Determination of thallium in biological samples

Evaluation of Monochromatic Excitation X-ray Fluorescence Spectrometry for Rapid Thallium Detection in Biological Samples Using Animal Models

Monochromatic excitation X-ray fluorescence (ME-XRF) spectrometry is a novel technique for trace element analysis, characterized by its simplicity, rapidity, and low cost. The objective of this study was to evaluate the applicability of ME-XRF technique for the measurement of thallium in biological samples. Acute and subacute thallium poisoning experiments were conducted to simulate various scenarios, with blood, urine, and 10 distinct organs collected. Detection was initially performed using ME-XRF technique, followed by validation with inductively coupled plasma mass spectrometry (ICP-MS). Excellent agreement between ME-XRF and ICP-MS values was demonstrated by means of paired sample t-tests and intraclass correlation coefficients. Subsequently, the practical implementation of the proposed technique was demonstrated through an actual case study. In conclusion, this study validates ME-XRF as a suitable alternative to ICP-MS for the measurement of trace heavy metals in biological samples. These efforts promote the development of simpler and faster techniques for heavy metal detection, thereby presenting novel avenues for the prevention and diagnosis of heavy metal poisoning.

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.

Validation of Analytical Method for Determination of Thallium in Rodent Plasma and Tissues by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS)

Thallium (Tl) can be released as a byproduct of smelting, mining, and other industries, causing human exposure. There are knowledge gaps on the toxicity of thallium compounds, so the National Toxicology Program is investigating the toxicity of thallium (I) sulfate in rodents. We developed and validated a method to quantitate Tl in rodent plasma and secondary matrices. Primary matrix standards and validation samples were digested with nitric acid and analyzed for Tl by inductively-coupled plasma - mass spectrometry (ICP-MS). Method performance was validated for linearity, accuracy, precision, and other criteria. Calibration was linear from 1.25 to 500 ng Tl/mL plasma; accuracy (RE) was -5.9 to 2.6% for all calibration standards. The lower limit of quantitation (LLOQ) was 1.25 ng Tl/mL plasma, and the limit of detection was 0.0370 ng Tl/mL plasma. Intra- and interday RE and precision (RSD) were -5.6 to -1.7% and ≤0.8% (intraday) and -4.8 to -1.3% and ≤4.3% (interday), respectively, at three sample concentration levels. Standards up to 10.0 × 10³ ng/mL could be analyzed by dilution with digested blank matrix, with -6.4% RE and 5.4% RSD. Method was also evaluated in post-natal day 4 (PND4) Hsd:Sprague Dawley SD (HSD) dam and pup plasma, gestation day 18 (GD 18) HSD rat fetal homogenate, HSD rat urine, female HSD rat brain homogenate, female B6C3F1 mouse plasma. Background Tl was detected in control fetal and brain homogenates and urine at < 30% of LLOQ response. Results demonstrate that the method is suitable for determination of Tl in rodent matrices for toxicology studies.

Thallium Use, Toxicity, and Detoxification Therapy: An Overview

Thallium (Tl) is released into the environment, where is present at very low levels, from both natural and anthropogenic sources. Tl is considered as one of the most toxic heavy metals; it is a non-essential metal, present in low concentrations in humans. Tl toxicity causes dermatological and gastrointestinal diseases and disorders of the nervous system, and may even result in death. Many isotopes of Tl exist, with different uses. One of the isotopes of this metal (201Tl) is used in cardiovascular scintigraphy and for the diagnosis of malignant tumors such as breast or lung cancer and osteosarcoma bone cancer. Many Tl compounds are tasteless, colorless, and odorless. Due to these characteristics and their high toxicity, they have been used as poisons in suicides and murders for criminal purposes, as well as instances of accidental poisoning. Impaired glutathione metabolism, oxidative stress, and disruption of potassium-regulated homeostasis may play a role in the mechanism of Tl toxicity. Solanum nigrum L. and Callitriche cophocarpa have been suggested as promising agents for the phytoremediation of Tl. In addition, macrocyclic compounds such as crown ethers (18-crown-6) are good candidates to absorb Tl from wastewater. Through this review, we present an update to general information about the uses and toxicity of Tl. Furthermore, the attention is focused on detoxification therapies.

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

Thallium (TI) is one of the most toxic heavy metals and priority pollutant metals. The emerging TI environmental pollution worldwide has posed a great threat to human health. However, based on the World Health Organization (WHO), the risk and severity of adverse health effects of TI in the range of 5-500 μg/L are uncertain. Moreover, evidence regarding the adverse impacts of TI on children's health is still insufficient. Herein, we aim to investigate the early adverse effects of TI on children's health and provide references for the WHO to establish stricter safety limits of TI. From 2015 to 2019, urinary TI and many clinical laboratory parameters related to blood routine, hepatic, renal, myocardial, coagulation function and serum electrolyte were measured in six children aged 1-9 years. The urinary TI concentration ranged from 13.4 μg/L to 60.1 μg/L with a mean of 36.1 μg/L and a median of 34.8 μg/L in six children in 2015. Although only four children felt a little poor appetite, several laboratory abnormalities indicated early damage in liver, renal, and myocardial functions in all children in 2015. After treatment and following up for four years, although the children's TI concentration decreased below 5 μg/L, their liver and renal functions did not completely recover, and their myocardial function worsened. Results indicated that impaired liver, renal, and myocardial functions were closely associated with elevated urinary TI concentration in children. Considering the increasing use of TI in high-technology industries and emerging TI environmental-contamination zones worldwide, establishing stricter safety limits of TI and paying more attention to the adverse health effects of TI on children are urgently required. SUMMARY: We found that a relatively low concentration of thallium (13.4 μg/L to 60.1 μg/L) impaired liver, renal, and myocardial function in six children. After treatment and following up these children for four years, although their urinary TI concentration decreased below 5 μg/L, their liver and renal functions did not completely recover, and their myocardial function worsened.

Thallium toxicity due to audultered infusion with thallium sulfate in eight members belonging to the same family nucleus: Autopsy findings and ICP-MS analysis (inductively coupled plasma mass spectrometry) in a triple homicide

The banning of the heavy metal thallium (Tl) in many Countries, because of its toxicity, led to a remarkable reduction of the number of cases of poisoning both accidental and homicidal forcing us to better study the pharmacokinetics of this poison using new technologies. The Authors, in this work, are reporting the case of a collective thallium toxicosis caused by voluntary adulteration of an infusion with thallium sulfate, occurred in 8 members of the same familial nucleus; the administration of Prussian Blu resulted to be ineffective for 3 of these members that died at a later time. The most peculiar aspects of this rare manner of poisoning are discussed; the analytical procedures used, Inductively Coupled Plasma Mass Spectrometry (ICP-MS) in particular, resulted to be fundamental in the forensic diagnosis process of acute poisoning cause by thallium.

Effect of thallium exposure and its interaction with smoking on lung function decline: A prospective cohort study

BACKGROUND

Thallium (Tl) is a cumulative high toxicant in the environment, but few longitudinal studies have investigated the respiratory impairment of Tl exposure.

OBJECTIVES

This study aimed to evaluate the effect of Tl and its interaction with smoking on lung function decline, and explore the potential mechanisms.

METHODS

The baseline and follow-up lung functions were measured from a prospective cohort study of 1243 workers, who were followed from 2010 to 2014. Their baseline urinary levels of Tl were determined. We also measured the plasma C-reactive protein (CRP) and urinary 8-iso-prostaglandin-F2α (8-iso-PGF2α) in a randomly selected subcohort of 474 subjects.

RESULTS

The results showed that a 2-fold increase in urinary Tl was associated with 29.81 mL (95%CI: 3.83-55.80) increased decline in forced expiratory volume in 1 s (FEV₁). The effect was more pronounced among heavy-smokers (≥15 pack-years) [β(95%CI) = 56.42 mL (9.66-103.19)]. In particular, compared to never-smokers with low Tl, heavy-smokers with high Tl had a separate 158.44 mL (95%CI: 54.88-262.00) and 4.58% (95%CI: 1.40-7.76) increased declines in FEV₁ and percentage of predicted (ppFEV₁), respectively. There was a significant interaction between Tl and smoking intensity on ppFEV₁ decline (P_int = 0.034). More importantly, the increasing level of urinary Tl was correlated with elevated CRP and 8-iso-PGF2α.

CONCLUSION

Our prospective cohort study identified that exposure to high Tl had a deleterious effect on lung function, and this effect may be enhanced by tobacco smoking. Increased inflammation may partly contribute to the joint effects of Tl and smoking on impaired lung function, but the biological mechanisms need further explorations.

Ratiometric Phosphorescent Probe for Thallium in Serum, Water, and Soil Samples Based on Long-Lived, Spectrally Resolved, Mn-Doped ZnSe Quantum Dots and Carbon Dots

Thallium (Tl) is an extremely toxic heavy metal and exists in very low concentrations in the environment, but its sensing is largely underexplored as compared to its neighboring elements in the periodic table (especially mercury and lead). In this work, we developed a ratiometric phosphorescent nanoprobe for thallium detection based on Mn-doped ZnSe quantum dots (QDs) and water-soluble carbon dots (C-dots). Upon excitation with 360 nm, Mn-doped ZnSe QDs and C-dots can emit long-lived and spectrally resolved phosphorescence at 580 and 440 nm, respectively. In the presence of thallium, the phosphorescence emission from Mn-doped ZnSe QDs could be selectively quenched, while that from C-dots retained unchanged. Therefore, a ratiometric phosphorescent probe was thus developed, which can eliminate the potential influence from both background fluorescence and other analyte-independent external environment factors. Several other heavy metal ions caused interferences to thallium detection but could be efficiently masked with EDTA. The proposed method offered a detection limit of 1 μg/L, which is among the most sensitive probes ever reported. Successful application of this method for thallium detection in biological serum as well as in environmental water and soil samples was demonstrated.

The efficient removal of thallium from sintering flue gas desulfurization wastewater in ferrous metallurgy using emulsion liquid membrane

The removal of thallium ions in flue gas desulfurization wastewater from ferrous metallurgic industry was studied by emulsion liquid membrane (ELM) method using 2-ethylhexyl phosphoric acid-2-ethylhexyl ester (P507) as carrier, aviation kerosene (AK) as organic solvent, polyisobutylene succinimide (T154) as surfactant, polyisobutylene (PIB) as additive, and sulfuric acid as internal reagent. Some important influence parameters such as concentrations of carrier, surfactant and stripping agent, agitation speed, extraction time, volume ratios of feed solution to emulsion phase and internal phase to membrane phase, and their effects on the removal efficiency of Tl in the ELM process were investigated and optimized. Under the optimum operating conditions of 2% of carrier, 5% of surfactant, 0.5 M of stripping agent, 350 rpm of agitation speed, 12.5:1 of volume ratio of feed solution to emulsion phase, and 3:1 volume ratio of membrane to internal phase, the maximum extraction efficiency of thallium reached 99.76% within 15-min reaction time. The ICP-MS analysis indicated that the thallium concentration in treated wastewater was below 5 μg/L and could meet the emission standard demand for industrial wastewater enacted by the local government of Hunan province of China. Meanwhile, the extraction of impurity ions calcium and magnesium in the ELM system was investigated. The result showed that an acidic environment would be in favor of the removal of Tl from calcium and magnesium contained in wastewater. Graphical abstract ᅟ.

Presence of thallium in the environment: sources of contaminations, distribution and monitoring methods

Thallium is released into the biosphere from both natural and anthropogenic sources. It is generally present in the environment at low levels; however, human activity has greatly increased its content. Atmospheric emission and deposition from industrial sources have resulted in increased concentrations of thallium in the vicinity of mineral smelters and coal-burning facilities. Increased levels of thallium are found in vegetables, fruit and farm animals. Thallium is toxic even at very low concentrations and tends to accumulate in the environment once it enters the food chain. Thallium and thallium-based compounds exhibit higher water solubility compared to other heavy metals. They are therefore also more mobile (e.g. in soil), generally more bioavailable and tend to bioaccumulate in living organisms. The main aim of this review was to summarize the recent data regarding the actual level of thallium content in environmental niches and to elucidate the most significant sources of thallium in the environment. The review also includes an overview of analytical methods, which are commonly applied for determination of thallium in fly ash originating from industrial combustion of coal, in surface and underground waters, in soils and sediments (including soil derived from different parent materials), in plant and animal tissues as well as in human organisms.

Thallium in spawn, juveniles, and adult common toads (Bufo bufo) living in the vicinity of a zinc-mining complex, Poland

A breeding population of the common toad Bufo bufo living in the vicinity of a Zn-Pb smelting works in Bukowno, Poland was studied for the presence of thallium. Tl concentration was measured in the bottom sediments of the spawning pond, in the laid eggs, in juveniles after metamorphosis, and in the selected tissues of the adult individuals. A very high concentration of Tl was detected in the spawn (13.97 ± 8.90 mg/kg d.w.). In 50% of the spawn samples, levels exceeded 20 mgTl/kg d.w. The issue of maternal transfer of thallium from females to oocytes is discussed. Due to a significant accumulation of thallium, spawn analysis can be used as a sensitive indicator of the presence of this element in the environment and may replace more invasive methods that involve the killing of adult animals. In those regions that are abundant in Zn-Pb ores, the spawn of amphibians may be a very important source of thallium contamination for predators. From among all tissues of the Bukowno adult toads, the livers have shown the highest accumulation of thallium (mean 3.98 mg/kg d.w. and maximum value--18.63). For as many as 96.5% of livers, concentrations exceeded 1.0 mgTl/kg d.w. which is treated as indicative of poisoning.

Human fatality due to thallium poisoning: autopsy, microscopy, and mass spectrometry assays

Thallium has been responsible for many intoxications since its discovery; however, toxicological profiles for thallium in human fatalities have not been updated recently. Autopsy, microscopic investigations, and toxicological analyses were performed on a married couple who died from thallium sulfate intended homicidal poisoning. The distribution of thallium was established by inductively coupled plasma mass spectrometry with hair samples showing the highest thallium concentration. Electron microscopy revealed a dystrophic condition of hair with disorganized cuticle and atrophy of the hair bulb. Thallium interacts with cells at different levels, with prominent ultrastructural injuries in the mitochondria and endoplasmic reticulum, and high concentration of electron dense granules observed in the cytoplasm and mitochondria of several organs. Alopecia, toxic encephalopathy, and peripheral neuropathy were diagnosed in the victims and suggested to be crucial implications for thallium poisoning. The analytical procedures used in this case are of considerable forensic importance in the diagnosis of thallium poisoning.

Ligandless, ion pair-based and ultrasound assisted emulsification solidified floating organic drop microextraction for simultaneous preconcentration of ultra-trace amounts of gold and thallium and determination by GFAAS

In the present work, a new, simple and efficient method for simultaneous preconcentration of ultra-trace amounts of gold and thallium is developed using an ion pair based-ultrasound assisted emulsification-solidified floating organic drop microextraction procedure before graphite furnace atomic absorption spectrometry determination. This methodology was used to preconcentrate the ion pairs formed between AuCl(4)(-) and TlCl(4)(-) and [C(23)H(42)]N(+) in a microliter-range volume of 1-undecanol. Several factors affecting the microextraction efficiency, such as HCl volume, type and volume of extraction solvent, sonication time, sample volume, temperature, ionic strength and [C(23)H(42)]NCl volume were investigated and optimized. Under the optimized conditions, the enrichment factor of 441 and 443 and calibration graphs of 2.2-89 and 22.2-667 ng L(-1) for gold and thallium were obtained, respectively. The intra- and inter-day precision of ± 4.4 and ± 4.9% for Au and ± 4.8 and ± 5.4% for Tl were obtained. The detection limit was 0.66 ng L(-1) for Au and 4.67 ng L(-1) for Tl. The results show that the liquid-liquid pretreatment using ion pair forming, is sensitive, rapid, simple and safe method for the simultaneous preconcentration of gold and thallium. The method was successfully applied for determination of gold and thallium in natural water and hair samples.

Genetic toxicology of thallium: a review

This review summarizes the current knowledge about the general toxicity of thallium (Tl) and its environmental sources, with special emphasis placed on its potential mutagenic, genotoxic, and cytotoxic effects on both eukaryotic and prokaryotic cells. Tl is a nonessential heavy metal that poses environmental and occupational threats as well as therapeutic hazards because of its use in medicine. It is found in two oxidation states, thallous (Tl(+)) and thallic (Tl(3+)), both of which are considered highly toxic to human beings and domestic and wild organisms. Many Tl compounds are colorless, odorless and tasteless, and these characteristics, combined with the high toxicity of TI compounds, have led to their use as poisons. Because of its similarity to potassium ions (K(+)), plants and mammals readily absorb Tl(+) through the skin and digestive and respiratory systems. In mammals, it can cross the placental, hematoencephalic, and gonadal barriers. Inside cells, Tl can accumulate and interfere with the metabolism of potassium and other metal cations, mimicking or inhibiting their action. The effects of Tl on genetic material have not yet been thoroughly explored, and few existing studies have focused exclusively on Tl(+). Both in vivo and in vitro studies indicate that Tl compounds can have a weak mutagenic effect, but no definitive effect on the induction of primary DNA damage or chromosomal damage has been shown. These studies have demonstrated that Tl compounds are highly toxic and lead to changes in cell-cycle progression.

Whole blood thallium determination by GFAAS with high-frequency modulation polarization Zeeman effect background correction

A new technique of blood thallium direct determination based on graphite furnace atomic absorption spectrometry with Zeeman background absorption correction system was designed. The developed technique does not require sample digestion. Sample treatment includes only a fivefold per volume dilution of blood sample with 0.1% (m/v) Triton X-100. L'vov integrated platform was modified with 400 μg of Rh. Matrix modifier (200 μg NH(4)NO(3) and 160 μg Pd(NO(3))(2)) was suggested for coping chloride and blood organic matter interferences. Standard reference material (Clincheck® Plasma Control for trace elements) analysis was used for validation. Additional validation was performed by analyzing spiked blood samples in the whole dynamic range. The dynamic range was 2-50 μg/L. Precision (RSD) was found <12%. Blood thallium limit of detection was 0.2 μg/L.

Thallium toxicity in humans

Thallium is a naturally occurring trace element, widely distributed in the earth's crust, but at very low concentrations. It does not have a known biological use and does not appear to be an essential element for life. It has been considered one of the most toxic heavy metals.Occasionally, there are reports on thallium poisoning as results of suicide or murder attempt or accident. The main threat to humans is through occupational exposure, environmental contamination, and accumulation in food, mainly in vegetables grown on contaminated soil. Increasing use in emerging new technologies and demanding high-tech industry constantly raise concern about exposure risk to all living organisms. Thallium is considered a cumulative poison that can cause adverse health effects and degenerative changes in many organs. The effects are the most severe in the nervous system. The exact mechanism of thallium toxicity still remains unknown, although impaired glutathione metabolism, oxidative stress, and disruption of potassium-regulated homeostasis may play a role. The lack of data about mutagenic, carcinogenic, or teratogenic effects of thallium compounds in humans calls for further research.

Two-year follow-up of two patients after severe thallium intoxication

Information on the prognosis and electrophysiological follow-up of severe thallium poisoning is limited. We report two patients (mother and daughter) who were repeatedly exposed to thallium poisoning experienced hair loss, polyneuropathy, and visual impairment. Nerve conduction studies (NCSs), visual evoked potentials (VEP), brainstem auditory evoked potentials (BAEP) changes, and optical neuropathy developed within a few months latency after the first subjective signs. Normal findings of these electrophysiological methods in the first 2 weeks therefore led in one of our patients to exclusion of thallium as the cause of symptoms. Thallium poisoning was, however, later confirmed by toxicological analysis of blood and/or urine and feces in both the patients and in the microscopic hair analysis of the daughter. Both patients were treated with Prussian blue that increased the elimination of thallium in urine and feces. The hair loss was fully reversible. During a 2-year follow-up after the poisoning, polyneuropathy in the lower extremities improved substantially, but residual impairment in both motor and sensory function, NCSs, VEP, and BAEP remained. Additionally, severe asymmetrical vision impairment persists in both women, with central scotomata and impaired color discrimination in both eyes. Substantial improvement of their visual function is unlikely.

Speciation and determination of thallium by on-line microcolumn separation/preconcentration by flow injection-flame atomic absorption spectrometry using immobilized oxine as sorbent

A flow injection analysis (FIA) system incorporation a microcolumn of immobilized oxine on surfactant-coated alumina had been devised for performing rapid thallium enrichment/matrix removal in flame atomic absorption spectrometry (FAA). The preconcentration is based on the deposition of thallium(I) on microcolumn and subsequent elution with 500 microl of sodium thiosulfate (1 moll(-1)). In the presence of EDTA, only Tl(I) was retained on the microcolumn. Total thallium was determined after reduction of Tl(III) to Tl(I) by hydroxyl amine hydrochloride. A sample volume of 25 ml resulted in a preconcentration factor of 77. Precision at 30 microgl(-1) was 2.6% RSD (n=10). With 25 ml sampling volume a detection limit of 2.5 microgl(-1) was determined. The effect of potential interfering ions on the determination was studied. The method was applied for the determination of thallium in water, waste water, hair, nail, coal, and standard reference alloys. The accuracy was assessed through recovery experiment, independent analysis by Furnace-AAS, and analysis of certified reference alloys.