1.2 MYTH:

Genetic engineering is precise and the results are predictable


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 Promoters of GM crops paint a picture of GM technology that is based on a naïve and outdated understanding of how genes work.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 laser-like 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.

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