ATLANTA -- Shocking as it may seem, U.S. government doctors once thought it was fine to experiment on disabled people and prison inmates. Such experiments included giving hepatitis to mental patients in Connecticut, squirting a pandemic flu virus up the noses of prisoners in Maryland, and injecting cancer cells into chronically ill people at a New York hospital.

Much of this horrific history is 40 to 80 years old, but it is the backdrop for a meeting in Washington this week by a presidential bioethics commission. The meeting was triggered by the government's apology last fall for federal doctors infecting prisoners and mental patients in Guatemala with syphilis 65 years ago.

U.S. officials also acknowledged there had been dozens of similar experiments in the United States - studies that often involved making healthy people sick.

An exhaustive review by The Associated Press of medical journal reports and decades-old press clippings found more than 40 such studies. At best, these were a search for lifesaving treatments; at worst, some amounted to curiosity-satisfying experiments that hurt people but provided no useful results.

Inevitably, they will be compared to the well-known Tuskegee syphilis study. In that episode, U.S. health officials tracked 600 black men in Alabama who already had syphilis but didn't give them adequate treatment even after penicillin became available.

These studies were worse in at least one respect - they violated the concept of "first do no harm," a fundamental medical principle that stretches back centuries.

"When you give somebody a disease - even by the standards of their time - you really cross the key ethical norm of the profession," said Arthur Caplan, director of the University of Pennsylvania's Center for Bioethics.

Some of these studies, mostly from the 1940s to the '60s, apparently were never covered by news media. Others were reported at the time, but the focus was on the promise of enduring new cures, while glossing over how test subjects were treated.

Attitudes about medical research were different then. Infectious diseases killed many more people years ago, and doctors worked urgently to invent and test cures. Many prominent researchers felt it was legitimate to experiment on people who did not have full rights in society - people like prisoners, mental patients, poor blacks. It was an attitude in some ways similar to that of Nazi doctors experimenting on Jews.

"There was definitely a sense - that we don't have today - that sacrifice for the nation was important," said Laura Stark, a Wesleyan University assistant professor of science in society, who is writing a book about past federal medical experiments.

The AP review of past research found:

-A federally funded study begun in 1942 injected experimental flu vaccine in male patients at a state insane asylum in Ypsilanti, Mich., then exposed them to flu several months later. It was co-authored by Dr. Jonas Salk, who a decade later would become famous as inventor of the polio vaccine.