oo 4.13.8 Conclusions . “ . 1. Consideration of the degree of depression of peripheral cellular elements indicates that exposure of these Rongelap people was moderately severe, probably within 50 and at most 100 roof the level where some fatalities would have resulted. 2. The degree of effect evidenced in the Rongelap people is not inconsistent with the physical estimates of gamma dose received. Beta lesions of the skin, and the low levels of internal radioactive contamination observed are considered not to have contributed significantly to the hematological chanpres seen. 3. The extensive serial hematological data obtained, considered in connection wilh prea pe vious data, allow reasonably accurate characterization of the hematological respouse of hunian beings exposed to singe doses of penetrating radiation in the high sublethal range. The time course of events is different from that observed in large animals and piuryv be deseribed as follows: ay ‘The fotal white count inereases during the first (wo or more days and then decreases below normal levels. The total count then fluctuates over the next five or six weeks, wilh noe definite minimum and with some values above normal (the presence of thermal or beta lesions, or olher acute processes during (his lime may account in part for these Quctuations). The count becomes stabilized during the seventh or eighth weeks at low levels, and minimon counts probably occur at this time. A definite trend upward is apparent in the ninth or tenth -veks; b) The neutrophile count paralleis the total white blood cell count. Complete return to normal values does not occur for several months or more. The initial rise in total white count is due to a neutrophilic .. ukocytosis. c) The drop in lymphocytes is early and profound. No evidence of recovery may be apparenl several months after exposure, and return to normal levels may not occur for months or years, d) The platetet count, unlike the fluctuating total leukocyte count, falls ina regular fashion and reaches a low on the 30th day. Some recovery is evident early; however, as with the other _elements, recovery may not be complete several months after exposure. 4. As an index of severity of exposure, particularly in the sublethal r.nge, the total white or neutrophile counts are of limited usefulness because of wide Muctuations and because several weeks may be required for maximum depression to become evident. The lymphocyte count is of more vilue in this regard particularly in the low duse range, since depression occurs within hours of exposure. However, since a marked depression of lymphocyte counts oc curs with low doses and since further increase in dose produces little more depression, this index is of little value at the hixher doses. 9. Platelet counts showed a regular pattern of change in the present studies, with the same time of maximum depression in all exposure groups and with the degree of depression roughly proportional to the calculated doses. It appears, therefore, that the platelet count has considerable promise inthe sublethal range as a convenient and relatively easy direct method of determining the degree of exposure. ieee ree however, complete recovery may require several months or more. ... —_ eS : erage wee : L r enee beeeen a seeeseea sest ® ' , 88