There are many, many reasons to oppose GMOs: 1) The IP system and the companies who exploit it to essentially disrupt agriculture (licences to grow seeds, cann

There are many, many reasons to oppose GMOs: 1) The IP system and the companies who exploit it to essentially disrupt agriculture (licences to grow seeds, cannot replant, must buy seeds annually, aggressive lobbying, regulatory capture). This is upsetting to the agricultural status quo (political and economical) in Europe (their farm subsidies would essentially be funnelled to foreign corporations). There is also the use of courts to abuse the IP system, where farmers who unknowingly grow patented seeds (pollen drift or seed stock contamination) get sued, instead of the other way around (farmers should be able to sue--and win against--GMO companies for contaminating their farm with unwanted plants). 2) The issue of eating the produce of GMO plants. On the health side, many (industry-funded) studies show no effect (surprise, surprise), watchdog groups say the industry covers up any bad results, while some independent long-term studies are starting to uncover problems (though results and methods are controversial). Then there is labeling and the fundamental right of people to know what they buy and ingest. 3) Huge but not mentioned yet: the environmental impact of the large (and growing) herbicide applications required by GMO crops (the glycophosphate-resistant varieties, but ther are other herbicides and pesticides involved). Again, this is a multifaceted impact: water runoff and groundwater contamination, impact on the polinators and other sub-ecosystems, evolution of resistent "super-weeds," escalation to other herbicides such as derivatives of Agent Orange. The fact that Monsanto sells the herbicides as well further muddies the problem (it is biased towards not seeing any environmental impacts). The problem is that environmental impacts take years to build up, become significant, and be pinpointed through studies--and by then it's too late.