Posted Tuesday, August 30, 2011 --- 7:05 a.m.

ATLANTA (AP) -- New details are being disclosed about one of the darker episodes of medical research in U.S. history -- experiments on humans in the 1940s.

A presidential panel on Monday described details of U.S. medical experiments done in Guatemala, including a decision to re-infect a dying woman in a syphilis study.

The panel members say the new information indicates that the researchers were unusually unethical, even in the historical context of a different era. They say the research itself was bad even by 1940s standards.

Panel member Anita Allen says the researchers put "human decency a far second."

The Presidential Commission for the Study of Bioethical Issues says that from 1946-48, the medical research -- paid for by the U.S. government -- involved deliberately exposing people to sexually transmitted diseases.

The researchers apparently were trying to see if penicillin, then relatively new, could prevent infections.

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