PET ageadysn TESS By GS OSSe REE EOheeagags SOE RADIATION STANDARDS, INCLUDING FALLOUT 111 There are other small differences that result from the standardization of the milk. Senator Arxen. In each case is the sample taken from homogenized milk? Dr. Cuapwicx. I really can’t answer that question, sir. I would assumeit is, since I assume that most of the milk sold now is homogenized. This is processed milk. That is, after the completion of the process. So I would certainly assume that it is homogenized. Senator Arken. Would you say that the higher the butterfat con- tent the lower the probable amount of radioactive material would be? Dr. Cuapwicx. I would doubt, sir, if there would be any consistent relationship between butterfat content and radioactivity. Representative Price. Will you proceed, Dr. Chadwick ? Dr. Cuapwick. The results of the milk monitoring network have been published regularly in Radiological Health Data since it was first published in April 1960. The data prior to 1959 were presented to this committee during the fallout hearings in 1959. All of the data since 1959 have been summarized in two reports which I would like to submit for the record. These are “Intake of Iodine 131 by U.S. Population, Fall of 1961,” and “The Intake of Strontium 90 and Certain Other Radionuclides by the U.S. Population.’ I should like to summarize these reports. Representative Price. They will be received. (Documentsreferred to follow :) INTAKE OF IopINE 131 By U.S. PopuLaTIoN, FA or 1961 BACKGROUND It was not generally appreciated iodine 131 released by nuclear fission would appear in the thyroids of livestock until 1954 when data were published by Van Middlesworth (1) that iodine 131 from 1958 atomic test series had appeared in thyroid glands of cattle. This work was confirmed by other investigators, references 2 to 5. Wolff (6) suggested that milk might be a major vector in the transmittal of iodine 131 to the human population. This has since been confirmed by the Public Health Service milk-sampling program. Van Middlesworth (7) reported human thyroid glands from autopsies in Memphis, Tenn., examined for radioiodine from November 1954 through August 1955. There were 175 glands and the iodine 131 content varied from 1 to 100 wzyc/g thyroid tissue. In the 1959 hearings on fallout from nuclear weaponstests attention was drawn to radioactive iodine as a possible significant factor in human radiation exposure. Dr. E. B. Lewis, in a statement prepared for the record, said that from “data supplied by Campbell et al. (8) on the amount of Iin fresh cow’s milk during a 16-month period between June 1957 and ending September 1958 it can be estiinated that the thyroid glands of the average infant and young child in the United States have received doses of beta radiation from I™ that amount to roughly 0.1 rad to 0.2 rad per year. There is some reason to believe that such doses have been delivered annually over the past + to 5 years of weapons testing.” PUBLIC HEALTH SERVICE MILK MONITORING When the Public Health Service in 1957 undertook to assess the amounts of radioactive fission products being ingested by the population of the United States, milk was selected as the first item to be surveyed. This was a logical choice for the following reasons: 1. Milk is a major element of the diet of infants and children. 2. Milk is a food used extensively by all segments of the population. 3. The biochemistry of milk production is sueh that it would be expected fer ain some of the most important radioisotopes that might enter the otal diet. poetsRRRRRPPRTEDERpintrietiectapestsedSAY “Hbolit-Hicscpepnicheipsgsahara: