-~ 15 = average values (7 nuclides x 6 landing periods x 4 tissues =168). The exceptions were either gr? -Nb?” or Ru? values for samples taken in September or October, the greatest average value being 10.8 pe Rut 3/g (wet) in the October sample of dark muscle. 4. “The maximum single value in 12,425 determinations samples x 7 nuclides) was 240 pc Rut 93 /g sample from a bigeye (wet) (1,775 for a dark muscle tuna caught between August 20 and September 26 at approximately 6°N and 161°W, about 350 miles northwest of Christmas Island. 5. Zinc-65 was the most abundant fallout nuclide present in the samples from fish caught prior to the 1962 series of nuclear detonations at Christmas Island. tissues were one picocurie The average values by or less per gram (less than Kt?) | the highest single value being 8.2 pc/g (wet) for a bone sample. 6. Values for csl?? did not change significantly from month to month, but the values for the other fallout radionuclides were greater at the end of the sampling period than in any previous period. 7. An unexpected monthly variation was observed 40 for K , as values for samples of tuna landed during August were one half *Oone estimate of the allowable continuous intake of Rut? for the general population is 176,000 pe per day. This value was calcu- lated from the value of 8 x 1077 uc/ce as given in the National Bureau of Standards Handbook 69 for the maximum permissible con- centration of Rul®3 in drinking water that is consumed at a rate of 2,200 cc per day, seven days per week. The NBS value was corrected by factors of 2,200 (daily water intake in ec) and 0.1 (the correction for general population exposure relative to occupational exposure).

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