Plutonium Handbook a Guide to Technology (Volume II) (Plutonium Injection Experiments)

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A Guide to the Technology Pacific Nortliwest Laboratories Hattelle Memorial Institute Prepared untler tlie auspices of die United States Atomic Energy C:o~ii~iiission Division of 'Ieclinical Information

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per aample can be achieved. With this sensitivity it is po-cible to detect as little a9 1% of the recommended maximum permissible body burden (0.04 p c ) 90 days after intake, approximately 3% after one year, and about 8% after 5 years. For workers chronically exposed to possible plutonium intake, it is recommended that a sampling frequency be used that is capable of detecting deposition as low as 1% of the permissible deposition. One sample per year collected from workers not regularly assigned to plutonium processing areas or who are infrequent visitors to these areas will suffice. Annual sampling gives the capability of detecting approximately 3% of the permissible limit, assuming intake occurred a year earlier. For employees who do no plutonium work and who have access to but do not work in a plutonium processing facility, a surveillance program of sampling once every 5 years is sufficient. At this time interval a 0.05 dis/min per sample detection level will detect approximately 8% of the permissible body burden. Coverage of a major portion of the plant personnel provides one index of the success of the radiological control program for plutoSpecial sampling is necessary if accidental exposure to plutonium occurs. If the potential of intake appears great, the first voiding after the exposure may be used. Single voidings, usually 100 to 250 ml, collected as soon as 2 hr after a contaminated injury, have indicated an intake of plutonium. These samples will only give an indication of the magnitude of intake and any possible need for some therapeutic treatment to reduce permanent body deposition. A detailed study of internally deposited plutonium requires complete collection of urine on a 24-hr ba4s to obtain the most reliable results for estimating body Smears of the external nares can be used to indicate possible plutonium intake after an exposurk' incident. Filter paper such as Whatman No. 41, cut into 1- by 2-in. VALUES OF A AND R. strips and wrapped around the tip of a cotton applicator, makes satisfactory swabs that can bt: flattened out, dried, and counted. A useful technique consists sf collecting a dry smear from each nostril, and then using swabs dampened with water or saline solution. Contaminated nasal smears as low as a few hundred dis/min indicate a fair probability that some plutonium has entered the body and may be detected in the urine. Unfortunately, experience has not shown any reliable relationship between the level of nasal contamination and the resultant body burden. 24-5 EVALUATIONOF INTERNALLY DEPOSITED Plutonium deposited in humans is detected and measured by the activity found in the body excreta. This has been established for many years and is still the most sensitive procedure for detecting internally deposited plutonium. An empirical relationship of body burden and plutonium excreted in urine and feces was established by LanghamS for the most simple case of soluble plutonium that reaches the bloodstream. By administering plutonium as Pu4+ citrate intravenously to several human subjects, Langham derived the following general relationships8 for excretion in urine and In these equations L is time in days after the administration of plutonium and E,, and E f are the respective daily excretion rates in urine and feces expressed as fractions of the initially administered dose. Data covering a period of approximately 1700 days were used to establish these general relationships. It is assumed that the equations describe the excretion rate of plutonium in the blood system regardiess of mode of entry. Figure 24.1 shows the relationship derived by Langham between the excreted plutonium and time after intake. Integrating the expression will give the total fraction of the body burden excreted during the period of interest.

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24-6 SPECIAL THERAPEUTIC TREATMENT 843 treatment is relatively constant for an individual and does not vary as a function of time after plutonium intake. The factor increase, honever, is directly related to the excretion rate obscrvcd just prior to treatment. This relationship has been found valid for periods of a few days o r several years after the initial intake in all cases observed. Since plutonium excretion for humans decreases very rapidly after exposure, the most beneficial treatment period therefore will be immediately following intake when the excretion rate is at its maximum. tered intermittently during a period of about 7 months, with the treatment consisting of both intravenous and oral administrations over a period of 71 days and 21 days respectively within the 7-month period. The usual course of treatment for intravenous administration consisted of two dosages daily for 5 successive days fol-. lowed by 2 days of rest. Periodically longer rest periods were given in order to evaluate results of treatment and estimate the body burden. Oral administration of 2-g dosages twice daily for 5 successive days was given, followed by another administration of enteric-coated 1-g tablets four times daily. There was no loss of efficiency noticed as treatment was continued for an extended time. After a rest period of several days, the excretion rate dropped to the level originally observed prior to treatExperience with CaDPTA shows markedly greater efficiency in accelerating plutonium excretion than was observed with CaEDTA. I n a of long-term administration of DTPA, it was shown that significant amounts of plutonium may be eliminated. However, the effectiveness gradually decreases throughout the course of treatment. After 50 weeks of treatment the effectiveness of DTPA decreased to approximately 20% of the initial results. The residual effect of DTPA treatment has been observed to be very good. That is, the iesults of one treatment in increasing plutonium excretion can be measured over a period of about 3 week. Thus, effective results are obtained through intermittent administration. One-g dosages were given 2 days per week for 3 consicutive weeks. Treatment periods were alternated with 3 weeks of no treatment and with occasional periods up to 5 weeks for observation of results. During 1 year actual treatment covered 22 weeks and a total dosage of 43-g of DTPA was administered. Intermittent measurement of fecal elimination indicated it to be 10% or less of the urinary excretion. The net result of the DTPA treatment over a period of 1 year was the elimination of approximately 8% of the estimated total body burden acquired 2.5 years previously. cium DTPA in the form of l - g capsules increased urinary excretion by factors ranging front 3 to 19, and fecal output was iricreascrl factors of 2 to 16. No longterm treatment data are available on orally administered DTPA. In comparison, oral administration is much less effective' than intravenous administration but still appears to be about equal to intravenously administered EDTA. Toxicity studiesIs with EDTA and DTPA have not been extensive, being limited primarily to small animals and to treatment. cases where very small dosages have been administered. Therefore, these chelating agents should only be administered under the direction of a medical physician familiar with this type of treatment. NBS Handbook 69, Maximum Permissible Body Burdens and Maximum Permissible Concentrations of Radionuclides in Air and Water for OccupationHanford Atomic Products Operation, General Electric Co., Jan. 4, 1954. Thompson, Absorption of Plutonium Through Skin of the Rat: Rates of Penetration and Methods for Skin ford Atomic Products Operation, General Electric inated Injury Case Study and Associaled Use of NacEDTA us a Decontaminating Agent, USAEC Retion, General Electric Co., Aug. 3, 1960. R. H. Wilson, Decontamination of Human Skin After Immersion in a Plutonium Solution, USAEC Report HW-42030,Hanford Atomic Products Operation, General Electric Co., Mar. 30,1956. nium in Wounds, in Proceedings of the Second United Nations International Conference on the Peaceful Uses of Atomic Energy, Geneva, 1958, Vol. 23, pp. 142-143, United Nations, Geneva, 1958. in a Patient with a Plutonium-Contaminated Injury, ses, Am. Ind. Hyg. Assoc. Quart., 17: 305 (1956).