Dungy/Morgan/Heotis/ Branson/ Adams


turies, although interisland travel by large outrigger
sailing vessels permitted the evolution of a relatively
homogeneous society.
The Marshall Islands were made a United Nations
Trust Territory under United States trusteeship following World WarIT. In 1954, during a nuclear weaponstest series, the populations of Rongelap and Utirik atolls, numbering 253 including those in utero,

were exposed to radioactive fallout from a United
States thermonuclear test on Bikini atoll [4]. Since that
time these exposed populations havereceived annual
medical examinations and treatment carried out by
the Medical Department of Brookhaven National
laboratory under contract to the Atomic Energy
Commission (now the US Departmentof Energy)[5].
Over the years, the Brookhaven medical team has, by
virtue of its periodic field visits to the exposed populations, come into contact with a muchlarger general
population which is resident in these islands. To the
extent that its schedule and resources permit, the team
has volunteered assistance to the local health authorities and a measure of direct patient care to the larger
group. Approximately 1,500 Marshallese have been
seen in this way, including a large number of children.
Theyare the subject of this report.
The annual medical examinations of exposed and
unexposed adults have included evaluation for
anemia. Hb electrophoresis has been performed on
blood specimens from approximately 200 Marshallese. No variant Hbs have been detected. Splenomegaly is distinctly rare and when present has been associated with nonhematologic disorders. Malaria is not
present on the atolls. Evaluation of selected individuals with microcytosis has yet to lead to a confirmed diagnosis of either a or f thalassemia. Glucose-6-phosphate dehydrogenase deficiency has not been identified among several hundred personstested. It therefore appears probable, from the results of routine
evaluations of the adult population, that genetically
determined anemias have, at best, a low prevalence

among the Marshallese.

tion-exposed parents. In the aggregate the study population repre-

sented nearly 3.4%ofall Marshallese under 16 years of age. Parents

or guardiansofall children were awareofthe testing and consented
to their child’s participation. Copies of blood test results were
placed on individual health records and givento the parent/guardian. Venous blood was collected in EDTA-anticoagulated vacutainers (Becton Dickinson, No. 6453) and skin puncture specimens
were collected in 80-yl finger-stick diluting pipettes and diluted in
Haema-Line 2 (Baker Instruments, Allentown, Pa.) before analysis.
Hb and MCYvalues were determined by direct measurement on a
Baker 500 electronic cell sizer and counter; calibration of the cell
counter was donewith control cells supplied by the manufacturer.
Free erythrocyte protoporphyrin (FEP) determinations were performed on light-protected EDTA-anticoagulated specimens after
they had been transported at 4°C to the Hematopathology Laboratory, University of California, Irvine Medical Center. Zinc proto-

porphyrin levels were assayed with an internally calibrated (hematocrit 35%) commercial hematofluorometer employing front surface illumination and digital computer output (Environmental
Science Associates, Bedford, Mass.). One hundred ul of whole
blood were placed on a glass coverslip and introduced into the instrument. All determinations were performedin triplicate. The laboratory’s normal range (100 subjects) is 13.8 + 10.9 ug/di and values exceeding 60 yg/dl are considered definitely abnormal. Five
whoie blood controls were drawn to indicate possible changes associated with storage. The coefficient of variation for these controls
was 0.3%.
Statistical analysis was performed utilizing BMDP software [6]
on a DEC VAX-11 computer. Among the types of analyses performed were simple and detailed data descriptions including analysis of variance and covariance,frequencies and correlations.
All Hb and MCV values were used in analysis for differences
among groups(i.e., island of residence, history of parental radiation exposure). Because of insufficient numbers, values of persons
<1 and > 13 years of age were excluded in evaluation of normal
ranges. To derive approximate age-specific normal ranges for Hb
and MCV for Marshallese children the method of Dallman and
Siimes [7] was used. This procedure derives limits by excluding outlying values prior to analysis. The exclusion limit for Hb ts an MCV
> 5% from the mean: for MCVit is an Hb > 1 SD from the mean. ft
is acknowledged that a considerable number of normal values will
be amongthe excluded, but the strength of the method is that most
common abnormalities will be removed. In foilowing this approachin analyzing the Marshallese data, the mean rather than median values were used because the small numberof determinations
in each age group madepercentile analysesstatistically weak.
The appropriateness of excluding any Hb greater than the mean
was questionedin view of the rarity of pathologically high Hb levels in children. For this reason exclusion of Hb values on the basis
of MCV values > 5%from the mean was recalculated to encompass
only the Hblevels fess than the mean.

Subjects and Methods
Venousorfinger-stick blood specimens were obtained from 563
Marshallese children ranging from 6 months to 15 years of age as
part of their medical examination. The recorded age wasthatof the
most recent birthday. The study population resided on 4 atolls;
Rongelap (n = 110), Utrik (n = 158), Kwajalein (n = 169) and Ma-

juro (n = 126). Two hundred and thirteen were children of radia-

IU Zab b


Age-specific mean values for Hb and MCVin the
1- to 13-year age groups (table I) show the previously
reported increase with age [8, 9]. The FEP, in contrast,

Select target paragraph3