meth·​yl·​mer·​cury ˌme-thəl-ˈmər-kyə-rē How to pronounce methylmercury (audio)
: 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

Example Sentences

Recent Examples on the Web The mummichog’s remarkable survival abilities were first recognized in the early 1970s, when the marine ecologist Judith S. Weis and her husband, Peddrick, decided to use the species to investigate the effects of the toxic chemical methylmercury on marine life. Carrie Arnold, The Atlantic, 15 Mar. 2021 Science of the Total Environment, 2008; 400: 75-92. Yaginuma-Sakurai K., Murata K., Iwai-Shimada M., Kurokawa N., Tatsuta N., Satoh H. Hair-to-blood ratio and biological half-life of mercury: experimental study of methylmercury exposure through fish consumption in humans. Alice Chi Phung, Discover Magazine, 2 Feb. 2016 The oceans absorb this airborne mercury, and microorganisms convert the metal into a form called methylmercury. Roni Dengler, Discover Magazine, 8 Aug. 2019 The most common, reliable, and affordable treatment is coagulation/filtration, which uses aluminum sulfate to consolidate both inorganic mercury and methylmercury into a solid that can be removed from the water and summarily disposed of at a hazardous waste site. Gia Mora, Treehugger, 8 Mar. 2023 Artisanal miners in the region also use methylmercury to separate gold from other substances, which contaminates water, soil, and the plants and animals that depend on them. Jill Langlois, Smithsonian Magazine, 21 Feb. 2023 As the waterlogged plants and trees decay, the resulting low-oxygen environment allows bacteria to thrive, and those microorganisms combine elemental or inorganic mercury with carbon to create methylmercury. Gia Mora, Treehugger, 8 Mar. 2023 But methylmercury that has started to accumulate in the region thanks to human endeavors is more dangerous. Jill Langlois, Smithsonian Magazine, 21 Feb. 2023 Most of the mercury was in the most toxic form to humans, methylmercury, thus such an increase is troubling, even though the 2008 levels were still considered safe to consume. Christie Wilcox, Discover Magazine, 3 Feb. 2015 See More

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Word History

First Known Use

1915, in the meaning defined above

Time Traveler
The first known use of methylmercury was in 1915

Dictionary Entries Near methylmercury

Cite this Entry

“Methylmercury.” Dictionary, Merriam-Webster, Accessed 1 Jun. 2023.

Medical Definition


ˌmeth-əl-ˈmər-kyə-rē, British also ˌmē-ˌthīl-
plural methylmercuries
: 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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