[en] This human investigation of lead absorption from the lungs utilized two forms of lead, lead chloride and lead hydroxide; the former was used in picogram amounts and the latter at microgram levels. These two species of lead were selected in an attempt to simulate the range of physicochemical properties found in atmospheric lead (urban air). Aerosols labeled with lead-203 were made of comparable aerodynamic size by using sodium chloride as the deposition-determining aerosol. After brief, mouthpiece exposures, 17 subjects were followed by serial counting with a thoracic array of scintillation detectors and two leg counters. Serial blood samples were also taken. The two exposure groups showed similar total deposition values (23 vs 26%) and the same biological retention halftimes, viz., 22.6 hr. When the retention data were corrected for blood-borne ²⁰³Pb, the biological halftimes for lung lead retention averaged 13.1 and 14.2 hr, respectively, and were not significantly different. The collective evidence supports the view that atmospheric lead is rapidly and completely absorbed from the human lungs

[en] The kinetics of whole body lead elimination and organ distribution were studied in 10-day-old and adult female mice following a single dose of lead. Necropsies were performed periodically during the 50-day experiment to assess organ lead distributions and lead elimination. Between Days 15 and 50 excretion of lead was found to occur nearly equally through urinary and fecal routes. Whole body lead retention during the terminal elimination phase was observed to have a half-time simular to that of lead retained in femur. Rates of lead elimination from femur and from whole body of young mice were apparently less rapid than comparable elimination rates in adult mice. Lead fluxes from the brains of young and adult mice were closely approximated by single component exponential equations. The results suggest that a three-compartment model does not adequately account for the kinetics of lead distribution and retention in mouse brain after a single dose

[en] The ²³⁸Pu concentrations of varous tissues were measured for seven species of freshwater fish from an ecosystem containing elevated levels of ²³⁸Pu. The highest levels of ²³⁸Pu were found in the gastrointestinal tracts and gills, while the lowest levels were found in muscle tissue. A rapid uptake of ²³⁸Pu was observed for hatchery bluegills introduced into this system. High plutonium concentrations in the gastrointestinal tracts and gills suggest that these organs are potential uptake sites. The presence of ²³⁸Pu in certain tissues (liver, gonads, bone, and muscle) indicates that there is a translocation of ²³⁸Pu from the uptake sites

[en] The causes of death of 144 Japanese autopsy cases during 1945-1975, who had been intravascularly injected with Thorotrast in life, were compared with those of non-Thorotrast-administered autopsy cases in the same age bracket, recorded in the Annals of Japanese Pathological Autopsy Cases during 1958-1973. This comparison revealed that the incidence of malignant hepatic tumors was more than 10 times higher in the Thorotrast-administered cases. The increase was attributable to an increased incidence of hemangioendothelioma and cholangiocarcinoma of the liver. The only significant increase of liver cirrhosis found to exist in the Thorotrast group occurred in the female cases. Some of the Thorotrast-administered cases were found to have developed myeloid leukemia and erythroleukemia. There was also a significant increase in the number of cases of aplastic anemia in the Thorotrast group, but clinically and pathologically these were atypical. Lymphatic leukemia was not observed. No significant difference was found in the incidence of either malignant lymphomas or osteosarcomas in the Thorotrast group and the controls. Lung cancer, on the other hand, showed a significantly higher incidence among the controls than among the Thorotrast-administered cases

[en] Chronic irradiation from thorium dioxide (Thorotrast) induces chromosome abnormalities in individuals subjected to systemic injection as well as for those injected for perinasal sinuses visualization. Although considered without harmful effects owing to the small volume used and the surgical care of clearing the cavities, enough Thorotrast could have been absorbed and entered into the blood circulation to be taken in by the lymph node system in this last group of patients in order to yield a significant number of abnormal cells with chromosome aberrations of 5.34%

[en] A histological review of 25 cases of Thorotrast-induced angiosarcoma revealed characteristic antecedent or precursor changes which are similar to previously described changes present in hepatic angiosarcoma secondary to vinyl chloride, arsenicals, or of unknown etiology. The antecedent or precursor change consists of areas with simultaneous activation of both the hepatocytes and sinusoidal cells and associated lesions in the sinusoidal and perisinusoidal spaces. The hepatic cell plates surrounding these areas are compressed with subsequent development of fibrous septa at the interface between the areas of mixed hyperplasia and the areas of compression. In these multiple areas multicentric angiosarcomas develop in close approximation to the portal tracts but not to the Thorotrast deposits

[en] After administration of polychlorinated biphenly (PCB) at 0.055 (w/w) of the diet to Wistar rats for 30 days, followed by intraperitioneal injection of tritiated water, [¹⁴C]mevalonate, and [¹⁴C]acetate, there was a decrease in cholesterol biosynthesis in rat liver. No significant change in cholesterol formation was observed when PCB was administered at 0.01% (w/w) of the diet. In vitro inhibition of cholesterol synthesis by rat liver microsomes was observed with PCB. Squalene 2,3-oxidocyclase activity of rat liver microsomes was not significantly altered. Desmosterol delta²⁴ reductase activity was inhibited only at relatively high concentrations of PCB. There was increased incorporation of radioactivity into squalene and lanosterol, in vitro, in the presence of PCB. The primary inhibition of cholesterol biosynthesis appears to be at the demethylation and rearrangement reactions between lanosterol and cholesterol in the biosynthetic pathway

[en] With the publication of the latest recommendations of the International Commission on Radiological Protection, several new issues have arisen. The Commission arrives at its recommendations for dose limits using a theoretical or predictive method making use of the data on risks of cancer in populations who have been accidentally or iatrogenically exposed. The issues of importance in this method are discussed, particularly the concept of acceptable risk. An aternative method for setting dose limits, a pragmatic method, involves the study of the cancer incidence in radiation workers and a comparison with cancer incidence in other occupations and industries

[en] The authors present a case of a woman injected with thorium dioxide in 1942, who 35 years later developed clinical, laboratory, scintigraphic, and echographic data very suggestive of liver tumor, as has been described in patients injected with thorium dioxide. However, in this case the patient recovered subjectively and objectively, after symptomatic therapy. This is unusual in the evolution of those patients, as our group had shown in other papers

[en] In Thorotrast patients, chromosome aberrations of lymphocytes from peripheral blood are to be used as a biological dosimeter. To get a significant dose-effect relationship it is necessary to estimate the absorbed dose of a single lymphocyte during its exposure time. In individual cases only average values can be calculated, based on assumptions of special distributions of Thorotrast. At first effects of the size of Thorotrast conglomerates and of their space distribution on the α-radiation dose distribution in their surroundings are described in a model. Then this model is transferred to the real dimensions and the histological structures of lymph nodes bearing Thorotrast. In some individual cases the microdistribution of Thorotrast has been determined in lymph nodes. Some of these results are demonstrated. According to these Thorotrast distributions, calculation of real absorbed dose of lymphocytes are performed. These values can be used for setting up a dose-effect relationship for biological dosimetry