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PubMed2004

Chemical speciation of thorium in marine biogenic particulate matter.

Concentrations of particulate thorium in seawater were determined together with the strong organic ligand (SOL) and uranium in particulate matter (PM). The concentrations of particulate Th in surface waters of the western North Pacific and the Sea of Japan ranged from 0.05 to 1.5 pM (1 x 10(-12) M), and showed relatively large temporal and spatial variations. In order to chemically characterize the particulate Th in seawater, the relationship between particulate Th and SOL concentrations in surface PM was examined. The result reveals that particulate Th in surface PM was well correlated with the SOL concentration in PM. The concentrations of particulate Th in surface water were linearly related to those of particulate U. Mass balance analysis suggests that the dominant chemical form of Th(IV), as well as of U, in surface PM is a surface complex with the SOL in PM. Our findings suggest that the SOL in PM is a nonmetal-specific chelator originating from the cell surface of microorganisms.

Particle Size↗
PubMed1982

A long-term hypopigmentary effect of thorium-X on freckled skin.

Sixteen years ago, an area on the forearm of a freckled subject was painted with a solution containing 500 esu of thorium-X per ml. Since then, despite much exposure to solar irradiation, there has been a complete absence of freckles from this area, which stands out in marked contrast to the surrounding skin. Biopsy of the skin from the area was examined by the Dopa technique and by electron microscopy. Melanocytes are present in apparently normal numbers, but in a condition of almost complete inactivity. This depression of melanogenesis is difficult to account for either on the basis of an environmental effect, or of intracellular inhibitory mechanisms.

Humans↗
PubMed2003

Raman scattering investigations of nanocrystalline thorium oxide.

Raman scattering investigations are carried out on nanocrystalline thorium oxide powders. Shift and broadening of the Raman peak associated with F2g phonons are observed for the nanocrystalline samples as compared with those of the bulk. The peak shift and broadening are found to increase further as the particle size decreases. A quantitative analysis of the Raman line shape is carried out with a Gaussian confinement model, and the estimated size is found to be consistent with that obtained from X-ray diffraction and transmission electron microscopy.

Crystallization↗
PubMedDate not supplied

Thorotrast (thorium dioxide) granuloma of the neck: Surgical considerations.

Summary--Thorotrast (thorium dioxide) is a contrast material which was first used for angiography about 40 years ago. Its use was discontinued because of the reported incidences of malignancy following injection. Its long-term effects are related to its long half-life and slow excretion rate. Following extravasation into the soft tissues of the neck, the prolonged radiation effect results in tissue breakdown with formation of granulomas. There can also be cranial nerve palsies, occlusion of the major blood channels, laryngeal edema, pharyngeal and esophageal ulceration, and fistula formation. To avoid these late consequences, it is suggested that Thorotrast granuloma in the neck be excised radically. Partial or limited resections are inadequate.

Angiography↗
PubMed1990

Health effects of a thorium waste disposal site.

A case-control study of 112 households residing in the vicinity of a thorium waste disposal site found a higher prevalence of birth defects (RR 2.1) and liver diseases (RR 2.3) among exposed than the unexposed group. The numbers were quite small and the confidence intervals wide, however, so that no definite conclusions can be drawn from these data.

Adolescent↗
PubMedDate not supplied

Uptake rates of thorium progeny in a semiarid environment.

The release rates and transformation processes that influence the mobility, biological uptake, and transfer of radionuclides are essential to the assessment of the health effects in the food chain and ecosystem. This study examined concentrations of 222Th in both soil and vegetation at a closed military training site, Kirtland Air Force Base (KAFB), New Mexico. Brazilian sludge was intentionally introduced into the topsoil in the early 1960s to simulate nuclear weapon accidents. Soil (60) and vegetation (120) samples were collected from 1996 to 2000 and analyzed for radionuclides and progeny. High-resolution gamma-ray spectroscopy was used to determine radionuclide activities. The results indicate that the thorium progeny were the predominant contaminant in soil and vegetation. Concentration ratios (CRs) were calculated based on actinium levels.

Desert Climate↗
PubMed1992

Mortality among workers in a thorium-processing plant--a second follow-up.

A second follow-up of mortality was carried out for workers employed in a thorium-processing plant between 1915 and 1973. The study group comprised 3796 workers (3119 men and 677 women). Of the whole group, 926 (761 men and 165 women) were deceased and 2620 (2161 men and 459 women) were still alive, while 250 (6.6%) were lost to follow-up. For the male workers, the standardized mortality ratio (SMR) for all causes of death was 1.12 with a 95% confidence interval (95% CI) of 1.05-1.21. The SMR for the male workers was also significantly increased for all cancers (SMR 1.23, 95% CI 1.04-1.43) and lung cancer (SMR 1.36, 95% CI 1.02-1.78). For the female workers, the SMR was 0.74 (95% CI 0.63-0.86) for all causes and 0.53 (95% CI 0.35-0.78) for all cancers. The results of a Poisson regression analysis showed that there was no significant effect of the selected factors on lung cancer mortality.

Cause of Death↗
PubMed2000

Concentrations and consequent radiation doses of uranium-238, thorium-232 and potassium-40 contained in the front glass of CRTs.

Concentrations of 238U, 232Th, and 40K contained in the front glass of CRTs (cathode ray tube) of three television sets are measured by gamma-ray spectrometry on the assumption of radioactive equilibrium in uranium and thorium series. The concentrations of 238U and 232Th are also measured by neutron activation analysis. The obtained results by the two different methods agree well within experimental uncertainty, showing that the radioactive equilibrium is found to be established in the present samples, and that the concentrations of 238U and 232Th in the glass can be measured by the gamma-ray spectrometry as well as by the neutron activation analysis. We also found that although the obtained concentrations of 238U (6.5-13.5 ppm in weight) and 232Th (8.4-15.1 ppm) vary considerably between these three kinds of CRTs, those of 40K (average: 7.45 +/- 0.05 ppm) are almost equal for all samples. Moreover, the radiation dose rates are estimated for gamma-rays from the CRT. At distances larger than 30 cm from the surface of the front glass, even the dose rate (5.65 x 10(-3) microSv/h) for the CRT containing the highest concentration of 238U and 232Th is smaller than one-tenth of that (7 x 10(-2) microSv/h) for background radiation, and that is practically negligible.

Background Radiation↗
PubMed1975

Uptake of colloidal thorium dioxide by the mouse connective tissue mast cell.

The ability of the mouse mast cell to phagocytize colloidal thorium dioxide, Thorotrast, was investigated employing the mouse connective tissue air pouch. The connective tissue mast cell of mouse was found to have limited capability to ingest the particulate Thorotrast in comparison to the rat peritoneal mast cell which ingested this material readily. Fibroblasts and macrophages in the connective tissue removed injected Thorotrast very rapidly in contrast to mast cells that demonstrated limited phagocytic capabilities. The tissue mast cell of the mouse, therefore, should not be considered a part of the reticuloendothelial system.

Animals↗
PubMed2001

[Spectrophotometric determination of microamounts of thorium with 3,5-dibromosalicylfluorone by ion-exchange separation].

A method for the determination of Thorium reacting with 3,5-dibromosalicylfluorone, cetyltrimethylammonium bromide and EDTA is proposed. This method is based on the formation of a red-violet colored multicomponent complex in pH 8.8-10.2. The complex has an absorption maximum at 557 nm and its molar absorptivity is 2.19 x 10(5) L.mol-1.cm-1. The Beer Law is obeyed in the concentration range of 0-7 micrograms.25 mL-1 for Th(i.v.). The composition of Th to 3,5-DBSF in the complex is 1:4. All interfering ions may be removed by eluting with 6 mol.L-1 HCl through cation-exchange resin. This method has been used for the determination of Th in Rare-Earth sample ores by ion-exchange separation.

Bromobenzoates↗
PubMed2005

[Results of peripheral blood tests in thorium production workers].

The authors studied peripheral blood parameters in thorium production workers. Separate analysis covered a group of subjects with chronic radiation sickness. Reliably more pronounced in the chronic radiation sickness group, disposition to thrombocytopenia and leucopenia could be caused by occupational factors. Anemia associated with disposition to erythrocytopenia and increased ESR could be caused by malnutrition.

Chemical Industry↗
PubMed1978

[Thorium-induced neoplasia of the spleen? (author's transl)].

A patient is presented in whom multiple lienal circular foci are seen 25 years after application of a thorium-containing contrast medium for vascular visualization, over and above the well-known characteristic ThO2 deposits in the liver and spleen. The article discusses the problem whether these circular foci which meet the angiographic criteria of an angioblastic sarcoma, should be considered as a thiorium-induced neoplasia.

Angiography↗
PubMed1980

[Radiological signs of a disease that is dying out: hepato-splenic atrophy and cholangiocarcinoma after administration of thorium dioxide (Thorotrast)].

The cases of two patients with radio-opaque residues of contrast medium (Thorotrast) in the abdomen, at the level of the liver, the spleen and certain lymph node groups of the hepatic hilum and the pancreas are reported. In one of the two patients (both of whom had undergone examination with this contrast medium in the '40s) necropsy showed the existence of cholangiocarcinoma. It is therefore considered useful to recall the X-ray signs typical of this pathology, which is dying out after the abandonment of thorium dioxide as an X-ray contrast medium.

Adenoma, Bile Duct↗
PubMed1983

Endothelial cell origin of thorium oxide-induced angiosarcoma of liver.

A 72-year-old woman was found at autopsy to have hepatic angiosarcoma approximately 30 years after systemic thorium oxide (Thorotrast) injection. Intracytoplasmic localization of factor VIII-related antigen was demonstrated by an immunoperoxidase method, confirming the endothelial cell origin of the tumor.

Aged↗
PubMed1997

Cumulative genetic damage in hematopoietic stem cells in a patient with a 40-year exposure to alpha particles emitted by thorium dioxide.

Thorotrast, a colloidal suspension of the long-lived radionuclide, thorium-232, was widely used as a radiographic contrast medium for several decades. Due to the poor excretion of the sol, however, Thorotrast would deposit in the liver, bone marrow and other tissue, and patients would receive alpha-particle irradiation for life. To gauge the cumulative genetic damage to hematopoietic stem cells due to chronic exposure to alpha particles, we conducted a multi-end-point evaluation in a 72-year-old man who had been administered a 32-ml bolus of Thorotrast during cerebral angiography performed over 40 years ago in 1950. Peripheral T lymphocytes were cultured to quantify the frequencies and cellular distributions of asymmetrical and symmetrical types of chromosome aberrations in first-division metaphases and micronuclei in cytokinesis-arrested interphase II cells. Aberrations were scored using classical chromosome group analysis methods and chromosome painting techniques. Assays of glycophorin-A (GPA) mutations in red blood cells were also performed to obtain a relative measurement of damage sustained by the erythroid stem cell population. Results revealed that approximately 30% of the lymphocytes in this patient contained one or more chromosome aberrations, the majority of which were of the "stable" type. About one-third of the lymphocytes with chromosome damage carried multiple aberrations, suggesting that significant numbers of stem cells survive exposures to alpha-particle radiation that induce complex genomic alterations. Increased frequencies of GPA mutations were observed, demonstrating that genomic damage is also induced in erythroid progenitors. The numbers of micronuclei in lymphocytes were only moderately increased compared to expected values for persons of comparable age, and thus this end point was not useful for quantifying exposure level. Despite the relatively severe burden of somatic cell damage induced by 40 years of internal alpha-particle irradiation, the patient remains surprisingly free of any serious illness.

Alpha Particles↗
PubMed2003

Determination of thorium and light rare-earth elements in soil water and its high molecular mass organic fractions by inductively coupled plasma mass spectrometry and on-line-coupled size-exclusion chromatography.

Inductively coupled plasma mass spectrometry (ICP-MS) has been used for the determination of thorium and light rare-earth elements (LREEs) in soil and soil water samples from a mineral deposit (Morro do Ferro, Minas Gerais, Brazil). Size-exclusion chromatography (SEC) on-line coupled to ICP-MS and UV-detection was applied to verify possible association/complexation of these elements with organic matter in soil water separated by a centrifugation technique. Concentrations of DOC in soil waters are in the range of 10 to 500 mg L(-1) and correlate with the organic carbon content of the soil (r=0.950; p<0.001). Concentrations of 30 to 40 microg L(-1) for the LREEs (La, Ce, Nd) and up to 14 microg L(-1) for Th were measured in soil waters of highest DOC content. SEC chromatograms of these waters showed the association of elements with different nominal high-molecular-mass ranges, characteristic of soil humic and fulvic acids: >10,000 Da, with a retention time of about 10 min; 7000 to 8000 Da with retention times of 13 to 15 min; and 2000 to 4000 Da with retention times around 23 min. Elemental peaks associated with dissolved organic matter below 1000 Da were not observed, suggesting that complexation with simple plant organic acids or inorganic ligands is of minor importance in the environment studied in this work.

Journal Article↗