Recently, the taxpayer supported National Academy of Science came out with a book looking at biotechnology in the food supply. The book:
Mendel in the Kitchen: Scientist's View of Genetically Modified Food
by Nina V. Federoff and Nancy Marie Brown
352 pages, 6 x 9, 2004
The book can be found at http://www.nap.edu/catalog/11000.html.
This book is worth checking out for its clear descriptions of how cross-genetic foods are created. Overall, my layman's feeling is that the author is dismissive of safety concerns even in the absence of testing, but the book is still interesting. Putting salmon genes in tomatoes to prevent freezing still seems like a bad idea to me. On the other hand, there are legitimate uses for genetic engineering, like greater drought resistance.
Like all books in NAS cataloged may be read on-line,or ordered in print or a regular PDF file. For someone looking for relatively balanced views of science issues, the NAS web site is a good place to start. That web site is http://www.nap.edu.