'Fog Of Research' Clouds Study Of Oil's Effects In Gulf, NPR, February 24, 2011:
[F]ederal government's scientists are doing some research now, but most of that lies beneath a veil laid down by the Oil Pollution Act, which calls for research in order to assess damages against those responsible for oil spills. Because that may involve litigation, that research is largely secret.
"Dozens and dozens of studies are in the field," [Stan Senner, the director of conservation science with the Ocean Conservancy] says, "thousands and thousands of samples have been gathered but that work is largely being held confidential."
Listen to the report here.