23 ranged from 20 to™6months, with an average of 22.4 months. 1 To determine whether or not some pattern in physique characterized these children with retarded osseous development, several physicai measurements (from the 1959 studv) on them and on thew sibs were compared (Table 13). These anthropometric data suggested twotrends. First, the weight rankings corresponded to chronological age rankings and not to statural rankings. Second, the lack of synchrony in rankings of several measurements was noticeable in those children who were shorter than their younger sibs. This contrasted with the uniform ranking of all measurements in those whose statural ranking corresponded with the chronological age ranking. It might be speculated from these limited observations that these children were exposed to radia- tion at a particularly vulnerable age and that the resulting retardation in osseous developmentled to failure in statural growth. On the other hand, it is not possible to exclude completely the pos- malities, and in the older group 41%. Specific findings may be summarized asfollows. Electrocardiographic Findings 1. Rhythm. In the vounger group of exposed subjects, all had normal rhythm. One abnormality of rhythm was seen in a member of the younger unexposed group. [n the older groups, arrhythmia occurred in 3 of 14 exposed individuals and in 4 of 29 unexposed. 2. Conduction Times. Few abnormalities were seen. No individual in either the exposed or the unexposed group had prolonged auriculoventricular conduction time (P-R interval) above normal. Several] subjects had the shorter conduction time of 0.12 sec; this is considered normal. The intraventricular conduction time (QRSinterval) was prolonged in several subjects. Ir, she younger unexposed group, the ORSinterva: was 0.10 to 0.11 sec in one subject, sufficient to be considered right bundle branch block. In the exposed population sibility that some process unrelated to radiation damage was responsible for the retardation in skeletal development. the intraventricular conduction time was prolonged to 0.12 sec in only one individual, age 81, who had a marked degree of hypertensive arfd arteriosclerotic cardiovascular disease and cardiac ADULT ABNORMALITIES unexposed group, two showed intraventricular Table 14 is a compilation of the various physical abnormalities noted in the adult group during the 1959 and 1960 surveys. No abnormalities are included for 1960 in the unexposed group because this group was not examined in the 1960 survey. subjects the intraventricular conduction time ranged from 0.06 to 0.09 sec in the younger groups This table does not showany significant differ- ences between the abnormaiities noted in the exposed and in the unexposed populations. Results of special examinationsare discussed below. CARDIOVASCULAR SURVEY enlargement. Among 29 individuals in the older conduction times of 0.12 sec without the typical QRS complex of bundle branch block. In all other and 0.08 to 0.09 in the older. 3. Electrical Axis Deviation and Electrical Position of the Heart. ‘There were few variations. The Table 15 Electrocardiographic Abnormalities (Percent Incidence in Younger and Older Age Groups) Exposed The cardiovascular findings may be found in the table of physical abnormalities (Table ‘14). The incidence of various electrocardiographic ab- | normalities is shown in Table 15. The population was divided into a younger group, aged 20% through 49, and an older group, aged 250. In the exposed population, the younger group of 24 people showed no major abnormalities, but of the 14 older people 29% showed one or more abnor- malities, [In the unexposed population, among the younger group 15% had one or more abnor- Abnormality Rhythm A-V I-V RST T wave Unexposed Age Age Age Age 20-49 (24)* 350 (14) 20-49 (55) 250 (29) 0 21 2 L4 12 7 ? 3 0 0 0 7 7 21 4 2 11 7 14 34 *Number examined. f7 Z { r