740
RIVERA
Table 2— ESTIMATED ™Sr/CALCIUM
RATIOS IN DIETS OF NEW YORK CITY
RESIDEN TS*
Picocuries
Picocuries
per gram
of calcium
Year
Year
per gram
of calcium
1956
6
1960
10
1957
6
1961
10
1958
10
1962
14
1959
13
1963
32
*Diet levels prior to 1956 are assumed to
have been negligible.
past *’Sr/calcium ratios in bone due to exposure to varying ‘Sr levels
in the diet since 1956, as calculated with Eq. 1 and the factors listed
in Table 1, the doses received so far by New York City residents of
different ages were calculated (if a factor of 2.7 mrad per year to bone
per picocurie of *°Sr per gram of calcium in bone is assumed.*) These
dose estimates are shown in Fig. 2. The doses accumulated so far are
very low compared to the dose delivered to bone from natural radio-
activity, i.e., approximately 130 mr/year (page 21 of Ref. 6). The
doses from *Sr that will ultimately be delivered to New YorkCity
PTTTTTTITTT1TTrrritititttiirittiyry
——— CALCULATED 1962
PICOCURIES PER GRAM OF CALCIUM
Lo
—a— OBSERVED 1962
—— CALCULATED 1963
—o— OBSERVED 1963
6k
_
—_—— — —s~— — -
oLLLLi ty tit | dpe ts et tt te
0
2
4
6
8B
0
12
14
%16
#%18
20
22
24
26
28
AGE
Fig. 1—Strontium-90 in bone in New York City residents.
30