One of the corn varieties was designed to tolerate broad-spectrum herbicides, (so-called "Roundup-ready" corn), while the other two contain bacteria-derived proteins that have insecticide properties. The study made use of Monsanto's own raw data.
Quoting from the study's 'Conclusions' section:
"Our analysis highlights that the kidneys and liver as particularly important on which to focus such research as there was a clear negative impact on the function of these organs in rats consuming GM maize varieties for just 90 days."
Given the very high prevalence of corn in processed foods, this could be a real ticking time-bomb. And with food manufacturers not being required by law to declare GMO content, I think I'll do my best to avoid corn altogether. Pass the puffed rice and pour me a glass of fizzy water!"