Thallium exposure at low concentration leads to early damage on multiple organs in children: A case study followed-up for four years

Thallium reabsorption via NKCC2 causes severe acute kidney injury with outer medulla-specific calcium crystal casts in rats

Thallium (Tl) is one of the most toxic heavy metals, associated with accidental poisoning and homicide. It causes acute and chronic systemic diseases, including gastrointestinal and cardiovascular diseases and kidney failure. However, few studies have investigated the mechanism by which Tl induces acute kidney injury (AKI). This study investigated the toxic effects of Tl on the histology and function of rat kidneys using biochemical and histopathological assays after intraperitoneal thallium sulfate administration (30 mg/kg). Five days post-administration, rats exhibited severely compromised kidney function. Low-vacuum scanning electron microscopy revealed excessive calcium (Ca) deposition in the outer medulla of Tl-loaded rats, particularly in the medullary thick ascending limb (mTAL) of the loop of Henle. Tl accumulated in the mTAL, accompanied by mitochondrial dysfunction in this segment. Tl-loaded rats showed reduced expression of kidney transporters and channels responsible for Ca2+ reabsorption in the mTAL. Pre-administration of the Na-K-Cl cotransporter 2 (NKCC2) inhibitor furosemide alleviated Tl accumulation and mitochondrial abnormalities in the mTAL. These findings suggest that Tl nephrotoxicity is associated with preferential Tl reabsorption in the mTAL via NKCC2, leading to mTAL mitochondrial dysfunction and disrupted Ca2+ reabsorption, culminating in mTAL-predominant Ca crystal deposition and AKI. These findings on the mechanism of Tl nephrotoxicity may contribute to the development of novel therapeutic approaches to counter Tl poisoning. Moreover, the observation of characteristic Ca crystal deposition in the outer medulla provides new insights into diagnostic challenges in Tl intoxication.

The associations of the concentrations of toxic metals (including metalloid) in blood and follicular fluid with the risk of diminished ovarian reserve

BACKGROUND

Diminished ovarian reserve (DOR), a triggering factor for female infertility, affects 10% ∼ 35% of women of reproductive age. It is still unclear whether exposure to toxic metals (including metalloid) is associated with DOR risk, especially with respect to their relationships with the clinical phenotypes of DOR.

METHODS

A case-control study including 439 patients was conducted, and Ba, Ni, As, Tl, Cd, Pb, Hg, Al and Cr levels in BL and FF were measured. Subsequent analyses were focused on Ba, Ni, As and Tl, which had the highest weights in the associations of the nine toxic metals (including metalloid) with DOR risk, by integrating weighted quantile sum (WQS) regression and bayesian kernel machine regression (BKMR) models. Conditional logistic regression models and BKMR models were used to assess the individual and combined effects of Ba, Ni, As and Tl exposures on DOR risk. Multiple linear regression models were used to investigate the relationships between toxic metal (including metalloid) levels in BL and FF and the clinical characteristics of DOR.

RESULTS

The levels of Ba [second vs. lowest tertile: adjusted odds ratio (aOR) and 95 % confidence interval (CI) = 1.97 (1.13, 3.44); highest vs. lowest tertile: aOR (95 % CI) = 2.38 (1.32, 4.26)], Ni [highest vs. lowest tertile: aOR (95 % CI) = 2.59 (1.45, 4.65)] and As [highest vs. lowest tertile: aOR (95 % CI) = 1.96 (1.18, 3.25)] in BL, and Ba [highest vs. lowest tertile: aOR (95 % CI) = 4.60 (1.68, 12.61)] in FF were significantly associated with a higher risk of DOR, respectively. The significantly positive combined effect of the four toxic metals (including metalloid) on DOR risk was exhibited when their BL levels exceeded the 25th percentile compared with their median levels. Among these, As (0.9822) and Ba (0.9704) were the primary contributors to this relationship. Similarly, this finding was confirmed by the statistical results from FF samples, with a linear positive correlation between combined exposure and DOR risk, where Ba (0.9440) was the primary contributor. Finally, elevated levels of Ba, Ni, and As in BL and Ba in FF were significantly linked to the higher follicle-stimulating hormone (FSH) levels. The levels of Ba in BL and FF, as well as As in BL, were significantly associated with the lower luteinizing hormone (LH)/FSH ratio values.

CONCLUSION

Overall, the results of this study indicate that elevated levels of Ba, Ni, As and Tl are associated with a higher risk of DOR, whether individually or in combination, and that Ba levels in BL and FF are stable contributors. In addition, exposure to Ba, Ni, As and Tl is linked to various clinical phenotype parameters of DOR. Further research is needed to confirm these associations and to identify potential mechanisms involved.

Association of Thallium Exposure with Decreased Renal Function among Chinese Adults - China, 2017-2018

What is already known about this topic?

Thallium (Tl) is significantly more toxic than heavy metals such as lead, cadmium, and mercury. However, previous studies examining the relationship between Tl exposure and the risk of chronic kidney disease (CKD) have yielded inconsistent results.

What is added by this report?

The study demonstrated that elevated urinary Tl levels were associated with a higher prevalence of CKD and a reduced estimated glomerular filtration rate (eGFR), particularly among older adults. These findings were consistent in the restricted cubic spline (RCS) analyses.

What are the implications for public health practice?

This study identified Tl as a risk factor for decreased renal function, underscoring the need to enhance surveillance of Tl to mitigate the disease burden of CKD.

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.

Thallium - poisoner's poison: An overview and review of current knowledge on the toxicological effects and mechanisms

Thallium (Tl) is one of the most toxic metals and its historic use in homicides has led it to be known as "the poisoner's poison." This review summarizes the methods for identifying Tl and determining its concentrations in biological samples in recently reported poisoning cases, as well as the toxicokinetics, toxicological effects, toxicity mechanisms, and detoxication methods of Tl. Recent findings regarding Tl neurotoxicological pathways and toxicological effects of Tl during pregnancy are also presented. Confirmation of elevated Tl concentrations in blood, urine, or hair is indispensable for diagnosing Tl poisoning. The kidneys show the highest Tl concentration within 24 h after ingestion, while the brain shows the highest concentration thereafter. Tl has a very slow excretion rate due to its large distribution volume. Following acute exposure, gastrointestinal symptoms are observed at an early stage, and neurological dysfunction is observed later: Tl causes the most severe damage in the central nervous system. Alopecia and Mees' lines in the nails are observed within 1 month after Tl poisoning. The toxicological mechanism of Tl is considered to be interference of vital potassium-dependent processes with Tl+ because its ionic radius is similar to that of K+, as well as inhibition of enzyme reactions by the binding of Tl to -SH groups, which disturbs vital metabolic processes. Tl toxicity is also related to reactive oxygen species generation and mitochondrial dysfunction. Prussian blue is the most effective antidote, and metallothionein alone or in combination with Prussian blue was recently reported to have cytoprotective effects after Tl exposure. Because Tl poisoning cases are still reported, early determination of Tl in biological samples and treatment with an antidote are essential.

Association of urinary thallium with hypertension in children and adolescents aged 8-17 years: NHANES 2005-2018

Hypertension is a key risk factor for cardiovascular disease (CVD). Thallium is a highly toxic metal that exists in all aspects of our lives and can cause damage to human health. The aim of this study was to identify the potential correlation between urinary thallium (U-Tl) and hypertension in American youth aged 8-17 years. The National Health and Nutritional Examination Survey (NHANES) database was mined for cross-sectional information on 2295 American children and adolescents aged 8-17 years. Inductively coupled plasma mass spectrometry (ICP-MS) was utilized to measure U-Tl levels, and the results were categorized into four quartiles (Q1-Q4). Logistic generalized linear models and unweighted restricted cubic spline (RCS) regression were used to investigate the relationship between U-Tl and hypertension. After adjusting for covariates, the odds ratios (ORs) at 95% confidence intervals (CIs) for hypertension prevalence in the 2nd, 3rd, and 4th quartiles were 0.43 (0.22-0.81), 0.54 (0.29-0.99), and 0.43 (0.22-0.81), when compared to the lowest quartile (P for trend = 0.024). RCS plot showed a negative linear correlation between log2-transformed U-Tl levels and hypertension (P for non-linearity = 0.869). Subgroup analysis based on sex indicated a statistically significant link between U-Tl and hypertension in male (P < 0.05). There is a negative linear relationship between U-Tl and hypertension in American children and adolescents aged 8-17 years with low thallium exposure. Due to the nature of cross-sectional studies, further studies are necessary to validate our conclusions and elucidate possible mechanisms.

A novel application of thallium isotopes in tracing metal(loid)s migration and related sources in contaminated paddy soils

Thallium (Tl) is a highly toxic heavy metal, which is harmful to plants and animals even in trace amounts. Migration behaviors of Tl in paddy soils system remain largely unknown. Herein, Tl isotopic compositions have been employed for the first time to explore Tl transfer and pathway in paddy soil system. The results showed considerably large Tl isotopic variations (ε²⁰⁵Tl = -0.99 ± 0.45 ~ 24.57 ± 0.27), which may result from interconversion between Tl(I) and Tl(III) under alternative redox conditions in the paddy system. Overall higher ε²⁰⁵Tl values of paddy soils in the deeper layers were probably attributed to abundant presence of Fe/Mn (hydr)oxides and occasionally extreme redox conditions during alternative dry-wet process which oxidized Tl(I) to Tl(III). A ternary mixing model using Tl isotopic compositions further disclosed that industrial waste contributed predominantly to Tl contamination in the studied soil, with an average contribution rate of 73.23%. All these findings indicate that Tl isotopes can be used as an efficient tracer for fingerprinting Tl pathway in complicated scenarios even under varied redox conditions, providing significant prospect in diverse environmental applications.

Thallium exposure interfered with heart development in embryonic zebrafish (Danio rerio): From phenotype to genotype

Thallium (Tl) is a rare trace metal element but increasingly detected in wastewater produced by coal-burning, smelting, and more recently, high-tech manufacturing industries. However, the adverse effects of Tl, especially cardiotoxicity, on aquatic biota remain unclear. In this study, zebrafish model was used to elucidate the effects and mechanisms of Tl(I) cardiotoxicity in developing embryos. Exposure of embryonic zebrafish to low-dose Tl(I) (25-100 μg/L) decreased heart rate and blood flow activity, and subsequently impaired swim bladder inflation and locomotive behavior of larvae. Following high-level Tl(I) administration (200-800 μg/L), embryonic zebrafish exhibited pericardial edema, incorrect heart looping, and thinner myocardial layer. Based on RNA-sequencing, Tl(I) altered pathways responsible for protein folding and transmembrane transport, as well as negative regulation of heart rate and cardiac jelly development. The gene expression of nppa, nppb, ucp1, and ucp3, biomarkers of cardiac damage, were significantly upregulated by Tl(I). Our findings demonstrate that Tl(I) at environmentally relevant concentrations interfered with cardiac development with respect to anatomy, function, and transcriptomic alterations. The cardiotoxic mechanisms of Tl(I) provide valuable information in the assessment of Tl-related ecological risk in freshwater environment.

Tl(I) and Tl(III) induce reticulum stress in MDCK cells

The effects of the exposure of proliferating MDCK cells to thallium [Tl(I) or Tl(III)] on cell viability and proliferation were investigated. Although Tl stopped cell proliferation, the viability was >95%. After 3h, two autophagy markers (SQSTM-1 expression and LC3β localization) were altered, and at 48h increased expression of SQSTM-1 (60%) and beclin-1 (50-100%) were found. At 24h, the expression of endoplasmic reticulum (ER) stress markers ATF-6 and IRE-1 were increased in 100% and 150%, respectively, accompanied by XBP-1 splicing and nuclear translocation. At 48h, major ultrastructure abnormalities were found, including ER enlargement and cytoplasmic vacuolation which was not prevented by protein synthesis inhibition. Increased PHB (85% and 40% for Tl(I) and Tl(III), respectively) and decreased β-tubulin (45%) expression were found which may be related to the promotion of paraptosis. In summary, Tl(I) and Tl(III) promoted ER stress and probably paraptosis in MDCK cells, impairing their proliferation.

Variation in the burden and chemical forms of thallium in non-detoxified tissues of tilapia fish (Oreochromis niloticus) from waterborne exposure

Thallium (Tl) is highly toxic to aquatic ecosystems, but information about its concentration and distribution characteristics in different fish tissues is limited. In this study, juvenile tilapia (Oreochromis niloticus) were exposed to Tl solutions with different sub-lethal concentrations for 28 days, and the Tl concentrations and distribution patterns in the fish non-detoxified tissues (gills, muscle, and bone) were analyzed. The Tl chemical form fractions, Tl-ethanol, Tl-HCl, and Tl-residual, corresponding to easy, moderate, and difficult migration fraction, respectively, in the fish tissues were obtained by sequential extractant approach. The Tl concentrations of different fractions and total burden were determined using graphite furnace atomic absorption spectrophotometry. Exposure-concentration effect determined the Tl burden in the fish tissues. The average Tl-total concentration factors were 360, 447, and 593 in the bone, gills, and muscle, respectively, and the limited variation during the exposure period indicates that tilapia have a strong ability to self-regulate and achieve Tl homeostasis. However, Tl fractions varied in tissues, and the Tl-HCl fraction dominated in the gills (60.1%) and bone (59.0%), switchover Tl-ethanol fraction dominated in the muscle (68.3%). This study has shown that Tl can be easily taken up by fish during 28-days-period and largely distributed in non-detoxified tissues especially muscle, in which concurrent risks of high Tl-total burden and high levels of Tl in the form of easy migration fraction, posing possible risks to public health.

Association between urinary metal concentrations and abnormal estimated glomerular filtration rate in Chinese community-dwelling elderly: Exploring the mediating effect of triglycerides

BACKGROUND

Environmental metal exposure is associated with elevated triglycerides (TG) and the development of chronic kidney disease (CKD). However, the relationship between metal exposure and glomerular filtration rate (GFR) remains uncertain, and the mediating effect of TG between the two is unclear.

METHODS

This study measured the concentrations of 14 metals in urine samples from 3752 elderly people in the community. The most relevant metals were screened by least absolute shrinkage and selection operator (LASSO) regression. The relationship between combined exposure to multiple metals and abnormal estimated glomerular filtration rate (eGFR) was explored using multivariate logistic regression analysis and Bayesian kernel machine regression (BKMR) analysis. Generalized linear regression models and the Karlson-Holm-Green (KHB) method were used to assess the mediating effects of TG.

RESULTS

In the single-metal model, calcium (Ca), iron (Fe), selenium (Se), strontium (Sr), and thallium (Tl) showed significant negative correlations with the prevalence of abnormal eGFR (all P < 0.05). In the multi-metals model, Ca, Se, and Tl continued to show significant negative correlations, while vanadium (V) and zinc (Zn) showed significant positive correlations with abnormal eGFR (all P < 0.05). The BKMR model showed a negative joint effect of the mixture of Ca, V, Zn, Se, and Tl on the prevalence of abnormal eGFR. The generalized linear regression model showed a significant positive correlation between the concentrations of Ca (β = 0.07), Zn (β = 0.07), Se (β = 0.09), and TG levels (all P < 0.05). In the mediation analysis, TG masked a 4.30% and 5.21% correlation between Ca and Se and the prevalence of eGFR abnormalities, respectively.

CONCLUSIONS

Urinary concentration of multiple metals is significantly associated with eGFR abnormalities, and Ca, and Se may be among the potential protective factors. TG masked some of the protective effects of Ca and Se.

Thallium exposure induces changes in B and T cell generation in mice

Thallium (Tl) is a high-priority toxic metal that poses a severe threat to human health. The toxicity characteristics induced by Tl have been partially discussed. However, the immunotoxic effects of Tl exposure have remained largely unexplored. Our findings demonstrated that 50 ppm of Tl exposure for one week induced severe weight loss in mice, which was accompanied by appetite suppression. Moreover, although Tl exposure did not induce significant pathological damage to skeletal muscle and bone, Tl inhibited the expression of B cell development-related genes in the bone marrow. Additionally, Tl exposure increased B cell apoptosis and reduced its generation in the bone marrow. Analysis of B cells in the blood indicated that the percentage of B-2 cells decreased significantly, whereas B-2 cell proportions in the spleen did not. The percentage of CD4⁺ T cells in the thymus increased significantly, and the proportion of CD8⁺ T cells did not. Furthermore, although the proportion of the total CD4⁺ and CD8⁺ T cells was not significantly altered in the blood and spleen, Tl exposure promoted the migration of naïve CD4⁺ T cells and recent thymic emigrants (RTEs) from the thymus to the spleen. These results suggest that Tl exposure can affect B and T cell generation and migration, which provides new evidence for Tl-induced immunotoxicity.

Thallium(III) exposure alters diversity and co-occurrence networks of bacterial and fungal communities and intestinal immune response along the digestive tract in mice

The gut microbiota, which includes fungi and bacteria, plays an important role in maintaining gut health. Our previous studies have shown that monovalent thallium [Tl(I)] exposure is associated with disturbances in intestinal flora. However, research on acute Tl(III) poisoning through drinking water and the related changes in the gut microbiota is insufficient. In this study, we showed that Tl(III) exposure (10 ppm for 2 weeks) reduced the alpha diversity of bacteria in the ileum, colon, and feces of mice, as well as the alpha diversity of fecal fungi. In addition, principal coordinate analysis showed that Tl(III) exposure had little effect on the bacterial and fungal beta diversity. LEfSe analyses revealed that Tl(III) exposure altered the abundance of intestinal bacteria in the digestive tract and feces. Moreover, Tl(III) exposure had little effect on fungal abundance in the ileum, cecum, and colon, but had a considerable effect on fungal abundance in feces. After Tl(III) exposure, the fungal composition was more disrupted in feces than in the intestinal tract, suggesting that feces can serve as a representative of the gut mycobiota in Tl(III) exposure studies. Intra-kingdom network analyses showed that Tl(III) exposure affected the complexity of bacterial-bacterial and fungal-fungal co-occurrence networks along the digestive tract. The bacterial-fungal interkingdom co-occurrence networks exhibited increased complexity after Tl(III) exposure, except for those in the colon. Additionally, Tl(III) exposure altered the intestinal immune response. These results reveal the perturbation in gut bacterial and fungal diversity, abundance, and co-occurrence network complexity, as well as the gut immune response, caused by Tl(III) exposure.

Zwitterionic ammonium-sulfonato grafted cellulose for efficient thallium removal and adsorption mechanism study

Thallium (Tl) has posed serious impacts on human being concerning increasingly serious pollution in aqueous environments. However, little information on removal method than conventional heavy metals have been available. In the present work, zwitterionic N-(3-sulfonato-1-propyl)-N,N-dimethylammonium grafted cellulose fibre (DMAE-PS) has been fabricated. The chemical component, thermal stability and surface properties of as-prepared materials are identified by FT-IR, elemental analysis, TGA, XRD, BET and SEM. DMAE-PS is shown to be very efficient for removing Tl(I) from water samples with a loading capacity of 274.7 mg (Tl(I))·g^-1 (DMAE-PS)_, representing one of the best performances among bio-mass derived materials. The adsorption is consistent with the Freundlich model following a pseudo-second order (K₂ = 4.36 × 10^-4 g·mg^-1·min^-1, R² = 0.999) and two-step intra-particle diffusion kinetics. The selectivity towards Tl(I) is also remarkably, 1-2 orders (distribution ratio K_Tl/M = 14.85-289.29) of magnitude larger than competing metals (Zn²⁺, Cr³⁺, Mn²⁺, Cu²⁺ and Cd²⁺). The SEM, XPS and UV-visible spectrum collectively reveal that -SO₃^--Tl(I) ionic interaction is probably the main driving force for specific adsorption, which shows a high stability against pH variation. The fabricated DMAE-PS is a sustainable bio-adsorbent with synthetic availability, high removing capacity and strong selectivity, therefore, potentially feasible in treatment of Tl(I) polluted environmental samples.

Thallium(I) exposure perturbs the gut microbiota and metabolic profile as well as the regional immune function of C57BL/6 J mice

Intestinal microbes regulate the development of diseases induced by environmental exposure. Thallium (Tl) is a highly toxic heavy metal, and its toxicity is rarely discussed in relation to gut microbes. Herein, we showed that Tl(I) exposure (10 ppm for 2 weeks) affected the alpha diversity of bacteria in the ileum, colon, and feces, but had little effect on the beta diversity of bacteria through 16S rRNA sequencing. LEfSe analysis revealed that Tl(I) exposure changed the abundance of intestinal microbiota along the digestive tract. Cecum metabolomic detection and analysis showed that Tl(I) exposure altered the abundance and composition of metabolites. In addition, the Kyoto Encyclopaedia of Genes and Genomes (KEGG) enrichment analysis revealed that Tl(I) exposure impaired amino acid, lipid, purine metabolism, and G protein-coupled receptor signalling pathways. A consistency test revealed a strong correlation, and a Pearson's correlation analysis showed an extensive interaction, between microorganisms and metabolites. Analysis of the intestinal immunity revealed that Tl(I) exposure suppressed the immune responses, which also had regional differences. These results identify the perturbation of the intestinal microenvironment by Tl exposure and provide a new explanation for Tl toxicity.

Thallium(I and III) exposure leads to liver damage and disorders of fatty acid metabolism in mice

Thallium (Tl), a highly toxic and priority pollutant heavy metal, exposure can damage mitochondria and disrupt their function. The liver is the central organ that controls lipid homeostasis and contains a large number of mitochondria. So far, there is no study investigating the effects of Tl exposure on hepatic fatty acid metabolism. Here, we showed that 10 ppm of Tl(I) and Tl(III) exposures for two weeks did not significantly affect the body weight and water/food intake in mice. However, it decreased the ratio of liver/weight and induced hepatic sinus congestion and hepatocyte necrosis. Inductively coupled plasma-mass spectrometry (ICP-MS) analysis revealed Tl accumulation in the liver. Gas chromatography-mass spectrometry (GC-MS) results showed that Tl(I) exposure significantly increased hepatic C18:0 concentration, while significantly decreased the concentrations of C16:1n-7, C20:1n-9, C18:3n-6, and C20:2n-9. Tl(III) exposure significantly reduced hepatic concentrations of C20:0, C22:0, C20:1n-9, C18:3n-6, and C20:3n-6. In addition, Tl(I) exposure upregulated the genes related to antioxidation (HO-1, GPX1, and GPX4), fatty acid synthesis (FADS2 and Elovl2), and fatty acid oxidation pathway (PPARα, ACADM, ACADVL, ACAA2, and CPT1A) in the liver. Tl(III) exposure did not significantly affect the transcript levels of liver antioxidative/metabolic enzymes and fatty acid synthesis-related genes, but upregulated fatty acid oxidation pathway-related genes (CYP4A10 and CPT1A). These results suggest that Tl(I) and Tl(III) exposures can cause liver damage and disrupt hepatic fatty acid metabolism, which provide new insights into Tl exposure-induced energy depletion from the perspective of fatty acid metabolism.

Effect of maternal thallium exposure in early pregnancy on the risk of preterm birth

Human activities have significantly increased the release of thallium (Tl) to the environment. However, the study of the relationship between maternal Tl exposure during pregnancy and the risk of preterm birth (PTB) is scarce so far. We aimed to investigate the association between Tl exposure in early pregnancy and the risk of PTB. A total of 2104 pregnant women from the Tongji Maternal and Child Health Cohort (TMCHC) in Wuhan, China were enrolled in the analysis. We collected the urine samples in early pregnancy (< 20 weeks) and inductively coupled plasma mass spectrometry (ICP-MS) was used to detect urinary Tl levels. The association between Tl levels and the risk of PTB was evaluated by an unconditional logistic regression. The median and geometric mean values of Tl levels were 0.35 μg/L (0.47 μg/g creatinine) and 0.33 μg/L (0.47 μg/g creatinine), respectively. Compared with the lowest tertile of Tl levels (≤ 0.37 μg/g creatinine), the highest tertile (> 0.57 μg/g creatinine) was associated with an increased risk of PTB with an adjusted odds ratio (OR) of 2.11 (95% confidence interval (CI): 1.08, 4.12). Stratified analyses showed an elevated risk of PTB related to the highest tertile of Tl levels for male newborns. After excluding women with miss covariate information, gestational diabetes mellitus, pregnancy-induced hypertension, reporting fish intake, or exposed to smoke, the association remained stable. Our results suggested that maternal Tl exposure during early pregnancy was positively associated with the risk of PTB, and Tl exposure may have a sex-specific effect on PTB.

Transformation and fate of thallium and accompanying metal(loid)s in paddy soils and rice: A case study from a large-scale industrial area in China

Thallium (Tl) is an extremely toxic metal, while its occurrence and fate in paddy soil environment remain understudied. Herein, the enrichment and migration mechanisms and potential health risks of Tl and metal(loid)s were evaluated in paddy soils surrounding an industrial park utilizing Tl-bearing minerals. The results showed that Tl contamination was evident (0.63-3.16 mg/kg) in the paddy soils and Tl was generally enriched in root of rice (Oryza sativa L.) with a mean content of 1.27 mg/kg. A remarkably high level of Tl(III) (30-50%) was observed in the paddy soils. Further analyses by STEM-EDS and XPS indicated that Tl(I) in the paddy soils was jointly controlled by adsorption, oxidation, and precipitation of Fe/Mn(hydr)oxide (e.g. hematite and birnessite), which might act as important stabilization mechanisms for inhibiting potential Tl uptake by rice grains. The health quotient (HQ) values indicated a potentially high Tl risk for inhabitants via consumption of the rice grains. Therefore, it is critical to establish effective measures for controlling the discharge of Tl-containing waste and wastewater from different industrial activities to ensure food safety in the rice paddy soils.

Prenatal serum thallium exposure and cognitive development among preschool-aged children: A prospective cohort study in China

Thallium, a highly toxic heavy metal and priority pollutant, has been widely reported to cause neurodevelopmental toxicity in animals. However, accessible epidemiological studies concerning the neurodevelopmental toxicity of early-life thallium exposure in humans are limited. In a prospective birth cohort including 2164 mother-child pairs, we explored the effect of prenatal serum thallium exposure on cognitive development among preschool-aged children born in Ma'anshan, Anhui, China. Serum thallium concentrations were measured in the first trimester, second trimester, third trimester, and cord blood by inductively coupled plasma mass spectrometry (ICP-MS). Child cognitive development was appraised by the Chinese version of the Wechsler Preschool and Primary Scale of Intelligence-Fourth Edition (WPPSI-IV) at 4.5 years old. Multiple informants generalized estimating equations (GEEs) were fit to jointly estimate the association between the four repeated measurements of thallium concentrations and the preschool-aged children's cognitive test scores. After adjusting for potential confounders, the visual spatial index (VSI) was 1.45 points lower in the highest tertile of serum thallium during the first trimester than in the lowest tertile (p for trend = 0.04). Moreover, children in the highest tertile of serum thallium during the third trimester had a significantly lower full-scale intelligence quotient (FSIQ) (β = -1.51, 95% CI: -2.68, -0.35), VSI (β = -1.79, 95% CI: -3.16, -0.42), fluid reasoning index (FRI) (β = -1.41, 95% CI: -2.73, -0.10), and processing speed index (PSI) (β = -1.47, 95% CI: -2.71, -0.24) scores than the children in the lowest tertile. When performing stratified analysis by child sex, the associations of first- and third-trimester thallium concentrations with cognitive test scores were more prominent in boys than in girls. Our findings revealed that maternal serum thallium exposure during the first and third trimesters, but not other periods, had detrimental effects on preschoolers' cognitive development, and these effects showed sex differences.

The associations between urinary metals and metal mixtures and kidney function in Chinese community-dwelling older adults with diabetes mellitus

BACKGROUND

Previous studies have found associations between single toxic metals, such as arsenic and cadmium, and kidney function in adults with diabetes. However, studies with regards to other metals and metal mixtures are still limited.

OBJECTIVE

Our study aimed to investigate the associations between urinary concentrations of 5 selected metals and metal mixtures and kidney function using a sample of older adults with diabetes mellitus in Chinese communities.

METHODS

In a sample of older adults (n = 5186), 592 eligible subjects were included in this study. Urinary concentrations of 5 metals, i.e., arsenic (As), cadmium (Cd), vanadium (V), cobalt (Co), and thallium (Tl), were measured by inductively coupled plasma mass spectrometer (ICP-MS). Estimated glomerular filtration rate (eGFR) was calculated and dichotomized into indicator of chronic kidney disease (CKD). Logistic analysis and Bayesian kernel machine regression (BKMR) were used to explore the associations between single metals and metal mixtures and CKD, respectively.

RESULTS

Urinary levels of As and V were positively correlated with CKD (OR=2.37, 95% CI: 1.31-4.30 for As; OR=2.24, 95% CI: 1.25-4.03 for V), when compared the 4th quartile with the 1st quartile. After adjustment for potential confounders, the significant association between As and CKD still existed (OR=2.73, 95% CI: 1.23-6.07). BKMR analyses showed strong linear positive associations between As and V and CKD. Higher urinary levels of the mixture were significantly associated with higher odds of CKD in a dose-response pattern. As and V showed the highest posterior inclusion probabilities.

CONCLUSION

Urine As and V were positively associated with CKD in older adults with diabetes mellitus, separately and in a mixture. The metals mixture showed a linear dose-response association with the odds of CKD. The analyses of mixtures, rather than of single metals, may provide a real-world perspective on the relationship between metals and kidney function.

Toxic effects of thallium acetate by acute exposure to the nematode C. elegans

BACKGROUND

Thallium (Tl) is a toxic metalloid and an emerging pollutant due to electronic devices and dispersal nearby base-metal mining. Therefore, Tl poses a threat to human health and especially the long-term impact on younger individuals exposed is still unknown. This study aimed to evaluate the toxic effects of thallium acetate in C. elegans in early larval stages, considering physiological and behavioral endpoints, as well as the Tl absorption and bioaccumulation.

METHODS

Caenorhabditis elegans (C. elegans) was exposed to Thallium acetate (50, 100, 150, 200, 250, 500, and 1000 μM) in the L1 larval stage, with the purpose to observe the toxic effects invoked until adulthood. Transgenic worms strains were transported GFP, reporters to DAF-16 and were used to verify the antioxidant response. ICP-MS quantified total Tl⁺ concentration to evidence Tl uptake and bioaccumulation.

RESULTS

Thallium acetate caused a significant reduction in the number of living worms (p < 0.0001 in 100-1000 μM), a delay in larval development (p < 0.01; p < 0.001 and p < 0.0001 in 100-1000 μM) through the larval stages, and egg production in the worm's uterus was reduced. Thallium acetate also induced behavioral changes. Additionally, thallium acetate activated antioxidant pathway responses in C. elegans by translocating the DAF-16 transcription factor and activation of SOD-3::GFP expression. The Tl⁺ quantification in worms showed its absorption in the L1 larval stage and bioaccumulation in the body after development.

CONCLUSIONS

Thallium acetate reduced survival, delayed development, caused behavioral changes, induced responses inherent to oxidative stress, and serious damage to the worm's reproduction. In addition, C. elegans absorbed and bioaccumulated Tl⁺. Together, our results highlight the impacts of Tl⁺ exposure in the early stages of life, even for a short period.

The acute systemic toxicity of thallium in rats produces oxidative stress: attenuation by metallothionein and Prussian blue

Thallium (TI) is one of the most toxic heavy metals. Human exposure to Tl occurs through contaminated drinking water and from there to food, a threat to health. Recently, environmental contamination by Tl has been reported in several countries, urging the need for studies to determine the impact of endogenous and exogenous mechanisms preventing thallium toxicity. The cytoprotective effect of metallothionein (MT), a protein with high capacity to chelate metals, at two doses (100 and 600 µg/rat), was tested. Prussian blue (PB) (50 mg/kg) was administered alone or in combination with MT. A dose of Tl (16mg/kg) was injected i.p. to Wistar rats. Antidotes were administered twice daily, starting 24h after Tl injection, for 4 days. Tl concentrations diminished in most organs (p < 0.05) by effect of PB, alone or in combination with MT, whereas MT alone decreased Tl concentrations in testis, spleen, lung and liver. Likewise, brain thallium also diminished (p < 0.05) by effect of PB and MT alone or in combination in most of the regions analyzed (p < 0.05). The greatest diminution of Tl was achieved when the antidotes were combined. Plasma markers of renal damage increased after Tl administration, while PB and MT, either alone or in combination, prevented the raise of those markers. Only MT increased the levels of reduced glutathione (GSH) in the kidney. Finally, increased Nrf2 was observed in liver and kidney, after treatment with MT alone or in combination with PB. Results showed that MT alone or in combination with PB is cytoprotective after thallium exposure.

The Mediating Role of Placental Weight Change in the Association Between Prenatal Exposure to Thallium and Birth Weight: A Prospective Birth Cohort Study

Background: Previous studies have demonstrated the embryotoxicity and fetotoxicity of thallium (Tl). However, the effects of prenatal exposure to Tl on birth weight and placental weight and the mediating role of placental weight in the association of Tl with birth weight remain unclear.

Methods: We recruited 2,748 participants from the ongoing Prenatal Environment and Offspring Health Cohort (PEOH Cohort) study, which was initiated in 2016 in Guangzhou, China. The Tl concentrations in maternal urine samples collected during the first and third trimester were determined by inductively coupled plasma mass spectrometry. Birth weight and placental weight were extracted from maternal medical records.

Results: Pregnant women exposed to the highest tertile of Tl in the first trimester (β = −42.7 g, 95% CI: −82.3, −3.1 g) and third trimester (β = −50.6 g, 95% CI: −99.0, −2.3 g) had babies with lower birth weights than those exposed to the lowest tertile. We also found significant negative associations of exposure to Tl concentrations in the first and third trimester with placental weight. Mediation analyses showed that 50.3% (95% CI: 15.9, 79.2%) and 33.5% (95% CI: 1.3, 80.3%) of the effects of Tl exposure in the first and third trimester on birth weight were mediated by decreased placental weight.

Conclusion: Our results suggest that prenatal exposure to Tl is negatively associated with birth weight and that this association may be mediated by decreased placental weight.

Persistent thallium contamination in river sediments, source apportionment and environmental implications

The adverse impacts of detrimental thallium (Tl) contamination are of increasing concerns to sustainable development. Herein, the contents, distributions and sources of Tl and potential toxic elements (PTEs) (Pb, As, Cr, Cu, Ni, Co, Sb, Cd and U) were investigated in sediments collected in Gaofeng River, which has been contaminated by long-term mining activities, located in Yunfu City, Southern China. Results indicated that excessive Tl levels were found in sediments (1.80-16.70 mg/kg). Sequential extraction procedure indicated that despite a large amount of Tl entrapped in residual fraction, a significant level of Tl (0.28-2.34 mg/kg) still exhibited in geochemically labile fractions, which was easy for Tl mobilization and availability. Pb isotope tracing method further confirmed that the pyrite exploitations may be the prime contaminated contributor (47-76%) to these sediments. These findings highlight that it is essential to establish more effective measures for Tl contamination control and call for engineered remediation countermeasures towards polluted river sediments.