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U.S. Environmental Protection Agency	17-P-0278
June 21, 2017
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At a Glance
Why We Did This Review
We conducted this review to
assess the U.S. Environmental
Protection Agency's (EPA's)
management and oversight of
resistance issues related to
herbicide-resistant genetically
engineered crops. We looked
at EPA processes and
practices, steps the EPA has
taken to validate risk, and how
the agency collects herbicide
resistance data.
Approximately 90 percent of
the U.S. soybean, corn and
cotton crops are genetically
modified to withstand herbicide
applications on surrounding
weeds. However, when weeds
adapt and acquire the ability to
withstand the effects of
herbicides, this results in
herbicide resistance. According
to the EPA, the Federal
Insecticide, Fungicide, and
Rodenticide Act designates
herbicide resistance as a risk.
The EPA considers herbicide
resistance to be one of the
farmer's biggest challenges in
crop production. Substantiated
resistance must be reported to
the EPA.
This report addresses the
following EPA goal or
cross-agency strategy:
• Ensuring the safety of
chemicals and preventing
pollution.
Send all inquiries to our public
affairs office at (202) 566-2391
or visit www.epa.gov/oia.
Listing of OIG reports.
EPA Can Strengthen Its Oversight of Herbicide
Resistance With Better Management Controls
Billions of dollars in U.S. crop
value are at risk due to the
threat of herbicide-resistant
weeds. With private and public
partners, the EPA can establish
better controls to manage and
minimize the threat.
What We Found
The EPA's Office of Inspector General (OIG)
found that the agency has taken few steps
to address herbicide resistance. The EPA
believes that a delay in herbicide resistance
is in the "public good." Delaying resistance
minimizes the amount and type of herbicides
applied to combat weeds, reduces human
and environmental exposure, and increases
grower productivity. However, the EPA has several management and oversight
challenges related to the agency effectively addressing herbicide resistance.
We found that the EPA uses the pesticide registration process to collect
information on human health and environmental risks from pesticides used on
herbicide-resistant weeds, but no information is collected regarding synergism.
Synergy occurs when the effect of a mixture of chemicals is greater than the sum
of the individual effects.
In addition, labels for products such as glyphosate currently do not require
information about the chemical pathway that describes how a herbicide causes
harm to a plant (i.e., the "mechanism of action"). Not requiring this information on
labels can result in the improper use of pesticides to combat herbicide-resistant
weeds. The EPA's pesticide registration and reporting processes also do not
generate necessary herbicide resistance information for tracking, monitoring and
identifying where resistance occurs.
There is a lack of communication and collaboration between the EPA and its
public and private stakeholders regarding herbicide resistance management.
This limits the reach of actions proposed and taken by the EPA, the development
of meaningful alternatives, and the agency's ability to proactively respond to
herbicide resistance in the field. The EPA also does not have measures to track
its progress addressing and slowing the spread of herbicide resistance. With
improved management and oversight controls, the EPA can be better prepared to
assess and develop actions to address and prevent future herbicide resistance
issues.
Recommendations and Planned Agency Corrective Actions
We recommend that the Assistant Administrator for Chemical Safety and
Pollution Prevention (1) consider requiring herbicide labels include mechanisms
of action, (2) assess the need for more information on synergism, (3) improve
data collection and reporting on herbicide resistance, (4) develop performance
metrics, and (5) develop a plan for establishing consistent communication with
stakeholders. The EPA agreed with our recommendations. All recommendations
have been resolved with corrective actions pending.

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