munity was about 6 roentgens. There were about 30 persons who received exposures between 6 and 10.5 roentgens. All of the above radiation doses are accumulated doses since the Nevada Test Site opened in 1951.9 Having delineated these highest exposures it is proper to discuss “average” exposures since these have relevance for evaluating possible genetic effects. The average whole body exposure to persons in the United States (to be accumulated over 30 years) from all past nuclear detonation tests of United States, United Kingdom and U.S.S.R. (the French tests contributed very little) has been estimated to be 110 milliroentgens* (0.11 roentgens).! Somewhat over one-half of this exposure will result from radioactive fallout materials outside the body. The remainder is due to carbon 14 and cesium 137 deposited internally following ingestion (inhalation contributes negligible amounts). In the case of the Eskimos, the highest measured amount of HOLMES AND NARVER PHOTO FIGURE 3.—Rongelapese returned to their home island June 1957. were newly built by the U.S. Government. Structures itching of the skin (see section on Skin Exposure below, section I C page 8). Also, there were definite changes in levels of blood consti- tuents for months afterwards. The Marshallese have been ex- amined by a team of physicians yearly and to the present time no statistical differences have appeared between them and the “control” group for such factors as birth and death rates, life- shortening, leukemia, cataracts or cardiovascular, arthritic, ophthalmic, or dental defects. There may be a suggestion of greater incidence of miscarriages and stillbirths and more recent data indicate that there may be a lag in growth and development of the children, but the paucity of vital statistics and the small number of persons involved preclude a determinnation. It was reported by the Japanese that some fishermen aboard a vessel nearthe Pacific Proving Ground on the same date may have received a higher exposure than the Marshallese.? One of these fishermen died on September 23, 1954 of a liver disorder complicated by the development of jaundice and pneumonia.® The highest estimated exposure to any individual near the Nevada Test Site was 13.5 roentgens and the next highest 10.5 roentgens. The highest estimated exposure to any com6 externally deposited cesium 137 in any individual was in June 1963.'"° This highest quantity of cesium 137 would produce a dose rate of about 190 milliroentgens (0.19 roentgen) per year at the time of measurement. The highest average for any group (Anaktwvuk Pass, Alaska) was about one-half of this value. Since cesium 137 contamination of the lichens is a surface phenomenon-very little is taken up from the soil— and the normal biological time to remove half of any remaining cesium activity in the body is only about 100 daysor possibly less, the annual dose should dropoff in 1964-65. Evaluation A whole body exposure of 175 roentgens (Marshallese experience in 1954) is far in excess of an acceptable exposure. As contrasted with the surface bursts in 1954, the 1962 U.S. tests in the Pacific were bursts in the air high enough above the surface to eliminate measurable local fallout. Only a few individuals have exceeded by small amounts the criterion of 10 roentgens in 10 years established for the Nevada Test Site. The whole body average population 30 year exposure of 110 milliroentgens (0.11 roentgen) is about three percent of that from natural sources. The difference in natural background radiation levels at various localities in the United States can be much greater than all of the whole body exposure from fallout. *A milliroentgen is 1/1000 of a roentgen.