Genetically Engineered Crops Experiences and Prospects (2016) / Chapter Skim
Currently Skimming:
Summary
Summary
Pages 5-28
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 5... ...
For a variety of scientific, economic, social, and regulatory reasons, most genetically engineered (GE) traits and crop varieties that have been developed are not in commercial production.
|
From page 6... ...
Over 70 million hectares were planted in the United States. GE crops produced in Brazil, Argentina, India, and Canada accounted for over 90 million hectares.
|
From page 7... ...
Those approaches and examples of how they may be used in the future to change traits in agricultural crops are described in Chapters 7 and 8, and the committee's findings and conclusions are in the "Prospects for Genetic Engineering" section of this summary. The committee conducted its work at a time during which the geneticengineering approaches that had been in use when national and regional regulatory systems were first developed were being replaced with newer approaches that did not fit easily into most regulatory systems or even into some older definitions of the term genetically engineered.
|
From page 8... ...
The study will: • Examine the history of the development and introduction of GE crops in the United States and internationally, including GE crops that were not commer cialized, and the experiences of developers and producers of GE crops in different countries. • Assess the evidence for purported negative effects of GE crops and their ac companying technologies, such as poor yields, deleterious effects on human and animal health, increased use of pesticides and herbicides, the creation of "super-weeds," reduced genetic diversity, fewer seed choices for producers, and negative impacts on farmers in developing countries and on producers of non-GE crops, and others, as appropriate.
|
From page 9... ...
First, genetic engineering has had and continues to have the potential to introduce many traits into agricultural crops; however, only two traits -- insect resistance and herbicide resistance -- have been used widely. Claims about the effects of existing GE crops frequently assume that the effects of those two traits apply to potential effects of the geneticengineering process generally; however, different traits probably have different effects.
|
From page 10... ...
Washington, DC: National Academies Press. 3 For more information about the National Academies study process, see http://www. nationalacademies.org/studyprocess/.
|
From page 11... ...
Agronomic and Environmental Effects The committee examined the effects of GE insect resistance on crop yield, insecticide use, secondary insect-pest populations, and the evolution of resistance to the GE trait in targeted insect populations. It looked at the effects of GE herbicide resistance on crop yield, herbicide use, weed-species distribution, and the evolution of resistance to the GE trait in targeted weed species.
|
From page 12... ...
Limitations of natural nutrient and water availability cause gaps between the potential yield and actual yield if nutrient supplementation and water supplementation are not possible. Actual yield may be further curtailed by "reducing factors": insect pests and diseases, which physically damage crops; weeds, which reduce crop growth by competition for water, light, and nutrients; and toxicity caused by waterlogging, soil acidity, or soil contamination.
|
From page 13... ...
The herbicide is applied to a field with a herbicide-resistant crop to control weeds susceptible to that herbicide. Studies of GE herbicide-resistant crops indicate that 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.
|
From page 14... ...
There is disagreement among researchers about how much GE traits can increase yields compared with conventional breeding. In addition to assessing detailed surveys and experiments comparing GE with non-GE crop yields, the committee examined changes over time in overall yield per hectare of maize, soybean, and cotton reported by the U.S.
|
From page 15... ...
• In future experimental survey studies that compare crop varieties with Bt traits and those varieties without the traits, it is important to assess how much of the difference in yield is due to decreased insect damage and how much may be due to other biological or social factors. • Given the theoretical and empirical evidence supporting the use of the high dose/refuge strategy for Bt crops to delay the evolution of resistance, development of crop varieties without a high dose of one or more toxins should be discouraged and planting of appro priate refuges should be incentivized.
|
From page 16... ...
It then looked for evidence supporting or refuting claims related to specific health effects. The committee makes clear in its report that there are limits to what can be known about the health effects of any food, whether it is produced through conventional breeding alone or in conjunction with genetic engineering.
|
From page 17... ...
The committee received a number of comments from people concerned that GE food consumption may lead to higher incidence of specific health problems including cancer, obesity, gastrointestinal tract illnesses, kidney disease, and such disorders as autism spectrum and allergies. There have been similar hypotheses about long-term relationships between those health
|
From page 18... ...
With regard to the gastrointestinal tract, the committee determined, on the basis of available evidence, that the small perturbations sometimes found in the gut microbiota of animals fed foods derived from GE crops are not expected to cause health problems. Understanding of this subject is likely to improve as the methods for identifying and quantifying gut microorganisms mature.
|
From page 19... ...
Analyses to determine the health risk posed by glyphosate and formulations that include it must take marginal exposure into account. On the basis of its detailed examination of comparisons between currently commercialized GE and non-GE foods in compositional analysis, acute and chronic animal-toxicity tests, long-term data on health of livestock fed GE foods, and epidemiological data, the committee concluded that no differences have been found that implicate a higher risk to human health safety from these GE foods than from their non-GE counterparts.
|
From page 20... ...
GE plants with insect, virus, and fungus resistance and with drought tolerance were in development and could be useful to small-scale farmers if they are deployed in appropriate crops and varieties. Evidence shows that GE crops with insect resistance and herbicide resistance differentially affect men and women, depending on the gendered division of labor for a specific crop and for particular localities.
|
From page 21... ...
In the case of GE crops, adventitious presence is the unintended and accidental presence of low levels of GE traits in seeds, grains, or foods. Preventing adventitious presence is valuable for societal reasons because farmers want the freedom to decide what crops to grow on the basis of their skills, resources, and market opportunities and for economic reasons because markets are differentiated and organic and nonorganic, non-GE crops command a price premium.
|
From page 22... ...
GE crops, like other technological advances in agriculture, are not able by themselves to address fully the wide variety of complex challenges that face smallholders. Such issues as soil fertility, integrated pest management, market development, storage, and extension services will all need to be addressed to improve crop productivity, decrease postharvest losses, and increase food security.
|
From page 23... ...
That is true for conventional breeding and for breeding that includes genetic engineering. The rapid progress of genome-editing tools, such as CRISPR/Cas9, should be able to complement and extend contemporary methods of genetic improvement by increasing the precision with which GE changes are made in the plant genome.
|
From page 24... ...
More progress in crop improvement could be made by using conventional breeding and genetic engineering jointly rather than in isolation. The emerging technologies are expected to result in increased precision, complexity, and diversity in GE crop development.
|
From page 25... ...
• Balanced public investment in these emerging genetic-engineering technologies and in a variety of other approaches should be made because it will be critical for decreasing the risk of global and local food shortages. REGULATION OF CURRENT AND FUTURE GENETICALLY ENGINEERED CROPS Risk analyses and assessments of GE crops offer technical support for regulatory decision-making but also establish and maintain the legitimacy of government regulatory authorities.
|
From page 26... ...
Emerging genetic-engineering technologies challenge most existing regulatory systems by blurring the distinction between genetic engineering and conventional plant breeding while enabling increasingly profound alterations of plant metabolism, composition, and ecology. As pointed out in previous National Research Council reports, it is the product, not the process, that should be regulated.
|
From page 27... ...
In Tier 1, there are no differences between the variety under consideration and a set of conventionally bred varieties that represent the range of genetic and phenotypic diversity in the species. In Tier 2, differences that are well understood to have no expected adverse health effects are detected.
|
From page 28... ...
The committee offers that final recommendation because the processbased approach has become less and less technically defensible as the old approaches to genetic engineering become less novel and the emerging processes fail to fit old categories of genetic engineering. Moreover, because the emerging technologies have the potential to make both incremental changes that lack substantial risk and major changes that could be problematic, the committee recommends that a tiered approach to regulation should be developed that uses trait novelty, potential hazard, and exposure as criteria.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.