Thom has been right on message with his "Out of Sight - Out of Mind" argument against the use of dispersants in the Gulf of Mexico.
Years ago I attended an inter-agency meeting at the Dept of Ecology in Washington State. Even though I have cited numerous studies devoloped by NOAA scientists in response to the Exxon Valdes oil spill, unfortunately I found myself opposing several of these scientists because they were approving the use of dispersants.
In their defense, these NOAA scientists approved of the use of dispersants primarily because the oil had such a devastating impact on nearshore resources (even today, 50% of test pits dug in the nearshore areas affected by the Exxon Valdes oil spill show oil still remains on spill affected beaches). Arguably, nearshore resources and ecosystems are by far the most biologically active and includes the more complex sensitive habitats as compared to other habitats. The argument for using dispersants were to avoid the fragile nearshore environment; given the experience of the NOAA scientists I understand but continue to disagree, it allows for far too much "Out of Sight - Out of Mind" slight of hand.
As an Environmental Specialist and observer of several spill events in Washington State, I opposed the use of dispersants for the same reason Thom Hartmann suggested on his show today, I was particularly concerned when I realized that the dispersants (at that time) appeared to be more toxic than the oil (and it was being proposed using very questionable science). At the time, Wash Dept of Ecology.told us they intended to include dispersants as a one of several methods for responding to oil spills; I'm sure this was in response to directions from the Bush Administration's EPA.
If we are going to continue to be forced to accept policies that have potential to exacerbate a disaster of global proportions, we have no choice but try to defend our environment using what tools we have.
Hopefully we can use this disaster as an opportunity to evaluate the actual toxological effects resulting from the use of dispersants WITHOUT the influence of the oil industry. Perhaps the next generation of NOAA scientists will be able to come up with an additional multiplier to be applied after determining natural resource damages, and added to the total.
In addition, determining natural resource damages is also a concern. Due to dispersant use, much of the resource damage will be underestimated because it won't be seen on the beaches or water's surface. Much of the assessment should require visual observations by submarine and remote operated vehicles (ROV) from now until we are certain they have fully characterized the damages. We also need to accept that without a miracle, much of the damage from the Gulf spill event will be permanent.