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At least 145 records · Page 8Linked to original sources
PubMed1983

Differential clearance of plutonium and americium oxides from the human lung.

External X- and gamma-ray counting techniques have been used to study the retention of 238PuO2 and 241AmO2 in the lungs of a worker between 7 and 869 days after simultaneous exposure to aerosols of both oxides. From these data and measurements of early faecal excretion, it is concluded that approx. 50% of the amount of each nuclide initially deposited in the subject was removed during the first few days by ciliary clearance mechanisms. The lung clearance patterns of the other 50% differed for the two nuclides. The 238Pu was apparently cleared with a biological half-life of approximately 800 days, predominantly by systemic or lymphatic uptake, with at least part of the translocated material being subsequently deposited in bone. There was no evidence for the presence of a 30-day component of lung clearance, such as has been suggested elsewhere. In contrast, most of the residual 241Am was cleared relatively quickly, with a half-life of approximately 11 days, although a small proportion was apparently subject to long-term retention, with a half-life of approximately 900 days. The data for both oxides conflict in important respects with the patterns of lung clearance postulated by the ICRP.

Aerosols↗
PubMed1983

1976 Hanford americium exposure incident: accident description.

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.

Accidents, Occupational↗
PubMed1983

1976 Hanford americium exposure incident: psychological aspects.

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.

Accidents, Occupational↗
PubMed1983

1976 Hanford americium exposure incident: decontamination and treatment facility.

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, Occupational↗
PubMed1983

1976 Hanford americium exposure incident: organ burden and radiation dose estimates.

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.

Accidents, Occupational↗
PubMed1983

1976 Hanford americium exposure incident: hematologic effects.

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).

Accidents, Occupational↗
PubMed1983

1976 Hanford americium exposure incident: histologic and autoradiographic observations on skin.

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.

Accidents, Occupational↗
PubMed1983

1976 Hanford americium exposure incident: urinary excretion of trace metals during DTPA treatments.

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.

Accidents, Occupational↗
PubMed1984

Further studies of plutonium and americium at Thule, Greenland.

Eleven years after the accidental loss of nuclear weapons in 1968, the fourth scientific expedition to Thule occurred. The estimated inventory of 1 TBq 239,240Pu in the marine sediments was unchanged when compared with the estimate based on the 1974 data. Plutonium from the accident had moved further away from the impact point and at some locations the vertical distribution indicated a downward displacement of Pu in the sediment column since 1974. Seawater and seaplants showed no evidence of the presence of Pu from sources other than fallout; but Pu in benthos varied nearly proportionally with the levels in sediments. From the measurements of 239,240Pu in the Macoma community since 1970, the transfer factor to this community was estimated at 0.01 Bq a per Bq released to the sediments. The inventory of 241Am was 0.1 TBq. The vertical distribution of Am in sediments did not differ from that of Pu, but in benthos 241Am/239,240Pu were two times higher than in sediments. Seaplants showed the same value of Am/Pu as seawater. There was no indication of any biomagnification of Pu or Am through the marine food chains at Thule.

Americium↗
PubMed1991

Plutonium- or americium-induced liver tumors and lesions in beagles.

Plutonium-239 or 241Am administered intravenously in the monomeric citrate form was initially deposited in beagle livers principally in the hepatocytes and to a much lesser extent in the sinusoidal macrophages and connective tissues. The initial distribution was quite uniform throughout the hepatic parenchyma; however, at later postinjection intervals, depending on the amount of injected activity, the liver burden became increasingly more focal due to: (1) a progressive shift of the radionuclide from the hepatic epithelium to the macrophages; (2) the movement of such macrophages toward the portal or central regions of the lobule; and (3) the displacement of the older more radioactive tissue by regenerating hepatocytes, which generally have a much lower radionuclide content. The hepatic lesions produced by Pu or Am included: (1) necrosis and degenerative changes that were clinically serious or fatal in some of the animals injected with approximately 107 kBq kg-1; (2) marked structural and circulatory changes resulting from necrosis and focal hepatocyte hyperplasia; (3) a significant incidence of both benign and malignant primary liver tumors. In both Pu- and Am-treated dogs, the most frequently appearing neoplasm was the bile duct adenoma, followed by the cholangiocarcinoma. The most obvious difference between Pu- and Am-induced liver neoplasia was the greater frequency of fibrosarcomas and mast cell sarcomas in the Am-treated groups. Hepatomas were of relatively low frequency in animals with Pu or Am burdens. Although the incidence of bone neoplasia was high among the dogs in these studies, the risk of liver tumors, especially in the Am-treated animals, exceeded that of the skeleton in some of the lower dosage levels where the survival times were long. A risk coefficient of approximately 1200 fatal liver malignancies (10(4) beagle Gy)-1, derived from the dosage groups with long survival times, was calculated for combined Pu and Am animals. The prominence of the liver syndromes in beagles with burdens of Pu or Am indicates that humans with body burdens of 239Pu, 241Am, or other actinide elements may be at risk from radiation effects in the liver, including neoplasia development.

Adenoma↗
PubMed1994

Soft tissue concentrations of plutonium and americium in occupationally-exposed humans.

Human tissues, obtained at autopsy from 82 volunteer donors with a history of occupational exposure, were analyzed for 238Pu, 239 + 240Pu, and 241Am by chemical separation and subsequent alpha spectrometry. Concentrations of these actinide nuclides in soft tissues (testes, thyroid gland, spleen, kidneys, heart, and skeletal muscle) were compared to those of the livers in the same subjects. Tissue:liver concentration ratios were essentially constant over a wide range of liver concentrations. The spleen had consistently high actinide concentrations relative to liver; however, the heart had the greatest concentration ratio for 241Am. Testes had relatively high concentration ratios of the plutonium nuclides but low concentrations of 241Am. Skeletal muscle had low concentrations of plutonium relative to liver but high concentrations of 241Am. In the tissues studied, concentration ratios of 241Am were greater than those of the plutonium nuclides, most likely a result of more rapid excretion of that nuclide than the plutonium nuclides by the liver.

Americium↗
PubMed1995

Overview and dosimetry of the Hanford Americium accident case.

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%.

Aged↗
PubMed1995

Deterministic effects of 241Am exposure in the Hanford Americium accident case.

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.

Aged↗