Characterisation and dissolution of depleted uranium aerosols produced during impacts of kinetic energy penetrators against a tank.

Aerosols produced during impacts of depleted uranium (DU) penetrators against the glacis (sloping armour) and the turret of a tank were sampled. The concentration and size distribution were determined. Activity median aerodynamic diameters were 1 microm (geometric standard deviation, sigma(g) = 3.7) and 2 microm (sigma(g) = 2.5), respectively, for glacis and turret. The mean air concentration was 120 Bq m(-3), i.e. 8.5 mg m(-3) of DU. Filters analysed by scanning electron microscopy (SEM) and X ray diffraction showed two types of particles (fine particles and large molten particles) composed mainly of a mixture of uranium and aluminium. The uranium oxides were mostly U3O8, UO2.25 and probably UO3.01 and a mixed compound of U and Al. The kinetics of dissolution in three media (HCO3-, HCl and Gamble's solution) were determined using in-vitro tests. The slow dissolution rates were respectively slow, and intermediate between slow and moderate, and the rapid dissolution fractions were mostly intermediate between moderate and fast. According to the in-vitro results for Gamble's solution, and based on a hypothetical single acute inhalation of 90 Bq, effective doses integrated up to 1 y after incorporation were 0.54 and 0.56 mSv, respectively, for aerosols from glacis and turret. In comparison, the ICRP limits are 20 mSv y(-1) for workers and 1 mSv y(-1) for members of the public. A kidney concentration of approximately 0.1 microg U g(-1) was predicted and should not, in this case, lead to kidney damage.

[Methods to measure the cutaneous transfer of radionuclides across the intact or lesioned epidermis, application to radiotoxicology]. / Méthodes de mesure du transfert cutané des radionucléides au travers d'un épiderme intact ou lésé, application à la radiotoxicologie.

Although skin contamination by radionuclides is the most common cause of nuclear workers accidents, few studies dealing with the penetration of radioactive contamination through the skin are available. This work is a review of experimental methods that allow to assess transfer of radionuclides through the skin in occupational conditions, with or without skin trauma. The first section describes the different methods applied for skin transfer assessment of chemicals used in pharmacology. Major radionuclide contamination accidents can be associated with skin traumas. Thus, the second section describes the adaptation of these methods to radiotoxicology. Finally, the third section is an in vivo investigation of cobalt transfer (57CoCl2) through undamaged and damaged skin which simulates different industrial accident conditions (excoriation, acid or alcalin burn, scalding, branding).

Contamination and decontamination of rat and human skin with plutonium and uranium, studied with a Franz's chamber.

PURPOSE: Our work offers a new method of assessing human skin radiocontamination and of appraising its treatment. This in vitro technique stems from methods used in skin pharmacology. MATERIALS AND METHODS: Franz's diffusion chambers, which help maintain the physiological condition of a skin biopsy, are used to study how 233U and 239Pu, added to a 0.1 N solution of nitric acid, could enter skin. The efficiencies of two different decontaminating agents (Na3Ca)DTPA (25%) and EHBP (0.5 M) are compared. These studies were made on human skin samples, recovered after plastic surgery. Parallel experiments were carried out on hairless rat skin biopsies and on the skin of live hairless rats. RESULTS: Results in vivo and in vitro on the rat were not significantly different which validates the in vitro technique. In human beings, most of the radioactivity was found in the epidermis, with 2-4% found at the level of the dermis. By means of autoradiography we were able to identify that this radioactivity was concentrated in and around hair and sebaceous glands. Local treatments by EHBP seemed more efficient than those by DTPA in decorporating uranium and plutonium but the complexes radionuclide-EHBP seemed to diffuse through the skin more than the radionuclide-DTPA complexes if the skin was not rinsed after application of the chelating agent. CONCLUSION: This new in vitro technique using human skin has been validated for radiotoxicology. It can be used to quantify the diffusion of radionuclides through the various skin layers and to assess the efficiency of decontaminating agents.

[Efficiency of etidronic acid in the case of cutaneous radiocontamination by actinid elements: in vitro evaluation]. / Efficacité de l'acide étidronique dans les radiocontaminations cutanées par les actinides: évaluation in vitro.

Ethane 1 hydroxy 1.1. biphosphonate (EHBP) is a medicine named Didronel, which inhibits bone resorption in the case of Paget's disease. This molecule could offer a new application in radiotoxicology. Our works describe its efficiency as decontaminating agent in uranium and plutonium cutaneous radiocontamination. Its effect on uranium and plutonium is demonstrated by two in vitro techniques using human cutaneous explants. Both techniques are usually used in dermopharmacology to estimate the action of topic drugs.

[Percutaneous absorption of metallic cations: uranium particulates]. / Absorption percutanée des cations métalliques: particularités de l'uranium.

Washing is usually used to reduce the risk of a skin contamination. Skin biopsies were used and contaminations were realised with 1) soluble radioactive calcium 2) insoluble particles of uranium. The result obtained with different wash liquids are presented here. Water and soap had no effect but hypertonic DTPA was the better therapy to remove uranium from skin.

[Reduction of renal uranium uptake by acetazolamide: the importance of urinary elimination of bicarbonate]. / Réduction de la fixation rénale de l'uranium par l'acétazolamide: importance de l'élimination urinaire du bicarbonate.

Acetazolamide was compared with bicarbonate for the treatment of contamination with uranium. Uranium was injected peritoneally in rats, and its distribution was investigated. Acetazolamide was three times more efficient than bicarbonate in reducing the renal content of uranium. On the other hand, it had no effect on hepatic or skeletal content. In this study, renal physiology provides the basis for understanding the mode of action of acetazolamide and bicarbonate. In this context, it is of interest to determine the alkalinity of the urine, with the aim of knowing whether bicarbonate is present to mobilize uranium.

[Thorium a radioactive element in current use: physical-chemical properties and biological processing]. / Le thorium, un radioélément d'actualité: propriétés physico-chimiques et devenir biologique.

The radioactive properties and physicochemistry of thorium were studied and correlations drawn between thorium and element sof the titanium group, lanthanides and plutonium. It appears that the behavior of Th4+ and Pu4+ are similar, particularly their distribution pattern on bone surfaces. Chelating agents are reviewed and the structure of metal chelates indicated.

[Thorium: analysis and dosimetry of thorium welding electrodes]. / Le thorium: analyse et dosimétrie des électrodes de soudures thoriées.

The use of thoriated tungsten electrodes may be at the origin of a potential hazard for the personnel involved in the use of electrodes, as well as the general population. To assess this hazard, the electrode radioactivity measurements by alpha and beta counting has been conducted. The radioelements were identified by alpha and gamma spectromety. It appeared that there was a radioactive disequilibrium between thorium-232 (Th-232) and it daughters atoms. Additionally, some thorium 230 (Th-230) belonging to the uranium chain, was present. The chemical separation and the milling processing had affected the radioactive composition and the thorium in the electrodes, doesn't exactly corresponds to natural thorium. Radiation doses were also assessed: film and photoluminescence dosimetry were undertaken. Finally smears method showed a alpha removable area contamination. Even if the hazard is weak. As a matter of fact, it must not be neglected because it was complex, for the thorium was always accompanied by Th-232 progeny, alpha emitters but also beta and gamma emitters.

[Modeling of cutaneous radio-contamination: effects of washings by soap and by solutions of DTPA]. / Modélisation des radiocontaminations cutanées: effets de lavages par le savon et par les solutions de DTPA.

Some neutral chirurgical soap, a solution of diethylen penta acetic acid (DTPA) at 1% and a solution at 25% of monocalcic trisodium salt of DTPA in serum have been studied on models of cutaneous contamination. Cesium 137 (137Cs) and Plutonium 239 (239Pu) have been used for the contamination. This research gives a protocol for external cutaneous decontamination which could be used in reception units for radiocontaminated wounded. Even the radioelement is unknown, DTPA at 25% represents a good solution for the treatment of general contamination, which is not the case for DTPA at 1%. A soap in which DTPA at 1% has been added is adapted for large cutaneous contamination. The treatment of ocular contamination is also studied in this article.

Topological structure activity analysis of diphosphonates in the elimination of radionuclides from body.

The effectiveness of a series of diphosphonates in the elimination of radionuclides from rat was analyzed by means of topological structure and activity relations. It is possible to compute some numbers or indexes characteristic of the topological structure of a molecule. The Wiener Index which measures the ramification of a molecule has been chosen. An attempt was made to correlate the effectiveness of the molecules tested in removing plutonium from the organism to their Wiener Index. Only unprotected molecules i.e in free acidic form fitted the correlation. LICAM (C) and DTPA were used as reference molecules to control these results. The fact that LICAM (C) well fitted the relation and that DTPA did not are discussed, as are some general requirements for a new molecule to be effective.

Modulation of leucocyte activation in the early phase of the rabbit burn injury.

Previous studies in burned patients have shown an early enhanced polymorphonuclear leucocyte (PMN) generating capacity for superoxide radical (O2.-), for the arachidonic acid (AA) lipoxygenase metabolite leukotriene B4 (LTB4) and for platelet activating factor-acether (PAF). These findings have been confirmed on a burn injury rabbit model. As we have suggested a pivotal role for an exaggerated initial (less than 36-48 h) neutrophil stimulation leading to a later (greater than 72 h) immuno-depression and anergy, we tried to modulate the early phase by drug therapy. A Ginkgo biloba extract (IPS200) injected i.v. in burned rabbits greatly reduced O2.- and LTB4 generation on A23187 challenge. IPS200 includes flavonoids and other polyphenols, inhibiting either arachidonic acid metabolism or PAF receptors, and may thus exert their modulating effect on PMN function in thermal injury.

Biological behaviour of Pu administered to animals as Pu-standard LICAM(C) complex: therapeutical attempts to decrease Pu kidney burden.

The biological fate of plutonium (Pu) introduced as a Pu-standard LICAM(C) complex was investigated in male rats of two strains, in male and female mice and in the baboon. We observed that, whatever the animal species or the entry route, this complex was deposited rapidly in the kidney. In addition, more of the complex accumulated in the rat (16% of injected radioactivity) than in either the mouse (7%) or baboon (5%). This Pu deposit was cleared spontaneously with a half-life of 10 days in the rat and only 5 days in the mouse. We noted that the complex was deposited on bone during this period and that, 10 days after the introduction of Pu, the skeleton became the main organ of retention of Pu (7% of the dose in the rat, 4% in mice and 3% in the baboon). In spite of this, which would indicate that Pu-standard LICAM(C) resembles a weak complex, gut transfer was comparable with that of a strong complex 1.10(-3) (f1 = 1.10(-3)). Pu deposit seemed to be pH dependent and could be modified be varying the pH balance of urine. Bicarbonate was among the most effective of the different drugs used to affect this balance, as 5 h of continuous perfusion decreased the kidney Pu burden by a factor of 4. Such efficacy was also observed with diethylenetriaminepenta-acetic acid (DTPA) perfusion. The pragmatic consequence of these experiments is the recommendation of mixed therapy: standard LICAM(C) plus bicarbonate or DTPA.

[Effect of irradiation on the in vivo and in vitro subcellular distribution of radiostrontium in rat liver]. / Effet de l'irradiation sur la distribution subcellulaire du radiostrontium dans le foie de rat in vivo et in vitro.

Hepatic mitochondrial strontium uptake is enhanced in whole body irradiated rats. Effect is observed on animals but not on irradiated organ slices. It is likely that a hypophyso - adrenal axis hormone plays a role in changes observed in vivo.

Titration of total binding sites for growth hormone in rabbit liver. Quantitative modifications of these sites during pregnancy.

The present work outlines various kinetic parameters of the interaction between bGH (bovine growth hormone) and a receptor located on the membranes of rabbit liver. A dissociation procedure, which strips the hormone off its receptor has been worked out, by varying MgCl2 concentrations and times of contact; exposure to 4 M MgCl2 for 15--30 min was found optimal for dissociation, without denaturing the receptor, as shown by the possibility of rebinding the hormone to the desaturated membranes. This method has been applied to titrate growth hormone receptors in rabbit liver, during pregnancy and lactation. The first half of pregnancy is characterized by a gradual increase of receptor levels and low saturation by endogenous hormone; conversely at parturition, there occurs a striking increase in receptors, which, however, may be demonstrated only after desaturation. During the lactational period, the receptors reamin in part saturated. The results suggest that growth hormone levels increase at parturition and during lactation in the rabbit and hence may play an important role during lactation. The factors which modulate receptor levels at the same period remain unknown.