Thallium compounds toxicity

Intermetallic compounds with gallium are used as semiconductors. Indium is used to coat other metals to protect against corrosion, especially in engine bearings it is also a constituent of low-metal alloys used in safety sprinklers. The toxicity of thallium compounds has limited the use of the metal, but it does find use as a constituent of high-endurance alloys for bearings. 

The relative toxicities of thallium compounds depend on their solubHities and valence states. Soluble univalent thallium compounds, eg, thaHous sulfate, acetate, and carbonate, are especiaHy toxic. They are rapidly and completely absorbed from the gastrointestinal tract, skin peritoneal cavity, and sites of subcutaneous and intramuscular injection. Tb allium is also rapidly absorbed from the mucous membranes of the respiratory tract, mouth, and lungs foHowing inhalation of soluble thallium salts. Insoluble compounds, eg, thaHous sulfide and iodide, are poorly absorbed by any route and are less toxic. 

Eor laboratory use, cyclopentadienylthalLium [34822-90-7] reacts cleanly with TiX compounds, where X is halogens (258—264). The cost and toxicity of thallium compounds ate drawbacks to large-scale use. However, Cp2Pb may, in certain cases, be useful (see Lead compounds Thallium and thallium compounds) (265). 

This reaction avoids the use of toxic thallium compounds. 

A variant of the Williamson ether synthesis uses thallium alkoxides. The higher reactivity of these can be of advantage in the synthesis of ethers from diols, triols and hydroxy carboxylic acids, as well as from secondary and tertiary alcohols on the other hand however thallium compounds are highly toxic. 

Caution Thallium compounds are highly toxic.3 However, they may he safely handled if prudent laboratory procedures are practiced. Rubber gloves and laboratory coats should be worn and reactions should be carried out in an efficient hood. In addition, thallium wastes should be collected and disposed of separately (Note 1). 

CAUTTON Thallium salts are very toxic when inhaled, ingested, or absorbed through the skin. Appropriate safety precautions and procedures should be taken when handling and disposing of thallium compounds. 

Effect of Thallium on Plants and Animals. On January 29, 1863, R. C. Bottger announced that he had detected spectroscopic traces of thallium in wine, chicory, tobacco, sugar beet, and beech wood, and had concluded that it must be widely diffused in the vegetable kingdom (47, 73). Because of the toxicity of thallium compounds, they are sometimes added in small concentrations to the soil of rodent-infested fields. Too high a concentration of thallium inhibits germination, growth rate, and chlorophyll formation in the crops, especially in rainy weather (78). 

Caution. Compounds of thallium are toxic. This procedure should be carried out in a well-ventilated hood protective gloves should be worn to avoid any contact with thallium compounds. Residues containing thallium compounds must be disposed of in accordance to toxic waste disposal procedures. 

Caution. Thallium compounds are extremely toxic. Avoid inhalation and contact with skin. Carry out this procedure in a well-ventilated hood and use neoprene gloves. Residues containing thallium compounds must carefully be disposed in accordance with its toxic nature. 

Thallium and thallium compounds are toxic and skin contact must be avoided, Impervious gloves and aprons should be worn and excellent ventilation and masks should be provided where dusts and fumes may be present,... 

Of course, what the students are really interested in is why thallium is poisonous. Surprisingly, thallium is toxic because it mimics potassium in the body. But why would thallium behave like potassium As we study the periodic table and chemical periodicity, there is no immediate reason to suspect that these two elements would have similar properties. A close look at the electron shell arrangement of thallium and potassium, however, reveals that both form +1 ions. Since Tl+ ions also happen to be similar in size to K+ ions, they are able to replace potassium ions in cellular processes. (Thallium poisoning is treated with a compound called Prussian blue, which binds to +1 ions and thus facilitates their removal from the body.) It is clear then that we cannot understand the toxicity of thallium without studying its atomic structure and electron distribution. But chemistry is only part of the story. The effects of thallium poisoning only make sense if the... 

Caution. Metal carbonyls and thallium compounds, especially the volatile 1,3-diketonates, are toxic. All experiments with these chemicals should be conducted carefully in a well-ventilated fume hood. 

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. ThaUinm 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. 

As this summary indicates, thallium compounds are dangerously and cumulatively toxic even at low levels. They should be handled with great care and respect, never being allowed to touch the skin or be ingested. 

Thallium has two important oxidation states, Tl (-El) and Tl (+3). The trivalent form more closely resembles aluminum and the monovalent form more resembles alkali metals such as potassium. The toxic nature of the monovalent Tl is due to its similarity to potassium in ionic radius and electrical charge. Thallium sulfate use as a pesticide was restricted in 1965 in the USA and the World Health Organization (WHO) recommended in 1973 against its use as a rodenticide due to its toxicity (WHO, 1973). From 1912 to 1930, thallium compounds were used extensively for medicinal purposes for example in the treatment of ringworm (because of the depilatory effects), dysentery, and... 

OSHA PEL TWA 0.1 mg(Tl)/m3 (skin) ACGIH TLV TWA 0.1 mg(Tl)/m3 (skin) SAFETY PROFILE Poison by ingestion. When heated to decomposition it emits toxic fumes of Tl. See also THALLIUM COMPOUNDS. 

When heated to decomposition it emits very toxic fiimes of Tl and Se. See also THALLIUM COMPOUNDS and SELENIUM COMPOUNDS. 

A cellular toxicant like arsenic. Fatal human dose is about 500 mg of thallium. Intake of thallium causes depilation. Many reported fatalities. An experimental teratogen. When heated to decomposition it emits very toxic fumes of SOx and Tl. Pesticide for control of rats, moles, and house mice. See also THALLIUM COMPOUNDS and SULFATES. 

Greal cart must be taken when using tins methoTTology because mercury and thallium compounds are extremely toxic. 

All thallium compounds are highly toxic and must be handled with utmost care. 

Thallium is the largest and the heaviest element of the group 13 family. The metal and its compounds are dangerously toxic, even at low levels. It is a cumulative poison, and the lethal dose is considered to be about 13 mg of thallium for each kg of human body weight (or less than Ig of a thallium compound in a single ingestion). The ability of free T1(I) ions in aqueous... 

---