BBC: Genetic food raises health fears
Friday, February 12, 1999 Published at 14:01 GMT
The threat to health posed by genetically modified food
is one of the great unanswered questions of science.
High powered technological advances mean that new
types of genetically modified food are being developed
almost daily. It is estimated that 60% of processed
foods now contain genetically modified foods, such as
soya.
As yet there is no evidence that these foods have an
impact on human health.
But fears have been raised by research such as that
controversially carried out by Dr Arpad Puztai, who found
that rats fed on genetically modified potatoes suffered a
weakened immune system and damage to vital organs.
This includes an enlarged stomach wall and a shrunken
brain.
Some scientists believe that tinkering with the natural
genetic structure of food is bound to have a damaging
impact on health, which might only become clear in the
longer term.
Unpredictable nature
Dr Mae-Wan Ho, of the
Biology Department, Open
University, warns that
because no gene ever
functions in isolation, there
will almost always be
unexpected and unintended
"side-effects" from the gene
or genes transferred into an
organism.
She said many new genes
that are inserted into food stuffs are taken from
disease-causing virsues - genetic parasites that have the
ability to invade cells and insert themselves into the
cell's genetic make-up.
As such they have the potential to cause genetic
damage and unpredictable physiological and
biochemical effects.
There is also the potential that the exchange of genes
could lead to the creation of brand new disease-causing
organisms, made up of genetic material from many
different species.
Dr Ho said: "We simply do not have sufficient
understanding of the principles of physiological
regulation to enable us to categorize those genetic
modifications that will pose a risk and those that do not."
The unpredictability of genetic modifications has been
illustrated by an experiment on yeast which was
genetically engineered to produce hgher levels of
enzymes to break down sugar.
Boosting the enzyme levels, however, led to the build-up
of a toxic compound called methyl glyoxal.
Increased antibiotic resistance
Many scientists are concerned about the use of
antibiotic-resistant "marker" genes in genetically
engineered crops.
They fear that exposure to these genes will eventually
lead to the development of antibiotic resistance in the
bacteria found in the intestine of animals - or humans -
who eat the crops.
In turn many micro-organisms may build up antibiotic
resistance, and antibiotics may eventually lose their
ability to combat disease.
Serious concerns have already been raised over a
genetically modified maize produced by the Swiss firm
Novartis.
The maize contains a gene which can generate
resistance to antibiotics, and which the UK
Government's Advisory Committee on Novel Foods and
Processes has warned could rapidly neutralise medicine
such as penicillin.
Allergic response
Genetically engineered food also has the potential to
give rise to new allergens.
Scientists fear that many of these will not be detected
before wholesale release into the food chain because
no-one can say what to test for.
A transgenic soybean containing a brazil-nut gene has
already been found to be allergenic, as has a transgenic
yeast engineered for increased rate of fermentation.
Dr Vyvyan Howard, a foetal and infant toxico-pathologist
from the University of Liverpool, said genetically modified
foods would have to be treated and tested like
pharmaceutical drugs.
He said: "We are going to have to treat these plants like
pharmaceutical agents.
"We consume food in a lifetime in tonnes, whereas with
a drug you would expect to take it for a couple of days in
milligrammes."
Dr Ian Taylor, scientific political adviser for the
environmental charity Greenpeace, said his organisation
had serious concerns about the potential health impact
of genetically modified products.
He said: "There is a huge domain of scientific
uncertainty about the impact of these things.
"The medium or long-term effects of introducing
genetically engineered organisms into the environment or
the food chain are unknown and unpredictable.
"No-one is even able to ask the questions about what
the impact will be of introducing genes never before part
of the human diet."
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