Ethylmercury

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Ethylmercury
Ethylmercury-2D.svg Ethylmercury-cation-3D-vdW.png
Identifiers
CAS number 21687-36-5 N
ChemSpider 5247 YesY
ChEBI CHEBI:33204 YesY
Jmol-3D images Image 1
Properties
Molecular formula C2H5Hg+
Molar mass 229.65 g/mol
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
Infobox references

Ethylmercury (sometimes ethyl mercury) is a cation composed of an ethyl group bound to a mercury(II) centre; its chemical formula is C2H5Hg+. Ethylmercury is sometimes used as a generic term to describe organomercury compounds which include ethylmercury such as ethylmercury chloride and ethylmercury urea.

Ethylmercury is one of the metabolites of thiomersal,[1] which is used as a preservative in some vaccines. Thiomersal is the ethylmercury-releasing compound sodium ethylmercuric thiosalicylate, C9H9HgNaO2S, which is made from the combination of ethyl mercuric chloride, thiosalicylic acid, sodium hydroxide, and ethanol.

Toxicity[edit]

Unlike methylmercury, ethylmercury has not been found to bioaccumulate.[2] The toxicity of ethylmercury is not well studied - exposure standards based on methylmercury (such as those currently recommended by the United States Environmental Protection Agency) have not been demonstrated to be equivalent for ethylmercury.[3] Ethylmercury clears from blood with a half-life of about 18 days in adults. Ethylmercury is eliminated from the brain in about 14 days in infant monkeys. Risk assessment for effects on the nervous system have been made by extrapolating from dose-response relationships for methylmercury.[4] Methylmercury and ethylmercury distribute to all body tissues, crossing the blood–brain barrier and the placental barrier, and ethylmercury also moves freely throughout the body.[5] Concerns based on extrapolations from methylmercury caused thiomersal to be removed from U.S. childhood vaccines, starting in 1999. Since then, it has been found that ethylmercury is eliminated from the body and the brain significantly faster than methylmercury, so the late-1990s risk assessments turned out to be overly conservative.[4] Though inorganic mercury metabolized from ethylmercury has a much longer half-life in the brain, at least 120 days, it appears to be much less toxic than the inorganic mercury produced from mercury vapor, for reasons not yet understood.[4]

See also[edit]

References[edit]

  1. ^ "Thimerosal in vaccines". Center for Biologics Evaluation and Research, U.S. Food and Drug Administration. 2008-06-03. Retrieved 2008-07-25. 
  2. ^ NIAID Research on Thimerosal
  3. ^ Comparison of Blood and Brain Mercury Levels in Infant Monkeys Exposed to Methylmercury or Vaccines Containing Thimerosal. Environmental Health Perspectives 113(8):1015–1021; 2005.
  4. ^ a b c Clarkson TW, Magos L (2006). "The toxicology of mercury and its chemical compounds". Crit Rev Toxicol 36 (8): 609–62. doi:10.1080/10408440600845619. PMID 16973445. 
  5. ^ Clarkson TW, Vyas JB, Ballatori N (2007). "Mechanisms of mercury disposition in the body". Am J Ind Med 50 (10): 757–64. doi:10.1002/ajim.20476. PMID 17477364. 

External links[edit]