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Registration of Enlist Duo

Enlist Duo, an herbicide product containing 2,4-D and glyphosate, was first registered in 2014 for use on genetically engineered (GE) corn and soybean crops in 6 states, and later in an additional 9 states. At this time, EPA is amending the registration to allow use on GE cotton in those 15 states and extend the use of Enlist Duo on GE corn, soybean and cotton to an additional 19 states.

EPA’s decision to amend the registration for Enlist Duo to include GE cotton crops and to extend its use on all three crops to 19 additional states is described in the final registration decision document that can be found at EPA docket # EPA‑HQ‑OPP‑2016‑0594 at www.regulations.gov

Learn more about Enlist Duo and EPA's registration decision:

  1. What is Enlist Duo?
  2. What decision is EPA making about Enlist Duo and why is EPA taking this action?
  3. Is Enlist Duo safe?
  4. How did EPA assess the safety of Enlist Duo?
  5. What safety precautions are in place for the use of Enlist Duo?
  6. Did EPA take into account the 10X safety factor specified under the Food Quality Protection Act to protect children?
  7. What about the registrant’s claims of synergism and the court-ordered remand?
  8. How is EPA addressing the issue of herbicide-resistant weeds?
  9. Is 2,4-D the same as “Agent Orange”?
  10. How does EPA’s work relate to what USDA/APHIS is doing in this area?
  11. How will Enlist Duo affect pollinators/bees?
  12. Enlist Duo is registered for use in what states?

1. What is Enlist Duo?

Enlist Duo is a combination product of two previously registered herbicides:

Enlist Duo contains a variation of 2,4-D – the choline salt of 2,4-D – that is less prone to drift and volatilization than its other forms. Enlist Duo has unique and protective labeling requirements which will help prevent off field movement of this product and robust methods for helping to manage the issue of herbicide resistant weeds.

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2. What decision is EPA making about Enlist Duo and why is EPA taking this action?

Enlist Duo was first registered in 2014 for use in genetically engineered (GE) corn and soybean crops in 6 states, and later in an additional 9 states. After completing a rigorous analysis of all the scientific studies, EPA is amending the registration of Enlist Duo to include use on GE cotton in the existing 15 states and to extend the use of Enlist Duo for GE cotton, corn and soybean crops to an additional 19 states. A list of the states where Enlist Duo has been approved is presented below.  

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3. Is Enlist Duo safe?

When used according to label directions, Enlist Duo is safe for everyone, including infants, the developing fetus, the elderly and more highly exposed groups such as agricultural workers. It also meets the safety standard for the environment, including endangered species. We assessed risks from the 2,4-D choline salt to endangered species and found that there would be no effect on listed species from this active ingredient in the approved use areas when the product is used according to label directions. The decision to register Enlist Duo for use on GE cotton, corn and soybean meets the rigorous Food Quality Protection Act standard.

Glyphosate is already registered for these uses and did not undergo further review as part of the assessment for this product.

EPA's decision to modify the registration of Enlist Duo meets both the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and the Federal Food, Drug, and Cosmetic Act (FFDCA) safety standards.

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4. How did EPA assess the safety of Enlist Duo?

With Enlist Duo's large body of scientific information, EPA: 

  • Evaluated risks to all age groups, from infants to the elderly, as well as agricultural workers.
  • Used worst-case estimates for exposures from pesticide drift or movement, food, drinking water and use around homes and public spaces. (Example: We assumed that all cotton, corn and soybeans in the United States would be treated with Enlist Duo, certainly a gross exaggeration.)
  • Aggregated risks, looking at total potential exposure from all these sources.
  • Used conservative estimates for impacts on the environment, including risks to endangered species.

Glyphosate is already registered for these uses and did not undergo further review as part of the assessment for this product.

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5. What safety precautions are in place for the use of Enlist Duo?

Our human health risk assessment showed very low risks to human health, resulting in a determination that the pesticide's use, as approved, will cause no health risks to people living near treated fields, even at the edge of those fields. Even so, we added protective measures to ensure there is reduced off-field movement of the pesticide: 

  • The Agency's approval pertains only to the low-volatility pesticide formulation.
  • The pesticide may not be applied from aircraft.
  • It may not be applied when wind speed is over 15 mph.
  • Only approved nozzles at specified pressures may be used for application.
  • A 30-foot, within-field buffer has been set to protect sensitive areas when the wind is blowing toward them. This will also further protect bystanders and non-target plants.

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6. Did EPA take into account the 10X safety factor specified under the Food Quality Protection Act to protect children?

The 10X FQPA safety factor is designed to account for potential pre- and post-natal toxicity and completeness of the data with respect to exposure and toxicity to infants and children, but may be reduced based upon reliable data. In this case, the dataset is complete and very robust, and the 10X was reduced to 1X based on reliable data. Although the Agency believes its decision to reduce the FQPA safety factor to 1X is scientifically sound and consistent with established science policy, in order to more fully characterize risk potential, we also assessed risks retaining the 10X FQPA safety factor. Using 10X, risks were still acceptable for all age groups for all components of the assessment: dietary food and drinking water exposure, volatility, spray drift, residential, and aggregate assessment.

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7. What about the registrant's claims of synergism and the court-ordered remand?

Enlist Duo, which contains the choline salt of 2,4-D and glyphosate was first registered in 2014 for use on genetically engineered (GE) corn and soybean crops in 6 states. The data submitted in support of the registration for the two chemicals individually as well as information on the two chemicals together in this specific formulation showed no indication of synergism for mammals, freshwater fish and freshwater invertebrates, and the Agency therefore believed it reasonable to assume there are no synergistic interactions for non-target plants. In addition, the mixture of the two ingredients did not show greater toxicity to mammals compared to either compound alone. 

After granting the registration and an amendment to allow use in an additional 9 states, however, the Agency discovered that the registrant had made claims of synergy between the ingredients in the herbicide’s formula in patent applications to the U.S. Patent and Trademark Office that had not been shared with EPA at the time of registration. As the registration was being litigated when EPA discovered the patent application claims of synergy, the Agency requested that the court remand the registration to EPA, which the court did in January 2016, thus bringing that litigation to an end. EPA then requested and received additional formulation-specific data from the registrant that would address any uncertainty in the risk assessments due to the “synergistic effects” claims made in patent applications for the two constituent herbicides and confirm whether the original buffers were still appropriate. 

After reviewing the additional data submitted by the registrant, EPA has determined that the information supports the original decision. These data demonstrate that the combination of 2,4-D choline and glyphosate in Enlist Duo does not show any increased toxicity to plants and is therefore not of concern. 

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8. How is EPA addressing the issue of herbicide-resistant weeds?

We are concerned about the possibility that using Enlist Duo could result in the spread of weeds resistant to 2,4-D. Therefore, we are requiring special measures to address this concern. The terms of the registration impose requirements on the manufacturer including: 

  • reporting to EPA;
  • grower education; and
  • remediation programs.

In addition:

  • The registration expires in five years, allowing EPA to revisit the issue of resistance.
  • The label also contains information on resistance management consistent with the Weed Science Society of America’s Best Management Practices (BMPs) for comprehensive resistance management approaches. 

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9. Is 2,4-D the same as "Agent Orange"? 

No. “Agent Orange” was a mixture of two different herbicides, 2,4,5-T and 2,4-D, as well as kerosene and diesel fuel. Agent Orange contained high levels of dioxin, a contaminant found in 2,4,5-T that causes cancer and other health concerns in people. EPA canceled all use of 2,4,5-T in 1985 because of these risks. 

In evaluating this request to expand the use of Enlist Duo, we performed a thorough and conservative safety review for any potential human health and environmental risks associated with the expanded use of 2,4-D on these GE plants and also explicitly considered any possible risks from any formulation contaminants.

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10. How does EPA's work relate to what USDA/APHIS is doing in this area?

The U.S. Department of Agriculture (USDA) is responsible for determining whether to allow the sale of seeds that have been genetically engineered. EPA regulates the pesticide used on those seeds or crops under the Federal Insecticide, Fungicide, and Rodenticide Act and the pesticide residues remaining in or on food from those uses under the Federal Food, Drug, and Cosmetic Act. 

The two agencies worked closely to ensure a thorough scientific review of the potential impacts on human health and the environment associated with the uses and have shared information and assessments to inform both agencies’ respective regulatory decisions. 

On September 17, 2014, the USDA announced its final decision to allow the sale of seeds that have been genetically engineered to tolerate 2,4-D and glyphosate.

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11. How will Enlist Duo affect pollinators/bees?

Conservative, screening-level risk assessments have determined that the 2,4-D choline salt is practically non-toxic to bees. Therefore, we expect there will be no adverse impacts to pollinators/bees. Regardless, we are working aggressively to protect bees and other pollinators from the potential effects of pesticides and are engaged in national and international efforts to address those concerns. We are working with beekeepers, growers, pesticide manufacturers, the USDA and states to apply technologies to reduce pesticide exposure to bees, advance best management practices, enhance enforcement guidance and ensure that real-world pollinator risks are accounted for in our pesticide regulatory decisions. 

Learn more about Protecting Bees and Other Pollinators from Pesticides.

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12. Enlist Duo is registered for use in what states?

Enlist Duo was previously registered for use on GE corn and soybean crops in: 

  • Arkansas,
  • Illinois,
  • Indiana,
  • Iowa,
  • Kansas,
  • Louisiana,
  • Minnesota,
  • Mississippi,
  • Missouri,
  • Nebraska,
  • North Dakota,
  • Oklahoma,
  • Ohio,
  • South Dakota, and
  • Wisconsin.

The final decision to expand the use of Enlist Duo will allow use on GE cotton in the above mentioned states and will expand the use on GE corn, soybean and cotton crops to include: 

  • Alabama,
  • Arizona,
  • Colorado,
  • Delaware,
  • Florida,
  • Georgia,
  • Kentucky,
  • Maryland,
  • Michigan,
  • North Carolina,
  • New Jersey,
  • New Mexico,
  • New York,
  • Pennsylvania,
  • South Carolina,
  • Tennessee,
  • Texas,
  • Virginia, and
  • West Virginia.

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