20 miles of ground zero where there was relatively heavy local in those areas where the amount of fallout was high, i.e., poss!bly over 75 roentgens whole body dose from the gamma radia- fallout from the bursts occurring on towers. Crude estimates suggest that the external whole body exposures in these same areas would have been in excess of 75 roentgens from gamma tion with most of this exposure occurring in the first few days. Thus, the potential hazard of skin burns may be essentially eliminated by meeting the criteria of an acceptable whole body rays.!! The principal example of skin damage wasin the case of the exposure. Of course, by evacuation from a highly contaminated area it is possible to reduce drastically whole body exposure, yet a relatively high skin dose could accumulate if the fallout materials were not removed early. Marshallese people following the heavy fallout on March 1, 1954.4 The most damaged areas were (a) in the regions of hair on the head (oiled), (b) folds of the moist bare skin such as the neck region and inner elbow, and (c) tops of the feet where the fallout material remained in place (figs. 4a and 4b). The 45 individuals......... superficial lesions 13 individuals.........deep lesions 6 individuals......... no lesions Total......... 64 35 individuals (of the 64 above).........some degree of epilation Hair of normal color and texture has regrown andall lesions have healed without visible effects except for permanentloss of pigment in the healed areas in individuals and some scar tissue behind the ear of one man, marking the location of a previous deep lesion. Additional cases of skin damage from fallout were observed on some Japanese fishermen aboard the Fukuryu Maru and some American service personnel on the island of Also, four The damaged area showed normalrepair processes but the pre- viously black hair of the eyebrow was replaced by white hair upon regrowth.” There have been no known cases of human beta burnsat or around the Nevada TestSite. Evaluation Serious skin damage can result if highly radioactive fallout remainsin direct contact with the skin. Simple measures such as washing can be very effective in reducing this hazard —the sooner the better. 10 Skin damage has not been observed except Background Information Approximately 0.15 million curie (a “curie’’ corresponds to 2.2 million million disintegrations of nuclei per minute) of iodine 131 are produced for each kiloton TNT equivalent of energy released by fission. For large yield airbursts most of the iodine 131 along with other radioactive materials will be swept into the upper atmosphere (stratosphere) and, since iodine 131 has a half-life of only eight days, a large part of its activity will decay before being deposited on the earth. On the other hand, iodine 131 that remains in the lower atmosphere, the . troposphere, will be deposited relatively quickly and can enter the food chain. Milk is the principal route of entry of iodine 131 into the human body whereit is selectively deposited in the thyroid gland. The assumption is usually made that 30 percent of iodine 131 ingested by humans is deposited in the thyroid no matter what the size of this organ may be." Thus, an infant’s thyroid gland of about two grams weight would receive 10 times more radiation dose than the 20 gram adult’s thyroid for the same amount of iodine 131 ingested. For this reason calculations of radiation doses from iodine 131 for the general ee men in charge of handling “hot” filters from monitoring aircraft at the Pacific Testing Site in 1948 received severe beta burns on the hands. One additional case was an Air Force officer in charge of transportation of radioactive samples from the Pacific Proving Ground to the United States in 1951. A lesion developed on his forehead and right eyebrow region. ne ee Rongerik, as a result of the March 1, 1954 fallout. D. IODINE 131 ee extent of skin damageto the most heavily exposed group may be summarized asfollows. population are based on those for the infant rather than the adult. Direct measurements of iodine 131 in milk were not made around the Nevada Test Site during earlier times of testing since it was the consensusof scientists within and outside the AEC and Governmentat that time that the limiting factor was the potential external whole body exposure. It is now recog- nized that there can be situations where the iodine 131 exposure can be more limiting. An example of this was the Smallboy surface shot on July 14, 1962 at the Nevada Test Site. The detonation was large enough to produce significant quantities of iodine 131 but dueto its low energy yield the activity was not swept to high altitudes to be carried away, 745-413 O-64—3 11