PubMed Health⌕ Search

Biomedical subjects

R L Kathren

Publications and source records attributed to R L Kathren.

At least 55 records · Page 3Linked to original sources
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↗
PubMed1988

Implications of human tissue studies for radiation protection.

Through radiochemical analysis of voluntary tissue donations, the U.S. Transuranium and Uranium Registries (USTR) are gaining improved understanding of the distribution and biokinetics of actinide elements in occupationally exposed persons. Evaluation of the first two whole-body contributions to the USTR revealed an inverse proportionality between actinide concentration and bone ash. The analysis of a whole body with significant 241Am deposition indicated a significantly shorter half-time in liver and a greater fraction resident in the skeleton than predicted by existing models. Other studies with tissues obtained at autopsy suggest that existing biokinetic models for 238Pu and 241Am and the currently accepted models and limits on intake, which use these models as their basis, may be inaccurately implying that revisions of existing safety standards may be necessary. Other studies of the registries are designed to evaluate in-vivo estimates of actinide deposition with those derived from postmortem tissue analysis, to compare results of animal experiments with human data, and to review histopathologic slides for tissue changes that might be attributable to exposure to transuranic elements. The implications of these recent findings and other work of the registries is discussed from the standpoint of this potential effect on biokinetic modeling, internal dose assessment, and safety standards and operational health physics practices.

Actinoid Series Elements↗
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↗
PubMed1986

Acute accidental inhalation of U: a 38-year follow-up.

The intake and deposition of U in three men accidentally exposed to soluble natural U compounds in an explosion in 1944 were reevaluated 38 y later by the U.S. Uranium Registry. The initial lung depositions were estimated to be about 40-50 mg of U based on the fragmentary urinary excretion data obtained shortly after the accident. The initial long-term bone deposition was estimated from individual excretion curves and was 410 micrograms (5.2 Bq) in the highest exposed individual, which resulted in an integrated 40-y dose equivalent to the bone surfaces approximately 2 mSv (200 mrem). Medical and health physics examinations of two of the men 38 y after the accident revealed no detectable deposition of U nor any physical findings attributable to U exposure. One of the exposed individuals showed an altered clearance pattern for U shortly after the accident, possibly from pulmonary edema associated with concomitant exposure to acid fumes.

Accidents, Occupational↗
PubMed1985

A World War II uranium hexafluoride inhalation event with pulmonary implications for today.

Two individuals were exposed to massive quantities of airborne uranium hexafluoride (UF6) and its hydrolysis products following a World War II equipment rupture. An excretion pattern for uranium exhibited by these patients is, in light of current knowledge, anomalous. The possible role of pulmonary edema is discussed. Examination of these individuals 38 years later showed no physical changes believed to be related to their uranium exposure and no deposition of uranium could be detected.

Accidents, Occupational↗