Registration of Enlist Duo

EPA is registering Enlist Duo, an herbicide product that combines two previously approved herbicides:

2,4-D and glyphosate are two of the most widely used herbicides in the world to control weeds. Dozens of countries including the United States, Canada, Mexico, Japan and 26 European Union Members have approved these pesticides for use on numerous crops and residential lawns. Last year, Canada approved the use of Enlist Duo for the same uses that EPA is authorizing.

The pesticide will be used to control weeds in corn and soybeans genetically engineered (GE) to tolerate 2,4-D and glyphosate. The Agency’s decision is protective of all, including the developing fetus, infants and children, the elderly and farmworkers.

The final regulatory decision document is available in EPA docket EPA-HQ-OPP-2014-0195 at www.regulations.gov. EPA is accepting comments until December 15, 2014 (an additional 30 days from the original deadline) on whether to register Enlist Duo in ten additional states.

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. How does EPA's final regulatory decision address the issues of herbicide-resistant weeds?
  4. Is Enlist Duo safe?
  5. How did EPA assess the safety of Enlist Duo?
  6. What safety precautions is EPA putting in place for the use of Enlist Duo?
  7. Will this action substantially increase the use of 2,4-D and glyphosate? Is this true and why would you allow that?
  8. Is 2,4-D the same as “Agent Orange”?
  9. How does EPA’s work relate to what USDA/APHIS is doing in this area?
  10. How will Enlist Duo affect pollinators/bees?
  11. Did EPA take into account the 10X safety factor specified under the Food Quality Protection Act to protect children?
  12. Why is EPA only registering Enlist Duo for use in six states?

1. What is Enlist Duo?

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

2,4-D and glyphosate are two of the most widely used herbicides in the world to control weeds. Dozens of countries including the United States, Canada, Mexico, Japan and 26 European Union members have approved these pesticides for use on numerous crops and residential lawns. Last year, Canada approved the use of Enlist Duo for the same uses that EPA is authorizing.

One difference is that Enlist Duo contains a variation (the choline salt) of 2,4-D that is less prone to drift and volatilization than its other forms.

Glyphosate is already registered for use on genetically engineered corn and soybeans. 2,4-D is registered for use on corn and soybeans.

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

After completing a rigorous analysis of all the scientific studies and considering all public comments, EPA is registering the herbicide Enlist Duo to control weeds for genetically engineered corn and soybeans.

This product will provide a new tool to help farmers manage weeds that have become resistant to herbicides.

We received applications from Dow AgroSciences requesting the use of a new, lower volatility pesticide formulation using the choline salt of 2,4-D and glyphosate on genetically engineered (GE) corn and soybeans. Concurrent with the EPA regulatory process, the U.S. Department of Agriculture received applications from Dow AgroSciences to introduce into the U.S. market GE corn and soybeans that would tolerate exposure to 2,4 D. USDA announced its approval of these GE crops on September 17, 2014. These GE corn and soybean plants are the first developed to be resistant to 2,4-D and are intended to allow farmers to use Enlist Duo to control the weeds that have developed resistance to glyphosate.

Weeds are becoming increasingly resistant to glyphosate-based herbicides and are posing a serious problem for farmers. This action will provide an additional tool to reduce the spread of glyphosate-resistant weeds. We are requiring a stewardship plan to ensure that use of Enlist Duo successfully manages weed resistance problems.

See question 3 for more on how EPA is addressing herbicide resistance.

See Registration Documents for Enlist Duo Herbicide.

3. How does EPA’s final regulatory decision address the issues 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 also proposing special requirements to address this concern. The terms of the registration impose requirements on the manufacturer including:

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

In addition:

  • The registration will expire in six years, allowing EPA to revisit the issue of resistance.
    • ​In the future, the Agency intends to apply this approach to weed resistance management for all existing and new herbicides used on herbicide-tolerant crops.
  • The label will also contain information on resistance management consistent with the Weed Science Society of America’s Best Management Practices (BMPs) for comprehensive resistance management approaches.

4. 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.

Use of Enlist Duo is safe for the environment, including endangered species. The Agency 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 area when the product is used according to label directions. 

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 register Enlist Duo meets the rigorous Food Quality Protection Act standard of "reasonable certainty of no harm" to human health.

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5. 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 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 worst-case estimates for impacts on the environment, including risks to endangered species.

6. What safety precautions is EPA putting in place for the use of Enlist Duo?

Our human health risk assessment for this registration decision included extensive analysis of the potential for risks to people living near treated agricultural fields, including children and adults, from sources such as volatilization and spray drift. 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.
  • A 30-foot, within-field buffer has been set to protect endangered plants and will also further protect bystanders and non-target plants.

7. Will this action substantially increase the use of 2,4-D and glyphosate? Is this true and why would you allow that?

We expect this new product will replace some of the current use of glyphosate, which has been increasing in recent years due to the development of weeds it no longer kills. 2,4-D will be effective in killing these weeds, which should help reduce the use of glyphosate.

2,4-D is currently registered for both corn and soybeans in the United States. EPA understands that as farmers start using Enlist Duo, there will be an increase in the use of the choline salt of 2,4-D. EPA used a conservative risk assessment to evaluate a possible increase in the use of the choline salt of 2,4-D. For exposure estimates, agency scientists assumed that 100% of the corn and soybeans in the United States would be treated – a worst-case scenario – and for glyphosate, these use patterns are already on registered products. The annual application rate of glyphosate for corn and soybeans remains unchanged. Whereas the annual application rates of 2,4-D are not changed for corn, additional applications would be allowed for soybeans. This could result in an increase in the total amount applied annually to soybeans if growers elect to apply the additional applications as allowed by the label.

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8. 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 requested use, 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.

9. 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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10. 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.

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

The 10X FQPA safety factor must be applied in cases where EPA does not have a complete data set. 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.  

12. Why is EPA only registering Enlist Duo for use in six states?

The initial group of six states – Illinois, Indiana, Iowa, Ohio, South Dakota and Wisconsin – were part of the Agency’s original proposed registration for the Enlist Duo product. During the decision-making process, EPA scientists completed an endangered species risk assessment for the 2,4-D choline salt, as required by the Endangered Species Act, for these initial six states and concluded that the use, as approved would not pose a risk to endangered species or their habitat. 

EPA scientists have now completed risk assessments for the 2,4-D choline salt for ten additional states. The Agency is accepting comments until December 15, 2014 (an additional 30 days from the original due date) on whether to register Enlist Duo in those ten additional states. The states are:

  • Arkansas.
  • Kansas. 
  • Louisiana.
  • Minnesota.
  • Mississippi. 
  • Missouri.
  • Nebraska.
  • Oklahoma.
  • Tennessee.
  • North Dakota.

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