Methyl mercury compounds

The solubility of organomercury compounds depends primarily on the nature of the X group nitrates and sulfates tend to be salt-like and relatively water-soluble, whereas chlorides are covalent, nonpolar compounds of low water solubility. Methyl mercury compounds tend to be more volatile than other organomercury compounds. 

Organoarsenic compounds have been of importance in human toxicology but have not as yet received much attention in regard to environmental effects. Like methyl mercury compounds, they are both synthesized in the environment from inorganic forms and released into the environment as a consequence of human activity (Environmental Health Criteria 18). They can cause neurotoxicity. 

Horvat, M., Bloom, N.S., and Liang, L., Comparison of distillation with other current isolation methods for determination of methyl mercury compounds in low level environmental samples, Part II, Water Analytica Chimica Acta, 282, 153-168, 1993. 

Mercury occurs in soils predominantly in the +2 oxidation state. Elemental Hg in the atmosphere is oxidized to Hg + and deposited in rainfall. It is a strong chalcophile and under anaerobic conditions forms the extremely insoluble sulfide cinnabar (HgS, pK = 52.7). Nonetheless it is not entirely immobilized under anaerobic conditions because it is reduced to volatile Hg° or methylated to volatile methyl mercury compounds by microbial action, and so returned to the atmosphere. The methylation is mediated by various bacteria, especially methanogens, through the reactions ... 

Other volatile methyl mercury compounds, such as (C6H5)2Hg, are also formed. The CH3Hg+ unit is very inert with respect to decomposition. Therefore, once formed, methyl mercury compounds are not readily demethylated. The biogeochemistry of Hg in the environment is reviewed by Ridley et al (1977) and Mason et al (1993). 

Junghans RP A review of the toxicity of methyl mercury compounds with application to occupational exposures associated with laboratory uses. Environ Res 31 1-31, 1983... 

Fish Hg Mass spectrometry. Activation analysis. Extraction identification and determination of methyl-mercury compounds 90)... 

Newsome [6] determined methyl mercury compounds in wheat flour and ground oats by extraction with benzene-formic acid followed by purification and gas-liquid chromatography. Interfering substances were removed from the extracts by column chromatography on silicic acid and partitioning with cysteine acetate solution. The method is sensitive in the 0.01-0.9 ppm range with a recovery of generally better than 95%. 

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]. 

From a toxicological point of view, alkyl-Hg, especially methyl mercury compounds, are usually more toxic than inorganic species (HgCl2, Hg , Hg ). The same is true for tin. 

R. Pongratz, K. G. Heumann, Determination of concentration profiles of methyl mercury compounds in surface waters of polar and other remote oceans by GC-AFD, Int. J. Environ. Anal. Chem., 71 (1998), 41-56. 

Hunter D, Bomford RR, Russell DS. 1940. Poisoning by methyl mercury compounds. Quart J Med 9 193-213. 

Mercury-containing mlldewcides have come into disfavor due to the high toxicity of methyl mercury compounds to humans. 

Ahlmark A Poisoning by methyl mercury compounds. British Journal of Industrial Medicine 5 117-119,1948... 

Human exposure is either to mercury vapor or methyl mercury compounds [25]. See also chapter 26. 

Rowland I, Davles M and Grasso P (1977) Biosynthesis of methyl mercury compounds by the intestined flora of the rat. Arch Environ Health 32 24-28. 

Westdo, G. (1966) Determination of methylmercury compounds in foodstuffs. I. Methyl-mercury compounds in fish. Identification and determination. Acta Chem. Scand., 20, 2131-2137. 

G. Westoo, Determination of Methyl Mercury Compounds in Food-... 

Davies IM, Russell R (1988) The influence of dissolved selenium compounds on the accumulation of inorganic and methylated mercury compounds from solution by the mussel Mytilus edulis and the plaice Pleuronectesplatessa. Sci Total Environ 68 197-205 Dehnen W, Tomingas R, Roos J (1973) A modified method for assay of benzo[a]pyrene hydroxylase. Anal Biochem 53 378-383... 

Some Technical Improvements in the Selective Measurement for Methyl-mercury Compounds in Blood by Gas Chromatography... 

Phenyl mercury compounds are more efficiently absorbed in the gastrointestinal tract of the rat than inorganic mercuric mercury, but less effectively than methyl mercury compounds (Ellis and Fang, 1967). Figures concerning man are not available. Absorbed phenyl mercury is distributed in blood similarly to methyl mercury, i.e. about 90% is present in the erythrocytes (Berlin, 1963 b). Initially, a large pro-... 

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