Times : GM crops leak powerful toxins
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- From: Herve LE MEUR <Herve.LEMEUR@math.u-psud.fr>
- Date: Fri, 3 Dec 1999 11:02:30 +0100 (MET)
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THE TIMES THURSDAY DECEMBER 2 1999
GM crop toxin is leaking into the soil
BV NICK NUTTALL ENVIRONMENT CORRESPONDENT
SOME genetically modified crops are leaking powerful toxins from
their roots into the soil, scientists have found.
Researchers described the findings as "surprising and unexpected",
raising fresh fears about the environmental impact of such crops.
Companies have modified plants to produce poisons or toxins to combat
the pests that eat their stems and leaves. But the discovery that the
same plants are also leaking toxins into the soil has not, until now,
been considered an issue.
It will raise fears among some scientists, regulators and
environmental groups that beneficial soil organisms might be killed
and that in- sects living in the soil might become resistant to the
The findings, published to- day in Nature, have been re- leased by a
team at the Univer- sity of New York that has been studying the roots
of GM maize.
Several crops, from maize, to corn and potatoes, have been genetically
modified to kill insect pests using a gene derived from a bacterium
called Bacillus thuringiensis (BT). In the United States 15 million
acres of corn modified with the BT gene were planted in 1998 or just
under 20 per
cent of the total crop. GM maize has also been planted in Europe
although the acreage is far smaller.
Concerns about the impact of such crops on the environ- ment were
triggered earlier in the year when it was found that monarch
butterflies had died after feeding on milk- weed dusted with pollen
from GM corn.
Other research found that lacewings that had fed on corn borers reared
on BT corn had also died, raising concerns that such crops are harming
more than just pests.
Professor Guenther Stozky, of New York University's labo- ratory of
microbial ecology, who has led the research, said yesterday that the
monarch re- search showed that the toxin was released from the pollen.
"Now we have found it is also continuously released from the roots
into the soil. The fact that the toxin is re- leased from the roots
was unex- pected," he said.
Professor Stozky said that the BT toxin was a large pro- tein molecule
which they had considered too large to cross the root membrane.
During the research, the team grew GM seedlings in the laboratory for
25 days. Each plant produced on average 105 microgrammes of pro- tein
and this was tested against larvae of the tobacco hornworm. Up to 95
per cent of the larvae died after five days with 50 per cent killed at
a dose of just 5.2 micro- grammes of protein.
Because the roots are constantly leaking the toxin, there is also the
risk that pests in the soil might rapidly become immune to the poison
triggering new, resistant, strains.
Biotechnology companies are likely to claim that, because the
bacterium from which the BT gene is taken, is found in the soil the
toxin is naturally part of the environment underground. But Professor
Stozky challenged such assertions, claiming that the bacterium was not
prevalent in the soil.
Dr Doug Parr, of Greenpeace said that the findings underscored the
"ability of GM crops to wrong-foot their creators and produce
unexpected and unwanted effects".
Dr Penny Hirsch, a soil expert at lACR-Rothamsted in Harpenden,
Hertfordshire, said yesterday that the findings were "interesting" but
added that field tests were needed to see whether the effects in the
laboratory were happening in the real world.