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Biomedical subjects

M J Swint

Publications and source records attributed to M J Swint.

7 recordsLinked to original sources
PubMed1995

Postmortem tissue contents of 241Am in a person with a massive acute exposure.

241Am was determined radiochemically in the tissues of USTUR Case 246, a 76-y-old man who died of cardiovascular disease 11 y after massive percutaneous exposure following a chemical explosion in a glove box. This worker was treated extensively with a chelation drug, DTPA, for over 4 y after exposure. The estimated 241Am deposition at the time of death was 540 kBq, of which 90% was in the skeleton, 5.1% in the liver, and 3.5% in muscle and fat. Among the soft tissues, the highest concentrations were observed in liver (22 Bq g-1), certain cartilaginous structures such as the larynx (15 Bq g-1) and the red marrow (9.7 Bq g-1), as compared with the mean soft tissue concentration of approximately 1 Bq g-1. Concentration in muscle was approximately that of the soft tissue average, while concentrations in the pancreas, a hilar lymph node and fat were less than the average. Concentrations in bone ash were inversely related to the ratio of ash weight to wet weight, a surrogate for bone volume-to-surface ratio. The distribution of activity in this case is reasonably consistent with that observed in another human case, when allowance is made for chelation therapy, and also tends to support more recent models of 241Am metabolism.

Aged↗
PubMed1991

U.S. Transuranium Registry report on the 239Pu distribution in a human body.

The distribution of 239Pu in a human whole body is reported. The body contained 246 Bq of 239Pu of which 130 Bq (52.8%) was found in the lungs and associated lymph nodes. Of the remaining 116 Bq (47.2%) that constituted the systemic deposition, 51.2 Bq (44%) were in the skeleton, 48.6 Bq (42%) in the liver, and the remainder (14%) in the rest of the body exclusive of the lungs and associated lymph nodes. An unexpectedly high concentration was observed in the pituitary. The systemic distribution of Pu in this case, when combined with the exposure history, is suggestive of an initial partitioning ratio of 239Pu between skeleton and liver of less than unity, and a tentative initial distribution from the transfer compartment of 25% to the skeleton, 50% to the liver, and 25% to the rest of the body and early excretion is proposed for this case. Older biokinetic models, when used with the available urinalysis data for this case, typically overestimated the deposition when compared with the tissue analysis results, but more recent models provided estimates in close agreement with the autopsy results.

Actinoid Series Elements↗
PubMed1991

Modified biokinetic model for uranium from analysis of acute exposure to UF6.

Urinalysis measurements from 31 workers acutely exposed to uranium hexafluoride (UF6) and its hydrolysis product UO2F2 (during the 1986 Gore, Oklahoma UF6-release accident) were used to develop a modified recycling biokinetic model for soluble U compounds. The model is expressed as a five-compartment exponential equation: yu(t) = 0.086e-2.77t + 0.0048e-0.116t + 0.00069e-0.0267t + 0.00017 e-0.00231t + 2.5 x 10(-6) e-0.000187t, where yu(t) is the fractional daily urinary excretion and t is the time after intake, in days. The excretion constants of the five exponential compartments correspond to residence half-times of 0.25, 6, 26, 300, and 3,700 d in the lungs, kidneys, other soft tissues, and in two bone volume compartments, respectively. The modified recycling model was used to estimate intake amounts, the resulting committed effective dose equivalent, maximum kidney concentrations, and dose equivalent to bone surfaces, kidneys, and lungs.

Accidents, Occupational↗
PubMed1988

Partitioning of 238Pu, 239Pu and 241Am in skeleton and liver of U.S. Transuranium Registry autopsy cases.

The content of 238Pu, 239Pu and 241Am in the liver and skeleton was estimated from radiochemical analysis of human liver and bone samples obtained at autopsy from former actinide workers whose occupational histories were suggestive of chronic inhalation exposures, with minor skin contamination and wounds documented in a few individuals. For times estimated to be several years to a few decades post intake, 75.8 +/- 15.3% of the total 241Am in the skeleton and liver was found in the skeleton (25 cases) as compared with 63.4 +/- 24.1% for 238Pu (36 cases) and 53.2 +/- 18.2% for 239Pu (43 cases). These differences are significant at the 95% confidence level. Of these cases, 34 included data on both 238Pu and 239Pu and were divided into high and low activity subgroups. The difference in the fractionation of the two Pu isotopes was apparent only in the low activity subgroup, suggesting that the difference observed between the Pu isotopes may be an artifact of the data. The different partitioning of these three nuclides suggests that the ALIs for 238Pu and 241Am may be high by about 25-50% if only the dose to bone is considered and may be high by 12-13%, based on the weighted committed dose equivalent in target organs or tissues.

Americium↗
PubMed1987

Actinide distribution in the human skeleton.

Radiochemical analysis of two half skeletons donated to the United States Transuranium Registry from individuals with occupationally incurred depositions, one of 241Am and the other of 239Pu, revealed an inverse proportionality between the concentration of actinide in the bone ash and the fraction of ash (or the calcium content of the ash). A similar relationship was observed in a third case suffering from osteoporosis, but the slope was shallower. These results suggest that accurate estimates of the total skeletal content of actinide can be made from radiochemical analysis of only a few bone samples.

Americium↗
PubMed1987

Comparison of estimates of systemic Pu from urinary excretion with estimates from post-mortem tissue analysis.

Urinalysis data for 17 individuals with known exposure to Pu were supplied to six laboratories, each of which made an estimate of systemic deposition. In general, the evaluation was done with the Langham model or one of its derivatives, and the values obtained by the laboratories for any single case were typically within a factor of two of the mean for all laboratories. The estimates made from urinalysis data typically were several-fold greater than those made from autopsy data. The results indicate that estimates based on urinary excretion overestimate systemic deposition and tend to confirm previous observations that the Langham equation underestimates urinary excretion.

Autopsy↗