Please turn off your ad blocker to properly view this site. Thank you!
Protecting Our Food, Farms & Environment
toggle menu
Pacific Northwest
Hawai'i CFS

Court of Appeals Decision on EPA Approval of Dow's Enlist Duo Pesticide

July 22, 2020
Center for Food Safety

Statement from George Kimbrell, Legal Director of Center for Food Safety and Lead Counsel in the Case:

Today's Ninth Circuit Court of Appeals decision correctly held that the U.S. Environmental Protection Agency (EPA) failed to protect Monarch butterflies in registering Dow's toxic pesticide Enlist Duo. For this reason the panel held the registration illegal and sent it back to EPA for further study. These iconic butterflies are in steep decline from the overuse of glyphosate-based pesticides like Enlist Duo, which kill off the farm field milkweed plants that are indispensable for the butterfly's reproduction. In response to a petition spearheaded by Center for Food Safety, the Monarch is under consideration as a threatened species under the Endangered Species Act. Unfortunately, the Court erred in concluding that the EPA approval was otherwise lawful and allowing the pesticide to stay on the market.

Most gravely, the panel majority absolved EPA's wrongful refusal to seek the guidance of the expert wildlife agencies on Enlist Duo's effects on over 500 plant and animal species that are protected under the Endangered Species Act; EPA itself admitted that these species will be exposed to Enlist Duo. The Court allowed EPA to forego consultation with the expert wildlife agencies despite the National Academy of Sciences' finding that the way EPA went about reviewing endangered species risks for Enlist Duo was "scientifically indefensible." As Judge Watford explained in his dissent in the ruling, the Endangered Species Act requires agencies use the "best available science" to address risks to species, not risk irreparable species extinction by using approaches and data it knows are outdated and scientifically indefensible. The panel majority's unprecedented decision is contrary to controlling law and established science, and Center for Food Safety is analyzing all legal options, including seeking a full court rehearing.


Enlist Duo is a combination of glyphosate and 2,4-D, to be sprayed on corn, cotton, and soybeans that are genetically engineered by Dow with resistance to both pesticides.

National Cancer Institute scientists highlighted 2,4-D specifically as associated with a two- to eight-fold increase in non-Hodgkin's lymphoma. The International Agency for Research on Cancer of the World Health Organization classified 2,4-D as a possible carcinogen to humans and glyphosate as a probable carcinogen to humans.

In early 2017, EPA dramatically expanded approval of Enlist Duo use to 34 states and for use on cotton, only one year after a Court sent back EPA's previous approval. The two chemicals in Enlist Duo do more damage when used together than the net damage they do when used separately.

Dow markets Enlist Duo and its companion Enlist crops as a quick fix for the "superweeds" epidemic created by "Roundup Ready" crops, genetically engineered to withstand what would otherwise be a toxic dose of the herbicide glyphosate, the active ingredient in Monsanto's Roundup. Repeated use of Roundup on these crops has resulted in the proliferation of glyphosate-resistant superweeds which now infest over a hundred million acres of U.S. farmland. These superweeds now require an even more toxic combination of herbicides, like Enlist Duo, to take them out, driving a dangerous spiral of increasing weed resistance and pesticide use. The U.S. Department of Agriculture conservatively estimates that use of Enlist Duo on U.S. corn and soybean will increase the use of 2,4-D by 200 to 600 percent.

The plaintiff coalition in this case is Center for Food Safety, Center for Biological Diversity, Beyond Pesticides, Pesticide Action Network North America, National Family Farm Coalition, and Family Farm Defenders, represented by legal counsel from Center for Food Safety.

Related News