Genetically modified crops: advantages and concerns

In a nutshell

Genetically modified crops are crops that have had their genes edited so farmers can have increased crop yields with plants that are less likely to get disease or be affected by insect attacks. This is to meet global food demands. Currently, there are no fresh genetically modified fruit or vegetables approved in the EU to be eaten by humans.

Genetically modified (GM) crops

By growing GM organisms, we could achieve global food security and many believe it is our moral obligation to do this so we can feed the world. GM crops have increased yields and can grow in poor soil and harsh environments. They can also be fortified with extra nutrients.

Herbicide-resistant and insecticide-resistant crops

Weeds reduce crop-plant yields and promote fungal diseases. This is why GM crops have genes inserted in their DNA that make them resistant to a particular herbicide. So when the field is treated with herbicide, the weeds are killed whilst the crop remains unaffected.

Some GM crops have been modified to be resistant to insect attacks.

Example

Bacillus thuringiensis is a soil bacterium that produces a natural insecticide. The gene that does this in the bacterium has been inserted into plants. These plants now make this insecticide protein that kills caterpillars that eat the crop. It only works on some insects such as butterflies and moths, which are the most serious pests.

Ecological effects

GM crops growing in the wild have been reported in many countries. They may cross-pollinate a wild or cultivated relative of the crop.

Example

GM oilseed rape has the genetic capability to cross-pollinate with eight wild relatives.

They may also swap genes with other GM crops.

Example

One study of $288$ oilseed rape plants in America found that two had 'man-made' genes for multiple pesticides.

A concerning ecological effect is the Bacillus thuringiensis insecticide protein gene affecting non-target organisms. Only insects that eat the crop should be affected, but some pollen from the GM crops is carried in the wind. This pollen could be toxic to other insects that are essential pollinators to crops and other plants. However, this is a rare effect as it would require a very high amount of pollen to be carried in the wind.

Safety concerns of GM organisms

GM microorganisms are used to produce various foods and food additives. Some GM plants and seeds are fed to animals that provide us with meat, milk and eggs. Genetic modification of viruses that are used to transfer genes may have safety concerns. This is because viruses can only reproduce in the cells of living organisms potentially leading to infection. The solution is to inactivate the genes in the virus that cause infection.

Examples

Escherichia coli (E. coli) is a bacterium that can be genetically modified. E. coli is found in our intestines and doesn't cause any harm. This is why it is safe to be modified.

Antibiotic resistance genes

During genetic modification, not all of the cells in the organism take up the foreign gene. These cells will be screened and removed. When the cells are modified, an antibiotic resistance marker is inserted into the organism's genome and the required gene is also inserted. These cells are then treated with an antibiotic and any cells that have not taken up the desired genes will die as they are not antibiotic resistant.

Assessing the safety of GM products

The EU (European Union) has very strict rules on the development of GM crops. This is due to a number of concerns about the safety of these crops. One concern is whether GM products may cause allergic reactions. Currently, no GM products have been found that cause new allergies or are more or less allergenic than existing crops. GM crops could be modified to become the solution to some food allergies.

Scientists have found no statistically significant differences in health impacts between GM and non-GM crops.

Recent studies have suggested GM crops can cause cancer. However, these studies are very controversial and scientists do not agree on this.

Herbicides are thought to be harmless to humans and break down quickly in the environment. However, it has been suggested that harmful effects may be caused by the herbicide itself and not the GM crop.

Example

A herbicide called glyphosate has been correlated with an increase in conditions such as autism and cancer.

Note: Remember correlation does not equal causation.

Ethical considerations

Some people may consider inserting genes from one organism into another unethical. This is because some religions suggest it is wrong to change the natural organisms that God has created. GM could be considered as 'playing God'.

Producing and marketing GM foods

Farmers cannot just collect and sow the seeds from GM crops as they will not breed true. Instead, they have to buy more for the next season from seed companies. Food producers must clearly label GM food. This is so customers can decide whether they buy them or not. Food manufacturers must ensure no other food is contaminated with GM ingredients.

Embryo transplants

Cloning is important in animals, it allows animal breeders to produce many animals with similar characteristics. This can be useful as it could enable high milk volumes or beef quality. Cloning is done by embryo transplants.

1.	A developing embryo is removed from a pregnant female early in pregnancy (the cells have not yet become specialised).
2.	The cells are separated and grown in culture.
3.	The embryos are then transplanted into host mothers.

In the future, it may be possible to genetically modify these embryos before implantation.

GM vs traditional methods

Whilst GM has revolutionised the production of pharmaceuticals (such as insulin), the ecological impact of GM crops may have made crop production worse. This, alongside ethical concerns, means many scientists do not believe genetic modification has lived up to its promise. This is why we have not yet abandoned traditional breeding programmes, which despite being slower, have a proven safety record and success rate.