New research from the University of Guelph says the survival of young salmon are at risk from a diluted bitumen spill even if the fish later end up in clean water.

Ten things an unpublished government-commissioned study found remain unknown about the effects of oil and oilsands products in rivers, lakes and oceans.

Critics say the federal government has been trying to hide legitimate concerns about the consequences of oilsands pipelines by keeping a report under wraps on the possible environmental threats posed.