Did Exxon know the primary ingredient in Corexit is very toxic?

A worker sprays dispersants into the ocean

Exxon researchers have already admitted that its dispersant products, Corexit 9527A and Corexit 9500A, are significantly toxic for aquatic life. But no one knew how toxic the chemicals are for humans. John Sheffield, president of Alabaster Corporation, which makes Sea Brat 4, a safer, less toxic alternative to Corexit, contacted me with accusations that he believes Exxon has known for quite a while that the primary ingredient in Corexit is very toxic.

He included the material safety data sheets for various Corexit products and documents issued from the companies involved to support his claims, which I have pasted below (pdf). In some cases, I have included screen shots from outside sources (CITGO, for example) to bolster Sheffield’s claims.

This gets a little dense, but the key word to look out for is”Norpar,” Exxon’s line of solvants.

Sheffield writes:

This product (Norpar) is basically kerosene. Although kerosene and napthalene (cigarette lighter fluid) are typically the main ingredients.