peri represent the only darge series in which systematic Serial Cadats Othe sane pndivadiuadls duiave been possible, and thus (hey comprise the most complete dati available on fumian beings ex posed an the high sublethal range. His also of dmportance, therefore, fa examine the present results dn conjunction with past expectence inn effort to gain a better understanding, of the hematological responBe of human bempgs exposed to peucteatup cadiation in the sublethal range, In the followme discussion it will be generally assumed Chat the hematological effects 4 ee ae noted were due primarily to the penetrating ganima radiation received, The beta radiation tnjury of the skin may have contributed to fluctuations in the white count during the perfod of active lesions during the third, fourth, and fifth week, but is considered not to have contributed significantly to depression of any peripheral clements (see chapter 3). The degree of internal contamination with fission products (gee chapter 5) was probably too small to contribute significantly to the carly hematological effects observed. Althoughit is not possible to say with certainty that these added factors did not materially affect the hematological pattern seen, it will become evident in the discussion that the changes observed are not inconsistent with those to be expected from exposure to penetrating radiation alone. Thus the hematological changes noted are considered to be the result of a single exposure to penetrating gamma radiation, delivered at rapidly decreasing dose rates over a period of approximately two days. Unless otherwise stated all discussion will be Umited to the adult Rongelap group. The principle sources of previous data available for comparison, and the characteristics and limitations of cach are summarized in Table 4.10. Perusal of the table will make apparent the difficulties involved in attempting strict comparisons; however, some statements can be made despite the obvious limitations, For easy reference, “normal” values for peripheral blood counts, from the present data and from the literature ure presented in Table 4.11. 4.13.2 Comparison with the Japanese Data The limitations staced in Table 4.10 apply to the Japanese low dose groups* E to H in particular, in which values given*®:*' are pooled and include individuals located at the time of the bombing such that they may not have received significant exposure. Hence, while the pattern of change with respect to time is of value, absolute counts probably are high. The time course of hematological change i: the Rongelap people corresponded most closely with these low exposure Japanese groups in which definite signs of severe radiation exposure were present in some individuals but in which essentially no mortality occurred (initial hemotological studies on the Japanese terminated at 15 weeks). The early period up to approximately six weeks was characterized by considerable variation in total white count in both the Rongelap and Japanese people. This fluctuation may be associated with the presence of thermal or other injuries in the Japanese or the active skin lesions in the Marshallese, or may correspond to the “abortive rise” poted for animals following exposure, 5! .4 From the sixth week until the termination of the acute studies on the Marshallese during the tenth week, the Japanese and Marshallese counts remained at similar levels, . The neutrophile count in both the Japanese and Marshallese in general paralleled the total white count. The lymphocyte count in both groups was depressed carly and remained depressed _ at values of approximately 2000 until week 10. The high value of 2692 reported Jor the Japanese for weeks 12 to 15 must be suspected of betng high for the reasons given in section 4.13, 2, Three characteristics of the Japanese hematological trends should be pointed out: a) while high dose exposure groups with significant mortality showed early depression with a definite low point at four weeks, the lower dose groups showed no definite minimumat lour weeks but 4 , ; rather a continued depression until the eighth or ninth weeks. b) While the mean values for total white and neutrophile counts for even the heavily exposed groups had returned to within “ ow «The Japanese casualties were divided into groups A to H on the basis of degree of exposure as determined roughly by distance from the hypocenter and approximate degree of shielding. In groups E to H essentially no mortality ascribable to radiation exposure occurred in the first 3 or 4 months.