CHAPTER 5
INTERNAL RADIOACTIVE CONTAMINATION
5.1
PREVIOUS FINDINGS
Following the contaminating event, high levels of activity were found in drinking water and
on the external surface of plants on the contaminated atolls. Gross beta activity was found in
the urine of the majority of Rongelap and Ailinginae inhabitants, with an average of 1208
dis/min/24 hr for the Rongelap and 553 dis/min/24 hr for the Ailinginae groups 6 weeks after
exposure. The excretion rate of radioactivity was found to be three times as great in adults as
was found in the 0 to 5 year old age group. Strontium, barium, and the rare earth grouptogether contributed 75 per cent of the total beta activity of the urine at this time. The degree of
internal radiation hazard was considered too low to have contributed significantly to the acute
effects observed following exposure.
5.2
METHODS
Twenty-four hour urine specimens were obtained for analysis by the U.S. Naval Radio-
logical Defense Laboratory (NRDL), Chemical Technology Division, and by the New York
Operations Office of the Atomic Energy Commission. Methods of analysis have been described
previously.!
5.3
RESULTS
Of 53 urine specimens obtained from the Rongelap and Ailinginae groups and analyzed by
the NRDL Chemical Technology Division, detectable gross beta activity was found only in six
patients, all of whom were in the Rongelap group, and only one of whom wasover 12 years of
age. Counts ranged from 6 to 90 dis/min/24 hr. Barely detectable radioactivity was found in
23 urine specimens analyzed by the New York Operations Office.
REFERENCE
1. E. P. Cronkite et al., Study of Response of Human Beings Accidentally Exposed to Significant
Fallout Radiation, Operation Castle final report of Project 4.1.
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