me te ae en ee I re, important mode of entry of radioiodines in fallout, In sources of drinking water for major urban populations the delay between rainfall and consumption usually assures decay of iodine-131 to an insignificant level. In addition dilution and other factors are effective in reducing the fallout concentration, Fresh food becomes, then, the main source of iodine-131 from the environment. For most foods the time delay between harvest and consumption is sufficient to reduce iodine-131 to an insignificant level. This is not generally the case with fresh milk for which the time between production and consumption averages about 3 days in the United States. There is some evidence suggesting that consumption of some locally grown vegetables and produce, even after washing and normal home preparation, could conceiyably contribute to the diet amounts of the order of those from fresh milk. However, there is no question but that fresh milk is by far the major contributor of iodine-131 to the United States population as a whole. Relatively little information is available on the consumption of fresh cow's milk by people in various age groups. The most detailed study now available was completed in 1962 and presents per capita consumption by age and sex.499 During the first few months of life, the intake of fresh cow's milk may be zero for infants who are breast-fed or given formulas based on processed products. From the survey study, the average for children under one year of age was about 0.5 liter per day which was maintained until late in teenage after which a gradual decline occurred. For adult males and females in the population-at-large averages were 0.35 and 0.25 liters per day respectively. The range extended from persons consuming no milk to a group comprising 1 to 10 percent who consumed more than 1 liter per day. Large individual differences were found at all ages. The thyroid gland is unique in its relation to the metabolism of todine in either stable or radioactive form. Weighing only about 1 to 2 grams at birth, and 15 to 20 grams in the adult, this gland has a high affinity for iodine. A normal thyroid will absorb and retain 15 to 30 percent of a small quantity of ingested iodine, The exact amount retained will depend, among other things, upon the amount of stable iodine ingested during the 3R, H. Wasserman, F. W. Lengemann, J. C. Thompson, Jr., and C. L. Comar. "The Transfer of Fallout Radionuclides from Diet to Man," Chapter 9, in Radioactive Fallout, Soils, Plants, Foods, Man edited by E. B. Fowler, Elsevier, 1965. in 4Rureau of the Census, Department of Commerce and Division of Radiological Health, Public Health Service, "National Food Consumption Survey: Fresh Whole Milk Consumption in the United States." Radiological Health Data 4:15, No. 1, 1963, Bureau of the Census, Department of Commerce and Division of Radiological Health, Public Health Service, "Consumption of Selected Food Items in 'U. S. Households."' Radiological Health Data 4:124, No. 3, 1963. POE ARCHIVES