Science On Dispersants Used In Oil Spills Is Murky

The EPA and BP have cited scientific studies to back their positions on oil dispersants. And while the EPA initially wanted BP to stop using dispersants altogether, it hasn't stopped the company from using them entirely. That may be because the science on the chemicals is pretty murky.

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As we just heard, both the EPA and BP have cited scientific studies to back their positions on oil dispersants. And we've heard that while the EPA initially wanted BP to stop using the dispersant altogether, it hasnt stopped BP from using it entirely. That may be because the science here is pretty murky.

NPR's John Hamilton joins us to sort through whats known and whats not.

Good morning.

JON HAMILTON: Good morning.

MONTAGNE: First, let's talk about the EPA. Does the agency really have strong evidence that the chemical dispersant BP is using is a bad choice?

HAMILTON: They do not have the strongest evidence. What theyve got, and what people have been arguing about, is there have been toxicity tests done on a small fish and this little, tiny shrimp. And mind you, these tests are done in a lab not in the ocean where these creatures actually live.

So, the test suggests that this dispersant they're using, Corexit, it will - it takes a smaller amount of it to kill these two particular organisms than some of the other products. But the problem with that - and I've asked a couple of scientists about this - the problem is the toxicity tests have been all over the map.

That is to say, when you look at how they average out, yes, it does seem to be more toxic, but you get wildly different results. And one scientist said orders of magnitude differ from test to test, and that tells you you really don't that much about the difference in toxicity of these different chemicals.

MONTAGNE: So, cutting dispersants in half, or maybe even a little more, how much difference would that make?

HAMILTON: Well, it certainly going to make some difference in where the dispersants go. What we can tell you about here, or what Lisa Jackson was talking about, is not spraying these dispersants on the surface of the ocean anymore. And what happens when you spray on the surface is it breaks up the oil and then that stuff starts to sink down through the layers of the ocean, right?

So, you're not going to have dispersant hitting sea creatures that live on the surface or near the surface of the ocean. Of course, they will be exposed to oil, which is far more toxic than the dispersants.

And so, you know, spraying may protect some things near the surface but they're still going to be releasing this stuff into the stream of oil coming off the ocean floor, and nobody knows what happens when you do that. This is really the first time. So, that's going to distribute maybe a more diluted form, but it's going to be all over the Gulf, because the stuff is coming up through 5,000 feet of water and has a chance to get into all the currents that take it everywhere.

MONTAGNE: And all the levels of sea life.

HAMILTON: All the levels.

MONTAGNE: The EPA is concerned that the dispersant will have long-term effects on the environment. What about that?

HAMILTON: Well, I've asked some scientists about that and they say, you know, that's a reasonable concern. The toxicity tests have, you know, extend over a few days. But when you put chemicals into the environment, often things are there for years. And one of the things that BP said was that one of the alternatives to Corexit is a product that breaks down - or part of it does -into a chemical known as an endocrine disrupter, a potential endocrine disrupter.

And we've heard a lot about these recently because if concern about plastic bottles. Things called BPA and phthalates and rubber. These are endocrine disrupters and the EPA is extremely concerned about endocrine disrupters. So, for BP to invoke this, is actually making a pretty good point.

MONTAGNE: Because they do what exactly? I mean, give us some examples of what possible harm might...

HAMILTON: Endocrine disrupters act...they're not like poisons, they're not like toxics. They don't make things die usually. What - they act like hormones. And so you can see generational changes, you can see sexual development of creatures changed, you know, things like that. Much more subtle signs.

MONTAGNE: And any other sorts of things we should, you know, be thinking about in terms of harm?

HAMILTON: The thing to remember is that dispersants take oil places it's not otherwise going. So, what that means is you bring oil, which is itself very, very toxic, to other places. So, when you put oil to the surface, you might bring oil to, say, eggs that are just beneath the surface. And so by not spraying on the surface you might protect them.

On the other hand, so now you're putting this into the column of oil coming off there and it's going to go far, far away. So, tiny creatures we don't even know about may be exposed and we have no idea what that's going to do.

MONTAGNE: Jon, thanks very much.

HAMILTON: You're welcome.

MONTAGNE: NPR's Jon Hamilton.

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