radiological half-life of 1357Cs and where the
initial intake is the same regardless of age, the
integral 30-, 50-, and 70-y dose equivalents are
slightly greater when intake begins as an adult
than for intake beginning at any other age. This
results from the combination of changing body
weights, fractional deposits, and biological
30-, 50-, and 70-y dose equivalents are less when
concentration of 137Cs in food with time. For
example, when intake begins as an infant, the
137Cs_ concentration in food has declined by
about 35% by the time the infant reaches 18 y of
age, whenthe dietary intake is greater and the
longer.
for infants and children because !37Cs accounts
for about 97% of the total estimated effective
dose equivalent at the atolls via the ingestion
pathway and 90Sr for less than 3%.
Doses from 137Cs and %Srare insignificant
through the inhalation pathway as compared
Consequently, if the intake of 137Cs for an infant
to that via ingestion (Robison et al., 1987; ICRP,
or child were equal to that for the adult (which
it is not based on available dietary information
from the Marshall Islands), the estimated
integral 30-, 50-, and 70-y dose equivalent would
Consequently, the relative magnitude of the
integral dose equivalent among infants,
intake begins as an infant or child than when
intake begins as an adult.
.
Even if the ?9Sr intake for infants and
children were significantly higher than what
we have estimated, the total integral 30-, 50-,
and 70-y effective dose equivalent from both
137Cs and %Sr would be greater for adults than
half-life for 137Cs_ with age and the reduced
biological
half-life
of
137Cs
1979; Cristy et
al.,
1984;
Kendall,
1986).
children, and adults can be determined by
still be similar to that estimated for adults.
evaluating the ingestion pathway; that
analysis indicates that the estimated effective
In the case of 90S,, the dose commitment per
integral dose equivalents for adults due to
unit intake is greater by about a factor of 5 for
intake beginning at ages 0 to 5 y than for intake
beginning as an adult. However, when agedependent differences in intake of 90Sr via the
ingestion of 137Cs and 99Sr is a conservative
estimate for intake beginning in infancy and
childhood.
diet are accounted for, the estimated integral
References
Aarkrog, A. (1963), "Caesium-37 from Fall-out in Human Milk," Nature 197, 667-668.
Abraham, S., M.D. Carroll, C.L. Johnson, and C.M. Villa Dresser (1979), Caloric and Selected Nutrient
Values for Persons 1-74 years of Age: First Health and Nutrition Examination Survey, United
States 1971-1974, U.S. Department of Health, Education and Welfare, DHEW Publication No.
(DHS) 79-1657, Series 11, No. 209.
Adams,N. (1981), "Dependence on Ageat Intake of Committed Dose Equivalents from Radionuclides,”
Phys. Med. Biol. 26, 1019-1034.
Bengtsson, L.G., Y. Naversten, and K.G. Svensson (1964), "Maternal and Infantile Metabolism of
Caesium," Assessment of Radioactivity in Man, Vol. II, International Atomic Energy Agency,
Vienna, Austria, pp. 21-32.
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