Which is Worse? Washing Laundry or Spraying Corexit 9500 Dispersant on Oil Spills?

Image: Flickr, Deepwater Horizon Response

A lot of the questions surrounding the response to the gulf oil spill address the chemicals being sprayed onto the gulf and pumped out underwater to disperse the spilled oil. These dispersants are intended to break the oil up into smaller bits, which can sink into the water and get eaten up by microbes there. Along with questions about whether "out of sight, out of mind" is really better, there are serious concerns raised about depositing huge quantities of dispersant chemicals into the natural environment. So we got to wondering: how bad is this dispersant? And how does it compare to the chemicals we use every day in our laundry detergents, cosmetics, and other common products?

COREXIT� EC9500A and COREXIT� EC9527A
According to Nalco's Material Safety Data Sheet for COREXIT� EC9500A, the Corexit 9500 A dispersant which is being sprayed by the millions of liters from Hercules Transport planes flying over the Deepwater Horizon spill consists of 10 - 30 % light, hydrotreated petroleum distillates; 10 - 30% of a trade secret organic sulfonic acid salt; and 1 - 5% of propylene glycol.

The underwater dispersant, COREXIT� EC9527A, contains 30 - 60% 2-Butoxyethanol instead of the petroleum distillates, along with the same two ingredients found in the Corexit 9500 A.

The full formulation, without any secrets held back, has been disclosed to government authorities, who are overseeing the use of dispersants in the spill response. But what do we know about the chemicals which are disclosed publicly?

Light, Hydrotreated Petroleum Distillates
Sounds a little crazy: spraying petroleum on leaking petroleum -- that should help? But in fact, light, hydrotreated petroleum distillates is quite different from "petroleum." The chemical category represents a "success" in taking by-products from other production processes and turning them into product...waste minimization in other words. This chemical is named by the process that creates it, rather than a chemical name, because it is a complex and variable mixture of hydrocarbons created by specific types of processes.

Tracking the volumes produced is tricky, because this stream is reported as part of the "fuel oils category," which has 1.6 billion kg per year in the USA alone. The light, hydrotreated petroleum distillates are part of the "other" category, which consists mainly of four types of streams and constitutes 9% of the fuel oil category products. So call it 25% of "other" and you come up with 400 thousand tons of light, hydrotreated petroleum distillates per year in the US. Industrial uses include fuels and solvents. Typical household uses include air fresheners, lubricants and car care products.

The OECD is still in the information gathering and data review stage of assessing these chemicals under the high production volume (HPV) chemicals program. But results published by various regulatory authorities show that this ingredient can be harmful in the aquatic environment (harmful is officially defined as causing effects at a level that is below "toxic"). It does not biodegrade readily, but it does not bioaccumulate readily either.

2-Butoxyethanol
2-Butoxyethanol (2-BE) is used mainly in paints and surface coatings (predominantly water based decorative and industrial products), followed by cleaning products (especially degreasing or multi-purpose products) and inks, and as a solvent in hair dyes. The 2-BE in these products is basically all relased to the environment, by evaporation in the case of surface coatings and to wastewater streams in most other cases. The OECD estimates that 200,000 to 500,000 tons of 2-BE is produced annually.

The chemical does not bioaccumulate and biodegrades rapidly in sewage treatment plants, and therefore can be commonly found in cleaners advertised as "green". However, there is documented occurrences of groundwater contamination ocurring when 2-BE is disposed of in landfills, where it cannot biodegrade as effectively.

It causes reversible irritation to eyes and respiratory tract upon exposure. 2-BE is not considered toxic, but it is ranked officially as "harmful" by European Union authorities. 2-BE can be absorbed through the skin. It is a member of a chemical family known as "glycol ethers," and some of the fears about 2-BE may arise because its smaller siblings 2-methoxyethanol and 2-ethoxyethanol have been shown to cause testicular degeneration. Substantial testing of 2-BE has not shown such effects; in fact, it shows effects on fertility and reproductive toxicity only when exposure levels are so high that other toxic effects are triggered. With sufficient studies completed that the OECD closed demands for additional testing, there is no evidence supporting carcinogenic nor mutagenic effects.

The first critical effect of 2-BE is haematotoxicity, the destruction of red blood cells. Humans are less susceptible to this effect than other species (for example rats are ten times more sensitive than humans). Because 2-BE is quickly eliminated (half-life in blood of 40 - 80 minutes, and half-life until excretion in urine of 3 - 6 hours), there is a low risk of enough of the chemical building up to reach haematotoxic levels.

Propylene Glycol
Propylene glycol is used mainly in resins (26%) and antifreeze or de-icing fluids (22%), but the US EPA estimates that 18% of the PG used in the US goes into food, drug, and cosmetic uses. Other uses include liquid detergents (11%), pet food (3%), and tobacco (5%). Production in the US and Europe alone exceeds 920,000 tons.

Propylene glycol is so non-toxic that you could eat at least 2 to 13 grams per kg of body weight per day with no observable effects. (Author's note: a reader has asked us to point out that Ethylene Glycol is also often used in antifreeze products. Ethylene Glycol is poisonous, possibly deadly.)

Organic Sulfonic Acid Salt
The real problem with knowing how hazardous Corexit products might be lies in the confidentiality protection granted to the manufacturers of chemical products. The main active ingredient of the Corexit is given only by its generic chemical name.

Sulfonic acid salts are widely used by the detergents industry. Alkylbenzene sulfonic acids are the most common members of this chemical family, beloved for their low cost, detergent performance, and biodegradability. Here we are talking about truly huge quantities of chemicals produced, used and disposed of annually. For example, over 1 million tons of linear alkylbenzene sulfonic acids (LAS) are produced annually. 78 - 97% of that goes straight into the environment via the wash cycle.

These chemicals are regarded as being of low concern, because they biodegrade very rapidly, especially in wastewater treatment plants. This facade of eco-friendliness masks a more significant issue: many organic sulfonic acid salts are fairly toxic to the aquatic environment, and can be especially disturbing to cell membranes of single-cell and other simple creatures. A 2005 study of dispersant use (German, pdf) for promoting biodegradation in marine oil spills found that the toxic effects of the dispersants may deter the very organisms that are trying to eat up all that nasty spilled oil.

So How Does the Oil Spill Compare?
The fact is that we are running a huge ecological experiment in the Gulf. But the amount of chemicals going into the environment, even from the direct application of chemicals to combat the oil, is dwarfed by the amount of chemicals used by consumers and industry every day. As the questions first arose about the ecological safety of the dispersants BP is using, reports indicated that over 2.2 million liters of the sprayed dispersant and over 300 thousand liters of the underwater dispersant had been released. Even assuming the sulfonic acid salts in these dispersants, probably the ingredients of most concern, are present at the higher end of the range Nalco discloses, one could project that a couple thousand tons of active chemical will be used by the end of this operation.

Compare that to the millions of tons of these chemicals that go into our wastestreams every year from the normal everyday products we use. Even if you assume, optimistically, that 100% of this chemical waste goes to waste treatment at 99.9% efficiency, our ordinary use of these chemicals rivals the BP oil spill treatment every year. Is it time to take the anger at the oil spill and turn it into energy for change? It is not only accidents we need to prevent...

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