Many countries, particularly Japan and most of the European Union, have become extremely polarised on the issue of GM foods, to the extent that it is becoming difficult for any food manufacturer wishing to supply those markets to knowingly use GM ingredients.
One might think this would not create any especial problem for food suppliers since currently only two food crops are widely commercialised as GM varieties and by no means every farmer or country is using them. Unfortunately the sheer scale of production of the two crops concerned, soya and maize, combined with the nature of GM technology (which makes it hard to segregate but easy to detect) and an unparalleled scrutiny by activists and the media who refuse to accept even trace contamination, will make it difficult and expensive to ensure GM-free products, and this situation will continue for some years until a reliable non-GMO supply chain is established.
Looking at these factors in detail, the United States, the world’s biggest producer of soya and maize, has to date considered genetic modification for herbicide or pesticide resistance to be a production technology with no implications for crop quality, food value or health. Its regulators therefore permit GM and non-GM varieties to freely intermingle through the long bulk supply chain (in the same way that crops sprayed with different types of approved pesticide or herbicide are allowed to intermingle). That said, increased awareness of environmental and health concerns has recently prompted the US Secretary of Agriculture, Dan Glickman,to demand more research which could, if ecologists’ fears are proved, lead to some rolling-back of commodity GM crops.
For the time being however, unless otherwise proved, any soya or maize from the US must be assumed to be partly GM,and certainly contaminated to a degree unacceptable to European consumers.
Until recently the alternatives to GM soya and maize have been certified organic, since organic farmers, even in the US, do not permit the use of GMOs, and identity-preserved (IP), whereby buyers contract with individual farmers ahead of planting to separately grow, harvest, bag and ship a particular (usually non-GM) variety. In theory both organic and IP should be reliably GM-free and certainly no more than trace contaminated.
IP and organic are traditionally small-scale operations designed to provide food quality supplies such as soy for Japan. The vast bulk of soya and maize is grown for animal feed and industrial applications where less stringent standards apply. However, there is a rapidly increasing demand for GM-free oils and lecithin (a by-product of soya oil production). Economic processing of these products requires big volumes and needs the involvement of the big players such as Cargill and ADM. There are now strong signs that this will happen. For example ADM has offered a premium to farmers growing a soya variety, Synchrony, which -while being herbicide resistant- has not been genetically modified.
This year as much as 12 million acres of Synchrony will be planted and the oil and lecithin processors are gearing up to produce non-GMO products from this source. Whether it will be possible in this growing season to offer the “< 0.1% GMO” demanded by some retailers and manufacturers remains to be seen.
The only other bulk commodity sources of non-GM material come from countries that do not or will not grow GM crops. This includes areas such as parts of Brazil and Canada for soya and Canada for maize. These countries can produce quantities sufficient to achieve bulk economies of scale and at a reasonable price.
However this approach is not without its problems. Take Brazil. Despite a series of legal obstructions from activists, the government there has just legalised the growing of GM soya which will make non-GM areas voluntary. Farmers will be opting to grow a more costly crop (the greater cost of GM seed is usually more than offset by less use of expensive herbicide) in the hope of getting a commensurately higher price later.
But with an open border to Argentina, which already grows large quantities of GM soya, the temptation to covertly mix varieties will be great. Indeed, GM soya is known to have been illegally cultivated in parts of Brazil for some time. To counter this, non-GMO areas like Rio Grande du Sol in Brazil are embarking on rigorous testing programmes to try to ensure the purity of their product.
Growing and exporting two product streams that are essentially identical means that there are massive opportunities for accidental or deliberate cross-contamination. Consequently, the accreditation of the supply chain is of paramount importance, but as the recent experience of Tesco with its non-GM pizza which tested GM-positive shows, accreditation risks being flawed unless it is backed by rigorous testing.
The problem is that the same technology that enables food producers to screen for GM contamination also allows activists and hostile media to check many finished food products. In this way GM contamination may be likened to pesticide residues, except that no regulatory authority has set permitted maximum levels of GM contamination (hardly surprising – GMOs are not supposed to be harmful!). To the food industry’s critics, any amount of contamination is bad, even to the level of one stray gene in a pizza, never mind that scientifically and medically such findings are meaningless.
A number of companies are now offering test-supported accreditation services for non-GMO material similar to that used by organic producers. This gives a seal of approval which can be recognised by retailers and quoted to reassure consumers. It is difficult for Europeans to visualise the sheer scale of the farming and processing of soya and maize in the USA. The area planted under soya alone would be sufficient to cover the whole of the UK. From the farm to the processor requires as many as 7 stages of transportation at each of which there is the potential for cross contamination. The whole process is geared for maximum efficiency and the transport volumes rapidly become huge (30 – 100,000 tonnes per load). This is how these commodities have kept their prices low while maintaining some margins along the chain. The challenge is to have reliable accreditation without putting an unbearable cost burden on the commodity.
Sampling plans for each point in the chain have been worked out for a number of parameters by organisations such as the USDA and these can form a generally recognised basis for statistically valid sampling. The next issue is to define analytical methods, and which of them are appropriate for each stage in terms of speed, cost and ease of use.
Currently there are two methods for determining whether a genetic modification is present. One looks directly for the modified gene, the other for the effect of the genetic modification.
Table 1 – Comparison of different testing technologies
|Cost / sample||£5-10||£10-30||£100-200||£150-300|
|Quantitation||Semi Quant||Quant||Semi Quant||Quant|
|Skill level required||Low||Moderate||High||High|
|Cost to set up||V.Low||Moderate||High||High|
|Speed||<30 mins||4 Hours||Day||Day|
|Applicability||Limited to Raw Materials||To all but highly refined products|
Genetic modification entails either a specific modification of an existing gene or the introduction of a specific sequence of “foreign”DNA.The tomato produced by Zeneca with improved ripening characteristics and used in the manufacture of tomato concentrate has had one of its genes switched off. Monsanto’s Roundup Ready® soya has had a gene introduced from another plant variety, which confers increased resistance to the herbicide glyphosate.
In both cases it is not the gene which is directly responsible for the effect of the modification but the presence of the protein (or its absence in the case of the Zeneca tomato) coded for by the gene.
Where a specific novel protein is expressed, as in Roundup Ready® soya, it is possible to use a technique known as immunoassay to measure the levels of this protein in a sample. Currently immunoassay systems are available for RR soya and will soon be available for the Bt and Liberty Link maize varieties licensed for import into the European Union. This system is available in two formats. The first format is a qualitative strip test analogous to the home pregnancy test, which will give a positive answer if the protein is present in the sample above a threshold concentration. The second is a quantitative test for determining exact levels of protein in compounded material.
The immunoassay technique is a rapid and cost-effective method for determining the extent of GM contamination in the field, at different transportation points and during primary processing (e.g. to flour or starch). It is ideal for supporting accreditation because it is easy to perform and is suitable for both field and Lab use. However as processing continues the protein becomes denatured and the correlation between protein and GM contamination breaks down. At this point immunoassay techniques become unreliable and it is necessary to look for the changed gene itself.
DNA is broken down readily during processing into fragments but if these fragments contain DNA sequences unique to the genetic modification being sought, the
Table 2 – Applicability of testing methods to various soya products
|Full Fat Flour||Yes||Yes|
DNA can still be reliably detected. Detection and amplification of DNA fragments is provided by a process known as PCR (Polymerase Chain Reaction). Because PCR is able to detect modified DNA through most levels of processing to the final product, it is currently the method of choice to determine whether manufacturers’ claims about GM-free products are true.
Although PCR is very sensitive, it is not highly quantitative, particularly in finished products which may contain only a small portion of the possibly GM ingredient such as soya. This leads to testing for a “de-minimis” level of contamination which -arguably- it is doubtful that any food product could “pass” if GM crops become more widely grown.
Techniques that improve the quantification of DNA by PCR are becoming available and as the technology matures there is a rapidly improving standardisation to ensure comparability of results. Because of this, PCR will remain for the foreseeable future the method for QC of finished products and for regulatory enforcement.
However, PCR techniques are highly specialised and require a significant investment in people, space and equipment to set up. This means that the technology will remain expensive, even if carried out in-house.
Neither immunoassay or PCR can tackle ingredients which have been transformed so much by processing that there is no longer any detectable DNA or protein to measure. These include refined oils, some lecithins and of course meat from animals reared on GM feedstuffs. There is currently no analytical method available to test whether these might be derived from a GM source.
It is these types of ingredients that are likely to be the biggest problem area for food manufacturers and retailers. The only realistic solution is certification supported by testing performed before the source material is significantly processed or consumed by livestock.
In fact, this advice applies to all GM-free/non-GMO ingredients. Contamination is always a risk and it is doubtful whether activist groups or consumers will accept a defence of ignorance, especially if the paper trail leads to sources which are known to be unreliable. By using techniques such as immunoassay to measure the effects of the genetic modification at the early stages of the processing chain, one can ensure that primary ingredients are not contaminated before they enter the processing line. This reduces the need for QC testing by more expensive PCR techniques.