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Assessing
Benefits and Risks of
Genetically Modified Organisms
The term "Genetically Modified
Organism" or GMO has been
applied to plants and animals in
which techniques of recombinant
DNA have been used to introduce,
remove, or modify specific parts
of the genome of an organism.
The resulting organism may now
stably express a novel protein,
a protein with novel properties,
or carry a change in the
regulation of some of its genes.
Usually, such a change is
designed to improve the ability
of the organism to grow, for
instance by resisting pests or
using nutrients more
efficiently, or to improve the
usefulness of the organism to
us, for instance by improving
its nutritive value, by using it
to manufacture pharmaceutically
important molecules, or
employing it to carry out
environmentally important
processes such as digesting
environmental toxins.
Public discussion of the risks
of Genetically Modified
Organisms turn on a number of
different and not always related
issues. The discussion document
below is meant to serve as an
outline of the most important
scientific points for many of
these issues and to provide
references to more detailed
discussions of the subject. This
document explicitly does not
address the social and economic
impact of the use and
commercialization of GMOs.
Some general issues to
consider:
1. A new technique such as
genetic engineering may
allow novel products to be
produced, but there is no
scientific basis for the
technique used to initially
generate the plants or
animals to be a source for
concern. Therefore, it will
be necessary to consider
products on a "case-by-case"
basis. In some cases, a GMO
may not be different in any
significant way from a
classically bred organism;
in most cases, the
differences from a parent
organism will be more
defined and better
understood than in a classic
breeding experiment.
2. In a given case, is the
concern about the organism's
interactions with the
environment while it is
growing, or about the
interaction of a product
with the user? Both are
possible, but if only one is
of concern in a given case,
the solutions are rather
different. Particularly in
the latter case, the levels
of the novel material should
be relevant to determining
risk. As detection methods
for GMOs per se become more
and more sensitive, it
becomes possible to detect
very small quantities of a
GMO. The distinction between
a small contamination with
an organism able to
propagate itself and a small
contamination by a protein
or metabolic product, in a
form no longer able to
propagate itself, should be
kept in mind. The primary
focus of concern lies with
invasive, self-propagating
organisms.
3. Some of the concerns
about GMOs reflect general
concerns about loss of
genetic diversity and
dependence on large
companies for seeds and
other materials. These are
scientifically and socially
valid concerns that are
worthy of discussion, but
are not the subject of this
document. From the viewpoint
of geneticists, reduction in
genetic diversity of crop
plants, for whatever reason,
can increase the risk of
invasion by a single
virulent pathogen. Solutions
to the problem of loss of
genetic diversity, which are
not unique to GMOs, are
quite distinct from the
possible solutions for
organisms believed to pose a
direct threat to us or to
the environment. There is
nothing about GMOs, per se,
that limits the genetic
diversity of food crops, and
it is possible that heirloom
strains could be revived
with this technology.
4. Have both risk and
benefit been considered in
evaluating concerns? It is
never possible to totally
eliminate the unknown
complication, even when
using plants and animals
that arise naturally and
have been in use for many
years. A sense of proportion
needs to be maintained in
evaluating the nature of the
expected benefit and the
nature of the possible
problems.
I. How does a "GMO" differ
from the product of traditional
methods of breeding and
selection?
One of the arguments generally
advanced in support of GMOs is
that all of the plants and
animals used today in
agriculture and manufacturing
processes are the result of
years of selection and breeding.
Specific traits were chosen
while others were discarded.
This is what one might call
conventional genetic
modification or breeding, in
which we choose what we want out
of the many random possibilities
arising from mutation and the
natural exchange of genetic
information. Over the past
century, the definition of
conventional (or natural)
breeding was expanded to include
crosses between distantly
related species, forced
hybridization by cell fusion,
and mutagenesis. In general,
crops produced by these methods
are not regulated, genetic test
crosses are not required, and
there is little effort to
characterize changes in traits
unrelated to the property of
interest. For GMOs, the changes
are specific and directed, so
that we know what they are. In
addition, however, the limits of
what can be changed are much
broader. Genes from animals may
normally enter plants (and vice
versa) in limited quantities
under very special
circumstances; genetic
engineering allows specific
genes to be stably expressed in
a plant, possibly at high
levels. Therefore, while it is
not always the case, frequently
a GMO will have genetic
information we would be
surprised to find by classical
genetic manipulation methods.
It is important, however, to
keep in mind that it is not the
method of introducing foreign
genes by molecular techniques
per se that is likely to make a
given GMO different from
anything that might have
appeared or has appeared
naturally, but the nature of the
specific change that is made.
Therefore, a scientifically
valid evaluation of risks (and
benefits) needs to be tailored
to the specific plant and/or
product that is under
consideration; the properties of
one GMO are unlikely to be
shared by another. Much of the
concern by scientists about
labeling reflects the emphasis
that has been placed on every
GMO, that is, on the method of
construction per se, an issue
which is not scientifically
supportable. Labeling to
indicate significant changes in
the composition of the final
product, independent of the
method of construction, would be
a scientifically valid approach
to this issue, and indeed is
currently required by the Food
and Drug Administration (FDA).
II. Can we evaluate whether
or not a given GMO is likely to
pose unexpected (or expected)
risks that should limit its use?
From the beginning of the use of
recombinant DNA or genetic
engineering, first in bacteria
and eventually in plants and
animals as well, there has been
active discussion of whether
these methods might lead to
unexpected properties of the
engineered organisms and whether
those properties might be
harmful. The Recombinant DNA
Advisory Committee of the
National Institutes of Health (NIH)
first developed guidelines in
1976 for assessing these issues
and for working safely with
organisms in laboratories. The
general principles developed by
that committee and put to the
test for the last two decades
are directly relevant to the
issues discussed here, with one
major addition. Initially,
recombinant DNA was for use in
the laboratory, and while some
engineered organisms might be
expected to escape the
laboratory environment, they
were generally not designed to
thrive and establish themselves
outside the laboratory. More
recently, as this technology has
been applied to plants and
animals, many of these organisms
have been specifically designed
for use in agriculture or the
environment, where the
laboratory ideas of containment
are not relevant. Therefore, the
evaluation of risks and benefits
needs to take this into account,
and is the basis for many of the
concerns about general use of
this technology.
A. What needs to be
evaluated? Are the methods
for carrying out adequate
evaluations available?
Here is an outline of the
types of questions that are
asked in evaluating the
possible risks of
introducing a new organism:
The general question is:
In what ways might the
introduced changes expand or
contract the possible
properties of the final
product, with what possible
consequences? For an
example of an in-depth
analysis of a specific
postulated risk of one type
of GMO, see the set of
studies published in the
Proceedings of the National
Academy of Sciences, vol.
98, issue 21 (2001),
assessing the risk to the
Monarch butterfly population
from corn expressing
Bacillus thuringiensis (Bt)
toxin. These studies
conclude that the risk of
all but one sort of the
currently used corn
containing Bt toxin to the
overall Monarch population
is negligible. Note that
risk assessment per se does
not consider expected
benefits, an important part
of the equation as well.
1. As a living organism:
a. Is the new
gene expected to
change where this
organism can grow?
How fast it grows?
Is it likely to
change the
organism's ability
to exchange genetic
information with
other organisms?
b. Will this
new gene be
exchanged/spread to
neighboring
organisms by any of
the currently
understood
mechanisms? Is it
likely to be
expressed in the new
context? What might
the consequences of
that be?
c. Is the
engineered organism
supposed to affect
other organisms (act
as a pesticide, for
instance?). If so,
how specific is its
action? How specific
are alternative
treatments? Will the
capacity of this
organism to grow and
spread affect the
evaluation of
effects on other
organisms?
d. How stable
are the properties
of this organism?
Would a simple
change that might be
expected to arise
during wide-spread
growth increase the
concerns about the
properties of the
organism?
2. As a food/other
preparation:
1. Is the new
gene/other
modification
expected to produce
a change in the
protein composition
of the final
product? What new
protein(s) should be
produced? Would they
be expected to be
biologically active
in the final
product? After
ingestion/appropriate
use of the final
product? Would they
be expected to be
allergenic in the
final product?
2. How
much of this
material should be
present in the final
product? A very
small amount of a
potentially harmful
product should be
considered
differently from a
large amount of the
same product.
B. What is the process
for evaluating organisms to
be used in the environment?
The current process of
evaluation and approval of
organisms is described in
great detail in the
pertinent documents prepared
by the relevant regulatory
agencies. This is well
summarized on the
www.colostate.edu web
site, which also provides
links to the specific agency
regulatory documents. A
brief summary is provided
here:
1. Department of
Agriculture (USDA)
process: covers plant
pests, plants,
veterinary biologics
a.
Notification
required of
intention to field
test, including
characteristics that
suggest no toxicity
or pathogenicity for
non-target organisms
stability; if less
characterized or
more questionable
crops/genes, more
information must be
provided
b. To
commercialize, data
on effects,
possibilities of
spread, etc. must be
provided.
c. USDA can
retract permission
if there is evidence
plant is becoming a
pest.
2. Food and Drug
Administration (FDA)
process: covers food,
feed, food additives,
veterinary drugs, human
drugs and medical
devices
a.
Notification by
developer to FDA 120
days before
marketing, and
producers are
required to prove
product safety,
including
information on
allergenicity.
Additional testing
will depend on
expectations of
harmful ingredients,
new ingredients,
antibiotic
resistance, etc.
b. FDA has
authority to remove
food from market if
deemed unsafe.
3. Environmental
Protection Agency (EPA)
process: covers
microbial/plant
pesticides, new uses of
existing pesticides,
novel microorganisms
used commercially.
a. Reviews
data on nature of
product, its risks
and benefits.
C. How do we assess
relative risks?
In some cases, the
"precautionary principle" is
often applied to new
technology, asserting that
if there is any risk at all
to a new technology, then
that technology should be
avoided. Another method of
assessing new technology is
to apply the standard of
relative risk assessment in
which current methods are
compared to the proposed
technology. With regard to
genetically modified foods,
this avenue has led to the
consideration of the risks
relative to conventional
breeding and current
agricultural practices. For
example, if one variety of a
plant contains a gene for
herbicide resistance that
was identified by
mutagenesis and selection,
and another variety contains
a gene (or even the same
allele) that was introduced
by recombinant technology,
is the relative risk of
using these plants
different? A more
complicated issue arises
when disparate comparisons
are required: Does the risk
of spraying chemical
pesticides on crops outweigh
the risks of introducing
crops containing genes that
confer pesticide resistance
biologically?
III. Putting GMOs in
perspective:
Every year, thousands of
Americans become ill and die
from food contamination. This is
not a consequence of using GMOs,
but instead reflects
contamination from food-borne
bacteria. "Natural" food
supplements are widely used but
are generally not well-defined,
purified, or studied. As of
2000, 53% of the US soybean
crop, 65% of the corn crop, and
80% of rennet cheese was
genetically modified. As of this
writing, we are not aware of any
confirmed illnesses or other
harmful effects resulting from
genetically modified foods.
Although recent reports of
contamination of corn meal by
GMOs not approved for human
consumption led to several
claims of allergic response, to
date, none of those individuals
has been shown to contain
antibodies to the GM protein.
References:
A comprehensive set of
information and links to other
sites can be found at: http://cls.casa.colostate.edu/TransgenicCrops/
National Academy of Sciences
report
Genetically Modified
Pest-Protected Plants: Science
and Regulation
(http://books.nap.edu/catalog/9795.html).
US and other Government sites
describing regulatory process
and evaluation of risks and
benefits:
United States Regulatory
Oversight in Biotechnology:
http://www.aphis.usda.gov/biotech/OECD/usregs.htm
General outline of roles of
various government agencies.
Roles of specific agencies:
USDA Agricultural
Biotechnology Information
U.S. Food and Drug
Administration,
Bioengineered Foods page
U.S. Environmental
Protection Agency
Biopesticide Web Page
U.S. House of
Representative, Committee on
Science
The report "Seeds
of Opportunity",
released in April 2000,
assesses the benefits and
risks of
genetically-modified crops
and foods.
Report of the New Zealand
Royal Commission on
Genetically Modified
Organisms
Document developed by GSA Board
of Directors, November, 2001.
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