Experimental drugs and other treatments may be prescribed for patients who are not informed that the full effects of their treatment are not known and who are not asked for their consent to take part in an experiment. Such patients are generally those who can be most easily pressured into accepting unknown and in some cases unwanted treatments, such as the poor and uneducated. Reports of unethical experimentation have been made particularly with regard to contraceptive methods and methods of induced abortion.
The now infamous Tuskegee syphilis experiment in Alabama, was conducted on around 600 poor rural black men by the US Public Health Service. The experiments begun in 1932, and continued for 40 years, until the news finally broke in 1972 in the national press.
All but one of eighteen hospital patients knew they were being injected with low-level plutonium by US government researchers after the element was first produced by the Manhatten Project in the 1940s.