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New Scientist (UK) July
6, 2002
Drug genes could enter food chain
BY Philip Cohen; San Francisco
Loopholes in US regulations raise fears that
food crops will be contaminated with pharmaceuticals
THE rules the US government is proposing for
field tests of crops that have been genetically modified to produce
pharmaceutical products are not strict enough to prevent the contamination
of food crops, experts have told New Scientist.
They say the proposed rules are based on flawed
science, that there are loopholes allowing them to be bypassed,
and that companies do not even have to disclose what genes have
been added. And they warn of severe environmental consequences if
a drug-laced plant were to breed with other crops or wild relatives.
Biotech companies plan to produce a vast range
of products, from drugs to vaccines, in plants. "These plants have
the potential for more benefit than any other agribiotech product,"
says Jane Rissler of the Union of Concerned Scientists in Washington
DC. "But to realise those benefits we have to be very careful about
the risks." The US Department of Agriculture's (USDA) plans don't
come close, she says. What scares Rissler and others is that there
could be a rerun of the Starlink debacle, in which GM corn strictly
not intended for human consumption ended up on grocery shelves.
If any contamination involved a crop producing a potent drug, the
consequences could be far more serious, she says.
The proposed rules require the "pharmed" plants
to be separated from other crops in time as well as space. For example,
pharmed maize must be grown at least 400 metres away from other
maize. It must also be planted two weeks before or after nearby
crops, so that it isn't fertile at the same time. Similar regulations
have been outlined for other plants that have been engineered to
make drugs, including barley, corn, rice and sugar cane. But when
it comes to keeping harvested products separate, the rules are vague,
talking only of "adequate identification, packaging and segregation".
Companies that violate these procedures can be
fined $250,000, and individuals could face jail sentences of up
to five years. James White, the USDA's branch chief for biotech
evaluations, is confident the rules will do their job: "The chance
of gene flow is essentially zero."
"These rules are more stringent than prior recommendations,
and I applaud that," says Norman Ellstrand of the University of
California, Riverside, who sat on a National Academy of Sciences
committee that reviewed the regulations for GM crops. "But there
are big holes in the system."
The NAS report points out that some of the USDA's
rules have no clear scientific rationale. For instance, the isolation
distance for corn is simply double the 200 metres it recommends
for the production of GM seeds. The assumption is that this spacing
will reduce contamination to 0.1 per cent, but there is no evidence
that the contamination risk drops off with this increase in distance.
Only last week, Australian researchers reported that pollen from
oilseed rape had contaminated fields up to 3 kilometres away, and
that there was no obvious drop-off with distance (Science, vol 296,
p 2386).
Another serious concern is that the USDA focuses
on the intended use of a crop product and ignores its other possible
impacts. For instance, the Texas-based company Prodigene applied
to grow maize that produces a chicken-egg protein called avidin,
which is known to kill or harm 26 species of insects. But because
avidin is not classed as a drug, the crop doesn't come under the
pharming regulations. Nor did the USDA look at the maize's environmental
impact because the crop wasn't being grown in order to kill insects.
"If they had used the same protein as an insecticide, they would
have called in the Environmental Protection Agency to regulate it,"
says Ellstrand.
While avidin's properties are well known, that
is not the case with every drug that might end up being grown in
crops. Ellstrand and his colleagues were disturbed to discover that
the publicly available descriptions of genes spliced into some plants
are incredibly vague.
White says the USDA will start posting fact sheets
on genes in transgenic plants later this month. When a company wants
to keep the identity of a gene secret, it will give it a code name
and a general description, such as "Gene S is a hormone in humans.
It is harmless to invertebrates," and so on.
He also says the only drugs so far being grown
in crops are proteins that would simply be digested if accidentally
eaten by humans or animals. "The risks are minimal," White says.
"No one is making Viagra in a field." But there's nothing to stop
companies producing a Viagra crop if they want to. "It's a disaster
waiting to happen," says Doreen Stabinsky, a science adviser for
Greenpeace. "Grow this stuff in a greenhouse or a cave, not in an
open field where animals can grab the seeds."
Ellstrand agrees that stricter containment is
needed. Pharmed plants could be genetically engineered to prevent
gene flow using methods such as the infamous Terminator technique,
which makes seeds sterile, or a newly proposed one dubbed the Exorcist
(see "Begone! evil genes"). And to be absolutely certain the food
supply is safe, he argues that only plants that aren't grown for
food should be used to make drugs.
White points out that when the long-awaited regulations
are finally published, the public will have 120 days to respond.
"I wouldn't be surprised if we got thousands of letters telling
us: not in food."
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