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An overview is given over the use of generic and site-specific information on natural geochemical fluxes and resulting concentrations in various compartments in the geosphere and surface environment for the evaluation of the possible role of a geological nuclear waste repository as a component participating in natural geochemical cycles. Use is made of information from geochemical prospecting, geochemical mapping, weathering and river catchment studies as well as case studies at natural anomalies. Following the more globally orientated prestudy an overview is given over the compilation of a generic and site-specific geochemical flux and concentration data base of selected elements in Finland for use as complementary safety indicators to be compared with calculated repository releases. In the data base site-specific data is given for the Palmottu natural analogue site (U mineralization) and four repository investigation sites. Specific geological, hydrogeological, geochemical, topographical and climatic features of the glaciated terrain in Finland are the main reason that geochemical fluxes are mostly limited to the surface environment and influences mediated by groundwater transport from the depth are difficult to identify. The methodology of the use of natural safety indicators has some potential for improvement. The importance of the geochemistry of the groundwater-rock system and the elements, in particular, in the site-specific data on U fluxes became evident. A deeper understanding of the driving forces, transport mechanisms and parameters and relevant spatial and time scales behind natural geochemical cycles in differentgeological settings is needed to enable a validating evaluation of the suitability of concepts of chemical stability and radionuclide migration, scenarios such as glacial cycles and models of coupled chemical transport and could allow confidence building into the repository safety case by evaluating uncertainties and conservativeness using complementary modelling and multiple lines of reasoning. Observations in nature comprising groundwater-mineral interactions and U mobilization and fixation could be confirmed by reactive coupled chemical transport modelling. The relevant time scales behind the transport processes could be defined by dating and preliminary conclusions were achieved concerning glacial meltwater intrusion as the triggering mechanism. The transferability of this geo-information to a larger regional scale and in the time scale was confirmed. Some additional dating and analytical data on the Palmottu water-rock system and comparable sites is still necessary. Pretests for the application of advanced concepts and modelling tools at the repository site Olkiluoto were initiated in order to improve the regulator’s capability to evaluate a safety case focussing on geochemical stability and radionuclide migration issues.

A boulder sample was studied for its unusual U content. Analyses of U-series nuclides within the rock matrix perpendicular to an assumed fracture face show abrupt pulse-like concentration distributions with very low concentrations of U daughters. Both Th-230/U-234 and Pa-231/U-235 activity ratios are low, indicating recent U accumulation into the rock. Matrix diffusion is tested as a possible cause for the experimental observations. We assume that the diffusion process was triggered and controlled by rock expansion, strong mixing of different water types and rapid land uplift at the end phase of the last glaciation.

If Hypoparathyroidism develops after thyroidectomy, it commonly becomes manifest during the first few weeks. It is most unusual for the disorder to occur almost thirty years following such an operation, as seems to be true in the case presented here.

T HE development of a commercially practical method for synthesizing thyroxine,’ the identification of 3,5,3’-L-triiodothyronine in human plasma2 and the recognition of its physiologic importance 3,4 have stimulated considerable interest in the re-evaluation of thyroid hormone therapy. Several reports have already appeared describing the oral or intravenous use of sodium L-thyroxine,617 L-triiodothyroninell1a,16--20 and D,L-triiodothyronine16*17 in patients with myxedema. That desiccated thyroid substance, thyroxine and triiodothyronine are all hormonally active in such trials is universally agreed. However, reported investigations with the best human test subject, the myxedematous patient, are not yet of sufficient number to settle completely the relative intensity, speed and duration of action, as well as the variations in responsiveness. The present report deals with experiences with twelve patients suffering from adult myxedema. The manner of approach differs in one respect from most if not all of the other studies of human subjects. In the present work, following attainment of a euthyroid state under therapy, the patient has been allowed to lapse into a measurable degree of hypothyroidism prior to the beginning of therapy with the same or a second thyroid preparation. This has afforded us repeated comparisons under conditions as nearly identical as possible for us to achieve. average age of fifty-three and a half years, were the subjects of this study. Each had the classical symptoms and signs of myxedema. The diagnosis was further confirmed by determination of the basal metabolic rate, serum cholesterol and, in some instances, the serum protein-bound iodine, thyroidal uptake of radioactive iodine and the twenty-four hour excretion of creatine of a person on a meat-free diet. Manifestations of myxedema had been present for periods varying from six months to twelve years prior to recognition, with an average duration of 3.7 years. In seven subjects the development of myxedema was spontaneous; in three it followed thyroidectomy; in one radiation therapy, and in the remaining one the prolonged use of an antithyroid compound. The initial basal metabolic rates of the group ranged from minus 16 to minus 47 per cent, with an average of minus 34.9 per cent. Serum cholesterol values, performed by the method of Pearson, Stern and McGavack,23 varied from 291 to 443 mg. per 100 cc. with an average of 358.4 mg. per 100 cc. The serum protein-bound iodine, carried out by the method of O’Neal and Simmsz4 was initially 3.9 pg. per 100 cc. or less. Because of the changes initially present, serial determinations were made throughout the study, as well as repeated estimations of the urinary 17-ketosteroids, blood counts, electrocardiograms and cardiac roentgenograms.

Although Lawson, Rimington and Searle (1) synthesized and showed the action of 1-methyl-2-carbethoxy-thio-imidazole (carbimazole) in rats and man in 1951 and found it to be slightly more potent than methimazole in inhibiting the thyroidal uptake of I131 in both rats and man, there have been remarkably few further reports of its activity to date (2–13). These cover clinical data for somewhat less than 500 patients. Moreover, two studies (8, 11) have been concerned solely with the recording of a single case of toxicity, presumably due to the drug. As a general rule, the rightful place of an antithyroid compound in the treatment of hyperthyroidism can rarely be settled until data from several thousand cases are critically analyzed. This seems to be particularly true for determining toxicity, and toxicity in relation to daily dose and duration of treatment. For these reasons, we are prompted to add a small series of cases to those already in the literature.