According to 16 clinical trails analyzed by researchers, artificial blood has raised the death risks by 30 percent and almost tripled the odds of heart attacks and these same researchers say U.S. regulators should have stopped the studies eight years ago.

Five trials involving substitute blood products are ongoing, and a new one is about to begin, the researchers reported.

The researchers also reported in the Journal of the American Medical Association, said the FDA in 2000 received data on individual studies showing increased risks that should have triggered suspension of testing until a large-scale analysis. Now they demand taht  the agency end all trials and Congress should review rules forcing the FDA to keep information on new products confidential for competitive reasons.

Some finished studies still aren’t public. Five trials are ongoing internationally, in places including the U.K., and at least one more is planned.

Developing a blood substitute that requires no refrigeration, has a long shelf-life, and doesn’t cause infection could prevent deaths from blood loss, the researchers wrote in their article. But many lawmakers and consumer groups have criticized the FDA’s oversight of research after reports of elevated heart risks prompted the withdrawal of painkiller Vioxx in 2004 and stronger warnings on GlaxoSmithKline Plc’s diabetes pill Avandia last year. The Government Accountability Office said it will investigate whether the agency approves drugs without enough evidence of safety and effectiveness.

The authors of the study theorized in their study that the blood products may cause harm because manufactured hemoglobin isn’t part of a red blood cell, and can scavenge nitric oxide, resulting in decreased blood flow and the formation of clots.

None of the trial results were published immediately after the studies were completed and the FDA reviewed each separately.