RESULTS AND DISCUSSION
Daily Activity Ingestion Rates
Daily activity ingestion rates were calculated for dosimetrically significant nuclides post-return.
An exponential decline was proposed for the inges-
tion rate within a population subgroup and initial reference values are given in
Figures 10 through 14 (June 1, 1957, was assigned as a return date to Rongelap).
Figure 10 demonstrates the differences in ingestion of 13766 for various population subgroups.
This undulating pattern was exhibited by
137,
S;
90
Sr, and
65
“2n,
nuclides for which sufficient data existed for analysis.
Differences in ingestion rates of the stable element at the same geographic location have been shown to occur among members of a population (ICRP
23).
Age-dependent diet studies for ingestion of Cs for urban Japan have values
varying from 11 pg a for adults to 8.6 ug al for children.
at
Sr in a western-
a7}
3,600 ug a? for 13 year olds and fell to a mean of 1,900 ig al for adults. Zn
in the United Kingdom rose from 2 to 40 mg at, the higher value of Zn being
observed in adult tea drinkers.
Fe ingestion in a western-type diet has a mini-~
Mum at age 3 and maxima at ages 1 and 20 years.
Co is ingested at a rate of 20
Lg a for Japanese adults and half thieamount for children.
The Marshallese
population also exhibits dietary changes as a function of age.
The authors of
the Marshall Islands Diet and Living Pattern Study (Na80) observed coconut sap
being used as a major food supplement for infants, and later in adult life as a
major source of daily fluid intake.
Since coconuts and coconut tree sap pro-
vided the major source of 13To8 on Bikini Atoll (Le80, Mi80), the shape of Figure 10 was
in agreement with the observed diet pattern.
22