Posted by: tomemerald | 05/6/10 | 12:06 pm | to wired.com
The supposedly proprietary composition of the dispersant Corexit 9500 is a joke being played on journalists. Its chemical composition was disclosed years ago in toxicity studies and patent and regulatory filings, all in the public domain and all readily available on the internet.
First note Corexit 9500 does not contain 2-butoxyl ethanol, unlike its predecessor Corexit 9527 (which caused adverse health effects in Exxon Valdez responders). The solvent was replaced in Corexit 9500 by propylene glycol and a mixture of food-grade(!) aliphatic hydrocarbons called Norpar 13 (n-alkanes ranging from nonane to hexadecane according to ExxonMobil rsearchers Varadaraj et al. in 1995).
Second, the supposedly secret sulfonic acid salt was disclosed in the 2001 patent filing US 6168702. The basic chemicaly formula is that of a sulfonic and carboxylic double quaternary amine salt but a range of substituents makes the overall composition quite variable. The patent filing shows a picture of the chemical which conveys its chemical makeup.
Third, Corexit 9500 contains two non-ionic surfactants, Tween 80 (eicosethoxy sorbitan monooleate) and the somewhat similar Span 80 (ethoxylated sorbitan mono- and trioleates).
Relatively little toxity testing has been done with either version of Corexit. Oil is only dispersed from the surface into the greater volume of undersea water and neither goes away in the short term. Better or worse, nobody can really say for sure.
************************************************Propylene glycol is an ingredient in food colouring and liquid vanilla flavoring. It is also used in inkjet printer ink. Anyone for vanilla cupcakes with thick green icing? Yum yum.