saa Joseph J. DiNunno ae” -2- "One can calculate that if the environment is sufficiently contaminated with radioiodine to deposit a constant level of 1 picocurie per gram in cattle thyroids, then human beings will be exposed, in a lifetime, to about .2 rads of radiation-- about 1/50th of the present FRC guide level. . ." Since 1 picocurie of iodine-131 per gram of thyroid tissue will produce about 0.011 millirads per day, it would take about 50 years to accumulate 0.2 rads. However, Dr. Commoner's statement is in reference to cattle thyroids and it has been shown that human thyroids contain very much less radioiodine than cattle, on a gram per gram basis. Dr. Commoner's reference to 1/50th of the FRC guide level suggests that he believes that 10 rads are the appropriate FRC guide. In fact, the FRC guide for normal peacetime operations is 1.5 rads per year for an individual in the general population. There is another subtle, but real point not always appreciated. If one is talking about a more or less continuous contamination of the environment (which was Dr. Commoner's thesis) and the dose to the thyroid of an individual infant in the population kept at 1.5 rem per year, then a man who is conceived, born and lives his full life span in such an environment would receive about 15 rem, not 105 rem (1.5 rem per year x 70 years) to his thyroid. This is due to the fact that one's thyroid increases in size from infancy to adulthood, yet the assumed daily radioiodine intake remains constant. It is also noted on page 13 of Dr. Commoner's paper he speaks of " . . . will pay that price with their lives." Disorders or even malignancies of the thyroid are not fatal. If other actions cannot alleviate the symptoms, then surgery may be indicated and such action has been proven successful in the Marshallese who received large radiation doses to the thyroid. On page 9 Dr. Commoner makes reference to some iodine levels in the 1959-61 period. We are obtaining a copy of the report from which Dr. Commoner drew his data and will give you our comments later. KisFuler Martin B. Biles, Director Division of Operational Safety ec: R. J. Catlin, ADHP, OS