Concerns about genetically modified tomatoes:
In addition to the gene that retarded the ripening process, GM tomatoes had a secondary genetic modification in the form of a gene segment conferring resistance to the antibiotic Kanamycin. This marker was added to help identify GM plants - it had no other function.
Researchers were concerned that there may be a danger with this genetically modified food. Their concern was that if the Flavor Savr was commercially grown, environmental bacteria might uptake the antibiotic-resistant gene segment, develop a resistance to Kanamycin and then develop resistances to other antibiotics as well. If this happened, it would certainly spell trouble for human health.
Several studies in the 1990's showed that lab rats had developed stomach lesions after eating the GM tomatoes. However, many scientists have questioned the methodology and worth of these studies.
Consumer concerns about the dangers of genetically modified organisms surfaced after the outbreak of the Mad Cow Disease in Europe. While there may certainly be some advantages of genetically modified foods, they still get a bad press, largely due to concerns over their safety. To date there haven't been any studies that have demonstrated any long term negative health affects of genetically modified foods.
However, consumer confidence remains low. Shoppers need and want to know what they're buying. When companies cannot or will not label genetically modified foods, they are viewed with a great deal of mistrust by the general public. Media headlines about so-called "Frankenstein foods" exacerbate their fears.