Submitted by Anonymous (not verified) on Sun, 2011-04-24 08:59.
Dose, Rem Effects
5
No observable effects
10
Difficult to demonstrate a higher incidence in fetal abnormalities or cancer effects below 10 rem dose. A 10 rem dose results in a 0.8% lifetime increase in developing cancer.
15
Threshold, blood and sperm abnormalities seen
25
Threshold, genetic effects demonstrated
70
A decrease in lymphocytes in peripheral blood chemistry profile after 24 hours indicating some bone marrow depression.
100
Hospitalization recommended
100
Acute symptoms include nausea, malaise, vomiting, and anorexia. Long term effects include a 5% cancer increase death risk, 1% genetic risk defects. The onset of acute symptoms vary with the individual but could be a few days at the low end of the dose (100 rem) or maybe an hour for doses above 200 rem. Most patients are without symptoms below 100 rem.
120
Abrupt decreases in sperm count, but recovery of natural fertility usually occurs after several months or a year
200
Bone marrow depression symptoms apparent. The onset of symptoms associated with bone marrow depression can vary with the individual and dose; but can be several weeks or even months after radiation exposure. These symptoms may occur weeks after the person has recovered from the initial onset of nausea and anorexia. Changes in the peripheral blood profile may occur as early as 24 hours after radiation exposure. Lymphocytes will be depressed most rapidly, and other leukocytes and thrombocytes will be depressed less rapidly. A 50% drop in lymphocytes in 24 hours indicates significant radiation injury. Symptoms include bleeding (hemorrhage) and anemia, diarrhea, fluid loss, and decreased resistance to infection, which become apparent several weeks after radiation exposure. Minimal treatment includes fluid replacement, antibiotics, and prevention of infection. More aggressive treatment includes bone marrow resuscitation therapy.
250
10% of people develop cataracts within several months
300
Epilation (hair loss)
350
Median lethal dose of radiation that will kill 50% of the exposed persons within 60 days without appropriate medical treatment. Mortality is low with aggressive therapy.
400
Continued loss of epithelial cells of the intestinal mucosa results in hemorrhage and marked fluid loss contributing to shock; these symptoms occur within 1 or 2 weeks after irradiation.
600
Almost 100% fatal within 60 days if untreated. Erythema occurs. Lymphocyte count decreases from normal level of about 2000 or 2500 to about 500 in 24 hours. Cognitive impairment.
800+
Rapid incapacitation. Symptoms may occur within an hour after exposure. Diarrhea, fever, electrolyte imbalance. Mortality rate high even with treatment.
2000
Onset of symptoms within minutes. Neurovascular symptoms occur within several hours to about 3 days after exposure. These include a steady deteriorating state of conscience with eventual coma and death.
The above table was constructed from the following two documents:
Medical Management of Radiological Casualties, 2nd edition, April 2003. Armed Forces Radiobiology Research Institute, Bethesda MD. A copy may be obtained from http://www.afrri.usuhs.mil/.
Disaster Preparedness for Radiological Professionals. 2002. American College of Radiology. Washington DC. See http://www.arc.org/.
Example: Cesium 137 in the PEAC tool
Let’s pull up Cesium 137 in the PEAC tool. Its chemical formula abbreviation is Cs 137. This is a man-made element which has been detected at nuclear power plants. Industrial uses include food irradiation, soil density testing, and radiography. The atomic number 137 means that the total number of protons plus neutrons is 137. The atomic weight is 136.907. Protons and neutrons do not have exactly the same mass so when the atomic weight is calculated, the number totals to 136.907 rather than an even 137.
Cesium 137 is radioactive. It emits a beta particle with maximum of 1.176 MeV (1.176 million electron volts per beta particle) kinetic energy. Accompanying this emission is 0.66164 MeV of gamma radiation. There is no alpha particle emission.
The activity of Cerium 137 is 86.6912 curies per gram. Radiation activity is usually measured in curies or microcuries [106 microcuries = 1 curie]. Activity is directly related to the number of disintegrations per unit time. One disintegration per second = 2.703 x 10-11 curies. [One disintegration per second = 2.703 x 10-5 microcuries]. Disintegration means that the cesium 137 has emitted a beta particle forming Barium 137. Barium 137 is stable and not radioactive.
The half-life of cesium 137 is 30.2 years. This means that after 30.2 years, half of the cesium 137 will have disintegrated forming barium 137. The half-life can be calculated directly knowing the activity and atomic weight.
MeV (million electron volts per particle or gamma emission) is a unit of energy. 1 MeV = 1.603 x 10-13 joules.
The relationship between MeV of energy and rem of radiation exposure is not easy to predict. Let us look at two cases, one in which the radioactive isotope is taken internally (by inhalation or ingestion) and the other case where the isotope is external to the body, but the person receives a radiation dose from the beta particles and gamma radiation.
Radioactive isotope inhaled or ingested: The U.S. Nuclear Regulatory Commission has codified the maximum annual exposure to radiation workers and general public from inhalation and ingestion of radioactive isotopes. This is in Title 10 of the Code of Federal Regulations, Part 20 Appendix B and is repeated in the PEAC tool. The worker exposure limit listed in 10 CFR part 20 is based on 5 rem/year, and the general public exposure limit is based on 0.1 rem/year.
Radioactive isotope external to human body: The degree of penetration of beta particles into the human body from the isotope depends on the distance the particle travels and its kinetic energy. A beta particle of 1.176 MeV kinetic energy can travel slightly over 1 meter in air or several centimeters in water (or several centimeters into human flesh). Clinically, beta particles produce a burn indistinguishable from a thermal burn. Gamma radiation on the other hand is much more penetrating and can produce symptoms like that listed in table 1. Neither gamma radiation nor beta particles from an external source leave residual radiation in the body.
From 10 CFR part 20, the annual limit on intake (ALI) of Cesium 137 into the body corresponding to a 5 rem dose is 200 microcuries per year. The ALI takes into account exposure to any daughter isotopes produced in the body (some radioactive isotopes have radioactive daughter species). From the ALI value, the derived air concentration (DAC) for inhalation is computed assuming a worker exposure of 2000 hours per year and a breathing rate of 20 liters per minute. The general public is based on a 0.1 rem annual exposure limit, 24 hours per day and 365 days per year. The drinking water limit is based on 730 liters intake per year.
Annual Limit on Intake of Cesium 137 for 5 rem dose: 200 microcuries
Max. Occupational Derived Air Concentration, 5 rem dose/year: 6 x 10-8 microcuries/ml
Max Public Air Concentration, 0.1 rem dose/year: 2 x 10-9 microcuries/ml
Max Public Water Concentration, 0.1 rem dose/year: 2 x 10-5 microcuries/ml.
If there is more than one radioactive isotope in the air or water, all isotopes must be considered as contributing to the radiation dose.
The external radiation exposure calculation is a little complicated. The dose depends upon whether the cesium 137 comes from a point source some distance away from the emergency responder, is uniformly distributed in the air (the responder is assumed to have an air pack), or is distributed as dust on the responder’s protective suit. For example, let us calculate the radiation dose received by a person located one meter away from one gram of cesium 137. The first step is to calculate a flux (units: gamma photon radiation/sq. meter-second) at a distance one meter from the source. Then the flux is converted to a dose rate (units: rem/hour) using lookup tables that are located in the following reference source:
“Neutron and Gamma-Ray Flux-to-Dose Rate Factors”, American National Standard, ANIS/ANS-6.11. 1977.
Other reference sources are available; this is not the only one. The flux itself is computed using a formula which has constants pulled from lookup tables. The calculations are too complicated to walk through and explain in this write-up but when we are done, the flux at one meter away is computed to be 2.6 x (10)11 gamma photons/m2-s, and the radiation dose rate is 38 rem/hour. A person one meter away might receive 114 rem dose after 3 hours. This is enough to manifest itself with clinical symptoms (nausea, may appear several days later), a decrease in blood lymphocytes (see table 1), and increased cancer risk later in life.
The gamma radiation flux (and the dose rate) falls off as the inverse square of the distance from the source. This means that if the 1-gram gamma radiation source were located 10 meters away, the dose rate would be only 0.4 rem/hour. On the other hand, if a person were dressed in a Level A protection suit and the suit becomes covered with cesium 137 dust, the dose rate can be very high. Additional Reading
Medical Management of Radiological Casualties, 2nd edition, April 2003. Armed Forces Radiobiology Research Institute, Bethesda MD. A copy may be obtained from http://www.afrri.usuhs.mil/.
Disaster Preparedness for Radiological Professionals. 2002. American College of Radiology. Washington DC. A copy can be obtained from http://www.arc.org/.
Submitted by Anonymous (not verified) on Sun, 2011-04-24 12:30.
Gamma rays are electromagnetic waves produced by spontaneous decay of radioactive elements during de-excitation of an atomic nucleus. Sunlight also consists of electromagnetic waves, but gamma rays have a shorter wavelength and much higher energy. High-energy gamma rays, such as those produced by decay of cesium-137, may penetrate deeply into the body and affect cells. Gamma rays from a cobalt-60 source are often used for cancer radiotherapy.
Cesium is man made
Dose, Rem Effects
5
No observable effects
10
Difficult to demonstrate a higher incidence in fetal abnormalities or cancer effects below 10 rem dose. A 10 rem dose results in a 0.8% lifetime increase in developing cancer.
15
Threshold, blood and sperm abnormalities seen
25
Threshold, genetic effects demonstrated
70
A decrease in lymphocytes in peripheral blood chemistry profile after 24 hours indicating some bone marrow depression.
100
Hospitalization recommended
100
Acute symptoms include nausea, malaise, vomiting, and anorexia. Long term effects include a 5% cancer increase death risk, 1% genetic risk defects. The onset of acute symptoms vary with the individual but could be a few days at the low end of the dose (100 rem) or maybe an hour for doses above 200 rem. Most patients are without symptoms below 100 rem.
120
Abrupt decreases in sperm count, but recovery of natural fertility usually occurs after several months or a year
200
Bone marrow depression symptoms apparent. The onset of symptoms associated with bone marrow depression can vary with the individual and dose; but can be several weeks or even months after radiation exposure. These symptoms may occur weeks after the person has recovered from the initial onset of nausea and anorexia. Changes in the peripheral blood profile may occur as early as 24 hours after radiation exposure. Lymphocytes will be depressed most rapidly, and other leukocytes and thrombocytes will be depressed less rapidly. A 50% drop in lymphocytes in 24 hours indicates significant radiation injury. Symptoms include bleeding (hemorrhage) and anemia, diarrhea, fluid loss, and decreased resistance to infection, which become apparent several weeks after radiation exposure. Minimal treatment includes fluid replacement, antibiotics, and prevention of infection. More aggressive treatment includes bone marrow resuscitation therapy.
250
10% of people develop cataracts within several months
300
Epilation (hair loss)
350
Median lethal dose of radiation that will kill 50% of the exposed persons within 60 days without appropriate medical treatment. Mortality is low with aggressive therapy.
400
Continued loss of epithelial cells of the intestinal mucosa results in hemorrhage and marked fluid loss contributing to shock; these symptoms occur within 1 or 2 weeks after irradiation.
600
Almost 100% fatal within 60 days if untreated. Erythema occurs. Lymphocyte count decreases from normal level of about 2000 or 2500 to about 500 in 24 hours. Cognitive impairment.
800+
Rapid incapacitation. Symptoms may occur within an hour after exposure. Diarrhea, fever, electrolyte imbalance. Mortality rate high even with treatment.
2000
Onset of symptoms within minutes. Neurovascular symptoms occur within several hours to about 3 days after exposure. These include a steady deteriorating state of conscience with eventual coma and death.
The above table was constructed from the following two documents:
Medical Management of Radiological Casualties, 2nd edition, April 2003. Armed Forces Radiobiology Research Institute, Bethesda MD. A copy may be obtained from http://www.afrri.usuhs.mil/.
Disaster Preparedness for Radiological Professionals. 2002. American College of Radiology. Washington DC. See http://www.arc.org/.
Example: Cesium 137 in the PEAC tool
Let’s pull up Cesium 137 in the PEAC tool. Its chemical formula abbreviation is Cs 137. This is a man-made element which has been detected at nuclear power plants. Industrial uses include food irradiation, soil density testing, and radiography. The atomic number 137 means that the total number of protons plus neutrons is 137. The atomic weight is 136.907. Protons and neutrons do not have exactly the same mass so when the atomic weight is calculated, the number totals to 136.907 rather than an even 137.
Cesium 137 is radioactive. It emits a beta particle with maximum of 1.176 MeV (1.176 million electron volts per beta particle) kinetic energy. Accompanying this emission is 0.66164 MeV of gamma radiation. There is no alpha particle emission.
The activity of Cerium 137 is 86.6912 curies per gram. Radiation activity is usually measured in curies or microcuries [106 microcuries = 1 curie]. Activity is directly related to the number of disintegrations per unit time. One disintegration per second = 2.703 x 10-11 curies. [One disintegration per second = 2.703 x 10-5 microcuries]. Disintegration means that the cesium 137 has emitted a beta particle forming Barium 137. Barium 137 is stable and not radioactive.
The half-life of cesium 137 is 30.2 years. This means that after 30.2 years, half of the cesium 137 will have disintegrated forming barium 137. The half-life can be calculated directly knowing the activity and atomic weight.
MeV (million electron volts per particle or gamma emission) is a unit of energy. 1 MeV = 1.603 x 10-13 joules.
The relationship between MeV of energy and rem of radiation exposure is not easy to predict. Let us look at two cases, one in which the radioactive isotope is taken internally (by inhalation or ingestion) and the other case where the isotope is external to the body, but the person receives a radiation dose from the beta particles and gamma radiation.
Radioactive isotope inhaled or ingested: The U.S. Nuclear Regulatory Commission has codified the maximum annual exposure to radiation workers and general public from inhalation and ingestion of radioactive isotopes. This is in Title 10 of the Code of Federal Regulations, Part 20 Appendix B and is repeated in the PEAC tool. The worker exposure limit listed in 10 CFR part 20 is based on 5 rem/year, and the general public exposure limit is based on 0.1 rem/year.
Radioactive isotope external to human body: The degree of penetration of beta particles into the human body from the isotope depends on the distance the particle travels and its kinetic energy. A beta particle of 1.176 MeV kinetic energy can travel slightly over 1 meter in air or several centimeters in water (or several centimeters into human flesh). Clinically, beta particles produce a burn indistinguishable from a thermal burn. Gamma radiation on the other hand is much more penetrating and can produce symptoms like that listed in table 1. Neither gamma radiation nor beta particles from an external source leave residual radiation in the body.
From 10 CFR part 20, the annual limit on intake (ALI) of Cesium 137 into the body corresponding to a 5 rem dose is 200 microcuries per year. The ALI takes into account exposure to any daughter isotopes produced in the body (some radioactive isotopes have radioactive daughter species). From the ALI value, the derived air concentration (DAC) for inhalation is computed assuming a worker exposure of 2000 hours per year and a breathing rate of 20 liters per minute. The general public is based on a 0.1 rem annual exposure limit, 24 hours per day and 365 days per year. The drinking water limit is based on 730 liters intake per year.
Annual Limit on Intake of Cesium 137 for 5 rem dose: 200 microcuries
Max. Occupational Derived Air Concentration, 5 rem dose/year: 6 x 10-8 microcuries/ml
Max Public Air Concentration, 0.1 rem dose/year: 2 x 10-9 microcuries/ml
Max Public Water Concentration, 0.1 rem dose/year: 2 x 10-5 microcuries/ml.
If there is more than one radioactive isotope in the air or water, all isotopes must be considered as contributing to the radiation dose.
The external radiation exposure calculation is a little complicated. The dose depends upon whether the cesium 137 comes from a point source some distance away from the emergency responder, is uniformly distributed in the air (the responder is assumed to have an air pack), or is distributed as dust on the responder’s protective suit. For example, let us calculate the radiation dose received by a person located one meter away from one gram of cesium 137. The first step is to calculate a flux (units: gamma photon radiation/sq. meter-second) at a distance one meter from the source. Then the flux is converted to a dose rate (units: rem/hour) using lookup tables that are located in the following reference source:
“Neutron and Gamma-Ray Flux-to-Dose Rate Factors”, American National Standard, ANIS/ANS-6.11. 1977.
Other reference sources are available; this is not the only one. The flux itself is computed using a formula which has constants pulled from lookup tables. The calculations are too complicated to walk through and explain in this write-up but when we are done, the flux at one meter away is computed to be 2.6 x (10)11 gamma photons/m2-s, and the radiation dose rate is 38 rem/hour. A person one meter away might receive 114 rem dose after 3 hours. This is enough to manifest itself with clinical symptoms (nausea, may appear several days later), a decrease in blood lymphocytes (see table 1), and increased cancer risk later in life.
The gamma radiation flux (and the dose rate) falls off as the inverse square of the distance from the source. This means that if the 1-gram gamma radiation source were located 10 meters away, the dose rate would be only 0.4 rem/hour. On the other hand, if a person were dressed in a Level A protection suit and the suit becomes covered with cesium 137 dust, the dose rate can be very high. Additional Reading
Medical Management of Radiological Casualties, 2nd edition, April 2003. Armed Forces Radiobiology Research Institute, Bethesda MD. A copy may be obtained from http://www.afrri.usuhs.mil/.
Disaster Preparedness for Radiological Professionals. 2002. American College of Radiology. Washington DC. A copy can be obtained from http://www.arc.org/.
http://www.aristatek.com/drjisotopes.aspx.
Cesium is manmade
Max Public Air
Max Public Air Concentration, 0.1 rem dose/year: 2 x 10-9 microcuries/ml
Max Public Water Concentration, 0.1 rem dose/year: 2 x 10-5 microcuries/ml.
My ? Is how close our we to receiving this max dosage please respond .
Cesium
Gamma rays are electromagnetic waves produced by spontaneous decay of radioactive elements during de-excitation of an atomic nucleus. Sunlight also consists of electromagnetic waves, but gamma rays have a shorter wavelength and much higher energy. High-energy gamma rays, such as those produced by decay of cesium-137, may penetrate deeply into the body and affect cells. Gamma rays from a cobalt-60 source are often used for cancer radiotherapy.
https://marshallislands.llnl.gov/glossary.php
Cesium 137
http://www.epa.gov/radiation/docs/402-f-06-061.pdf.
See page 6 On gamma the hazards are to entire body this includes man made cesium 137