GMOs and agriculture: Facts, fears, and foods
Nicholas Turkey Breeding Farms,
Sonoma, California, USA
Proceedings of the 24th Technical Turkey Conference p.39
A large wave of feedstuffs derived from genetically engineered organisms
has recently flooded the market-place. Such increases should come as no
surprise to
anyone who has followed recent agricultural production trends: areas
planted in genetically modified crops have steadily increased from 1995-2000.
But the ability to
forecast such an increase is clearly distinct from predicting how such a
wave would upset the status quo. Predicting the arrival of a tidal wave is one
thing, but predicting how disruptive it might be is quite another. As we all
realize, public acceptance of genetically modified products has been anything
but calm.
Several months ago, when I was asked to speak at this meeting on
genetically modified organisms in agriculture, I naively agreed, confident that
I could master the subject and boil it down into a relatively few cogent bullet
points. I’ve been interested in this topic for some time, and I also have a
reasonable background in the molecular genetics of agricultural plants and
animals. What an opportunity – a great excuse to delve into the literature and
explore this contentious issue in some detail!
Now after grappling with this diverse literature, much of it dispersed
across multiple sites on the Web, I find it challenging to offer a concise
summary. The situation is
more akin to herding cats – I see considerable activity, many
interesting leads, numerous verbal exchanges and counter exchanges, and lots of
reasons for bystanders to notice that something is happening somewhere within
the dust cloud enshrouding GMOs. At the same time, it seems there has been
little actual progress in resolving the issues at hand. From the start, my goal
has been to present an objective assessment of the issues, pro and con, and a
brief overview of the science behind GM organisms. I deliberately emphasize GM
crop plants because this
technology and market penetration is so much greater for plants than for
animals. To cover this broad area, I touch upon the following topics.
Production Trends for GM Crops
Over 44 million hectares of GM crops were grown in 2000, about 75% of
this in the industrial nations. This is a land area almost twice the size of
the U.K. The pace of
increased planting slowed somewhat in the industrial nations after 1999
but continued to increase by 11% overall primarily due to continued production
increases in developing nations. As GM crops have increased in abundance,
pesticide usage has also changed. As more glyphosate-tolerant soybeans have
been planted, for example, glyphosate usage has increased while usage of other
herbicides has been reduced.
Consumer Benefits
Most of the GM crops being planted today contain genes affecting traits
offering economic advantages to producers rather than to consumers. With the
advantage
of hindsight, perhaps this was not a good way to begin. The Flavr-Savr
tomato, in which the softening that accompanies ripening was retarded, was an
early
exception. In this case, tomato harvesting could be delayed so that
fruit could ripen on the vine for a longer period, increasing fruit quality. In
terms of input traits,
however, consumers perceive themselves faced with increased risks from
GM foods, without noticing a concomitant reduction in price. Can you argue with
their
logic?
Developing GM Varieties
To-date, nearly all genetically modified crops trace their lineage to a
very few primary gene insertion events. Many such events were screened by trial
and error to identify the most desirable few. Subsequently, these few would have
been carefully studied, characterized, and thoroughly documented. Specific
details of these
descriptive studies are typically revealed in patents describing each
event as a novel invention. Projects of this scale ultimately yield a
proprietary product derived from one or a few gene insertion events, and they
are incredibly costly and time consuming. It is not economically feasible to
undertake such a project for
individual varieties or parental lines, so conventional breeding is used
to move engineered genes from one variety to others. It behooves us to remind
ourselves that
genetic engineering does not preclude the importance conventional
breeding – they must continue to operate in concert! Because successful
transfer and expression of foreign genes is infrequent, scientists routinely
use expression of a marker gene to identify putative candidates. To-date, most such marker genes confer resistance to
antibiotics. When grown in a medium containing an antibiotic, only antibiotic
resistant plants survive. Because of how foreign genes are inserted, many
antibiotic resistant plants will also contain the gene of commercial interest.
Antibiotic resistance is not an inherent property of GM crops, but instead a
technical vestige of the development process. The presence of antibiotic
resistance genes in GM crops
has fueled concerns about their safety, a topic to be discussed below,
and new marker gene technologies are being developed to circumvent this
weakness.
GM vs. Conventional Breeding Humans
have been selectively breeding plants and
animals for thousands of years, providing clear evidence of substantial
genetic modification over time. Indeed, both genetic engineering (i.e. transfer
and insertion of genes derived using recombinant DNA technologies) and conventional
breeding lead to genetic modifications! By the same token, genetic engineering
and conventional breeding are accomplished using very different strategies –
and both involve a high degree of uncertainty. I believe that understanding the
nature of this uncertainty is key to making progress in addressing public
concerns about GM
crops. The “bread and butter” of conventional breeding is to evaluate
the phenotypes of related individuals, and then select the best individuals as
parents for further breeding. Details vary substantially among species,
varieties, and individual programs, but this is the general scheme. Also included
within the conventional breeding framework are techniques such as wide crossing
(including inter-specific
hybridization), mutation breeding, and chromosomal manipulation. All of
these latter methods mimic events that indeed occur in nature, but only
infrequently.
Moreover, they all involve a high level of uncertainty – for each
success there are many failures, and only by testing can successes be
identified. It would seem reasonable that risks and uncertainties connected
with GM methods ought to be evaluated using the same standards of risks and
uncertainties associated with
conventional breeding.
Testing and Regulation of GM Products
Of the controversies surrounding GM products, perhaps their testing and
regulation are among the more contentious. Regulatory agencies (at least in the
U.S.) are being requested to expand their traditional areas of authority to
accommodate GMOs. Consequently, it is often unclear which of several agencies
is best suited to such an assignment. Regulatory approval for GM crops or products
can be obtained only after “adequate” testing has been completed, a situation
complicated by the lack of
clear regulatory authority. Regulatory ambiguity is a recognized problem
in the U.S., and steps are being taken to rectify it.
Food Safety
Uncertainties regarding the safety of GM products initially arose in
foodstuffs produced for human consumption. Among the more frequent questions
are concerns about the possibility of increased allergenicity of GM products,
adverse effects caused by consuming DNA from novel genes, and uncertainties
over possible
interactions between the products of novel and endogenous genes. Food
safety is a particularly sensitive issue for several reasons. First and
foremost, ready access
to an adequate supply of wholesome food is essential for all of us.
Second, recent incidents of food poisoning and disease outbreaks have caused
the public to mistrust
scientifically-based regulatory guidelines and the agencies authorized
to safeguard the integrity of food supplies. Finally, food safety has often
been used as a
political hot-potato. The public is forced to sift through an abundance
of confusing information and misinformation, a daunting task even to scientifically
literate
professionals. Concerns are now being raised, particularly in Europe and
in Japan, regarding the safety of meat products derived from animals fed GM
feed. Most
scientific evidence suggests that GM DNA and protein are quickly
degraded once they are consumed, but who should carry the burden of proof?
Clearly, these concerns could easily have significant affects on meat animal industries.
Environmental Impacts
Two arguments are often used to showcase negative environmental
consequences of GMOs. One regards the likelihood of accidental “escape” of
engineered genes into the biosphere, creating a race of superweeds (e.g. herbicide
tolerant) or perhaps accelerating the acquisition of antibiotic resistance
beyond the levels we already see. A second criticism is that built-in pest
resistance, as conferred by insertion of toxin genes from Bacillus thuringiensis (BT), may unduly affect
the viability of non-target organisms (e.g. Monarch butterflies). All are valid
concerns, and while the weight of scientific evidence suggests that detrimental
impacts have been overstated, critics argue that producers should bear the burden
of proof to establish the safety of GMOs. A different argument is the assertion
that planting GM crops containing herbicide tolerance genes actually encourages
herbicide use. Data do suggest, for example, that glyphosate usage has
increased as glyphosate tolerant crops have become more widely planted. But it
is also essential to point out that use of other herbicides – ones that are
less environmentally benign – has been reduced.
Therefore, a more comprehensive question is to what extent does the
planting of herbicide tolerant crops affect the net usage of all herbicides. Yet
another twist concerns the longer-term consequences of repeatedly using a
single management
practice. How quickly do weed species build up herbicide tolerance after
repeated use of glyphosate? Does widespread planting of BT-containing varieties
lead to BT
tolerance in insect species? If BT tolerance builds up, how quickly will
the conventional BT applications used by organic farmers become ineffective?
Relatively few studies have addressed these questions, and yet their logical
basis is scientifically valid. But despite their validity, keep in mind that
these are largely economic
questions, not questions of biosafety.
Product Labeling and Identity Preservation
The ability to label products as to their GM status requires that the
identity (or traceability) of GM vs. non-GM ingredients be maintained through
the production stream. Consumer groups have argued that product labeling would
preserve a consumer’s right to vote with their pocketbook. This may seem
reasonable at some level, but there are considerable costs associated with each
of the activities needed to ensure that labeling is properly done. These costs,
which would ultimately be passed along to consumers, would affect both GM and
non-GM products alike. How much are consumers willing to pay to learn whether
GM ingredients were (or could have been) used as an ingredient? To my
knowledge, this question has not been addressed and I suspect consumers are
largely unaware of it. As a related issue, what level of GM contamination might
be tolerated before a GM label is required? Is it reasonable that manufacturers
guarantee zero contamination? Keep in mind that manageable tolerance thresholds
are already in place for a wide variety of potential contaminants, even those
with well-known adverse affects. Such standards do not yet exist for GM
products.
Ethical Considerations
By their very nature, ethical questions are exceedingly slippery. What
business do we humans have interfering with nature? What right do corporations
have to patent DNA sequences or lifeforms? Are industrialized countries dumping
GM products into the marketplace of developing countries? On the other hand,
how is it ethical that affluent industrialized countries can impose their
self-motivated wishes upon the hungry citizens of developing countries? Golden
rice offers the potential to alleviate nutritional deficiencies – shouldn’t we
be ethically obligated to follow through with adequate tests to explore its
potential? In the area of ethics, there are many more questions than answers.
Hidden Agendas
As with many controversies, the motivations of various participants are
often questioned. Indeed, it is not merely a coincidence that the companies
developing herbicide resistant varieties also manufacturer the same herbicide. Do
they have a vested interest? Of course! How about grocery chains claiming
GMO-free products? Could their interest be to attract consumers into their
stores? Is it a coincidence that retailers of organic produce also own substantial
interests in organic farming enterprises? Is it curious that GM contaminants
were first reported by a commercial laboratory with a vested interest in the
test procedures, not to mention the tests themselves, needed to detect GM
contamination? Is there any connection
between the production of GM crops and agricultural protectionism? In
other words, we should not be surprised to see finger-pointing from those on
either side of the
issue. Many scientifically valid questions are already associated with
GM crops, and this situation becomes even more complicated once human
motivations come
into play.
Appropriate Responses?
Given the complexities and public sentiments surrounding the use of GMO
crops, how should we respond as an industry? In the short-term, we really have no
choice but to listen to our ultimate customers – the consumer public. At the
moment, the public’s voice seems to be saying no to GMO products – at least
this is the voice we’re hearing. How representative is this voice? How quickly
might it change? I see no simple answers to these questions, and so we must all
make the best decision we can given our business interests. In the longer-term,
however, we have the luxury of
helping to shape public opinion through outreach, education, and
professional activities. Both as an industry and as individuals, it behooves us
to pay attention to public opinion on GM products and to keep abreast of new
developments. It also makes sense to support scientifically-based rational
decision making, at least through our professional associations, if not also as
individual citizens. GM technologies have the potential to offer many advantages
to both producers and consumers, and yet the controversy surrounding GM products
is unlikely to subside quickly. In the long-run,I feel it is in society’s best
interest to actively participate in debating the pros and cons of GM technologies.
For further reading:
AgBioWorld.org. General information on GM plants, available at http://www.agbioworld.org/
Agricultural Biotechnology: Updated Benefit Estimates. National Center
for Food and Agricultural Policy, January, 2001.(http://www.ncfap.org/pup/
biotech/updatedbenefits.pdf)
Crops of Uncertain Nature? Controversies and Knowledge Gaps Concerning
Genetically Modified Crops, An Inventory. PlantResearch International, B.V.,
Wageningen, August 2000.
(http://www.mindfully.org/GE/ Knowledge-Gaps-Greenpeace-Wageningen.htm)
Foods from Genetically Modified Crops, Center for Molecular Agriculture.
(http://www.sdcma.org/GMFoodsBrochure.pdf)
information and links available through http://www.ucsusa.
org/index.html
Genetically Modified Foods: Are They Safe? Scientific American, April
2001. (http://www.sciam.com)
Transgenic Plants and World Agriculture. Prepared under the auspices of
the Royal Society of London, the U.S. National Academy of Sciences, the
Brazilian Academy of Sciences, the Chinese Academy of Sciences, the Indian
National Science Academy, the Mexican Academy of Sciences, and the Third World
Academy of Sciences. July, 2000. (http://www.nap.edu/catalog/9889.html)