We Say... Although natural Bt toxin, which is derived from a common soil bacterium, has a history of safe use when used as an insecticidal spray in traditional and organic farming, it is applied to the outside of the plant and eventually degrade when exposed to the elements.
In contrast, the Bt toxin engineered into the Bt crops are switched on all the time and act differently than the natural. GM Bt crops have been shown to harm monarch butterflies as well as beneficial pest predator insects helpful to the farmers (ladybugs, and lacewings for example). In animal testing, GM Bt corn has been found to be toxic in laboratory and farm mammals.
It appears that Bt toxins are not destroyed by cooking nor by the digestive process. So, since these toxins end up in our small and large intestines, they can kill the friendly bacteria living there that helps us to stay healthy. So you know, since testing Bt corn on humans is illegal, it is hard to prove. But if we look at the results shown on mice and farm animals, it would not take a big jump of faith to extrapolate that it could be harmful to humans as well. Meanwhile, since we are eating these Bt toxin-laced foods daily, I am concerned that we may be the lab rats in this vast scale experiment.