1 fossil water and has a composition different from that of sea water, 



2 even though usually it is a saline brine, it has elevated levels of 



3 several metals, and according to current permits, a certain 



4 concentration of hydrocarbons are allowed in produced-water discharge. 



5 Then, of course, you always have the danger of an accident from a 



6 blowout or an operational spill. So, these are types of potential 



7 problems that could be encountered during offshore exploration and 



8 production. 



9 The major concern is related to the drilling fluids, because that 



10 is a so-called manmade product that is discharged intentionally during 



11 drilling. Because of that concern, there have been a large number of 



12 bioassays performed to determine the toxicity of drilling fluids from 



13 different offshore sources 



14 This is an old slide, I am sure there have been several thousand 



15 additional drilling-mud bioassays because it is part of all current Gulf 



16 of Mexico permits, and I believe West coast permits, too, that you do a 



17 bioassay periodically during drilling. 



18 Anyway, I think the results would be very similar, even if we 



19 updated this with all the latest data. Basically when I did this there 



20 had been at least 400 bioassays done with all kinds of offshore drilling 



21 muds. 



22 Of these, 79 percent or 41, actually these are cumulative, but 79 



23 percent of the assays gave results in the greater than 10,000 ppm range, 



24 which means practically non-toxic. By the time you get down to just 



25 under 10,000 ppm, or the LC-50 value, 91 percent of the assays were 



26 slightly toxic to practically non-toxic. 



27 In looking at the composition of these muds it became clear that 



28 the more toxic muds were those that contained elevated levels of 



29 hexavalent chromium salts or diesel fuels, which is added quite 



30 frequently, or at least in the past, to drilling fluids for various 



31 purposes. 



32 So, the industry and EPA jointly developed a generic drilling-mud 



33 program where basically the composition of the muds were characterized 



89 



