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9-Misc: UK GM debate (1): GM - The Truth



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TITLE:  GM - the truth
SOURCE: The Guardian, UK, by Ian Sample
        http://www.guardian.co.uk/gmdebate/Story/0,2763,1002374,00.html
DATE:   Jul 21, 2003

------------------- archive: http://www.genet-info.org/ -------------------


GM - the truth

Today the government publishes a report which will have a major impact on
whether Britain becomes a GM nation. Ian Sample asks the vital questions
- and weighs the scientific evidence

For the past eight months, two dozen scientists have had their heads
down, pondering over piles of scientific papers, in the hope of answering
a simple question: what will happen if the government gives the green
light to genetically modified crops? Today, the government is due to
publish its conclusions. Amid hundreds of pages littered with ifs, buts
and maybes, the report will have a stab at describing what GM crops could
mean for our health and the environment, and also how best the technology
should be controlled. The report will carry a lot of weight, heavily
influencing the government's decision on what has become one of the most
contentious of modern issues: should Britain become a GM nation? These
are some of the key questions and the scientific studies carried out to
address them.

Is GM food safe to eat?

Genetically modified crops invariably have genes added to them, making
them churn out proteins they wouldn't normally produce. Can these genes,
proteins or any other changes caused by the GM process make food
dangerous to eat?

Evidence

The most famous paper on the safety of eating GM foods was published amid
huge controversy in the Lancet in 1999. The report, by Arpad Pusztai of
the Rowett Research Institute in Aberdeen (before the furore cost him his
job) and Stanley Ewen at Aberdeen University, claimed that feeding rats
GM potatoes damaged their stomach linings. But the report was largely
rubbished by scientists. The Royal Society, and even the Lancet's own
advisers, dismissed it. Since then, studies by bodies such as the UN's
Food and Agricultural Organisation, the International Union of
Nutritional Sciences and the Royal Society have all concluded that the GM
foods currently on the shelves in other countries are safe to eat.

A huge unofficial experiment is going on, thanks largely to the
population of the US. Between them, they have eaten millions of meals
containing GM food since 1995 with no apparent problems. The only hint of
danger came in 2001 when a type of GM maize, approved only for animal
feed because it contained a potentially allergy-inducing protein, got
mixed up with normal maize and turned up in tacos in the US. Some of the
people who ate the tacos complained of a range of ailments, but the US
Food and Drug Administration was unable to confirm or rule out whether
the GM maize was to blame.

Verdict

There is no evidence that today's GM food is unsafe to eat, but according
to Janet Bainbridge, who chairs the government's advisory committee on GM
foods, it is impossible to be certain that any food is 100% safe. "You
can never guarantee absolute safety, but the GM foods that have been
through the process are as safe, if not safer, than conventional
alternatives," she says.

Each new GM crop will have to be tested to ensure it doesn't produce
allergenic proteins or has changed in any other way that could make it
dangerous to eat. Bainbridge says this will quickly become the biggest
issue for GM food safety - as GM foods become more complex, far more
sophisticated equipment will be needed to ensure they are safe.

Will GM crops feed the world?

Some groups claim that GM crops will bring higher yields and so help
provide food for the world's hungry.

Evidence

Several studies have shown GM crops can increase yields, especially if
they are resistant to pests. A review of research by Janet Carpenter at
the National Centre for Food and Agricultural Policy in Washington DC
found that pest-resistant GM corn upped yields in America by the
equivalent of 500,000 acres a year. Higher gains have been reported in
developing countries.

Verdict

GM crops can boost yields, but according to Clive James, chairman of the
International Service for Acquisition of Agri-Biotech Applications, a
charity concerned with alleviating poverty in developing countries, it
will take more than GM technology to solve the problem of world hunger.
"It's always going to take more than just GM technology, but it can and
is making a real contribution to these countries that need it most," he says.

Will GM crops put organic farmers out of a job?

Organic produce must be free of GM products, but because GM crops are
capable of crossing with non-GM varieties, some worry they could threaten
the purity of organic produce.

Evidence

Studies show separating fields of GM crops from organic crops can reduce
the amount of contamination, but achieving zero contamination is next to
impossible. Given the go-ahead by the government, the first GM crops to
be planted in the UK would be oilseed rape, sugarbeet and maize. Pollen
from oilseed rape travels the furthest - up to three kilometres on the
wind - and so is most likely to contaminate non-GM varieties. Maize and
sugarbeet pollen travels less far and sugarbeet poses much less of a
threat as it doesn't usually flower before being harvested.

Verdict

Unless GM and organic crops can be kept far enough apart, cross
pollination is almost a certainty. Introducing mandatory separation
distances could work for sugarbeet and maize, but it may prove impossible
to grow oilseed rape organically if GM rape is introduced. Farmers
reliant on a limited range of organic crops are likely to suffer
significantly.

Will GM crops harm farmland wildlife?

GM crops are often used with so-called broad-spectrum herbicides that
wipe out everything with leaves except the crop. Some groups, including
English Nature, the government's advisory body on wildlife, are concerned
that the broad-spectrum herbicides will destroy so many weeds, there
won't be enough for insects and other creatures to feed on. If the
numbers of beetles, bugs, butterflies and other creatures wane on GM
farms, the knock-on effect on other animals, such as skylarks, could be huge.

Evidence

The only major investigation into how growing herbicide-resistant GM
crops affects farmland creatures in Britain is the government's so-called
field scale evaluations. Though the studies were completed some time ago,
the results will not be published until late autumn. Another study,
however - a computer simulation developed by Andrew Watkinson's team at
the University of East Anglia - found that by wiping out weeds and their
seeds, broad spectrum herbicides could slash the amount of food available
for farmland birds. One positive study, by John Pidgeon's group at
Broom's Barn in Suffolk, found that if farmers used herbicides
judiciously, weeds and bugs could flourish without denting yields.

Verdict

Watkinson's work suggests that, if used carelessly, broad-spectrum
herbicides could turn farmlands into almost lifeless wastelands. While
Pidgeon's study is positive, it relies on farmers wanting more weeds and
bugs on their land, something Pidgeon admits they are only like to want
if paid for it. Most scientists admit there will be an impact, but how
bad it is will depend on farming style and the local environment.

Will GM crops lead to superweeds?

The vast majority of GM crops available now are either resistant to
certain herbicides or produce toxins that kill pests. Some worry that
these traits could turn GM crops into rampant superweeds if they manage
to escape the confines of farmers' fields. Another concern is that GM
crops might turn other plants into superweeds by crossing with them.

Evidence

There's no evidence that herbicide-resistant GM crops will become
superweeds. In one of the largest studies carried out, Mike Crawley at
Imperial College, London, planted GM crops next to natural varieties in
fields from Cornwall to Scotland. When he checked them 10 years later in
2001 he found all of the GM crops had died out. This is not surprising:
being resistant to herbicides in the wild, where no herbicides are used,
is more of a burden than a benefit.

Some GM crops certainly have the potential to give rise to superweeds if
they can cross with other plants. A major study carried out by Allison
Snow at Ohio State University showed that when normal sunflowers were
crossed with GM varieties that had built-in pest resistance, they not
only inherited the insect-repelling genes, they produced more seeds than
normal sunflowers, probably because insects on them died before causing
too much damage. Weeds can also turn into superweeds simply by years of
exposure to herbicides.

Verdict

Herbicide-tolerant GM crops won't produce superweeds, but GM crops with
built-in pest repellents could, if they cross with wild relatives. In the
UK, the only GM crop that is likely to cross with wild relatives is
oilseed rape.

Are herbicides used with GM crops better than traditional herbicides?

Giving GM crops the green light means a shift in the type of herbicides
farmers will use, from older herbicides that target specific weeds to
modern herbicides that kill all weeds on contact. Some groups fear the
newer herbicides could cause more harm to the environment than those
commonly in use already.

Evidence

Several studies have shown that modern broad-spectrum herbicides are less
toxic to soil organisms and break down more quickly than older
herbicides. Whether farmers use more or less herbicide growing GM crops
is contentious though. In 2000, the US Department of Agriculture found
that the amount of herbicide used since the introduction of GM crops
hadn't changed. Other researchers have found marginal increases and decreases.

Less contentious is that GM crops could allow farmers to cultivate crops
with little or no tilling. Tilling is great for killing weeds, but the
benefits of not tilling are huge: it saves huge amounts of energy and
estimates suggest up to 45 billion tonnes of soil a year are lost
globally to tilling by being blown away or lost to rainwater. The
herbicides used with GM crops could allow farmers to destroy weeds
without tilling.

Verdict

While the herbicides used with GM crops do appear to be more
environmentally friendly, the environmental impact of switching to them
depends largely on how responsible farmers are in their usage. Some GM
crops could be farmed with less tilling, saving energy and soil.

Will pest-resistant GM crops kill other creatures by accident?

Plants are already good at using chemicals to kill: caster beans, for
example, produce ricin which can kill a human in 36 hours. To make GM
crops resistant to pests, they are most commonly modified with a gene
taken from a common soil bacteria called Bacillus thuringiensis (Bt).
This bacterium produces a chemical that kills certain insects, by
punching holes in the lining of their stomachs. Some worry so-called Bt
crops may kill far more than just pests that threaten the crop.

Evidence

The most famous investigation into whether Bt crops could harm insects
other than crop pests was carried out by John Losey at Cornell University
in New York. He found that when the larvae of monarch butterflies ate
pollen from Bt maize in the lab, it either killed them or stunted their
growth. But he later showed that under real life conditions, larvae would
be unlikely to eat enough of the toxic pollen to be a problem. Other
studies have found knock-on effects of Bt crops: insects have been found
to pop their clogs after feeding on crop pests that themselves keeled
over after eating Bt crops. In many of these studies though, the pests
had unrealistically large helpings of the crops.

Verdict

Toxin-producing GM crops will probably poison insects and other creatures
they are not designed to, but too little work has been done to assess how
big a problem this could be.

Will GM crops lead to pesticide-resistant insects?

Just as infection-causing bacteria can become resistant to antibiotics,
some fear the widespread planting of pest-resistant GM crops will give
rise to a new breed of "superpests".

Evidence

Some pests have already developed resistance to chemical sprays and in
the US and southern Europe, diamondback moths have become resistant to Bt
sprays used by organic farmers. In the lab, tests have shown pests can
become resistant to GM crops but superpests have yet to be found in the wild.

Verdict

Pests will very likely become resistant to the toxins produced by certain
GM crops, but it won't happen overnight or even in a few years. The
threat of superpests in Britain is minimal since most pest-resistant GM
crops don't target pests found here, so there's little reason to farm
them. "It's places where there are lots of crops and lots of pests that
you have to worry about," says Neil Crickmore, an expert on Bt toxin at
the University of Sussex. Eventually, new technologies that make crops
produce more than one pesticide will be needed to slow down the
development of resistance."

How can GM food be identified?

Many feel GM foods need to be strictly regulated and monitored so they
can be taken off the market if problems arise.

Evidence

Last summer, the biotech company Aventis Cropscience admitted that GM
seeds it supplied for government trials had accidentally been
contaminated with other GM seeds. It was just one incident where a mix up
meant GM produce got where it wasn't wanted. One method scientists have
developed to ensure segregation of GM from non-GM food is a genetic
identification code that can be built into crops.

Verdict

The main tool for monitoring GM food will be simple labelling. Although
it has raised tensions with the US, where labelling is not compulsory,
European ministers voted this month for the mandatory labelling of any
food containing more than 0.9% GM ingredients. If any problems occur,
labelling should go some way to allowing the source to be quickly identified.

There's no doubt the introduction of GM crops into Britain will have an
impact - on everything from the plants and creatures of the countryside
to farmers and the general public. The issue the government will have to
face is how much risk GM is worth. Ultimately it will have to assess each
GM crop on a case-by-case basis, working out what threats it poses and
what benefits, if any, it affords. As Pidgeon says: "People on the far
left or the far right of this debate are just barking [sic]. You can't
generalise." The government is set to begin ruling on GM crops for
Britain before the end of the year.




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