99-21-1994 12:19 P.019 BNL-MED. DEPT. 5162825311 in Chapter III of reference (1). HEMATOLOGIC OBSERVATIONS It ise generally considered that changes in the blood are the mist sensitive biologic indices of exposure of living human beings to radiation. Accordingly ex- tensive simple hematologic studies vere performed on the Marshalles@. Sines there were no previous hematologic studies on the exposed Marshallese, it|was necessary to set up control groups of non expesed Marshalled of the same age andjsex distribution for comparative purposes. I shall restrict my comments to the findings in the eroup from Rongelap sines the tanporal sequence of events are identical if all of the ex posed groups. Of course the depression was less marked in the leas|severly exposed groups. Neutrophile Count The absolute neutrophils count of both the younger and oldeF age groups fell during the second week to a valuo approximating 70 to 80% of that of the controls. Folloving the depression there vas an oscillation roughly around the control value until about the 30th post exnosure day at which time there was a prperessive decreare in the blood count with minimum values being attained around the 45th day after ex- posure. It is of interest, that the depression in the children, 1 of age was greater than in the individuals who were greater than 5 Following this maximal depression there was a slow return of the nqutrophile counts towards normal, However at 6 months they were still depreesed. years the neutrophile counts were back to the control level. Atj Howe one year and two at 3 years there Was a drop in the absolute mean neutrophile count but this allso occurred in the control population. It is not known whether lowered counts represent a popiu- lation trend as has been noted in the Japanese for both irradiated jand non irradiated populations, or vhether it is merely a statistical fluctuation thed . Lymphocyte Count, More work {fs necessary on this point. : fo. oe : wes in this type of study. is to be expected

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