3D model (JSmol)
CompTox Dashboard (EPA)
|Molar mass||229.65 g/mol|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is ?)(|
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.: p. 79
The toxicity of ethylmercury is well studied. 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. 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.
Public health concerns
Concerns based on extrapolations from methylmercury caused thiomersal to be removed from U.S. childhood vaccines, starting in 1999, but remains in all multi-dose vaccines and flu shots (though many single use vaccines with no thimerosal are available). Clarkson has 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, Clarkson has 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.
References and notes
- Clarkson, Thomas W.; Magos, Laszlo (September 2006). "The toxicology of mercury and its chemical compounds". Critical Reviews in Toxicology. 36 (8): 609–62. doi:10.1080/10408440600845619. PMID 16973445. S2CID 37652857.
- Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
- Elschenbroich C (2016). "Main-Group Organometallics [§6.2.3 Organomercury Compounds]". Organometallics (3rd ed.). New York, NY: John Wiley & Sons. pp. 78–86. ISBN 978-3-527-80514-3. Retrieved 13 February 2017.
- Counter, S.Allen; Buchanan, Leo H. (2004). "Mercury exposure in children: A review". Toxicology and Applied Pharmacology. 198 (2): 209–230. doi:10.1016/j.taap.2003.11.032. PMID 15236954.
- Clarkson TW, Vyas JB, Ballatori N (October 2007). "Mechanisms of mercury disposition in the body". American Journal of Industrial Medicine. 50 (10): 757–64. doi:10.1002/ajim.20476. PMID 17477364.
- Clifton JC (April 2007). "Mercury exposure and public health". Pediatric Clinics of North America. 54 (2): 237–69, viii. doi:10.1016/j.pcl.2007.02.005. PMID 17448359.[verification needed]
- "Weekly Epidemiological Record, vol. 87, 30 (pp 277–288)". WHO. 2012-07-27. Retrieved 2020-05-10.
- Research, Center for Biologics Evaluation and (2019-04-05). "Thimerosal and Vaccines". FDA.
- Mitchell WJ (2005). "Carbohydrate assimilation by saccharolytic clostridia". Environmental Health Perspectives. 143 (3): 245–50. doi:10.1289/ehp.113-a543. PMC 1280369.
- DHHS ATSDR, US (March 2013). "Addendum to the Toxicological Profile for Mercury (Alkyl and Dialkyl Compounds)" (PDF). CDC.gov. Retrieved 13 February 2017.
- EPA, OA, US (9 September 2015). "Thimerosal in Vaccines". EPA.gov. Retrieved 13 February 2017.
- Santos JC, da Silva IM, Braga TC, de Fátima Â, Figueiredo IM, Santos JC (February 2018). "Thimerosal changes protein conformation and increase the rate of fibrillation in physiological conditions: Spectroscopic studies using bovine serum albumin (BSA)". International Journal of Biological Macromolecules. 113: 1032–1040. doi:10.1016/j.ijbiomac.2018.02.116. PMID 29476861.