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Why Bt Cotton Should Be Banned

Why Bt Cotton Should Be Banned

THE HINDU (India)
September 6, 2001

The Hindu-Editorial: Should India say yes to Bt crops?

IN JUNE this year, the Genetic Engineering Approval Committee (GEAC),
set up by the Government of India for licensing genetically-modified (GM)
crops, deferred the commercialisation of Bt cotton. The GEAC decided on
large-scale trials to be conducted in different agro-climatic conditions, henceforth
under the direct supervision of the ICAR. The spokesperson for the
Confederation of Indian Industry termed it an "unfortunate decision... a
classic example of bureaucratic delay". The Chairperson of the GEAC, Mr. A.
M. Gokhle, defended it saying, "as the technology is new to us, we did not
want to take any chance". Is the GEAC right in adopting a cautious approach?
Why do we not try to learn from the experience of this technology,
especially in the U.S. where it is not so new?

We must begin by mentioning that the spray of Bt or Bacillus thuringiensis,
a common soil bacterium, is probably the single most important biological
pest control technique in use worldwide. What the genetic engineers have
done is to develop transgenic crops containing the insecticidal gene of Bt,
so that the plant itself makes the protein necessary for protection against
pests. This has been perhaps the single biggest commercial application of
r-DNA technology in the world so far. Cotton, corn and potato engineered
with this gene were grown commercially in the U.S. for the first time in
1996. Companies producing these transgenic crops promote them as a way of
reducing farmers' dependence on harmful pesticides. However, experience over
the last five years reveals problems that place a question mark on this
entire approach to pest control. In fact, there is growing concern that the
very effectiveness of Bt as a bio-pesticide could be irrevocably endangered
if use of Bt-transgenic plant varieties is not stopped immediately. Rigorous
field studies of teams led by Bruce Tabashnik (University of Arizona) and
Fred Gould (North Carolina State University), both reported in recent years
in the Proceedings of the National Academy of Sciences, U.S., provide solid
evidence of insect resistance to Bt cotton.

Since resistance has become a major worry, companies now insist that farmers
follow resistance management plans (RMPs), which include "refugia" (keeping
a certain proportion of fields free of Bt seeds and insecticides). These
fields are to be the refuge of susceptible insects, thus slowing down
evolution of resistance against the Bt gene. However, Tabashnik's team has
questioned two fundamental assumptions behind all Bt RMPs - that resistance
to Bt is a rare recessive trait and that cross-resistance to Bt endo-toxins
is uncommon. The idea that resistance could be delayed through the use of
two or more endo-toxins has, thus, been seriously undermined.

Further, field data show that expression of toxins in Bt- transgenic crops
can develop unevenly in different parts of the plant. In one report, Bt
toxin expression was found to be 90-95 per cent in the top part of the plant
but only 20-25 per cent in the lower nodes, making them more susceptible.
Since the lower nodes often produce the highest quality cotton, their loss
is even more significant. Bt toxin expression also typically starts out high
in the early part of the season but tapers off over time.

It is also inadequate in harsh environmental conditions such as drought.
This "sub-lethal dose" of the toxin can facilitate the development of
resistance over time, just as it happens with pathogenic bacteria when we
fail to complete the necessary course of antibiotics. Uneven expression of
Bt in the crop could also accelerate emergence of "behavioural resistance"
(M. Harris, Science, 1996), because insects may sense which parts of the
plant to avoid. In India, with so many difficult agro-ecological conditions
and millions of poor farmers, Bt-transgenic crops are likely to grow
unevenly across farms leading to many cases of sub-lethal doses of the Bt
toxin and, therefore, resistance might be engendered at an even faster rate.
Estimates of how long resistance can be delayed vary, but the average figure
in most research, even in the relatively favourable circumstances of the
U.S., is not more than five years. So powerful demands are being made that
the Environment Protection Agency (EPA) should delay any further approval of
Bt- transgenic plant varieties, and that previous approvals should be
reversed when evidence points to imminent failure of an RMP. In any case,
the EPA had granted only conditional registration to Bt crops in 1995,
mainly due to fears that pest resistance could develop. Unlike risks of
conventional pesticides that are typically limited to specific circumstances
of use and location, and can be conceivably tackled, risks following
Bt-transgenic resistance are essentially irrevocable. Once resistance genes
emerge and gain a foothold in populations, they cannot be recalled. And the
worst part is that they would also foster resistance against the Bt spray,
ultimately destroying the effectiveness of this safer bio-pesticide.
Even more worrisome than Bt cotton has been the history of StarLink, a
transgenic Bt corn containing one of the family of Bt proteins (Cry9C),
developed for control of European corn borer and Southwestern corn borer,
and for suppression of black cut worm and corn stalk borer. Cry9C is a
protein for which there is no history of human dietary exposure. It has
several properties characteristic of food allergens. In August 1997, Plant
Genetic Systems (later acquired by AgrEvo, subsequently taken over by
Aventis) applied for registration of StarLink corn.

The EPA approved its use in May 1998 only as animal feed and for industrial
purposes. In April 1999, AgrEvo again petitioned the EPA to permit use of
StarLink for human consumption. The EPA set up a Scientific Advisory Panel
(SAP) comprising 16 physicians and independent scientists to advise it on
the matter. In its report to the EPA in December 2000, the SAP concluded,
"there is a medium likelihood that Cry9C protein is a potential allergen",
thus rejecting the use of StarLink corn in human food. The SAP met once
again in July 2001 to consider fresh studies by Aventis and others but found
no reason to alter its recommendation of banning StarLink from human food.
The panel found that Cry9C shows both heat stability and resistance to
digestion, the two best available criteria presently known for ascertaining
food allergy proteins. Too many questions remained about StarLink causing
allergic reactions such as rashes, breathing problems, gastrointestinal
upset or even anaphylactic shock.

Indeed, already in September 2000, some of America's favourite taco shells
(Taco Bell), sold in grocery stores nationwide, were found to be illegally
contaminated with StarLink. Kraft immediately recalled them from the market.
Subsequently, nearly 300 other processed foods were also recalled following
StarLink contamination. The registration of StarLink was cancelled and
future planting of stocks of StarLink was prohibited. The U.S. Department of
Agriculture and Aventis made aggressive efforts to remove StarLink from the
market, all of which is expected to disappear by 2002.

The most extraordinary twist to this story is that even as the Americans
were busy trying to get StarLink out of their system, the Clinton
administration decided in October 2000, to lift export restrictions,
allowing shipments of previously banned StarLink corn to Latin America, Asia
and Europe. Of course, the vigilant Japanese Ministry of Agriculture
immediately responded saying they would not allow StarLink corn to find its
way into their food supply. It is to be hoped that the Indian Government
will show the same sagacity and alertness to foil attempts to dump
discredited and discarded products into our markets and prevent "splicing"
of a doubtful technology into our thrust areas of research.
(The writers are, respectively, Director, Baba Amte Centre for People's
Empowerment, and Secretary, Samaj Pragati Sahayog, both based in Madhya
Pradesh.)


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