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?