65
hypothyroidism in the two most growth-retarded
boys with subsequent growth response to thyroid
hormone treatment. Thyroid function tests in
cases with thyroid abnormalities also indicated
reduced thyroid function in someotherchildren.
Preliminary indications are that thyroid hormone
treatmentinstituted in the exposed population in
September 1965 is having a beneficialeffectin reducing thyroid nodules and stimulating growth of
children. The importance of these thyroid developments in the Marshallese is discussed.
OTHER STUDIES
Hematological studies show that the leukocyte and
platelet levels of the peripheral blood of the exposed Rongelap people seem to have recovered to
levels equalto those of the unexposed population.
The blood levels of the Utirik population showed
no obvious abnormalities and were similar to those
previously noted.
Chromosomestudies of white cells of 51 peripheral
bleod cultures showed a low incidence of 2-hit
aberrationsin the exposed people which was quite
significantin view of the absence of any such aberrations in the comparison population.
Blood volume andredblood cell volume studies showed
that people of Rongelap havesignificantly reduced levels as compared with Americans, Cau-
casiansliving in the Marshall Islands did not generally show this phenomenon.
Aging studtes have been repeated with the addition of several new parameters (vibratory sense,
light extinction test, body potassium levels, and
blood serum cholesterol) and with morerefined
statistical analysis. Curves of response for each
aging parameter andan over-all biological age
score curve are presented. Nosignificant increase
in aging effects in the exposed population compared with the unexposed population could be detected. The over-all correlation of the biological
age scores with chronological age was good. It was
concluded that the tests employed may not have
been sensitive enough to detect subtle effects of
aging at this exposurelevel.
ESTIMATION OF INTERNAL BODY BURDENS
OF RADIONUCLIDES
In the 1965 survey whole-body counting was
done on 179 people with an 11%-in.-diameter
Nal (T1) crystal in a portable shadow-shield type
of counter. The Rongelap residents exposed in
1954 and the unexposed residents wereindistinguishable by this method, both groups showing
elevated '*’Cs body burdensof 10 to 20 nCi/kg
body weight, or slightly less than 1 wCi total body
burden and about Moco this much for °°Co body
burdens. These levels are about the same as
or slightly lower than those reported previously for
the 1961 survey. Urine specimenswerealso analyzed radiochemically for °°Sr and '*7Cs, The *°Sr
levels remain nearly the same as those found in
1961. In a comparison of the '*'Cs excretion rate
with the body burdens, a meanfractional excre-
tion rate of 0.00553/day was found.
Acknowledgments
The cooperation of many agencies and persons
was necessary to carry out these surveys success-
fully. The authors are deeply grateful for valuable
assistance to manyindividuals too numerousto
name. Weare particularly grateful to the people
of Rongelap and Utirik Atolls for their cooperation in these examinations.
Manyofficials of the Atomic Energy Commis-
sion, particularly Dr. Charles L. Dunham andDr.
H.D. Brunerandtheirstaff of the Division of Biol-
ogy and Medicine, and Mr. W.A. Bonnet and Mr.
Neil Rassmussen of the Honolulu Operations Office, were most helpful in coordination of arrange-
ments and in supporting the surveys in every way
possible.
Wearegrateful to the officials of the Depart-
ment of the Interior, particularly Mrs. Ruth Van
Cleeve and the officials of the Trust Territory
of the Pacific Islands, including High Commissioners Mr. W.M. Goding and Mr. W.R. Noor-
wood; the Acting Director of Medical Services,
Dr. L.A. Howe; the District Administrator for the
Marshall Islands, Mr. Dwight Heine, and his As-
sistant, Mr. Danny Akimoto; the Director of the
Majuro Hospital, Dr. John Iaman, and members
of his staff; the Trust Territory Representative at
Kwajalein, Mr. R. McKay, and Dr. Ezra Riklon
at the Ebeye Hospital; all were most helpful.
The Pacific Missile Range Facility at Kwajalein
wasofgreatassistance in furnishing necessaryairlifts and materials. Mr. Frank Granich and others