A scientist’s appraisal of the public perception of GM food crops in the U.K.

Donald Boulter, Department of Biological Sciences, University of Durham, South Road, Durham DH1 3LE, UK

In spite of a general scientific consensus (apart from a few scientists) that GM food is safe and that, if properly regulated, GM crops pose no greater threat to the environment than conventially bred crops, the UK public have chosen, for the present, to reject GM food.

This paper refers to how this situation came about and to outline how the science of GM crops might have been more clearly put in the public debate. It is aimed primarily at scientists but could also be of use to media "gatekeepers" and regulators.

The situation

The public perceive risk in a wider context than that of strictly scientific risk factors. In the case of GM food, these so-called outrage factors (Boulter, 1995; 1997) have predominated so that scientific evidence has been largely ignored. Of the ten or so outrage factor pairs, e.g. voluntary/non-voluntary, familiarity/non-familiarity etc., the public have in every case, been influenced by the alternative which lowers the acceptable level of risk that is traded off against any benefit (see Boulter 1995) (in this case, for the consumer, direct benefit was perceived to be non-existent). Once public trust is lost in this way through the operation of outrage factors, it is not easily re-gained. Scientists are placed in the invidious position that they can do little to persuade the public since the public now has the view that it is the unforeseeable practical consequences of scientific advance (freely acknowledged by the scientists themselves as being intrinsic to good science) that is the problem and therefore requires a precautionary approach.

The explanation that it was the interplay of outrage factors that led to the present situation in the U.K. only gives a qualitative explanation i.e. not a precise measure by which to predict the outcome of a particular risk/benefit equation. For example, in the U.S. where GM crops are generally acceptable, it would not have been easy to predict the different outcome even when outrage factors can be shown to differ from those in the UK (the regulatory system is more open and trusted, there have not been food scares on the scale of BSE, the public are more up-beat about the benefits of science, and the environment/farm interface is less intimate).

Can scientists learn something?

Undoubtedly disagreement among scientists (e.g. see Ewen and Pusztai, 1999) was a major factor in the rejection of GM food. However, it is inevitable with new science and technology that the scientific community, trained to question the scientific data, will inevitably disagree to some extent with one another. Some might argue that these disagreements should be carried out in the scientific literature rather than in the media, but this is probably a counsel of perfection. Also the details of the competing data are often too esoteric to directly inform public debate.

Since "nothing" can be proved to be 100% safe, scientists sought a base-line starting with the observation that conventional crops/food are generally safe (little evidence to the contrary). Thus many scientists discussed GM food as a comparison between the two systems but often in a limited way. In using comparability as an argument for accepting GM crops, for example, the benefits of high-tech agriculture are assumed to far outweigh its disadvantages, but can this be taken for granted? I therefore present below a wide-ranging comparison, not with the view that such public information would have led to a different outcome (there are many different groups each with their own agenda and constituents) but rather that in a modern democracy, it is the responsibility of scientists to present all the facts in an understandable way to the public; incidentally it may expose the limitations of some of the "sound-bite" arguments that were used.

Comparison between the production of GM and conventionally bred crops


                    GM                                                                                                               CONVENTIONAL

1. Includes a biotechnological step.                                                                             Usually no biotechnological step.


An important difference in the sense that technical/non technical is an outrage factor. However, there is considerable evidence that the type of somaclonal variation induced by the biotechnological tissue culture step in transgene transfer in GM is also seen in conventional crops. Unwanted variation is selected out in the subsequent breeding programme in both GM or conventional crops.

2. Transgene insertion into host genome is                                                                    Genes inserted usually homologously.
semi-random. (i.e. to sites in the genome established during evolution).


The significance of this difference lies in the fact that genes inserted non-homologously may activate or inactivate other genes (pleiotrophic effects). However non-homologous gene insertion also occurs to a lesser extent in conventional crops. Also transposon type ("jumping genes") are present in both GM and conventional crops which also move to new positions in the genome semi-randomly. Thus pleiotrophic effects are well known in both GM and conventional crops and generally comparable.

3. One or a few well characterised transgenes                                                              Many unidentified genes (c1000) are  are used which can be easily monitored in the breeding programme.                                  recombined.


Conventional breeding generates variation in a wide-range of characters much of which is undesirable so that the breeding programme is longer than for GM.

4. Transgenes can cross species barriers.                                                                     Breeding normally involves crossing from                                                                                                                                      within species although wide-crosses
                                                                                                                                   involving different genera is sometimes
                                                                                                                                   Also GM occurs in nature to a limited



A species is defined as an inter-breeding population, i.e. normally genes will not cross species barriers. It is generally accepted that this has arisen in evolution as a means of restricting unregulated promiscuous gene exchange in order to balance change (needed for adaption) with present fitness for the status quo. However, from the large number of gene transfers so far, there is no evidence that breaching this restriction using GM has given rise to any destabilisation of the host genomes or reduction of ‘fitness’. Considering the genes themselves, positively, because of the wide choice of desirable trait genes, highly nutritious, well protected (high productivity) GM crops and foods are more likely to be bred than using conventional methods. Negatively, what do we know about the dangers of transgenes from outside the species. In the seventies in the early days of genetic modification, scientists instituted a GM embargo until the risk of producing "monsters" could be assessed by experiments under extreme containment conditions. These experiments showed no evidence that unforeseen microbe "monsters" could result and therefore GM went ahead globally; all subsequent experience supports this view.

Most of the present and future types of commercial transgenes have equivalent genes in plants, animals and bacteria due to common ancestry in evolution. Each of the equivalent genes will have the same function in different organisms but will encode a protein with a slightly different structure (sequence of amino acids). For example, a bacterial gene introduced into a GM crop to give herbicide tolerance has an endogenous equivalent gene with the same function, but whose different structure is susceptible to the herbicide. Further, similar herbicide tolerant genes occur in the breeding population of the conventional crop. The reason why these are not used is because they are extremely rare and difficult to select in plants but readily selected in bacterial culture. We don’t know precisely how many genes are common in different organisms. For example, 98% of ape genes are common with humans, but the further apart the common ancestor is the percentage drops off; even with humans and bacteria there are a large number of common equivalent genes. Thus whilst the transgene may be "foreign" in that its source was outside the crop species, it is likely that there is an equivalent gene in the crop species and in this sense the gene is not either a bacterial or plant gene, but both. In this light the "foreign" gene appears more benign. Nevertheless some anti-GM groups oppose the use of such transgenes on the grounds that to do so is unnatural. Unnatural because such gene recombination would not normally have occurred in nature, although crossing of species/generic barriers can occur to some extent in nature. Unnatural because a different method of gene transfer from that of evolution has been used, although some GM by this method does occur to a limited extent in nature. What is the argument then that plant reproduction is special and GM should not tamper with it?, after all conventional plant breeding and horticulture do by using artificial pollination and we have and do continuously interfere with nature; life as we know it would be impossible otherwise. The argument comes down therefore to a matter of spiritual belief, i.e. the process of plant reproduction is sacrosanct, God’s province. Others, whilst not necessarily believing in God, hold nature to be sacrosanct. Belief (faith) is the basis for the decision. Nature has been viewed during human history in many different ways, sometimes as a source of purity sometimes of impurity and danger. The terms natural/unnatural are logically impossible to define but have been used to justify many different things, e.g. burning of witches. In considering this issue therefore we will be involving an outrage factor (memorability) and for some unnatural is a dread word. Finally, the burden of proof should be to show how this particular interference is more dangerous than existing practices, not to assert the belief that anything unnatural is worse than any natural thing.

5. High-tech                                                                                                                    Normally high-tech


A small percentage of conventional farming, i.e. organic farming, restricts the use of chemicals but it is not, as is often claimed, chemical free, or uses only natural substances, hence the recent Advertising Standard authority ruling against such claims in a Tesco brochure. Considerable amounts of data on the advantages and disadvantages (short or long term) of the different agriculture systems have been accumulated. Present indications are that high-tech agriculture is highly productive and sustainable, but more information is required in order to make informed decisions about its advantages in some of the many varied situations globally. Some consider that high-tech agriculture (especially GM crops) is bad for the environment (see later) and that low, input systems, e.g. organic farming have not been given due attention either in developed or undeveloped countries.

6. Regulated                                                                                                                    Less regulated


GM crops are more strictly regulated both with regard to food health and possible environmental impacts. Since GM technology is a new method and new technologies sometimes bring increased risk this stricter regulation is required (unless eventually shown to be unnecessary). Conventional crop foods are generally considered by scientists to be safe and the same applies to GM food. Longer term experiments to see if there are any effects on basic functions such as the immune system are needed for both types; the toxic effects of some "things", e.g. tobacco smoking are long term.

7. Affects environment                                                                                                       Affects environment


The question of environmental impact of GM crops is complex and contentious. A great deal (but by no means all) is known about likely impacts from the experience of conventional crops, isolation distances and other managerial practices as well as from many small scale plantings of GM crops (see Boulter, 1995). However, each case can be different and it is difficult to generalise depending on geography, climate, type of GM crop, presence of wild and weedy relatives, etc. and that effects are possible on a wide range of different plants and animals according to if and when they were exposed to GM contamination. Key questions are, will gene escape occur? How frequently and what would be the consequence? The lessons of evolution and agricultural history indicate that some plant genes will escape from GM and other crops into the local ecosystem. The consequences of these escapes may range from nothing to more environmental serious effects depending on particular situations. Once again there exists a large amount of data on the effects in the UK situation of the many variables involved such that the scientific consensus based on existing data is that with present regulations and monitoring, it is not unreasonable to allow field testing on a commercial scale in order to obtain the further data needed before commercial growing is approved in the UK (already possible under E.E.C. ruling). It is conceivable that some prior environmental impact analyses will veto, in particular situations, commercial growing of some GM crops, where for example an endangered species were threatened.

Whilst many will consider it reasonable to go ahead open mindedly and obtain the data needed to enable informed decisions to be made, others, for example Greenpeace have chosen to destroy GM crops, actions now legitimised by the Courts. They argue they are doing it to avoid GM contamination and pollution (highly emotive words) in order to protect their property and livelihood (although psychologists might suggest otherwise). But what is causing the pollution anyway, particular genes/proteins (most natural of compounds) which already occur widely in nature if not necessarily in that particular ecosystem situation.

It is true that certification for organic farming status requires it to be GM free thereby making GM contamination unacceptable, but is this a justifiable argument when an organic farmer may already use unnatural chemicals (see earlier).

Lastly, it has to be appreciated that humans and other animals, particularly fungi and insects compete for food globally from a more or less static amount of food, so with global human population increasing, unless agriculture becomes more productive and losses controlled, inevitably, fewer non-human animals will survive.

8. Less need for exogenous chemical protection                                                                 Greater need for chemical protection                                                                                                                                          (organic food excepted)


Commercial crops need chemical protection as endogenous protectants are insufficient. GM crops have a reduced need for added chemicals relying on endogenous and transgenes for protection against pests, diseases and weeds. So far there is little evidence that the low levels of added chemical residues found in conventional crops are harmful, but if further research on long term effects were established, then the case for GM crops/food is strengthened.

What is the future of GM crops/food in the UK?

Indications are that an open regulatory apparatus will ensure that GM foods will be accepted by the public as safe in the long run. In the end, their future will depend on whether or not they are accepted by the public in the knowledge that some gene escape would be inevitable (as is normal in evolution and farming). Field trials, if they go ahead, would only define the probabilities and extent of risks in specific instances (identified as particularly sensitive), but because of the many different environmental situations it would not be feasible to investigate all possibilities.



Boulter, D. (1995) Phytochemistry, 40, 1.
Boulter, D. (1997) Critical Reviews in Plant Science, 16, 231.
Ewen, S.W.B. (1999) The LANCET, 354, 1353.

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