GMOs are not bad for health but they are quite bad for overall biodiversity and genetic variability of crops. Old crop varieties are being decimated (not just by GMOs but also other commercial strains) and with them comes a real threat to food security because the ability of crop to resist some disease is in direct correlation with it's genetic diversity. Take bananas - almost all commercial bananas are the same, they are considered very much threatened because of that. Some say they are already extinct but they don't know it yet :) GMs are making this problem much worse and science is doing nothing to solve this problem... its actually causing it.