FOOD-CHAIN KINETICS OF RADIONUCLIDES
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Table 6—SUMMARY OF HYPOTHETICAL VALUES THAT, IF INDICATED
BY MEASUREMENTS MADE AFTER ENVIRONMENTAL CONTAMINATION BY A SINGLE FALLOUT EVENT, WOULD IMPLY TOTAL DOSES
‘OF 0.5 REM TO THE SKELETONS OR THYROIDS OF INFANTS
CONSUMING 1 LITER OF MILK PER DAY
Hypothetical values*
89Sr
131]
Initial concentrations on pasture plants, Pp»
Maximum concentrations in milk, M,
Time after fallout, tmax
61,0 pe/g
4500 pc/liter
8 days
13.7 pe/g
1850 pe/liter
4 days
Maximum concentration in human tissue, H;
Time after fallout, t max
Total dose (at t = ~)
27 pe/gt
30 days
0.5 rem7T
1580 pe/gtT
15 days
0.5 remf
Total intake (to t = ©)
1.60 x 105 pe
2.63 x 104 pe
*Calculations were based on Eqs. 8 to 14 and the parameter values listed
in Table 5.
+Based on a 700-g skeleton or a 2.0-g thyroid.
eral population...” or an average of 0.5 rem/year “... to be applied
to suitable samples of an exposed population group.” Average annual
intakes of >2000 pc ®Sr/day or >100 pc '4I/day “... would be presumed
to result in exposures exceeding the RPG... .”
With the assumptions of a skeleton weight of 700 g and a thyroid —
weight of 2.0 g, Eq. 14 and the parameter values listed in Table 5 indi-
cate that total annual intakes of 160,000 pc of **Sr or of 26,300 pc of
‘S17 could result in doses of 0.5 rem/year to the bones and the thyroids
of infants.
These values are lower than those indicated by the FRC
(i,e., 720,000 pc **Sr/year and 36,500 pc *I/year) because the parameter values in Table 5 are more pessimistic than those adopted by the
FRC,
For further comparison with the FRC’s recommendations, we have
estimated the hypothetical values of various measurements which, if
obtained following a single fallout event, could result in doses of 0.5
rem to the bones and thyroids of infants. These hypothetical values are
given in Table 6.
Tables 1 and 2 show that initial concentrations of '*“I on plants in
various parts of the Sedan fallout field were about four times higher
than the initial concentrations of "Sr. The estimates given in Table 6
indicate that initial concentrations of **Sr about 4.5 times higher than
those of '“"I are required to deliver comparable doses to humantissues.
We might therefore suppose that '!I is considerably more hazardous
than ®*°Sr in an area contaminated by close-in fallout.
The data given in Table 2 indicate that the initial concentration of
‘ST on plants in the vicinity of Currant, Nev., was approximately 1000 +
150 pc/g. Similar plant samples collected in a hot spot (centered near
Fruitland, Utah), which was discovered after the Small Boy detonation