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.

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.

Human biomonitoring to assess exposure to thallium following the contamination of drinking water

In 2014, in some parts of the water distribution system of the municipality of Pietrasanta (Tuscany, Italy), thallium (Tl) levels above the recommended limits were measured and some restrictions to water usage for drinking and food preparation were imposed. The study aimed to assess Tl exposure and possible health effects by means of a human biomonitoring survey. In the 2014–2016 time frame, 2154 urine and 254 hair samples were taken from different population groups and from a control group. The levels of Tl found in urine and hair were statistically higher in exposed groups than in controls and compared to the reference values for the general population. Concentrations in urine were significantly associated with the geographical origin of the sample, the consumption of drinking water and food grown in local gardens. A significant association was found between urine and hair. No positive associations were found between the Tl levels in hair or urine and several self-reported symptoms and health effects, except for sleep disturbance. The study indicates that the concentration of Tl in drinking water can be traced by urine analysis. Urine and hair have proven to be biological matrices that can be effectively used for the evaluation of Tl exposure. To date, the study represents the most extensive human biomonitoring campaign for the evaluation of the Tl exposure available at international level.

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.

Clinical characteristics and treatment of thallium poisoning in patients with delayed admission in China

Thallium is highly toxic and its effects are cumulative. The clinical symptoms of thallium poisoning are non-specific, thereby delaying admission and treatment. This study aimed to summarize the clinical features and treatment experience of patients with delayed admission who experience thallium poisoning.We conducted a retrospective descriptive analysis of patients in our hospital from 2008 to 2018 who had thallium poisoning and experienced a delay in hospital admission. The time from symptom onset to admission was assessed. The patients were divided into 3 groups and descriptive analyses of their clinical characteristics, including basic patient information, symptoms, laboratory test results, examination findings, treatment methods, outcomes, and follow-up information, were conducted.A total of 34 patients with thallium poisoning were included: 8 were admitted to the hospital early or with mild delay, 9 had a moderate delay, and 17 had a severely delayed admission. The time from illness onset to admission was 13 (interquartile range, 7.5-26) days. Some patients with delayed admission had significant symptoms associated with central nervous system damage, and changes in magnetic resonance images and electroencephalograms were also noted. After admission, all patients received Prussian blue treatment, and some patients with relatively high blood concentration received blood purification treatments. Following treatment, the blood and urine thallium concentrations of all patients decreased significantly, and their symptoms were alleviated.Our results show that delayed patient admission in cases of thallium poisoning is associated with greater risk of central nervous system damage. Use of Prussian blue combined with blood purification treatments might improve patients' conditions.

Successful treatment of a patient with severe thallium poisoning in a coma using Prussian blue and plasma exchange: A case report

RATIONALE

This is the first reported severe thallium poisoning patient successfully treated with Prussian blue (PB) and plasma exchange (PE).

PATIENT CONCERNS

A 42-year-old woman in a coma owing to severe thallium poisoning was admitted to our department after day 44 of poisoning. At admission, blood and urine thallium concentrations were 380.0 and 2580.0 ng/mL, respectively.

DIAGNOSIS

The patient was diagnosed with toxic encephalopathy induced by thallium poisoning; in addition, she was also diagnosed with bilateral pneumonia, respiratory failure, moderate anemia, hypoproteinemia, and electrolyte imbalance based on her chest X-ray, blood gas analysis, Hb level, albumin levels, and serum electrolyte results.

INTERVENTIONS

The patient was intubated and treated with PB (6600 mg/d, 15 days in total) combined with PE (once daily, 5 days in total) as well as other symptomatic supportive care measures.

OUTCOMES

After treatments, her blood and urinary thallium concentrations gradually decreased and on the 13th day after admission, the blood thallium concentration decreased to 0 ng/mL. The oxygenation index gradually improved, meantime, the patient gradually regained consciousness, and on the 50th day of admission, the patient's consciousness reverted to a clear-headed state. The patient recovered mostly after 37 months of follow-up.

LESSONS

Through this case, we learned that the gradual reduction in blood and urine thallium concentration and the patient's improved condition is correlated with PB and PE treatment. For patients with severe thallium poisoning, this treatment method might be effective; but the exact curative effect is unconfirmed, requiring further research to verify.

Examining of Thallium in Cigarette Smokers

Smoking is one of the sources of thallium which is considered as a toxic heavy metal. The aim of this study was to determine urinary thallium levels and related variables in smokers, compared to a control group. The study was conducted on 56 participants who had smoked continuously during the year before they were referred to Kashan Smoking Cessation Clinic. Fifty-three nonsmokers who were family members or friends of the smokers were selected as the control group. Urinary thallium was measured in both groups (n = 109) using atomic absorption spectrophotometry. The mean value (with SD) for urinary thallium in the smokers (10.16 ± 1.82 μg/L) was significantly higher than in the control group (2.39 ± 0.63 μg/L). There was a significant relationship between smoking duration and urinary thallium levels (P = 0.003). In a subgroup of smokers who was addicted to opium and opium residues (n = 9), the mean level of thallium (37.5 ± 13.09 μg/L) was significantly higher than in the other smokers (4.93 ± 4.45; P = 0.001). Multiple regression analysis showed opioid abuse, insomnia, and chronic obstructive pulmonary disease (COPD), together were strong predictors of urinary thallium levels in smokers. There was no significant difference in thallium level in hookah smokers (P = 0.299) or in those with COPD compared to other smokers (P = 0.375). Urinary thallium levels of smokers with clinical signs of depression, sleep disorders, memory loss, and sweating were higher than those of smokers without these signs. Since thallium, as other toxic metals is accumulated in the body, and cigarette smoking also involves carcinogenic exposures and health hazards for passively exposed people, the need for cigarette control policies is emphasized.

Metals in Urine and Diabetes in U.S. Adults

Our objective was to evaluate the relationship of urine metals including barium, cadmium, cobalt, cesium, molybdenum, lead, antimony, thallium, tungsten, and uranium with diabetes prevalence. Data were from a cross-sectional study of 9,447 participants of the 1999-2010 National Health and Nutrition Examination Survey, a representative sample of the U.S. civilian noninstitutionalized population. Metals were measured in a spot urine sample, and diabetes status was determined based on a previous diagnosis or an A1C ≥6.5% (48 mmol/mol). After multivariable adjustment, the odds ratios of diabetes associated with the highest quartile of metal, compared with the lowest quartile, were 0.86 (95% CI 0.66-1.12) for barium (Ptrend = 0.13), 0.74 (0.51-1.09) for cadmium (Ptrend = 0.35), 1.21 (0.85-1.72) for cobalt (Ptrend = 0.59), 1.31 (0.90-1.91) for cesium (Ptrend = 0.29), 1.76 (1.24-2.50) for molybdenum (Ptrend = 0.01), 0.79 (0.56-1.13) for lead (Ptrend = 0.10), 1.72 (1.27-2.33) for antimony (Ptrend < 0.01), 0.76 (0.51-1.13) for thallium (Ptrend = 0.13), 2.18 (1.51-3.15) for tungsten (Ptrend < 0.01), and 1.46 (1.09-1.96) for uranium (Ptrend = 0.02). Higher quartiles of barium, molybdenum, and antimony were associated with greater HOMA of insulin resistance after adjustment. Molybdenum, antimony, tungsten, and uranium were positively associated with diabetes, even at the relatively low levels seen in the U.S.

POPULATION

Prospective studies should further evaluate metals as risk factors for diabetes.

Determination of thallium at ultra-trace levels in water and biological samples using solid phase spectrophotometry

A new simple, very sensitive, selective and accurate procedure for the determination of trace amounts of thallium(III) by solid-phase spectrophotometry (SPS) has been developed. The procedure is based on fixation of Tl(III) as quinalizarin ion associate on a styrene-divinylbenzene anion-exchange resin. The absorbance of resin sorbed Tl(III) ion associate is measured directly at 636 and 830 nm. Thallium(I) was determined by difference measurements after oxidation of Tl(I) to Tl(III) with bromine. Calibration is linear over the range 0.5-12.0 μg L(-1) of Tl(III) with relative standard deviation (RSD) of 1.40% (n=10). The detection and quantification limits are 150 and 495 ng L(-1) using 0.6 g of the exchanger. The molar absorptivity and Sandell sensitivity are also calculated and found to be 1.31×10(7) L mol(-1)cm(-1) and 0.00156 ng cm(-2), respectively. The proposed procedure has been successfully applied to determine thallium in water, urine and serum samples.

Toxicological status of children with autism vs. neurotypical children and the association with autism severity

This study investigates both the level of toxic metals in children with autism and the possible association of those toxic metals with autism severity. This study involved 55 children with autism ages 5-16 years compared to 44 controls with similar age and gender. The study included measurements of toxic metals in whole blood, red blood cells (RBC), and urine. The autism group had higher levels of lead in RBC (+41 %, p = 0.002) and higher urinary levels of lead (+74 %, p = 0.02), thallium (+77 %, p = 0.0001), tin (+115 %, p = 0.01), and tungsten (+44 %, p = 0.00005). However, the autism group had slightly lower levels of cadmium in whole blood (-19 %, p = 0.003). A stepwise, multiple linear regression analysis found a strong association of levels of toxic metals with variation in the degree of severity of autism for all the severity scales (adjusted R(2) of 0.38-0.47, p < 0.0003). Cadmium (whole blood) and mercury (whole blood and RBC) were the most consistently significant variables. Overall, children with autism have higher average levels of several toxic metals, and levels of several toxic metals are strongly associated with variations in the severity of autism for all three of the autism severity scales investigated.

Thallium pollution in China: A geo-environmental perspective

It is well known that thallium (Tl) is a non-essential and toxic metal to human health, but less is known about the geo-environmentally-induced Tl pollution and its associated health impacts. High concentrations of Tl that are primarily associated with the epithermal metallogenesis of sulfide minerals have the potential of producing Tl pollution in the environment, which has been recognized as an emerging pollutant in China. This paper aims to review the research progress in China on Tl pollution in terms of the source, mobility, transportation pathway, and health exposure of Tl and to address the environmental concerns on Tl pollution in a geo-environmental perspective. Tl associated with the epithermal metallogenesis of sulfide minerals has been documented to disperse readily and accumulate through the geo-environmental processes of soil enrichment, water transportation and food crop growth beyond a mineralized zone. The enrichments of Tl in local soil, water, and crops may result in Tl pollution and consequent adverse health effects, e.g. chronic Tl poisoning. Investigation of the baseline Tl in the geo-environment, proper land use and health-related environmental planning and regulation are critical to prevent the Tl pollution. Examination of the human urinary Tl concentration is a quick approach to identify exposure of Tl pollution to humans. The experiences of Tl pollution in China can provide important lessons for many other regions in the world with similar geo-environmental contexts because of the high mobility and toxicity of Tl.

[Thallium content in adults older than 45 ages at Hezhang County of Guizhou Province]

OBJECTIVE

To investigate the feature of Thallium content in adults of heavy metal contaminated district due to mining of Hezhang County, Guizhou Province. METHODS The subjects older than 45 ages were randomly recruited from the mineralized district (Magu village) and no-mineralized district (Salaxi viillage) , urine of villagers were collected and thallium content in urine were detected with ICP-MS.

RESULTS

The average thallium contents in urine of Magu villagers were higner than those of Salaxi villagers,The urinary thallium contents of female were higner than those of male. The urinary thallium contents of residents in two districts were mostly under the upper limit of exposure in human bodies.

CONCLUSION

There was no villager suffered from chronic poisoning of thallium in the two observing districts, the 95% upper limits of urinary thallium content for nonoccupational women older than 45 ages in Magu village was 8 microg/gCr and those for other nonoccupational subjects older than 45 ages was 5 microg/gCr.

[Measurement of thallium content in human urine by atomic absorption spectrometry after acute poisoning]

The problem of poisoning with thallium-containing substances continues to be of current concern. According to the Bureau of Forensic Medical Examination, Moscow, specimens of biological materials from more than 20 victims of such poisoning were delivered for analysis in 2006. The total number of thallium poisoning episodes during the period since 1996 exceeded 50. Materials for thallium determination in biological fluids (human blood and urine) using flame atomic absorption spectrometry were prepared by dry mineralization of accurately weighed samples; acidic solutions of the products of mineralization were used for analysis. Due to peculiar kinetic features of thallium ion absorption in the gastro-intestinal tract, blood could not be used as a biological marker of poisoning. The level of thallium in urine samples was found to vary from 1.00 to 4,600 mcg/l (with the estimation of confidence intervals in each case). Results of chemical analysis correlated with pathological symptoms derived from the patients' discharge summaries and literature reports on dose-effect relationships. Based on these findings, practically all the examined cases were characterized as severe acute poisoning.

Development of a selective and sensitive spectrophotometric method for the trace determination of thallium(III) using 3-methyl-2-benzothiazolinone hydrazone hydrochloride and N-(1-naphthyl)-ethylenediamine dihydrochloride

A simple, selective, sensitive, and rapid spectrophotometric method has been developed for the determination of thallium(III) using 3-methyl-2-benzothiazolinone hydrazone hydrochloride and N-(1-naphthyl)-ethylenediamine dihydrochloride. The obtained product had an absorption maximum of 590 nm. Beer's law was valid over the concentration range of 0.15-8 microg/mL. The molar absorptivity and Sandell's sensitivity of the colored system were 2.93 x 10(4) L/mol x cm and 0.00723 microg/mL, respectively. The effect of different acids on the sensitivity of the method, interference by foreign substances, the optimum reaction conditions, and other analytical parameters were evaluated. The proposed method has been successfully applied in the analysis of T1(III) in standard reference materials, synthetic mixtures, and water and urine samples. The performance of the proposed method was evaluated in terms of Student's t-test and variance ratio F-test, which indicated the significance of the proposed method over reported methods.

Short-term thallium intoxication: dermatological findings correlated with thallium concentration

BACKGROUND

The dermatological features and skin biopsy findings of short-term thallium intoxication have been described. However, the correlation between the dermatological findings and the thallium concentration, the prognosis of peripheral neuropathy, and a cutaneous nerve biopsy study are lacking.

OBSERVATIONS

Two patients initially developed perioral numbness, erythematous facial rashes, and polyneuropathy after ingesting thallium-containing water. Severe diffuse alopecia was noted, and a skin biopsy specimen revealed parakeratosis and vacuolar degeneration of the basal layer. Examinations of the hair mount demonstrated a tapered appearance of the anagen root. A serial cutaneous nerve biopsy study showed a loss of epidermal nerves 7 weeks and even 1 year after the thallium intoxication. A toxicology survey disclosed a high concentration of thallium (about 3124 mg/L) in the water. The clinical dermatological features subsided completely, but polyneuropathy with severe painful feet persisted. The blood and daily urinary thallium concentrations decreased slowly in the following 3-month period.

CONCLUSIONS

The clinical dermatological features subsided completely, but painful polyneuropathy persisted. The series cutaneous nerve biopsy specimens showed persistent damage to the sensory nerve endings. The disappearance of the dermatological features and the appearance of Mees lines correlated with the decrease of blood and urinary thallium concentrations.

Central nervous system effects in acute thallium poisoning

We report the central nervous system manifestations, neuropsychological studies and brain magnetic resonance image (MRI) findings of two patients with acute thallium intoxication. Neurologically the patients suffered from confusion, disorientation, and hallucination in the acute stage, followed by anxiety, depression, lack of attention, and memory impairment, in addition to peripheral neuropathy. Neuropsychological tests revealed an impairment of memory function, including reversed digital span, memory registration, memory recall, memory recognition, similarity, proverb reasoning, and verbal fluency. High concentrations of thallium were found in the urine, blood, and drinking water of these two patients. Brain MRI showed lesions in the corpus striatum in one patient. During the follow-up periods, the clinical manifestations and neuropsychological studies showed a slowly progressive improvement, and a follow-up brain MRI 1.5 months later demonstrated a resolution of the lesions. We conclude that thallium intoxication might induce encephalopathy, and brain MRI studies demonstrated the acute-stage brain lesions in a severe intoxicated patient. In addition, neuropsychological tests also confirmed memory deficits, although the brain lesions in the corpus striatum might resolve.

[Nervous system involvement in three children poisoned with thallium]

Three children, aged 5, 10 and 16 years, poisoned with thallium were hospitalized. Two of them suffered from sensory-motor and third from sensory polyneuropathy and additionally in the youngest child severe encephalopathy was observed. The correlations between serum and urine thallium levels and the severity of the symptoms in the course of the disease were positive. The most severe symptoms and the highest thallium level were observed in the youngest child.

[A case of family thallium poisoning from unidentified source]

The authors described a case of thallium poisoning with thorough analysis and further treatment including novelty methods of hemofiltration and hemodialysis.

A simple and rapid spectrophotometric determination of thallium(III) with trifluoperazine hydrochloride

A simple, sensitive and rapid spectrophotometric method was developed for the determination of thallium(III) using trifluoperazine hydrochloride (TFPH). The method is based on the oxidation of TFPH by thallium(III) in a phosphoric acid medium to form a red-colored radical cation with an absorption maximum at 505 nm. Beer's law is valid over the concentration range of 0.5 - 6.5 microg ml(-1) of thallium(III). The molar absorptivity and Sandell's sensitivity of the color system are 2.14 x 10(4) l mol(-1) cm(-1) and 0.0095 microg cm(-2), respectively. The optimum reaction conditions and other analytical parameters were evaluated. The tolerance limit of the method towards various ions usually associated with thallium has been studied. The proposed method has been successfully applied to the analysis of thallium in alloys, minerals, standard reference material, water, and urine samples.

Thallium poisoning in Israel

We report the first case of thallium poisoning in Israel in almost 30 years. A 40-year-old man was apparently poisoned by a business associate when, on several occasions, he unknowingly drank an alcoholic beverage containing the toxic substance. Delayed admission and recurrent thallium ingestion resulted in both acute and chronic symptoms being present concomitantly. Conventional treatment modalities (Prussian blue and forced diuresis) were employed. The patient survived, although neurological sequelae ensued. The problems encountered in diagnosis and treatment of this relatively uncommon entity are discussed.

The determination of metals (antimony, bismuth, lead, cadmium, mercury, palladium, platinum, tellurium, thallium, tin and tungsten) in urine samples by inductively coupled plasma-mass spectrometry

OBJECTIVE

An analytical method has been established to determine the concentration of antimony (Sb), bismuth (Bi), lead (Pb), cadmium (Cd), mercury (Hg), Palladium (Pd), platinum (Pt), tellurium (Te), tin (Sn), thallium (Tl) and tungsten (W) in urine. The aim was to develop a method which is equally suitable for the determination of environmentally as well as occupationally caused metal excretion.

METHODS

Inductively coupled plasma-mass spectroscopy (ICP-MS) was used for the determination of metals. Calibration was done using aqueous solutions and standard addition respectively.

RESULTS

Urine samples of 14 persons occupationally non-exposed to metals were analysed. With the exception of Pt and Bi all the metals were found in these urine samples. The detection limits for these metals lie between 5 and 50 ng/l.

CONCLUSIONS

For some metals, which are important from an occupational as well as an environmental viewpoint, ICP-MS is more sensitive than atomic absorption spectrometry (AAS). ICP-MS, moreover, is welcome as a reference method for AAS with the additional advantage of multi-element measurement.

Treatment of severe thallium intoxication

CASE REPORT

We report a successfully treated case of severe thallium intoxication. In spite of very high serum thallium (5,240 micrograms/L), symptomatology was minor and recovery complete. Prussian Blue was administered, diuresis was enhanced by intravenous fluids and a prolonged hemodialysis was started early. High blood flows (300 mL/min) and intravenous potassium chloride supplements, to mobilize thallium from the tissues, resulted in good clearances (96 to 150 mL/min). In order to prevent the well known complications, we recommend aggressive treatment of severe thallium intoxication.

[Methods of diagnosis of thallium intoxication and its antidote therapy]

Absence of early signs specific for thallium intoxication requires objective diagnostic methods. The studies covered 4 techniques: electroretinography (ERG), assessment of urine levels of thallium and delta-aminolevulinic acid, capillaroscopy. The authors supported their previous foundation concerning diagnostic value of ERG for early diagnosis of thallium effects (higher amplitude of b-wave in one and that of a-wave in 8 out of 10 examinees). Further experimental and clinical basis for grading the intoxication through amounts of urinary thallium were found promising. Capillaroscopy method appeared informative: 8 out of 12 examinees demonstrated spastic and atonic state of hand capillaries--that provided objective verification of vascular disorders in workers exposed to thallium and its derivatives.

[Repeated ingestion with suicidal intent of potentially lethal amounts of thallium]

30 minutes after drinking half a cup of rat poison a 16-year-old girl was admitted to hospital. In addition to various enteric detoxification measures forced dialysis was instituted and, after the urinary thallium level had become known (9 mg/l), haemodialysis was begun and ferric ferrocyanide (Prussian blue) administered (0.5 mg daily for six days). She had no symptoms at any time. After 10 days she was discharged. Five days after discharge she was again admitted, with colic-like abdominal pain, vomiting, paraesthesias of the hands and feet, and in a state of agitation. She had once again ingested rat poison, about one cup. Physical examination revealed little of consequence, except diffuse alopecia. Urinary thallium concentration was 37 mg/l. In the electrocardiogram the P-R interval was shortened to 0.11 s and T waves inverted in leads III and V1. Electronmicroscopy of cardiac and skeletal biopsies revealed lipid droplets, increased sarcoplasm and widening of some of the tubules. Treatment consisted of haemodialysis, forced diuresis (1 l urine/h), administration of ferric ferrocyanide, orthograde intestinal infusions and potassium substitution (serum level: 5 mmol/l). After 28 days the patient was discharged into psychiatric care.

Trace element reference values in tissues from inhabitants of the European Union. VIII. Thallium in the Italian population

In order to establish reference values of thallium in tissues of the general population the element was determined in blood (TlB) and urine (TlU) of 123 healthy inhabitants living in the Marche region, Central Italy. The analysis was carried out by inductively coupled plasma-mass spectrometry (ICP-MS; detection limit in our experimental conditions, 0.001 micrograms Tl/I), which was validated by neutron activation analysis (NAA) and laser induced fluorecence (LIF) spectroscopy. The check of pre-analytical factors indicated a low risk of contamination and loss of Tl during sampling, handling and storage before the instrumental analysis (blank of the entire procedure less than the detection limit). Mean values of TlU and TlB were 0.066 micrograms Tl/l and 0.063 micrograms Tl/l, respectively (median in both cases 0.057 microgram Tl/l). No conclusive evidence concerning the distribution followed by our data set, normal or log-normal, were drawn, although Lilliefors test and Kolmogorov's D-test showed a tendency for TlB to follow both the normal and the log-normal while TlU followed a log-normal distribution. Overall correlations between TlU and TlB are rather weak. A significant, but not high, correlation (P < 0.0004, r = 0.44) was observed in females. Age, sex, smoking habits and alcohol consumption did not seem to play any role on TlU and TlB. Tentatively proposed reference intervals are 0.019-0.17 microgram Tl/l (urine) and 0.014-0.19 microgram Tl/l (blood).

Acute thallium toxicosis in a dog

A Doberman Pinscher was evaluated for acute onset of gastroenteritis, characterized by anorexia, hematemesis, and hematochezia. The dog had ingested mole bait containing thallium 2 days prior to admission. Thallium toxicosis was confirmed by detection of thallium in the urine, using colorimetric analysis. The dog responded well to administration of antibiotics, fluids administered IV, warm-water enemas, and oral administration of activated charcoal slurries.

Effectiveness of palladium matrix modification for the determination of thallium by graphite furnace atomic absorption spectrometry

The effect of palladium matrix modification on the determination of thallium has been investigated. The effect of palladium combined either with ammonium nitrate or with magnesium nitrate on the sodium chloride interference was systematically studied and was compared with that of the classical sulfuric acid modifier. A combination of 6 micrograms palladium with 100 micrograms ammonium nitrate allows the direct determination of thallium in ten-fold diluted blood against matrix-free standards. The detection limit (3 sigma) in the undiluted blood was calculated to be 25 micrograms.1(-1). For the urine analysis the standard addition technique is recommended because a complete thallium recovery for all different urine samples studied was not always obtained.

Biochemical diagnosis of an hereditary aminolaevulinate dehydratase deficiency in a 63-year-old man

Porphyrin metabolism was investigated in a 63-year-old male patient who developed a subacute onset polyneuropathy with predominance of motor signs in the upper limb. The screening for lead, cadmium, mercury, aluminum and thallium was negative. The study of porphyrin metabolism showed remarkable abnormalities, particularly a very high level of plasmatic 5-aminolaevulinic acid contrasting with a normal level of porphobilinogen and a nearly complete loss of activity of aminolaevulinic acid dehydratase with no regenerative response to dithiothreitol or zinc ions. The other causes of aminolaevulinic acid dehydratase deficiency (tyrosinaemia, alcoholism, smoking, cirrhosis, renal insufficiency, diabetes mellitus) were ruled out. The diagnosis of primary aminolaevulinic acid dehydratase deficiency was proposed and confirmed by the familial study, which revealed the existence of several heterozygous members in this family.

[Thallium-induced alopecia]

A case of accidental Thallium intoxication showing, as the only sign, alopecia of the scalp with depigmentation of the hair, is described. A 21 year old woman developed acute loss of hair after ingestion of contaminate tomatoes. No further signs of intoxication were evident. The diagnosis has been made by evidencing Thallium in the urine (colorimetric method) and in the hair (atomic absorption spectrophotometry). Moreover, the clinical and histopathological findings of Thallium alopecia are described.

Environmental exposure to thallium

This paper reviews recent data and findings concerning the sources of thallium in the environment and its current environmental levels and exposures, particularly with respect to human exposure. Special emphasis is given to some recent cases of environmental thallium pollution that were recognized around several cement factories in the Federal Republic of Germany. Contaminated food grown in these areas gave rise to a significantly increased thallium exposure of the population living there. Recent studies show that the thallium level in human urine normally is below 1 micrograms/g creatinine and that the normal concentration range of thallium in human air is approximately 5-10 ng/g. These data allow to recognize even minor undue exposure to thallium in the work and general environment.

Interlaboratory survey of the quality of urinary arsenic and thallium assays in the European community

The present investigations were performed to assess the feasibility of an international round robin on biological samples, to assess the overall performance of toxicological laboratories in the European Community (EC) and the applicability of analytical methods used. Twelve laboratories representing 10 member countries within the Community, which could be considered to be well qualified for this type of work, participated in this study. The set-up chosen was that of a so-called long-term interlaboratory survey. It appeared that quality assurance by an international round robin is feasible within the EC. The samples consisted of arsenic and thallium, both at a high and a low level and the results of the individual laboratories as well as interlaboratory data are reported. In general, a good overall performance was seen, and the methods used showed acceptable accuracy and precision.

Determination of thallium in urine with Zeeman effect graphite furnace atomic absorption

Thallium is determined in urine with a simple dilution as the only sample pretreatment. Zeeman effect background correction provides adequate accommodation for non-atomic absorption such that sufficient diluted urine can be introduced into the furnace to achieve a detection limit of 0.5 ng/mL. Precision and accuracy were evaluated with Environmental Protection Agency water samples and in vitro spiked urine pools; precision of 15% at the 6 ng/mL level was observed. Diluted urine was used in calibration, with only 4 to 5% difference in slope observed within run among randomly selected urine specimens.

Thallium poisoning--a case report

An accidental outbreak of thallium poisoning in the Geological Survey of India, Calcutta, is investigated with a detailed follow-up of one case. Aetiopathogenesis is briefly mentioned.

Thallium intoxication in a dog

A fatal case of thallium poisoning was described in a dog. Clinical signs included vomiting, gastroenteritis, and dermal lesions. Chemical analysis of urine, liver, and kidney from the dog revealed 98, 7, and 34 ppm thallium, respectively, on a wet-weight basis.

Interlaboratory survey on thallium in urine

Quality assurance of analytic results was legalized in the Federal Republic of Germany by the law regulating the calibration of measuring devices of July 11, 1969, and the ordinance concerning the exception from compulsory calibration dated June 29, 1970. Accordingly, in the field of health care the Guidelines of the Medical Society of West Germany for the realization of quality assurance activities have to be followed. Since January 1, 1974, the law regulating the calibration of measuring devices has been fully effective. In the field of legal medicine the clinico-toxicologic analysis is considered to be a part of health care. As far as quantitative determinations are considered, these analyses have to follow the regulations mentioned above. To fulfil the basic program, adequate control samples are necessary. For toxicologic analysis there have been no control samples so far. Therefore, a control sample for thallium has been developed which can be used for long- and short-term interlaboratory surveys. The results are reported.

[Structure of the hair in thallium poisoning]

The alterations in the hair roots discovered by Widy in 1956 were interpreted as accumulations of pigment which form as a consequence of a catalytic action of the poison. The goal of the present investigation was to clarify the structure of these inclusions. Hair from the heads of six victims who were involved in the poisoning of Würzburg medical students in January 1983 was available as investigation material. In the investigation in transmitted light and in polarized light, the black zones typical for thallium intoxication were found filling to varying extents the root and hair shaft near the root. Their intensity corresponded to the degree of severity of the intoxication. When examined under reflected light, the inclusions were shown up with a white color. They thus showed the same optical behavior as the air-filled medullary strand of normal hairs. This indicates that gaseous constituents are involved. This hypothesis could be confirmed by further investigations. After mechanical damage to the hair (pressing under high pressure), the gaseous inclusions disappeared and with them the "thallium strip." The same effect was attained by the chemical action of various acids, embedding agents, and dye solutions. This process was especially rapid after exposure to thioglycolic acid; the escape of the gas bubbles can be directly observed here. Scanning electron microscopic investigations on transverse sections of hair revealed a loosening of the spindle-shaped elements of the fiber layer as signs of structural disturbance. The gaseous constituents in thallium hair arise as the result of a trophic disorder in keratin formation. The structural alteration due to this leads to alopecia.

Intestinal absorption and excretion of thallium (201Tl) in the rat

The gastrointestinal transport of 201Tl-labelled monovalent thallium has been studied in normal and rats with cannulated bile ducts using an in vivo ligated loop technique. A marked difference in the Tl absorptive capacity among the various sections of the gut was observed. 201Tl was taken up more quickly from the colon than from any other segment and the uptake from the ileum and jejunum was higher than from the stomach. In addition, considerable amounts of the intravenously administered thallium were excreted into the intestinal lumen. The biliary excretion was very low compared with the direct transfer of 201Tl across the gastrointestinal wall that occurred against a tissue-to-plasma concentration gradient. In the rat, the large intestine seems to be the major area for the enteral reabsorption and recycling of thallium (I) ions.

[Nature of the black zones in hair following ingestion of thallium]

A total of 510 hairs with Widy's zones from 6 cases of poisoning were microscopically studied, both with light from above and from below. In every instance when the light came from below the zones appeared lighter in colour when pressure was applied. This lighting-up in color was reversible. This effect is incompatible with the opinion, still prevalent today, that the zones may be explained by hyperpigmentation. Quite frequently the zones became lighter during a prolonged exposure to water while simultaneously gas bubbles developed. However, even after extensive exposure to thioglycolic acid the zones did not disappear entirely in all cases. We explain these phenomena with the total reflection of the light at numerous bordering surface of substances with differing indices of fraction. We measured the thallium concentration in the urine and in the hair during the time interval between two thallium poisonings with the result that in those parts of the hair which had grown during a period when no thallium level was measured in the urine we found discernibly to strongly increased thallium concentrations. The results of our study indicate that, considering the most recent knowledge, proof of multiple thallium poisoning ought not to be attempted by means of fractional chemical investigation of the hair alone.

A comparison of two methods for the determination of thallium in urine. Differential pulse anodic stripping voltammetry and flameless atomic absorption spectrophotometry

Two analytical procedures for the determination of thallium in urine are evaluated and compared. The two methods consist of differential pulse anodic stripping voltammetry and flameless atomic absorption spectrophotometry. Both procedures correlated well and were found to be acceptable in terms of precision and analytical recovery. However, a solvent extraction step proved to be necessary for the AAS procedure, and the linearity with respect to the concentration range was rather limited. The method based on DPASV is simple, accurate, precise, and sensitive and does not require any pretreatment of the sample. We therefore recommend the voltammetric procedure for the determination of thallium in urine, as described in this paper.

Repeated surveillance of exposure to thallium in a population living in the vicinity of a cement plant emitting dust containing thallium

From 1979 to 1981, several medical surveys were carried out among a population living in the vicinity of a cement plant that emitted dust containing thallium until August, 1979. Air, soil, plants, and domestic animals in the area were contaminated by thallium and this led to an increased intake of thallium in the population, mainly due to the consumption of home-grown vegetables and fruit. In order to assess the degree of the individuals' exposure to thallium, thallium levels in 24-h urine samples (TlU) were determined. Three surveys were carried out from September to December, 1979 to assess the degree of thallium exposure of different parts of the general population. Subjects with relatively high exposure, as indicated by the results of the above mentioned population surveys, or those suffering from health disorders that might be related to an increased intake of thallium, were reexamined several times from 1979-1981. Special attention was also given to children attending a kindergarten situated about 0.5 km from the cement plant. As compared to an "unexposed" reference population (mean TlU: 0.3 microgram/l), the majority of the population living in the cement plant area had significantly elevated urinary thallium levels (range: less than 0.1-76.5 micrograms/l) indicating a substantially increased environmental exposure. A reduction of the intake of thallium was mainly achieved by the fact that the population, as advised by the authorities, largely avoided the consumption of home-grown, potentially contaminated foodstuffs. Reports on the teratogenicity of thallium in certain animal species caused great concern that thallium might have exerted teratogenic effects on the newborn of women exposed to thallium during pregnancy. Therefore, an investigation of children born between January, 1978 and August, 1979 (n = 297) was carried out. Although the number of congenital malformations was greater than expected, we conclude, considering carefully all data available, that there is likely no causal relationship between thallium and the occurrence of congenital malformations in the children investigated.