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BOARD ON AGRICULTURE AND NATURAL RESOURCES
Genetically Engineered Crops:
Experiences and Prospects
May 11, 2016
Governing Board
Meeting

Motivation for Study
• Claims and research that extol either the benefits of or the risks
posed by current GE crops and food have created a confusing
landscape for the public and policy makers.
• A clear need for a study that carefully examined the evidence
behind these claims and the rigor of the research.
• Because the GE technologies are changing so rapidly – a need for
a study examining the cutting edge, and where that may take us
in the future.

Contextual filters that influence a person’s
perception of scientific innovations

20+ Years of Experience with
Genetically Engineered (GE) Crops
1980s
• Since the 1980s, genetic engineering has been used to
express many traits in plants
1990s
• First introduced into commercial production in mid-1990s
To
date
• For a variety of reasons, only a few GE traits are in
widespread use, mostly in maize, soybean, and cotton
• Herbicide resistance (HR) in maize, soybean, and cotton
• Insect resistance (IR) in maize and cotton
• Maize and cotton with herbicide resistance and insect
resistance

GE Crops Planted on 12% of World’s Cropland
~40% of all
GE crops
planted
in US

Committee’s Charge
• What do we know about the agronomic, environmental, health,
social, and economic effects of the crops we have experience
with?
• What are the prospects for genetic engineering in agriculture
going forward?
• What are the future opportunities and challenges emerging
genetic-engineering technologies may present, including for
regulation?

Committee on Genetically Engineered Crops
FRED GOULD (CHAIR)
North Carolina State University
RICHARD M. AMASINO
University of Wisconsin–Madison
DOMINIQUE BROSSARD
University of Wisconsin–Madison
C. ROBIN BUELL
Michigan State University
RICHARD A. DIXON
University of North Texas
JOSÉ B. FALCK-ZEPEDA
International Food Policy Research Institute (IFPRI)
MICHAEL A. GALLO
Rutgers Robert Wood Johnson Medical School (retired)
KEN GILLER
Wageningen University
LELAND GLENNA
Pennsylvania State University
TIMOTHY S. GRIFFIN
Tufts University
BRUCE R. HAMAKER
Purdue University
PETER M. KAREIVA
University of California–Los Angeles
DANIEL MAGRAW
Johns Hopkins University School of Advanced International
Studies
CAROL MALLORY-SMITH
Oregon State University
KEVIN PIXLEY
International Maize and Wheat Improvement Center (CIMMYT)
ELIZABETH P. RANSOM
University of Richmond
MICHAEL RODEMEYER
University of Virginia (formerly)
DAVID M. STELLY
Texas A&M University
C. NEAL STEWART
University of Tennessee
ROBERT J. WHITAKER
Produce Marketing Association
This study was supported by the Burroughs Wellcome Fund, the Gordon and
Betty Moore Foundation, the New Venture Fund, the U.S. Department of
Agriculture, and the National Academy of Sciences.

Committee’s Process
• NRC report 1996---Understanding Risk: Informing Decisions in
a Democratic Society. A purely technical assessment of risk
could result in an analysis that accurately answered the wrong
questions and will be of little use to decision makers.
• Academy study process “efforts are made to solicit input from
individuals who have been directly involved in, or who have
special knowledge of, the problem under consideration”
• Academy study process “Report should show that the
committee has considered all credible views on the topics it
addresses.”

Committee’s Process
• Examined the relevant literature (1000+ research
and other publications)
• Held information-gathering meetings
– 3 meetings + 15 webinars = 80 presentations
– All presentations are archived on the study’s
website
• Read more than 700 comments submitted by
members of the public

Committee’s Process:
Information-Gathering Meetings
• Social science research on GE
crops
• Intellectual property issues
• GE quality traits
• Socioeconomic issues in
developing and developed
countries
• Safety of foods derived from GE
crops
• U.S. regulatory system
• Observations by U.S. agricultural
extension specialists
• RNA interference
• Microbiome
• Perspectives on donor
organizations working on
international agricultural
development
• GE trees
• International trade
• Conventional plant breeding
• Genetic engineering for disease
resistance

Speakers covered
wide range of topics

13
 Dedicated website and
listserv; study FAQs,
 Broad outreach for
nominations, input
 1100 subscribers at
study start, 1800 now
 2-min Statement of
Task video; meet the
members videos
 1200 Twitter followers
 Workshop-like public
meetings and webinars
with webcast
 80 speakers
 Topical understandable
products
Broad Communications Throughout Study

A Key Message:
No Longer Clear Distinction Between
Crop-Improvement Approaches
• New technologies in genetic engineering and
conventional breeding are blurring the distinction
between the two approaches
• Synergy from combined use of GE and CB
• All technologies for improving plant genetics have
the potential to change foods in ways that raise
safety issues

Definitions
• Genetic Engineering =
• Conventional Breeding =

Genetic Engineering Processes are Changing
Yesterday’s Approaches
• Genetic change introduced with
soil bacterium, Agrobacterium
tumefaciens
• Genetic change introduced with
gene gun
Today and Tomorrow’s Approaches
• Genes added or deleted with
genome-editing techniques (such
as CRISPR/Cas9) –untraceable
• Plant and pest gene expression
silenced with RNA interference
• Creation and insertion of synthetic
chromosomes

Committee’s Analysis of Current GE Crops
• Based on experience to date
– Mostly restricted to herbicide resistant and insect resistant
varieties of maize, cotton, and soybean
– Data from industrial scale and low resource farms
• Analysis conducted for:
– Agronomic and environmental effects
– Human health effects
– Social and economic effects

Agronomic and Environmental Effects:
Insect Resistance
in Maize, Cotton, and Soybean
Insect Resistance in Maize, Cotton, and Soybean
• Reduced the gap between actual yield and potential yield under circumstances
where targeted insect pests caused substantial damage to non-GE varieties and
synthetic chemicals could not provide practical control.
• In areas of the United States and China where adoption of either Bt maize or Bt
cotton is high, some insect-pest populations are reduced regionally, benefiting
both adopters and nonadopters of Bt crops.
• Planting Bt crops tended to result in higher insect biodiversity than planting similar
varieties without the Bt trait and using synthetic insecticides.
• Application of synthetic insecticides to Bt maize and cotton has decreased, and in
some cases, the use of Bt crops has been associated with lower use of insecticides
in non-Bt varieties of the crop and other crops.
• Target insects have been slow to evolve resistance to Bt proteins when crops
produced a high dose of Bt protein and there were refuges where susceptible
insects survived. Where resistance-management strategies were not followed,
damaging levels of resistance evolved in some target insects.

Rates of insecticide application by adopters and nonadopters of
Bt maize in the United States from 2001 to 2010. SOURCE:
Fernandez-Cornejo et al. (2014).

Agronomic and Environmental Effects:
Herbicide Resistance
in Maize, Cotton, and Soybean
Herbicide Resistance in Maize, Cotton, and Soybean
• Herbicide resistance contributes to higher yield where weed control is improved
because of the effectiveness of the specific herbicide used in conjunction with the
herbicide-resistant crop.
• Total kilograms of herbicide applied per hectare of crop per year initially declined,
but these decreases have not generally been sustained. However, total kilograms
of herbicide applied per hectare is an uninformative metric for assessing changes
in risks to the environment or to human health due to GE crops because of the
hazards posed by different herbicides.
• Weed species less susceptible to glyphosate may increase in a HR crop system
using glyphosate. However, there is little evidence that agronomic harm has
resulted.
• In many locations, some weeds had evolved resistance to glyphosate. Integrated
weed-management approaches can be used to delay resistance, especially in
cropping systems not yet exposed to continuous glyphosate applications. Further
research on weed resistance management is needed.

Herbicide use in cotton, maize, and soybeans in the United
States, 1995–2010. SOURCE: Fernandez-Cornejo et al. (2014).

Experiences:
Agronomic and Environmental Effects
General Findings:
• Diversity in the crops grown in the United States has decreased
since 1987, but no link could be established between this pattern
and GE crops.
• Although gene flow has occurred, no examples have demonstrated
an adverse environmental effect of gene flow from a GE crop to a
wild, related plant species.
• No conclusive evidence of cause-and-effect relationships between
GE crops and environmental problems.
• No evidence from USDA data that genetic engineering has
increased the rate at which U.S. crop yields are increasing.

SOURCE:
Duke (2015).
CottonYieldMaizeYieldSoybeanYield
USDA Data

Experiences:
Human Health Effects
The committee re-examined most of the original studies:
• Studies conducted with animals.
• Long-term data on the health and feed conversion efficiency of livestock
before and after the introduction of GE crops to livestock diets.
• Comparative data on nutrient and chemical composition between GE
crops and non-GE counterparts.
• Epidemiological data of specific health problems for populations in the
United States and Canada, where GE foods have been consumed for
many years, and populations in the United Kingdom and western
Europe, where GE foods are not widely consumed.
No Persuasive Evidence of Adverse Health Effects Directly
Attributable to Consumption of Foods Derived from GE Crops

Nonregressive tumors in rats fed genetically engineered (GE)
maize treated or not treated with Roundup and those fed non-
GE maize and water treated with Roundup.
SOURCE:
Séralini et al. (2014).
Over 3 pages
of report

Experiences:
Social and Economic Effects
CONCLUSION: Available evidence generally indicates positive
economic outcomes for producers of GE maize, cotton, and
soybean, although there is high heterogeneity.
CAVEATS:
• Utility of the GE crop depends on the usefulness of the trait and the
genetics of the crop to the specific farm environment.
• Although GE crops have provided economic benefits to many small-scale
farmers in the early years of adoption, enduring and widespread gains will
depend on institutional support, and access to profitable local and global
markets.

Experiences:
Social and Economic Effects
• Regulation has to balance biosafety and consumer confidence with the
potential to slow innovation and deployment of beneficial products.
• Patents may limit access by farmers, markets, and plant breeder who lack
resources to pay licensing fees or mount legal challenges, but this also applies
to non-GE crops.
• GE crops, like other technological advances in agriculture, are not able by
themselves to address fully the complex challenges to productivity on small-
scale farms in food insecure places.
– Other issues such as soil fertility, integrated pest management, and storage need to be
addressed to improve crop productivity, decrease post-harvest losses, and increase food
security.
Benefits to Intended Stakeholders Depend on the Social and
Economic Contexts in which Technology is Developed and Diffused

Prospects for Genetic Engineering
CONCLUSION: Emerging genetic-engineering technologies are
expected to increase the precision, complexity, and diversity in GE
crop development.
• Resistance traits for a broader array of insect pests and diseases
in more crops are likely.
• Other possible new traits, such as increased efficiency in
photosynthesis and nitrogen use, may increase yield potential,
but it is too early to know if such complex traits will be
successfully deployed.
• Balanced public investment in diverse GE and Non-GE
approaches is recommended to address food security

Prospects for Genetic Engineering:
Evaluation with -Omics Technologies
-Omics Technologies
• -Omics technologies can be used to examine plant DNA
sequences, RNA expression, and molecular composition.
• Such technologies could be used to examine new crop
varieties for intended and unintended effects (whether
genetically engineered or conventionally bred), but they
require further development.
• To realize their potential to assess intended and unintended
effects of new crop varieties and to improve the production
and quality of crop plants, a more comprehensive knowledge
base of plant DNA, RNA, protein, and metabolites should be
constructed for the range of variation inherent in both
conventionally bred and genetically engineered crop species.

Diverse Regulatory Approaches
• It is not surprising to find a diversity of regulatory processes for
products of genetic engineering because they mirror the broader
social, political, legal and cultural differences among countries. All
issues cannot be answered by technical assessments alone.
• Disagreements among countries about regulatory models and
resulting trade disagreements are expected to continue as part of
the international landscape.
• Committee examined approaches in US, Brazil, EU, and Canada

Regulation Should Be Based on Novelty
• In determining whether a new plant variety should be
subject to a premarket approval for safety, regulators
should focus on:
 the extent to which the novel characteristics of the plant variety (both
intended and unintended characteristics) are likely to pose a risk to
human health or the environment
 the extent of uncertainty about the severity of potential harm, and
the potential for human exposure – regardless of whether the plant
was developed using GE or conventional-breeding processes.
• So-called -omics technologies will be critical in enabling
these regulatory approaches.

Report to be Released
Tuesday, May 17
• 11am Eastern at
Keck Center
• Live Webcast
• Webcast will be
recorded and
archived

Acknowledgments
Academies Staff
Sponsors
Committee
Reviewers
Speakers
Members of the public who
took the time to provide
comment

Thank you!
Visit nas-sites.org/ge-crops next week
to find
• The report for free PDF download
• Report in Brief (4-page lay summary)
• Briefing slides and archived public
release webcast
Questions?
• Contact gecrops@nas.edu
Join the conversation:
#GECropStudy

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