The amount of toxins left in the corn is insane compared to early data from the 90s:

“The first GM corn varieties in the late 1990s expressed 2 ppm to 6 ppm (parts per million) of one or two Bt toxins in corn kernels, the part of the plant people eat,” explained Charles Benbrook, one of the authors of the submission. “Today’s leading GM corn varieties express four to seven toxins in corn kernels and at much higher levels, 50 ppm to 100 ppm. Why the big increase? Because target insects become more tolerant to Bt toxins over time, and eventually fully resistant. This forces the seed-biotech industry to add in new GM toxins and engineer the plants to express them at much higher levels. That might help kill more insects for a short time, but it also steadily increases human food safety risks.”

That level of difference is insane. The article also links to detailed article on the more recent studies the Mexican Government pulls from

Recent studies have shown negative health impacts to the gastrointestinal tract and potential damage to the liver, kidneys, and other organs.

link to the study from Mexico directly