October 16, 2012
Image of Thiamethoxam 3D Image of Thiamethoxam

Thiamethoxam is a broad-spectrum neonicotinoid insecticide. It was developed by Syngenta, which had to settle a patent suit by Bayer before marketing it. Thiamethoxam acts by direct contact with insects and by insects' consumption of treated plants. Recently, M. Henry and colleagues at the French agency that combines the functions of FDA, EPA, and OSHA found that thiamethoxam harms honeybees. For this reason, it may soon be banned in France.

MOTW update: June 03, 2019

Clothianidin and thiamethoxam were the Molecules of the Week for February 17, 2014 and October 15, 2012, respectively. Both are neonicotinoid insecticides that during the past decade have come under regulatory pressure because they are toxic to honeybees. Finally, this past week, the US Environmental Protection Agency canceled the registrations for 12 formulations that contain one or the other of these pesticides.

MOTW update: May 14, 2018

Clothianidin, imidacloprid, and thiamethoxam were the Molecules of the Week for February 17, 2014, August 25, 2014, and October 15, 2012, respectively. All three are neonicotinoid pesticides, and all three have been found to contribute to the worldwide die-off of honeybees. Use of these pesticides has been gradually restricted during the past several years, but now the European Union is about to ban them from all outdoor uses. Will the United States follow suit?

MOTW update:
February 17, 2020

Thiamethoxam is a nicotinoid pesticide that pose neurotoxic risks to humans and wildlife, especially honeybees. Nonetheless, in an interim decision announced in January, the US Environmental Protection Agency is allowing continued use of the pesticides, with some restrictions yet to be announced. This action is in contrast to the European Commission’s 2018 ban on these and other nicotinoids for outdoor use.

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