understanding_radiation

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Understanding Radiation and Its Effects:

1/17/2013 *UCRL-PRES-149818. This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48. 1 Understanding Radiation and Its Effects Prepared by Brooke Buddemeier, CHP LLNL Counter Terrorism and Incident Response Program Lawrence Livermore National Laboratory* [email protected] (925) 423-2627 UCRL-PRES-149818-REV-2

Radiation is Energy:

1/17/2013 UCRL-PRES-149818. Understanding Radiation and it’s Effects. 2 Radiation is Energy The energy is given off by unstable (radioactive) atoms and some machines. For this talk, we will be focusing on ionizing radiation and its health effects.

Radiation and Radioactive Material are a Natural Part of Our Lives:

1/17/2013 UCRL-PRES-149818. Understanding Radiation and it’s Effects. 3 Radiation and Radioactive Material are a Natural Part of Our Lives We are constantly exposed to low levels of radiation from outer space, earth, and the healing arts. Low levels of naturally occurring radioactive material are in our environment, the food we eat, and in many consumer products. Some consumer products also contain small amounts of man-made radioactive material. Smoke Detector

Unstable Atoms Decay:

1/17/2013 UCRL-PRES-149818. Understanding Radiation and it’s Effects. 4 Unstable Atoms Decay The number of “decays” that occur per unit time in the radioactive material tell us how radioactive it is. Units include Curies (Ci), decays per minute (dpm), and Becquerels (decays per second). When an unstable atom decays, it transforms into another atom and releases its excess energy in the form of radiation. Sometimes the new atom is also unstable, creating a “decay chain”

Forms of Radiation:

1/17/2013 UCRL-PRES-149818. Understanding Radiation and it’s Effects. 5 Forms of Radiation When unstable atoms transform, they often eject particles from their nucleus. The most common of these are: Alpha Radiation High energy, but short range (travels an inch in air, not an external hazard) Beta Radiation Longer range (10 – 20 feet in air) and can be a skin and eye hazard for high activity beta sources. Gamma Rays (electromagnetic radiation) Often accompany particle radiation. This “penetrating” radiation is an external hazard and can travel 100s of feet in air. gamma gamma

How Unstable Is It?:

1/17/2013 UCRL-PRES-149818. Understanding Radiation and it’s Effects. 6 How Unstable Is It? The “Half-Life” describes how quickly Radioactive Material decays away with time. It is the time required for half of the unstable atoms to decay. Some Examples: Some natural isotopes (like uranium and thorium) have half-lives that are billions of years, Most medical isotopes (like Technicium-99m ) last only a few days

Some Isotopes & Their Half Lives:

1/17/2013 UCRL-PRES-149818. Understanding Radiation and it’s Effects. 7 Some Isotopes & Their Half Lives ISOTOPE HALF- LIFE APPLICATIONS Uranium billions of years Natural uranium is comprised of several different isotopes. When enriched in the isotope of U-235, it’s used to power nuclear reactor or nuclear weapons. Carbon-14 5730 y Found in nature from cosmic interactions, used to “carbon date” items and as radiolabel for detection of tumors. Cesium-137 30.2 y Blood irradiators, tumor treatment through external exposure. Also used for industrial radiography. Hydrogen-3 12.3 y Labeling biological tracers. Irridium-192 74 d Implants or "seeds" for treatment of cancer. Also used for industrial radiography. Molybdenum-99 66 h Parent for Tc-99m generator. Technicium-99m 6 h Brain, heart, liver ( gastoenterology ), lungs, bones, thyroid, and kidney imaging, regional cerebral blood flow, etc.

The Amount of Radioactivity is NOT Necessarily Related to Size:

1/17/2013 UCRL-PRES-149818. Understanding Radiation and it’s Effects. 8 The Amount of Radioactivity is NOT Necessarily Related to Size Specific activity is the amount of radioactivity found in a gram of material. Radioactive material with long half-lives have low specific activity . 1 gram of Cobalt-60 has the same activity as 1800 tons of natural Uranium

What is a “Dose” of Radiation?:

1/17/2013 UCRL-PRES-149818. Understanding Radiation and it’s Effects. 9 What is a “Dose” of Radiation? When radiation’s energy is deposited into our body’s tissues, that is a dose of radiation. The more energy deposited into the body, the higher the dose. Rem is a unit of measure for radiation dose. Small doses expressed in mrem = 1/1000 rem . Rad & R (Roentgens) are similar units that are often equated to the Rem.

Typical Doses:

1/17/2013 UCRL-PRES-149818. Understanding Radiation and it’s Effects. 10 Typical Doses Average Dose to US Public from All sources 360 mrem/year Average Dose to US Public From Natural Sources 300 mrem/year Average Dose to US Public From Medical Uses 53 mrem/year Coal Burning Power Plant 0.2 mrem/year Average dose to US Public from Weapons Fallout < 1 mrem/year Average Dose to US Public From Nuclear Power < 0.1 mrem/year Occupational Dose Limit for Radiation Workers 5,000 mrem/yr Coast to coast Airplane roundtrip 5 mrem Chest X ray 8 mrem Dental X ray 10 mrem Head/neck X ray 20 mrem Shoe Fitting Fluoroscope (not in use now) 170 mrem CT (head and body) 1,100 mrem Therapeutic thyroid treatment (dose to the whole body) 7,000 mrem

Radiation is a type of energy; Contamination is material:

1/17/2013 UCRL-PRES-149818. Understanding Radiation and it’s Effects. 11 Radiation is a type of energy; Contamination is material Exposure to Radiation will not contaminate you or make you radioactive. Contamination is Radioactive Material spilled someplace you don’t want it. Radioactive contamination emits radiation. Contact with Contamination can contaminate you with the material.

Our Bodies Are Resilient:

1/17/2013 UCRL-PRES-149818. Understanding Radiation and it’s Effects. 12 Our Bodies Are Resilient DNA damage is most important and can lead to cell malfunction or death. Our body has ~ 60 trillion cells Each cell takes “a hit” about every 10 seconds, resulting in tens of millions of DNA breaks per cell each year. BACKGROUND RADIATION causes only a very small fraction of these breaks (~ 5 DNA breaks per cell each year). Our bodies have a highly efficient DNA repair mechanisms

Types of Exposure & Health Effects:

1/17/2013 UCRL-PRES-149818. Understanding Radiation and it’s Effects. 13 Types of Exposure & Health Effects Acute Dose Large radiation dose in a short period of time Large doses may result in observable health effects Early: Nausea & vomiting Hair loss, fatigue, & medical complications Burns and wounds heal slowly Examples: medical exposures and accidental exposure to sealed sources Chronic Dose Radiation dose received over a long period of time Body more easily repairs damage from chronic doses Does not usually result in observable effects Examples: Background Radiation and Internal Deposition Inhalation

Dividing Cells are the Most Radiosensitive:

1/17/2013 UCRL-PRES-149818. Understanding Radiation and it’s Effects. 14 Dividing Cells are the Most Radiosensitive Rapidly dividing cells are more susceptible to radiation damage. Examples of radiosensitive cells are Blood forming cells The intestinal lining Hair follicles A fetus This is why the fetus has a exposure limit (over gestation period) of 500 mrem (or 1/10 th of the annual adult limit)

At HIGH Doses, We KNOW Radiation Causes Harm:

1/17/2013 UCRL-PRES-149818. Understanding Radiation and it’s Effects. 15 At HIGH Doses, We KNOW Radiation Causes Harm High Dose effects seen in: Radium dial painters Early radiologists Atomic bomb survivors Populations near Chernobyl Medical treatments Criticality Accidents In addition to radiation sickness, increased cancer rates were also evident from high level exposures.

Effects of ACUTE Exposures:

1/17/2013 UCRL-PRES-149818. Understanding Radiation and it’s Effects. 16 Effects of ACUTE Exposures Dose (Rads*) Effects 25-50 First sign of physical effects (drop in white blood cell count) 100 Threshold for vomiting (within a few hours of exposure) 320 - 360 ~ 50% die within 60 days (with minimal supportive care) 480 - 540 ~50 % die within 60 days (with supportive medical care) 1,000 ~ 100% die within 30 days * For common external exposures 1 Rad ~ 1Rem = 1,000 mrem

At LOW Doses, We PRESUME Radiation Causes Harm:

1/17/2013 UCRL-PRES-149818. Understanding Radiation and it’s Effects. 17 At LOW Doses, We PRESUME Radiation Causes Harm No physical effects have been observed Although somewhat controversial, this increased risk of cancer is presumed to be proportional to the dose (no matter how small). The Bad News: Radiation is a carcinogen and a mutagen The Good News: Radiation is a very weak carcinogen and mutagen! * Similar to those received by Atomic Bomb Survivors (≥10 rem)

Long-term Effects of Radiation:

1/17/2013 UCRL-PRES-149818. Understanding Radiation and it’s Effects. 18 Long-term Effects of Radiation Radiation is assumed to increase one’s risk of cancer The “normal” chance of dying of cancer is ~ 23% (~460 out of 2,000). Each rem is assumed to increase that risk by 0.05% (~1 chance in 2,000). The occupational radiation dose limit to the whole body is 5 rem/yr

Conclusion (1 of 2): Understanding Radiation and it’s Effects:

1/17/2013 UCRL-PRES-149818. Understanding Radiation and it’s Effects. 19 Conclusion (1 of 2): Understanding Radiation and it’s Effects Radiation is energy given off by unstable atoms and some machines. Radioactive Material contains unstable atoms that give off radiation when they “decay.” Contamination is Radioactive Material spread someplace where you don’t want it.

Conclusion (2 of 2): Understanding Radiation and it’s Effects:

1/17/2013 UCRL-PRES-149818. Understanding Radiation and it’s Effects. 20 Conclusion (2 of 2): Understanding Radiation and it’s Effects Radiation damages our cell’s DNA, fortunately our body has very efficient repair mechanisms. Large acute doses of radiation can cause sickness or even death. The severity of the effects are proportional to the dose. All exposures to presumed to increase the risk of cancer. The amount of “increased risk” is proportional to exposure. Very Small DOSE = Very Small RISK

References:

1/17/2013 UCRL-PRES-149818. Understanding Radiation and it’s Effects. 21 References Risk, DNA, & Dose Effects: RadEFX(sm) Ionizing Radiation Health Effects Forum Copyright © 1994-1997 Baylor College of Medicine, All rights reserved. http://radefx.bcm.tmc.edu/ionizing/subject/risk/acute.htm Which cites several references, including: NCRP Report 98 "Guidance on Radiation Received in Space Activities," NCRP, Bethesda (MD) (1989). Health Effects Model for Nuclear Power Plant Accidence Consequence Analysis. Part 2, Scientific Basis for Health Effects Models. U.S. Nuclear Regulatory Commission, Report NUREG CR-4214, Rev. 1. Part II. Washington, D.C. NRC: 1989 Smithsonian, V26 No.9. December 1995; “RISK, Part 2: Safeguarding our cells” by James Trefil. Other Graphics and Info from: Uranium Information Centre Melbourne, Australia http://www.uic.com.au/index.htm DOE; Transportation Emergency Preparedness Program (TEPP) http://www.em.doe.gov/otem/program.html