GMO Not Safe: Scientific Report from Europe and Studies on Health Dangers of Round-Up (glyphosate)
A scientific report from Europe documents, with references, that there is no scientific consensus on GMO safety. They point out that there are no epidemiological studies investigating potential effects of GM food consumption on human health. 
Claims that scientific and governmental bodies endorse GMO safety are exaggerated or false. The Royal Society of Canada issued a report critical of regulatory systems for GMO in Canada and declared that it is “scientifically unjustifiable” to presume that GM foods are safe. 
A report by the British Medical Association concluded that “many unanswered questions remain” and that “safety concerns cannot, as yet, be dismissed completely on the basis of information currently available”. 
A big reason GMO foods are so dangerous is the vast majority (in terms of amounts in the food chain) are Monsanto Round-Up-Ready seeds (corn and soy especially), that then result in enourmous amounts of Round-Up (glyphosate) being sprayed on the fields and getting into the food chain. Numerous studies have been published showing the health dangers of glyphosate.
Jan 15, 2014 ,”Glyphosate Commercial Formulation Causes Cytotoxicity, Oxidative Effects and Apoptosis on Human Cells: Differences With its Active Ingredient”. This study showed severe health risks of increased reactive oxygen species, nitrotyrosine formation, superoxide dismutase activity, and glutathione induction, along with caspase 3/7 activation inducing apoptosis from the commercial preparation of glyphosate (Round-Up), while the isolated glyphosate molecule and aminomethylphosphonic acid (AMPA) showed no such toxic effects. Clearly, the commercial product has added toxicity (added adjuvants) with grave health consequences. 
November 2013 the journal Toxicology published the article “Ethoxylated adjuvants of glyphosate-based herbicides are active principles of human cell toxicity. This article points out that glyphosate (Round-up), the major pesticide used in the world, while alone is often found to be safe, but when combined with adjuvants (generally thought to be inert and harmless) is extremely toxic to human cells down to 1 ppm (part per million). Clearly, guidelines on safety, which were based on tests done on the pure glyphosate, are meaningless and need to be revised. 
February 2010 in Clinical Toxicology the article “A prospective observational study of the clinical toxicology of gylphosate-containing herbicides in adults with acute self-poisoning” looked at 601 patients poisoned by glyphosate. 19 of them died. Past studies have shown as little as a cup of this supposedly harmless chemical can kill you. Does it really make sense that we now pump 100,000 tons or 200 million pounds of this chemical every year into our environment? 
I include here a few graphs since a picture sometimes is worth a thousand words. (embeded in the articles):
2. Royal Society of Canada (2001) Elements of precaution: recommendations for the regulation of Food Biotechnology in Canada; An Expert Panel Report on the Future of Food Biotechnology. January.