Chemical Dispersants Being Used In Gulf Clean-Up
Are Potentially Toxic
By Tom Philpott
07 May, 2010
Grist.org
We finally know the main two dispersants that BP and the U.S. government are using to treat the ongoing Gulf spill. Both, by their maker's own admission, have the "potential to bioconcentrate," and both have "moderate toxicity to early life stages of fish, crustaceans, and mollusks," according to a study by Exxon, the company that originally developed them. Their use may be the least-bad course, given the importance of minimizing oil's effect on coastal wetlands. But a little digging into the chemical makeup of these two substances, which are being dumped in vast quantities into the Gulf, reveals that they could potentially do far more harm than good, both to the Gulf and to humans who later eat from it.
As ProPublica reported Monday, information about dispersants is "kept secret under competitive trade laws." I've spent the last several days trying to confirm what many in the ocean-ecology and public health worlds seemed to know, but no one would say officially: that two different dispersants sold under the banner of Corexit were being used in vast quantities. The Corexit brand is owned by an Illinois-based company called Nalco, which entered the dispersant business back in 1994, when it merged with Exxon's chemical unit. (By 2004, Exxon had divested and Nalco was a standalone company, according to Nalco's company history.)
Last night I finally got my confirmation. A spokesperson for the Occupational Safety and Health Administration finally pointed me to the website of Deepwater Horizon Response, the U.S. government's "ongoing administration-wide response to the Deepwater BP Oil Spill." The link took me to a "fact sheets" page, where I was able to download Nalco's Material Safety Data Sheets for "Dispersant Type 1," Corexit 9500 (PDF); and "Dispersant Type 2," Corexit 9527A (PDF). These product numbers matched the ones that had been identified unofficially by my sources.
Bioconcentration game
OSHA requires companies to make Material Safety Data Sheets, or MSDSs, available for any hazardous substances used in a workplace, and the ones for these dispersants both contain versions of a disturbing statement. 9500's states that "Component substances have a potential to bioconcentrate," while the one for 9527A has the slightly more comforting, "Component substances have a low potential to bioconcentrate."
This is not what you want to hear about toxins being dumped in the sea by the hundreds of thousands of gallons. The EPA defines bioconcentration as the "accumulation of a chemical in tissues of a fish or other organism to levels greater than in the surrounding medium." In other words, substances that bioconcentrate tend to move from water into fish, where they can do damage to the fish itself, as well as be passed on to predator fish -- and on up the food chain, to human eaters.
And just how toxic is this stuff? The data sheets for both products contain this shocker: "No toxicity studies have been conducted on this product" -- meaning testing their safety for humans.
This is jaw-dropping. According to Ronald Tjeerdema, chair of the Department of Environmental Toxicology at UC Davis' College of Agricultural & Environmental Sciences, who has been studying dispersants since the '90s, "The industry typically only stockpiles one or two of these things," and while Corexit 9527 has been the dispersant of choice for a long time, in recent years, Corexit 9500 has gained prominence. Yet Nalco has done no toxicity studies on these industry-dominating products now in heavy use in the Gulf?
They do appear to have toxic properties. Both data sheets include the warning "human health hazards: acute." The MSDS for Corexit 9527A states that "excessive exposure may cause central nervous system effects, nausea, vomiting, anesthetic or narcotic effects," and "repeated or excessive exposure to butoxyethanol [an active ingredient] may cause injury to red blood cells (hemolysis), kidney or the liver."
It adds: "Prolonged and/or repeated exposure through inhalation or extensive skin contact with EGBE [butoxyethanol] may result in damage to the blood and kidneys."
Just the surfactants, please
So, what's in the stuff? According to their data sheets, both 9500 and 9527 are composed of three potentially hazardous substances. They share two in common, organic sulfonic acid salt and propylene glycol. In addition to those two, Corexit 9500 contains something called "Distillates, petroleum, hydrotreated light," while Corexit 9527 contains 2-Butoxyethanol. Frustratingly, the sheets don't give exact information about how much of the substances are in the dispersants; instead they give ranges as a percentage of weight. For example, Corexit 9500 can be composed of anywhere from 10 to 30 percent petroleum distillates, while 2-Butoxyethanol makes up anywhere from 30 to 60 percent of 9527.
