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Reps. Blumenauer, DeFazio, Other Members Call on EPA to Reevaluate Risks of Powerful Herbicide Before Reapproved

Feb 12, 2016
Press Release

Reps. Blumenauer, DeFazio, Other Members Call on EPA to Reevaluate Risks of Powerful Herbicide Before Reapproved


Washington, DC – This week, Representatives Earl Blumenauer (OR-03) and Peter DeFazio (OR-04) led 33 additional members of the U.S. House of Representatives in sending a letter to Environmental Protection Agency (EPA) Administrator Gina McCarthy expressing concerns regarding the potential negative health and environmental impacts of the herbicide Enlist Duo, and to request more information about EPA’s plan to reevaluate these risks before reapproving it for use.


Enlist Duo is an herbicide manufactured by Dow Chemical Co. that combines two powerful herbicides – 2,4-D and glyphosate – with proven health and environmental risks. A recent Chicago Tribune article details the registration of Enlist Duo by the EPA in October 2014 and raises significant questions about the agency’s approval process of Enlist Duo. In November 2015, the EPA asked the Ninth Circuit Court of Appeals to overturn its approval so that scientists could review new data regarding the impacts of the herbicides on endangered plant species. The court recently denied the request by EPA, leaving the registration decision to EPA for further consideration.


“This is part of a vicious cycle that is leading to more potent, dangerous chemicals being widely used on crops across the United States,” said Representative Blumenauer. “With the rise of herbicide-resistant genetically modified crops, herbicides are more widely sprayed causing weeds to grow more resistant – ultimately, requiring the application of even stronger herbicides. EPA must take action to make sure products entering the market to be used on our food are safe for human health and the environment.”


“The relentless pursuit of herbicide-resistant crops by corporate agriculture has created a toxic treadmill in our food system,” said Representative DeFazio. “It’s hard to believe that we are now debating whether or not a probable carcinogen such as glyphosate is safe to use on the food that we feed our children. The EPA needs to stand up against the pressures from the pesticide and agriculture industry and thoroughly assess the environmental and health impacts of this toxic chemical and reject it if the science shows there will be harm.”


“The questions Congress is asking EPA about Enlist Duo are the right ones,” said Mary Ellen Kustin, a senior policy analyst at the Environmental Working Group. “The EPA has not yet assessed this chemical cocktail in its entirety. Before combining the probable human carcinogen glyphosate with 2,4-D – a defoliant linked to non-Hodgkin’s lymphoma and other serious health problems – and drastically increasing the amount of these weed killers sprayed on American farmland, we need to know the risks this chemical cocktail has on nearby communities, especially children.”


“EPA took a step in the wrong direction by approving and expanding the use of Enlist Duo, a powerful combination of toxic pesticides that threaten wildlife, farmers, and human health. NRDC thanks Congressman Blumenauer, Congressman DeFazio, and all of the members who joined in investigating how the EPA’s greenlighting of Enlist Duo fits into its mission to protect public health and the environment,” said Sylvia Fallon, Senior Scientist with the Natural Resources Defense Council


Included below is the full text of the letter, and an electronic version of the letter with signatures can be found here.



February 11, 2016


Administrator Gina McCarthy

Environmental Protection Agency

1200 Pennsylvania Ave NW

Washington, DC 20004


Dear Administrator McCarthy:


We write to express our concerns regarding the findings in a recent Chicago Tribune report  on the Environmental Protection Agency's (EPA) review process for the herbicide Enlist Duo, and to request more information about EPA's plan to reevaluate Enlist Duo's health and environmental risks.

Enlist Duo is a new herbicide currently approved for use on herbicide-resistant corn and soybean crops.  Dow AgroSciences created Enlist Duo, a mixture of the weed killers glyphosate and 2,4-D, to combat so-called "superweeds" that have grown resistant to glyphosate alone.  As reported in the Chicago Tribune article, EPA registered Enlist Duo in October 2014 after reversing its previous analysis of certain health harms associated with exposure to 2,4-D.  We were concerned to learn that, during this process, EPA dismissed a key study linking 2,4-D to kidney abnormalities based on one scientist's analysis, and in doing so, effectively gave the green light for 41 times more of the chemical to enter the American diet than was previously allowed.

Given the widely-known adverse impacts of 2,4-D on human health and the environment, and with little understood about the implications of combining 2,4-D and glyphosate, EPA should use the utmost caution in assessing the safety of Enlist Duo before approving it for continued use.  We were pleased to learn of EPA's decision in November 2015 to ask a court to vacate the agency's approval of Enlist Duo, after Dow provided the agency with information regarding the synergistic effects of glyphosate and 2,4-D in Enlist Duo on threatened and endangered plants. The court denied that request, but did remand the registration decision to EPA for reevaluation.  We are troubled by reports that the EPA plans to conduct an extremely limited reanalysis of Enlist Duo's harms, questioning only whether a larger no-spray zone is needed to protect endangered plants that grow close to farm fields.   Moreover, these actions do not address questions about serious potential health risks brought to light by the Chicago Tribune.

At a minimum, while it considers the question of synergistic effects on remand, the EPA should evaluate at least two other major factors about Enlist Duo's environmental and health impacts.  First, the World Health Organization's International Agency for Research on Cancer recently published a groundbreaking finding that glyphosate is "probably carcinogenic to humans. "  EPA registered Enlist Duo without considering this cancer finding, and without looking at any studies on glyphosate's cancer risk that have been published in the last twenty years.

Second, studies indicate that Enlist Duo threatens the monarch butterfly, an iconic species famed for its annual migration across the continent. The monarch migration has declined sharply in recent years, driven by increasing applications of herbicides to herbicide-resistant crops, which has decimated milkweed, the sole food source for monarch caterpillars. Scientists have warned that the monarch migration is now at risk of vanishing entirely. Enlist Duo is specifically intended to kill milkweed, but so far EPA has refused to consider harm to monarch butterflies when determining whether Enlist Duo causes unreasonable environmental impacts.  Enlist Duo's effects on the monarch butterfly must be part of EPA's reanalysis.

The public deserves to know how EPA intends to address all of these concerns about the risks posed by Enlist Duo.  We ask that EPA respond promptly to the following questions:

  • What factors caused EPA to reverse its previous analysis of the health impacts of Enlist Duo and dismiss evidence linking 2,4-D to kidney abnormalities?
  • How, if at all, did EPA assess the synergistic effects of glyphosate and 2,4-D, as opposed to merely each chemical individually?
  • Does EPA have a standard practice or policy guidance for assessing the synergistic effects of chemical mixtures? If so, what is that practice, does it occur during the registration process, and did EPA follow it here?
  • Considering the World Health Organization's finding that glyphosate is a probable carcinogen, will EPA also assess the synergistic effects of the chemicals in Enlist Duo on human health - especially children's health - in addition to their effects on endangered and other plants
  • Will EPA prohibit sales of Enlist Duo while it reviews all information submitted by Dow regarding synergistic effects?
  • What is EPA's plan to evaluate Enlist Duo's harm to monarch butterflies before re-approval? Will EPA agree not to approve continued use of Enlist Duo until the agency considers and addresses the herbicide's adverse effects on monarchs?
  • What is EPA's plan to evaluate Enlist Duo's human cancer risk before re-approval? Will EPA agree not to approve continued use of Enlist Duo until the agency considers and addresses up-to-date science on glyphosate's cancer risk?
  • Will EPA agree not to re-approve Enlist Duo until the agency has completed its registration review process for glyphosate?
  • What is EPA's timeline for the review process of Enlist Duo?

Thank you for your prompt attention to these questions.  We look forward to receiving your response as soon as possible.