284 CONARD ET AL, 40 TT ro TTT mf, 30 vT I ° mm uw Re S20 uw | <_< | a 10 OL Oo 8 PLATELETS a py 24 40 56 72 6 1 2 3 DAYS MO TIME AFTER EXPOSURE ‘ 4 YR Fic. 2. Chronological changes in platelets of Rongelap people after exposure to 175 r vt whole-body radiation from fallout. Points represent mean counts of males >1) vears of age and females of all ages. Stars represent comparison population mean counts at that time. 6-296 2 level of blood elements have occurred from year to year m both exposed and unexposed populations. 2. Neutrophils During the first few weeks after exposure, the neutrophils fluctuated considerably, then gradually fell to a low of about 50% of the comparison population at about the sixth week (Tig. 1). Recovery was slow, and it was not until the l-year examination that the counts returned to the comparison population level. They have been found to be essentially the same as the unexposed group at 1, 2, 3, and + years postexposure. 3. Lymphocytes By the third day after exposure the mean lymphocyte level had fallen to about 55 % in the adults and 25 % in the children of the level of the unexposed comparison population (Fig. 1). The levels remained low longer than the neutrophils and have been very slow in recovering. There was little recovery by 6 months, but an up- ward trend has since occurred. After 3 years the lymphocytes were slightly helow the mean level of the comparison population for all age groups, and distributional studies of individual counts showed more lower counts in the exposed groups. The 4-year study showed the highest level thus far attained (3600 cells/mm? compared SG t2303 - *