Download Risks of Genetic Engineering

HISTORY OF GENETIC ENGINEERING
Before genetic engineering:
Prehistoric times to 1900
Gatherers find food from plants they find in nature, and farmers plant seeds saved from domesticated crops. Foods are
manipulated through the use of yeast and fermentation. Some naturalists and farmers begin to recognize "hybrids," plants
produced through natural breeding between related varieties of plants.
1900
European plant scientists begin using Gregor Mendel's genetic theory to manipulate and improve plant species. This is
called "classic selection." A plant of one variety is crossed with a related plant to produce desired characteristics.
Modern genetic engineering
1953
James Watson and Francis Crick publish their discovery of the three-dimensional double helix structure of DNA. This
discovery will eventually lead to the ability of scientists to identify and "splice" genes from one kind of organism into the
DNA of another.
1973
Herbert Boyer and Stanley Cohen combine their research to create the first successful recombinant DNA organism.
1980
The U.S. Supreme Court in Diamond v. Chakrabarty rules that genetically altered life forms can be patented. The decision
allows the Exxon Oil Company to patent an oil-eating microorganism.
1982
The U.S. Food and Drug Administration approves the first genetically engineered drug, Genentech's Humulin, a form of
human insulin produced by bacteria. This is the first consumer product developed through modern bioengineering.
1986
The first field tests of genetically engineered plants (tobacco) are conducted in Belgium.
1987
The first field tests of genetically engineered crops (tobacco and tomato) are conducted in the United States.
1992
Calgene's Favr Savr tomato, engineered to remain firm for a longer period of time, is approved for commercial production
by the US Department of Agriculture.
1992
The FDA declares that genetically engineered foods are "not inherently dangerous" and do not require special regulation.
1994
The European Union's first genetically engineered crop, tobacco, is approved in France.
2000
International Biosafety Protocol is approved by 130 countries at the Convention on Biological Diversity in Montréal,
Canada. The protocol agrees upon labeling of genetically engineered crops, but still needs to be ratified by 50 nations
before it goes into effect.
What Is Genetic Engineering?
Genetic engineering refers to a set of technologies that are being used to change the genetic makeup of cells and
move genes across species boundaries to produce novel organisms. The techniques involve highly sophisticated
manipulations of genetic material and other biologically important chemicals.
Genes are the chemical blueprints that determine an organism's traits. Moving genes from one organism to
another transfers those traits. Through genetic engineering, organisms are given new combinations of genes—
and therefore new combinations of traits—that do not occur in nature and, indeed, cannot be developed by
natural means. Such an artificial technology is radically different from traditional plant and animal breeding.
Novel organisms
Nature can produce organisms with new gene combinations through sexual reproduction. A brown cow bred to
a yellow cow may produce a calf of a completely new color. But reproductive mechanisms limit the number of
new combinations. Cows must breed with other cows (or very near relatives). A breeder who wants a purple
cow would be able to breed toward one only if the necessary purple genes were available somewhere in a cow
or a near relative to cows. A genetic engineer has no such restriction. If purple genes are available anywhere in
nature—in a sea urchin or an iris—those genes could be used in attempts to produce purple cows. This
unprecedented ability to shuffle genes means that genetic engineers can concoct gene combinations that would
never be found in nature.
New risks
Contrary to the arguments made by some proponents, genetic engineering is far from being a minor extension of
existing breeding technologies. It is a radically new technology for altering the traits of living organisms by
inserting genetic material that has been manipulated by artificial means. Because of this, genetic engineering
may one day encompass the routine addition of novel genes that have been wholly synthesized in the laboratory.
Novel organisms bring novel risks, however, as well as the desired benefits. These risks must be carefully
assessed to make sure that all effects—both desired and unintended—are benign. UCS advocates caution,
examination of alternatives, and careful case-by-case evaluation of genetic enginering applications within an
overall framework that seeks to move agricultural systems of food production toward sustainability.
Genetic Engineering
Genetic engineering is a process that involves the modification of different traits in organisms by use of a
technology known as recombinant DNA (rDNA) technology. This process has caused different reactions from
the experts in genetics and the public at large, with some thinking that it is a breakthrough in Biology, and
others thinking that it is against the natural set up of things. That aside, there has been progressive studies on
the same- a factor that was not possible in the past because of the complex nature of the DNA and its
components.
Some of the advantages of genetic engineering include the prevention of disease. With genetics, it is easier for
the experts to figure out the plants, people and animals that are prone to hereditary diseases and then prepare
them for the inevitable or prevent them from occurring. It has also made it possible for infectious diseases from
being spread. The genes that have the code for the anti-viral proteins for the antigens will be implanted in the
organism, and thus deal with the disease.
With genetic engineering, the genes can also be manipulated to enable people display desirable characteristics.
One example of this is the creation of the Enviropig. Pigs produce manure that is high in phytate, a version of
phosphorus, and when farmers use it on their farms, the chemicals are washed into the watershed where they
lead to the creation of algae blooms that will take up oxygen in the water as well as kill marine life. Through
genetic engineering, the scientists have stopped this by adding E.coli bacteria and DNA from a mouse to the
embryo of the pigs. This has reduced the output by more than 70% making the pigs more environmental
friendly.
Genetic engineering has also led to the production of more variants in genetics. This can be proven by the
creation of the venomous cabbage, which was genetically engineered to limit the use of pesticide, and at the
same time prevent the cabbage from being damaged by caterpillars. This has been done by injecting these
cabbages with scorpion poison, which kills the caterpillars, but is harmless to the humans because the toxins
have been modified. Another example is the Flavr Savr tomato, which was modified by the addition of
antisense gene that helped in reducing the softening and rotting process without interfering with the color and
flavor of the tomato.
Genetic engineering has also been applied in the medical sector. People will soon be receiving vaccines by
biting bananas. The experts have engineered different vegetables such as bananas, lettuce, potatoes, tobaccos
and carrots to produce vaccines. Bananas are the ones that are ideal not only because of their production but
also their delivery. When the altered form of the virus for diseases such as cholera and hepatitis B, is injected in
the banana sapling, its genetic material will become a permanent part of the cells of the plant. As it grows the
cells will produce the virus of the proteins, but not its infectious part. This will help in building the immune
systems by boosting the antibodies, allowing the body to fight the disease similar to the traditional vaccine.
Another example of genetic engineering in medicine includes the creating of medicinal eggs. These eggs come
from genetically modified hens, in which the human gene has been added to their DNA. This causes the
secretion of the human protein and the medicinal proteins used in the treatment of diseases such as cancer into
the egg whites. These eggs will contain the miR24 molecule that is responsible for treating arthritis, malignant
melanoma. It will also contain the antiviral drug called human interferon b-1a, which is similar to the treatment
for multiple sclerosis.
Genetic Engineering Techniques
There are a number of techniques for moving genes artificially into recipient organisms. The oldest of
these is called recombinant DNA, a technique that relies on biological vectors like plasmids or viruses.
Other newer gene transfer techniques are electro- and chemical poration, microinjection, and
bioballistics.
Recombinant DNA
Recombinant DNA techniques use biological vectors like plasmids and viruses to carry foreign genes into cells.
Plasmids are small circular pieces of genetic material found in bacteria that have the ability to cross species
boundaries. The circles can be broken and new genetic material added to them. Plasmids augmented with new
genetic material can move across microbial cell boundaries and place the new genetic material next to the
bacterium's own genes. Often the bacteria will take up the gene and begin to produce the protein for which the
gene codes. Where the new gene codes for insulin, for example, the bacterium will begin to produce insulin
along with its other gene products. A large vat of bacteria engineered to produce insulin can then become a sort
of pharmaceutical factory.
Viruses can also act as vectors in genetic engineering. Viruses are infectious particles that contain genetic
material to which a new gene can be added. The virus can carry the new gene into a recipient cell in the process
of infecting that cell. The virus can also be disabled so that while it can carry a new gene into a cell, it cannot
redirect the cell's genetic machines to make thousands of copies of itself.
Microinjection
Other methods do not rely on biological vectors like plasmids and viruses. One of these is called microinjection
and involves simply injecting genetic material containing the new gene into the recipient cell. Where the cell is
large enough, as many plant and animal cells are, the injection can be done with a fine-tipped glass needle.
Somehow the injected genes find the host cell genes and incorporate themselves among them.
Electro- and Chemical Poration
Other methods for direct gene transfer involve creating pores or holes in the cell membrane to allow entry of the
new genes. This can be done by bathing cells in solutions of special chemicals—so-called chemical poration—
or subjecting cells to a weak electric current—so-called electroporation.
Bioballistics
Finally, there are so-called projectile methods that use metal slivers to deliver the genetic material to the interior
of the cell. The small slivers (much smaller than the diameter of the target cell) are coated with genetic material.
One projectile method, called bioballistics, propels the coated slivers into the cell using a shot gun. A perforated
metal plate stops the shell cartridge, but allows the slivers to pass through and into the living cells on the other
side. Once in the cell, the genetic material is transported to the nucleus where it is incorporated among the host
genes.
Last Revised: 07/18/03
Genetic Engineering in Agriculture
Few topics in agriculture are more polarizing than genetic engineering (GE), the process of manipulating an
organism’s genetic material—usually using genes from other species—in an effort to produce desired traits such
as higher yield or drought tolerance.
GE has been hailed by some as an indispensable tool for solving the world’s food problems, and denounced by
others as an example of human overreaching fraught with unknown, potentially catastrophic dangers.
UCS experts analyze the applications of genetic engineering in agriculture—particularly in comparison to other
options—and offer practical recommendations based on that analysis.
Benefits of GE: Promise vs. Results
Supporters of GE in agriculture point to a multitude of potential benefits of engineered crops, including
increased yield, tolerance of drought, reduced pesticide use, more efficient use of fertilizers, and ability to
produce drugs or other useful chemicals. UCS analysis shows that actual benefits have often fallen far short of
expectations.
Health and Environmental Risks
While the risks of genetic engineering have sometimes been
exaggerated or misrepresented, GE crops do have the potential to cause a variety of health problems and
environmental impacts. For instance, they may produce new allergens and toxins, spread harmful traits to weeds
and non-GE crops, or harm animals that consume them.
At least one major environmental impact of genetic engineering has already reached critical proportions:
overuse of herbicide-tolerant GE crops has spurred an increase in herbicide use and an epidemic of herbicideresistant "superweeds," which will lead to even more herbicide use.
How likely are other harmful GE impacts to occur? This is a difficult question to answer. Each crop-gene
combination poses its own set of risks. While risk assessments are conducted as part of GE product approval,
the data are generally supplied by the company seeking approval, and GE companies use their patent rights to
exercise tight control over research on their products.
In short, there is a lot we don't know about the risks of GE—which is no reason for panic, but a good reason for
caution.
What Other Choices Do We Have?
All technologies have risks and shortcomings, so critics must always address the question: what are the
alternatives?
In the case of GE, there are two main answers: crop breeding, which produces traits through the organism’s
reproductive process; and agroecological farm management, which seeks to make the most of a plant’s
existing traits by optimizing its growing environment.
These approaches are generally far less expensive than GE, and often more effective. The biotechnology
industry has acknowledged the value of breeding as a complement to GE. But at the same time, the industry has
used its formidable marketing and lobbying resources to ensure that its products—and the industrial methods
those products are designed to support—continue to dominate both the seed marketplace and the policy
conversation, at the expense of ecologically based, diverse farming systems.
Does UCS Have a Position On GE?
Yes. We see that the technology has potential benefits, but we are critics of its commercial application and
regulation to date. GE has proved valuable in some areas (as in the contained use of engineered bacteria in
pharmaceutical development), and some GE applications could turn out to play a useful role in food production.
However, its applications in agriculture so far have fallen short of expectations, and in some cases have caused
serious problems. Rather than supporting a more sustainable agriculture and food system with broad societal
benefits, the technology has been employed in ways that reinforce problematic industrial approaches to
agriculture. Policy decisions about the use of GE have too often been driven by biotech industry PR campaigns,
rather than by what science tells us about the most cost-effective ways to produce abundant food and preserve
the health of our farmland.
These are a few things policy makers should do to best serve the public interest:
1. Expand research funding for public crop breeding programs, so that a broad range of non-GE
as well as GE crop varieties will remain available.
2. Expand public research funding and incentives to further develop and adopt agroecologically
based farming systems.
3. Take steps—such as changes in patent law—to facilitate independent scientific research on GE
risks and benefits.
4. Take a more rigorous, conservative approach to GE product approvals, so that products do
not come to market until their risks and benefits are well understood.
5. Support food labeling laws that require foods containing GE crops to be clearly identified as
such, so that consumers can make informed decisions about buying GE products.
Last Revised: 08/22/12
Failure to Yield
For years the biotechnology industry has trumpeted that it will feed the world, promising that its genetically
engineered crops will produce higher yields.
That promise has proven to be empty, according to Failure to Yield, a report by UCS expert Doug GurianSherman released in March 2009. Despite 20 years of research and 13 years of commercialization, genetic
engineering has failed to significantly increase U.S. crop yields.
Failure to Yield is the first report to closely evaluate the overall effect genetic engineering has had on crop
yields in relation to other agricultural technologies. It reviewed two dozen academic studies of corn and
soybeans, the two primary genetically engineered food and feed crops grown in the United States. Based on
those studies, the UCS report concludes that genetically engineering herbicide-tolerant soybeans and herbicidetolerant corn has not increased yields. Insect-resistant corn, meanwhile, has improved yields only marginally.
The increase in yields for both crops over the last 13 years, the report finds, was largely due to traditional
breeding or improvements in agricultural practices.
The UCS report comes at a time when food price spikes and localized shortages worldwide have prompted calls
to boost agricultural productivity, or yield -- the amount of a crop produced per unit of land over a specified
amount of time. Biotechnology companies maintain that genetic engineering is essential to meeting this goal.
Monsanto, for example, was running an advertising campaign at the time of the report release warning of an
exploding world population and claiming that its “advanced seeds… significantly increase crop yields…” The
report debunks that claim, concluding that genetic engineering is unlikely to play a significant role in increasing
food production in the foreseeable future.
The biotechnology industry has been promising better yields since the mid-1990s, but Failure to Yield
documents that the industry has been carrying out gene field trials to increase yields for 20 years without
significant results.
Failure to Yield makes a critical distinction between potential—or intrinsic—yield and operational yield,
concepts that are often conflated by the industry and misunderstood by others. Intrinsic yield refers to a crop’s
ultimate production potential under the best possible conditions. Operational yield refers to production levels
after losses due to pests, drought and other environmental factors.
The study reviewed the intrinsic and operational yield achievements of the three most common genetically
altered food and feed crops in the United States: herbicide-tolerant soybeans, herbicide-tolerant corn, and
insect-resistant corn (known as Bt corn, after the bacterium Bacillus thuringiensis, whose genes enable the corn
to resist several kinds of insects).
Herbicide-tolerant soybeans, herbicide-tolerant corn, and Bt corn have failed to increase intrinsic yields, the
report found. Herbicide-tolerant soybeans and herbicide-tolerant corn also have failed to increase operational
yields, compared with conventional methods.
Meanwhile, the report found that Bt corn likely provides a marginal operational yield advantage of 3 to 4
percent over typical conventional practices. Since Bt corn became commercially available in 1996, its yield
advantage averages out to a 0.2 to 0.3 percent yield increase per year. To put that figure in context, overall U.S.
corn yields over the last several decades have annually averaged an increase of approximately one percent,
which is considerably more than what Bt traits have provided.
In addition to evaluating genetic engineering’s record, Failure to Yield considers the technology’s potential role
in increasing food production over the next few decades. The report does not discount the possibility of genetic
engineering eventually contributing to increase crop yields. It does, however, suggest that it makes little sense
to support genetic engineering at the expense of technologies that have proven to substantially increase yields,
especially in many developing countries. In addition, recent studies have shown that organic and similar
farming methods that minimize the use of pesticides and synthetic fertilizers can more than double crop yields
at little cost to poor farmers in such developing regions as Sub-Saharan Africa.
The report recommends that the U.S. Department of Agriculture, state agricultural agencies, and universities
increase research and development for proven approaches to boost crop yields. Those approaches should
include modern conventional plant breeding methods, sustainable and organic farming, and other sophisticated
farming practices that do not require farmers to pay significant upfront costs. The report also recommends that
U.S. food aid organizations make these more promising and affordable alternatives available to farmers in
developing countries.
“If we are going to make headway in combating hunger due to overpopulation and climate change, we will need
to increase crop yields,” said Gurian-Sherman. “Traditional breeding outperforms genetic engineering hands
down
High and Dry: Why Genetic Engineering Is Not Solving Agriculture's Drought Problem in a
Thirsty World
Droughts can be devastating to farmers and to the people who depend on the food those farmers produce. The
historic Texas drought of 2011 caused a record $5.2 billion in agricultural losses, making it the most costly
drought on record.
While extreme droughts capture the most attention, mild and moderate droughts are more common and
collectively cause extensive damage. Climate scientists expect the frequency and severity of such droughts to
increase as the global climate heats up.
Furthermore, agriculture accounts for the lion's share of water extracted from rivers and wells, setting up
conflicts between food production and other uses. Other important organisms, such as fish, also compete with
humans for fresh water. So there is a vital need for crop improvements that will increase drought tolerance and
water use efficiency (WUE).
Biotechnology companies such as Monsanto have held out the promise that genetic engineering can accomplish
these goals, creating new crop varieties that can thrive under drought conditions and reduce water demand even
under normal conditions. High and Dry offers an analysis of the prospects for delivering on that promise.
Extent and severity of drought conditions in the U.S. on August 30, 2011. The darker areas are regions of severe
to exceptional drought where cspB corn would likely be of little use. (Click on map for larger version with
legend.)
A Small Bang for Big Bucks
Though the mid-2000's saw a surge in field trials for crop varieties with engineered drought tolerance traits, as
of 2012 only one such variety—Monsanto's DroughtGard, containing the engineered gene cspB—had been
approved by the USDA.
The results so far paint a less than spectacular picture of DroughtGard's effectiveness: USDA analysis of data
supplied by Monsanto show that DroughtGard produces only modest results, and only under moderate drought
conditions at that. The report estimates that cspB corn would increase the overall productivity of the U.S. corn
crop by only about one percent. And DroughtGard does not improve water use efficiency.
The evidence suggests that alternatives to GE—classical breeding, improved farming practices, or crops
naturally more drought-tolerant than corn, such as sorghum and millet—can produce better results, often at
lower cost. If we neglect these alternatives because of exaggerated expectations about the benefits of GE, we
risk leaving farmers and the public high and dry when it comes to ensuring that we will have enough food and
clean freshwater to meet everyone's needs.
Why Drought Tolerance Is So Challenging
There are several reasons why a GE magic bullet for drought tolerance may prove elusive. Drought tolerance is
a complex trait that can involve many different genes, corresponding to different ways the plant can respond to
drought; genetic engineering can manipulate only a few genes at a time. And in the real world, droughts vary
widely in severity and duration, affecting the crop at different stages of its growth, so any engineered gene will
be more successful under some drought conditions than others.
Genes that improve drought tolerance may have other effects on crop growth, some of which may be
undesirable—a phenomenon known as pleiotropy. This has been commonly observed with many otherwise
promising drought tolerance genes, and is likely a reflection of the interconnectedness of drought response with
many other aspects of plant growth.
Molecular biologists try to reduce the negative effects of pleiotropy by ensuring that the engineered genes only
become active under drought conditions, but if droughts are prolonged, the harmful effects may be hard to
avoid.
Market Uncertainties
If Monsanto's cspB corn can meet these challenges, it will still face market hurdles. For starters, DroughtGard
will have to compete in the marketplace with drought-tolerant varieties produced through less expensive
breeding methods.
Another challenge for cspB corn is that farmers buy their seeds well before they plant. Because drought is not
reliably predictable, many farmers may not want to pay the higher price of engineered drought tolerance just in
case drought occurs. This may largely restrict planting of cspB corn mainly to areas where moderate drought is
frequent, such as the western regions of the U.S. Corn Belt.
Other factors important for marketing seed include the overall quality of the corn varieties that the cspB is
placed in and how these compare to competitors varieties.
Recommendations
Given the status of R&D on GE drought tolerance and water use efficiency and challenging questions about its
prospects, UCS recommends that:
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Congress and the USDA should substantially increase support for public crop-breeding programs
to improve drought tolerance.
Congress and the USDA should use conservation programs funded under the federal Farm Bill to
expand the use of available methods for improving drought tolerance and WUE.
The USDA and public universities should increase research devoted to finding better ways to store
and conserve soil water, groundwater, and surface water, and better farming methods to
withstand drought.
In particular, organic and similar methods that improve soil fertility simultaneously improve the
capacity of soil to store water for crop use during drought, while mulches can reduce soil
temperature and reduce evaporation. These methods should be encouraged through incentives.
Public and private research institutions should devote more funding and effort to improve crops
that are important in drought-prone regions in the Southern Hemisphere.
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Researchers at the USDA and public universities should carefully monitor the efficacy and possible
undesirable effects of cspB corn. Such monitoring is important because this variety is the first GE
commercial drought-tolerant crop, and the resulting information would enhance our
understanding of GE drought tolerance.
The USDA and public universities should expand their research on using plant breeding to
improve water use efficiency—a vital concern that has not attracted major efforts from the
biotechnology industry.
Last Revised: 05/10/12
Risks of Genetic Engineering
Technologies usually involve risks, and sometimes those risks turn out to be unexpected ones. DDT, for
example, turned out to accumulate in fish and thin the shells of fish-eating birds like eagles and ospreys. And
chlorofluorocarbons turned out to float into the upper atmosphere and destroy ozone, a chemical that shields the
earth from dangerous radiation.
What harmful effects might turn out to be associated with the use of genetically engineered (GE) organisms?
This is not a simple question. Answering it requires that we understand complex biological and ecological
systems.
So far, scientists know of no inherent, generic harms associated with GE organisms. For example, it is not true
that all GE foods are toxic or that all engineered organisms are likely to proliferate if released into the
environment.
But specific enginereed organisms may have specific harmful effects by virtue of the novel gene combinations
they possess. This means that the risks of genetically engineered organisms may vary widely, and therefore
must be assessed on a case-by-case basis.
So far, scientists have identified a number of ways in which GE organisms could adversely affect both human
health and the environment. Once the risks are identified and can be detected by regulators, the next step is risk
assessment: determining how likely potential harms are to occur.
In addition to risks that we can envision and attempt to assess, GE may pose risks that we simply do not know
enough to identify. This possibility does not in itself justify trying to suppress the technology, but it does put a
substantial burden on its advocates to demonstrate benefits.
Health Risks
New Allergens in the Food Supply
GE crops could produce new allergens in foods, which sensitive persons would not know to avoid. For instance,
a gene for one of the many allergenic proteins found in milk might be transferred into vegetables such as
carrots. A mother who knows better than to give her sensitive child milk would not realize that she needed to
avoid GE carrots with the allergenic milk protein. This problem is unique to GE, because it alone can transfer
proteins to completely unrelated species—often from organisms that have never been consumed as foods.
Research has substantiated concerns about GE rendering previously safe foods allergenic. For instance, a
University of Nebraska study showed that soybeans engineered to contain Brazil nut proteins cause reactions in
people allergic to Brazil nuts. Scientists have limited ability to predict whether a particular protein will be a
food allergen, so importing proteins—particularly from non-food sources—is a gamble with respect to their
allergenicity.
Antibiotic Resistance
Most genetically engineered plant foods carry fully functioning antibiotic-resistance genes, which are used as
"selectable markers" early in the engineering process, helping to select cells that have taken up the foreign
genes. Such genes could have two harmful effects. First, eating these foods could reduce the effectiveness of
antibiotics to fight disease if the antibiotics are taken at the same time as the foods. Second, the resistance genes
could be transferred to human or animal pathogens, making them impervious to antibiotics—an effect that has
already been demonstrated experimentally in the human digestive system.
Production of New Toxins
Many organisms have the ability to produce toxic substances, which help to defend them from predators. Some
plants contain inactive genetic pathways leading to toxic substances, and new genetic material introduced
through GE could reactivate these pathways or otherwise increase the plant's production of toxic substances.
This might happen, for instance, if on/off signals associated with an introduced gene are located on the genome
in places where they could turn on the previously inactive genes for producing the toxins.
Concentration of Toxic Metals
Some genes added to crops can remove heavy metals like mercury from the soil and sequester them in the plant
tissue. This allows the use of municipal sludge, which contains toxic heavy metals, as fertilizer. The crops are
engineered to concentrate the heavy metals in parts of the plant that are not eaten—a tomato's roots or a potato's
leaves, for example. This is done through genetic on/off switches that operate only on specific tissues. However,
if the on/off switches are not completely turned off in edible tissues, there is a risk of contamination. There are
also environmental risks associated with the handling and disposal of the contaminated parts of plants after
harvesting.
Enhancement of the Environment for Toxic Fungi
Although most GE health risks result from adding new genetic material to organisms, the removal of genes and
gene products can also cause problems. For example, GE might be used to produce decaffeinated coffee beans
by deleting or turning off genes associated with caffeine production. But caffeine helps protect coffee beans
against fungi. Beans that are unable to produce caffeine might be coated with fungi, which can produce toxins.
Fungal toxins, such as aflatoxin, are potent human toxins that can remain active through processes of food
preparation.
Environmental Risks
Increased Weediness
Serious weed problems can result when a plant is introduced—either accidentally or intentionally—into an
environment where it inhibits crop yields or disrupts ecosystems. GE has the potential to create weed problems
by adding traits that enable a plant to thrive unaided in environments where it becomes a new weed. One
example would be drought-tolerant turfgrass or switchgrass, which may become invasive in drier environments.
Gene Transfer
Novel genes engineered into crops can easily move via pollen to wild or weedy relatives of those crops that may
be growing nearby. The new traits might confer on those relatives the ability to thrive in unwanted places.
Several wild relatives of crops in the U.S., such as jointed goatgrass (a wheat relative), are already serious
weeds—and gene transfer could exacerbate this problem. (A related but distinct problem is gene contamination
of non-GE crops by nearby GE crops.)
Change in Herbicide Use Patterns
Widespread use of herbicide-tolerant crops has led to the rapid evolution of resistance to herbicides in weeds as
a result of increased exposure to the herbicide. As these herbicides become less effective, farmers may increase
their use of older, more toxic herbicides, with resulting environmental harm.
Squandering of Valuable Pest Susceptibility Genes
Many insects contain genes that render them susceptible to pesticides. These genes are a valuable natural
resource because they allow pesticides to remain effective. "Bt crops," which are genetically engineered to
contain a gene for the Bacillus thuringiensis (Bt) toxin—one of nature's most valuable pesticides—threaten the
continued susceptibility of pests to the Bt toxin. Because the crops produce the toxin throughout the life cycle of
the plant, pests are constantly exposed to it. This continuous exposure selects for the rare resistance genes in the
pest population and in time will render the Bt pesticide useless, unless specific measures are instituted to avoid
the development of such resistance. (Bt resistance has already been observed
Poisoned Wildlife
Addition of foreign genes to plants could also have serious consequences for wildlife in a number of
circumstances. For example, engineering crop plants, such as tobacco or rice, to produce plastics or
pharmaceuticals could endanger mice or deer who consume crop debris left in the fields after harvesting. Fish
that have been engineered to contain metal-sequestering proteins (such fish have been suggested as living
pollution clean-up devices) could be harmful if consumed by other fish or raccoons.
Creation of New (or Worse) Viruses
One of the most common applications of genetic engineering is the production of virus-tolerant crops. Such
crops are produced by engineering components of viruses into the plant genomes. For reasons not well
understood, plants producing viral components on their own are resistant to subsequent infection by those
viruses. Such plants, however, pose other risks of creating new or worse viruses through two mechanisms:
recombination, in which plant-produced viral genes and genes of incoming viruses recombine to produce
viruses that are more virulent or can infect a wider range of hosts than the parent viruses; and transcapsidation,
in which plant-produced viral proteins encapsulate the genetic material of another virus, producing a hybrid
virus that could transfer viral genetic material to a new host platn that it could not otherwise infect.
Unknown Risks
Each of the risks described above is an answer to the question, "well, what might go wrong?" The answer to that
question depends on how well scientists understand the organism and the environment into which it is released.
And since that understanding is incomplete, it is unlikely that all potential harms to human health and the
environment from the use of genetically engineered organisms have been identified.
Risk Assessment
How likely are any of these potential harms to occur? The answer to this question, again, depends greatly on
how well the organisms and their interaction in the environment are understood. Risks must be assessed case by
case as new applications of genetic engineering are introduced. In some circumstances, it is possible to assess
risks with great confidence. For example, it is vanishingly unlikely that genetically engineered palm trees will
thrive in the Arctic regardless of what genes have been added. But for many potential harms, the answers are far
less certain.
Risk assessments can be complicated. Because even rigorous assessments involve numerous assumptions and
judgment calls, they are often controversial when they are used to support particular government decisions.
Under the current US regulatory framework for biotechnology, some sort of risk assessment is routinely
produced before decisions to allow commercialization of products under the Federal Plant Pest Act; the Federal
Insecticide, Fungicide, and Rodenticide Act (FIFRA); and the Toxic Substances Control Act (TSCA). In the
case of the Plant Pest Act, risk assessments are done according to the procedure specified by the National
Environmental Policy Act (NEPA). Under NEPA, risk assessments could lead to full-blown environmental
impact statements, but so far all evaluations of engineered agricultural organisms have led to the legal
conclusion that no environmental impact statement is needed.
For the most part, risk assessments by scientists and policymakers in the relevant agencies (USDA or EPA) rely
on information provided by the companies seeking the approvals. The public often has a brief opportunity to
review and comment on the risk assessments.
There is no standard set of questions that risk assessments must answer because of the great range of potential
impacts of biotechnology products. A risk assessment for a microbial pesticide, for example, would be
substantially different from a risk assessment for genetically engineered salmon. Like all efforts at risk
evaluation, risk assessments done for regulation depend on the base of scientific knowledge underlying the list
of possible harms to be assessed.
Last Revised: 10/30/02
What are Genetically Modified (GM) Foods?
Although "biotechnology" and "genetic modification" commonly are used interchangeably, GM is a special set
of technologies that alter the genetic makeup of organisms such as animals, plants, or bacteria. Biotechnology, a
more general term, refers to using organisms or their components, such as enzymes, to make products that
include wine, cheese, beer, and yogurt.
Combining genes from different organisms is known as recombinant DNA technology, and the resulting
organism is said to be "genetically modified," "genetically engineered," or "transgenic." GM products (current
or those in development) include medicines and vaccines, foods and food ingredients, feeds, and fibers.
Locating genes for important traits—such as those conferring insect resistance or desired nutrients—is one of
the most limiting steps in the process. However, genome sequencing and discovery programs for hundreds of
organisms are generating detailed maps along with data-analyzing technologies to understand and use them.
In 2006, 252 million acres of transgenic crops were planted in 22 countries by 10.3 million farmers. The
majority of these crops were herbicide- and insect-resistant soybeans, corn, cotton, canola, and alfalfa. Other
crops grown commercially or field-tested are a sweet potato resistant to a virus that could decimate most of the
African harvest, rice with increased iron and vitamins that may alleviate chronic malnutrition in Asian
countries, and a variety of plants able to survive weather extremes.
On the horizon are bananas that produce human vaccines against infectious diseases such as hepatitis B; fish
that mature more quickly; cows that are resistant to bovine spongiform encephalopathy (mad cow disease); fruit
and nut trees that yield years earlier, and plants that produce new plastics with unique properties.
In 2006, countries that grew 97% of the global transgenic crops were the United States (53%), Argentina (17%),
Brazil (11%), Canada (6%), India (4%), China (3%), Paraguay (2%) and South Africa (1%). Although growth is
expected to plateau in industrialized nations, it is increasing in developing countries. The next decade will see
exponential progress in GM product development as researchers gain increasing and unprecedented access to
genomic resources that are applicable to organisms beyond the scope of individual projects.
Technologies for genetically modifying foods offer dramatic promise for meeting some of the 21st Century's
greatest challenges. Like all new technologies, they also pose some risks, both known and unknown.
Controversies surrounding GM foods and crops commonly focus on human and environmental safety, labeling
and consumer choice, intellectual property rights, ethics, food security, poverty reduction, and environmental
conservation (see GM Products: Benefits and Controversies, below).
GM Products: Benefits and Controversies
Benefits
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Crops
Enhanced taste and quality
Reduced maturation time
Increased nutrients, yields, and stress tolerance
Improved resistance to disease, pests, and herbicides
New products and growing techniques
Animals
o Increased resistance, productivity, hardiness, and feed efficiency
o Better yields of meat, eggs, and milk
o
o
o
o
o
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Improved animal health and diagnostic methods
Environment
o "Friendly" bioherbicides and bioinsecticides
o Conservation of soil, water, and energy
o Bioprocessing for forestry products
o Better natural waste management
o More efficient processing
Society
o Increased food security for growing populations
o
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Controversies
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Safety
Potential human health impacts, including allergens, transfer of antibiotic resistance
markers, unknown effects
o Potential environmental impacts, including: unintended transfer of transgenes through
cross-pollination, unknown effects on other organisms (e.g., soil microbes), and loss of flora
and fauna biodiversity
Access and Intellectual Property
o Domination of world food production by a few companies
o Increasing dependence on industrialized nations by developing countries
o Biopiracy, or foreign exploitation of natural resources
Ethics
o Violation of natural organisms' intrinsic values
o Tampering with nature by mixing genes among species
o Objections to consuming animal genes in plants and vice versa
o Stress for animal
Labeling
o Not mandatory in some countries (e.g., United States)
o Mixing GM crops with non-GM products confounds labeling attempts
Society
o New advances may be skewed to interests of rich countries
o
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Alternatives to Genetic Engineering
A key part of any benefits discussion involves alternatives. Are there better ways to do what is desired?
Like benefits, discussions of alternatives can be complicated and elusive, and much depends on the goals
envisioned. When the goals include reducing dependence on pesticides and herbicides, there are clearly
alternatives to many biotechnology products. Many of these alternatives are not other products, but
instead the systems and methods of sustainable agriculture.
A good example is crop rotation, which keeps pests under control elegantly by depriving them of the continuous
food supply they need to build up large populations. Crop rotation has many advantages. It controls a broad
variety of pests rather than just one or two. It does not select for resistance genes, as do chemical toxins or
genetically engineered crops. And it does not result in ongoing pollution of air or water. As a pest-control
strategy, crop rotation is far preferable to both chemical insecticides and genetically engineered crops.
Unfortunately, because it involves processes and not products, there is no industrial constituency to develop and
support crop rotation as there is for the products of biotechnology.
Conversion from industrial agriculture to sustainable systems that depend less on chemicals would eliminate the
need for many of the currently projected products of biotechnology. This is not to say that there is no place for
genetically engineered crops in sustainable systems; there may well be. But before such crops are introduced to
sustainable agriculture systems, those systems must be more fully developed than they currently are. The
specific products engineered for sustainable agriculture would be different from those that are being developed
to fit into industrial agricultural systems and their development should probably await the wider adoption of
such systems.
Agricultural biotechnology, as it is currently developing, is not particularly fruitful in the quest for a sustainable
agriculture. Sustainable agriculture solves problems by understanding and adjusting the elements of the system
to achieve its goals rather than by developing new products that must be purchased. Agricultural biotechnology,
by contrast, is basically an input industry, developing products, often expensive products, priced to cover the
costs of research and development. In sustainable agriculture, new products are less important than new
knowledge and new ways of manipulating agricultural ecosystems.