data for persons weighing less than 58 kg (ICRP74). Adult reference values for
breathing rate (ICRP74) were assumed for Marshallese adults regardless of adult
body mass. At Rongelap Island, BRAVO debris passed during the afternoon, a period of light physical activity for the population. At Utirik Island, the debris passed during the night, a period of resting. At Sifo Island, a period of
light physical activity was assumed in order to estimate breathing rate during
the morning people were exposed to the fallout cloud.
ity intake were compiled and are given in Table 19.
Values for airborne activ—-
On the basis of urine results for 131;, we concluded that inhalation could not account for the estimated activity intake for
It, In fact, lethal external exposure rates would have to accompany significant radioiodine intakes if inhalation of initial cloud fallout were the dominant intake pathway
leading to the urine activity excreted on day 17. The other alternative,
resuspension of fallout, would require the air concentrations produced by the
cloud itself to be resuspended 200 times over.
age were
and 19.
Islands;
newborns
g. Total Activity Intake. Total activity intake and corresponding
tabulated in Table 20 which we compiled on the basis of Tables 15, 17,
We assumed that newborn babies inhaled activity at Rongelap and Utirik
no newborns were reported at Sifo Island (Co74). We assumed that
from Rongelap and Utirik ingested 850 ml of breast milk per day
(ICRP74) for 3 days post-detonation.
A fraction of 107) per ml of adult female
breast milk was assumed to be the fraction of mother's intake of iodine which
was transferred to the newborn (Ma81). Iodine decay between the time of intake
for the mother and the time of intake for the newborn was neglected since we
assumed breast milk to be part of the early excretion pathway out of the
mother's body. Radioiodine excreted from the long-term clearance compartments
was considered insignificant relative to total radioiodine cleared in the short
term (Ma81).
h.
Derivation of !3!r Intake Based on Bikini Ash and 89sr and 140g
in Urine on Day 45 Post-Detonation.
Cronkite (Cr56) reported ©%Sr and !40ga
urine activity excretion on day 45 post-detonation for six adults from Rongelap
Island.
The mean urine activity excreted on day 45 was 8.9 Bq (2.4 ~ 10 “4 Ci)
of 89sr and 2.2 Bq (6.0 x 10 “> uci) of 140g,. Whole-body retention functions
given by ICRP (ICRP72) for injection of strontium and barium are
Ro (t) = 0.60¢ ~0.25t +0.299( 40.20) ~0.18 (0.555e ~6.5x107> "40 .445e -2.6x107¢ 8)
Raa’) = 0.38e
-0.75t
+0.191(t+0.007)
-0.237
(0.564e
~1l -09x10
~4
¢ 10.436e
_
“4
4.36x10°"t) (6)
where t is in days and R(t) is the injected fraction remaining on day t. The
fecal-to-urine ratios for excretion of injected Sr and Ba were 0.25 and 9.0, re-
spectively (ICRP72).
Correcting for 45 days of decay, the estimated activities
injected into the systemic region of the body were 2.3 x 104 Bq (0.61 wCi) and
6.1 x 10> Bq (16.4 wCi) for 8¥sr and
140Ba, respectively.
If fallout was di-
rectly ingested as a single intake of dust at 0.5 day post-detonation, then the
intake of 140g,, 89sr, or 1311 would be in the same ratios as the activity per
unit area for these nuclides given in Table 13. Thus, we roughly estimated the
- 54 =