COMBINED WEIGHTED DATA* (BIGLOGICAL AGE SCORES) 190 | gol. aor T T o EXPOSED * UNEXPOSED 3 COMBINED WITH STANDARD ERROR MEANS T 1 TT | 9 re 0.99 "8* ye 0.5140.38 2 +0.01 x? 7Or 6O0r- — uo z a e $0 iw | & 40 a ~ 30 * COEFFICIENT FOR AGE _ CORRELATION OF EACH CRITERIA USED TO WEIGHT SCORES BEFORE SUMMING 20 ~~ ioe ° 20 Fig. 15. | ** CORRELATION WITH AGE SIGNIFICANT AT 1% LEVEL {et 30 40 Lot 50 60 AGE FIGURE 15 7O 80 L 30 Biological age scores in exposed and unexposed groups. “age curve" (Fig. 15} shows that there is less change in the younger age groups than occur after about age 40. Mean values for exposed and unexposed are not significantly different. Discussion Though the criteria presented in this report show changes which are definitely correlated with chronological age on a group basis, such correlation is much less accurate on an individual basis. These tests of ageing are least useful in the younger age groups (20-40 years of age), since most of the criteria either are not present until later or if present show slight increase during this age period. Therefore, more sensitive tests are needed to show ageing in these groups. Effects of radiation on ageing as measured by these parameters were not detected in this population. Perhaps the tests were not sensitive enough to detect such effects at the level of radiation exposure sustained, It is not known if any of the ''ageing parameters" which are ordinarily associated with senescence are necessarily associated with radiation ageing, since the latter is very poorly defined or understood, Even if they were, it i ' 4 & ; i i \ S0125b4 2 oeOTIS . - 357 -