Rats fed with Monsanto's (MON +1.7%) GM corn in a French study, or exposed to its Roundup weedkiller, suffered mammary tumors, and severe liver and kidney damage. Around 50% of males and 70% of females died prematurely vs. 30% and 20% in the control group. However, the lead researcher has a record as a critic of the GM industry, so other experts may be wary of drawing quick conclusions.