GM issues | Safety testing made simple - too simple
The mainstay of safety testing of GM
food is, and has always been, compositional analysis. This
involves breaking down the food into components roughly similar to the
assumed products of digestion, and measuring all the main groups of
substances formed. This technique works well for assessing
the quality of animal feed because livestock have a restricted diet and
any deficiency in a major nutrient will lead to ill-health.
For human beings, normally on a much more varied diet, it's not
entirely relevant.
Compositional analysis will also routinely extend to any toxins known
to be associated with the food. Novel, unexpected or unknown
toxins such as might be generated by a GM plant won't be included in
these measurements. The novel ability of the novel life-form
to support pathogens will also not be revealed.
Another routine quality-control test performed on GM-commodity crops,
such as maize and soya, is livestock feed-conversion. Such
trials are a legal necessity prior to marketing of feed to ascertain
its nutritional value, and are often used as the main or only, 'proof'
of safety of a GM crop. However, their relevance to man is
very remote, and since modern farm animals fattened on GM grains are as
a rule slaughtered in youth, they don't live long enough to reveal
chronic effects from their feed.
The only way to be certain that harmful elements are absent from food
is to feed it first to an animal and then to a person under controlled
conditions and watch what happens.
Feeding studies on animals are extremely difficult to perform. Their
scope is severely limited by the natural diet of the test animals, and
the extrapolation to humans is always uncertain. Healthy animals will
be least likely to demonstrate adverse effects, while stressed or aged
animals will be most susceptible. Choice of the strain of
laboratory animal used will affect the data: inbred animals give more
uniform results but may be unusually insensitive to the toxin tested,
outbred mice are always variable, so that low levels of reaction may be
significant. The standard test is a 90-day feeding study on
healthy young rats. This will only be certain of revealing
acute problems.
In practice, the routine GM feeding studies rarely use whole foods but
are restricted to tests using analogue proteins isolated from
non-food substitutes, GM bacteria. In this form,
the test material is conveniently plentiful, easy to feed in standard
amounts to standard laboratory rodents at a standard dose for a
standard period of time. They are, however, irrelevant as a
test for the safety of a variable whole food eaten by variable humans
in variable amounts over variable times. Animals can be
crammed full of the pure GM protein substitute, and if it doesn't kill
them, this becomes an excuse for no further safety-testing of any GM
crop expressing a similar protein, even if the new crop is stacked with
several varieties of novel protein.
Very occasionally, EU regulators will require a 90-day feeding
experiment using whole GM food during which indicators of toxicity are
checked. The 90-day trial was developed to assess the effects
of chemicals such as drugs, and is excellent for picking up the first
symptoms of acute toxicity. It is much less appropriate for
whole foods, because these consist of a complex of interacting
materials able to mask toxic effects in the short-term. It is
entirely inappropriate for investigating chronic health impacts because
the animals' ability to withstand or overcome physiological challenges
(such as, infections or stress) is not any part of it.
What the EU regulators don't require are continuous breeding studies on
populations of laboratory animals fed a GM diet for several
generations. (Note. Multigenerational studies
mentioned in biotech industry applications to market GM refer to
separate feeding trials performed on successive generations of
animals.) This may be a very serious omission, because the
only continuous breeding study carried out using mice fed a Bt-toxin
containing maize(1) and rats fed herbicide-tolerant soya (2)
found seriously reduced survival in successive litters.
A 2007 review of the published papers on feeding studies which examined
signs of toxicity found only 27 covering 18 different GM crops and was
able to summarise them in 1½ pages. (4) Of those
listed, only 9 examined crops which have been commercialised (most of
these nine are described 'Is RR soya safe?). All of the
studies were limited in the scope of parameters recorded, the numbers
of animals and duration of feeding.
In summary, the safety testing of GM food is too brief, uses
inappropriate substitute materials, is based on tests not designed to
be applied to the human condition, and too few of them have been
carried out to publishable standards.
How did we come to get it so wrong? Well, for starters, the
test protocol was designed by Monsanto. (3)
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A. Velimirov et al.(2008), Biological effects of transgenic maize NK603 x MON810 fed in long term reproduction studies in mice, Institut für Ernährung, Forschungsinstitut für bilogischen Landbau, Vienn
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Ermakova I. V. (2009), Influence of soy with the gene EPSPS CP4 on the physiological state and reproductive functions of rats in the first two generations, Russian Academy of Natural Sciences: Modern problems of science and education, 5
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Andrew Cockburn (Monsanto), Assuring the safety of genetically modified (GM) foods: the importance of an holistic, integrative approach, Journal of Biotechnology, Volume 98, Issue1, 11th September 2002
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Domingo J. L. (2007), Toxicity Studies of Genetically Modified Plants: A Review of the Published Literature, Critical Reviews in Food Science and Nutrition 47