EPA Testing of BP Oil Spill Dispersants - Nearly Equal Toxicity

The ongoing BP oil spill (though I'm not sure "spill" is the right word for an open tap of oil gushing into the ocean uncontrolled) has stimulated a lot of interest in the toxicity of the chemical dispersant being used. Concerns were that the one BP is using, Corexit, is more toxic and less effective than alternative chemicals. Given that BP has already dumped over 1.6 million gallons of Corexit into the ocean, the question is not insignificant.

EPA initially ordered BP to identify a less toxic brand of dispersant, but BP indicated that "they were unable to find a dispersant that is less toxic than Corexit 9500, the product currently in use." It's unclear how hard BP tried to find an alternative given that they had millions of gallons of Corexit stockpiled and none of any alternative. It's also cheaper. They are also busy trying to stop the flow of oil into the Gulf and thus don't really have the resources at the moment to do a research project. Which, of course, begs the question as to why wasn't this research carried out already so that stockpiles of the most effective yet least toxic chemical dispersant could be ready for the catastrophe that many suggest was inevitable?

Given BP's inability to find an alternative, EPA decided to test a variety of dispersants with the intention of telling BP that they had to switch. But after the first round of toxicity testing, the results seem to show that they are all about the same.

EPA is not yet prepared to tell BP to switch to another brand of oil dispersant for use in response to the ongoing spill in the Gulf of Mexico, after releasing a first round of toxicity testing data that showed all available varieties had roughly similar toxicological properties. EPA did determine that "none of the eight dispersants tested, including the product in use in the Gulf, displayed biologically significant endocrine disrupting activity."

The toxicity of the dispersant is a tradeoff, and all of the chemicals appear to be less toxic than the oil itself. However, one drawback is that the testing is being done only on the individual chemicals; it's unclear whether there would be enhanced, or decreased, toxicity once the dispersant is mixed with the oil. Given that different fractions of the crude oil degrade at different rates (and react with the chemical dispersant differently), there are a lot of uncertainties that remain. EPA will continue to do testing and report their findings on the Response web site.

Meanwhile, problems with the cap have resulted in even more oil gushing into the Gulf and the first hurricane of the season - Alex, now a Category 2 - will pass well below the spill site, though surge effects from it will likely push more oil onshore. Hurricanes also will affect the ongoing activities in the Gulf. And this is expected by hurricane forecasters to be a particularly active season.

Let's hope they're wrong.