Part of the problem is that genetically modified foods are largely benign, and most of the hysteria about them come from junk science experiments designed to show how evil GM foods are. People have been genetically modifying foods pretty much since agriculture was invented, primarily by cross-breeding trial and error and as a result of selective breeding. Now the trial and error is reduced to a large degree, and people freak out in some cases. In some cases they're correct in freaking out, but not in all or even most cases.
The problem is with the willingness of those in charge, and the desire of companies like Monsanto, to get these things onto the market without the thorough studies. The risks of genetically modified foods, most of them are low. But we still really don't know that for sure. The ones who are modified to be resistant to to certain pesticides aren't going to be much of a problem with human consumption, because of how they are modified. Neither are the ones modified for longer shelf life, delayed ripening or for larger size.
I do have a concern about the ones that are modified for insect resistance, the ones that are modified to create their own bacterium (BT) that produces the identical toxin used in normal insecticide crop spraying. With crop spraying, the insecticide remains primarily on the outer surface of the foods, but the GM versions have the BT toxin thoroughly interspersed throughout the plant, and no amount of washing will get rid of it. What kind of long term or cumulative effect do these toxins have on those who eat them?
It's well known the problems of giving cows growth hormones to produce more milk or to grow larger and heavier, since those hormones are passed right on to whoever consumes them. Milk loaded with female growth hormones can cause quite a number of problems to a developing fetus and to young children. All you have to do is look at Thailand and Brazil where they went nuts with milk production growth hormones for years, and you'll see an astoundingly high rate of "gender confused" people, almost all of them men who think they're women, which should come as no surprise since they've been sucking on female hormones ever since they were conceived.
Herbicide tolerance, disease tolerance, cold tolerance and other genetic modifications are not a problem, it's the pest resistance tolerance, and things like medicinal modifications that are troubling. Some of these modifications can really mess up an insect that eats them, and then something else eats that insect, and so on and so on right up the food chain where we then eat it. There are strains of GM corn that are not allowed to be fed to humans, but can only be used for cattle feed. And then we eat the cattle. Excellent.
