Uranium bone content as an indicator of chronic environmental exposure from drinking water

An overview of the heat-induced changes of the chemical composition of bone from fresh to calcined

When bone is exposed to thermal stress, the chemical composition changes. This affects bone tissue regeneration after surgery, and these changes can also aid in reconstructing ante-, peri-, and post-mortem events in forensic investigations and past activities on cremation practices in archaeology. However, to date, no complete overview exists on the chemical composition of both fresh and thermally altered bone. Therefore, we aimed (i) to present the chemical composition of fresh bone and (ii) to present an overview of heat-induced chemical changes in bone under both reducing and oxidizing conditions. From the overview, it became clear that some chemical changes occur at a consistent temperature, independent of exposure duration, meaning there is a temperature threshold. However, the occurrence of other chemical changes appeared to be more inter-experimentally variable, and therefore, it is recommended to further investigate these changes.

Levels of naturally occurring radioisotopes in local and imported bottled drinking water available in Québec City, Canada

Consumption of local and imported bottled water in Canada has greatly increased during the past three decades. While the presence of natural radioactivity is often overlooked when dealing with the water quality of these bottled products, it could contribute substantially to the uptake of radionuclides especially when sourced from regions with higher radioactivity levels compared to where it is consumed. In this study, the activity of several naturally occurring radionuclides (i.e., 210Po, 226,228Ra, 230,232Th, 234,235,238U) were measured in bottled water available in Québec, Canada after sample pretreatment and analysis by either radiometric or mass spectrometry approaches. 230,232Th and 228Ra concentrations were below minimum detectable activity levels in all samples tested. Analytical results for 234U, 235U, 238U, and 226Ra showed concentrations that ranged from 0.38 to 115 mBq/L, (2.2-313) x 10-2 mBq/L, 0.48-58.4 mBq/L, and 1.1-550 mBq/L, respectively. 210Po was detected in only 5 samples and its activity ranged from 2 to 26 mBq/L. To determine variability in activity within brands, the same brands of bottled water were purchased during two consecutive years and analyzed. The possible radiological impact of the consumption of these types of water was assessed based on different drinking habit scenarios. Some of the imported water brands showed higher activity concentrations than local sources or tap water, suggesting that individuals drinking predominantly imported bottled water would receive a higher radiation dose than those who drink mainly local water.

Significance of MOF adsorbents in uranium remediation from water

Uranium is considered as one of the most perilous radioactive contaminants in the aqueous environment. It has shown detrimental effects on both flora and fauna and because of its toxicities on human beings, therefore its exclusion from the aqueous environment is very essential. The utilization of metal-organic frameworks (MOFs) as an adsorbent for the removal of uranium from the aqueous environment could be a good approach. MOFs possess unique properties like high surface area, high porosity, adjustable pore size, etc. This makes them promising adsorbents for the removal of uranium from contaminated water. In this paper, sources of uranium in the water environment, human health disorders, and application of the different types of MOFs as well as the mechanisms of uranium removal have been discussed meticulously.

Assessment of groundwater geochemistry using multivariate water quality index and potential health risk in industrial belt of central Odisha, India

Groundwater in India has been shown to have a variety of water quality issues, including fluoride, nitrate, and uranium pollution, all of which pose a health risk to humans. In the present study, a total of 106 groundwater samples from the Angul district of Odisha, an industrialized region in India, were analyzed for 14 different hydrochemical parameters. In almost 30%, 34.9%, and 4.7% of the groundwater samples, the concentrations of F-, NO^3- and uranium, respectively, exceeded the permissible limit set by WHO. In addition to the fixed-weight groundwater quality index (GWQI), the entropy-weighted water quality index (EWQI), the principal component analysis (PCA) factor (or rotated factor) loading based water quality index (PCWQI) and human health risk assessment were used. Depending on the models, about 19.1 ± 0.9%, 70.5 ± 1.9% and 10.38 ± 1.9% of water samples were classified as "Excellent", "Good" and "Medium" quality, respectively, across four water quality indexes with a nominal rating disagreement of 11.3%. More than 90% of samples are unanimously classified as excellent or good across the WQI rating. For children and adults, approximately 54.7% and 24.5% of samples exceeded the permitted limit for F^-, (hazard quotient HQ > 1), posing non-carcinogenic health hazards, respectively. In contrast, 71.7% and 34.9% of NO₃^- samples respectively, surpassed the allowed limit and caused non-carcinogenic health concerns for children and adults. In terms of carcinogenic HQ values, about 13.2% and 7.5% of samples exhibit an uranium related carcinogenic health risk in children and adults, respectively. The existence of significant amounts of Cl ^-, NO₃^-, and especially HCO₃^- ions in groundwater in some samples, as well as their positive interdependence, may increase uranium pollution in the future through uranium dissolution.

Low doses of uranium and osteoclastic bone resorption: key reciprocal effects evidenced using new in vitro biomimetic models of bone matrix

Uranium is widely spread in the environment due to its natural and anthropogenic occurrences, hence the importance of understanding its impact on human health. The skeleton is the main site of long-term accumulation of this actinide. However, interactions of this metal with biological processes involving the mineralized extracellular matrix and bone cells are still poorly understood. To get a better insight into these interactions, we developed new biomimetic bone matrices containing low doses of natural uranium (up to 0.85 µg of uranium per cm²). These models were characterized by spectroscopic and microscopic approaches before being used as a support for the culture and differentiation of pre-osteoclastic cells. In doing so, we demonstrate that uranium can exert opposite effects on osteoclast resorption depending on its concentration in the bone microenvironment. Our results also provide evidence for the first time that resorption contributes to the remobilization of bone matrix-bound uranium. In agreement with this, we identified, by HRTEM, uranium phosphate internalized in vesicles of resorbing osteoclasts. Thanks to the biomimetic matrices we developed, this study highlights the complex mutual effects between osteoclasts and uranium. This demonstrates the relevance of these 3D models to further study the cellular mechanisms at play in response to uranium storage in bone tissue, and thus better understand the impact of environmental exposure to uranium on human bone health.

Emerging health risks and underlying toxicological mechanisms of uranium contamination: Lessons from the past two decades

Uranium contamination is a global health concern. Regarding natural or anthropogenic uranium contamination, the major sources of concern are groundwater, mining, phosphate fertilizers, nuclear facilities, and military activities. Many epidemiological and laboratory studies have demonstrated that environmental and occupational uranium exposure can induce multifarious health problems. Uranium exposure may cause health risks because of its chemotoxicity and radiotoxicity in natural or anthropogenic scenarios: the former is generally thought to play a more significant role with regard to the natural uranium exposure, and the latter is more relevant to enriched uranium exposure. The understanding of the health risks and underlying toxicological mechanisms of uranium remains at a preliminary stage, and many controversial findings require further research. In order to present state-of-the-art status in this field, this review will primarily focus on the chemotoxicity of uranium, rather than its radiotoxicity, as well as the involved toxicological mechanisms. First, the natural or anthropogenic uranium contamination scenarios will be briefly summarized. Second, the health risks upon natural uranium exposure, for example, nephrotoxicity, bone toxicity, reproductive toxicity, hepatotoxicity, neurotoxicity, and pulmonary toxicity, will be discussed based on the reported epidemiological cases and laboratory studies. Third, the recent advances regarding the toxicological mechanisms of uranium-induced chemotoxicity will be highlighted, including oxidative stress, genetic damage, protein impairment, inflammation, and metabolic disorder. Finally, the gaps and challenges in the knowledge of uranium-induced chemotoxicity and underlying mechanisms will be discussed.

Ghrelin protects against depleted uranium-induced apoptosis of MC3T3-E1 cells through oxidative stress-mediated p38-mitogen-activated protein kinase pathway

Depleted uranium (DU) mainly accumulates in the bone over the long term. Osteoblast cells are responsible for the formation of bone, and they are sensitive to DU damage. However, studies investigating methods of reducing DU damage in osteoblasts are rarely reported. Ghrelin is a stomach hormone that stimulates growth hormones released from the hypothalamic-pituitary axis, and it is believed to play an important physiological role in bone metabolism. This study evaluates the impact of ghrelin on DU-induced apoptosis of the osteoblast MC3T3-E1 and investigates its underlying mechanisms. The results show that ghrelin relieved the intracellular oxidative stress induced by DU, eliminated reactive oxygen species (ROS) and reduced lipid peroxidation by increasing intracellular GSH levels; in addition, ghrelin effectively suppressed apoptosis, enhanced mitochondrial membrane potential, and inhibited cytochrome c release and caspase-3 activation after DU exposure. Moreover, ghrelin significantly reduced the expression of DU-induced phosphorylated p38-mitogen-activated protein kinase (MAPK). A specific inhibitor (SB203580) or specific siRNA of p38-MAPK could significantly suppress DU-induced apoptosis and related signals, whereas ROS production was not affected. In addition, ghrelin receptor inhibition could reduce the anti-apoptosis effect of ghrelin on DU and reverse the effect of ghrelin on intracellular ROS and p38-MAPK after DU exposure. These results suggest that ghrelin can suppress DU-induced apoptosis of MC3T3-E1 cells, reduce DU-induced oxidative stress by interacting with its receptor, and inhibit downstream p38-MAPK activation, thereby suppressing the mitochondrial-dependent apoptosis pathway.

Chelation therapy for treatment of systemic intoxication with uranium: A review

Elevated levels of naturally occurring uranium have been found in small geographic areas throughout the world. Exposure of the general public to uranium is most often by the ingestion of food and water containing natural uranium from the hydrogeological environment, but this likelihood is remote. However, the risk is increased in regions where uranium is mined, milled, processed and/or fabricated as well as in the vicinity of former battlefields where depleted uranium munitions were deployed. Exposure in such cases is by the inhalation route. Internalized uranium is a long-term hazard the toxicity of which depends upon the dose and the dose rate as well as other parameters such as the chemical form and site of deposition of the uranium and the physiology of the host. The radiological toxicity and the chemical toxicity of uranium and its compounds are responsible for kidney damage and lung cancer. The vulnerable groups are the very young and the very old, individuals predisposed to hypertension or osteoporosis and individuals with chronic kidney disease. Those subject to long-term exposure from internalized uranium are a greater risk for the long-term implications. The accumulation of uranium may be mitigated by decreasing its absorption, distribution and deposition and increasing its elimination with chelating agents. The formation of soluble chelates may enhance the mobilization of uranium deposited in tissue and expedite its transport to and elimination from the renal system. The focus of this review is on the use of chelating agents to enhance decorporation of uranium thereby reducing the risk of intoxication.

Modes of action associated with uranium induced adverse effects in bone function and development

Uranium, a naturally occurring element used in military and industrial applications, accumulates in the skeletal system of animals and humans. Evidence from animal and in-vitro studies demonstrates that uranium exposure is associated with alterations in normal bone functions. The available studies suggest that upon absorption uranium directly affects bone development and maintenance by inhibiting osteoblast differentiation and normal functions, and indirectly by disrupting renal production of Vitamin D. Animal studies also provide evidence for increased susceptibility to uranium-induced bone toxicity during early life stages. The objective of this review is to provide a summary of uranium-induced bone toxicity and the potential mechanisms by which uranium can interfere with bone development and promote fragility. Since normal Vitamin D production and osteoblast functions are essential for bone growth and maintenance, young individuals and the elderly may represent potentially susceptible populations to uranium-induced bone damage.

Uranium in Kosovo's drinking water

The results of this paper are an initiation to capture the drinking water and/or groundwater elemental situation in the youngest European country, Kosovo. We aim to present a clear picture of the natural uranium concentration in drinking water and/or groundwater as it is distributed to the population of Kosovo. Nine hundred and fifty-one (951) drinking water samples were analyzed by inductively coupled plasma mass spectrometry (ICPMS). The results are the first countrywide interpretation of the uranium concentration in drinking water and/or groundwater, directly following the Kosovo war of 1999. More than 98% of the samples had uranium concentrations above 0.01 μg L(-1), which was also our limit of quantification. Concentrations up to 166 μg L(-1) were found with a mean of 5 μg L(-1) and median 1.6 μg L(-1) were found. Two point six percent (2.6%) of the analyzed samples exceeded the World Health Organization maximum acceptable concentration of 30 μg L(-1), and 44.2% of the samples exceeded the 2 μg L(-1) German maximum acceptable concentrations recommended for infant food preparations.