This article is long and not the easiest to read, but packed with information.
Genetic engineering is based on an long outdated theory that says one gene makes one protein.
Basically, that means, that, even if you could change just the one teensy weensy part of the DNA that you want to, to introduce a new trait in a crop (such as frost resistance), that tiny change might do all sorts of things you did not intend, even by itself.
And you can’t change just one thing, though the biotech industry would still have us believe they can, even though they have known better for YEARS.
Here’s what’s at risk:
1) Our Environment
2) Our Health
3) Our Economy
You can read how in this article. If you want another source that is a little easier language, I highly recommend the book Seeds of Deception and/or the film Genetic Roulette, both of which cover a lot of this same ground. I have linked to them in other articles on this site.