The Big Ag business with mega size farms is looking for ways to change growing practices to increase profit. One way they discovered was to genetically modify genes in plants to grow faster, survive longer, and stand up against insects better needing less chemical sprays. Something nature has trouble accomplishing on her own. ref ref
They have succeeded in some of these areas by various degrees. Scientists splice a foreign gene from a different plant or animal or fish into the crop plant seed to achieve some of these factors in the newly created hybrid plant. But one area, testing these GMO crops for safety has proven to be an enigma. ref In fact Monsanto, developer of the GMO process, says they don't need to test the GMO plants since it is assumed the results would be the same as the testing showed for the original crop plant as nature made it. Plus Monsanto is preventing Scientists other than their own to even study these new GMO seeds and plants. Why if they are so safe? Even nature puts toxic elements in plants to help them repeal insects. Monsanto claims the new modified gene material would be destroyed during the human digestive process and this would render it a non issue. This has now been discovered to not be entirely true as a Scientist has discovered this new GMO built protein in human blood. ref
Education: Here is everything the US Government health agencies have looked into about GMOs.
This concept is going to take some understanding to fully comprehend what is happening. But the most important point, if GMO crops prove to be dangerous, IT IS ALREADY TOO LATE SINCE ONCE A GMO CROP IS PLANTED, throught the air, the new gene code DNA MIGRATES INTO AND KNOCKS OUT THE NATURAL PLANT GENES GROWING AROUND IT. ref ref
This changes the GMO Game
RNA MODIFIED MATERIAL FROM GMO RICE PLANTS HAS JUST BEEN FOUND IN HUMAN BLOOD. The new GMO created proteins SURVIVED THE HUMAN DIGESTIVE SYSTEM. THIS WAS NOT SUPPOSE TO HAPPEN ACCORDING TO MONSANTO'S SCIENTISTS. And once in the body, this new GMO protein was found to influence LDL cholesterol removal from the blood. This is a first. Since this is a rather new discovery, all past safety studies will now need to be re-evaluated, and new testing research generated.
Does this mean the Monster is out for GMO crops? Well, maybe not quite yet. BUT, the prudent oourse with the state of current knowledge may be to take steps to minimize exposure. HOW DO YOU KNOW WHICH FOODS are Genetically Modified (GMO)? ref
In the USA, Stay away from alfalfa, corn. soy, Canola oil, and Hawaiian Papayas. 
WHY are GMO's potentially dangerous to humans (and good bugs) even though Monsanto thinks they are safe?
To make a plant resistant to a certain plant eating insect, Scientists find a gene from another source that when spliced into the plant DNA, builds a new protein. When the bug eats the plant, this new protein generates a pathway that kills the bug. The other bugs quickly learn not to eat that plant. Well, proteins are the agents often responsible for producing human allergies. These new proteins in GMO food could increase avenues to produce allergies.
Monsanto said this would not happen as these new proteins would be destroyed during digestion probably by stomach acids. Rather interesting that they thought the insects digestive system would take in or generate the new protein but not the human system. Well, as mentioned above, a Chinese research team has found this new RNA material measured in human blood that was used to genetically (miRNA) modify the plants DNA. Since this material has the possibility to interact with human DNA material, could it eventually build this new protein inside humans? Why have so many Countries worldwide banned GMO's? ref
WRAP UP
What do the Scientists in these other Countries know that Monsanto does not want you to learn?
Is Monsanto playing fair? Why do they prevent independent Scientists from testing their modified plant material? Why does the FDA and DOA go along with Monsanto's weak arguments and lack of scientific testing?
Is there past history of failed GMO crops? YES!
They did not live up to expectations. Crop yields begin to shrink and costs were not reduced, they escalated in some cases. Farmers had to purchase new GMO seeds from Monsanto each year because recovered seeds from the current crop would produce hybrids of lower quality in future yields.
How do the beneficial insects fair? Could the die off of Bees prove associated?
THERE IS GROWING CONCERN THAT SOME DISEASES NOW RAPIDLY INCREASING IN CHILDREN MIGHT BE RELATED. They are at a greater risk of showing effects from GMOs than adults due to their smaller body size and increased metabolism rate. ref
Are there examples of known deaths associated with GMO tinkering?
YES, 37 people died and countless scores of people have various degrees of body damage for the rest of their lives due to the contamination of the supplement, Tryptophan. These deaths were the result of a new GMO bacteria used in the production of Tryptophan that formed a mutation which remained in the product. There are other products such as insulin ref and vaccines ref that use GMO bacteria in their production, too. They are now studying the long term safety of these products? Food crops are now being Genetically Modified to increase nutrient levels to help prevent diseases where proper food sources are limited by costs.
Just like other issues, Benefits with Risks. But the margin for error with GMO's, could be zero. The point of return to normal nature has now long been passed since GMOs have been unleashed into the wild and are no longer controllable. The human race is at the mercy of existing GMOs for whatever they might unleash in the future on humans and the environment. Limiting your intake and exposure is now your only known precautionary and defensive weapon. At least until longer term scientific reaearch settles these issures.