[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] 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 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] Carcinogenesis by α-particles has special features due to inhomogeneous tissue irradiation causing focal tissue damage. Focal damage implies a linear relationship between carcinogenesis and dose, but due to the length of an α-track in tissue exceeding cell size linearity doses not necessarily imply malignant transformations as exclusively intracellular processes. Thorotrast is an unsatisfactory model for other α-emitters since in most Thorotrast patients the liver is structurally abnormal as a consequence of tissue damage. Better understanding of the observations on Thorotrast patients require subdivision of patients according to the volume of Thorotrast administered for better defined dose response relationships and experiments to show whether chemical toxicity as well as α-radioactivity contributes to tissue damage

[en] In 187 nonselected patients injected with thorium dioxide, clinical and biochemical studies have been done. The more frequent clinical complaints are related to the gastrointestinal pathology (general dyspeptic complaints such as dyspepsia, nausea, vomiting, pain in the right or left upper abdomen). Thirty-three patients died shortly after the onset of jaundice, ascites, and loss of weight; the clinical diagnosis was liver tumor, and in 15 of these cases with an histological examination, the diagnosis of liver tumor was confirmed (five hemangioendotheliomas, eight cholangiocarcinomas, and two hepatomas). Twenty-five other cases also with histological examination of the liver showed hepatic fibrosis. The biochemical tests disclosed serum dysproteinemia (low albumin and increased α2- and γ-globulin) and increased levels of glutamyltranspeptidase and of alkaline phosphatase, very high indeed in the cases with a liver tumor. The search for α-fetoprotein has been negative in all the 28 cases in which it has been possible to perform this test. A correlation has been found between the length of time elapsed after injection and the incidence of abnormal biochemical findings

[en] 38 postmortem cases and 120 lymph nodes taken from various regions of the body were studied and investigated. The liver and spleen of all the cases and thorotrastomas of six cases were also investigated. All 38 patients had suffered from thorotrastosis and died approximately 28 years after the injection. Paraffin sections, autoradiography, and neutron activation analysis were used. In lymph nodes, the mean concentration of Th-232 is higher than in the liver; it is, however, a little lower than in the spleen. The highest concentration of Th-232 is measured in the lymph nodes of the liver hilus, those in the area behind the pancreas, and around the hilus of the spleen. Lower concentrations are measured in the lymph nodes around the bifurcatio aortae, around the hilus of the lung, and in the groin. The contrast medium is deposited in small concentrations in the sinuses of the lymph nodes without showing any vital reaction in the surrounding area. Th-232 is stored only in a few reticulum cells. The follicles are free of Th-232. In lymph nodes with a higher concentration of Th-232, a strong fibrosis can be seen, occluding the lymph vessels. Spleen and thorotrastomas show a similar fibrosis to that seen in the lymph nodes. A large number of carcinomas and sarcomas of the liver were found. No malignant growth is seen in either lymph nodes, spleen, or thorotrastoma. In the final section of the paper the special localization of tumors in human thorotrastosis is considered

[en] Twenty-four patients followed up by the Portuguese Thorotrast Study Group had liver radioisotopic visualization. A high rate of scans typical of advanced malignancy was found and the authors feel that these patients (knowing they suffer from iatrogenic disease) refuse repeated examinations and laboratory testing, searching medical aid only when malignancy is far advanced. The difficulties of clinical and laboratory follow-up and early liver detection are presented

[en] A brief historical review was made of low-level radiation studies for general populations living around nuclear facilities. In addition, technical and methodological problems were identified and discussed which often arise in all epidemiological studies designed to determine the possible health effects of low-level radiation released from nuclear facilities. Need for extremely large populations for prospective cancer studies was discussed, but accompanying ascertainment difficulties were also emphasized. More epidemiological studies are needed to provide adequate assessment of the potential health hazards of nuclear facilities

[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