PHILADELPHIA (CBS) – A University of Pennsylvania researcher has issued a challenge to GOP presidential hopeful Michele Bachmann: back up your claim that the HPV vaccine causes retardation, and I will make a $10,000 donation to the charity of your choice.

Michele Bachmann said this week that a woman approached her, and said her daughter suffered from mental retardation after getting the human papillomavirus vaccine. Art Caplan, director of the Center for Bioethics at the University of Pennsylvania, wants proof.

“I said, ‘look, I’ll pay you $10,000 if you deliver that person who you say was made retarded by the vaccine, and I’ll give it to the charity of your choice. You pay me $10,000 if you can’t deliver that person in a week.’ It was basically saying ‘you don’t know what you’re talking about.'”

Caplan says the HPV vaccine is safe and saves thousands of lives each year. He says there shouldn’t be fear-mongering about vaccines by politicians when there are a large number of Americans, adults and children, who still don’t get the vaccines available to prevent many illnesses.

Reported by Kim Glovas, KYW Newsradio