Many people erroneously believe that the government deliberately infected the Tuskegee participants with syphilis, which was not the case. But the work of Wellesley College professor Susan Reverby recently exposed a time when U.S. Public Health Service researchers did just that. Between 1946 and 1948, Reverby found, the U.S. and Guatemalan governments co-sponsored a study involving the deliberate infection of Guatemalan prisoners and mental asylum patients with syphilis.

The study was intended to test chemicals to prevent the spread of the disease. The researchers attempted to infect their subjects both by paying for them to have sex with infected prostitutes and by abrading the skin on their penises and pouring cultured syphilis bacteria on the wounds.

Those who got syphilis were given penicillin as a treatment, Reverby found, but the records she uncovered indicate no follow-up or informed consent by the participants. On Oct. 1, 2010, Secretary of State Hilary Clinton and Health and Human Services Secretary Kathleen Sebelius issued a joint statement apologizing for the experiments.

7 Absolutely Evil Medical Experiments