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NCRP Report 156 describes soluble radionuclide retention kinetics in a wound, segregated into four retention categories: weak (W), moderate (M), strong (S), and avid (A). An alternate single-parameter model, the negative power function, t, is presented in this paper to describe the time behavior of radionuclide retention. With this mathematical description, γ is a single parameter that can be used to assign the wound retention category rapidly. Using the power function description of wound retention, the various wound categories present as straight lines on log scales with different slopes corresponding to the various retention categories. Regression analysis of average retention values in NCRP 156 shows γ = 0.735 ± 0.132, 0.514 ± 0.015, 0.242 ± 0.016, and 0.053 ± 0.023 for the weak, moderate, strong, and avid categories, respectively. A case study is presented (REAC/TS Registry case 1284) where a power function is shown to fit retention data in a Pu/Am hand wound up to 2,000 d (5.4 y) post-accident.

Purpose: It is important to understand the significance of alpha (α) radiation-induced bystander effects (RIBE) and its relative biological effectiveness (RBE); this is because the phenomenon is not universal and the mechanism is unclear and because the RBE is widely varying and projected to be very high. Materials and methods: Isolated lymphocytes from healthy volunteers ( n  = 10) were exposed to either low fluence α-particles ( 241 Am), γ-rays ( 60 Co), or X-rays (225 kVp and 6 MV). Co-culture methodology was employed to investigate bystander effects (BEs). Chromosomal aberrations (CA) and micronucleus (MN) formation were used to study the BE and calculated RBE. Results: Lymphocytes directly exposed to the types of radiation used showed a dose-dependent increase in the frequency of CA and MN; dose independent increases in the frequency of these chromosomal damages in co-cultured bystander cells, implies that all three types of radiation-induced a BE. The calculated RBE at the level of 5% induced aberrations varied between 9 and 20. Conclusion: The magnitude of low fluence α-particle induced RIBE is higher than in low LET (linear energy transfer) radiation. The RBE also varies depending upon the endpoints used and adds up to targeted effects. Since the endpoint of CA is considered as an important and early marker of risk prediction, the RIBE and RBE using CA as a marker are relevant for radiation protection purposes.

This article introduces the first accident of internal contamination with plutonium (Pu) or americium (Am) in Japan for which treatment was carried out. An accident of internal contamination with Pu and Am occurred at a Pu research facility at Oarai-town of Ibaraki prefecture in Japan. A plastic bag containing these radionuclides ruptured when five workers were inspecting a storage container in a hood. As a consequence, these workers were internally contaminated with Pu and Am. Although contamination on the body surface was observed in all five workers, a positive nasal swab was detected in only three of them. A chelating agent, calcium diethylenetriaminepenta-acetate (CaDTPA), was administered to all of them including the two workers without a positive nasal swab. However, bioassay detected a significant amount of Pu and Am in urine after administration of DTPA in these two workers, whereas the levels of these nuclides were below minimum detectable levels in urine before the administration. Since the prevalence of adverse reactions in DTPAs is low, the present results suggest that administration of DTPA can be used for the diagnosis of internal contamination even when a nasal swab is negative or contamination around body orifices is not detected.

3,4,3-LI(1,2-HOPO) has been identified as an excellent alternative for DTPA for decorporating actinides, such as Pu and Am, after internal contamination. Efforts have been focused on its application through oral administration. When 3,4,3-LI(1,2-HOPO) was encapsulated with biocompatible, biodegradable nanoparticles made of chitosan, its release from the nanoparticles to lung fluid, observed in in vitro experiments, exhibited an extended release profile. These observations were very encouraging, as this nanomedicine could lead to a reduction in the dosing frequency required to achieve the decorporation efficacy of unformulated 3,4,3-LI(1,2-HOPO) itself. In vivo release tests as well as actinide decorporation experiments, using an inhalation exposure animal model, will follow.

During the aftermath of a radiological accident or attack, the rapid identification of individuals who have internalized medically significant amounts of material is paramount to guide medical and public health decisions. This paper explores the utility of hand-held, pancake GM detectors to determine if an individual has inhaled Sr, Cs, Pu, Pu, or Am in quantities requiring treatment. Additionally, ingestion of Sr or Cs was considered. Both Sr and Cs were modeled in equilibrium with their progeny, but the progeny of Pu, Pu, and Am were excluded. Treatment thresholds are defined using the National Council on Radiation Protection & Measurements' (NCRP) clinical decision guides (CDGs). Using Monte Carlo N-Particle (MCNP) modeling software, a human phantom and detector were modeled to determine the activity required to achieve a detector reading of twice background 1, 7, or 30 d post-ingestion or post-inhalation. Modeling found that inhaled Pu, Pu, and Am are detectable only if the contaminated individual inhaled thousands-fold more material than the CDG. This lack of detectability means that hand-held GM detectors are inappropriate for initial screening for americium or plutonium and that more intensive screening is necessary to confirm suspected contamination. Cesium-137, by contrast, could be detected at levels 10- to 100-fold lower than the amount requiring treatment, allowing quick differentiation between contaminated and uncontaminated individuals. Surprisingly, Sr was detectable within a factor of 2 of the amount requiring treatment. Detection of Sr was due primarily to bremsstrahlung radiation from beta interactions with calcium in bone. While rapid screening could identify individuals contaminated by Cs and possibly with Sr, further screening of identified individuals is necessary to establish medical need. However, these contaminated individuals could still be prioritized for further testing and possible presumptive treatment. Based on the findings of this study, concepts of operation for the use of hand-held survey meters should be developed for the screening of individuals potentially internally contaminated with Cs and Sr.

A software suite on biokinetics of radionuclides and internal dosimetry intended for the occupational health practitioners of nuclear industry and for expert opinions has been developed under Borland C++ Builder™. These computing tools allow physicians to improve the dosimetric follow-up of workers in agreement with the French regulations and to manage new internal contaminations by radionuclides such as Pu and/or Am after diethylene triamine penta-acetic acid treatments. In this paper, the concept and functionalities of the first two computing tools of this MADOR(®) suite are described. The release 0.0 is the forensic application, which allows calculating the derived recording levels for intake by inhalation or ingestion of the main radioisotopes encountered in occupational environment. Indeed, these reference values of activity are convenient to interpret rapidly the bioassay measurements and make decisions as part of medical monitoring. The release 1.0 addresses the effect of DTPA treatments on Pu/Am biokinetics and the dose benefit. The forensic results of the MADOR(®) suite were validated by comparison with reference data., (© The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Radioactive material deposited in multiple organs of the body is likely to confound a result of an in vivo measurement performed over the lungs, the most frequently monitored organ for occupational exposure. The significance of this interference was evaluated by measuring anthropometric torso phantoms containing lungs, liver, skeleton, and axillary lymph nodes, each with a precisely known quantity of 241Am uniformly distributed in the organs. Arrays of multiple high-resolution germanium detectors were positioned over organs within the torso phantom containing 241Am or over proximal organs without activity to determine the degree of measurement confounding due to photons emitted from other source organs. A set of four mathematical response functions describes the measured count rate with detectors positioned over each of the relevant organs and 241Am contained in the measured organ or one of the other organs selected as a confounder. Simultaneous solution of these equations by matrix algebra, where the diagonal terms of the matrix are calibration factors for a direct measurement of activity in an organ and the off-diagonal terms reflect the contribution (i.e., interference or cross-talk) produced by 241Am in a confounding organ, yields the activity deposited in each of the relevant organs. The matrix solution described in this paper represents a method for adjusting a result of 241Am measured directly in one organ for interferences that may arise from 241Am deposited elsewhere and represents a technically valid procedure to aid in evaluating internal dose based upon in vivo measurements for those radioactive materials known to deposit in multiple organs.

Purpose: Americium-241 ((241)Am) presents a potential risk for nuclear industry workers associated with reactor decommissioning and aging combustible materials. The purpose of this study was to investigate Am renal retention after actinide contamination by wounding in the rat., Materials and Methods: Anesthetized rats were contaminated with Mixed Oxide (MOX) (7.1% Plutonium [Pu] by mass and containing 27% Am as % total alpha activity), Pu or Am nitrate following an incision wound of the hind leg. Times of euthanasia ranged from 2 hours to 5 months after contamination. Pu and Am levels were quantified following radiochemistry and alpha-spectrophotometry., Results: Initial data show that over the experimental period the proportion of Am in kidneys as a fraction of total kidney alpha activity was elevated as compared to MOX powder indicating a specific retention in this organ. The percentage of Pu was similar to the powder. After MOX contamination, kidney to liver ratios appeared to increase more markedly for Am (from 0.2 at 7 days to 0.6 at 90 days) as compared with Pu (0.1 at 7 days to 0.2 at 90 days). In accordance with tissue actinide retention the dose from Am to the kidney increases with time. For comparison, the ratio of estimated equivalent doses due to Am to kidney is 1.5-fold greater than for Pu (around 90 versus 60 mSv)., Conclusion: After actinide contamination of wounds, Am is concentrated in the kidneys as compared to Pu leading to potential exposure of renal tissue to both alpha particles and gamma radiation.

Background: Treatment of actinide-contaminated wounds may be problematic because of contaminant physicochemical properties, dissemination and anatomical localization. This study investigates different chelation/resection protocols after contamination of rats with americium (Am) or plutonium (Pu) nitrate or mixed oxide (MOX; uranium (U), Pu oxide)., Methods: Anesthetized rats were contaminated with Am or Pu nitrate (moderately soluble) or MOX (insoluble) following wounding of hind leg muscle. DTPA (diethylene triamine pentaacetic acid) treatment (30 μmol/kg) was immediate or delayed, systemic or local and combined or not with wound resection. Actinide urinary and tissue levels were measured., Results: Comparison of Pu nitrate and MOX dissemination at the wound site indicated a more heterogeneous localization of MOX particles. In all cases DTPA treatment reduced target tissue (bone, liver) activity levels even if DTPA treatment was started 7 days after contamination. Surgery alone increased urinary excretion suggesting release from the wound site but no subsequent increases in organ retention (bone, liver) were observed. The combination of surgery and DTPA increased Pu excretion and reduced tissue levels markedly., Conclusion: This rodent model of actinide wound contamination has been used to test different treatments. It provides evidence of activity release as a result of surgery that seems not to lead to increased organ retention.

Comparisons between results of in vivo counting measurements of americium burden and results from radiochemical analyses of organ samples taken at autopsy of 11 cases of former Mayak workers were made. The in vivo counting measurements were performed 3-8 y before death. The best agreement between in vivo counting measurements for americium and autopsy data was observed for the skull. For lungs and liver, the ratios of burden measured by in vivo counting to those obtained from radiochemical analyses data ranged from 0.7-3.8, while those for the skull were from 1.0-1.1. There was a good correlation between the estimates of americium burden in the entire skeleton obtained from in vivo counting with those obtained from autopsy data. Specifically, the skeletal burden ratio, in vivo counting/autopsy, averaged 0.9 ± 0.1. The prior human americium model, D-Am2010, used in vivo counting measurements for americium in the skeleton to estimate the contents of americium and plutonium at death. The results using this model indicate that in vivo counting measurements of the skull can be used to estimate internal doses from americium in the Mayak workers. Additionally, these measurements may also be used to provide a qualitative assessment of internal doses from plutonium.

Radioactive lightning rods (RLR) were manufactured and installed in Brazil for almost two decades, before they were prohibited in 1989. Structures protected by this type of lightning preventers included residential buildings, schools, commercial and industrial facilities, among others. It is estimated that about 3.4 TBq of 241Am were used by manufacturers, and a total of 75,000 pieces with a mean activity of about 46 MBq were in the market. While only a fraction of the total has been recovered, the almost twenty thousand pieces already collected at the Nuclear and Energy Research Institute (IPEN) had their sources successfully separated from the remaining recyclable metal scrap and are now encapsulated in lead containers for final disposal.

A 1985 plutonium puncture wound resulted in the initial deposition of 48 kBq of transuranic alpha activity, primarily 239+240Pu and 241Am, in a worker's right index finger. Surgical excisions in the week following reduced the long-term residual wound activity to 5.4 kBq, and 164 DTPA chelation therapy administrations over 17 mo resulted in urinary excretion of about 7 kBq. The case was published in 1988, but now 24 y of follow-up data are available. Annual bioassays have included in-vivo measurements of 241Am in the wound, skeleton, liver, lung, and axillary lymph nodes, and urinalyses for plutonium and 241Am. These measurements have shown relatively stable levels of 241Am at the wound site, with gradually increasing amounts of 241Am detected in the skeleton. Liver measurements have shown erratic detection of 241Am, and the lung measurements indicate Am but as interference from activity in the axillary lymph nodes and skeleton rather than activity in the lung. Urine excretion of Pu since termination of chelation therapy has typically ranged from 10 to 20 mBq d, with Am excretion about 10% of that for 239+240Pu. Annual routine medical exams have not identified any adverse health effects associated with the intake.

A calibration phantom was developed at the University of Cincinnati (UC) to determine detection efficiency and estimate the quantity of activity deposited in the axillary lymph nodes of a worker who had unknowingly sustained a wound contaminated with 241Am at some distant time in the past. This paper describes how the Livermore Torso Phantom was modified for calibrating direct, in vivo measurements of 241Am deposited in the axillary lymph nodes. Modifications involved milling a pair of parallel, flat bottom, cylindrical holes into the left and right shoulders (below the humeral head) of the Livermore Torso Phantom in which solid, 1.40-cm-diameter cylindrical rods were inserted. Each rod was fabricated using a muscle tissue substitute. One end of each rod contained a precisely known quantity of Am sealed in a 1-cm-diameter, 2.54-cm-deep well to simulate the axillary lymph nodes when inserted into the modified Livermore Torso Phantom. The fixed locations for the axillary lymph nodes in the phantom were determined according to the position of the Level I and the combined Level II + III axillary lymph nodes reported in the literature. Discrete calibration measurements for 241Am in the simulated axillary lymph nodes located in the right and left sides of the thorax were performed using pairs of high-resolution germanium detectors at UC and Lawrence Livermore National Laboratory. The percent efficiency for measuring the 59.5 keV photon from Am deposited in the right and left axillary lymph nodes using a pair of 3,000 mm2 detectors is 2.60 +/- 0.03 counts gamma-1 and 5.45 +/- 0.07 counts gamma-1, respectively. Activity deposited in the right and left axillary lymph nodes was found to contribute 12.5% and 19.7%, respectively, to a lung measurement and 1.2% and 0.2%, respectively, to a liver measurement. Thus, radioactive material mobilized from a wound in a finger or hand and deposited in the axillary lymph nodes has been shown to confound results of a direct, in vivo measurement of the lungs.

Radioactive lightning rods were manufactured in Brazil until 1989, when the licenses for using radioactive sources in these products were lifted by the national nuclear authority. Since then, these rods have been replaced by the Franklin type and collected as radioactive waste. However, only 20% of the estimated total number of installed rods has been delivered to the Brazilian Nuclear Commission. This situation causes concern, since there is the possibility of the rods to be disposed as domestic waste. In Brazil, 64% of the municipal solid waste is disposed at garbage dumps without sufficient control. In addition, (241)Am, the radionuclide most commonly employed, is classified as a high-toxicity element, when incorporated. In the present study, (241)Am migration experiments were performed by means of a lysimeter system, in order to evaluate the risk of contamination caused by radioactive lightning rods disposed as common solid waste. (241)Am sources removed from lightning rods were placed inside lysimeters filled with organic waste that was collected at the restaurant of the Instituto de Pesquisas Energéticas e Nucleares. The generated leachate was periodically analyzed, and characteristics such as pH, redox potential, solid content and the concentration of the radioactive material were determined. The equivalent dose for members of the public was calculated considering ingestion of contaminated drinking water as the major path of exposure. Estimated doses were about 20-times below the effective dose limit of 1 mSv year(-1) for members of the public as recommended by the International Commission on Radiological Protection. This suggests the radiation risk caused by lightning rods disposed at uncontrolled garbage dumps to be low. It should be noted, however, that the number of investigated lightning rods was quite small. The results of this study might therefore not be entirely representative and should be interpreted with care. They provide, however, a very first basis for characterizing the transfer of (241)Am from lightning rods to the human food chain.

The article describes a case of slowly soluble plutonium and americium compounds entering human body via skin wound. During the wound healing, the authors followed features of biokinetics of the radioactive substances, determined the major route of their excretion, evaluated efficiency of surgical d-bridement and complexation medicine (pentacin). clinical and biophysicdata collected could serve to increase efficiency of urgent therapeutic and prophylactic measures aimed to individuals with wounds contaminated with radioactive substances.

The examinees demonstrated definite effects caused by total influence of Am-241 and Pu-239: chronic radiation sickness with diffuse pneumosclerosis, chronic toxic radiation bronchitis and peripheral blood changes (reactive alterations and stable lower platelets and reticulocytes count), microfocal hypoplasia, osteodysplasia, reactive hepatopathy. Frequency of these effects increased with higher radiation exposure and did not depend on the age.

Purpose: To compare tumour induction in CBA/H mice, principally osteosarcoma and acute myeloid leukaemia, resulting from exposure to the alpha-emitting nuclides, uranium-233, plutonium-239 and americium-241, and to relate differences between the three nuclides to the pattern of dose delivery within tissues., Materials and Methods: Each nuclide was administered intraperitoneally in citrate solution to three groups of adult male CBA/H mice at levels of activity which gave estimated life-time average skeletal doses of about 0.25-0.3 Gy, 0.5-1 Gy and 1-2 Gy. Animals were carefully monitored and sacrificed as soon as they showed signs of ill health; tumours were identified by standard histopathological techniques., Results: Statistical modelling by Cox regression showed that, considering all three nuclides together, there was a highly significant increase in risk of death from osteosarcoma or myeloid leukaemia with increasing dose rate. For osteosarcoma, the effect was significantly greater for 239Pu than 241Am, while separate analysis for 233U showed no significant increase with increasing dose rate. For example, the increase in relative risk of death from osteosarcoma for an increase in life-time average dose rate to bone of 1 mGyd(-1) was 4.2 (2.7-6.5) for 239Pu, 2.3 (1.4-3.4) for 241Am and 1.1 (0.4-3.1) for 233U. For myeloid leukaemia, there was no significant difference between 239Pu and 241Am in the effect of dose rate. The increase in relative risk from myeloid leukaemia for an increase in average dose rate of 1 mGyd(-1) was 1.8 (1.1-2.8) for 239Pu, 2.0 (1.4-2.9) for 241Am and 1.5 (0.8-2.7) for 233U. Significant increases in renal and hepatic carcinomas were also recorded in animals exposed to 233U and 241Am, respectively. Studies of the distribution of the nuclides within the skeleton, published separately, have shown differences in their retention in individual bones and within bone. The proportions of decays occurring near to endosteal bone surfaces and throughout bone marrow were in the order: 239Pu> 241Am>233U., Conclusions: For osteosarcoma, the relative effectiveness of the nuclides in terms of average bone dose, in the order 239Pu>241Am>233U, is consistent with the proportion of dose delivered near to endosteal surfaces. For myeloid leukaemia, the greater effectiveness of 239Pu and 241Am than 233U is consistent with their accumulation in marrow.

The effect of Medetopect, a food additive, on the metabolic kinetics of transuranics (239Pu and 241Am) has been studied experimentally in white mongrel rats following chronic intake by ingestion. The Medetopect application has been shown to be advantageous for reduction of the 239Pu and 241Am absorption from and content of the gastrointestinal tract of the animals.

Chromosome analyses were performed on peripheral lymphocytes from seven radiation workers exposed to external gamma-radiation within maximum annual permissible dose limits during 11 to 22 years of employment. Five years prior to blood sampling, six workers had additionally incorporated the alpha-emitting radionuclide 241Am which contributed between five to 25% of the total accumulated whole body dose in five workers and about 70% in one worker. For the radiation workers as a group, both the mean frequencies of symmetrical translocations measured by fluorescence in situ hybridisation (FISH)/chromosome painting and dicentrics + ring chromosomes scored in first division metaphases of conventional preparations were significantly elevated compared with respective controls. The mean biodosimetry estimate for the group was 270 mSv when based on stable translocations which compares well with the mean dose of 247 mSv based on official dosimetry records. The lower mean dose estimate of 160 mSv based on unstable dicentrics is compatible with the well-known loss of dicentrics from the circulating blood with time after exposure.

Histopathology and qualitative autoradiography studies were undertaken on bone removed at autopsy from USTUR Case 246. The histopathology examination revealed extensive bone marrow peritrabecular fibrosis and decreased cellularity in most samples. In addition, histological indicators suggest that bone cell turnover was suppressed at most sites, although turnover was found to be essentially normal in a vertebral body sample. The autoradiographic studies showed that bone turnover that had occurred resulted in the redistribution of americium within bone. However, surface deposits of americium remained conspicuous at many sites, particularly those with low bone growth activity. A few percent of the americium was present in the bone marrow. The dosimetric and toxicology findings indicate that current assumptions about the metabolic behavior of bone-seeking radionuclides are likely to be unrealistically simplistic.

Lifetime follow-up of USTUR Case 246 demonstrated the lack of severe biological effects resulting from his exposure to 241Am. Deterministic effects observed were limited to hematological changes, including lymphopenia and thrombocytopenia. These hematological changes were consistent with those observed in experimental animals following actinide exposure. Cataracts were removed from the left and right eyes at 547 and 1,030 d after the accident, respectively, but were considered to be trauma-induced rather than radiation-induced. No abnormal findings were reported from gross or histological examinations of tissue samples removed at autopsy, other than those resulting from the subject's preexisting cardiovascular disease.

Postmortem examinations of selected tissues from an individual who received a massive internal exposure to 241Am and succumbed to pre-existing cardiovascular disease 11 y later are summarized. Significant findings include acellularity of the marrow, marked peritrabecular fibrosis, and a lack of bone surface remodeling, confirmed by bone-surface alpha-spectrometry; tissue concentrations of 241Am that indicate bone and liver as the primary deposition sites, in general agreement with the new ICRP model, but not with the older models; a distribution of 241Am in soft tissues in general agreement with that observed in animals; and the absence of any other gross or microscopic pathological findings attributable to the exposure. Cumulative absorbed doses to the bone, bone surface, liver, and lung were 18, 520, 8, and 1.6 Gy, respectively. The probability of not observing a fatal cancer based on BEIR-IV risk factors for these absorbed doses was 12%.

Pacific Northwest Laboratory performed a study to evaluate the consistency of internal dosimetry assessments. A total of eleven laboratories, including DOE sites and NRC licensees, participated in this intercomparison study. Participants were asked to respond to five actual exposure scenarios, previously used in a similar European study. The participating dosimetrists assessed the data of the test scenarios and calculated results in terms of estimated radionuclide intake and the resulting internal doses. To maintain confidentiality, results are given without identifying any site. Except for one scenario, the results showed that the standard deviation of the final results on committed effective dose equivalent for each exposure scenario was about 30-50% of the mean value, giving a consistency slightly greater variant than that of the European study. The discrepancies can be attributed to variations in 1) the interpretation and statistical treatment of the bioassay data; 2) the biokinetic models applied; and 3) the computational tools used. This represents a preliminary study; further intercomparison testing is needed to fully evaluate the problem of dose-assessment inconsistency.

A case of plutonium injury of the left hand is used to explain the correct management. In addition to radical surgical excision under repeated monitoring of radioactivity, it is obligatory to commence parenteral chelation therapy with DTPA. Close cooperation with radiological technologists is necessary. Discharges and used bandages have to be analysed for their radioactive content before elimination as radioactive waste. Isolation of the patient is not required. The relevant government department has to be contacted. A health center for radiation victims with special measuring equipment is desirable.

A chronological account is given of the general medical management of a patient involved in an americium exposure incident.

An accident is described which involved the explosion of an ion-exchange column containing about 100 g of 241Am. A chemical operator was injured in this accident, receiving acid burns and superficial cuts on the upper part of his body. From 1 to 5 Ci of 241Am is estimated to have been deposited on the injured worker and on his clothing.

A Hanford worker received an intake of 241Am by skin absorption and inhalation which was later evaluated to be in excess of 1 mCi. The skin was the main pathway for introduction of 241Am into the body; however inhalation was also a significant pathway. Intensive DTPA therapy prevented 99% of 241Am which entered the blood stream from being deposited in the internal organs. Retention and distribution of 241Am in various internal organs and tissues was determined from sequential measurements in vivo using several arrangements of externally located scintillation detectors. The organ and tissue retention and distribution have been followed for longer than 5 yr. Excretion patterns and estimates of radiation dose to the lung, liver, bone and skin are described.

Salient features of the 1976 Hanford americium exposure incident are discussed. Comparisons are made with previous human and animal exposure data, and conclusions drawn relative to the injured workman, to health physics practices, and to the adequacy of current exposure limits.

An injured worker, contaminated with more than 6 mCi of 241Am required special treatment and housing for 4 months. This paper is a description of the design and management of the facility in which most of the treatment and housing occurred. The problems associated with contamination control, waste handling, supplies and radiological concerns during the two-stage transfer of the patient from a controlled situation to his normal living environment are discussed in detail.

Accidents involving exposure to radiation or radioactive materials may involve an unusual degree of emotional trauma. Methods that may be employed in dealing with such trauma are discussed in relation to a specific accident in which a radiation worker was injured and seriously contaminated with 241Am.

Hematologic evaluation of an individual with an initial systemic body burden of approximately 200 mu Ci 241Am revealed a significant (P less than 0.01) reduction of total leukocytes, neutrophils and lymphocytes. This effect on total leukocytes and neutrophils was evident approximately 30 days after exposure, appeared to stabilize at about 3 months after exposure, and remained at this lower level through a 52-month observation period. The effect on lymphocytes was apparent by 3 days after exposure, stabilizing at approximately 50% of pre-exposure values for about 7 months, with a return to pre-exposure levels in the following 4 yr. There was a progressive and significant (P less than 0.001) decline in platelet counts during the 52-month post-exposure period. The pattern of response in erythrocyte parameters was complex. Immediately after the accident, these values were less than the pre-exposure mean level; they gradually increased (P less than 0.001) for approximately 2 yr and then began a progressive decline (P less than 0.001).

Urine samples from a person treated intravenously with diethyl-enetriaminepentaacetate (DTPA) salts for 3 yr to promote the excretion of 241Am were assayed for 24 elements including almost all of the trace metals currently recognized as essential for good health. Zinc was found to be the only metal excreted more rapidly than normal. An 18-mg urinary loss of body zinc was found to be associated with each 1-g injection of Na3CaDTPA. Use of either Na3ZnDTPA or Na3CaDTPA combined with oral dosages of ZnSO4 appeared to completely compensate for this loss, and it is unlikely that the patient experienced any zinc deficiency due to the DTPA treatment.

The 241Am measurements on the donor's body, followed by an analysis of each bone of the skeleton, have provided the best available calibration factors for measuring the 241Am content in the skeletons of the living. These calibration factors have already been useful in measuring the skeletal burden of several workers in the nuclear industry. This study has shown that differential linear scanning provides good results on the content of various parts of the skeleton. Previously used methods of head or leg counting for estimating total skeletal content of 241Am were also found to provide good results. These studies confirm previous recommendations that in-vivo measurement of the skull probably provides the best estimate of 241Am in the skeleton; however, other positions such as the knee are also found to be bilaterally symmetrical for identical bones on the right and left sides of the body. A comparison of measurements on the donor's body with those of other people with skeletal burdens of 241Am shows that differences in skeletal distribution do exist and are probably due to the age of the person, the duration of the skeletal 241Am burden,and perhaps the physical activity of the person. Additional measurements and studies are planned on the remaining half of the skeleton and they should further improve the accuracy of in-vivo measurements of 241Am in the human skeleton.

The distribution and retention of intravenously injected 241Am in the skeleton of the female rat has been investigated using autoradiographic and radiochemical techniques. The studies were designed to assess the dosimetric and toxicologic implications of an 241Am intake by man. They showed that in the rat approximately one third of the intravenously injected 241Am was deposited in the skeleton where it appeared to be retained with a long biological half-time. The studies also showed: 1 241Am is initially deposited onto all types of bone surface including endosteal surfaces, periosteal surfaces and those of the vascular canals within cortical bone, but seems to be preferentially deposited onto those that are resorbing, 2 Bone accretion results in the burial of surface deposits of 241Am, 3 Bone resorption causes the removal of 241Am from surfaces, 4 Resorbed 241Am is retained by phagocytic cells (probably macrophages) in the bone marrow, 5 The transfer of 241Am from the phagocytic cells in the marrow to adjacent bone surfaces seems to occur, (local recycling). 6 The possibility that some of the 241Am removed from the bone surfaces enters the blood and is redeposited in bone, (systemic recycling) cannot be dismissed. These results show that 241Am deposition and redistribution in bone shares many characteristics with other 'bone surface-seeking radionuclides' typified by 239Pu. Consequently, it is suggested that a similar model to that used to calculate annual limits of intake for 239Pu in man would be suitable for the calculation of corresponding values for the 241Am isotopes.

Examination of biopsies from exposed and relatively unexposed areas of the face revealed changes that were consistent with actinic elastic degeneration associated with solar exposure, except in areas in which sources of alpha radiation were detected in the upper dermis. In those areas, particles judged to be ion-exchange resin were found within a few macrophages and extracellularly among connective tissue fibers. Elastic fibers in those areas showed more advanced degenerative change than fibers not closely associated with heavy concentrations of alpha radiation.

Los Alamos National Laboratory has analyzed autopsy tissue for the USTR, as a part of its study of the uptake, distribution and retention of Pu and other transuranic elements in occupationally exposed workers since 1978. In April 1979, Los Alamos received the internal organs and bone samples from the first whole-body donation to the USTR. The donor was known to have an internal deposition of 241Am. All soft tissue, the bones from the right half of the skeleton, and the odd-numbered vertebrae were received at Los Alamos in February 1980. The bones were subdivided along anatomical areas of interest. All soft tissues and bone specimens were analyzed for their 241Am content. A total deposition of 147.4 nCi 241Am was measured. Approximately 18% of the 241Am remaining in the body (disregarding that in the left hand), was found in the soft tissues, and 82% was in the bones and teeth. The soft tissues and organs containing the largest amounts of 241Am were the combined soft tissue (striated muscle, connective tissue and skin) 8.8%; liver, 6.4% and respiratory tract, 1.5%. The remaining organs accounted for 0.9% of the systemic burden.

The estimated systemic burden of 0.3 muCi 241Am, made by the resident health physicist, has been compared to postmortem measurements using in-vivo counting equipment and radiochemical analysis of the donor's body. The health physicist's estimate was based on in-vivo measurements and urine excretion data obtained while the donor was still working, and it was logically assumed that the intake occurred about 1954 as a result of inhalation of Am-contaminated air. Based on additional data obtained by postmortem analysis, it seems more reasonable to assume for the purpose of scientific study and evaluation that the intake occurred in 1953, primarily as the result of a contaminated wound. Evaluations of the systemic burden using that assumption and three models indicate that the amount initially deposited could have been in the range of 0.2-1.1 muCi 241Am.

An accident resulted in the deposition on an injured workman's skin surfaces, in acid-burned areas and in lacerations, of something in excess of 6 mCi 241Am. This paper describes the external decontamination procedures used, the change in americium content of the skin during the course of treatment, and some of the unusual problems encountered from the extrusion of foreign material and flaking of skin and scar tissue.

Detailed external measurements were made of internally deposited 241Am in a nuclear chemical operator involved in an americium exposure accident at the Hanford plant. Despite some interference from high-level external contamination, quantitative measurements of the 241Am content in the lung, liver and bones were made starting on the third day after the accident. The rate of excretion of 241Am from these organs was determined. The 241Am embedded in the skin of the face and head was carefully mapped. The distribution over the total length of the body was also determined. Linear and rectilinear scanners, gamma cameras, large and small scintillation detectors, proportional counters, and Si(Li) and intrinsic germanium detectors were used to evaluate the internal deposition. Methods of calibration for quantitative measurement included simulation of the 241Am activity in both phantom and cadaver parts.