Table 2.

Population breakdown by age and geographical living patterns.
Infants and
small children

Children and
adolescents

Men

Women

Age bracket (years)

0-4

5-19

20+

20+

Fraction of population (%)

16

41

22

21

Fraction of time spent in
respective areas (%):

~

Inside home

50

30

30

30

Within 10 m of home

15

10

5

10

Elsewhere in village

a)

10

5

10

Beach

5

S

S

5

Interior of island

5

15

20

15

Lagoon

0

10

10.

20

25

Other islands

- 20

shown as area 3 in Fig. 4.
and 6 are identical.

‘

5
25

As far as the external dose assessment is concerned, cases 5

Since the expected living patterns are most likely to differ

between the various age groups, it is necessary to utilize the. age distribution data
presented in Table 2.

-These data were obtained from the 1974 census taken on Kili Island

of the 784 persons who claim land rights on Bikini Atoll. 4

The geographical living patterns,

also shown in Table 2, were assumed -to be similar to those expected for the returning
Enewetak people, 1
Even though the gamma-ray exposure | rates vary widely, it was necessary, for the

' purpose of the external dose calculations, toderive the most reasonable values. ofthe- .
mean exposure rates for each specific geographical area under, consideration.
shown in Table 3.

These are

The mean exposure rates for specific areas on Bikini Island: were

obtained by weighting the mean exposure rates within each contour interval with the area

within the contour.

Since the exposure rates on Eneu Island are relatively uniform, the

mean exposure rates were chosen by inspection of. Fig.. 3. Since this survey did not include
the other islands of the atoll, it was necessary to rely. on data from-previous ‘surveys to
estimate the contribution the radidactivities on ‘these isiends:make: *° the total ‘population

dose.

Gamma exposure rate data reported. by Bennett and Beck,’2 Heid,>“Lynch et ai.,°

Gustafson,’ Smith .and Moore, ° |and Robison et al.? were used for this purpose. | Their results
in conjunction with a.simplified area weighting scheme yielded the values presented in .
Table 3,

It should be pointed out that these are rough estimates. since. the data are

scarce and‘ were collected over a span of almost ten years. The exposure rate overthe
lagoon was estimated to be 3.3 uR/hr due to the cosmic ray contribution and an additional -

-6-

ral

:

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