Review

Authors: Bárbara Maria Teixeira Costa Peluzo, Elfi Kraka

This review summarizes the recent developments regarding the use of uranium as nuclear fuel, including recycling and health aspects, elucidated from a chemical point of view, i.e., emphasizing the rich uranium coordination chemistry, which has also raised interest in using uranium compounds in synthesis and catalysis. A number of novel uranium coordination features are addressed, such the emerging number of U(II) complexes and uranium nitride complexes as a promising class of materials for more efficient and safer nuclear fuels. The current discussion about uranium triple bonds is addressed by quantum chemical investigations using local vibrational mode force constants as quantitative bond strength descriptors based on vibrational spectroscopy. The local mode analysis of selected uranium nitrides, N≡U≡N, U≡N, N≡U=NH and N≡U=O, could confirm and quantify, for the first time, that these molecules exhibit a UN triple bond as hypothesized in the literature. We hope that this review will inspire the community interested in uranium chemistry and will serve as an incubator for fruitful collaborations between theory and experimentation in exploring the wealth of uranium chemistry.

Topics: Catalysis; Spectrum Analysis; Uranium; Vibration

PubMed: 35563047
DOI: 10.3390/ijms23094655

Review

Authors: Jodi R Schilz, Erica J Dashner-Titus, Karen A Simmons...

Uranium is a naturally occurring element found in the environment as a mixture of isotopes with differing radioactive properties. Enrichment of mined material results in depleted uranium waste with substantially reduced radioactivity but retains the capacity for chemical toxicity. Uranium mine and milling waste are dispersed by wind and rain leading to environmental exposures through soil, air, and water contamination. Uranium exposure is associated with numerous adverse health outcomes in humans, yet there is limited understanding of the effects of depleted uranium on the immune system. The purpose of this review is to summarize findings on uranium immunotoxicity obtained from cell, rodent and human population studies. We also highlight how each model contributes to an understanding of mechanisms that lead to immunotoxicity and limitations inherent within each system. Information from population, animal, and laboratory studies will be needed to significantly expand our knowledge of the contributions of depleted uranium to immune dysregulation, which may then inform prevention or intervention measures for exposed communities.

Topics: Animals; Environmental Exposure; Humans; Mining; Soil; Uranium; Water

PubMed: 36152676
DOI: 10.1016/j.taap.2022.116252

Review

Authors: Nicole Redvers, Ann Marie Chischilly, Donald Warne...

BACKGROUND

Uranium contamination of drinking-water sources on American Indian (AI) reservations in the United States is a largely ignored and underfunded public health crisis. With an estimated 40% of the headwaters in the western U.S. watershed, home to many AI reservation communities, being contaminated with untreated mine waste, the potential health effects have largely been unexplored. With AI populations already facing continued and progressive economic and social marginalization, higher prevalence of chronic disease, and systemic discrimination, associations between various toxicant exposures, including uranium, and various chronic conditions, need further examination.

OBJECTIVES

Uranium's health effects, in addition to considerations for uranium drinking-water testing, reporting, and mitigation in reference to AI communities through the lens of water quality, is reviewed.

DISCUSSION

A series of environmental health policy recommendations are described with the intent to proactively improve responsiveness to the water quality crisis in AI reservation communities in the United States specific to uranium. There is a serious and immediate need for better coordination of uranium-related drinking-water testing and reporting on reservations in the United States that will better support and guide best practices for uranium mitigation efforts. https://doi.org/10.1289/EHP7537.

Topics: Environmental Health; Hazardous Substances; Humans; Indians, North American; Policy; United States; Uranium; American Indian or Alaska Native

PubMed: 33769848
DOI: 10.1289/EHP7537

Authors: Shelby Surdyk, Moustapha Itani, Mais Al-Lobaidy...

BACKGROUND

The US military first deployed depleted uranium (DU) weapons in Iraq during the Gulf War in 1990 and in the 2003 invasion of Iraq. Research into the health impacts of DU has been mired in debate and controversy. Research funded by the US government has denied the health risks posed by DU to the Iraqi population, while opponents have claimed that DU is responsible for increased rates of birth defects and cancers in Iraq. Others assert that the public health impacts of DU weapons remain uncertain. This systematic review identified, appraised and synthesised all human observational studies assessing adverse health outcomes associated with DU exposure among the Iraqi population. To our knowledge, no systematic review has been conducted on the topic previously.

METHODS

We searched 11 electronic databases for human observational studies published between 1990 and 2020 that measured association between exposure to weaponised uranium and health outcomes (including cancer, birth defects, immune system function and mortality) among the Iraqi population. We assessed risk of bias using the Navigation Guide's risk of bias tool and rated certainty of the evidence using the Grading of Recommendations, Assessment, Development and Evaluations approach (PROSPERO: CRD42018108225).

RESULTS

Our searches identified 2601 records, of which 28 met our inclusion criteria. We identified five additional eligible reports from other sources. Two articles reported the results of multiple relevant studies; our final set included 33 articles reporting on 36 eligible studies. Most studies (n=30, 83%) reported a positive association between uranium exposure and adverse health outcomes. However, we found that the reviewed body of evidence suffers from a high risk of bias.

CONCLUSION

The available evidence suggests possible associations between exposure to depleted uranium and adverse health outcomes among the Iraqi population. More primary research and the release of missing data are needed to design meaningful health and policy interventions in Iraq.

Topics: Humans; Iraq; Outcome Assessment, Health Care; Public Health; Uranium

PubMed: 33619039
DOI: 10.1136/bmjgh-2020-004166

Authors: Dengqin Zhong, Ruiyun Wang, Hongjing Zhang...

Uranium (U) is a well-known nephrotoxicant which forms precipitates in the lysosomes of renal proximal tubular epithelial cells (PTECs) after U-exposure at a cytotoxic dose. However, the roles of lysosomes in U decorporation and detoxification remain to be elucidated. Mucolipin transient receptor potential channel 1 (TRPML1) is a major lysosomal Ca channel regulating lysosomal exocytosis. We herein demonstrate that the delayed administration of the specific TRPML1 agonist ML-SA1 significantly decreases U accumulation in the kidney, mitigates renal proximal tubular injury, increases apical exocytosis of lysosomes and reduces lysosomal membrane permeabilization (LMP) in renal PTECs of male mice with single-dose U poisoning or multiple-dose U exposure. Mechanistic studies reveal that ML-SA1 stimulates intracellular U removal and reduces U-induced LMP and cell death through activating the positive TRPML1-TFEB feedback loop and consequent lysosomal exocytosis and biogenesis in U-loaded PTECs in vitro. Together, our studies demonstrate that TRPML1 activation is an attractive therapeutic strategy for the treatment of U-induced nephrotoxicity.

Topics: Male; Mice; Animals; Uranium; Lysosomes; Exocytosis; Transient Receptor Potential Channels; Calcium

PubMed: 37414766
DOI: 10.1038/s41467-023-39716-7

Authors: A Rump, C Hermann, A Lamkowski...

Uranium and thorium are heavy metals, and all of their isotopes are radioactive, so it is impossible to study chemical effects entirely independent of the radiation effects. In the present study, we tried to compare the chemo- and radiotoxicity of both metals, taking into account deterministic radiation damages reflected by acute radiation sickness and stochastic radiation damages leading to long-term health impairments (e.g., tumor induction). We made at first a literature search on acute median lethal doses that may be expected to be caused by chemical effects, as even acute radiation sickness as a manifestation of acute radiotoxicity occurs with latency. By simulations based on the biokinetic models of the International Commission on Radiological Protection and using the Integrated Modules for Bioassay Analysis software, we determined the amounts of uranium at different enrichment grades and thorium-232 leading to a short-term red bone marrow equivalent dose of 3.5 Sv considered to cause 50% lethality in humans. Different intake pathways for incorporation were considered, and values were compared to the mean lethal doses by chemotoxicity. To assess stochastic radiotoxicity, we calculated the uranium and thorium amounts leading to a committed effective dose of 200 mSv that is often considered critical. Mean lethal values for uranium and thorium are in the same order of magnitude so that the data do not give evidence for substantial differences in acute chemical toxicity. When comparing radiotoxicity, the reference units (activity in Bq or weight in g) must always be taken into account. The mean lethal equivalent dose to the red bone marrow of 3.5 Sv is reached by lower activities of thorium compared to uranium in soluble compounds. However, for uranium as well as thorium-232, acute radiation sickness is expected only after incorporation of amounts exceeding the mean lethal doses by chemotoxicity. Thus, acute radiation sickness is not a relevant clinical issue for either metal. Concerning stochastic radiation damages, thorium-232 is more radiotoxic than uranium if incorporating the same activities. Using weight units for comparison show that for soluble compounds, thorium-232 is more radiotoxic than low-enriched uranium in the case of ingestion but even more toxic than high-enriched uranium after inhalation or intravenous administration. For insoluble compounds, the situation differs as the stochastic radiotoxicity of thorium-232 ranges between depleted and natural uranium. For acute effects, the chemotoxicity of uranium, even at high enrichment grades, as well as thorium-232 exceeds deterministic radiotoxicity. Simulations show that thorium-232 is more radiotoxic than uranium expressed in activity units. If the comparison is based on weight units, the rankings depend on the uranium enrichment grades and the route of intake.

Topics: Humans; Thorium; Uranium; Dose-Response Relationship, Radiation; Radiation Injuries

PubMed: 37022444
DOI: 10.1007/s00204-023-03484-6

Authors: Mostafa M S Ismaiel, Yassin M El-Ayouty, Saad A Abdelaal...

Different activities related to uranium mining and nuclear industry may have a negative impact on the environment. Bioremediation of nuclear pollutants using microorganisms is an effective, safe, and economic method. The present study compared the uranium biosorption efficiency of two immobilized algae: Nostoc sp. (cyanophyte) and Scenedesmus sp. (chlorophyte). Effects of metal concentration, contact time, pH, and biosorbent dosage were also studied. The maximum biosorption capacity (60%) by Nostoc sp. was obtained at 300 mg/l uranium solution, 60 min, pH 4.5, and 4.2 g/l algal dosage, whereas Scenedesmus sp. maximally absorbed uranium (65 %) at 150 mg/l uranium solution, 40 min, pH 4.5, and 5.6 g/l of algal dosage. The interaction of metal ions as NaSO, FeCl, CuCl, NiCl, CoCl, CdCl, and AlCl did not support the uranium biosorption by algae. The obtained data was adapted to the linearized form of the Langmuir isotherm model. The experimental q values were 130 and 75 mg/g for Nostoc sp. and Scenedesmus sp., respectively. Moreover, the pseudo-second-order kinetic model was more applicable, as the calculated parameters were close to the experimental data. The biosorbents were also characterized by Fourier-transform infrared spectroscopy (ATR-FTIR), energy-dispersive X-ray spectroscopy (EDX), and scanning electron microscopy (SEM) analyses. The results suggest the applicability of algae, in their immobilized form, for recovery and biosorption of uranium from aqueous solution.

Topics: Uranium; Scenedesmus; Adsorption; Nostoc; Kinetics; Water Pollutants, Chemical; Ions; Spectroscopy, Fourier Transform Infrared; Hydrogen-Ion Concentration; Thermodynamics

PubMed: 35771321
DOI: 10.1007/s11356-022-21641-9

Authors: Sharly Coombs, Darrah K Sleeth, Rachael M Jones...

A scoping review was performed to answer: what environmental health concerns have been associated with adverse health outcomes in the Navajo Nation? The review focused on occupational and ambient environmental exposures associated with human industrial activities. The search strategy was implemented in PubMed, and two investigators screened the retrieved literature. Thirteen studies were included for review. Data were extracted using the matrix method. Six studies described associations between work in uranium mining and cancer. Six studies focused on environmental exposures to uranium mine waste and other metals, with outcomes that included biological markers, kidney disease, diabetes and hypertension, and adverse birth outcomes. One study explored occupational exposure to Sin Nombre Virus and infection. Most research has focused on the health effects of uranium, where occupational exposures occurred among miners and environmental exposures are a legacy of uranium mining and milling. Gaps exist with respect to health outcomes associated with current occupations and the psychosocial impact of environmental hazards. Other environmental exposures and hazards are known to exist on the Navajo Nation, which may warrant epidemiologic research.

Topics: Environmental Exposure; Humans; Mining; Occupational Diseases; Occupational Exposure; Occupational Health; Uranium

PubMed: 34968017
DOI: 10.1515/reveh-2021-0118

Authors: Liqun Huang, Shufang Li, Wenhua Zhou...

Uranium is a radioactive heavy metal and a significant public health concern; however, its associated underlying toxicological mechanisms remain largely unknown. In this work, the uptake and efflux processes of uranium in CHO-k1 cells were studied and the cytotoxicity effects were explored. It was found that both the uptake and efflux processes took place rapidly and half of the internalized uranium was expelled within 8 h. The uranium exposure caused a decrease of cell viability and adhesion ability in a dose-dependent manner and blocked the cell cycle at the G1 stage. In addition, gene expression analysis revealed relative changes in the transcription of metabolism related genes. Further studies revealed that the cytotoxicity of uranium could be alleviated by exposing cells to a lower temperature or by the addition of amantadine-HCl, an endocytosis inhibitor. Interestingly, after uranium exposure, needle-like precipitates were observed in both intracellular and extracellular regions. These findings collectively suggest that the cellular transport of uranium is a rapid process that disturbs cell metabolism and induces cytotoxicity, and this impact could be reduced by slowing down endocytic processes.

Topics: Cricetinae; Animals; Uranium; Cricetulus; CHO Cells; Cell Survival; Endocytosis

PubMed: 36228352
DOI: 10.1016/j.ecoenv.2022.114166

Authors: Laurie De Castro, Annabelle Manoury, Olivier Claude...

During nuclear fuel processing, workers can potentially be exposed to repeated inhalations of uranium compounds. Uranium nephrotoxicity is well documented after acute uranium intake, but it is controversial after long-term or protracted exposure. This study aims to analyze the nephrotoxicity threshold after repeated uranium exposure through upper airways and to investigate the resulting uranium biokinetics in comparison to reference models. Mice (C57BL/6J) were exposed to uranyl nitrate (0.03-3 mg/kg/day) via intranasal instillation four times a week for two weeks. Concentrations of uranium in urines and tissues were measured at regular time points (from day 1 to 91 post-exposure). At each exposure level, the amount of uranium retained in organs/tissues (kidney, lung, bone, nasal compartment, carcass) and excreta (urine, feces) reflected the two consecutive weeks of instillation except for renal uranium retention for the highest uranium dose. Nephrotoxicity biomarkers, KIM-1, clusterin and osteopontin, are induced from day 4 to day 21 and associated with changes in renal function (arterial fluxes) measured using non-invasive functional imaging (Doppler-ultrasonography) and confirmed by renal histopathological analysis. These results suggest that specific biokinetic models should be developed to consider altered uranium excretion and retention in kidney due to nephrotoxicity. The threshold is between 0.25 and 1 mg/kg/day after repeated exposure to uranium via upper airways.

Topics: Mice; Animals; Uranium; Mice, Inbred C57BL; Kidney; Feces; Body Fluids

PubMed: 36914734
DOI: 10.1038/s41598-023-31073-1