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For dose assessment following chronic or accidental inhalation of radioactive aerosols, the dosimetric models of the International Commission on Radiological Protection (ICRP) provide dose coefficients, retention and excretion functions. Unknown date or dates of intake is the major source of uncertainty in dose assessment during routine monitoring of nuclear workers. The two assumptions commonly made in dose assessment from an unknown time pattern of intake have been tested experimentally with a model of repeated inhalation by rats. The hypothetical intake derived from lung measurement was relatively reliable under the two hypotheses. The hypothetical intake derived from excreta measurement depended on the choice of hypothesis and on the real time pattern of intake.

Lors d'une suspicion d'exposition accidentelle aux rayonnements ionisants, la détermination de la dose reçue au moyen de paramètres biologiques est une part importante de la stratégie thérapeutique, en complément des signes cliniques et de la dosimétrie physique. Le dénombrement des aberrations chromosomiques instables dans les lymphocytes du sang périphérique est aujourd'hui la méthode de référence. La préparation des échantillons biologiques dépend cependant du but à atteindre, de l'expertise précise de suspicions d'irradiations ou du tri rapide en cas d'accident de grande envergure. Une adaptation peut être nécessaire s'il s'agit d'irradiation hétérogène ou ancienne. Malgré cette robustesse et ces adaptations, la cytogénétique conventionnelle reste une technique lourde, longue, réservée à du personnel spécialisé. Le dénombrement des micronoyaux dans les lymphocytes binucléés peut constituer une alternative, apparemment plus facile et plus simple que le test des dicentriques. À partir de l'expérience acquise par l'IPSN ces dernières années sur l'expertise des suspicions d'irradiation, ce papier a pour but de dresser un bilan technique quoique succinct de ces différentes approches telles que nous les avons adaptées aux suspicions d'irradiation récente.

The intracellular behaviour of different toxic mineral elements inhaled as soluble aerosols or as insoluble particles was studied in the rat by electron microscopy, electron probe microanalysis, and electron microdiffraction. This study showed that, after inhalation, aerosols of soluble elements like cerous chloride, chromic chloride, uranyl nitrate, and aluminium chloride, are concentrated in the lysosomes of alveolar macrophages and are precipitated in the lysosomes in the form of insoluble phosphate, probably due to the activity of acid phosphatase (intralysosomial enzyme). Also, after inhalation of crystalline particles that are insoluble or poorly soluble in water such as the illites (phyllosilicates), ceric oxides (opaline), and industrial uranium oxides (U3O8), the small crystals are captured by the alveolar macrophage lysosomes and transformed over time into an amorphous form. This structural transformation is associated with changes in the chemical nature of particles inhaled in the oxide form. Microanalysis of amorphous deposits observed after inhalation of uranium or ceric oxides has shown that they contain high concentrations of phosphorus associated with the initial elements cerium and uranium. These different processes tend to limit the diffusion of these toxic elements within the organism, whether they are inhaled in soluble form or not. Microsc. Res. Tech. 36:313–323, 1997. © 1997 Wiley-Liss, Inc.

The intracellular behaviour of different toxic mineral elements inhaled as soluble aerosols or as insoluble particles was studied in the rat by electron microscopy, electron probe microanalysis, and electron microdiffraction. This study showed that, after inhalation, aerosols of soluble elements like cerous chloride, chromic chloride, uranyl nitrate, and aluminium chloride, are concentrated in the lysosomes of alveolar macrophages and are precipitated in the lysosomes in the form of insoluble phosphate, probably due to the activity of acid phosphatase (intralysosomial enzyme). Also, after inhalation of crystalline particles that are insoluble or poorly soluble in water such as the illites (phyllosilicates), ceric oxides (opaline), and industrial uranium oxides (U3O8), the small crystals are captured by the alveolar macrophage lysosomes and transformed over time into an amorphous form. This structural transformation is associated with changes in the chemical nature of particles inhaled in the oxide form. Microanalysis of amorphous deposits observed after inhalation of uranium or ceric oxides has shown that they contain high concentrations of phosphorus associated with the initial elements cerium and uranium. These different processes tend to limit the diffusion of these toxic elements within the organism, whether they are inhaled in soluble form or not. Microsc. Res. Tech. 36:313–323, 1997. © 1997 Wiley‐Liss, Inc.

Le développement en France d'un nouveau procédé d'enrichissement par laser de l'uranium nous a conduits à étudier en situation industrielle les risques radiotoxiques liés à la formation d'un aérosol de type UO2+Umétal. Le but de ce travail est de déterminer pour ce mélange d'oxydes d'uranium les paramètres physico-chimiques et biocinétiques spécifiques à ce composé et nécessaires ultérieurement pour le calcul de dose, ceci en fonction du nouveau modèle pulmonaire décrit par la CIPR 66. Les résultats concernant les mesures de diamètre aérodynamique médian en activité (DAMA) donnent des valeurs comprises entre 5,2 et 10 µm avec jusqu'à 20 % de particules inférieures à 1 µm, tandis que les concentrations au poste de travail varient de 1,8 à 125 Bq m-3et le calcul des périodes biologiques conduit à 48 j pour les tests de dissolution in vitro et à 77 j pour les expériences d'inhalation in vivo, les valeurs de taux de dissolution obtenues permettent d'affirmer que ce composé est de type W suivant la classification de la CIPR 30 et de type M suivant la CIPR 66.

Gametes and embryo tissues are known to represent a sensitive target to environmental toxicants exposure. An alteration in oocyte quality can impact subsequent embryonic development, the establishment and maintenance of pregnancy, foetal developmental competence and even adult disease. The major health concern from DU is mainly centred on its chemotoxic properties as a heavy metal. Although the general toxicity of uranium is well established, little attention was paid to the impact of uranium on reproduction. Some reports in rodents highlighted a negative impact of uranium on male gametogenesis but female gamete quality was scarcely documented. The original purpose of this research was to evaluate the effect of depleted uranium (DU) on mouse oocyte quality after 49 days of chronic contamination in drinking water and to correlate the observed effects with the amount of DU accumulated in organs. Four different DU concentrations were investigated: 0 (control), 10 (DU10), 20 (DU20) and 40mg.L-1 (DU40). DU did not influence the intensity of ovulation but affected oocyte quality. The proportion of healthy oocytes was reduced by half (P<0.001) from 20mg.L-1 compared with control group (0.537; 0.497; 0.282 and 0.239 in control, DU10, DU20 and DU40 groups respectively) whereas no accumulation of DU was recorded in the ovaries whatever the dose tested. Indeed, this study revealed that reproductive tract is not a preferentially reservoir for DU which accumulated mainly in the bone and kidneys. Abnormal perivitelline space (P<0.001) or absence of the 1st polar body (P<0.001) were identified as the main morphological characteristics of DU impact on oocyte. These alterations of mouse oocyte quality could be related to impairment in nuclear or cytoplasmic maturation. The present study showed that oocyte quality was a sensitive target to DU exposure. In the context of this study, the NOAEL for oocyte quality was determined at 10mg U.L-1 in drinking water (1.93mgU.kg-1.day-1). Further investigations are necessary to correlate DU morphological alterations with the subsequent developmental competence of oocyte.

The only treatment proposed after human contamination with MOX (mixed oxide of uranium and plutonium) is diethylenetriaminepentaacetic acid (DTPA), because plutonium is considered to be the major risk. However, both DTPA and uranium are nephrotoxic at high dosages and DTPA has been shown to increase in vitro the cytotoxicity induced by uranium on cultured epithelial tubular cells. This work aimed to test this effect in vivo. Rats were injected with subtoxic (57 �g.kg-1) to toxic (639 �g kg-1) amounts of uranium as nitrate at 0 h, they received two DTPA injections (30 �mol kg-1) at 2 min and 24 h and were euthanased at 48 h. The nephrotoxic effects were evaluated by measurement of the body weight gain, food and water intake, measurement of biochemical parameters in urine and blood, and histological examination of one kidney. The main result was that DTPA did not increase the nephrotoxicity induced by uranium in the range of concentrations tested, which was inconsistent with the in vitro results.

This study was aimed at determining the solubility of two uranium oxides (U3O8 and UO2+Umetal) produced by a new enrichment process using laser technology and at understanding some mechanisms involved in the intercellular particle transformation. The solubility of the two compounds is lower when they have been phagocytised by alveolar macrophages than in a medium without cells. The addition of new macrophages during the culture has permitted the solubility of U3O8 to be tested over 14 days in spite of the toxicity of this compound. The biokinetics of uranium after exposure of rates of UO2+Umetal have confirmed the in vitro results. The electron microscopy study and EELS analysis of alveolar macrophages from rates instilled with both compounds have shown the formation of very thin needles of uranyl phosphate within the lysosomes.