Ethylmercury: Difference between revisions
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== Toxicity == | == Toxicity == | ||
The toxicity of ethylmercury is well studied.<ref name="Mercury exposure in children: A review">{{cite journal|doi=10.1016/j.taap.2003.11.032|pmid=15236954|title=Mercury exposure in children: A review|journal=Toxicology and Applied Pharmacology|volume=198|issue=2|pages=209–230|year=2004|last1=Counter|first1=S.Allen|last2=Buchanan|first2=Leo H.|bibcode=2004ToxAP.198..209C }}</ref><ref name=Clarkson/> 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.<ref name=pmid17477364>{{cite journal | vauthors = Clarkson TW, Vyas JB, Ballatori N | title = Mechanisms of mercury disposition in the body | journal = American Journal of Industrial Medicine | volume = 50 | issue = 10 | pages = 757–64 | date = October 2007 | pmid = 17477364 | doi = 10.1002/ajim.20476 }}</ref> Risk assessment for effects on the human nervous system have been made by extrapolating from dose-response relationships for [[methylmercury]].<ref name=Clarkson/> Estimates have suggested that ethylmercury clears from blood with a [[half-life]] of | The toxicity of ethylmercury is well studied.<ref name="Mercury exposure in children: A review">{{cite journal|doi=10.1016/j.taap.2003.11.032|pmid=15236954|title=Mercury exposure in children: A review|journal=Toxicology and Applied Pharmacology|volume=198|issue=2|pages=209–230|year=2004|last1=Counter|first1=S.Allen|last2=Buchanan|first2=Leo H.|bibcode=2004ToxAP.198..209C }}</ref><ref name=Clarkson/> 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.<ref name=pmid17477364>{{cite journal | vauthors = Clarkson TW, Vyas JB, Ballatori N | title = Mechanisms of mercury disposition in the body | journal = American Journal of Industrial Medicine | volume = 50 | issue = 10 | pages = 757–64 | date = October 2007 | pmid = 17477364 | doi = 10.1002/ajim.20476 }}</ref> Risk assessment for effects on the human nervous system have been made by extrapolating from dose-response relationships for [[methylmercury]].<ref name=Clarkson/> Estimates have suggested that ethylmercury clears from blood with a [[half-life]] of 3–7 days in adult humans.<ref name=pmid17448359>{{cite journal | vauthors = Clifton JC | title = Mercury exposure and public health | journal = Pediatric Clinics of North America | volume = 54 | issue = 2 | pages = 237–69, viii | date = April 2007 | pmid = 17448359 | doi = 10.1016/j.pcl.2007.02.005 }}{{verification needed|date=February 2017}}</ref><ref>{{Cite web|title=Weekly Epidemiological Record, vol. 87, 30 (pp 277–288)|url=https://www.who.int/wer/2012/wer8730/en/|archive-url=https://web.archive.org/web/20141019093421/http://www.who.int/wer/2012/wer8730/en/|url-status=dead|archive-date=October 19, 2014|date=2012-07-27|website=WHO|access-date=2020-05-10}}</ref> In monkeys, it clears from brain tissue with a [[half-life]] of 24 days and blood in 7 days.<ref name="monkeys">{{Cite journal |last=Burbacher |first=Thomas M. |year=2005 |title=Comparison of Blood and Brain Mercury Levels in Infant Monkeys Exposed to Methylmercury or Vaccines Containing Thimerosal |journal=Environmental Health Perspectives |language=en |volume=113 |issue=8 |pages=1015–1021 |doi=10.1289/ehp.7712 |issn=0091-6765 |pmc=1280342 |pmid=16079072 |bibcode=2005EnvHP.113.1015B |quote="See researchgate.net/figure/A-semilogarithmic-plot-of-washout-of-total-Hg-in-blood-and-the-brain-after-four-weekly-im_fig6_7681091"}}</ref> | ||
It is a fungicide but has been banned from use in the U.S. on food grain and even on seeds only used to grow crops.<ref name=EPA-TEACH-children>{{Cite web |title=Organic Mercury--TEACH Chemical Summary--U.S. EPA, Toxicity and Exposure Assessment for Children's Health| url=https://archive.epa.gov/region5/teach/web/pdf/mercury_org_summary.pdf|quote="Methyl- and ethylmercury have been used previously as fungicides on seeds used for growing crops, but such use is currently cancelled in the U.S."}}</ref> | It is a fungicide but has been banned from use in the U.S. on food grain and even on seeds only used to grow crops.<ref name=EPA-TEACH-children>{{Cite web |title=Organic Mercury--TEACH Chemical Summary--U.S. EPA, Toxicity and Exposure Assessment for Children's Health| url=https://archive.epa.gov/region5/teach/web/pdf/mercury_org_summary.pdf|quote="Methyl- and ethylmercury have been used previously as fungicides on seeds used for growing crops, but such use is currently cancelled in the U.S."}}</ref> | ||
Latest revision as of 13:30, 29 June 2025
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.[1]
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.[2] 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.[3]Template:Rp
Toxicity
The toxicity of ethylmercury is well studied.[4][1] 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.[5] Risk assessment for effects on the human nervous system have been made by extrapolating from dose-response relationships for methylmercury.[1] Estimates have suggested that ethylmercury clears from blood with a half-life of 3–7 days in adult humans.[6][7] In monkeys, it clears from brain tissue with a half-life of 24 days and blood in 7 days.[8]
It is a fungicide but has been banned from use in the U.S. on food grain and even on seeds only used to grow crops.[9]
Public health concerns
Script error: No such module "Labelled list hatnote". 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).[10] 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.[1] 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.[1]
See also
References and notes
Further reading
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External links
- EPA Organic Mercury TEACH Chemical Summary, 2007.
- EPA Chemistry Dashboard, Ethyl Mercury Ion, 2017.
- ATSDR Toxicological Profile for Mercury, search "Organic Mercury".
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