GMO Myths and Truths

1.2 Myth: Genetic engineering is precise and the results are
predictable
Truth: Genetic engineering is crude and imprecise, and the
results are unpredictable
GM proponents claim that GM is a precise
technique that allows genes coding for the desired
trait to be inserted into the host plant with no
unexpected effects.
The first step in genetically engineering plants,
the process of cutting and splicing genes in the
test tube, is precise, but subsequent steps are not.
In particular, the process of inserting a genetically
modified gene into the DNA of a plant cell is
crude, uncontrolled, and imprecise, and causes
mutations – heritable changes – in the plant’s
DNA blueprint. 1 These mutations can alter the
functioning of the natural genes of the plant in
unpredictable and potentially harmful ways. 2,3
Other procedures associated with producing
GM crops, including tissue culture, also produce
mutations. 1
In addition to the unintended effects of
mutations, there is another way in which the GM
process generates unintended effects. Promoters
of GM crops paint a picture of GM technology that
is based on a naïve and outdated understanding
of how genes work. They propagate the simplistic
idea that they can insert a single gene with laserlike
precision and insertion of that gene will have
a single, predictable effect on the organism and its
environment.
But manipulating one or two genes does not
just produce one or two desired traits. Instead, just
a single change at the level of the DNA can give
rise to multiple changes within the organism. 2,4
These changes are known as pleiotropic effects.
They occur because genes do not act as isolated
units but interact with one another, and the
functions and structures that the engineered
genes confer on the organism interact with other
functional units of the organism.
Because of these diverse interactions, and
because even the simplest organism is extremely
complex, it is impossible to predict the impacts of
even a single GM gene on the organism. It is even
more impossible to predict the impact of the GMO
on its environment – the complexity of living
systems is too great.
In short, unintended, uncontrolled mutations
occur during the GM process and complex
interactions occur at multiple levels within the
organism as a result of the insertion of even a
single new gene. For these reasons, a seemingly
simple genetic modification can give rise to many
unexpected changes in the resulting crop and the
foods produced from it. The unintended changes
could include alterations in the nutritional content
of the food, toxic and allergenic effects, poor crop
performance, and generation of characteristics
that harm the environment.
These unexpected changes are especially
dangerous because they are irreversible. Even
the worst chemical pollution diminishes over
time as the pollutant is degraded by physical
and biological mechanisms. But GMOs are living
organisms. Once released into the ecosystem,
they do not degrade and cannot be recalled, but
multiply in the environment and pass on their GM
genes to future generations. Each new generation
creates more opportunities to interact with other
organisms and the environment, generating even
more unintended and unpredictable side-effects.
How can these unintended, unexpected and
potentially complex effects of genetic engineering
be predicted and controlled? Promoters of GM
crops paint a simplistic picture of what is needed
for assessing the health and environmental safety
of a GMO. But the diversity and complexity of
the effects, as well as their unpredictable nature,
create a situation where even a detailed safety
assessment could miss important harmful effects.
GMO Myths and Truths 11