Toxicity organomercury compounds

Thus, the synthesis of triphenylscandium is a salt-elimination reaction (or metathesis) whilst the route for the lanthanide phenyls involves a redox reaction. The former has the problem of producing LiCl, which is often significantly soluble in organic solvents and contaminates the desired product, whilst the latter involves disposal of mercury waste, as well as handling toxic organomercury compounds. 

The high vapor pressure of metallic mercury is the main reason for the occupational burden, wherever mercury is mined, melted, refined, treated, or recycled [2]. Especially dangerous are the production and treatment of highly toxic organomercury compounds such as methylmercury [14],... 

The acute toxicity of different types of organomercury compounds to mammals,... 

Since the 1950s, diuretic therapy has changed dramatically. Earlier, the major diuretics were acidforming salts, xanthines, organomercurial compounds, and carbonic anhydrase inhibitors. Either because of toxicity or lack of efficacy, these agents are rarely if ever used. 

A number of organomercury compounds are known. These compounds and their toxicities are discussed further in Chapter 12. 

Mercury contaminated foodstuffs and water supplies are a concern because of the extreme toxicity of the element and its compounds. Elemental mercury is used in the production of chlorine gas, and organomercury compounds formerly found use as pesticides and fungicides. Alkyl mercury compounds are of greatest concern since they do not degrade readily, and methyl mercury compounds concentrate in fish lipid tissue [9]. Pregnant women are at greatest risk since methyl mercury readily crosses the placenta, affecting the fetus [6]. 

All organomercury compounds are extremely toxic, as they pass through cell membranes much more easily than inorganic forms. 

Mercury. Mercury Is a classic heavy metal occupational toxicant studied by Paracelsus and popularized in Lewis Carol s Alice in Wonderland. Both elemental and organomercury compounds are of great interest to Industrial hygienists. Elemental mercury is still routinely determined from acidic KMnO collection by dithizone complexation at 515 nm (6) (Table VI ). Surprisingly, Hg is not Included In P CAM 173. Elemental mercury has been determined by flameless AAS (P CAM 165) for urine,... 

Of the methods we have seen for Markovnikov hydration of alkenes, oxymercuration-demercuration is most commonly used in the laboratory. It gives better yields than direct acid-catalyzed hydration, it avoids the possibility of rearrangements, and it does not involve harsh conditions. There are also disadvantages, however. Organomercurial compounds are highly toxic. They must be used with great care and then must be disposed of properly. 

Thimerosal (Merthiolate) has been used as a topical antiseptic for many years. Its antimicrobial effect is mostly due to the toxicity of the mercury atom that is bound and stabilized by the thiol group of ortho-mercaptobenzoic acid. The carboxylate salt of the acid is used to enhance solubility of this organomercurial compound. 

Many human tragedies have been caused by organomercury compounds in food. In the twentieth century, mercury compounds, usually the most toxic types, were applied as fungicides to seeds. Large-scale poisoning occurred in Iraq in 1971-1972 as a result of an appalling error, when seeds contaminated with Hg compounds were sold for consumption. After that event, the application of Hg compounds in farming practice declined, but a fair amount of the element remains in the soil. 

---