“Even Prof Overton has emphasized we can’t see right now what is going on under the surface of the water and won’t know for several years the extent of the damage or the long-term effects of the use of this much dispersant over such a large area for such a long period of time.”
I very seriously doubt that Ed said anything remotely like that. As I recall, he said that no studies of such releases have been done and the effects are unknown. But we “do” know that there will be ZERO “long-term-effects” from the dispersants, because they just don’t hang around that long. What is it about “unstable in aqueous solution” that you don’t understand?? Most of the dispersants put out have long since disappeared from the environment due to their natural degradation
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He is definitely a cheerleader for dispersant use as the lesser of two evils that kept the oil from beaches and marshes, but I haven’t seen a quote anywhere predicting positively zero long-term effects. Obviously adopting such an absolutist posture would seriously weaken the credibility of any expert testimony, which is why scientists normally hedge their statements in much more moderate terms.
“We don’t know whether it’s (dispersant use) affecting wildlife or not,” said Ed Overton of Louisiana State University in Baton Rouge. “We’re right in the middle of this. We really won’t know for a while yet.”
OVERTON: We don’t know still, but the early evidence certainly doesn’t indicate that it’s (the spill) going to have traumatic, draconian, long- term damaging effects. So, I think that’s probably a stronger statement than I personally would have used. But I don’t want to underestimate the severity of the damage. I mean, most of the damage, remember, is not what we can see. We saw the dead pelicans and the dolphin and the other sea life and the birds, but there was a lot of damage that nobody ever saw, and we won’t know how severe that was for several years to come.
Well, I don’t know. I didn’t certainly overblow it. People that have been around an oil spill for a long time I don’t think overblow it. There was plenty of damage, is plenty of damage. We won’t know the total carnage for several years. This is part of the natural resources damage assessment effort. Also, there’ll be independent scientifically based programs that will try to understand and completely catalog the damage.
So, there was plenty of damage done. I don’t think we should underestimate that. It’s just that some people over speculated, let me put it like that, that the Gulf would die, things like this. And that’s just not in line with what normally occurs in an oil spill.
http://www.cnnstudentnews.cnn.com/TRANSCRIPTS/1007/29/acd.01.html
Why was this dispersant discontinued if it wasn’t showing negative effects ?
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In order for species that BREATH AIR to be affected, the dispersants have to be AEROSOLIZED (made into very small droplets suspended in the air). Because the ingredients of the dispersants are highly polar molecules (except for the kerosene), they do NOT aerosolize easily. And in order to lodge in the lungs, the aerosol particles have to be in a VERY narrow size range. Too big and the natural filtration in the nasal passages removes them and expels them with the mucus. Too small and they don't "stick" in the lungs surface.
The individual compounds that make up the dispersants that "do" get into the body are destroyed by the body's natural defenses. For example, propylene glycol, one of the major ingredients in Corexit 9500, is removed from the body with a half-life of nine hours.
The reason there will be ZERO long-term effects is because after some reasonably short time, the dispersants are GONE, and not available to cause toxic effects.
Now, when I say ZERO long term effects, I am talking about to humans (and higher species). The dispersants are definitely going to kill some fish. But fish recover very quickly. "Unoccupied" ecological areas are rapidly recolonized from non-exposed areas.
You are being misled by the favorite tactic of the greens. They dig up an MSDS sheet and post it as "proof" that "we're all gonna die". What they don't tell you is that the symptoms of exposure listed are due to both acute exposure and to chronic exposure. But in the real world, the types of effects seen are strictly determined by the dose, with certain symptoms associated with short-term acute exposures, and others to long-term chronic exposures.
I'm not aware of ANY human being that has had a sufficiently high exposure from the spill to result in acute poisoning symptoms. All the data that I have seen puts the possible dosages well below the threshold of acute toxicity effects.
And both the EPA and OSHA scientists who have commented on the data say exactly the same thing.