Do we Know enough about Genetically Modified Foods?

http://www.grist.org/advice/possessions/2000/04/21/possessions-genetic/

This article is about how GMF's are produced. Specifically corn, potatoes and and cotton; they are made to produce their own pesticides. Other ways that genes are produced are by splitting genes and inserting them into other organisms.
Other interesting facts are that:
-squash and papaya can fight diseases (b/c of genes from a virus)
-specific hormone can boost milk production in cows
-Salmon has been modified to to use more of their own growth hormones so they can increase in size, thus making the world's Salmon population much larger.