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  •  How many ppm are considered toxic? (1+ / 0-)
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    And, how many might one oyster or shrimp ingest in its lifetime.

    If you eat that shellfish, you eat the Corexit it ingested.

    How many oysters or shrimp do you eat at a sitting?

    •  I am not eating much seafood.... (2+ / 0-)
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      OrdinaryIowan, David Kroning II

      I am not very wealthy.  

      I am fine with the entire fishery shutting down for the future until the products are shown to be safe.  I think that would help restore the fishery which is compromised by the oil spill- and fishing now will put too much pressure on the ability of the system to restore itself.  And I really doubt if bioaccumulation of detergents is a bigger problem that a bird diving into a foot of oil with a sheen of water over it.  And that is what is killing the birds and vulnerable sea mammals.  I bet the shrimp make it better than the pelicans.

      You shall know the truth, and the truth shall make you mad. Aldous Huxley

      by murrayewv on Tue Jun 15, 2010 at 06:44:32 AM PDT

      [ Parent ]

      •  Since you'd didn't answer the question (0+ / 0-)

        Here's the answer:

        "Corexit is is four times more toxic than oil (oil is toxic at 11 ppm (parts per million), Corexit 9500 at only 2.61ppm)," said Yobie Benjamin, who writes a blog on the website of the San Francisco Chronicle. See,

        And surprise, surprise, its considered carcinogenic:

        The independent watchdog group OMBWatch cites the New Jersey Department of Health to point out possible dangers of one of the the ingredients.  The document indicates 2-butoxy-ethanol:  "may be absorbed through the skin; should be handled as a CARCINOGEN -- WITH EXTREME CAUTION; can irritate the skin and eyes with possible eye damage; can irritate the nose and throat; can cause nausea, vomiting, diarrhea and abdominal pain. can cause headache, dizziness, lightheadedness, and passing out and may damage the liver and kidneys."

        And, here's a more detailed breakdown of the ingredients:

        Environmental Protection Agency
        June 2010

        What are the chemical components of the dispersants COREXIT 9500 and COREXIT 9527?

        The components of COREXIT 9500 and 9527 are:

        CAS Registry Number              Chemical Name
        57-55-6                                   1,2-Propanediol
        111-76-2                                 Ethanol, 2-butoxy-*
        577-11-7                                 Butanedioic acid, 2-sulfo-, 1,4-bis(2-ethylhexyl) ester, sodium salt (1:1)
        1338-43-8                               Sorbitan, mono-(9Z)-9-octadecenoate
        9005-65-6                               Sorbitan, mono-(9Z)-9-octadecenoate, poly(oxy-1,2-ethanediyl) derivs.
        9005-70-3                               Sorbitan, tri-(9Z)-9-octadecenoate, poly(oxy-1,2-ethanediyl) derivs
        29911-28-2                             2-Propanol, 1-(2-butoxy-1-methylethoxy)-
        64742-47-8                             Distillates (petroleum), hydrotreated light

        *Note: This chemical component (Ethanol, 2-butoxy-) is not included in the composition of Corexit 9500.

        Learn more about CAS Registry Numbers from the American Chemical Society

        •  thanks ...... (0+ / 0-)

          a computer guy who is a business consultant is telling you this.

          I am sure he is sincere.  But excuse me if I remain unconvinced by his data.  You are citing a blogger who isn't citing their references.  I think after looking hard, he is reading the data submitted by manufacturer to the EPA  Oil vs Corexit "toxicity" isn't informative?  The same data is cited by the Environmental Defense Fund.

          The problem is that it is more toxic in a 20 liter sealed bottle where the oil still remains- but the oil breaks up into the water column and causes less damage to the shore.  They sacrifice the microorganisms and invertebrates for the sake of the shore.

          The question of Corexit 9500 can be answered with

          Here is what EPA says it is for Corexit 9500....

          Menidia  (96-hr)  (A silverside fish)  2.61 ppm

          Mysidopsis  (48-hr) ( an invertebrate)  3.40 ppm

          Please observe that in this long list of dispersants, Corexit is one of the least toxic.  A couple are less toxic to the invertebrates but Corexit 9500 is the least toxic to the fish.

          This paper indicates that these are very conservative tests, and actual toxicity is probably less.  The tests have limitations when done in closed carboys (like a big sealed 20 liter bottle) since all the oil is still present as evaporant.  So a very conservative test is going to overestimate actual toxicity, which hopefully makes this less harmful once much diluted after spraying.  

          For a lot more toxicology information, check out this reference

          this lists the species, hours exposure (different in various species) and the next page, the ppm for an LD50 (lethal dose 50- the dose where 50% of the organisms die).  

          Oil spill dispersants do not actually reduce the total amount of oil entering the environment. Rather, they change the inherent chemical and physical properties of oil, thereby changing the oil’s transport, fate, and potential effects. Small amounts of spilled oil naturally disperse into the water column, through the action of waves and other environmental processes.

          The objective of dispersant use is to enhance the amount of oil that physically mixes into the water column, reducing the potential that a surface slick will contaminate shoreline habitats or come into contact with birds, marine mammals, or other organisms that exist on the water surface or shoreline. Conversely, by promoting dispersion of oil into the water column, dispersants increase the potential exposure of water-column and benthic biota to spilled oil.

          Dispersant application thus represents a conscious decision to increase the hydrocarbon load (resulting from a spill) on one component of the ecosystem (e.g., the water column) while reducing the load on another (e.g., coastal wetland). Decisions to use dispersants, therefore, involve trade-offs between decreasing the risk to water surface and shoreline habitats while increasing the potential risk to organisms in the water column and on the seafloor. This trade-off reflects the complex interplay of many variables, including the type of oil spilled, the volume of the spill, sea state and weather, water depth, degree of turbulence (thus mixing and dilution of the oil), and relative abundance and life stages of resident organisms.

          So the LD50 (if that is indeed the comparison being proffered by your blogger) for some unnamed organism is not shocking.  The dispersants cost the easily regenerated part of the ecosystem and save the otters and dolphins and pellicans and the mangroves.  It isn't fair, but it is a lot easier to repopulate the microorganisms and shrimp than it is the coastal ecosystem.

          It is a no win choice, but it is a lose less choice.  We lose less of the harder to restore environment.  

          Sorry, that is all I have.  You can save more invertebrates or more mangroves.  I pick mangroves.

          Sorry to go all technical on you, but this sort of "cite a computer blogger with an out of context factoid with no citation to original literature" oversimplifies this real scientific issue.

          I guess I think Obama is smarter to listen to real experts who try to put the data in an ecological context rather than make a false oversimplified case for abandoning dispersants.

          I wouldn't advise breathing a lot of this Corex9500 stuff- but they are spraying from the air off shore on the oil, not the shores.  That is recommended- you want to disperse the oil into the water.


          You shall know the truth, and the truth shall make you mad. Aldous Huxley

          by murrayewv on Tue Jun 15, 2010 at 06:55:56 PM PDT

          [ Parent ]

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