RADIATION STANDARDS, INCLUDING FALLOUT 3 STATEMENT OF G. HOYT WHIPPLE,' PROFESSOR OF RADIOLOGICAL HEALTH, SCHOOL OF PUBLIC HEALTH, UNIVERSITY OF MICHIGAN Dr. Wurprie. Mr. Price, it is a pleasure for me to appear before you again in the role of a college professor. Of the many topics you will consider, the one assigned to meis perhaps the only one where opinion and subjective judgment play no part. In sayingthis I do not wish to give the impression that college people have no opinions, or do not indulge in subjective judgment; we are as competent in these regards as most, but my assignment precludes these liberties today. In the belief that greater clarity will result, I have inverted the order of the subjects in the schedule for the proposed hearings. I shall speak first of the types of radiation, then of the units of measurement, and finally of the sources of human exposure. Types of radiation and their definition: For the present purposes of this subcommittee only four types of ionizing radiation need be discussed : alpha particles, beta particles, gamma rays, and X-rays. The table included with this statement summarizes some of the characteristics of these radiations, (The table referred to follows:) Characteristics of the principal types of radiations Characteristic a particles 8 particles rays Sources._.....2--.-..-22 e-emitting radio§-emitting radioMany femitting active isotopes, active isotopes, tadioactive isoe.g. Pus?, e.g, Sr, topes, o.g. Cos”. Mass..-.-.-..--------.. 1/1800 a.m.ut_.__} OL Electrical charge._..... + —le 7. ieee OL. eee Velocity (in miles per 175,000 (1 mev 4)_._] 186,000 (all enersecond). gies). Typleal energies (in 4 to 8... O.1 to 2.222222. 0.1 te 62222 mev 3), Typical ranges: 5 mev: 1 mev: In air... ee. 1.4 inches. .__. 10,5 feet___._..j)--------..-~---.---In tissue_____...__0.0014 inch.___ 0.16 Inch... 2)..-----.------- ee Half-value layer: ¢ I mev: In tissue__......._./ 2-2-2.) eee 4inches....... In lead___.-2 oe) eee ee ee ee 0.3 inch....._' 2? 3 4 X-rays X-ray machines. 0. Q. 186,000 (all energies). 0.01 to 1, 0.1 mev: 1.6 inches. 0,004 inch, A,m,u, is atomic mass unit and equals 1.7 x 10-4 gram. eis the charge on the electron, Mevis million electron volts and equals 1,6 x 10-8 ergs, oo. The half-value layer is that thickness which reduces the intensity of the radiation to half its initial value. Dr. Wurertr. (a2) Alpha particles: Alpha particles, as a result of their relatively large mass and of their double electric charge, lose energy rapidly in passing through matter and as a consequence go only very short distances. To illustrate: a 5-million electron volt alpha particle has a velocity of about 10,000 miles per second and is stopped completely by an inch or twoof atr, or by 1 or 2 mills of living 19 eeraPhical data: Name: Whipple, G. Hoyt. é Born: San Francisco, Calif., May 4, Edueation: Public schools: Rochester, New York. College: 1. Wesleyan University, 1935-39, B.S. in chemistry; 2. Massachusetts Institute of Technology Graduate School, 338te, no degree; 3. University of Rochester Graduate School, 1950-53, Ph. D. in iophysics. Experience: MIT Division of Industrial Cooperation: 1942-47. Loran, radar, food dehydration, aerial bomb fuses, ete.. Government-sponsoder research. General Blectric Co.. Hanford works, Richland, Wash.: 1947-50. Research and development on health physics problems and instruments. University of Rochester atomic energy project: 1950-— 57. Teaching in health physics and research in biophysics. The University of Michigan School of Public Health, Ann Arbor, Mich.: September 1957 to present. Teaching and research ; professor of radiological health. sanaCSNanaenaeebatinitineNatta