Better safety checks needed on GM foods

A Royal Society report calls for more consistent safety checks on GM foods but some think it doesn't go far enough.

Feb 6, 2002
Susan Mayor(

LONDON — Regulatory processes controlling the development and use of genetically modified (GM) plants need to be improved in order to reduce the risk of any adverse effects on human health, a report from the Royal Society has warned.

The report, Genetically modified plants for food use and human health — an update, considered that there was no evidence casting doubt on the safety of the few foods made from GM ingredients currently available, nor to indicate that genetic modification made foods inherently less safe than non-GM counterparts. It called, however, for the tightening of regulations for all novel foods, particularly with respect to allergy testing and the nutritional content of infant formula.

The recommendations were drawn up by a panel of leading UK scientists with expertise in GM foods, with funding from the Royal Society (an independent body that promotes the natural and applied sciences). Their work followed the publication of an earlier report — Genetically modified plants for food use — by the Royal Society in 1998, which called for further consideration of the effects GM foods might have on human health. Panel members considered the results of research made available since 1998, in addition to evidence submitted by food regulators, biotechnology companies and non-governmental organizations. All oral evidence has been posted on the Royal Society website.

The report recommended that the methods for comparing GM foods with their conventional counterparts, by applying the principle of 'substantial equivalence' should be made more explicit and objective during safety assessments. Clare Mills of the Institute of Food Research and member of the Royal Society working group, explained: "At the moment, substantial equivalence is the main approach used to assess the safety of GM ingredients, together with other novel foods. It is based on the assumption that a new GM crop is safe if it is essentially the same as the unmodified equivalent. This is assessed by comparing the agronomic, biochemical, chemical and nutritional parameters of the GM food relative to existing conventionally produced foods." Macronutrients, micronutrients, known toxins and other anti-nutrition factors are also measured. There is no standard list, however, of what components must be analysed for each food.

GM foods are placed in three classes, based on the results of substantial equivalence testing:

The food is considered to be substantially equivalent in all respects and no more information is requested.

The food is considered to be different only in the genetically modified characteristics — for example, the gene products that make the crop resistant to insects or tolerant to a herbicide. In this case, the potential of the new protein is evaluated for any allergic or toxic potential. The novel proteins are tested in isolation, not as part of the whole food. If there are any antibiotic marker genes in the GM crop, these are evaluated to determine if they pose a risk in increasing the development of drug-resistant bacteria.

The food is not considered to be substantially equivalent, so more toxicological and nutritional data are required.

Scientists critical of this approach have previously argued that gross chemical comparisons between GM foods and conventional counterparts are not sufficient to detect unexpected changes that might arise through the process of genetic modification. In a paper published in Nature in 1999, Millstone, Brunner and Mayer, argued that the use of substantial equivalence is a "pseudo-scientific concept because it is a commercial and political judgment masquerading as if it were scientific. It is, moreover, inherently antiscientific because it was created primarily to provide an excuse for not requiring biochemical or toxicological tests. It therefore serves to discourage and inhibit informative scientific inquiry" (Nature 1999, 401:525-526).

The Royal Society working group has now agreed that measurement of subjective equivalence can be subjective. Susan Mayer, one of the authors of the Nature paper that criticized the concept of substantial equivalence and director of Genewatch UK, a not-for-profit policy research group, commented: "We are delighted that the Royal Society report has vindicated our criticisms of substantial equivalence. However, we would depart from the report's comment that despite the problems with testing, all currently available GM foods are safe." She pointed out that this appeared to be based on the absence of reports of adverse effects, but argued that no data on the issue had been collected systematically.

The Royal Society panel has suggested various ways to improve the safety assessment of GM foods. In particular, they recommended the use of new profiling techniques to assess the effects of genetic substitutions in developing plants. Mills explained what these might include: "Techniques in the post-genomic era offer exciting prospects for developing more rigorous ways of implementing substantial equivalence. Metabolomics could be used to profile metabolites." She reported that this is already being used successfully in medicine, and could be used in a similar way in plants. "Proteomics could be used to assess an entire protein profile," she continued. "This would enable us to detect whether a plant differed compared to conventional plants, and would reveal precisely how it differed."

Mayer agreed that more detailed profiling of GM foods offered a better way of testing them. "We need to develop systematic mRNA screening, picking up patterns of changes, including changes in protein profiles. This would provide a finger printing test for each food, triggering when it was necessary to look at a product in more detail." She considered that biological testing was also required. "Chemical changes are not always a guide to biological effects," she pointed out. "We need to develop biological tests, which we would prefer to be based on in vitro techniques."

The Royal Society report has also recommended that allergy screening of all new foodstuffs, regardless of whether they contain GM ingredients, should be extended to include risks from inhalation. At present, tests are only carried out for material that is eaten, but the report warned that there were potential risks of allergic reactions from breathing in pollen, spores and dust. The report also advised that UK and EU laws should be re-examined to ensure that rigorous tests should be required if GM ingredients were considered for use in infant formula.

Finally, the Royal Society panel members were concerned that safety assessments differed in different countries and suggested that they should be harmonized between member states of the EU. They welcomed the development of consensus documents by the OECD for different crops so that the principle of substantial equivalence could be applied uniformly.

Jim Smith, who chaired the working group that produced the report, said: "The rather piecemeal approach to the regulation of GM foods in the UK, and the EU in general, means that there may be some important gaps and inconsistencies. It is obvious that consumers want their food to be safeguarded by rules that are rigorous enough to prevent any loopholes." But he concluded: "The legislation must not be so restrictive that it removes any incentive for introducing new food products that are potentially beneficial to society."