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Safety of food derived from biotechnology

In March of this year the Codex Alimentarius Commission will hold an Ad Hoc Intergovernmental Task Force on Food Derived from Biotechnology. One item on the agenda is a review of the work done or being done by other international organizations in the evaluation of safety and nutritional aspects of such foods. The international organizations include the Food and Agriculture Organization (FAO) of the United Nations, World Health Organization (WHO) and the Organization for Economic Cooperation and Development (OECD).

This is an encouraging move as the public debate on genetically modified (GM) foods is showing depressing signs of following a similar path to that which occurred with irradiated foods. A major difference is that irradiated foods were, and are, never likely to form a major part of the diet in any country, whereas the same may not be the case with some GM foods.

While there are a number of issues being addressed in the GM foods debate, the issue uppermost in the minds of consumers is: are they safe? This is the same question that dominated the public consciousness with regard to irradiated foods. Opponents of the irradiation of foods became expert at citing any published work which showed possible adverse effects of feeding irradiated foods to experimental animals or, in one notable case, to humans.

Public health authorities were accused of ignoring any report of this nature but accepting reports which showed that foods irradiated under controlled conditions produced no toxicological effects in experimental animals.

The reasons for this apparent conflict were straightforward. The design and methodology used in many experiments was flawed and the results could not be reproduced when the design and/or methodology was improved and the experiment repeated. The reproducibility of results is the cornerstone of the scientific method.

Amongst problems noted in animal feeding trials with irradiated foods were dietary deficiencies, restricted food intakes, unpalatable diet, inadequate control diet, too few animals included in trial, and inadequate histopathology. (D.Hattan in Food Safety Evaluation. OECD, 1996.)

In this context, the media coverage of the publication of the controversial study on an experimental line of GM potatoes containing an introduced lectin (The Lancet 354 1999, 1353-54) left much to be desired. It was reported (Sydney Morning Herald, 16 October 1999) that the authors, Ewen and Pusztai, concluded from their work that "diets containing genetically modified potatoes "[have] variable effects on the rat gastrointestinal tract" with the implication they could promote cancer growth. The authors made other claims which were not reported.

No mention was made in the media of the commentary by Kuiper and others (The Lancet 354 1999 1315-16) which accompanied the paper by Ewen and Pusztai and which concluded "the experiments done by Ewen and Pusztai were incomplete, included too few animals per diet group, and lacked controls such as a standard rodent diet containing about 15% protein as a balanced source of amino acids – therefore the results are difficult to interpret and do not allow the conclusion that the genetic modification of potatoes accounts for adverse effects in animals."

In other words, the reported study showed a number of the same flaws which ultimately caused many of the studies on irradiated food to be rejected as not contributing to the evaluation of the safety of those foods.

This passed without comment in the media as did the publication in a subsequent issue of the journal (The Lancet 354 1999 1725-28) of three letters criticizing the methodology of the Ewen and Pusztai work and the authors' lengthy reply.

In the same issue of the journal there were two more letters commenting on the conclusions of the other research report, also on lectins and GM foods, reported in the issue of The Lancet carrying the Ewen and Pusztai paper. This report, by Fenton and others, (The Lancet 354 1999 1354-55), which also found its way into the media, provided data to indicate strong binding of plant lectins to human white blood cells in a laboratory situation. (Lectins from different species of plants may be useful in protecting food plants from insect attack and are a research area in genetic modification of food crops.) Both letter writers point out that the report adds nothing to existing knowledge on lectins and does not provide new reasons to question the safety of transgenic crops.

The commentary by Kuiper and others referred to above is titled, Adequacy of methods for testing the safety of genetically modified foods. Their conclusion is that methods to assess the safety of GM foods that are already on the market are adequate.

Genetic modifcation of food to permit changes in agricultural practice, e.g. herbicide resistance, have involved single gene traits.

However Kuiper and his colleagues point out that the future generation of GM foods, e.g. those involving change in nutritional status, will need a wide range of tests covering both toxicological and nutritional end points. The studies must be designed carefully because of the complexity of whole foods and the lack of sensitivity of animal feeding studies involving them.

It is to be hoped that the Codex Task Force can add to recommendations made by earlier consultancies (OECD 1993, FAO/WHO 1996) on the safety evaluation of GM foods. It would alleviate unnecessary public concern if regulatory authorities were to disseminate their deliberations on applications for permission to market GM foods more widely. It would be expensive, onerous and wasteful for Australia to conduct all its own toxicological testing in this area as suggested by some observers. However the public is entitled to know on what basis experimental studies on the safety of GM foods are accepted or rejected and how relevant these studies are.

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Prepared by Keith Richardson and Beverley George
Food Science Australia
PO Box 52, North Ryde 1670. Tel +61 2 9490 8397 Fax +61 2 9490 8499
Email enquiries@csiro.au