Controversial GM food

Gene transfer between species a particular concern (Illustration Juan Casabuenas)

Gene transfer between species a particular concern (Illustration: Juan Casabuenas)

I am sure you already know, but just to be certain be aware that GM in this case stands for genetically modified. That means that specific genetic material with supposedly desirable traits are transferred from one organism to modify another by using genetic engineering. In case of food crops the final outcome will be a praised or loathed GM food.

Traditional breeding has achieved similar results in the past, but over much longer time frames. Today we are so much in a hurry that we have to take shortcuts. With genetic engineering it is not only possible to speed up the process, but genes can also be transferred between unrelated species, something that cannot be done by traditional breeding. The scope for exchanging genetic material is thus much wider when using genetic engineering, and in here lies part of the problem. It makes it so much more difficult to accurately predict how the environment will react to the new plants.

Traits that have been introduced with GM methods

So far GM foods have been designed for greater resistance to pests and viruses, higher nutritional value and longer shelf life. The bacterial gene Bt is one of the most commonly inserted. It produces an insecticidal toxin that is supposed to be harmless to people, but protect the plant against insect attacks. Some crops have been modified to make them more able to tolerate certain herbicides.

Pacific salmon has been modified with a growth hormone gene from Chinook salmon to make them grow twice as fast as normal fish. Apples have been modified to avoid browning.

Moving genes from one organism to another

Moving genes from one organism to another

Blindness is a possible result of vitamin A deficiency, common in some parts of the world. Thus golden rice was engineered to contain beta-carotene to boost dietary vitamin A intake.  Genetic modification of oil seed crops could form an important part of the future omega-3 supply. Concerns about climate change may lead to increased development and use of drought-tolerant GM food crops.

These are just a few of many examples. Supporters of GM technology argue that crops should be genetically engineered to better feed a hungry world, making them able to grow under harsher conditions and simultaneously provide better nutritional profiles. They also claim that insect-repelling crops can protect the environment by minimising pesticide use and that herbicide-tolerant crops might allow less tilling and thus reduce the release of greenhouse gases.

The fear that GM technology is getting out of hand

But not all is rosy. Critics of the technology fear that GM foods could have possible unexpected adverse health effects, cause environmental damage and lead to commercial exploitation of farmers.  There is also a plausible threat that the modified crops could become insidious superweeds, or that they could genetically pollute the environment by accidentally breed with wild plants or other crops. This could be a potentially serious problem if crops engineered to produce pharmaceutical drugs accidentally cross breed with food varieties.

Public health issues are probably of least concern. However, if not careful in the testing, new allergens could be inadvertently created and known allergens could be transferred from traditional foods into GM foods. This was shown when a gene from the brazil nut was introduced into soybeans. People with allergies to brazil nuts were also allergic to the genetically modified soybeans.

To be clear, although public health risks seems to be small, this conclusion is based on minimal research into potential acute or chronic health risks of using GM foods. The mantra has been that they are basically equivalent to the conventional variety, except for the specific gene introduced by genetic engineering.

Broad public concerns about GM foods

Broad public concerns about GM foods

In contrast to public health issues, environmental concerns are very real and already proven. A large number of field trials have shown that gene transfer does occur between conventional and GM crops. Since bees cannot distinguish GM from conventional crops, GM crops can affect non-GM and more seriously organic crops through cross-pollination. Conventional varieties of major food crops have already been contaminated by incursions of GM crops. The most astounding example was the find of transgenes from GM maize used for food production in the USA in wild maize varieties in Mexico.

Pollen from GM plants have been shown to be carried with the wind for tens of kilometres.  GM crops can cross-breed with surrounding vegetation, including weeds, transferring undesired characteristics. The introduction of glyphosate-resistant soybeans in 1996 also produced glyphosate-tolerant weeds that have driven even greater use of herbicides.

Little thought has been given to the development of pests resistant to inbuilt insecticides. This is particularly relevant for the common genetic modification of some crops to produce the natural biopesticide Bacillus thuringiensis (Bt) toxin.  Many experts agree that such insect-repelling plants will speed the evolution of insecticide-resistant pests, something so obvious in conventional agriculture when spraying exclusively with one insecticide.

Growing GM crops on a large scale may affect the balance of other plants and wildlife in the environment.

But there is more

Concerns about the social and ethical issues surrounding genetic modification include the possible monopolisation of the world food market by large multinational companies that control the distribution of GM seeds. Concerns also relate to the use of genes from animals in plant foods. For example, eating traces of genetic material from pork is problematic for certain religious and cultural groups.

Animal welfare could be adversely affected. For example, cows given potent GM growth hormones could suffer from health problems related to their growth or metabolism. New GM organisms could be patented so that life itself could become commercial property.

Ground control I think we have a serious problem.


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