"As arguments rage over how to clean up the Deepwater Horizon oil spill, an examination of toxicity tests reveals flaws in the data used to determine the safety of dispersants.

The US Environmental Protection Agency and BP have locked horns over the toxicity of the dispersants being used to break up the oil spewing from the Deepwater Horizon well. Now, New Scientist has learned that huge variability in the safety test results submitted by different manufacturers makes it very difficult to judge which of the available dispersant chemicals poses the least threat to marine life.

"It screams to me that I can't make a judgement on any of these data," says Carys Mitchelmore, a toxicologist at the University of Maryland's Chesapeake Biology Laboratory in Solomons, and co-author of a 2005 National Research Council report on the use of oil dispersants.

The EPA commissioned a new round of tests in late May, but it remains unclear when these will be completed."

Peter Aldhous reports for New Scientist June 16, 2010. [2]