Seeking clarity in the debate over the safety of GM foods

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Millstone et al. reply

Our Commentary1 on the use of the concept of substantial equivalence in evaluating the safety of GM foods has triggered a lively debate, but several correspondents have criticized us for things that we did not say, and in our view none of them has addressed our central argument that using substantial equivalence discourages vital scientific investigation.

Trewavas and Leaver2 and M. J. Gasson4 have suggested that we argued for full toxicity testing of all novel crop seeds in all potential circumstances of use. We did not make that assertion, but rather looked askance at an approval system that, if measured against the yardsticks of scientific rigour and public confidence, we believe is not adequate or effective. We also sought to unravel some of the reasons why confidence is lacking, and suggested ways in which the approvals system might be strengthened.

We do not agree with the view that single-gene changes necessarily result in well-characterized plant responses. For example, experimental genetic manipulation of oilseed crops, including rape, has led to the unexpected discovery of enzymes and regulatory mechanisms affecting lipid metabolism. Gasson's confidence that unexpected alterations in crop chemistry as a result of genetic modification are unlikely is contradicted by a report5 at a recent meeting that glyphosate tolerance in Roundup Ready soya beans appeared to be occurring at the expense of diminished heat tolerance as a result of changes to the lignin content. That research was triggered by the unexpectedly poor performance of Roundup Ready soya bean in hot climates, and it was only biological testing under various conditions that revealed the effect.

We totally reject the accusations made by Derek Burke6. Our Commentary contained no conspiracy allegation, nor did we criticize any individual — merely ‘wishful thinking’. There seems to be an unwillingness on the part of some enthusiasts for GM foods to engage with scientific challenges and policy questions such as those we posed. We are not demanding exhaustive toxicity tests. Rather, we hope to encourage a re-examination of what constitutes an adequate risk assessment for GM and other novel foods. This might help to improve public acceptance of the technology.


  1. 1

    Millstone, E., Brunner, E. & Mayer, S. Nature 401, 525– 526 (1999).

  2. 2

    Trewavas, A. & Leaver, C.J. Nature 401, 640 (1999).

  3. 3

    Food & Agriculture Organization/World Health Organization Biotechnology and Food Safety: Report of a Joint FAO/WHO Consultation (FAO, Rome, 1997).

  4. 4

    Gasson, M.J. Nature 402, 229 (1999).

  5. 5

    Getz, J. M., Venecil, W. K. & Hill, N.S. The 1999 Brighton Conference 8C-6, 835–840 (British Crop Protection Council, Farnham, 1999).

  6. 6

    Burke, D. Nature 401, 640–641 (1999).

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Millstone, E., Brunner, E. & Mayer, S. Seeking clarity in the debate over the safety of GM foods. Nature 402, 575–576 (1999) doi:10.1038/45058-c1

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