Hello Mike. Bt corn expresses NOT the inactive crystalline poison
which the Bt bacterium makes, but the semi-activated delta-endotoxin.
The Bt gene in corn has also been modified to be 40 times or more
stronger than the natural toxin. Because of these, your concerns are
valid that the Bt corn toxin may cause unintended problems with other
organisms.
>Has anybody done real tests on this and not just assumed the problem
>away because they already "know" Bt only affects lepidoptera?
Monsanto, creater of Bt corn MON810, itself admits that its Bt corn
produces the delta-endotoxin in semi-activated form. But the argument
they use to support claims of safety are:
1. the toxin will only bind to a specific receptor present in the guts
of some insects; the mammalian gut does not have such a receptor
2. they have tested the delta-endotoxin (but made with E.coli, not
from Bt corn) with rats, and no harmful effects were observed;
therefore, "the toxin is safe to mammals, as expected"
3. there is no similarity ("homology") between the Bt toxin and other
known toxins or allergens
A Novartis researcher fed broiler chicken with Bt corn (published
1998), and also found "no harmful effects".
These are all the feeding studies so far with respect to Bt corn.
None have been done on primates or human volunteers.
The US FDA and EPA exempted Bt corn from thorough testing (that
pesticides and drugs go through) because they considered Bt corn
"substantially equivalent" to conventional corn; so if conventional
corn need not go through such tests, neither should Bt corn, so goes
their argument.
Roberto
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