Caplan: No word from Bachmann

Bioethicist Art Caplan said his challenge to Republican presidential candidate Michele Bachmann for proof that a vaccine to prevent cervical cancer caused mental retardation ended without Bachmann acknowledging it.

Caplan, director of the Center for Bioethics at the University of Pennsylvania, offered to pay $10,000 to a charity of Bachmann's choice if she could find such a person by noon Thursday. Bachman said in television interviews on Sept. 13 that a woman told her that the shot, usually given at age 12, triggered mental retardation in the woman's daughter.

The day before, Bachmann chastised Texas Gov. Rick Perry during a Republican debate for requiring girls in his state to get Merck & Co.'s Gardasil vaccine to ward off a sexually transmitted disease that can cause cancer.

Caplan said the statements by Bachmann, a congresswoman from Minnesota, may cost lives by keeping parents from vaccinating their daughters.

"I never heard back from her or her staff, but I know she knew about it since she was asked about it by reporters," Caplan said in a conference call Thursday. He encouraged people to donate to the Vaccine Education Center at the Children's Hospital of Philadelphia.

Neither Bachmann nor Alice Stewart, her spokeswoman, returned calls or e-mails from Bloomberg.