Dishwashing in the Gulf (part 2)

Today, the U. S. Environmental Protection Agency announced that it would require BP to use a less toxic (and more effective) chemical dispersant than the brand used so far. I wish, I wish, I'm always wishing for these actions to sparkle with government intelligence and initiative.

But it's obvious that the EPA was responding to pressure created by media reports, starting with a first class piece of research from Greenwire and by resulting Congressional inquiries. In fact, the EPA appears to have stood passively by while BP dumped more than half a million gallons of the chemical dispersant Corexit into the Gulf, despite the fact that it had been banned by the UK. And despite the fact that the agency's own internal analysis showed that this particular brand was not only more toxic but less effective in cleaning Gulf crude oil than others readily available.

Further, our federal regulators have done little - let's say nothing - to provide the rest of us with any reasonable information for assessing the chemical experiment no ongoing in the gulf. As I wrote in an earlier post (Dishwashing in the Gulf), Nalco, the company that makes Corexit, has made public limited health data by posting a list of the three primary compounds in their formula.

The first, 2-Butoxyethanol, was actually removed from the latest formula due to human health concerns. But in its hurry to start breaking down the oil, BP used thousands of gallons of this older formula, stockpiled and easy available. Most of the dispersant, though, has been the newer formula - which has depressingly resulted in us knowing less about what's in the mix. The only specifically named compound on the hazard list for the "new" Corexit is propylene glycol, which is not really that toxic but raises concerns because it's known to consume oxygen as it interacts with oil, posing a serious risk to aquatic species.

The company's safety data also cites a "proprietary sulfonic acid" but this is a basically meaningless statement if one is trying to determine risks to the environment, wildlife or people.

Oh, sure there's a vast quantity of information out there about sulfonic acids, which are used in aa array of industrial and researchl applications. For instance, some are used as buffering agents - meaning they help maintain a healthy pH balance - in cell cultures used in biomedical research. Others turn up in everything from laundry detergents to pesticides. So the the toxicity range is, well, large. Nothing to speak of in compounds used to maintain cell cultures. Lots to speak in some industrial formulations: Perfluorooctane sulfonic acid, for instance, which has been used in everything from fire-fighting foams to stain repellent formulas is has been linked to immune damage in animals and death in aquatic species.

And in chemical dispersants? Well, according to the Environmental Working Group, the mysterious sulfonic acid in this case appears to be the active ingredient in breaking apart the oil. But Nalco reports that, nevertheless, its particular formula has not undergone thorough toxicity testing.

Remember my wish for regulators who display intelligence and initiative? Maybe it's a little late to ask for that in this case. But how about informative?. If our government cannot take the basic steps to protect us from risky materials, it make an effort to educate us on what the risks are. And since I'm going for alliteration here how about adding this word to the list: immediately.


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I can't imagine any reason they would use perflurooctane sulfonic acid in an oil spill dispersant. It likely costs at least an order of magnitude more than hydrocarbon sulfonic acids (maybe two) and wouldn't work any better for crude oil dispersing (it would probably work less well).

The bad part about it is not the sulfonic acid part but the perfluorinated part which makes it not metabolizable and extremely resistant to degradation by any method.

The reason it is used in fire fighting foam is because it is incompatible with hydrocarbons. If you are fighting a hydrocarbon fire, you want a foam that can float on top of the hydrocarbon and prevent access to air and flames. A foam made with a hydrocarbon surfactant will be less stable than a foam made with a fluorocarbon surfactant.

Hydrocarbons consume O2 when marine bacteria metabolize them. The dispersant is present at a tiny fraction of the amount of the oil. There are some reports that the gas content (methane) of this spill is very high. Methane will dissolve in sea water at that pressure and there are bacteria which can oxidize that methane while reducing the sulfate in sea water to H2S. If that starts to happen on a large scale, there will be very large kills of everything except sulfate reducing bacteria.

I can't imagine it either, actually. The sulfonic acids that looked most probably to me for this job were alkyl and alkylaryl sulfonic acids, which don't carry nearly the baggage (as you point out) as perflurococtane sulfonic acid. I used the example only to make the point that to just say "sulfonic acid" is basically meaningless in assessing toxicity. Some are bad actors (these would also include formulas that include benzene or toluene, for instance) and some are pretty benign.
We - and by we, I mean the general public, especially people living on the Gulf coast, and also environmental scientist - should be told more.

I grew up in NJ, and lived about a mile downstream from a sewage treatment plant. I remember back in the 1960's when synthetic detergents first came out and they were not biodegradable and gigantic amounts of foam would accumulate at the bottom of a very small waterfall. They first synthetic detergents used sulfonate branched chain hydrocarbons. Bacteria couldn't degrade them, so they accumulated. They pretty quickly switched to straight chain hydrocarbons and the problem went away.

The "propriatary" sulfonic acid is probably a mix of some low-grade hydrocarbon that is sulfonated. It probably isn't a pure compound. It is probably similar to the crude oil in terms of what it is. They can't use stuff that has too high a molecular weight or it would be a solid and wouldn't dissolve. It is probably something like charcoal lighter fluid that is treated with sulfur trioxide. Charcoal lighter fluid might be a higher grade of hydrocarbon than what they use.

Thanks - that's actually as good an analysis as I've read so far and doesn't raise all kinds of red flags for me. Emphasizing that it would be smart if our regulatory agencies - or even, although less likely, BP, would provide some similar straightforward information. Thanks for writing!

I think the problem is marketing. If they said what was in it, the customer could make it themsleves at 1/10 the cost. For a small spill it is cheaper to buy it than to make it, but for a BP sized spill it would be cheaper for BP to make it themselves.

I am pretty sure that BP makes every single one of the ingredients.

I wouldn't be surprised. It's a pretty incestuous business. Did you see this NYT story about concerns over whether labs doing analysis are really independent from BP's influence?