Ethylmercury Explained

Ethylmercury (sometimes ethyl mercury) is a cation composed of an organic CH3CH2— species (an ethyl group) bound to a mercury(II) centre, making it a type of organometallic cation, and giving it a chemical formula C2H5Hg+. The main source of ethylmercury is thimerosal.

Synthesis and structure

Ethylmercury (C2H5Hg+) is a substituent of compounds: it occurs as a component of compounds of the formula C2H5HgX where X = chloride, thiolate, or another organic group. Most famously X = the mercaptide group of thiosalicylic acid as in thiomersal. In the body, ethylmercury is most commonly encountered as derivatives with a thiolate attached to the mercury. In these compounds, Hg(II) has a linear or sometimes trigonal coordination geometry. Given the comparable electronegativities of mercury and carbon, the mercury-carbon bond is described as covalent.[1]

Toxicity

The toxicity of ethylmercury is well studied.[2] Like methylmercury, ethylmercury distributes to all body tissues, crossing the blood–brain barrier and the placental barrier, and ethylmercury also moves freely throughout the body.[3] Risk assessment for effects on the human nervous system have been made by extrapolating from dose-response relationships for methylmercury. Estimates have suggested that ethylmercury clears from blood with a half-life of 3—7 days in adult humans; however, this area has not been well studied.[4] [5]

Public health concerns

See main article: Thiomersal and vaccines. Concerns based on extrapolations of the effect of methylmercury caused thimerosal to be removed from U.S. childhood vaccines in 1999, but it remains in use in all multi-dose vaccines and flu shots (though many single use vaccines without thimerosal are available).[6] Researchers have argued that risk assessments based on methylmercury were overly conservative in light of observations that ethylmercury is eliminated from the body and the brain significantly faster than methylmercury. Moreover, the same researchers have argued that inorganic mercury metabolized from ethylmercury, despite its much longer half-life in the brain, is much less toxic than the inorganic mercury produced from mercury vapor, for reasons not yet understood.[7]

See also

Further reading

External links

Notes and References

  1. Book: Elschenbroich, Christoph . vanc . 2016 . Organometallics . 3rd . New York, NY . John Wiley & Sons . 978-3-527-80514-3 . Main-Group Organometallics [§6.2.3 Organomercury Compounds] . 78–86 . 13 February 2017.
  2. 10.1016/j.taap.2003.11.032. 15236954. Mercury exposure in children: A review. Toxicology and Applied Pharmacology. 198. 2. 209–230. 2004. Counter. S.Allen. Buchanan. Leo H..
  3. Clarkson TW, Vyas JB, Ballatori N . Mechanisms of mercury disposition in the body . American Journal of Industrial Medicine . 50 . 10 . 757–64 . October 2007 . 17477364 . 10.1002/ajim.20476 .
  4. Clifton JC . Mercury exposure and public health . Pediatric Clinics of North America . 54 . 2 . 237–69, viii . April 2007 . 17448359 . 10.1016/j.pcl.2007.02.005 .
  5. Web site: Weekly Epidemiological Record, vol. 87, 30 (pp 277–288). https://web.archive.org/web/20141019093421/http://www.who.int/wer/2012/wer8730/en/. dead. October 19, 2014. 2012-07-27. WHO. 2020-05-10.
  6. Research. Center for Biologics Evaluation and. 2019-04-05. Thimerosal and Vaccines. FDA. en.
  7. The toxicology of mercury and its chemical compounds . Critical Reviews in Toxicology . 36 . 8 . 609–62 . September 2006 . 16973445 . 10.1080/10408440600845619 . 37652857 . Clarkson . Thomas W. . Magos . Laszlo .

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