.,.’ Dr. Robert Conrad -2- Assuming that a systemic plutonium body burden of 40000 pCi exposes the of bone to 29 rem per year, 130 pCi would correspond to an exposure % O.1 rem per year to the bone. To me, this is an insignificant exposure. . All of the above discussion is based on the assumption of uptake of soluble plutonium into the blood stream. I have difficulty in imagining how such a continuous soluble exposure could occur. Inhalation is a possible route of exposure, but the long hold up times for insoluble plutonium in the pulmonary region and lymph nodes would make detection by urine sampling difficult (to <a-ythe least) after only three years of potential exposure. As indicated in our phime conversation our concern about plutonium exposures at LASL are at a much higher level than those expected for the Bikini natives. The urine and fecal sampling programs at LASL is given in the accompanying document, LA-3836-SOP. An early version of the computer program we use to compute systemic body burden from urine assays is described in the accompanying reprint. A later version of the computer code’is currently in use, but still in development, and has not yet been documented. The urine analysis technique at LASL does not claim the sensitivity you quoted from the Health and Safety Lab in New York. However, it has been published in Health Physics 11, 737-742 (1965) by Campbell and Moss. The following slight modif~~ation has been added to the published procedure: “Hydgroen peroxide in small quanities is added to the ash solution before the ion exchange steps to ensure formation of tetravalent plutonium, elution is accomplished with 0.36 ~HCl - 0.01 ~HF.” We also discussed correcting low volume urine samples to true 24 hr excretion. I indicated that I had reservations about appl,yingsuch corrections for natives of on Bikini atoll, and I still entertain such reservations. However, in answer to your inquiries on ways to correct, Group H-5 has developed the folIowing techniques for use here at LASL, using data collected under controlled conditions: Corrections are made by estimating the “elapsed time” (minutes) represented by the sample analyzed, and multiplying the amount of plutonium determined in the “elapsed time” —--—_—-urine by 1440 “ Creatinine method: Elapsed time (rein)= 73 + 0.69 X (mg creatinine in sample) Specific Gravit,y-Volumemethod Elapsed time (rein)= 21220 X (spec. gravit,y- 1) + Volume (cm3) of sample - 415.