EPA has cleared the way for the herbicide Enlist Duo—a combination of 2,4-D and glyphosate—to be used on genetically engineered corn and soybeans in more than a dozen U.S. states. The agency is also proposing to allow the controversial mixture to be used on cotton and to expand the number of states where it can be used. U.S. regulators first approved Enlist Duo for use on corn and soybeans in 2014, but subsequently asked a federal court to overturn the approval. The agency claimed that the herbicide’s maker, Dow AgroSciences, withheld information suggesting synergistic toxicity effects between the two ingredients. EPA reviewed additional data submitted by Dow and announced on Nov. 1 that regulators found no such effects. Dow had reported synergistic effects in a patent application for Enlist Duo, but now says that the claim was based on limited information. Additional data confirm the two ingredients do not amplify each other’s toxicity, Dow says. Environmental groups that challenged EPA’s approval of Enlist Duo are outraged by the agency’s decision. “This proposal ignores the available data and will potentially harm our environment,” says Nathan Donley of the Center for Biological Diversity, one of the plaintiffs. EPA expects to make a final decision in early 2017.