The trouble with genetically modified food


Genetically modified (GM) food has been controversial since the first GM tomato went on sale in the USA in 1994 (1). The GM debate has revolved around: (a) concerns for safety to both human health and the environment; (b) the risk of unintentional spread of the transferred gene to non-GM plants; and (c) the concern that a few large GM seed-producing companies will gain control over our food supply.

A landmark case in Western Australia in which an organic farmer is suing his GM canola-producing neighbour for damages is attracting worldwide attention. Steve Marsh is seeking compensation for damages resulting from GM contamination of his organic farm.  Because the organic certifier of Steve Marsh’s farm, the National Association for Sustainable Agriculture Australia, NASAA, has zero tolerance for GM plants, their presence was sufficient for 70% of the farm to lose its certification, and for Steve Marsh to lose his way of life and income.

The case is currently before the Supreme Court, with a decision expected by the Judge within a few weeks. This action is seen by many as a test case that will determine whether or not we will maintain the right not to grow or consume GM foods.

The Defence maintains that Steve Marsh’s neighbour, Michael Baxter, was not negligent in planting his GM crop on land adjacent to his neighbour’s certified organic land, even though he was warned by Steve Marsh that contamination could occur and might result in loss of certification. When Michael Baxter took the step of swathing his crop, a method in which the crop is cut and left to dry for some days before harvesting, the potential for contamination by blowing seed onto the farm was significantly increased. The defence claims that zero contamination by GM was unreasonable and contamination inevitable, and that the organic certifier, not the farmer, was to blame for the loss of certification.

Currently in Australia, the only way to avoid eating GM-derived food is to eat a 100% certified organic diet. Not many people are aware that in Australia conventional foods may contain up to 0.9% GM protein or DNA without being labelled as such (2). Oils derived from GM crops, like canola, do not require GM labelling, since very little GM protein or DNA survive processing. Likewise, dairy products, meat, and eggs from animals raised on GM foods, and honey from bees feeding on pollen from GM plants, do not require GM labelling.

Because Australian food authorities have taken this stance, consumers cannot be certain their food is GM-free, unless they choose to eat a certified organic diet.  Interestingly, the consumer can make an ethical or health choice to purchase free range eggs, chicken, and pork, but this choice is not available with respect to the GM origin of our food.

If Steve Marsh loses this case, he and other organic farmers who lose their organic certification as a result of GM contamination would not be entitled to compensation.  Organic farming could well become unviable, as loss of certification invariably also means loss of income. Additionally, there will be pressure to alter the organic standard to allow the presence of 0.9% GM in organic foods, a tolerance level that is permitted in the EU for unintentional contamination of organic foods. If that happens, there will be no means of purchasing food in Australia that is not potentially contaminated with GM products.

GM food has now been approved to be grown in many countries worldwide. The ubiquity of GM food and its general acceptance by authorities might tend to make the average consumer feel secure about its safety, and to consider the ‘fuss’ being made about GM food as an overreaction by food extremists.

It’s true that GM technology has revolutionised our world in many areas, creating great advances in the biomedical sciences, and has much potential in solving some of the energy and pollution problems the world is currently facing. As far as food is concerned, it is argued that introducing new traits to food crops could potentially enhance the world’s food security. However, it is also important to have a clear understanding of the potential for harm from consuming GM food and engaging in GM farming.   For this reason, it’s worth looking at why a growing number of scientists are dissatisfied with safety claims for GM foods, and to look at broader concerns about GM agriculture and its effect on the environment.

Is GM food safe to eat?

It is stated in Wikipedia’s article on GM food that ‘There is broad scientific consensus that food on the market derived from GM crops poses no greater risk than conventional food’ (3) . However, not all scientists agree, as seen in the December 2013 statement by the European Network of Scientists for Social and Environmental Responsibility (4):

‘As scientists, physicians, academics, and experts from disciplines relevant to the scientific, legal, social and safety assessment aspects of genetically modified organisms (GMOs), we strongly reject claims by GM seed developers and some scientists, commentators, and journalists that there is a “scientific consensus” on GMO safety and that the debate on this topic is “over”.’

The statement also cites a review of animal feeding studies that found there was an equal number of studies that found GM food to be safe as the number of studies that raised serious safety concerns.  In the review, most of the studies that claimed GM safety were performed by the GM companies or their associates. The statement then outlined 7 different areas in which there is scientific dispute about the safety of GM crops in food and on the environment.

A 2004 report from the British Medical Association (5) concluded that ‘… many unanswered questions remain, particularly with regard to the potential long-term impact of GM foods on human health and on the environment. The few robust studies that have looked for health effects have been short-term and specific. There is a lack of evidence-based research with regard to medium and long-term effects on health and the environment.’

Despite these concerns, by 2012 GM crops were approved for use in 28 countries (6), including Australia, where the first GM crops were grown in 2008.

How is GM food safety testing carried out?

The safety of GM food is based on ‘substantial equivalence’, which is defined by the Food and Agriculture Organisation as embodying ‘… the concept that if a new food or food component is found to be substantially equivalent to an existing food or food component, it can be treated in the same manner with respect to safety (i.e. the food or food component can be concluded to be as safe as the conventional food or food component’. (7)

Genetically modified plants have genes inserted into their DNA that code for production of a protein perceived to be of benefit. The types of genes include those for herbicide resistance, like that present in Roundup Ready Canola (originally isolated from the bacterium Agrobacterium strain CP4); those that encode for insecticides, like the Bt toxin sourced from a naturally occurring insecticide Cry1Ab produced by the bacterium Bacillus thuringienesis; and those that encode for particular nutrients, like golden rice, which produces beta-carotene, the precursor of vitamin A.

It is important to note that the new protein produced is often taken from micro-organisms and not from plants, and is, therefore, often new to the human diet (20). Introducing a new gene into a plant could have unforeseen side effects following consumption by humans or livestock: the new gene could interact with other genes in the plant itself and alter plant metabolism and the nutritional and endogenous toxin content of a plant; the new protein could cause allergic responses following consumption, even if in only a subset of the population; and finally, the new protein could itself be toxic to humans or animals either directly, or through interactions with other components in the alimentary tract.

Despite the potential for rather complex and subtle effects on the metabolism of the consumer of these often novel proteins, substantial equivalence is determined by chemical testing, and not by studies involving feeding to laboratory animals or humans. Regulators who decide whether a new GM crop is safe for release into the food chain determine whether the food is substantially equivalent to its non-GM counterpart by comparing, for example, levels of carbohydrate, proteins and vitamins. They also examine the genetic modification, its protein products, and determine the likelihood of untoward effects such as allergenicity or toxicity (8).

When chemical testing shows cause for concern, animal feeding trials may be conducted, but these are generally only short term. They are often conducted for periods as short as 4 weeks, rarely for as long as 90 days.  Trials carried out over such short time periods as these would be unlikely to demonstrate long-term effects like chronic diseases or cancer.

Further, data on safety of a GM food is generated by the food manufacturer, and is not carried out independently by the regulating authority (9), which simply examines the presented data. The fact that GM companies carry out their own safety assessment studies is one of the reasons there is currently a lack of trust in the results of safety analysis of GM foods. In 2012, the American Medical Association made a call for mandatory testing of GMO foods before Food & Drug Authority (FDA) approval (23) - to date this has not been implemented.

Because the safety requirement for GM foods is based on the principle of substantial equivalence, GM foods are not tested on humans for safety before they are released into the food chain.  As a result, studies have never been carried out on human populations to determine whether there are any health effects associated with GM food consumption.

A review of the scientific literature in 2011 found that although there had been a substantial increase in the number of food safety studies since 2006, most were conducted by the biotechnology companies responsible for commercialising the GM plants (21). Another 2011 study looked at the independence of research in the area of GM food safety testing, and found a significant correlation between author affiliation to industry and study outcome that cast GM products in a favourable light (22).

Some scientists are concerned that it would be difficult to detect any increases in allergies or diseases that might be linked to GM foods, since there are no systems in place to track the long term effects on humans of consumption of GM foods. For example, in an article published in Nature (10), Ben Miflin, a proponent of the benefits of GM crops, stated that under current monitoring conditions, any unanticipated health impact of GM foods would need to be a ‘monumental disaster’ to be detected. In the same article, Susan Wuerthele, a risk assessor at the US Environmental Protection Agency, stated: ‘It took us 60 years to realise that DDT might have oestrogenic activities and affect humans, but we are now being asked to believe that everything is OK with GM foods because we haven’t seen any dead bodies yet.’ And David Suzuki, geneticist and environmentalist, stated (31) 'We are now unwittingly part of a massive experiment. Over years, as thousands and thousands of people consume this, we will provide the data which will allow us ultimately conclude whether or not there's any danger.'

Are there any known detrimental effects of GM crops on the environment?

There are 2 main classes of GM crops with potential environmental impacts:

1)      those that confer resistance of the GM crop to a herbicide, which allows the crop to be sprayed with that herbicide without detrimental effect. In theory, such crops should require overall reduced herbicide use in order to control weeds.   Examples include GM crops that are resistant to the herbicides Roundup, or Bromoxynil; and

2)      those that are encoded to produce an insecticide that kills target insect pests when they attack the crop, including the Bt toxin (described above).

For simplicity, we will limit the discussion to studies on the effects of Roundup resistant GM crops in the USA, where Roundup-resistant GM crops are widespread.  A 2012 report showed that herbicide-resistant GM crops had led to a 239 million kg increase in the use of herbicides in the USA between 1996-2011, rather than the decrease that was intended when the crops were introduced (11).

In addition, there has been a rapid development and spread of Roundup resistant weeds because of the intense selection pressure applied by extensive and repeated use of the single herbicide Roundup (11, 13). The weed resistance issue is one of grave concern to agriculture. Weed resistance to herbicides requires farmers to use increasingly higher herbicide application rates, apply additional types of herbicides, and use manual weeding techniques - all of which increase costs to the farmer and herbicide load in the environment. The GM seed companies are responding to the resistance problem by developing new multiple herbicide-resistant strains, which will result in application of additional quantities and varieties of herbicide (11).

Some scientists express concern about the effects on human health of increased use of Roundup in our environment, and the higher residue levels in our Roundup-sprayed food (13).  Roundup has been found to be toxic to human embryonic and placental cells (24, 25) and human cell lines in tissue culture (26) and disrupts the synthesis of oestrogen in human lines (26), even at concentrations lower than the dose recommended for use in agriculture (24, 26).  Evidence that Roundup may be toxic to a range of mammals was evidenced by a study in which mouse bone marrow cells showed DNA abnormalities in the form of chromosome aberrations and micronuclei following exposure to Roundup (17).  

Finally, these widespread herbicide-resistant monocultures support fewer bird and insect species, which has significant and long-term detrimental effects on our ecology (15); Roundup is toxic to some types of phytoplankton, with potentially damaging impacts on the micro-ecology of freshwater systems (18) and has been shown to have a detrimental effect on tadpole populations (19). Roundup has also been found to cause DNA damage to the red blood cells of goldfish(16). Worryingly, a 2012 study examined the frequency of the presence of glyphosate, the active ingredient in Roundup, in agricultural areas of Mississippi and Iowa. Glyphosate was detected in 60-100% of samples of air and rain collected (12).

Don’t we need to use GM crops to ensure the food security of the planet?

It is often argued that GM technology should be embraced, since it provides the technology needed for crops to adapt to the expected harsher environmental conditions in the future. It is also argued that poorer countries that suffer from food shortages would achieve greater crop yields if they had access to GM technology.

However, not all experts agree that planting more GM crops is the best way to increase the planet’s food production efficiency. A report commissioned by the World Bank and the United Nations and carried out by over 400 scientists concluded that GM crops were not the solution to world hunger (28). The report pointed out that yields of GM crops were “highly variable”, providing “yield gains in some places and yield declines in others”.  The report also called for cooperation between scientists and farmers to build culturally acceptable and sustainable food production systems, including:

‘- Low-input, energy-saving practices that preserve and build soil, conserve water, and enhance natural pest resistance and resilience in crops

- Innovative farming methods that minimize or eliminate costly chemical pesticides and fertilizers

- Use of thousands of traditional varieties of major food crops which are naturally adapted to stresses such as drought, heat, harsh weather conditions, flooding, salinity, poor soil, and pests and diseases

- Programmes that enable farmers to cooperatively preserve and improve traditional seeds

- Use of existing crops and their wild relatives in traditional breeding programmes to develop varieties with useful traits

-  Use of safe techniques of modern biotechnology, such as marker assisted selection (MAS) to speed up traditional breeding. Unlike GM technology, MAS can produce new varieties of crops with valuable genetically complex properties such as enhanced nutrition, taste, high yield, resistance to pests and diseases, and tolerance to drought, heat, salinity, and flooding.’

Moreover, a number of studies in developing countries have found that small farms are more efficient than large ones by producing more food per unit area (29, 30).

This independent assessment of how the world should address food security (28) is in direct contrast to the approach advocated by GM proponents. Genetically modified seed is genetically uniform and cannot possibly be suited to the many different microclimates found even within one country. Farming using GM technology promotes a system of monoculture farming that favours one or more genetically engineered traits across the whole crop, at the expense of locally adapted strains that may have inherent and unpredictable adaptations to local environments, pests and diseases.  The resources that might otherwise have been spent to build resilience in crops using systems that build soil fertility and improve water, pest and disease management, are sacrificed for the purchase of agrichemicals, such as Roundup, associated with the GM trait. And finally, farmer independence is compromised by the need to purchase seed for each annual crop – saving GM seed to plant the following year means risking prosecution for patent infringement by the GM seed supplier.

Once again, David Suzuki has something to say on the topic (31): 'More than half the products of, say of Monsanto, are seeds that are generated, not to produce more nourishment or to be better tasting, but to allow these plants to be drenched with Monsanto's pesticides...So it's a business has nothing to do with improving the quality of life on earth.'

What is riding on the Judge’s decision?

The outcome of this case will determine the rights of farmers to produce crops that are free of GM contamination, and of the public to consume GM-free food. If it can be successfully argued that contamination of non-GM land is ‘inevitable’ and that zero tolerance to contamination ‘unachievable’, our right to farm and consume GM-free food may be lost forever.

As we have seen, not all scientists are satisfied with the safety of GM food in the human diet, or the safety to human health of eating herbicide-sprayed food. GM farming has led to spread of herbicide resistance, resulting in increased use of herbicide sprays - not less, and has resulted in variable yields - not the consistently higher yields that were promised.  Further, independent studies conclude that GM farming is not the best way to tackle the problem of food security - not what the GM companies would have us believe.

Once again, David Suzuki (31): 'There's a tremendous amount of money...invested in biotech companies now, and so there's a tremendous amount of pressure to realise some kind of income on that investment...So it's money that's driving it.'

What I'd like to know is - what does GM technology have going for it?


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  30. David Suzuki speaks out against genetically modified food.