Thallium concentration

Because of the many different electrolyte solutions employed values are grouped according to the thallium concentration. 

In another cohort study, no statistically significant clinical effects were found, even though urinary concentrations ranging up to 236pg/liter indicated exposures above the threshold limit value (TLV) of O.lmg/m A urine thallium concentration of lOOpg/1 corresponds approximately to a 40 hour/week exposure at O.lmg/m and normal values range between 0.6 and 2.0pg/l. ... 

Cs) and urinary thallium concentrations can guide the recommended duration of therapy. Adjunctive supportive care for possible acute radiation illness (137Cs) or systemic thallium toxicity should be instituted as needed. 

In Stingeder s group the unique capabilities of sector field ICP-MS and LA-ICP-MS were employed to reconstruct details of a homicide by thallium poisoning, which took place about 40 years ago in Austria.29 Thallium was determined in several human bone samples after acid digestion in a microwave oven. The thallium concentration measured by ICP-MS and GF-AAS varied from 1.07-2.63 p,gg 1, which was up to 170 times higher compared to the concentration found in persons who died due of natural causes. LA-ICP-MS was employed to analyze a thumbnail from the poisoned person compared to a control person. Thallium peaks were detected in the nail of the victim at a distance of 2.5 mm from the younger edge of nail.29... 

In one approach crown ethers (31) or (32) are mixed with PVC and a plasticizer such as o-ni-trophenyl octyl ether in THF to give a membrane on evaporation of the solvent. Discs may then be cut and incorporated into electrodes. The resulting electrodes show good selectivity for thallium(I) and are useful in the measurement of thallium concentrations.88... 

The indium concentration was determined by polarographic and colorimetric methods after previous removal of the selenium, and the thallium concentration by a volumetric titration. The attainment of a constant solubility was checked. 

Farver and Nord (84) have found that Tl(II)-2,2 -bripyridyl is formed at a dropping mercury electrode when thallium(III)-2,2 -bipyridyl complexes in 0.1 M KNO3 solution are reduced at low thallium concentrations (<1 mM) and pH >5. They suggested that Tl(II) complexes with other chelating agents (N and O donors) could probably also be observed polarographically. 

However, the obvious line broadening dependence on the total thallium concentration leaves no doubt that this is the dominating reaction path at low Cl/Tl values. Also, here the rate laws are bimolecular, rate = [T1C1 , "][T1C1 "], but the rate constants are several orders of... 

The system Tl-Ta-Se, at low thallium concentrations, gives rise to a phase with the empirical formula Tl TaScj in which x has values between 0.33 and 0.5. A structural study shows the compound to consist of TaSc2 layers between which the thallium atoms are arranged in such a way that both metals attain a trigonal-prismatic co-ordination concerning the selenium atoms. The relevant bond lengths are compared with those of the two structural modifications of TaScj in Table 6. 

Bioavailability of thallium, mainly a monovalent cation, is low. A thallium tolerance has been described (Sensfuss et al. 1986), and this is based on the mutation of a potassium uptake system, though a bacterium faces very unlikely toxic thallium concentrations. 

Normally, ambient air contains < 1 ng T1 per m (Ewers 1988). The range of thallium concentrations in sea water (in the form of n ions) has been reported to be relatively constant at 0.01 to 0.016 pgL , and in non-polluted river water this is 0.01 to 1 pgL (Kaplan and Mattigod 1998). The lowest environmental concentrations were found by Cheam (2001) in arctic snow and ice (< 0.05 to 8.4 ng L ). The high water solubility of thallium compounds may result in the local contamination of river and ground water by mining, smelting, and cement works wastewater (Fbrstner and Wittmann 1979, Cheam 2001). 

Reported values for the normal thallium content of human body fluids and tissues are listed in Table 22.1. These data include only reliable results that were obtained using adequate analytical methods and with sufficient numbers of participants. The data may serve as reference values for unexposed individuals, and may also be used for environmental or toxicological diagnostic purposes. Background thallium concentrations in other human tissues may be classified only as indicative of T1 exposure liver <0.4 to 0.9 pgg dry weight (Johnson 1976), and feces < 0.02... 

Effects on Plants, Animals, and Humans Tab. 22.1 No rmal thallium concentrations in human body fluids and tissue... 

Both T1(I) and T1(III) salts are readily absorbed by the gastrointestinal tract and the skin. Excretion is slow with a half-life of nearly one month. Thallium concentrates in the brain and testes. The lethal dose is less than 1 g of a thallium compound in a single ingestion. Thallotoxicosis involves the nervous system, skin, hair loss, and the cardiovascular system. T1+ can substitute for the similarly sized K+ (Table 2 and Figure 2) and interfere in K+-dependent processes (Figure 2). Recovery from thallotoxicosis takes months and may be incomplete as nervous system damage may be irreversible. Thallium may be the most toxic nonradioactive metal. 

Once the capacity of quantitative FD for alkali and alkaline earth cations was established the investigations were expanded to a wide variety of metals. One focal point in this analytical expansion of the method represents the toxic, heavy metal thallium. This metal exerts a pronounced toxic effect on mammals. Poisonings by thallium ions normally proceed very slowly they are accompanied by loss of hair, severe polyneuritic symptoms and tachycardia, and can culminate in paralysis of the central nervous system. Atomic absorption is a common spectroscopic method for the determination of thallium concentrations down to a few ppm . The direct determination of thallium from human urine reveals a limit of detection of approximately 30 ppb, whereas direct estimation from plasma and brain tissue is not successful without pretreatment. 

Evaluation of the data from FDMS reveals a thallium concentration in the mouse brain of 4.0 + 0.3 mmol/kg fresh weight, which results in 0.8 0.06 /[Pg.36]

In order to determine the distribution of thallium with time in an organism we administered orally 160 mg of thallium per kg body weight to mice. After fixed periods of time the acutely poisoned mice were killed and the thallium concentrations in the heart, liver, kidney and brain were determined by FDMS (Fig. 19). 

Fig. 19. Distribution of thallium with time in the heart O, liver v. Udney , and brain A of mice after administration of 160 mg Tl/kg body wei t. Curves a and b for the brain show the variation in increase of thallium concentrations according to doses of 80 and 130 mg/kg of the toxic heavy...

Various values have been proposed as the upper limit of normal for the quantity of thallium in urine. Most published values for the upper limit of normal thallium concentration in urine are... 

Residents near thallium-emitting cement plants had elevated urine thallium concentrations up to 100-fold higher than unexposed persons [57]. Urinary thallium values for nearby residents actually exceeded those found in workers at the plants. The presumed route of exposure was ingestion of home-grown vegetables. Some of the thallium urine concentrations approached values clinically considered to be toxic (>50p.g/liter) [58] but no definite cases of toxicity were documented [11,57]. An increased incidence of headaches and sleeplessness was noted. An occupational study of 128 workers at these cement plants revealed no evidence of clinical toxicity [12]. Another study of workers manufacturing thallium-based alloys also found no clinical effects [59]. Oil refinery workers who had elevated levels of urine thallium (10-23 p.g/day) were noted to have a mild alopecia areata [60]. A report exists of ill-defined functional changes in the nervous systems of workers exposed to thallium carbonate in the USSR [61]. 

Fig. 10 Distribution of the thallium concentration in bream muscle from Lake Constance and the Bornhdvel Lake district...

Addition of thaliium ions to the deposition solution changed the conductivity of the films as evidenced by a lowering of the necessary deposition potentiai as the thallium concentration was increased. It was thus possible to tailor the electrical characteristics of the film by the selective addition of various ions. 

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