meth·​yl·​mer·​cury | \ ˌme-thəl-ˈmər-kyə-rē How to pronounce methylmercury (audio) , -ˈmər-k(ə-)rē \

Definition of methylmercury

: any of various toxic compounds of mercury containing the complex CH3Hg− that often occur as pollutants which accumulate in living organisms (such as fish) especially in higher levels of a food chain

Examples of methylmercury in a Sentence

Recent Examples on the Web Three years after researchers stopped adding mercury, the concentration of methylmercury in the water dropped by 81 percent. Rasha Aridi, Smithsonian Magazine, 20 Dec. 2021 Most of the fish are safe to eat, at least occasionally; the state warns against eating certain species with high levels of toxins including PCBs, or methylmercury. Morgan Greene,, 2 Sep. 2021 Predatory fish — which build up methylmercury by eating other fish — include: all species of black bass and gar, striped bass, white bass, hybrid striped bass, walleye, sauger, saugeye, flathead catfish, muskellunge and northern pike. Morgan Greene,, 19 Aug. 2021 Older fish are high in the neurotoxin methylmercury, which is especially dangerous to children and pregnant women. Terry Spencer, Star Tribune, 12 May 2021 Dr Colón-Rodríguez, who is currently a postdoctoral scientist at the University of California, Davis, has focused on the effects of an environmental toxin called methylmercury (MeHg) on the human nervous system. Andrew Wight, Forbes, 17 Mar. 2021 Back in the lab, the couple spawned them and raised the embryos in water containing methylmercury. Carrie Arnold, The Atlantic, 15 Mar. 2021 Once deposited, certain microorganisms can change mercury into more dangerous methylmercury, a highly toxic form that builds up in fish, shellfish and animals that eat fish, in a process known as bioaccumulation., 28 Dec. 2020 Initial re-analysis of 717’s brain turned up a mix of carbon-free, inorganic mercury molecules and methylmercury. Theresa Machemer, Smithsonian Magazine, 26 Mar. 2020

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'methylmercury.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of methylmercury

1915, in the meaning defined above

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The first known use of methylmercury was in 1915

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Dictionary Entries Near methylmercury

methyl isocyanate


methyl methacrylate

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Last Updated

30 Dec 2021

Cite this Entry

“Methylmercury.” Dictionary, Merriam-Webster, Accessed 25 Jan. 2022.

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More Definitions for methylmercury


meth·​yl·​mer·​cury | \ ˌmeth-əl-ˈmər-kyə-rē, British also ˌmē-ˌthīl- \
plural methylmercuries

Medical Definition of methylmercury

: any of various toxic compounds of mercury containing the complex CH3Hg− that often occur as pollutants formed as industrial by-products or pesticide residues, tend to accumulate in living organisms (as fish) especially in higher levels of a food chain, are rapidly and easily absorbed through the human intestinal wall, and cause neurological dysfunction in humans — see minamata disease


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