A study conducted by Temple University and Pennsylvania State University on the Deepwater Horizon oil spill, has discovered that the chemical dispersants used to clean the oil are more toxic to cold-water corals in the Gulf of Mexico than the oil itself. The dispersants had previously been used on surface waters, but following the 2010 spill were applied at depth. Seven million liters of dispersant were used to clean up the approximately five million barrels of oil. The dispersant is toxic to corals at much lower concentrations than oil. Erik Cordes, Biology professor at Temple said, "Applying the dispersants at depth was a grand experiment being conducted in real-time."