NRDC v. E. Scott Pruitt et al. (Enlist Duo)


In January 2017, the U.S. Environmental Protection Agency approved a new pesticide called Enlist Duo—despite its serious risks to people and monarch butterflies—to be used on three major crops (corn, soy, cotton) across 34 states. So in March of that year, NRDC challenged the EPA’s reckless decision in federal court.

Formulated by Dow AgroSciences, Enlist Duo combines the active ingredients glyphosate and 2,4-D. Both of these chemicals have been linked to serious health risks. Yet, in deciding whether to approve Enlist Duo, the EPA disregarded more than two decades of science on non-cancer health risks posed by glyphosate, including studies linking it to increased risk of kidney toxicity and birth defects.

It’s not just human health that may be in danger. Enlist Duo also threatens the North American monarch butterfly, an iconic species famed for its annual migration across the continent. After undergoing a severe population decline in recent years, the monarch’s numbers are so precariously small that experts—including those at the U.S. Department of Agriculture—have warned that the monarch migration may be coming to an end. Milkweed, the monarch caterpillar’s sole food source, has been decimated by the sharp increase in the use of herbicides on herbicide-resistant crops. Enlist Duo is specifically designed to kill milkweed, among other target plants. The pesticide is also intended to be used on crops genetically engineered to resist it, meaning that farmers can apply more of this toxic pesticide across a longer portion of the growing season. Enlist Duo’s ongoing destruction of milkweed habitat across the monarch’s breeding grounds puts the species at further risk of eradication.  

On July 22, 2020, the U.S. Court of Appeals for the Ninth Circuit confirmed that the EPA had violated the law. The court ruled that the EPA failed to consider harm to monarch butterflies from the destruction of milkweed in agricultural fields in registering the herbicide Enlist Duo for widespread use—and ordered EPA to address this risk. While the ruling unfortunately allows the herbicide to remain on the market in the meantime, we expect EPA to move quickly so the court can promptly rule on the agency’s new decision. We’ll be keeping a close eye on updates. 

Last Updated

July 23, 2020

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Court Ruling: EPA Failed to Assess Enlist Duo’s Impact on Monarch Butterflies Judges Send Federal Agency Back to the Drawing Board to Reassess Risk

WASHINGTON, DC – In a victory for NRDC (Natural Resources Defense Council), the U.S. Court of Appeals for the Ninth Circuit today decided the Environmental Protection Agency (EPA) failed to consider harm to monarch butterflies from the destruction of milkweed in agricultural fields in registering the herbicide Enlist Duo for widespread use. The court ordered EPA to address this risk but has allowed Enlist Duo to remain on the market in the meantime.

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