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EPA Revokes Approval of Enlist Duo Weed Killer Due to Butterfly Deaths

EPA Revokes Approval of 'Synergistic' Pesticide Enlist Duo Due to Butterfly Deaths

The Environmental Protection Agency (EPA) has decided to revoke its approval of Dow AgroSciences' product Enlist Duo after determining that the product is “likely significantly more harmful than initially believed,” according to a press release published by the Center for Biological Diversity. Specifically, the chemical appears to be linked to monarch butterfly deaths.

The EPA appealed to the courts last week to reverse its original decision, citing a discovery of new information as the reason behind the change.

When the EPA originally approved Enlist Duo, Dow had argued that the combination of glyphosate (the active ingredient in Roundup) and 4-D was no more toxic than the two chemicals separately. However, when applying for a patent, Dow told the U.S. Patent and Trademark Office that the chemical combination would offer “synergistic herbicide weed control,” something that environmental activists had cited as a possible problem when the product was originally approved (including over 200,000 people who signed a petition to ask the company to stop selling the product), NPR reported.

“EPA can no longer be confident that Enlist Duo will not cause risks of concern to nontarget organisms, including those listed as endangered, when used according to the approved label,” the agency said in its filing to the United States Court of Appeals for the Ninth Circuit in San Francisco, reports the New York Times. The EPA originally approved the herbicide in November 2014.

Enlist Duo is intended to be used on GMO corn and soybean strains that have been genetically engineered to tolerate it. Glyphosate has also been cited as the chief cause of the decline in monarch butterflies, according to a press release from the Natural Resources Defense Council.

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From the Organic Authority Files

"Removing this dangerous chemical from the market is a key step in protecting sensitive native plants and monarch butterflies, which have been further threatened by its impact on milkweed, the plant they need to survive," said Sylvia Fallon, Senior Scientist at the NRDC. "We are delighted by this news, but also troubled that the EPA overlooked this information initially."

In a press release published Wednesday, Dow claimed that Enlist Duo should still reach markets for the 2016 growing season.

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Monarch butterfly image via Shutterstock

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