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Find Topic:   DNA & Genes ... Breeding v GM ... Coexistence ... GM & Environment ... Gene Escape
GM Food ... GM Food Safety Tests ... GM Animal Feed ... Biofuels
Scotland's Food & Drink Policy ... Cloning & GM of Animals ... Synthetic Biology
New Techniques / Gene Editing
This section provides short simplified summaries of some important aspects of GM at the present time. If you have further suggestions for suitable topics, please let us know. Further information on some of the subjects below can be found by clicking on "More detail", otherwise look elsewhere on this website, particularly in 'Learning Links' - which includes a Glossary. To see a short explanation of a term shown below in bold type move the screen cursor onto it. Numbered references in [brackets] are listed at the end of that section.

DNA and Genes

All plants and animals consist of tiny cells, each cell containing a long thread-like material called DNA, which is wound up into a very tight bundle. A gene is a section of the DNA thread within which are ‘written’ the details of one substance, called a 'protein'. A plant cell may contain many thousand genes, and the resulting proteins interact to build and regulate the plant. When plants or animals reproduce, genes from both parents appear in the offspring, in distinct groups. Proteins are the chemical tools and building blocks of life. DNA is like the design blueprint of the organism (life-form), defining all the complex biological mechanisms necessary to enable that species to survive in its usual environment.  See also 'Gene Escape' below.

Breeding versus GM

As mentioned above, each new generation of a plant or animal contains genes from both parents. Since genes determine the qualities of the organism the inheritance of genes was studied long before the chemistry was unravelled. Most of our commercial plants and animals are the result of selective breeding by patient farmers over thousands of years. This process results in the preferential selection of existing genes, within the same species, rather than any attempt to modify the genes themselves. Nor can breeding occur between different species. Sometimes selective breeding results in undesired side-effects since a gene is often responsible for several traits, some desirable, others not. Genetic Modification (GM) or Genetic Engineering is a more recent technology which uses invasive techniques, such as virus infection, or a type of gun, to move desired genes between different species. Extra genes are added, such as an artificial promoter gene and frequently another gene which confers resistance to an antibiotic. The new life-form may also contain gene fragments and its chemistry is often unstable. At the present time the process of introducing the artificial genes is imprecise and more often than not disrupts the delicately balanced interrelationships within the organism's gene set (genome). An important, more ordered alternative is marker assisted breeding, a technique that combines modern DNA analysis and natural reproduction.


'Coexistence' refers to the existence in close proximity of GM plants and non-GM plants, and is a very important issue at the moment in the UK and Europe. Careful regulation of coexistence would be essential for the effective segregation of food sources. The UK Government has stated that there will be no commercial growing of GM plants until the potential problems raised by coexistence have been addressed by new regulations.

While most of our GM regulations stem from European law, coexistence has been passed back to individual governments to regulate - the European Commission has issued certain guidelines, but these have been criticised as legally flawed. Problems potentially arise when GM crops contaminate other non-GM crops, particularly organic crops which have stricter standards for growing and prohibit the use of GM. Contamination can result from 'Gene Escape' (see below), and may significantly reduce the market value of the crop. In the US, Starlink maize (approved only for animals) caused widespread allergy problems when it got into the human food supply in 2000, and ProdiGene was prosecuted in 2002 when vaccine-producing maize escaped.

The question of financial liability is therefore crucial to coexistence, and this was recognised in a Green Party Bill presented to the Scottish Executive (the Scottish Government). Bizarrely, in the US the owners of patented GM genes have successfully sued farmers whose fields were contaminated with these genes. Coexistence might be less problematic if research had shown that GM crops pose no risks to the consumer and the environment. But despite what the GM industry says, and some civil servants and politicians may repeat, the risk studies that have been published indicate the very opposite. See 'GM Food Safety Tests' and 'GM & Environment'.

The Scottish Executive (Government) was due to hold a coexistence consultation with interested parties in the spring of 2006, but it was eventually announced that the consultation would be held over to the summer of 2007 - after the May elections to the Scottish Parliament. (see Archive 16/11/06) To date (March 2012), no such consultation has been arranged, while the new Government (Scottish National Party) has reiterated its intention to maintain a moratorium on planting GM crops. (see Archive 17/7/07, 25/11/07)

The English consultation closed in October 2006 but its proposals were heavily criticised and some aspects were considered to be illegal. The results of that consultation were published in November 2007 showing 95 percent of over 11,000 respondents opposed the Government's proposals. (see Archive 8/11/07) The UK Government says it will now await various developments, including pending and new research, and EU seed labelling thresholds.

It is worthwhile looking at that English consultation, since any Scottish consultation would likely cover the same issues in a similar format. Friends of the Earth have prepared some excellent information and a guide to submitting views. The submission by Friends of the Earth [791K] to the English consultation has also been published, including the legal opinion that the UK Government's current proposals are "legally and fundamentally flawed".

GM & Environment

The main argument in favour of today's GM crops is that they are said to suffer less loss from insect attack, or from weeds competing for soil nutrients. With herbicide-tolerant (GMHT) crops herbicides can be applied more freely to suppress weeds, while GM varieties that produce their own insecticide (Bt) should reduce losses from insect attack. These arguments are also taken a step further viz. that less herbicide will be used, while insect-resistant crops will need less insecticide sprays. These latter arguments are potentially appealing to environmentalists and politicians alike. In reality however, the overall effects of GM crops on the environment are far from benign.

In the US particularly, herbicide use initially decreased slightly but is now greater per acre than before GM crops arrived. This is partly the result of farmers spraying too liberally and from the emergence of stronger weeds that have evolved to withstand the herbicide (so a different herbicide is then needed). Glyphosate (the main ingredient of the Roundup herbicide used with 'RoundupReady' crops) is a powerful weedkiller that has toxic side-effects, particularly in commercial mixes.

In the UK the Farm Scale Trials held prior to 2004 had a very restricted environmental scope, but nevertheless showed that the cultivation of GM herbicide-tolerant oilseed rape (canola) and beet had a more detrimental effect on wildlife (which depends on the survival of a few weeds). The data from the trials of GM maize (corn) are now essentially irrelevant, since the comparison crop was sprayed with atrazine, a particularly noxious herbicide now banned in Europe.

GM crops that produce their own insecticide are also problematic. Research suggests that harmless insects - 'non-target species' - can be poisoned incidentally. On the other hand, the targeted parasitic insects have now evolved resistance to the Bt insecticide. There is also evidence from Asia that suggests Bt crops have a toxic effect on farm animals and humans.

Compounding these problems is the fact that most GM plants reproduce very successfully. They can spread their pollen several miles and may cross-breed with closely related plants - contaminating both weeds and non-GM crops with the undesirable traits. See 'Gene Escape' and 'Coexistence'.

The growing of GM crops is closely linked with the continuing use of monoculture, implying incidental destruction of wild plant, insect and animal life. Consequently many regard GM itself as a threat to 'biodiversity' - the wide variety of species in nature that gives ecological systems their robustness, and ultimately underpins human well-being. The 'sustainability' of GM agriculture is also in question, because of the large energy inputs associated with fertiliser use in monoculture as well as the disruption of ecosystems.

Regulations governing releases of GM organisms to the environment exist within European law, but several countries regard them as inadequate and have taken unilateral action to ban specific GM crops from cultivation, or create 'GM free zones'. However there is continuing pressure from the US to speed up the approvals process.

Gene Escape

When an artificial GM gene (transgene) has been engineered into a plant (or animal), that gene will generally be capable of surviving within that species through the process of natural breeding. As a result, the gene and its resultant traits can migrate into non-GM varieties of the same crop, or into weeds belonging to the same family. This is known as gene escape, or gene flow, and can result when GM pollen fertilises a non-GM plant. Cross-fertilisation can be minimised by separating the two sets of plants, but the distances required can be many miles for insect and wind pollination. If seed supplies are contaminated with GM seed (which has happened) not only will the crop be contaminated, but subsequent cross-fertilisation may also occur - so that rigorous controls are required to protect seed production. Stray seeds carried away on vehicles, animals or water, or volunteer plants can also result in gene escape. The European regulations presently allow for 'adventitious' contamination of a non-GM crop which is quite high at 0.9% - above that the crop must be labelled as GM. In addition to problems with consumer choice, gene escape has serious consequences when the transgene transfers a more dangerous trait to the plant e.g. from a pharmaceutical gene, or by creating a weed which is resistant to weedkiller. Both types of incident have already occurred. There is also a potentially more serious type of gene escape - resulting from horizontal gene transfer - where a highly mobile transgene or fragment is assimilated by a virus or bacterium, and confers extra powers on it.

GM Food

From the late 1990s onward, genetically engineered (GE) products were quietly introduced into the UK food supply: GM soya and maize imported from the Americas, animals raised on imported GM feed, GE food additives, and synthetic enzymes - used as 'processing aids'.

Soya is used widely, providing a flour, an oil and an emulsifier, lecithin. Maize (corn) appears in cereals and snacks, and provides the glucose syrup in sweets and soft drinks. Meat and dairy products often come from animals fed on imported GM plant material, such as soya protein, oil seed rape (canola) and maize. Additives and enzymes are used extensively by the food industry. One example of a GE enzyme is chymosin, used to produce hard cheeses. Many artificial flavourings can be produced by genetic engineering. But in none of these areas is genetic engineering essential, although chymosin allows some cheeses to be marketed as 'vegetarian' since it replaces the traditional enzyme, calf's rennet.

When plants are genetically modified, their DNA is forced to accept a number of foreign genes, but the exact locations of these genes and therefore their effects on the plant are initially unknown. Interactions between genes are highly complex, and as yet poorly understood. However, it is a plant's genes that determine its chemical makeup and whether it is safe to eat or not. So when gene changes are engineered there can be unforeseen side-effects, that only become evident later. Many types of GM crops also include a gene that causes the plant to produce its own insecticide (Bt).

While some efforts are made to avoid marketing a GE product that is obviously toxic, when an experimental soy bean with a gene from a brazil nut was tested, it was found to be potentially fatal to people with a nut allergy. And in 1989 an accident occurred in the United States after a food supplement, produced using GE, appeared on the market. Thousands of people suffered from an outbreak of EMS disease, which killed at least 37. The food supplement, L-tryptophan, was later found to contain minute amounts of highly toxic by-products.

The antibiotic resistance marker genes intentionally put into GM plants may transfer to bacteria, enabling the bacteria to withstand the effects of medical antibiotics. These genes cause widespread concern, but European law has been stretched and this practice is still authorised. Certain 'promoter' genes are also regarded as extremely dangerous by some scientists. It is likely too that GM crops, engineered to resist a specific herbicide, will contain significant residues of that herbicide. In 1997, when glyphosate-tolerant GM crops were first imported into Europe, the legally permitted levels of glyphosate herbicide in soya were raised two hundred times.

The main potential risks of GM foods are therefore allergic reaction, chronic ill-health and an increase in harmful organisms. Considering how serious these risks could be, the flaws in the regulatory system are striking. See 'GM Food Safety Tests' and 'GM Animal Feed'. Although many types of GM crops are already approved for import into Europe, the US in particular has exerted considerable pressure for more and faster approvals.

Despite the regulations, GM crops are increasingly contaminating non-GM food. In the US, Starlink maize (approved only for animals) caused widespread allergy problems in 2000. Another hazard on the increase, particularly in the US, is the cultivation of GM 'pharma crops' grown to produce cheap pharmaceuticals. Unbelievably, these are grown in open fields in the US and instances of food contamination have already occurred.

Finally there is the ongoing problem of food imports contaminated with GM varieties unauthorised in the EU - these have not even undergone the minimal scrutiny of European regulators. Imports of unauthorised Bt10 maize and LLrice601 from the US were eventually stopped by the regulators. The response from the US has been to press for a relaxation of the 'zero tolerance' rule on unauthorised GM products. Unfortunately the UK Food Standards Agency has so far taken a very lax attitude to contamination of this type. See News Archive.

The labelling of GM food in the UK now (since 2004) is marginally better than before, but there are several significant loopholes - see outstanding concerns listed (2 to 8) below, under 'Scotland's Food & Drink Policy'. Therefore it is still difficult for the consumer to identify products produced by genetic engineering - poorly regulated and often unlabelled. Only by purchasing food produced to 'organic' standards, which prohibit any use of GM, or from a supplier who can assure a non-GM source can the consumer avoid GM products.

GM Food Safety Tests

The nutritional value of our conventional foods has been studied scientifically for more than a century, along with food toxins. But the safety of GM food also depends on its unique makeup, and whether there is likely to be a greater risk associated with this. It is a plant’s genes which determine its chemical content and whether that plant is safe to eat. Genetic modification is itself a disruptive process, as well as inserting new genes which do not naturally exist in that species.  Many of today's GM crops contain a gene, an antibiotic resistance marker, that confers resistance to an antibiotic - this has the potential for interaction with medical treatment and was due to be banned in Europe (but the standards have now been weakened). Many GM crops are specially engineered to create poison against insect pests, others to produce a chemical which allows the plant to survive dowsing in weedkiller.  These are powerful chemicals and their production within the plant can be fully turned on, all the time, by their 'promoter' genes. Complex chemical changes are caused when a plant's genes are changed, and sometimes unforeseen side-effects. The gene collection (genome) of the GM plant may even be unstable and the results wildly unpredictable. The reality is each GM food is a unique new creation and potentially very different from the variety from which it was engineered.

To expedite the approval of GM food in the early days, the regulators and industry agreed the principle of ‘Substantial Equivalence’ – a set of vague rules, with no sound basis in science.  It states that if a GM food is assessed to be ‘substantially equivalent’ to its non-GM version, then it is safe to eat and need not be fully tested. GM foods are still approved using this principle.  The public might reasonably expect the industry to demonstrate by testing that their unique new foods are in fact safe for consumption, but their record on this to date is not good - the devil is in the detail. In fact the industry maintains it is impractical, even unethical, to carry out feeding trials on human subjects and instead asserts that in the US millions of people have been eating GM foods without apparent ill effect. Independent scientists simply dismiss this assertion, since this 'feeding trial' would not meet even the simplest scientific criteria, while most US consumers are not even aware when they are eating GM products - the industry has fought vigorously to avoid GM food labelling there.  Furthermore, there has been no significant research into the massive rise in food-related illness there in recent years.  Most research critical of GM has in fact been suppressed in one way or another, and some very inadequate animal studies are proffered by the industry as reassurance.  Part of the problem is that the industry is allowed to withhold critical information, preventing independent scrutiny, since it is said to be "commercial in confidence".

The chequered history of GM food testing goes back many years, and is set out very well in the book by Jeffrey Smith: "Seeds of deception" [see Resources List].  Dr Arpad Pusztai was one of the first scientists to raise concerns about the safety of GM food back in 1998, when he spoke out about problems in rats fed on GM potatoes.  He lost his job as a result, and the scientific establishment tried to dismiss his research as flawed, although he was in fact working to strict industry protocols.  Since then, Pusztai has continued to draw attention to the significant lack of meaningful GM food trials.  Human feeding trials are virtually non-existent, but one was carried out on patients in Newcastle who had had part of their intestine removed.  The results of that showed that transgenes survived the initial parts of the digestive process, and that there was gene transfer to gut bacteria - two points of concern which had been dismissed by the industry beforehand as virtually impossible.  The Chardon GM maize inquiry in 2002 exposed the ludicrous test results submitted as evidence of safety of the maize.  The more worthwhile research to date includes the Australian tests involving GM peas, which unexpectedly caused lung inflammation in mice, and were prevented from being commercialised [see Recent Developments 18/11/05], and several studies by Seralini et al [e.g. News Archive 24/6/14].
GM in Depth: Risks & side effects

GM animal feed

Huge quantities of GM maize and soya are imported to the UK from the US and Brazil to feed farm animals. In fact a recent Soil Association study shows nearly all milk, dairy products, pork and red meat (and some poultry meat) in UK supermarkets come from animals fed on GM crops.

Improvements to the regulation of GM products in 2004 resulted in GM animal feed being labelled, but not the resulting animal products. The main issues are, firstly, research has shown it is possible for GM genes from feed to end up in an animal's flesh or milk - consumers may well be unwittingly ingesting these synthetic substances. Secondly, several studies on animals fed on GM products show adverse effects on the animals themselves. Third, the continuing market for GM feed is now threatening the UK supply of GM-free food. And finally, due to the lack of product labelling, consumers are kept in the dark and given no choice in the matter - their simplest recourse is to eat 'organic' products, where the use of GM feed is barred.

Several major environmental organisations are campaigning against the use of GM animal feed - Greenpeace presented a petition of one million signatures to the European Commission in 2007 - and there has been a UK Parliamentary Early Day Motion open for MPs' signatures.
GM in Depth: Risks & side effects


The issue of biofuels has come to the fore since scientists highlighted the dangers of man-made climate change ('global warming'). A simple example of a biofuel is wood. As a tree grows, like most plants, it absorbs energy from the sun, nutrients and water from the soil, and carbon dioxide gas from the atmosphere. If the wood is eventually burned as a fuel most of the energy locked up in its chemicals is given up as heat and carbon dioxide is released to the atmosphere. There is a recycling of carbon (as dioxide): absorbed by the tree from the atmosphere and some years later returned to the atmosphere. So, overall there is no increase in carbon in the atmosphere.

Modern biofuels have a slightly more complex carbon cycle. For example, ethanol (ethyl alcohol) can be produced by fermenting food crops like grains and fruits, and wood alcohol, methanol, from wood, while 'biodiesel' is just purified vegetable oil. Clearly any land used to grow these crops for fuel is no longer available to produce crops for human consumption. Where fertile land is limited this generates pressure on fragile ecosystems, drives up the cost of food, and leads to shortages.

In addition, it is vital to calculate the overall energy balance and the carbon balance of the complete biofuel cycle. For example, if wood is grown naturally then burned locally there is a real net energy benefit, since most of the wood's energy originally came from sunlight. If on the other hand fertiliser is added to accelerate growth or if machines are used to cut and transport the wood, then the energy required to produce the fertiliser and fuel the machines subtracts from the net energy benefit. For example, liberal use of oil-based fertiliser followed by a long carry to the point of usage could well mean that the whole production cycle requires more energy in than it usefully provides - that would represent a loss of useful energy and a potential increase in the use of fossil fuel (hence more carbon release and global warming). Also, the clearance of large areas of land for cultivation will result in a further release of carbon, as the previous ground cover is left to rot (emitting carbon dioxide).

The biotechnology industry claims that genetic modification and 'synthetic biology' can create crops, trees and artificial life forms (e.g. algae) that are easier to process chemically into fuel - but the side effects of GM remain, as well as the questions of overall energy and carbon balance. Unfortunately many governments seeking quick solutions to climate change have enthusiastically seized on biofuels without pausing to question their disbenefits.
GM in Depth: Biofuels

Scotland's Food and Drink Policy

On 15th January 2008 the Scottish Government - which has the (devolved) responsibility for all aspects of GM - published a discussion paper and announced a period of public consultation on all parts of the food chain. The consultation ran until 25th April 2008 and its stated aim was to ensure "joined up" Scottish Government policy on the entire food chain. This is a very desirable goal and quite apart from unresolved GM issues the food chain has many other contentious aspects (e.g. misuse of supermarkets' power, food-miles, over-packaging, additives, etc). Here however we simply list certain points relating to GM which need to be addressed now - for detailed information on these refer to our website resources, particularly the 'Learning Links'
  1. The question of 'coexistence' (above) is crucial. The UK Government proposals (outside of Scotland) have proved to be dysfunctional and abhorrent to many of the public. The new Scottish Government has not yet tackled the promised coexistence consultation that is necessary to transcribe the European directive. Evidence from around the world shows that GM contamination of other crops is now a serious problem.
  2. Closely associated with coexistence is the contamination of non-GM food by GM. Although many GM products in food are now labelled, there is a threshold of 0.9 per cent permitted (accidental or "adventitious") GM contamination. There is a fundamental need to lower this threshold to 0.1 per cent, the limit of detection, particularly in relation to organic food (where no GM content is allowed).
  3. Many uses of GM in food and drink processing are still not labelled e.g. enzymes and additives produced using GM.
  4. Produce from animals fed GM feed (see above) is not labelled although it is likely that transgenes will find their way into milk and meat.
  5. The use of GM products by schools and other public services, where in effect the consumer has no choice. (Some local authorities already have a policy on this.)
  6. The question of whether the Food Standards Agency is representing the best interests of the consumer or the industry. There have been several shortcomings apparent, in controlling illegal GM contamination in imports for example.
  7. There is a shortage of manpower to police even the existing standards of food quality. Trading Standards must be given the resources and incentive to ensure that food outlets are following the rules (e.g. in telling customers about any GM content).
  8. Food from the offspring of cloned animals is unregulated at present.
  9. The environmental side effects of growing GM crops have been shown to be significant. No real benefits were demonstrated by the UK Farm Scale Trials (2003), rather the opposite. See 'GM & Environment' above.
Following the above consultation, the Scottish Government's new Food and Drink Policy - "Recipe for Success" - was published in June 2009. There is no reference whatever to GM in the document, although environmental sustainability and healthy food are acknowledged as important throughout. A second consultation "Becoming a Good Food Nation" was launched in June 2014.

A further discussion document "The Future of Scottish Agriculture" was published in June 2015, and "describes a vision for agriculture that will lead the industry to prosper and enhance its performance in supporting our environment, communities and wider economy". Once again, the text is sweeping in style, with no specific mention of GM crops (despite the Government's intent to ban growing them), but broadly summarising key issues that need to be addressed. Comments were invited, from the public and others, until December 2015.

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