following are possible scenarios of radiologic terrorism: Highly likely probability Unlikely high enough doses for ARS 1. Detonation of a nuclear major city Minimal long-term risk of leukemia/solid cancers cannot be ruled out Chaos, psychological terror, widespread fear 2. An attack on a nuclear power station Page 2

3 3. The detonation of a "dirty bomb"/ Radiologic 4. Hidden Radiation Exposure Device (RED) What effects would the detonation of a "Dirty Bomb" / Radiologic have? The following are possible scenarios of radiologic terrorism: Highly likely probability Unlikely high enough doses for ARS 1. Detonation of a nuclear major city Fear psychological chaos Very small long-term possibility of radiation-induced malignancies 2. An attack on a nuclear power station 3. The detonation of a "dirty bomb"/ Radiologic 4. Hidden Radiation Exposure Device (RED) What effects would the detonation of a Hidden Radiation Exposure Page 3

4 Device (RED) have? What are some possible sources of radioactive material that could be used to build a "Dirty Bomb" or Radiologic Dispersal Device (RDD)? 1. Household smoke detectors ---contain a tiny amount of americium-241 (few thousand bacquerels) ---americium-241 is an alpha emitter which is only dangerous if inhaled or ingested 2. Moisture Density Gauges (used by engineers, contractors, and highway departments for compaction control of soil aggregate, concrete, and full depth asphalt) ---small amounts of americium-241 and cesium-137 (more than 23,000 are in regular use in the U.S. with around 50 reported as missing/stolen per year) 3. Cesium-137 sources are widely used in hospitals and medical centers year half-life ---vaporizes readily ---can be widely spread by an explosive device (19 small cesium-137 sources with an activity level of about 22 GBq were reported missing from a medical center in North Carolina in 1998) The health effects of radiation can be divided Deterministic effects only occur at relatively high doses and result from the killing of many cells in a tissue or organ. Page 4

5 into two types: deterministic and stochastic. Above a tissue-specific dose threshold, the severity of the damage increases with increasing dose as more and more cells are killed. Describe deterministic effects? As long as the dose threshold is not exceeded, the effect will not be seen. Some deterministic effects do not manifest until years later (e.g., cataract, fibrosis) and are therefore known as late effects. By contrast, those that manifest in days to weeks are called early effects, or acute effects. A sufficiently large radiation dose over a short time can result in the ARS, which may result in death. This results from the killing of many cells in the bone marrow or lining of the intestines. Examples of this occurred at Hiroshima and Nagasaki, and also following the reactor accident at Chernobyl. A dose of several grays is needed to result in these effects, which is possible following the detonation of a nuclear weapon or the meltdown of a nuclear reactor, but would be unlikely to occur following a dirty bomb. The health effects of radiation can be divided into two types: deterministic and stochastic. Describe stochastic Stochastic effects, of which carcinogenesis is the most important, are all-or-nothing effects (i.e., the severity of the effect does not alter the magnitude of the dose, although the probability of the event occurring does increase with dose). Page 5

6 effects? For example, if one person is exposed to 0.1 Gy and another is exposed to 1 Gy, the person exposed to the higher dose would have a greater probability of having cancer; but if both contracted the same malignancy, it would not be more severe in the person who received the higher dose. Cancer is an all-or-nothing event. The other important characteristic of a stochastic effect is that there is believed to be no threshold in dose (i.e., even the smallest dose carries some level of risk, which however becomes vanishingly small at very low doses). Which type of irradiation of a person are considered "external" exposures and could be dispersed by either a Radiologic or an Radiation Exposure Device (RED)? A Radiologic Dispersal Device (RDD) that scatters radioactive materials over a wide area, could result in people nearby becoming "contaminated". Gamma rays Beta rays Alpha Beta Gamma Radioactive contamination may consist of radionuclides that emit,, radiation or a combination of all three? Page 6

7 The most important distinction between the three nucleotides (alpha, beta, and gamma) is their ability to penetrate. Describe the ability to penetrate for the Alpha particle? The most important distinction between the three nucleotides (alpha, beta, and gamma) is their ability to penetrate. Alpha-particles have a very short range and cannot even penetrate the outer layer of skin. Consequently, they cause harm only if they are internalized by inhalation, ingestion, or absorption through intact skin or through a wound. Examples of Alpha-emitters include polonium-210 that was used to "poison" the Russian defector, Alexander Litvinenko. Beta-particles can penetrate several centimeters into tissue. Describe the ability to penetrate for the Beta particle? The most important distinction between the three nucleotides (alpha, beta, and gamma) is their ability to penetrate. Gamma rays are so penetrating that they can pass right through the body. Describe the ability to penetrate for the Gamma particle? External contamination refers to radioactive material on the surface of the body. Removing the clothing, which should be placed in a plastic bag and labeled. Most external Page 7

8 contamination (up to 90%), following an event like a dirty bomb, can be disposed of by? External contamination refers to radioactive material on the surface of the body. Most external contamination (up to 90%), following an event like a dirty bomb, can be disposed of by removing the clothing, which should be placed in a plastic bag and labeled. Open Wounds Next is the nose and mouth, followed by intact skin. Contaminated areas should be carefully washed with soap and water. The top priority, after removal of clothing, to decontaminate is because they offer a fast direct route for internalizing radioactive materials and transportation to critical organs. What are some routes of entry that leads to internal contamination? 1. Inhalation into the lungs 2. Ingestion into the GI tract 3. Percutaneous or Transdermal absorption through intact skin and particularly open wounds Iodine tends to remain in the body in the? Thyroid Page 8

9 Plutonium or Americium tends to remain in the body in the? Not much can be done to counter the effects of internal contamination, except in a few cases... one of which is radioactive iodine. Bones Stable iodine (in the form of potassium iodine) can be taken within 4 to 6 hours of contamination. This saturates binding sites in the thyroid and inhibits the incorporation of radioactive iodine. How is the internal effects of iodine countered? Internal iodine can cause what effects, as was seen in the Chernobyl experience? What FDA approved drug is used to counter the effects of Cesium-137 (possible "dirty bomb" material) by blocking its uptake? Hypothyroidism and can also result in cancer. Especially important in children and in the developing embryo or fetus. Prussian Blue (ferric III hexacyanoferrate II) Page 9