Radioactivity It won’t make you glow in the dark but there are a lot of things it will do.

Learning Objectives Describe the source and types of nuclear radiation. Describe the characteristics of atoms that produce nuclear radiation. Compare the characteristics of the 4 major types of radiation. Describe the effects of radiation exposure.

Sources of Radioactivity Radioactivity is produced whenever unstable (radioactive) isotopes shed nuclear particles in an effort to gain stability. –Not all atoms are unstable. –Most elements have at least one unstable form (isotope) –In some elements, all of the naturally occurring isotopes are radioactive –Generally unstable isotopes have either too many or too few neutrons in their nucleus –Different nuclear particles can be thrown out of the nucleus in order for an atom to regain stability, depending on whether the atom has too many or too few neutrons (Decay Reactions).

Types of Nuclear Radiation Alpha - Made up of 2 protons and 2 neutrons (Helium nucleus) –Emitted by large, slightly unstable atoms –Slow speed and low penetrating ability –Strong ionizers, can do serious damage to living cells Beta - High energy electron (-) or positron (+) –Emitted by small atoms with an excess (-) or lack (+) of neutrons –High speed, high energy, moderately penetrating particle –Moderate ionizers, damage is much less severe than alpha particles Gamma - Extremely high energy light rays –Emitted by all unstable atoms –High energy, high penetration –Weak ionizers compared to alpha and beta particles Neutron - High energy neutron particle –Emitted by large atoms undergoing fission –High penetrating power, very weak ionizers

Radiation Characteristics Relative Penetrating Strength –Alpha - Cannot penetrate skin or clothing –Beta - Can penetrate light clothing and top layers of skin –Gamma - Penetrate through body, 1” steel, 2’ concrete –Neutron - Penetrate into or through body, 1” steel, 2’ concrete Relative Danger to Living Cells –Alpha - Extremely hazardous to soft tissue (lungs) in small amounts Common hazard in cigarette smoke, most common cause of lung cancer –Beta - Hazardous to unprotected cells with moderate exposure –Gamma – Very hazardous to living cells in moderate to high levels –Neutron - Hazardous only at very high levels. –The hazardous effects of all radiation are cumulative. That means the more exposure to ionizing radiation you experience over time, the more likely you are to suffer the effects (cancer, leukemia, anemia and radiation poisoning)

Sources of Radiation Exposure Alpha –Nuclear fallout –Cigarette or other types of smoke –Background radiation Beta –Nuclear fallout –Background radiation Gamma –Sunlight, greater at higher altitudes –Nuclear fallout –Background radiation Neutron –Nuclear power plants –Nuclear Waste

Annual Radiation Exposure by Source Recommended Maximum Exposure <1000

Radiation Effects on Humans Acute Exposure – High levels of radiation over a short period of time –Radiation sickness – Digestion system failure, anemia, severe burns Death in 2-4 days Ingesting Radioactive Materials – Radioactive material in the lungs or intestines is localized in body parts (most common) –Constant exposure to soft tissues causes destruction of surrounding tissue and cancer formation –Radioactive iodine affects thyroid gland –Radioactive strontium affects bones –Radon attacks lungs Accumulated Exposure – Exposure to radiation from several different sources causes accumulated damage –The higher the accumulated exposure, the greater the magnitude and likelihood of damage –The most common result of accumulated damage is cancer and birth defects (changes to cellular DNA)

Key Concept Review Radiation is released from unstable atomic nuclei Alpha radiation has the most devastating effect on soft tissues, but is unable to penetrate skin or clothing Beta radiation is weaker at damaging cells than alpha radiation, but much more penetrating going through clothing and several layers of skin Gamma radiation is the least damaging but highest penetrating, able to penetrate the entire body, 2 feet of concrete and an inch of steel Neutron radiation has variable penetration and low ionization energy There are multiple sources of radiation exposure Radiation exposure can be acute or chronic and results in several related conditions such as cancer, radiation poisoning and birth defects