2/2/15, 2:06 PM Business & Financial News, Breaking US & International News | Reuters.com Page 1 of 2 » Print This copy is for your personal, non-commercial use only. To order presentation-ready copies for distribution to colleagues, clients or customers, use the Reprints tool at the top of any article or visit: . U.S. researchers broke rules in Guatemala syphilis study Tue, Aug 30 2011 By Alina Selyukh WASHINGTON (Reuters) - U.S. government researchers must have known they were violating ethical standards by deliberately infecting Guatemalan prison inmates and mental patients with syphilis for an experiment in the 1940s, according to a presidential commission. The U.S.-funded research in Guatemala did not treat participants as human beings, failing to even inform them they were taking part in research, as was the case for a similar study in the United States, the commission said on Monday. The United States apologized last year for the experiment, which was meant to test the drug penicillin, after it was uncovered decades later by a college professor. President Barack Obama's Commission for the Study of Bioethical Issues investigated the syphilis experiment and discussed its key findings in Washington on Monday. A final report is due in December. "They should shock the conscience not in spite of their medical context, but precisely because of it," said the commission's chairwoman Amy Gutmann, president of the University of Pennsylvania.