Final answer:
The Tuskegee Syphilis Study, conducted from 1932 to 1972 by the U.S. Public Health Service, involved unethical experimentation on African American men, leading to later reforms in research ethics.
Step-by-step explanation:
The initiative that was initiated by the U.S. Public Health Service and lasted for 40 years is the Tuskegee Syphilis Study. This study began in 1932 and ended in 1972, involving 399 African American men with syphilis and 201 without the disease as controls.
The participants were deceived into thinking they were receiving medical treatment for 'Bad Blood', but in reality, they were not treated for syphilis at all, even after the discovery of penicillin as an effective cure in the 1940s. The unethical aspects of this study, including the lack of informed consent and the refusal to offer treatment once it became available, led to widespread public outrage and significant changes in research ethics guidelines.