Properties, use and health effects of depleted uranium (DU): a general overview.

Abstract Depleted uranium (DU), a waste product of uranium enrichment, has several civilian and military applications. It was used as armor-piercing ammunition in international military conflicts and was claimed to contribute to health problems, known as the Gulf War Syndrome and recently as the Balkan Syndrome. This led to renewed efforts to assess the environmental consequences and the health impact of the use of DU. The radiological and chemical properties of DU can be compared to those of natural uranium, which is ubiquitously present in soil at a typical concentration of 3 mg/kg. Natural uranium has the same chemotoxicity, but its radiotoxicity is 60% higher. Due to the low specific radioactivity and the dominance of alpharadiation no acute risk is attributed to external exposure to DU. The major risk is DU dust, generated when DU ammunition hits hard targets. Depending on aerosol speciation, inhalation may lead to a protracted exposure of the lung and other organs. After deposition on the ground, resuspension can take place if the DU containing particle size is sufficiently small. However, transfer to drinking water or locally produced food has little potential to lead to significant exposures to DU. Since poor solubility of uranium compounds and lack of information on speciation precludes the use of radioecological models for exposure assessment, biomonitoring has to be used for assessing exposed persons. Urine, feces, hair and nails record recent exposures to DU. With the exception of crews of military vehicles having been hit by DU penetrators, no body burdens above the range of values for natural uranium have been found. Therefore, observable health effects are not expected and residual cancer risk estimates have to be based on theoretical considerations. They appear to be very minor for all post-conflict situations, i.e. a fraction of those expected from natural radiation

Are uranium-contaminated soil and irrigation water a risk for human vegetable consumers? A study case with Solanum tuberosum L., Phaseolus vulgaris L. and Lactuca sativa L.

The knowledge of uranium concentration, in the products entering the human diet is of extreme importance because of their chemical hazard to health. Controlled field experiments with potatoes, beans and lettuce (Solanum tuberosum L., Phaseolus vulgaris L. and Lactuca sativa L.) were carried out in a contaminated soil used by local farmers located near a closed Portuguese uranium mine (Cunha Baixa, Mangualde). The soil with high average uranium levels (64–252 mg/kg) was divided in two plots, and irrigated with non-contaminated and uranium-contaminated water (\20 and [900 lg/L). Uranium maximum average concentration in the edible vegetables parts (mg/kg fresh weight) ranged in the following order: lettuce (234 lg/kg)[green bean (30 lg/kg)[potatoes without peel (4 lg/kg). Although uranium in soil, irrigation water and vegetables was high, the assessment of the health risk based on hazard quotient indicates that consumption of these vegetables does not represent potential adverse (no carcinogenic) effects for a local inhabitant during lifetime

Phenotype of Arabidopsis thaliana semi-dwarfs with deep roots and high growth rates under water-limiting conditions is independent of the GA5 loss-of-function alleles

BACKGROUND AND AIMS: The occurrence of Arabidopsis thaliana semi-dwarf accessions carrying inactive alleles at the gibberellin (GA) biosynthesis GA5 locus has raised the question whether there are pleiotropic effects on other traits at the root level, such as rooting depth. In addition, it is unknown whether semi-dwarfism in arabidopsis confers a growth advantage under water-limiting conditions compared with wild-type plants. The aim of this research was therefore to investigate whether semi-dwarfism has a pleiotropic effect in the root system and also whether semi-dwarfs might be more tolerant of water-limiting conditions. METHODS: The root systems of different arabidopsis semi-dwarfs and GA biosynthesis mutants were phenotyped in vitro using the GROWSCREEN-ROOT image-based software. Semi-dwarfs were phenotyped together with tall, near-related accessions. In addition, root phenotypes were investigated in soil-filled rhizotrons. Rosette growth trajectories were analysed with the GROWSCREEN-FLUORO setup based on non-invasive imaging. KEY RESULTS: Mutations in the early steps of the GA biosynthesis pathway led to a reduction in shoot as well as root size. Depending on the genetic background, mutations at the GA5 locus yielded phenotypes characterized by decreased root length in comparison with related wild-type ones. The semi-dwarf accession Pak-3 showed the deepest root system both in vitro and in soil cultivation experiments; this comparatively deep root system, however, was independent of the ga5 loss-of-function allele, as shown by co-segregation analysis. When the accessions were grown under water-limiting conditions, semi-dwarf accessions with high growth rates were identified. CONCLUSIONS: The observed diversity in root system growth and architecture occurs independently of semi-dwarf phenotypes, and is probably linked to a genetic background effect. The results show that there are no clear advantages of semi-dwarfism at low water availability in arabidopsis.International Max Planck Research School PhD Fellowship/[]/IMPRS/AlemaniaHelmholtz Association//[]//AlemaniaUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Centro para Investigaciones en Granos y Semillas (CIGRAS

Biosorption and Biomineralization of U(VI) by the Marine Bacterium Idiomarina loihiensis MAH1: Effect of Background Electrolyte and pH

The main goal of this study is to compare the effects of pH, uranium concentration, and background electrolyte (seawater and NaClO4 solution) on the speciation of uranium(VI) associated with the marine bacterium Idiomarina loihiensis MAH1. This was done at the molecular level using a multidisciplinary approach combining X-ray Absorption Spectroscopy (XAS), Time-Resolved Laser-Induced Fluorescence Spectroscopy (TRLFS), and High Resolution Transmission Electron Microscopy (HRTEM). We showed that the U(VI)/bacterium interaction mechanism is highly dependent upon pH but also the nature of the used background electrolyte played a role. At neutral conditions and a U concentration ranging from 5·10−4 to 10−5 M (environmentally relevant concentrations), XAS analysis revealed that uranyl phosphate mineral phases, structurally resembling meta-autunite [Ca(UO2)2(PO4)2 2–6H2O] are precipitated at the cell surfaces of the strain MAH1. The formation of this mineral phase is independent of the background solution but U(VI) luminescence lifetime analyses demonstrated that the U(VI) speciation in seawater samples is more intricate, i.e., different complexes were formed under natural conditions. At acidic conditions, pH 2, 3 and 4.3 ([U] = 5·10−4 M, background electrolyte = 0.1 M NaClO4), the removal of U from solution was due to biosorption to Extracellular Polysaccharides (EPS) and cell wall components as evident from TEM analysis. The LIII-edge XAS and TRLFS studies showed that the biosorption process observed is dependent of pH. The bacterial cell forms a complex with U through organic phosphate groups at pH 2 and via phosphate and carboxyl groups at pH 3 and 4.3, respectively. The differences in the complexes formed between uranium and bacteria on seawater compared to NaClO4 solution demonstrates that the actinide/microbe interactions are influenced by the three studied factors, i.e., the pH, the uranium concentration and the chemical composition of the solution.This work was funded by the grants CGL2009-09760 and CGL2012-36505 (Ministerio de Ciencia e Innovación), and RNM 3943 (Junta de Andalucía), Spain

Teratogenicity of depleted uranium aerosols: A review from an epidemiological perspective

BACKGROUND: Depleted uranium is being used increasingly often as a component of munitions in military conflicts. Military personnel, civilians and the DU munitions producers are being exposed to the DU aerosols that are generated. METHODS: We reviewed toxicological data on both natural and depleted uranium. We included peer reviewed studies and gray literature on birth malformations due to natural and depleted uranium. Our approach was to assess the "weight of evidence" with respect to teratogenicity of depleted uranium. RESULTS: Animal studies firmly support the possibility that DU is a teratogen. While the detailed pathways by which environmental DU can be internalized and reach reproductive cells are not yet fully elucidated, again, the evidence supports plausibility. To date, human epidemiological data include case examples, disease registry records, a case-control study and prospective longitudinal studies. DISCUSSION: The two most significant challenges to establishing a causal pathway between (human) parental DU exposure and the birth of offspring with defects are: i) distinguishing the role of DU from that of exposure to other potential teratogens; ii) documentation on the individual level of extent of parental DU exposure. Studies that use biomarkers, none yet reported, can help address the latter challenge. Thoughtful triangulation of the results of multiple studies (epidemiological and other) of DU teratogenicity contributes to disentangling the roles of various potentially teratogenic parental exposures. This paper is just such an endeavor. CONCLUSION: In aggregate the human epidemiological evidence is consistent with increased risk of birth defects in offspring of persons exposed to DU

Untersuchungen zur Pyrolyse von chloraromatischen Verbindungen unter Variation der Pyrolysebedingungen

Die pyrolytische Zersetzung von verschiedenen chlorierten Benzolen (Di- bis Hexachlorbenzol) sowie von Dekachlorbiphenyl ($\textbf{PCB 209}$) und Oktachlornaphthalin ($\textbf{OCN}$) wurde im Rahmen dieser Arbeit untersucht. Dabei wurden die Produktverteilungen und Produktkonzentrationen in Abhängigkeit von der Temperatur (Temperaturbereich 600-1000° C), der Pyrolysezeit (zwischen 1.2 und 20 Sekunden) sowie unter dem Einfluß von anorganischen Zusätzen (Metalle, Metalloxide, Schichtsilikate) in der Pyrolysezone ermittelt. Als Pyrolyseprodukte werden bei der Umsetzung der Chlorbenzole neben isomeren- und höherchlorierten Benzolen vor allem polychlorierte Biphenyle ($\textbf{PCB}$) sowie in geringeren Konzentrationen chlorierte Naphthaline ($\textbf{PCN}$), chlorierte polyzyklische Kohlenwasserstoffe ($\textbf{CI-PAH}$), und chlorierte Biphenylene ($\textbf{PCBN}$) erhalten. Aromatenbruchstücke und damit verbunden Chiorstyrole und Chlorphenylacetylene werden erst oberhalb von ca. 800° C beobachtet. Die höchsten Konzentrationen an PCB werden bei einer Veweilzeit von 10 Sekunden bei Temperaturen von 750° C erhalten. Die entstehenden PCB-Kongenere können im unteren untersuchten Temperaturbereich (ca. 700° C) eindeutig identifiziert werden. Es werden dabei bevorzugt die durch Chlorwasserstoff- oder Wasserstoffabspaltung aus den Edukten entstehenden Kongenere gebildet ($\textbf{'direkte PCB'}$). Bei höheren Temperaturen ist keine Bevorzugung dieser PCB-Kongeneren zu erkennen. Die polychlorierten Biphenylene (PCBN) sind den polychlorierten Biphenylen (PCB) chemisch sehr ähnlich und gaschromatographisch von diesen schwer zu trennen. HoheKonzentrationen an PCB überlagern im Chromatogramm die in geringeren Konzentrationen auftretenden PCBN. Die Massenspektren dieser Verbindungsklassen unterscheiden sich nur um zwei Masseneinheiten und zeigen ähnliche Fragmentierungsmuster. Von den PCBN wurden Kongenere jedes Chlorierungsgrades in den verschiedenen Proben mittels HPLC-UV-Detektion identifiziert. Für die Bildung der PCBN bei der Pyrolyse von Chlorbenzolen ist ein Mechanismus über Arine formuliert worden. Die Existenz von Dehydrobenzol bei der thermischen Umsetzung von Chlorbenzolen konnte durch Abfangen eines Diels-Alder-Produktes bei der Pyrolyse von Pentachlorbenzol in Gegenwart von Anthracen bewiesen werden. Eine thermodynamische Berechnung der Bildung von Oktachlorbiphenylen (OCBN) über Tetrachlordehydrobenzol aus Pentachlorbenzol ergibt aber, daß dieser $\textbf{'Arinmechanismus'}$ für die thermische Zersetzung von Chloraromaten gegenüber radikalischen Mechanismen nur eine untergeordnete Bedeutung besitzt. Im Gegensatz zu den Pyrolysen der Chlorbenzole ergibt die thermische Umsetzung von synthetisiertem Dekachlorbiphenyl ($\textbf{PCB 209}$) bis zu Temperaturen von 900° C als [...

Untersuchungen zur Pyrolyse von chloraromatischen Verbindungen unter Variation der Pyrolysebedingungen

The pyrolytic decomposition of various chlorinated benzenes (di- to hexachlorobenzene) and of decachlorobiphenyl and octachloronaphthalin was investigated. Product distributions and concentrations were determined as a function of temperature (600-1000 C), pyrolysis time and inorganic additives (metals, metal oxides, stratified silicates) in the pyrolysis zone. (orig./SR)Die pyrolytische Zersetzung von verschiedenen chlorierten Benzolen (Di- bis Hexachlorbenzol) sowie von Dekachlorbiphenyl und Oktachlornaphtalin wurde im Rahmen dieser Arbeit untersucht. Dabei wurden die Produktverteilungen und Produktkonzentrationen in Abhaengigkeit von der Temperature (Temperaturbereich 600-1000 C), der Pyrolysezeit sowie unter dem Einfluss von anorganischen Zusaetzen (Metalle, Metalloxide, Schichtsilikate) in der Pyrolysezone ermittelt. (orig./SR)Available from TIB Hannover: RA 831(3075) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman