The Impact of Thallium Exposure in Public Health and Molecular Toxicology: A Comprehensive Review.

This review offers a synthesis of the current understanding of the impact of low-dose thallium (Tl) on public health, specifically emphasizing its diverse effects on various populations and organs. The article integrates insights into the cytotoxic effects, genotoxic potential, and molecular mechanisms of thallium in mammalian cells. Thallium, a non-essential heavy metal present in up to 89 different minerals, has garnered attention due to its adverse effects on human health. As technology and metallurgical industries advance, various forms of thallium, including dust, vapor, and wastewater, can contaminate the environment, extending to the surrounding air, water sources, and soil. Moreover, the metal has been identified in beverages, tobacco, and vegetables, highlighting its pervasive presence in a wide array of food sources. Epidemiological findings underscore associations between thallium exposure and critical health aspects such as kidney function, pregnancy outcomes, smoking-related implications, and potential links to autism spectrum disorder. Thallium primarily exerts cellular toxicity on various tissues through mitochondria-mediated oxidative stress and endoplasmic reticulum stress. This synthesis aims to shed light on the intricate web of thallium exposure and its potential implications for public health, emphasizing the need for vigilant consideration of its risks.

Anthropogenic Forcing of the Baltic Sea Thallium Cycle.

Anthropogenic activities have fundamentally changed the chemistry of the Baltic Sea. According to results reported in this study, not even the thallium (Tl) isotope cycle is immune to these activities. In the anoxic and sulfidic ("euxinic") East Gotland Basin today, Tl and its two stable isotopes are cycled between waters and sediments as predicted based on studies of other redox-stratified basins (e.g., the Black Sea and Cariaco Trench). The Baltic seawater Tl isotope composition (ε205Tl) is, however, higher than predicted based on the results of conservative mixing calculations. Data from a short sediment core from East Gotland Basin demonstrates that this high seawater ε205Tl value originated sometime between about 1940 and 1947 CE, around the same time other prominent anthropogenic signatures begin to appear in the same core. This juxtaposition is unlikely to be coincidental and suggests that human activities in the surrounding area have altered the seawater Tl isotope mass-balance of the Baltic Sea.

Physiology and molecular basis of thallium toxicity and accumulation in Arabidopsis thaliana.

Thallium (Tl) is a non-essential metal mobilized through industrial processes which can lead to it entering the environment and exerting toxic effects. Plants are fundamental components of all ecosystems. Therefore, understanding the impact of Tl on plant growth and development is of great importance for assessing the potential environmental risks of Tl. Here, the responses of Arabidopsis thaliana to Tl were elucidated using physiological, genetic, and transcriptome analyses. Thallium can be absorbed by plant roots and translocated to the aerial parts, accumulating at comparable concentrations throughout plant parts. Genetic evidence supported the regulation of Tl uptake and movement by different molecular compartments within plants. Thallium primarily caused growth inhibition, oxidative stress, leaf chlorosis, and the impairment of K homeostasis. The disturbance of redox balance toward oxidative stress was supported by significant differences in the expression of genes involved in oxidative stress and antioxidant defense under Tl exposure. Reduced GSH levels in cad2-1 mutant rendered plants highly sensitive to Tl, suggesting that GSH has a prominent role in alleviating Tl-triggered oxidative responses. Thallium down-regulation of the expression of LCHII-related genes is believed to be responsible for leaf chlorosis. These findings illuminate some of the mechanisms underlying Tl toxicity at the physiological and molecular levels in plants with an eye toward the future environment management of this heavy metal.

Cotransport of aged biochar colloids and thallium(I) in water-saturated porous media: Impact of the ionic strength, pH and aging degree.

Biochar colloids entering the soil undergo aging over time and exhibit strong capabilities in adsorbing and transporting pollutants. Therefore, investigating the cotransport of aged biochar colloids and thallium (Tl(I)) in quartz sand media is crucial for understanding Tl(I) migration in underground environments. This study investigated the migration of biochar colloids with two different aging degrees and Tl(I) in quartz sand media at various pH and ionic strengths (ISs). The results revealed that under all ISs and pH, 30%AWB (biochar aged with 30 % (w/w) HNO3) inhibited Tl(I) migration in media. This inhibition primarily arose from the introduction of hydroxyl and carboxyl groups during aging, which significantly enhanced colloid adsorption onto Tl(I). At lower ISs, 30%AWB colloids exhibited greater inhibition of Tl(I) migration due to their increased adsorption capacity. Additionally, aging promoted the migration of biochar colloids in the media. Greater biochar aging notably enhanced this promotion, potentially owing to reduced colloidal particle size and the formation of biochar derivatives. Moreover, 50%AWB (biochar aged with 50 % (w/w) HNO3) inhibited Tl(I) migration under low ISs but had almost no impact under high ISs. Nonetheless, at high pH, 50%AWB colloids facilitated Tl(I) migration. This phenomenon might be attributed to the inhibitory effect of aged biochar colloids on Tl(I) adsorption onto media at a high pH, as well as the stable binding between Tl(I) and aged biochar colloids. This study discusses the cotransport of biochar with various degrees of aging and Tl(I) in media, providing insights into remediating soils contaminated with Tl.

[Association of metal/metalloids exposure with abnormal liver function among occupational population in a mining area of Hunan Province:a prospective study].

OBJECTIVE: To investigate the association of metals/metalloids exposure with risk of liver disfunction among occupational population in Hunan Province, and to explore the potential dose-response relationship. METHODS: In 2017, a mining area in Hunan Province was chosen as the research site, and eligible workers were recruited as study subjects. General demographic characteristics, levels of 23 metals/metalloids in plasma and urine, and liver function index(total bilirubin(TBIL), alanine amino transferase(ALT), globulin(GLB) and γ-glutamyl transferase(GGT)) were obtained by questionnaire, physical examination and laboratory tests. Participants were followed up in 2018, 2019 and 2020 respectively. Cox proportional risk model was used to evaluate the relationship between metal/metalloids exposure and risk of liver disfunction, and dose-response relationship curves were plotted by using the restricted cubic spline function. RESULTS: A total of 891 employees were recruited in the study, 576(65.0%)were aged ≤45 years, 832(93.4%) were male and 530(59.5%) worked as smelters. After adjusting various factors such as age, gender, BMI, type of work, education, smoking, alcohol consumption, diet, stress, medical history, exercise and tea consumption, positive correlations were found between plasma tungsten(HR=4.90, 95%CI 1.17-20.48) and urinary barium(HR=1.07, 95%CI 1.02-1.12) levels with abnormally elevated TBIL levels. Additionally, a significant association was observed between plasma thallium and the risk of elevated ALT levels(HR=11.15, 95%CI 1.97-63.29). CONCLUSION: Plasma tungsten and thallium, along with barium found in urine, are risk factors for the development of abnormally elevated liver function indices in occupational groups.

[Determination of 24 elements migration in Yixing clay pottery by inductively coupled plasma mass spectrometry].

OBJECTIVE: To establish an analytical method for determining the migration of 24 elements in Yixing clay pottery in 4% acetic acid simulated solution by inductively coupled plasma mass spectrometry. METHODS: Four types of Yixing clay pottery, including Yixing clay teapot, Yixing clay kettle, Yixing clay pot, and Yixing clay electric stew pot, were immersed in 4% acetic acid as a food simulant for testing. The migration amount of 24 elements in the migration solution was determined using inductively coupled plasma mass spectrometry. RESULTS: Lithium, magnesium, aluminum, iron, and barium elements with a mass concentration of 1000 µg/L; Lead, cadmium, total arsenic, chromium, nickel, copper, vanadium, manganese, antimony, tin, zinc, cobalt, molybdenum, silver, beryllium, thallium, titanium, and strontium elements within 100 µg/L there was a linear relationship within, the r value was between 0.998 739 and 0.999 989. Total mercury at 5.0 µg/L, there was a linear relationship within, the r value of 0.995 056. The detection limit of the elements measured by this method was between 0.5 and 45.0 µg/L, the recovery rate was 80.6%-108.9%, and the relative standard deviation was 1.0%-4.8%(n=6). A total of 32 samples of four types of Yixing clay pottery sold on the market, including teapots, boiling kettles, casseroles, and electric stewing pots, were tested. It was found that the migration of 16 elements, including beryllium, titanium, chromium, nickel, cobalt, zinc, silver, cadmium, antimony, total mercury, thallium, tin, copper, total arsenic, molybdenum, and lead, were lower than the quantitative limit. The element with the highest migration volume teapot was aluminum, magnesium, and barium; The kettle was aluminum and magnesium; Casserole was aluminum, magnesium, and lithium; The electric stew pot was aluminum. CONCLUSION: This method is easy to operate and has high accuracy, providing an effective and feasible detection method for the determination and evaluation of element migration in Yixing clay pottery.

Exposure to heavy metals and trace elements among pregnant women with twins: levels and association with twin growth discordance.

Background: Twin growth discordance is one of the leading causes of perinatal mortality in twin pregnancies. Whether prenatal exposure to heavy metals and trace elements is associated with twin growth discordance has not been studied yet. Objective: To evaluate the prenatal level of heavy metals and trace elements in twin pregnancy and its relationship with twin growth discordance. Methods: This study involving 60 twin pairs and their mothers was conducted in Zhejiang Province, China, in 2020-2021. The concentration of heavy metals and trace elements in maternal blood, umbilical cord, and placenta were collected at delivery and measured by inductively coupled plasma tandem mass spectrometer. The association of prenatal level with twin growth discordance was evaluated using conditional logistic regression. Results: High levels of heavy metal elements (thallium in maternal blood and umbilical cord blood of larger twins, vanadium in the placenta of larger twins) and trace elements (iodine in the placenta of larger twins) during pregnancy, as well as low levels of heavy metal elements (strontium in the umbilical cord blood of larger twins, strontium and chromium in the umbilical cord blood of smaller twins, strontium in the placenta of larger twins, molybdenum and lead in the placenta of smaller twins and difference of molybdenum in the placenta of twins), are associated with intertwin birthweight discordance. Univariate regression analyses showed a significant effect of gestational age at delivery and eleven trace element data on intertwin birthweight discordance. Multivariable logistic regression analysis with transformed variables as dichotomous risk factors combined with baseline demographic characteristics showed Tl in maternal blood as an independent risk factor. The model constructed by combining Tl in maternal blood (OR = 54.833, 95% CI, 3.839-83.156) with the gestational week (OR = 0.618, 95% CI, 0.463-0.824) had good predictive power for intertwin birthweight discordance (AUC = 0.871). The sensitivity analysis results indicate that the effect of maternal blood thallium on intertwin birthweight discordance is stable and reliable. Conclusion: To our knowledge, ours is the first case-control study to investigate the association between elevated maternal thallium levels before delivery and twin growth discordance.

Association of Thallium with Diabetes Risk among Patients with Hearing Loss: Result from NHANES 2013 to 2018.

To evaluate the correlation between thallium and diabetes risk among participants with hearing loss. This retrospective cohort study extracted related data such as demographic characteristics, lifestyle factors, and laboratory findings from the National Health and Nutrition Examination Survey (NHANES) database (2013-2018). Logistic regression analysis and interaction analysis were adopted to analyze the correlation between thallium and diabetes risk among patients with hearing loss. Then, the restricted cubic spline was employed to assess the nonlinear relationship between thallium and diabetes risk. The receiver operating characteristic curve and decision curve analysis were used to assess the predictive values of 3 multivariate models with or without thallium for diabetes risk. The Delong test was adopted to assess the significant change of the area under the curves (AUCs) upon thallium addition. A total of 425 participants with hearing loss were enrolled in the study: without diabetes group (n = 316) and diabetes group (n = 109). Patients with hearing loss in the diabetes group had significantly lower thallium (P < .05). The thallium was an independent predictor for diabetes risk after adjusting various covariates (P < .05). The restricted cubic spline (RCS) result showed that there was a linear correlation between thallium and diabetes risk (P nonlinear > .05). Finally, the receiver operating characteristic and decision curve analysis results revealed that adding thallium to the models slightly increased the performance in predicting diabetes risk but without significance in AUC change. Thallium was an independent predictor of diabetes risk among patients with hearing loss. The addition of thallium might help improve the predictive ability of models for risk reclassification. However, the conclusions should be verified in our cohort in the future due to the limitations inherent in the NHANES database.

Aggregation, retention and transport of γ-MnO2 nanoparticles in water-saturated porous media: Impact on the immobility of thallium.

Nano-scale Mn oxides can act as effective stabilizers for Tl in soil and sediments. Nevertheless, the comprehensive analysis of the capacity of MnO2 to immobilize Tl in such porous media has not been systematically explored. Therefore, this study investigates the impact of γ-MnO2, a model functional nanomaterial for remediation, on the mobility of Tl in a water-saturated quartz sand-packed column. The mechanisms involved are further elucidated based on the adsorption and aggregation kinetics of γ-MnO2. The results indicate that higher ionic strength (IS) and the presence of ion Ca(II) promote the aggregation of γ-MnO2, resulting from the reduced electrostatic repulsion between particles. Conversely, an increase in pH inhibits aggregation due to enhanced interaction energy. γ-MnO2 significantly influences Tl retention and mobility, with a substantial fraction of γ-MnO2-bound Tl transported through the column. This might be attributed to the high affinity of γ-MnO2 for Tl through ion exchange reactions and precipitation at the surface of γ-MnO2. The mobility of Tl in the sand column is influenced by the γ-MnO2 colloids, exhibiting either inhibition or promotion depending on the pH, IS, and cation type of the solution. In solutions with higher IS and Ca(II), the mobility of Tl decreases as γ-MnO2 colloids tend to aggregate, strain, and block, facilitating colloidal Tl retention in porous media. Although higher pH reduces the mobility of individual Tl, it promotes the mobility of γ-MnO2 colloids, facilitating a substantial fraction of colloidal-form Tl. Consequently, the optimal conditions for stabilizing Tl by γ-MnO2 involve either high IS and low pH or the presence of competitive cations (e.g., Ca(II)). These findings provide new insights into Tl immobilization using MnO2- and Mn oxide-based functional materials, offering potential applications in the remediation of Tl contamination in soil and groundwater.

Cryptic footprint of thallium in soil-plant systems; A review.

The current review highlights the complex behavior of thallium (Tl) in soil and plant systems, offering insight into its hazardous characteristics and far-reaching implications. The research investigates the many sources of Tl, from its natural existence in the earth crust to its increased release through anthropogenic activities such as industrial operations and mining. Soil emerges as a significant reservoir of Tl, with diverse physicochemical variables influencing bioavailability and entrance into the food chain, notably in Brassicaceae family members. Additionally, the study highlights a critical knowledge gap concerning Tl influence on legumes (e.g., soybean), underlining the pressing demand for additional studies in this crucial sector. Despite the importance of leguminous crops in the world food supply and soil fertility, the possible impacts of Tl on these crops have received little attention. As we traverse the ecological complexity of Tl, this review advocates the collaborative research efforts to eliminate crucial gaps and provide solutions for reducing Tl detrimental impacts on soil and plant systems. This effort intends to pave the path for sustainable agricultural practices by emphasizing the creation of Tl-tolerant legume varieties and revealing the complicated dynamics of Tl-plant interactions, assuring the long-term durability of our food systems against the danger of Tl toxicity.

Human health risk assessment associated with the reuse of treated wastewater in arid areas.

Qatar produces more than 850,000 m3/day of highly treated wastewater. The present study aims at characterizing the effluents coming out of three central wastewater treatment plants (WWTPs) of chemical pollutants including metals, metalloids and antibiotics commonly used in the country. Additionally, the study is assessing human health risks associated with the exposure to the treated wastewater (TWW) via dermal and ingestion routes. Although the origin of domestic wastewater is desalinated water (the only source of fresh water), the results show that the targeted parameters in TWW were within the international standards. Concentrations of Cl, F, Br, NO3, NO2, SO4 and PO4, were 389, <0.1, 1.2, 25, <0.1, 346, and 2.8 mg/L, respectively. On the other hand, among all cations, metals and metalloids, only boron (B) was 2.1 mg/L which is higher than the Qatari guidelines for TWW reuse in irrigation of 1.5 mg/L. Additionally, strontium (Sr) and thallium (Tl) were detected with relatively high concentrations of 30 mg/L and 12.5 µg/L, respectively, due to their natural and anthropogenic sources. The study found that the low concentrations of all tested metals and metalloids do not pose any risk to human health. However, Tl presents exposure levels above the 10 % of oral reference dose (HQ = 0.4) for accidental oral ingestion of TWW. The results for antibiotics show that exposure for adults and children to TWW are far below the admissible daily intakes set using minimum therapeutic dose and considering uncertainty factors. Treated wastewater of Qatar can be used safely for irrigation. However, further investigations are still needed to assess microbiological quality.

Selective removal of thallium from water by MnO2-doped magnetic beads: Performance and mechanism study.

Aqueous thallium has posed an increasing threat to environment as human's intensified activities in mining, refining, process and discharge. Remediation on thallium pollution has been of up-most importance to water treatment. In present work, MnO2 and magnetic Fe3O4 have been implanted to sodium alginate (SA) in presence of carboxyl methyl cellulose (CMC), and the resultant beads consisted of SA/CMC/MnO2/Fe3O4 were characterized. The materials were applied to treatment of Tl-contaminated water as adsorbent in lab. The removal results revealed that the adsorption capacity reached 38.8 mg (Tl)·g (beads)-1 and almost 100 % removal efficiency was achieved. The residual Tl was below 0.1 µg·L-1, meeting the discharge standard regulated in China. The kinetic adsorption was better described as a pseudo-second-order and three-step intra-particle diffusion model. Freundlich isotherm was well fitted the experimental data. The absorbent shown an excellent competitive specificity (KTl/M: ∼104!) over common hazardous ions Cu2+, Cd2+, Co2+, Pb2+ and Cr3+, as well as naturally abundant K+ and Na+ (KTl/M: 10-102) in mimic environmental conditions. Regeneration and reusability of the absorbent was also verified by five absorption-desorpotion cycles. XPS results revealed that a redox reaction between Mn4+ with Tl+, and an ion exchange of H+ (-O-Fe) and Tl+ were assumed to be main process for the specific capturing. This study provided an efficient SA/CMC/MnO2/Fe3O4 composite beads that could be a promising adsorbent for Tl-polluted water treatment.

Joint associations among non-essential heavy metal mixtures and nutritional factors on glucose metabolism indexes in US adults: evidence from the NHANES 2011-2016.

Dietary intake can modify the impact of metals on human health, and is also closely related to glucose metabolism in human bodies. However, research on their interaction is limited. We used data based on 1738 adults aged ≥20 years from the National Health and Nutrition Examination Survey 2011-2016. We combined linear regression and restricted cubic splines with Bayesian kernel machine regression (BKMR) to identify metals associated with each glucose metabolism index (P < 0.05 and the posterior inclusion probabilities of BKMR >0.5) in eight non-essential heavy metals (barium, cadmium, antimony, tungsten, uranium, arsenic, lead, and thallium) and glucose metabolism indexes [fasting plasma glucose (FPG), blood hemoglobin A1c (HbA1c) and homeostatic model assessment of insulin resistance (HOMA-IR)]. We identified two pairs of metals associated with glucose metabolism indexes: cadmium and tungsten to HbA1c and barium and thallium to HOMA-IR. Then, the cross-validated kernel ensemble (CVEK) approach was applied to identify the specific nutrient group (nutrients) that interacted with the association. By using the CVEK model, we identified significant interactions between the energy-adjusted diet inflammatory index (E-DII) and cadmium, tungsten and barium (all P < 0.05); macro-nutrients and cadmium, tungsten and barium (all P < 0.05); minerals and cadmium, tungsten, barium and thallium (all P < 0.05); and A vitamins and thallium (P = 0.043). Furthermore, a lower E-DII, a lower intake of carbohydrates and phosphorus, and a higher consumption of magnesium seem to attenuate the positive association between metals and glucose metabolism indexes. Our finding identifying the nutrients that interact with non-essential heavy metals could provide a feasible nutritional guideline for the general population to protect against the adverse effects of non-essential heavy metals on glucose metabolism.

The interpretable machine learning model associated with metal mixtures to identify hypertension via EMR mining method.

There are limited data available regarding the connection between hypertension and heavy metal exposure. The authors intend to establish an interpretable machine learning (ML) model with high efficiency and robustness that identifies hypertension based on heavy metal exposure. Our datasets were obtained from the US National Health and Nutrition Examination Survey (NHANES, 2013-2020.3). The authors developed 5 ML models for hypertension identification by heavy metal exposure, and tested them by 10 discrimination characteristics. Further, the authors chose the optimally performing model after parameter adjustment by Genetic Algorithm (GA) for identification. Finally, in order to visualize the model's ability to make decisions, the authors used SHapley Additive exPlanation (SHAP) and Local Interpretable Model-Agnostic Explanations (LIME) algorithm to illustrate the features. The study included 19 368 participants in total. A best-performing eXtreme Gradient Boosting (XGB) with GA for hypertension identification by 16 heavy metals was selected (AUC: 0.774; 95% CI: 0.772-0.776; accuracy: 87.7%). According to SHAP values, Barium (0.02), Cadmium (0.017), Lead (0.017), Antimony (0.008), Tin (0.007), Manganese (0.006), Thallium (0.004), Tungsten (0.004) in urine, and Lead (0.048), Mercury (0.035), Selenium (0.05), Manganese (0.007) in blood positively influenced the model, while Cadmium (-0.001) in urine negatively influenced the model. Study participants' hypertension associated with heavy metal exposure was identified by an efficient, robust, and interpretable GA-XGB model with SHAP and LIME. Barium, Cadmium, Lead, Antimony, Tin, Manganese, Thallium, Tungsten in urine, and Lead, Mercury, Selenium, Manganese in blood are positively correlated with hypertension, while Cadmium in blood is negatively correlated with hypertension.

Mechanisms of Uptake and Translocation of Thallium in Brassica Vegetables: An X-ray Fluorescence Microspectroscopic Investigation.

Most nonoccupational human exposure to thallium (Tl) occurs via consumption of contaminated food crops. Brassica cultivars are common crops that can accumulate more than 500 µg Tl g-1. Knowledge of Tl uptake and translocation mechanisms in Brassica cultivars is fundamental to developing methods to inhibit Tl uptake or conversely for potential use in phytoremediation of polluted soils. Brassica cultivars (25 in total) were subjected to Tl dosing to screen for Tl accumulation. Seven high Tl-accumulating varieties were selected for follow-up Tl dosing experiments. The highest Tl accumulating Brassica cultivars were analyzed by synchrotron-based micro-X-ray fluorescence to investigate the Tl distribution and synchrotron-based X-ray absorption near-edge structure spectroscopy (XANES) to unravel Tl chemical speciation. The cultivars exhibited different Tl tolerance and accumulation patterns with some reaching up to 8300 µg Tl g-1. The translocation factors for all the cultivars were >1 with Brassica oleracea var. acephala (kale) having the highest translocation factor of 167. In this cultivar, Tl is preferentially localized in the venules toward the apex and along the foliar margins and in minute hot spots in the leaf blade. This study revealed through scanning electron microscopy and X-ray fluorescence analysis that highly Tl-enriched crystals occur in the stoma openings of the leaves. The finding is further validated by XANES spectra that show that Tl(I) dominates in the aqueous as well as in the solid form. The high accumulation of Tl in these Brassica crops has important implications for food safety and results of this study help to understand the mechanisms of Tl uptake and translocation in these crops.

Effects of Acute and Subchronic Waterborne Thallium Exposure on Ionoregulatory Enzyme Activity and Oxidative Stress in Rainbow Trout (Oncorhynchus mykiss).

The mechanisms of acute (96-hour) and subchronic (28-day) toxicity of the waterborne trace metal thallium (Tl) to rainbow trout (Oncorhynchus mykiss) were investigated. Specifically, effects on branchial and renal ionoregulatory enzymes (sodium/potassium adenosine triphosphatase [ATPase; NKA] and proton ATPase) and hepatic oxidative stress endpoints (protein carbonylation, glutathione content, and activities of catalase and glutathione peroxidase) were examined. Fish (19-55 g) were acutely exposed to 0 (control), 0.9 (regulatory limit), 2004 (half the acute median lethal concentration), or 4200 (acute median lethal concentration) µg Tl L-1 or subchronically exposed to 0, 0.9, or 141 (an elevated environmental concentration) µg Tl L-1 . The only effect following acute exposure was a stimulation of renal H+ -ATPase activity at the highest Tl exposure concentration. Similarly, the only significant effect of subchronic Tl exposure was an inhibition of branchial NKA activity at 141 µg Tl L-1 , an effect that may reflect the interaction of Tl with potassium ion handling. Despite significant literature evidence for effects of Tl on oxidative stress, there were no effects of Tl on any such endpoint in rainbow trout, regardless of exposure duration or exposure concentration. Elevated basal levels of antioxidant defenses may explain this finding. These data suggest that ionoregulatory perturbance is a more likely mechanism of Tl toxicity than oxidative stress in rainbow trout but is an endpoint of relevance only at elevated environmental Tl concentrations. Environ Toxicol Chem 2024;43:87-96. © 2023 SETAC.

High geogenic soil thallium shows limited impact on bacterial community.

Thallium (Tl) is a highly toxic trace metal, included in the US EPA list of priority pollutants. Even though its toxicity is potentially higher or comparable to Cd or Hg, its environmental impact is largely unknown. Despite its toxicity, only a few recent studies are mapping the impact of recently introduced Tl on soil microbial communities, namely in agricultural systems but no studies focus on its long term effect. To complement the understanding of the impact of Tl on soil, this study aims to describe the influence of extremely high naturally occurring Tl concentration (50 mg/kg of potentially bioavailable Tl) on soil microbial communities. Our investigation concentrated on samples collected at Buus (Erzmatt, Swiss Jura, Switzerland), encompassing forest and meadow soil profiles of the local soil formed on hydrothermally mineralized dolomite rock, which is naturally rich in Tl. The soil profiles showed a significant proportion of potentially bioavailable Tl. Yet, even this high concentration of Tl has a limited impact on the richness of the soil bacterial community. Only the meadow soil samples show a reduced richness compared to control samples. Furthermore, our analysis of geogenic Tl contamination in the region unveiled a surprising finding: compared to other soils of Switzerland and in stark contrast to soils affected by recent mining activities, the structure of the bacterial community in Buus remained relatively unaffected. This observation highlights the unique ability of soil microbial communities to withstand extreme Tl contamination. Our study advances the understanding of Tl's environmental impact and underscores the resilience of soil microbes in the face of severe long-term contamination.

Production of pharmaceutical grade [201Tl]Thallous chloride using 30 MeV cyclotron.

Multiple patient doses of [201Tl]TlCl has been produced using electrodeposited enriched 203Tl in 30 MeV cyclotron (Cyclone-30) with 28 MeV proton energy at 50 µA beam current for 8 h. Ion Exchange Column Chromatography (IECC) and liquid-liquid extraction has been employed for semi-automated radiochemical separation and purification of produced [201Tl]TlCl. The produced [201Tl]TlCl was used in coronary artery disease (CAD) patients.

Thallium content in vegetables and derivation of threshold for safe food production in soil: A meta-analysis.

Soil thallium (Tl) pollution is a serious environmental problem, and vegetables are the primary pathway for human exposure to Tl. Therefore, it is important to investigate the characteristics of soil Tl uptake by vegetables. In this study, the meta-analysis approach was first applied to explore the relationship between Tl content in vegetables and soil environment, as well as key factors influencing soil physical-chemical properties, and to derive soil thresholds for Tl. The results indicated that various types of vegetables have different capabilities for Tl accumulation. Vegetables from contaminated areas showed high Tl accumulation, and the geomean Tl content in different types of vegetables was in the following order: leafy > root-stalk > solanaceous vegetables. Taro and kale had significantly higher capability to accumulate soil Tl among the 35 species studied, with Tl bioconcentration factor values of 0.060 and 0.133, respectively. Pearson correlation analysis and meta-analysis revealed that the Tl content in vegetables was significantly correlated with soil pH and Tl content in soil. The linear predictive model for Tl accumulation in vegetables based on soil Tl content described the data well, and the fitting coefficient R2 increased with soil pH value. According to potential dietary toxicity, the derived soil Tl thresholds for all, leafy and root-stalk vegetables increased with an increase in soil pH, and were in the range of 1.46-6.72, 1.74-5.26 and 0.92-6.06 mg/kg, respectively. The soil Tl thresholds for kale, lettuce and carrot were in the range of 0.24-4.89, 2.94-3.32 and 3.77-14.43 mg/kg, respectively. Ingestion of kale, beet, sweet potato, potato, taro, pepper, turnip, Chinese cabbage, eggplant and carrot poses potential health risks. The study provides scientific guidance for vegetable production in Tl-contaminated areas and can help with the selection of vegetable species suitable for avoiding the absorption of Tl from contaminated soil.

MnFe2O4-biochar decreases bioavailable fractions of thallium in highly acidic soils from pyrite mining area.

The prevalence of toxic element thallium (Tl) in soils is of increasing concern as a hidden hazard in agricultural systems and food chains. In the present work, pure biochar (as a comparison) and jacobsite (MnFe2O4)-biochar composite (MFBC) were evaluated for their immobilization effects in Tl-polluted agricultural soils (Tl: ∼10 mg/kg). Overall, MFBC exhibited an efficient effect on Tl immobilization, and the effect was strengthened with the increase of amendment ratio. After being amended by MFBC for 15 and 30 days, the labile fraction of Tl in soil decreased from 1.55 to 0.97 mg/kg, and from 1.51 to 0.88 mg/kg, respectively. In addition, pH (3.05) of the highly acidic soil increased to a maximum of 3.97 after the immobilization process. Since the weak acid extractable and oxidizable Tl were the preponderantly mitigated fractions and displayed a negative correlation with pH, it can be inferred that pH may serve as one of the most critical factors in regulating the Tl immobilization process in MFBC-amended acidic soils. This study indicated a great potential of jacobsite-biochar amendment in stabilization and immobilization of Tl in highly acidic and Tl-polluted agricultural soils; and it would bring considerable environmental benefit to these Tl-contaminated sites whose occurrence has significantly increased in recent decades near the pyrite or other sulfide ore mining and smelting area elsewhere.