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ISIS Report 01/12/03
Regulatory Sham on Bt-Crops
Prof. Joe Cummins exposes the
regulatory sham involved in GM crops containing a range of biopesticides
Sources
for this report are available in the ISIS members site.
Full details here
At 80 million planted acres, corn is the largest crop grown in the US
and accounts for one fifth of total agricultural cropland. Over the past years,
conventional insecticides have been applied to between 14 to18 million acres of
corn to control corn root worm (CRW). This single corn pest accounts for over
14% of insecticide applications to agricultural crops. Infested acreage is
increasing due to extended diapause and change in the insect’s behaviour
as the CRW lays its eggs in soybean fields, which are planted in rotation with
corn.
Currently, the main genetically modified (GM) corn contains the
Bacillus thuringiensis (Bt) toxin gene Cry1Ab to control corn borer, but
does not control CRW. CRW control has been the recent focus among the
corporations developing GM crops. All candidate crops are being raced to market
with the cooperation of regulatory authoritatives in the US and Canada. The
emphasis is on speedy evaluation and keeping down costs rather than to ensure
safety to consumers and to the environment. Safety testing is done using toxins
produced in bacteria acknowledged to be somewhat different from those produced
in the corn plants. This is deemed to be "sound science" by the regulators.
GM corn with genes providing protection against CRW will soon reach the
market. Monsanto corporation has focused on the Bt toxin Cry3Bb and has
recently developed synthetic Bt toxins that combine amino acid sequences from
native Cry1Ac and Cry1F crystal protein, which have enhanced broad range
specificity lacking in either toxin individually. Dow corporation has been
developing corn with Cry34Ab/Cry 35Ab combined toxin. Monsanto’s
Cry3Bb-corn is ready for commercial release and the others will soon
follow.
Patents describing the production of Bt-Cry3Bb describe the production
of the synthetic Bt genes both used to produce the toxin produced in bacteria
and the toxin produced in corn plants. The synthetic Bt-cry3Bb is altered from
the bacterial gene by insertion of the cauliflower mosaic virus (CaMV) promoter
and enhancers, the leader sequence of wheat chlorophyll a/b binding protein,
the rice actin intron, and the 3’ transcription terminator sequence of
wheat heat shock protein 17.3. Along with the sequences above, many code words
for amino acids were altered to enhance translation in the plant cell, and some
amino acids were changed to enhance performance in the plant cell. An
antibiotic resistance marker nptII, also with the CaMV promoter and the NOS
transcription terminator from Agrobacterium tumefacians nopaline
synthetase gene was inserted into the corn chromosome along with the Bt-cry3Bb
construct The genetic insert in corn was called MON 863. The US Food and Drug
Administration (FDA) noted that the Bt toxin in Mon 863 differed from the
bacterial toxin by seven amino acids and by an additional amino acid, alanine
in the second position from the start of the protein.
US Environment Protection Agency has considered a large number of
documents on human health and environmental impacts of Mon 863 corn. The
petition to establish a tolerance exemption for Bt-Cry3Bb argued that it was
not necessary to set a tolerance level because the toxin was not toxic to
mammals. But the studies supporting the exemption were done with toxin produced
in bacteria that are not identical to the product in Mon 863 corn. The
biopesticides registration action document for event MON863 Bt-Cry3Bb1 corn
provided information on product characterization. The action document on
environmental assessment included evidence on non-target wildlife, but reviewed
data from the bacterial Bt- Cry3Bb1 toxin, and not the toxin produced in MON863
corn. EPA has also provided a fact sheet on Bt-Cry3Bb1 protein and the genetic
material necessary for its production.
Canada approved MON863 corn for livestock feed on March 5, 2003. Limited
information was provided in the Canadian decision document, and the fact that
the safety investigations had been based on a product significantly different
from the toxin in MON863 corn was not mentioned. The approval of GM crops
bearing toxins whose safety tests have been based on tests of surrogate
products appears to have grown so commonplace among regulators that it is not
worthy of mention.
Dow Agroscience Corporation has been developing a binary toxin mixture
containing Bt- Cry34Ab1 and Bt-cry35Ab1 effective against CRW. Initial safety
tests using toxins produced in bacteria showed that the mixture was digestible
by mammals and for that reason unlikely to be allergenic. The petition to EPA
for tolerance exemption, and the granted temporary exemption noted that the
proteins were obtained from bacteria but believed to be similar to the proteins
produced in corn (the product being regulated) because the products had similar
gel electrophoresis mobility. The actual differences between the synthetic
genes in corn and the protein they produce and the protein toxins produced in
bacteria from the native gene have not yet been disclosed.
Monsanto recently (Nov. 11,2003) disclosed methods for the construction
of B. thuringiensis hybrid delta-endotoxins comprising amino acid
sequences from native Cry1Ac and Cry1F crystal proteins. These hybrid proteins,
in which all or a portion of Cry1Ac domain 2, all or a portion of Cry1Ac domain
3, and all or a portion of the Cry1Ac protoxin segment is replaced by the
corresponding portions of Cry1F, possess not only the insecticidal
characteristics of the parent delta-endotoxins, but also have the unexpected
and remarkable properties of enhanced broad-range specificity not displayed by
either of the native delta-endotoxins. The hybrid toxins incorporated into
transgenic plants express broad-spectrum insecticidal activity against a
variety of coleopteran, dipteran, and lepidopteran insects. Presumably, the
deployment of the synthetic genes, described above, is meant to provide
protection against all of the major insect pests of corn. It seems likely that
the mammalian toxicity tests and the test of impact on non-target animals will
be done with the protein produced in bacteria not the one produced in corn
plants.
In spite of the clear differences between the genes and the insecticide
toxin proteins produced in bacteria and those produced in transgenic plants the
US and Canadian regulators have agreed with the corporations manufacturing the
GM crops that the products are substantially equivalent. So long as the final
toxins are similar the bacterial toxins can be used as surrogates for the crop
toxin in safety testing. The regulators made little or no effort to directly
test the validity of their presumptions. They are placing the burden of proof
that the toxins in the GM crops are unsafe for mammals and the environment on
the shoulders of the public, not the corporations who profit from the GM crops.
In the final analysis, the regulators are providing essential public relations
benefits for the corporations but not adequately protecting the public. And so
long as GM crops are not labeled in the market, the errors of the regulators
will go undetected.
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