of the February 1980 Personnel Monitoring Field Trip to Enewetak and Ujelang Atoll Results In February 1980 members of the BNL Marshall Islands Radiological Safety Program conducted a field trip to Japtan and Enewetak Islands, Enewetak Atoll and Ujelang Island, Ujelang Atoll. The purpose of this trip was to obtain baseline radionuclide body burden data on the Enewetak population prior to the repatriation of Enewetak Atoll in April 1980. Personnel monitoring was accomplished through whole body counting and collection of 24 hour of urine samples from all persons age 5 years and older. Each person who was whole body counted was asked to provide the survey team with a one liter urine sample. Past experience indicated that this represented the approximate urine output for 24 hours; and it was more productive to ask the subjects to submit a ‘“fullbottle” than to ask for a ● ’24 hour sample.” At Ujelang, old and infirmed persons who were not whole body counted were requested to provide urine samples. Participation in all aspects of the personnel monitoring program was voluntary. Bioassay samples were acidified with ten (10) grams of boric acid to retard biological degradation then sealed for shipment to Brookhaven National Laboratory. Upon receipt, the samples first will be analyzed spectrometrically for gamma emitters and then radiochemically for strontium and yttrium. Results from these analyses should be available prior to January 1, 1981. .:.. J The total number of urine samples that were collected on this field trip is currently being determined. Our records indicate that 291 samples were collected at Ujelang Atoll, 33 at Japtan and 15 at Enewetak. More samples which had not been collected at the time of our departure are expected from these last two islands. Reports from Holmes and Narvcr representatives at Enewetak Atoll indicate that they had been collected and acidified. The total shipment of urine samples was delivered to BNL on March 18, 1980. Whole body counting was conducted with two independent chair counting systems mounted in a large modified ● ’Matson” transportainer. In this counting geometry, an individual sits in a chair partially surrounded by two inches of lead shielding. A sodium iodide detector is positioned in front of the subject. The solid angle seen by the detector permits detection of photons emitted from all parts of an adult subject’s body between the neck and the knees. This ~ounting geometry allows the subject easy entry and egress from the whole body counter with minimal loss of system sensitivity relative to the bed geometry. Smaller subjects have more of their body within the solid angle while larger subjects have somewhat less. Figures 1 and 2 illustrate the counting geometry used and physical arrangement of one side of the whole body counting trailer. The chair body counters were calibrated for three geometries 1) an adult standard man, 2) an average Marshallese adolescent and 3) an average Marshallese juvenile. The population selected to determine the average height and weight of Marshallese adolescents and juveniles was the former Bikini Atoll population. Gamma spectra obtained at Enewetak Atoll and Ujelang Atoll were analyzed using the calibration standards which best matched the sex, height and weight of the individual subject. ..- /’ Table 1 summarizes the physiological and radiological data obtained from the February field trip. Statistical analysis performed on the mean CS-137