HELEN BRANSWELL
The Canadian Press

U.S. and Canadian regulatory rules allowed companies to conduct "secret science" that jeopardized the lives and health of hundreds of people who took part in clinical trials for a human blood substitute, even though earlier tests had shown the existing products were dangerous, researchers reported yesterday.

Companies were not required to publish the findings of their trials, leaving research ethics boards that were assessing applications for additional trials - and people being asked to participate in them - in the dark about the fact the products elevated the risks of death and of having a heart attack.

A review of all the available literature on the trials - published online yesterday by the Journal of the American Medical Association - shows that people who received hemoglobin-based blood substitutes in clinical trials were 30 per cent more likely to die and faced a nearly threefold increased risk of heart attack.