Large corporate interests like Monsanto (the folks who brought us Agent Orange and PCB's) are altering genes, the building blocks of life, by splicing together genetic material from one species into another and creating new organisms that never existed before. Bits of a fish gene have been added to a tomato's. Potatoes are being grown with pesticides built into each cell.
Nobody knows what may happen when these mutant organisms are set loose in the environment. And nobody knows what these new foods will do to our bodies and our health.