As Scarecrow reported on Saturday, BP told EPA it would not switch from Corexit to another less toxic dispersant. BP admits that five approved dispersants are less toxic than Corexit; it dismisses four of those because the manufacturers cannot get enough product in place immediately.

BP does not have a stockpile of the other dispersants that meet the criteria in the May 19th Directive [of being less toxic], and the manufacturers tell us that they cannot produce the requested volume for 10 to 14 days or more.

So what about the fifith dispersant, Sea Brat #4, which is both less toxic and–BP tells us–and which BP has 100,000 gallons in its inventory? BP explains that Sea Brat #4 may degrade into an endocrine disruptor.

Sea Brat #4 contains a small amount of a chemical that may degrade to a nonylphenol (NP). The class of NP chemicals have been identified by various government agencies as potential endocrine disruptors, and as chemicals that may persist in the environment for a period of years. The manufacturer has not had the opportunity to evaluate this product for these potential effects, and BP has not had the opportunity to conduct independent tests to evaluate this issue either. BP learned of this issue after it applied to use Sea Brat #4 at the incident site.

With this additional information in hand, we believe it would be prudent to evaluate the potential NP issue more carefully before EPA or the FOSC require Sea Brat to be used at the incident site, and in particular, before it is applied underwater near the ocean floor.

BP latches onto a reality of the great test tube that is our everyday environment to explain why it is not using a competitors product. And the concern about the effect of possible endocrine disruptors is real. Endocrine disruptors have been associated with a range of biological problems, particularly with normal reproduction and cancers.

But that sort of raises a larger point, doesn’t it? These chemicals have been approved for use by the EPA but haven’t been tested to see if they degrade into endocrine disruptors. Not only does that mean we can’t choose a less toxic dispersant in time of emergency. But it also means this stuff is already being used, with no clear idea of the consequences of its use.

Of course, all this doesn’t answer the other question: whether we should be using dispersants at all, or whether BP is using it just to hide the effects of the spill underwater.