A researcher studying the infamous Tuskegee experiment discovered that American researchers had performed similarly immoral medical studies in Guatemala in the 1940s.
In an attempt to figure out whether penicillin could prevent, as well as cure, STDs, researchers affiliated with the U.S. Public Health Service, the National Institutes of Health, the Pan-American Health Sanitary Bureau (now the Pan American Health Organization) and the Guatemalan government exposed almost 700 Guatemalans to syphilis and gonorrhea without their consent—both through direct inoculation and via hiring of infected hookers.
It's unclear whether any of the subjects ever received treatment to cure the diseases they were unknowingly given.
Secretary of State Hillary Clinton and Health and Human Services Secretary Kathleen Sebelius issued apologies for incident today.