roentgenograms were obtained for most of them (1961 to 1963), even the youngest members of this group were already approaching skeletal maturity. C.: Results Statural growth data are given in Tables 1 and 2 of Appendix III and in Figure 1. Three age groupings were used: 0 to 5, 5 to 10, and 10 to 18 years old as of March 1, 1954. The two younger age groups were combined (age 0 to 10) for some of the analyses. The numbers of exposed subjects in the 10 to 18 year age groups were extremely small. Figure 1 demonstrates a consistent retardation of stature among the boys exposed at age <l0. The differences are statistically significant only between ages 9 and 16, apparently because thyroid medication was administered to the exposed people on Rongelap after 1963. Figure 1 also indicates that statural retardation occurred in both subgroups (age 0 to 5 and 5 to 10 at exposure) but was more marked in the younger one. Statural growth in the few boys exposed at age >10 showed no differences from that in unexposed boys. Among the girls the statural growth curve (Fig. 1) for those exposed to fallout at age 0 to 10 was significantly retarded at chronological ages of 6 to 7 years compared with that for the unexposed girls. Figure 1 also shows that the statural retardation occurred in girls exposed at age <5 but not in those exposed at age 5 to 10, and disappeared by about age 9. The curves for girls exposed at age 10 to 18 are quite similar to those for unexposed girls. These findings suggest that retardation in stature among the exposed girls occurred earlier and was less prominent and of shorter duration than among the exposed boys. Osseous maturation among exposed boys was significantly retarded compared with that in unexposed age peers (see Fig. 2). This retardation was particularly prominent when the boys were 14, 15, and 16 years old, and Figure 2 indicates that it occurred in both age groups (those aged <5 and aged 5 to 10 in 1954). Figure 2 also shows a similar comparison among girls. For the entire group exposed at age <10, skeletal maturation lagged significantly behind that in the unexposed girls until about age 10, and thereafter the gap progressively narrowed. Figure 2 suggests that this retardation in osseous maturation among exposed girls occurred primarily among those exposed at age <5 and to a very limited degree in those exposed at age 5 to 10. D. Discussion Growth studies on young people exposed to radiation from the atomic bombs in Hiroshima and Nagasaki showed that their adult heights were significantly lower than those of the controls (55). Similar analyses were carried out on statural data from inhabitants of Rongelap and Ailingnae Atolls who were exposed as children to fallout radiation. The presumptive adult (final) stature for each exposed child is tabulated in Appendix III. This stature is either the plateau value when several measurements remained the same, or the - 28 CG. Cre ci CTD latest measurement (made after the subject was >20 years old) if the latest prior measurement had continued to show increase.