chlor·​pyr·​i·​fos | \ klȯr-ˈpir-ə-fäs How to pronounce chlorpyrifos (audio) , -ˈpī-rə \

Definition of chlorpyrifos

: a toxic crystalline organophosphate pesticide C9H11Cl3NO3PS that inhibits acetylcholinesterase and is used to control insect pests and ticks

Examples of chlorpyrifos in a Sentence

Recent Examples on the Web The agency had banned chlorpyrifos for household uses in 2000, but allowed agricultural producers to continue using it. Devan Cole, CNN, 18 Aug. 2021 The European Union, Canada and some states including California, Hawaii, New York, Maryland, and Oregon have restricted application of chlorpyrifos on foods. John Flesher,, 18 Aug. 2021 The ban would stop the use of the pesticide chlorpyrifos on all food, the agency said Wednesday. Timothy Puko, WSJ, 18 Aug. 2021 Scientific studies have shown that chlorpyrifos damages the brains of fetuses and children. Matthew Daly, ajc, 29 Apr. 2021 Environmental groups said a ban of chlorpyrifos is long overdue. Matthew Daly, ajc, 29 Apr. 2021 Pesticide manufacturers, including Dow Chemical, and agricultural groups filed arguments supporting the EPA and said chlorpyrifos was both safe and effective. Bob Egelko, San Francisco Chronicle, 29 Apr. 2021 More than 1 million pounds of chlorpyrifos are sold each year in Minnesota, according to the Minnesota Department of Agriculture. Greg Stanley, Star Tribune, 22 Mar. 2021 Burd said petitions have been filed over controversial pesticides in the past, including chlorpyrifos, a pesticide linked to brain damage in children, and tetrachlorvinphos, another pesticide often used in pet collars. Johnathan Hettinger, USA TODAY, 8 Apr. 2021

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'chlorpyrifos.' 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 chlorpyrifos

1970, in the meaning defined above

History and Etymology for chlorpyrifos

chlor- + pyridine + -fos (alteration of phosphorus)

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The first known use of chlorpyrifos was in 1970

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Last Updated

25 Aug 2021

Cite this Entry

“Chlorpyrifos.” Dictionary, Merriam-Webster, Accessed 18 Oct. 2021.

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More Definitions for chlorpyrifos


chlor·​pyr·​i·​fos | \ -ˈpir-ə-fäs, -ˈpī-rə- How to pronounce chlorpyrifos (audio) \

Medical Definition of chlorpyrifos

: a toxic crystalline organophosphate pesticide C9H11Cl3NO3PS that inhibits acetylcholinesterase and is used to control insect pests and ticks


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