In my Environmental Science class, we talked about GMO crops and such. We discussed that they could potentially be dangerous, but there wasn't enough studies to confirm it. If these tests are correctly conclusive, this could open a whole new branch of tests leading to the discovery of possible threats in our foods. But like any GM crops, they also disturb the status quo of nature, creating pollution, affecting other animals (i.e. rats, as you stated). They can also become super-crops (hard to rid of, and possibly invasive), ruin the integrity of native ancestral races of crops, might breed with wild relatives.
Not only does this matter concern our health or the environment, but this has a major impact on politics. Production, approval, and distribution of GMO should all follow certain standards. I believe more testing should be done about the use of GMO before they start harming us. I also think that, whether they do or they don't keep producing GM crops, they should mark them as so in big labels or were it is easily seen that the product uses GM material. This would at least make people think twice before they buy something involving GMO.