6 age group, males, were consistently higher than those of the adult group in absolute counts but consistently lower as percentage of control. There was no evidence of hemorrhage into tissues, even though in 11 individuals platelet count levels reached between 35,000 and 65,000 per cubic milli- meter. Two women menstruated when their platelet counts were 150,000 and 130,000 per cubic millimeter respectively. Both experienced excessive menstrual bleeding, insufficient to cause them concern, which subsided withouttherapy. qT qT a T T q - t afi 7 MAJURO CONTROLS, MALE <10 (16) 400r 7 MAJURO CONTROLS, FEMALE, ALL AGES (59! RONGELAP Ploteleis PLATELETS « 105 300 Lae “e . e MAURO CONTROLS aor MALE >10 (18} —*..—_—_—_ ok’ t t “ * e * =~ ~ @ MALES, <10 (1) & MALES,>16 (18) O FEMSLES, ALL AGES (33) - 005 awl. 10 al. 20 i 30 i 40 i 30 POST EXPOSURE Dar 1 60 I 70 "Tes Fig. 2.—Mean platelet changes in highest exposure group (64 people). Six months after the accident, blood cell counts showed only slight increase over previous ones during the last week (10th) of the initial observation period and were still below control levels. Follow-up studies at one year after the accident showedthat the neutrophil counts of the exposed individuals were back to the controllevel; however, the lymphocytes, monocytes, eosinophils, and platelets werestill below control levels, though they were 90Gb 2644