As for toxicity, the EPA rates both products as either comparable in toxicity or 10 to 20 times more toxic than the 12 others on the list. This week, BP chief executive Tony Hayward told The Guardian newspaper that the amount was “tiny in relation to the total water volume” in the Gulf.
Reliance on dispersants, especially in response to a disaster on par with the 1989 Exxon Valdez oil spill in Alaska, is understandable, say environmental groups. What they don’t understand is why marine ecosystems are being sacrificed to save coastal habitats, a trade-off that wouldn’t be an issue if less toxic solutions were stockpiled.
Not enough is known about how the Corexit products will affect marine life, says Richard Charter, senior policy adviser for marine programs with Defenders of Wildlife, an advocacy organization in Washington. Not only is the size of the spill unique, but the Gulf environment presents conditions that EPA testing would not necessarily replicate in a lab.
“You now have a giant chemistry experiment being done in the Gulf of Mexico,” Mr. Charter says.
Dispersants in general are also unpredictable in this situation because it is uncertain where the molecules will travel and eventually settle, due to heavy tidal conditions and tropical storms, and what byproducts will form as a result.