4.13.8 Conclusions 0S sss . 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 Jatalibes would have resulted, 2. The degree of effect evidenced in the Rongelap people is not inconsistent with the physical estimiutes 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 hematolopreal chanpes seen, , 4. The extensive serral hematological data obtained, considered in connection with previous data, allow reasonably accurate characterization of the hematological response of huniain beounps exposed to sipbe doses of penetrating radiation in Che high sublethal cane. The tune course of events is different from that observed in large animals and mav be deseribed as follows: a) The total white count wrereases during the first two or more days and then decreases below normal tevels. ‘The fotal count then fluctuates over the next five or six weeks, with no definite minimum and with some values above normal (the presence of thermal or beta lestons, oroolher acute processes during this (ime may account in part for these fluctuations). The count becomes stabilized during the seventh or cighth weeks at low levels, and minimum counts probably occur at this time. A definite trend upward is apparent in the ninth or tenth weeks; however, complete recovery may require several months or more. b) The neutrophile count parallels the total white blood cell count. Complete return to normal values does not oecur for several months or more, The tnitial rise in total white count is due to a neutrophilic leukocytosis. c¢} The drop in lymphocytes is early and profound. No evidence of recovery may be apparent several months after exposure, and return to normal levels may not occur for months or years, d) The platelet 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 fluctuations and becausé several weeks may be required for maximum depression to become evident. The lymphocyte counts of more value in this regard particularly in the low dose range, since depression occurs within hours of exposure. However, since a marked depression of lymphocyte counts occurs with low doses and since further increase in dose produces little more depression, this index is of little value at the higher doses. 5. 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 in the sublethal range as a convenient and relatively easy direct method of determining the degree of exposure, o 7 see ss » Ss * se ee te ° “ . 4 . . . . . . ose oof ere oa a « . ae . ¢ #4 ee eof se + ee ° se. eee ee ee ee 8 e os ee e #8 eo} ee .e so. 4 ae 7 a ene ne