""These cell lines are now more than three generations removed from their origin, and we have not used any new tissue to produce these vaccines," the company added in its statement. To say that the vaccines contain a significant amount of human fetal tissue, as some objectors to the vaccines claim, is misleading, stressed Dr. Paul Offit, the director of the vaccine education center at the Children's Hospital of Philadelphia. "There are perhaps nanograms of DNA fragments still found in the vaccine, perhaps billionths of a gram," he said. "You would find as much if you analyzed the fruits and vegetables you eat." And to remove human fibroblast cells entirely from vaccines is out of the question, Offit explained, noting they are necessary because human viruses don't grow well in animal cells. "They have also been tested for safety and the fetal cells can go through many more divisions than most other cells before dying," he said."