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Food under the microscope Tuesday, 6 April, 1999, 15:31 GMT 16:31 UK
Genetically-modified Q&A
GM foods graphic
Genetically modified foods will soon affect all our lives
Genetically-modified (GM) food has become a major health and environmental issue in the UK. It has sharply divided opinion, between those who believe the new technology will greatly enhance our lives and those who fear it will prove a scientific "advance" too far.

Below BBC News Online answers some of the key questions.

What is GM food?
How new is it?
When was it invented?
How does the technology work?
What are the potential health risks?
Are there health benefits?
Can we trust our food?
What are the green issues?
How do I know what I am eating?
Who controls GM food?

What is GM food?

Genetically-modified (GM) food is produced from plants or animals which have had their genes changed in the laboratory by scientists.

Food under the microscope
All living organisms have genes written in their DNA. They are the chemical instructions for building and maintaining life. By modifying the genes, scientists can alter the characteristics of an organism.

We might, for examples, want to boost yields, increase muscle bulk and make our crops and farm animals resistant to disease. Genetic engineering holds out these possibilities.

However, the technology is in its infancy. Very few food crops have been gene-altered using the new techniques, and there are no foodstuffs on sale in the UK made from GM animals.

And none of the GM crops currently being commercially grown around the world contain genes transferred from animals or humans.

Some will argue that this new technology is "unnatural". Others will point to the commonality that exists between species - from bugs and worms to monkeys and humans, we already share many of the same genes.
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How does this technology differ from what went before?

Farmers have been engaged in what we might term "traditional genetics" for thousands of years. They have long understood that like begets like, favouring the seed from plants with the most desirable characteristics.

New plant types have also arisen by cross-breeding closely-related species. This is how we got oil seed rape and bread wheat.

But way genes are passed from one generation to the next through sexual reproduction is something of a lottery.

Scientists have tried to speed things up by exposing experimental plants to chemicals and radiation. This has the effect of producing hundreds of mutations among the genes. Some of these may be useful, others will not and the plants will be discarded.

Genetic engineering, on the other hand, is more specific. It allows scientists to select a single gene for a single characteristic and transfer that stretch of DNA from one organism to another - even between different species.

An example of genetic engineering is the FlavrSavr tomato developed by Calgene. When tomatoes ripen, a gene is triggered to produce a chemical that makes the fruit go soft and eventually rot.

Scientists have now modified the gene which has the effect of "switching off" the chemical. As a result, the FlavrSavr tomato softens more slowly, meaning it can stay longer on the vine to develop a fuller taste. Its longer shelf life also reduces waste.
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When was GM food invented?

The first transgenic plant - a tobacco plant resistant to an antibiotic - was created in 1983. It was another ten years before the first commercialisation of a GM plant in the United States - a delayed-ripening tomato - and another two years (1996) before a GM product - tomato paste - hit UK supermarket shelves.

1996 was also the year that the EU approved the importation and use of Monsanto's Roundup Ready soya beans in foods for people and feed for animals. These beans have been modified to survive being sprayed with the Roundup herbicide that is applied to a field to kill weeds.

This soya, together with GM maize, is now used in a variety of processed foods on sale in UK shops. The products range from crisps to pasta.

A genetically-engineered version of the milk-clotting enzyme chymosin is also used in cheese-making.
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How does the technology work?

Scientists have developed a number of techniques for getting a desired gene into a plant. One technique makes use of a soil bacterium, Agrobacterium tumefaciens.

This microbe, dubbed the "first genetic engineer", has evolved the ability to insert stretches of DNA into plants. The bacterium does this to make plants produce the particular chemicals it needs to survive. Scientists get A. tumefaciens to deliver genes of their choice.

Labs also use a technique called biolistics. This uses a gun to fire the desired gene into a plant's cells. The "foreign DNA" is carried on tiny pieces of gold. With luck, the plant will take up the DNA and start to read out its instructions. Wheat and rice have been modified in this way.

Another method relies on protoplasts. These are plant cells which have had their tough walls removed. This gives the foreign DNA easier access to the cell interior.

All these techniques depend on the remarkable fact that many plants can be regenerated from single cells or small pieces of plant tissue - as all gardeners who take cuttings know. This means a successful modification can be multiplied very quickly.
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Why do some people think this technology may be harmful to human health?

Critics argue that we do not know enough about the way genes operate and interact to be sure of what the outcome of any modification will be. They worry that the alterations could accidentally lead to substances that are poisonous or trigger allergies.

The anti-GM lobby is critical of the use of DNA from plant viruses and bacteria in the modification of crops - they fear this may also somehow trigger disease.

They have objected to the use of antibiotic-resistant marker genes in transgenic crops, which are included by scientists to test whether or not their main modifications have been successfully incorporated into a plant.

The critics argue the antibiotic-resistant genes could be passed to the micro-organisms that make us ill. If this happens, we might not have the necessary drugs to fight back.
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How do the genetic engineers counter these arguments?

They will tell you there is no evidence of any GM food on UK supermarket shelves having caused any ill effects.

They make the point that very many of the conventional foodstuffs in our supermarket have only got there after their non-GM, raw ingredients have been treated to remove undesirable or toxic substances - and that the regulatory structures that govern GM foods are, in many ways, far stricter than for conventional products.

Genetic modification might result in the emergence of new allergens, but so too can conventional plant breeding, they say. However, the new technology holds out the possibility of engineering such problems out of food.

The use of DNA from plant viruses and bacteria presents little risk - precisely because we are not plants. Cauliflowers are naturally infected with a virus that is commonly used in the laboratory for modification purposes, and we eat millions of the vegetables with no ill effects.

Furthermore, genetic modification allows us to improve not only the flavour, texture and shelf-life of food but also its nutritional value. We could boost the vitamin content of fruits and vegetables, incorporate anti-cancer substances, and reduce our exposure to the less healthy oils and fats.

Bioengineers have also given us a new word to describe plants that have been altered to have medicinal properties - "nutraceuticals".
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So can we trust the food we eat?

All food products, novel or otherwise, are subject to a system of regulation which should ensure safety and consumer confidence.

These regulations set standards or thresholds that must be met. Testing procedures are designed to pick up problems before products get on to the market. When we get ill as a result of eating food, it is usually because of poor practice somewhere along the line.

BSE/CJD is a very good example of this: the rendering and abattoir industries adopted ineffective procedures and failed to remove specified meat products from the human food chain.

Remember that we the consumers also have responsibilities. One of the reasons food poisoning cases have risen dramatically in recent years is because we have failed to store and prepare food properly in our own kitchens.
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What are the environmental concerns with GM crops?

The green lobby fears that some of the genes engineered into crops could "escape" and be transferred to other species where they might have adverse effects.

In particular, they are worried about genes that confer herbicide and insect resistance. They believe leakage of these genes could result in the emergence of "superweeds" and in the disappearance of familiar species of insects and birds as food chains become damaged.

They accuse the biotech companies of trying to "handcuff" agriculture by attempting to tie farmers into deals where they have little choice but to buy the GM seed and the designer chemicals to go with it.

Some of the biodiversity issues will be directly tested in the large-scale GM crop trials to be undertaken in the UK. It can be argued that the British countryside is already a "sick" place, where modern, intensive farming methods have inflicted immeasurable harm on the natural balance of things. The big question is whether the new technology will exacerbate the problems.

Bioengineers will argue that GM technology offers a chance to recover the situation. They say GM crops will require fewer chemicals that have low toxicity, are rapidly degraded and stay in the soil rather than being washed into rivers.

They will do this whilst at the same time producing higher yields. This could reduce pressure on those remaining uncultivated habitats.

Scientists are also investigating whether plants can be modified to produce new plastics and biofuels that would be kinder to the environment than the products based on oil.
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How do I know what I am eating?

The UK Government, together with industry, is attempting to produce better labelling of food - so that consumers know precisely what they are buying, be it in a supermarket or in a restaurant.

The current rules state that GM food has to be labelled unless "neither protein or DNA resulting from genetic modification are present".

In plain terms, this means the following: if a crop was modified to alter the composition of a food ingredient, for example starch or oil, then the food will have to be labelled - GM DNA or protein will quite clearly be present in the food.

If the crop was modified to protect it from, say, insect attack and no GM DNA or protein is present in the extracted and purified starch or oil, the food will not have to carry a label.

In this instance, the starch or oil would be chemically identical to those products that were obtained from "conventional crops". This is known as the concept of "substantial equivalence".

The GM labelling rules should satisfy those who wish to exercise a choice based on any perceived health threat, real or imagined. However, the idea of substantial equivalence means the rules will not satisfy those who object to GM foods on ethical or religious grounds.

They are still denied choice because there will be some foodstuffs on sale without a label whose manufacture has involved genetic modification at some stage in the production process.

In addition, all this presupposes that the tests used to detect "foreign" DNA or protein are foolproof - some scientists argue they are not.

This is one of the reasons why supermarkets are now going to sources where the origin and purity of raw materials can be guaranteed.
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Where is GM food grown?

There are up to 500 small experimental sites in the UK, but all GM food on sale in the UK has been grown aboard, much of it in the USA.
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Who is monitoring the safety of GM food?

There are European Union directives covering what are more generally known as genetically-modified organisms (GMOs). In the UK specifically, two committees offer advice to the government. They are composed of university academics and industry experts. The Advisory Committee on Releases into the Environment (ACRE) includes an environmentalist and the Advisory Committee on Novel Foods and Processes (ACNFP) has one consumer representative and an ethicist.

There are roles also for the Committee on Toxicity in Food, Consumer Products and the Environment (COT), the Food Advisory Committee (FAC) and the Health and Safety Executive (HSE). Any company that brings a GM food to market will have had to pass several expert committees - a process that takes many years.

The government has also promised a Food Standards Agency.
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This page only gives a brief account of some of the main points in the GM food issue. For more in-depth information see some of the dedicated sites in our links section.

Links to more Food under the microscope stories are at the foot of the page.


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