Richard Denison, Ph.D., is a Senior Scientist.
Just as BP seems to be making some progress in slowing the leakage of oil from Deepwater Horizon, another leak has appeared. Karen Dalton Beninato, writing on NewOrleans.com, has obtained, and posted for all to see, a copy of BP’s June 2009 “Gulf of Mexico Regional Oil Spill Response Plan” (caution, it’s a 600-page, 29 MB PDF file!). [Note added 6/8: Not sure how long it's been posted, but the BP Plan is up on the Minerals Management Service website, under "Documents" here (double caution: this version is a 61 MB PDF!)]
There are some embarrassing parts, with no doubt more waiting to be discovered. Here’s one example: The Plan’s “worst-case scenario” for sites more than 10 miles offshore is a total leakage of 177,400 barrels of crude oil (Appendix H). As reported by the Washington Post this morning, government estimates put the size of this spill at between 23 and 47 million gallons, or between 548,000 and 1.12 million barrels, and counting.
On the issue of dispersants, the Plan is also revealing.
First, it’s pretty clear BP has never given serious consideration to using any dispersants other than Corexit®. Of the 175,000 gallons of stockpiled dispersants listed in the Plan, all but about 1,000 gallons was Corexit®.
Second, BP was aware of the limited effectiveness of the Corexit® dispersants. The Plan provides (in Section 18, Dispersant Use Plan) the Corexit® data from EPA’s National Contingency Plan Product Schedule that I discussed in an earlier post – as well as data indicating even lower effectiveness on South Louisiana crude from an EPA Office of Research and Development report: a 45.4% effectiveness for, and an appalling 31% effectiveness for Corexit® 9527 – BP’s dispersant of first resort in the current spill.
Third, and perhaps most curious, while it faithfully reproduced EPA’s effectiveness data, not so with the acute aquatic toxicity data. In the same section of the Plan, BP provides unreferenced toxicity values for the two Corexit® dispersants from tests conducted on the same species of fish and shrimp that were used in the EPA tests. But all of BP’s values indicate much lower toxicity, up to an order of magnitude lower, compared to the official values listed in EPA’s National Contingency Plan Product Schedule. Here are the data (note that, with these toxicity values, the smaller the number, the higher is the toxicity):
|LC50* values in parts per million (ppm)|
|Menidia (inland silverside fish)|
|Corexit® 9500||EPA data||2.61||3.40|
|Corexit® 9527||EPA data||4.49||6.60|
|*LC50 = concentration at which 50% of the test organisms are killed within the duration of the test.|
Wonder where BP got its data and how and why it decided to cite those instead of EPA’s? [Note added on 6/7: One possible explanation for the difference is that EPA's standard tests are done on a 1:10 mixture of dispersant and oil. A number of reports (e.g., see here) indicate that in many cases the mixture is more toxic than the dispersant alone. But why wouldn't BP report data that followed EPA's official method for testing dispersants in the National Contingency Plan?]
[One note: The original article by Karen Dalton Beninato on NewOrleans.com made an understandable mistake in stating that the Plan indicates no ecotoxicity testing has been done on Corexit®. In fact, Section 18 of the Plan does include such data, limited as they are. One of the material safety data sheets (MSDS) from the dispersant maker, Nalco, that is reproduced in the Plan, does include such a statement. However, the MSDSs in the Plan are old (2004 and 2005), and more recent MSDSs, available here, do contain some ecotoxicity data, some of which matches the data I've cited in the table above.]
Speaking of toxicity: BP’s Plan includes the material safety data sheets (MSDS) from Nalco, the maker of the Corexit® dispersants. In each MSDS, under the section for “toxicological information,” where any available human health-related test data would appear, the following statement appears: “No toxicity studies have been conducted on this product.” So much for any concern about the workers dispersing the dispersants, the workers and volunteers involved in the clean-up, and the local residents who will have to live with this mess for years or decades to come.
Finally, there are a couple of interesting entries on Section 18’s “dispersant decision checklist”:
Under the first question – “Is the spill/oil dispersible?” – a note reads:
“Some modern dispersants may be formulated to be effective on a wider range of oil properties. The choices of dispersants listed on the NCP’s National Product Schedule are limited. To answer this question, you should look at which dispersant would the most effective given the type of oil (emphasis added).”
Apparently someone forgot to check the Product Schedule: As I noted in my earlier post, among the 18 dispersants rated by EPA, the two Corexit® dispersants rank 13th and 16th in effectiveness on South Louisiana crude.
The second question on the checklist is: “Have environmental tradeoffs of dispersant use indicated that use should be considered?”
Alongside the simple Yes/No checkboxes provided for answering this question, a helpful hint is offered: “Note: This is one of the more difficult questions.”
But overall, this looks to me like another classic case of a leak leading us all to have to ask: What did they know, and when did they know it?