Chemical Dispersants and Crude Oil - Efficacy and Toxicity

This is a guest post by Dr. Stephen R. Humphrey, known on The Oil Drum as NatResDr. Steve Humphrey has been on the faculty of the University of Florida since 1971. Currently he is Director of The School of Natural Resources and Environment. He also was a member of the Florida Environmental Regulation Commission for 8 years.

One of the striking controversies about the massive BP Deepwater Horizon oil well blowout has been alarm raised about chemical dispersants used to hold spilled crude oil deep in the Gulf of Mexico. Prospects for oil’s direct harm to the environment, the economy, and coastal society were immediately obvious. But why were people so concerned that dispersing the oil was bad—worse than allowing it to come onshore? Is this just a case of “out of sight, out of mind” to benefit the oil company, or are there larger benefits that reduce the harms to other interests?

Initial accounts were vague, so I decided to don my rubber Spock ears and survey the scientific literature—more information signal, less noise. What do we really know about the use of dispersants? What do they do? What benefits and problems do they bring? I was most interested in the efficacy of dispersants. I read scores of peer-reviewed scientific articles, and below I highlight a few of the most informative studies, providing enough detail that the technically-minded reader should be able to judge the content. I also provide notes on other important questions, such as whether dispersants are toxic on their own and whether they make crude oil more or less toxic than it otherwise would be. Further review of such questions is warranted, however.


As background, here are two of the better press reports on using dispersants on the BP oil spill:

Researchers Worry About Oil Dispersants’ Impacts, Too

Slick Solution: How Microbes Will Clean Up the Deepwater Horizon Oil Spill

Use of dispersants on the BP spill reportedly began on April 27, 2010, but Corexit 9527A use was soon discontinued in favor of Corexit 9500.

Substantial information about dispersant use on this oil spill is provided at the EPA website.

Simply put, the purpose of dispersant is to emulsify the oil, like bacon grease in soapy dishwater. In the case of oil released underwater, dispersant reduces the amount of oil surfacing, hence reducing danger and toxicity for the topside workers trying to repair the damaged well and contain the spill. It also increases surface area and time for oil-droplet exposure to microorganisms in the water column. The microbes digest the oil into simpler and much less harmful chemicals, much as happens with household sewage in a septic tank or wastewater treatment plant.

Efficacy of dispersants

Much is known about which organisms (the biotic components) are important hydrocarbon degraders in the environment, the metabolic degradation pathways (the process mechanisms), and the fate of hydrocarbons in the environment, both in the presence of oxygen and its absence, as recently reviewed by Head et al. (2009; citation below). More than 200 genera of bacteria, cyanobacteria, fungi, and algae are known to degrade or transform hydrocarbons, using them for energy and carbon. Oil-consuming bacteria include sulfate-reducers and acid-producers, which thrive in anaerobic waters, whereas general aerobic bacteria require oxygen. Thus dissolved oxygen is not necessarily limiting to marine oil degradation (but low sulfate availability could be limiting in some situations). More generally, oil degradation in marine waters is strictly limited by the availability of nitrogen and phosphorus, and it also may be limited by bioavailability of the oil, as in cases of burial by mud or beach sand. Oil degradation is also temperature-dependent, but like surface waters, extreme marine environments (such as deep, dark, cold, high-pressure waters) also are occupied by diverse locally-adapted micro-organisms, including oil degraders (Margesin and Schinner. 2001. Biodegradation and bioremediation of hydrocarbons in extreme environments. Applied Microbiology and Biotechnology 56:650-663).

Crude oil is complex stuff, with four operationally defined groups of chemicals: saturated hydrocarbons, aromatic hydrocarbons, resins, and asphaltenes. Light crude is typically higher in the first two (lighter) groups than the last two heavy (polar) ones. At the marine surface, physical reduction (via evaporation and photo-oxidation) and biodegradation of light crude greatly reduces the proportion of the lighter fractions and increases the proportion of the heavier fractions. In deeper, dark waters, biodegradation proceeds without the benefit of the physical processes. In either place, degradation of the most voluminous fraction (saturated hydrocarbons) is prominent in reducing the volume of a spill, but the aromatic and heavy fractions are more toxic and persistent, so their fate is also quite important.

Head, Jones, and Röling. 2006. Marine microorganisms make a meal of oil. Nature Reviews Microbiology 4:173-182.

Normally the hydrocarbon-degrading organisms are diverse and widespread but not common in the environment. When crude oil is introduced, however, these organisms are favored by the new conditions, and their populations bloom and become very abundant in a short time. Some of these organisms consume mainly saturated hydrocarbons, while others consume mainly aromatic hydrocarbons, and these fractions can be largely removed within a few weeks by biodegradation.

Lessons learned about biodegradation and remediation of oil spills have come mainly from beach sites and laboratory microcosm studies; much less is known about the course of open-ocean spills, whether treated or not. Both beach and ocean surfaces can be treated with dispersants and or fertilizers, but deepwater environments can be treated only if injection at the oil source is an option. Note that such deepwater injection, if overdone, would cause undesirable pollution in its own right. In microcosms, Röling et al. (2002) showed that the amount of oil degradation is strongly related to the amount of nitrogen and phosphorus available. With no fertilizer added, oil degraded quite slowly, but small amounts of nutrients were introduced by death of the microbial biomass, suggesting that a self-reinforcing process operates, albeit modestly. Oil degradation in fertilized microcosms proceeded more rapidly when more nutrients were provided, but the final extent was similar if enough time passed. Managed addition of particular oil-degrading organisms has often failed to improve biodegradation, either because factors other than the presence of particular organisms is important or because the organisms added are poorly adapted to the field environment and thus have poor survival.

Röling, et al. 2002. Robust hydrocarbon degradation and dynamics of bacterial communities during nutrient-enhanced oil spill bioremediation. Applied Environmental Microbiology 68:5537-5548.

Venosa and Holder (2007) measured biodegradation of the highly bio-available fractions of dispersed crude oil, using Corexit 9500 and JD2000 in laboratory flasks that were constantly shaken. The rate of degradation was strongly temperature-dependent because of lower bacterial metabolic rates at lower temperatures. Degradation was much more rapid for dispersed oil than for non-dispersed oil, because in the non-dispersed control the microbial culture first had to generate its own biosurfactant to emulsify the oil before substantial degradation could occur. Eventually, however, the degradation of non-dispersed oil caught up with that of dispersed oil in terms of residual concentrations.

Venosa and Holder. 2007. Biodegradability of dispersed crude oil at two different temperatures. Marine Pollution Bulletin 54:545-553.

Zahed et al. (2010) studied biodegradation of light crude oil (the full complement of fractions) in seawater samples taken into the lab from coastal Malaysia (several sites to obtain representative biotic communities), using Corexit 9500 dispersant. They measured removal of total petroleum hydrocarbons over 45 days under several treatments, with initial oil concentrations of 100, 500, 1,000 and 2,000 mg/L. Treatments were

(1) seawater with locally acclimated microorganisms cultured in fertilizer (CO),
(2) seawater with microbes cultured in fertilizer plus Corexit 9500 dispersant (DCO),
(3) natural attenuation of oil in seawater with no culture, fertilizer, or dispersant, and
(4) abiotic control seawater, treated with biocide to show effects of purely physical reactions.

(There was no treatment that included dispersant without cultured organisms and fertilizer.) Abiotic oil loss (evaporation, photo-oxidation and other physical reactions in the absence of microbial activity) in this study was 20%. Natural attenuation resulted in 25-32% oil removal, with more removal occurring the lower the initial concentration. DCO oil loss ranged from 45 to 67%, again with more removal occurring the lower the initial concentration. CO oil loss ranged from 38 to 64%. Thus one-third to two-thirds of the oil was destroyed via biodegradation over the course of 6 weeks. The oil-loss timelines show that long exposure of the oil to biodegradation processes was needed to maximize benefits of the breakdown process.

Zahed et al. 2010. Effect of initial oil concentration and dispersant on crude oil biodegradation in contaminated seawater. Bulletin of Environmental Contamination and Toxicology 84:438-442.

Toxicity of dispersants

The US National Research Council issued a report on dispersants in 2005. The report succinctly noted the tradeoffs involved in dispersant use: “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.”

The report identified several critical knowledge gaps, including toxicity to particular organisms from exposure to dispersed oil, the final fate of chemically dispersed oil, and the effectiveness of dispersants for different oil types and environmental conditions. One key finding was: “The mechanisms of both acute and sublethal toxicity from exposure to dispersed oil are not sufficiently understood. Recent studies in the literature suggest that toxicity from physically and chemically dispersed oil appears to be primarily associated with the additive effects of various dissolved-phase polynuclear aromatic hydrocarbons (PAH) with additional contributions from heterocyclic (N, S, and O) containing polycyclic aromatic compounds. Additional toxicity may be coming from the particulate, or oil droplet, phase, but a particular concern stems from potential synergistic effects of exposure to dissolved components in combination with chemically dispersed oil droplets.”

Based on that finding, the NRC report recommended that “Relevant state and federal agencies, industry, and appropriate international partners should develop and fund a series of focused toxicity studies to determine the mechanisms of both acute and sublethal toxicity to key organisms from exposure to dispersed oil.”

However, relatively little subsequent progress has been made on the research agenda identified in the NRC report. A major reason that the body of research on dispersants is inconclusive (inconsistent among studies) is that disparate methodologies have been used.

In June 2010, the EPA reported toxicity tests of 8 dispersants (not combined with crude oil), including those being used in the BP spill. The dispersants were roughly similar to one another in toxicity when tested on the EPA-standard test organisms, mysid shrimp and silversides fish. The dispersants were also generally less toxic than oil, and they were expected to biodegrade in weeks or months rather than years as is the case for oil.

Fuller et al. (2004) applied standard EPA test protocols to mysid shrimp and silversides and sheepshead fish exposed to Arabian crude oil, Corexit 9500 dispersant, and oil plus dispersant. Oil plus dispersant was equal or less toxic than oil only. Continuous exposures were generally more toxic than declining exposures. Unweathered oil-only (dominated by soluble hydrocarbon fractions) were more toxic to silversides than weathered oil-only in which colloidal oil fractions dominated. Oil-plus dispersant media prepared with unweathered and weathered oil showed no difference in toxicity. The authors inferred that toxicity was a function of the soluble crude oil components and not the colloidal components.

Fuller et al. 2004. Comparative toxicity of oil, dispersant, and oil plus dispersant to several marine species. Environmental Toxicology and Chemistry 23:2941-2949.

Now the US EPA is testing the toxicity of Louisiana sweet crude oil combined with dispersant. These important results are expected by the end of July 2010.

A recent study indicates that dispersants alone are directly toxic to corals (Shafir, Rijn, and Rinkevich. 2007. Short and long term toxicity of crude oil and oil dispersants to two representative coral species. Environmental Science & Technology 41:5571-5574; Corexit was not tested in this study). Several coral reefs are in the vicinity of the BP oil slick, including the Flower Bank Gardens off the coast of Louisiana and Texas (designated as a marine sanctuary in 1992) and the Florida Middle Grounds, off the Florida panhandle. This issue may also be relevant to the Florida Keys, Yucatan, and Cuba.

Another issue worth watching is potential health problems for workers handling dispersant:

New BP Data Show 20% of Gulf Spill Responders Exposed to Chemical That Sickened Valdez Workers

New Data from BP’s Coverup Firm Shows Dispersants in 20% of Offshore Workers

Final comments

Prolonging spilled crude oil's exposure to offshore sea life increases environmental harms in ways we don't understand very well, and these harms are probably much worse than we know. In my opinion there's no silver lining among the tradeoffs, only trading off one bad against other bads.

It’s remarkable to me how much people have discussed toxicity of dispersants, and how little people have discussed the toxicity of crude oil, which is high for people and many other organisms. We definitely need to learn whether dispersant allows the oil to degrade fast enough and in large enough quantities to offset damage done by spreading the oil through more of the environment for longer. But we also need a comparable public discussion of the toxicity of the oil to people, to habitats and animals along the shore, and to the myriad creatures of the Gulf of Mexico.

Has there been any consideration of injecting nitrogen, phosphorous and sulfate, in addition to the dispersant, into the oil stream? The quantities that would likely be helpful would probably be a tiny fraction of what is already entering the Gulf via the Mississippi, so they might not add significantly to the existing fertilizer burden.

Then you may want to add oxygen as well. I'd love to see the stochiometric calculations showing how much oxygen is consumed by bacteria digesting the oil. To tell you the truth, I studied physical oceanography 41 years ago, and I'll be darned if I didn't toss out the textbook last year. So I don't have the reference for oxygen concentration in seawater. But I would worry about the oxygen going way low if they were to try to make the oil spill area into a restaurant for bacteria.

Nitrate also can work for facultative bacteria instead of oxygen. They would need to be injecting an awful lot of oxygen or air or nitrate to equal the biochemical oxygen demand of the oil. More likely, they will just have to depend on the oxygen already dissolved in the water, which could cause problems with aquatic life if the oxygen depletes too fast.

fdoleza -

Intense microbial activity depleting the dissolved oxygen is certainly a legitimate concern.

As it is (and possibly surprising to some), oxygen is not all that soluble in water. In the range of water temperatures typically encountered in the Gulf, the saturation concentration for oxygen is only on the order of about 10 parts per million (weight basis). That is not a whole hell of a lot, so is is easy to see how even a modest amount of accelerated aerobic microbial activity can completely deplete oxygen levels on a localized basis.

Fortunately, the Gulf is not a small stagnant enclosed pond, so given the amount of mixing, low-oyxgen zones show be confined to more or less localized hot spots. At least fish have the ability to avoid low oxygen zones and seek areas with good oxygen levels. However, bottom organisms don't have quite the same ability to move on to greener pastures.

Oxygen depletion can be a real problem when doing bio-remediation, so one must proceed carefully and not get carried away in trying to accomplish too much too soon.

fdoleza -
Let me respond to your query about the oxygen required for HC catabolism by pasting from an earlier TOD comment
( ):

How do new plume estimates compare with Oxygen availability?

NOAA has just acknowledged that the extensive plumes of oil earlier reported are derived from the DWH spill ( ). Perhaps alarmingly they have adjusted upward the earlier cited concentration from .5 ppm to 1-2 ppm. In view of earlier reports of oxygen depletion (down to 30% normal), I wondered whether sea-water oxygen levels are sufficient to support full microbial oxidation of these higher levels.

Consider then the stoichiometry:
CH2 (hydrocarbon) with a gm-atomic wt of 14 requires
3 O atoms with a total gm-atomic weight of 48 for oxidation to CO2 and H2O
a weight ratio of 3.5

That means we require at least 7 ppm of oxygen in the seawater ( 3.5 x 2 ).

I take some comfort that the oxygen solubility in seawater at 10C is 35 ppm
( )

When challenged to demonstrate that the O2 levels at depth do in fact achieve their theoretical level, I responded further:

"What is the real O2 level at the depth of the plume?"
Samantha Joye of the UGA Dept. Marine Sciences, who originally reported 30% depletion in the plume, provides a graph of O2 vs depth in the region of the plume:

On the relative O2 recording, just above and below the plume at 1200 M depth, they show 80-90% of the levels at the surface. Relative to surface levels, O2 concentrations decline to 50% at 500 M depth, but then increase at benthic depths. I would assume that in the plume stratum .. some 500 M above the sea floor .. the origin of O2 is geological (i.e. acquired eons ago) rather than biological.

Dr. Joye's blog, with some answers to questions on the composition of the plume is here:
Regarding toxicity of the dispersant (or more correctly, the dispersant vehicle) I was unaware that Corexit 9500 (kerosene based) is now used exclusively. This does much to dispel the hysteria over the acute toxicity (e.g. hemolysis and tumors in rats) of Corexit 9527 that has been based on unqualified reference to toxicity tables for its vehicle, 2-butoxyethanol. (Personally, I'd prefer it to kerosene.)

Fred: Thanks for this, especially for the NOAA press release on the oil plume survey, which I hadn't seen. I've downloaded the full report and will take a look.

Readers should be aware that oxygen depletion in the Gulf has been going on for a long time, especially in the area influenced by the outflow of the Mississippi River. Wikipedia has an entry. It's not all due to those oil munching microbes.

Thanks. I guess my take is we shouldn't be adding a lot of chemicals to the soup until we know how the oxygen levels will be impacted. I'd hate to be a fish trying to swim around gasping for water.

Bio: Good question. This makes sense, but I haven't seen anything that speaks to it. Does anyone have anything? It's possible there's added fertilizer and we just haven't heard about it, but it's best to assume not unless we hear otherwise. Also, I haven't seen anything on breakdown products of Corexit.

Does not the influx of water from the Mississippi River to the Gulf provide sufficient N And P to degrade the oil?

Thank you Gail. Excellent article.

Dr. Humphreys last two paragraphs says it all.

Personally I have been disappointed by the tendency of the general public and most commenters to assume that dispersants are adding to rather than solving the oil pullution problem;but given the tendency of the govt and of BP to be less than fully forthcoming with the facts it is easy to see why most people would be ready to jump to such a conclusion.

My seat of the pants guess is that if the dispersants work well enough to prevent the creation of large new dead zones -which so far as I know have not been so far documented-the benefits will outwiegh the costs, but in such a case as this, there is no objective standard for comparision.

Who can say with any degree of certainty how much the damages that would have been caused by the oil coming ashore are "worth" in dollar or ecological terms compared to the "worth" of damages to the gulf in general caused by the dispersants?

A good many people who seem to have serious expertise in such matters seem to think that if the oil and dispersants do indeed degrade and disperse within a short enough time and over a large enough area, the damages to the greater gulf will be serious but mostly relatively short term.Otoh, a thoroughly oil saturated marshlands might not recover for decades, causing even more long term damages due to the loss of key habitat such as nursery areas for shrimp and fish.

The economic situation of the local coastal people seem to be heavily tilted towards using the dispersants, as tourism is such a big part of the economy;protecting that industry is of paramount importance.

Allowing the beaches to become badly contaminated could ruin the industry for years,and the cost of looking after the local people might be so large as to leave little or nothing for remedial measures.

There is always a bigger box or envelope to be considered.

Thanks for the compilation, NRD. I see that UF has organized a panel of scientists to start studying all of this. The studies available on the topic focus of efficacy of dispersal, which is the goal of oil companies, without any concern for toxicity. If I had the time I would want to pull up each study to see how the studies were funded. Dispersing the oil has the following effects: dispersal throughout the water column thus affecting broader levels of ecosystem, sequestering the mix in colder deeper water where it is not available to wind/wave action, thus probably prolonging the problem, mixing prevents efficacy of booms and skimming and burning, creates micelles of oil and dispersant which may markedly increase health hazards/toxicity to all, and the potential long-term issue of intrusion into ground water if the mix stays on the bottom. Not to mention aerosolization of dispersant if sprayed by air (they've stopped doing that?).

The real issue is toxicity, not efficacy of dispersal. There are less studies on this, and most do not address the time and dosage happening in this case. Many of the studies use 6 hour contact time with rinsing, to simulate tides. That's not the case here. Many of the studies apply the dispersant for short periods of time, less than 2 weeks. That's not the case here. Concentrations in most studies are much less than the case here. Funding of the toxicity studies is probably also suspect? I would simply throw out any that are funded by the dispersant companies in any way, shape, or form. Many of the studies compare one type of dispersant to the other, without comparing to placebo or natural attenuation. This is the same classic trick that drug companies use. Claiming that one method is better than the other without examining long term attenuation with artificial intervention is the real question, and I doubt any studies have looked at that long term, in combination of both oil and dispersant? Anyone got a good link?

I'm glad that OFM is so comforted, although he uses seems and appears a lot. I am not comforted by this at all.

I am not altogether comforted, and the "seems" used frequently are indeed there to indicate that I am doubtful as to what the true facts are.

I am simply withholding final judgement and acknowledging that my current opinion is only a guess, no more and no less.

But the case for dispersants seems very strong to me-IF the oil is truly dispersed far and wide, to the extent that there are no extensive new dead zones created.

It is a basic principle of toxicology that the dose makes the poison;a little oil in a lot of water may reasonably be expected to cause less harm than a lot of oil in a small amount of water.

A modest amount of sun tans you; more burns you;a lot may cause skin cancer; and too close to the sun would vaporize you in an instant.

This is a case where the obvious harm of the oil coming ashore seems to me to outwiegh the possible harm of dispersing it in the large volume of the open waters gulf.

A cursory examination of the history of dioxin use here and overseas will reveal the same issues and very nearly the same semantics. I would think the Marine Management studies would be the benchmark studies for dispersant to date-and not only does the Gulf paradigm fail to model tidal rinsing and duration of exposure, the geology of the habitat is grossly dissimilar.

BTW, my brother was boating in Fowl River (Alabama) yesterday. He has property along the river and is monitoring the estuaries. He said that at low tide, the oil-oil mixtures residues carried in on the high tide marked the vegetation along the banks. Be very nice if the chemicals were indeed not harmful.

As suggested in the main post, the toxicity of dispersed oil is mainly due to the effectiveness of the dispersant in increasing the solubility and bioavailability of lighter fractions of the crude: the PAHs and their allies. There's an extensive literature on the toxicity of PAHs to marine organisms. In general terms, the smaller molecules are more toxic and the alkylated forms are the most toxic.

I would to add the news media to the list of those who have done a terrible job of conveying information. I don't understand why we are not seeing a stream of people on the news from industry and academia describing how the problem happened, what are the options to remediate, what is the industry experience in various forms of remediation, impact on the ecosystem(they have done a bit better job here), impact on the economy(again, a bit better job here), health impact of the oil, gas, and dispersants, etc.

There are about 12 universities in the US that teach petroleum engineering. I have to assume at least a couple faculty members would like their names in lights to explain what is going on.

You point out the economic tradeoffs. This should be on the news every night. The world is not simple and I would like to see our news media not feel required to make it simple.

I don't think the dispersed oil will degrade within a short time, though part of it certainly will. The graphs in the main post show that more than 30% of dispersed oil remained in the experiments after 45 days under ideal conditions and with the addition of fertilizer. In the Torrey Canyon spill, which featured the overuse of dispersants near the shore, contamination on the French side of the English Channel persisted for over a decade. I'm thinking that biological effects will persist at least that long in the low energy marshes of Louisiana. Near the shore, shellfish tainting was an important, lingering effect of the Torrey Canyon spill and I'd expect that tainting of oysters, for example, will persist for years in the Gulf.

This is a more grim prognosis than the results observed from the last large Gulf spill, IXTOC-1.


We noticed one of Dr. Humphrey's comments in an oil spill open thread, and wrote to him and asked him if he would be willing to write a post.

It helps to have knowledgeable readers!

This issue is important to me, so I took the time to cart my carcass to the library after a meeting. Where else can you find 25 meters worth of stacks with reports, theses, and studies on our history with fossil fuels, complete with trustee chatelaine (of the secretive smile).

Starting with the oldest, a 1970 PhD out of Woods Hole, KA Burns on Distribution of hydrocarbons in a salt marsh ecosystem after an oil spill, p. 89. The West Falmouth oil spill showed that most sensitive species had high mortality over >5 years in a northern salt marsh and are not able to adapt. “Areas killed by this local disaster were dependent on migration of new stocks from unaffected areas for recovery.”

From the Regional Response Team Working Group, 1986, Oil Dispersant Guidelines for Alaska shows a decision matrix (Fig. 1) with 12 possible decisions. It is only after every other possibility is extinguished that the “request approval for use of dispersants using attached procedures” is even considered. The procedure in Appendix A on whether to approve runs to 4 pages, single-spaced:

Will application of dispersant remove a significant amount of the slick from surface water?
Can dispersants alter the extent or location of shoreline impacts?
Can the damage to endangered or threatened [critters] be lessened?
Will the damage to habitats and resources resulting from chemical dispersion be less than those resulting without chemical dispersion?
If recreational, economic, and aesthetic considerations are a higher priority than natural resources, what is the most effective means of their protection?
Economic considerations include cost of dispersant operation, cost of conventional containment/protection with/without dispersant use, and cost of shoreline cleanup (cost per barrel X number of barrels reaching shoreline) with/w/out dispersant use.


Also from this report, effects of dispersants: Decisions concerning potential dispersant use must be based on an evaluation of potential impacts from dispersed versus undispersed oil since dispersing a slick at one site introduces more oil into the water column than would be caused by a surface slick. This means that effects on water column organisms may be increased at one site so that effects can be decreased or eliminated at other sites.But what happens when there is no there?
Also, For the most sensitive organisms, exposure to hyrodcarbon concentrations greater than 0.1 ppm for 96 hours may result in deathe of 50% or more of exposed organisms It appears that most studies with dispersants use a 4 day exposure measurement.

From 1991, AK Region Oil & Hazardous Substances Pollution Contingency Plan, from the Dispersant Working Group, p.4,In general, the compromise that must be evaluated is between the short-term impacts of introducing dispersed oil into the upper water column, and the long-term impacts of allowing oil to continue to float on the water surface and/or strand. In many cases, adverse effects from chemically dispersed oil are much less than those that result from stranded oil in biologically sensitive areas, or to sea birds or marine organisms that float at the water surface, such as some fish eggs.

Thus, the rationales and logic for using dispersants are all based on history with smaller, isolated spills which can redistribute risk. Unfortunately, in this case, there is no there and thus the logic for use.

From 2002, a ROL Related to Oil Spill Dispersants Esp. Relevant to AK, p. iv (140 studies): There are a number of new toxicity studies. Many of these show that the acute toxicity of chemically dispersed oil is different for different species. In most of the cases, the chemically dispersed oil is somewhat more toxic than the physically dispersed oil. Studies of the food chain show that dispersed oil is more likely to result in the passing of naphthalene through the food chain. Similarly, body burdens of PAHs vary depending on the marine species and whether the oil is naturally or chemically dispersed….Policies concerning dispersants in other parts of the world have not changed significantly since the last report. In Europe, only Britain uses dispersants extensively, although they may be used in Norway and France. No documented use of dispersants has been found in any European country except for the Sea Empress case noted throughout this report. The Baltic countries do not use dispersants and laws against their use are found nationally and internationally in the HELCOM treaties. In North America, several states in the US have moved to allow dispersant use, but dispersants have only been used three times, all of them in the GOM.

From K3d59: A cursory examination of the history of dioxin use here and overseas will reveal the same issues and very nearly the same semantics. I would think the Marine Management studies would be the benchmark studies for dispersant to date-and not only does the Gulf paradigm fail to model tidal rinsing and duration of exposure, the geology of the habitat is grossly dissimilar.

A few more coming, more recent, but this is a start. What it comes down to is the issue of dispersing--to where? The case builds that allowing a corporation bent on hiding its ills (under the rug) should not be trusted to make good judgements in a catastrophe that is so large that previous judgements regarding the ability/ramifications of "dispersing" the problem simply do not apply, because There is no there to disperse the oil to.

Thanks, Iaato. I've been growing weary of tracking this stuff down, throwing it out and watching it vanish.

From Stability and Resurfacing of Dispersed Oil (2005), the process of destabilized oil after initial dispersion is examined. Ultimately, natural forces move the emulsions to a stable state, which consists of separated oil and water…These [processes] include gravitational forces, surfactant interchange with water and subsequent loss of surfactant to the water column, creaming, coalescence, flocculation, Ostwald ripening, and sedimentation.

And from a 2003 thesis from Yale MPH (O’Neill):

EVOS workers who conducted jobs with high oil exposureor reported exposue to oil mists, aerosols, or fumes during cleanup work have a greater prevalence of symptoms of chronic airway disease than workers with less exposure. Nonsmokers with high oil exposure have significantly greater prevalence o f symptoms o f chronic bronchitis than nonsmokers with less oil exposure. High oil exposure was also associated with a greater prevalence of symptoms of neurological impairment, as well as with symptoms of multiple chemical sensitivity. Moderate chemical exposure was also associated with a greater reported prevalence o f chronic airway disease and symptoms of multiple chemical sensitivity.

And from Arlis’ FAQ regarding the EVOS, 11 pages worth of links:

Anyone wanting more can go here:
and do a keyword search using “dispersa”

Finally a June 2010 pub on “Resources on oil spills, response, and restoration; a selected bibliography.”

Finally, from the 1993 EVOS Final Report, State of AK Response, pp. 56 & 69:

"Dispersant" is a very general heading for a group of chemicals or formulations designed to break up large concentrations of oil on the surface into smaller and smaller concentrations. Dispersing an oil spill doesn't make the oil disappear, and dispersants do not necessarily change the oil into something less harmful to the environment. Generally speaking, this class of chemicals disperses the oil into larger volumes of water. In a sense, dispersants dilute an oil slick by taking part of the oil off the surface and distributing it in the upper layers of the water column. Experts generally agree that putting oil into the water column, even in larger dilutions, can have negative effects on fish, plants and smaller animals that live or feed near the surface. One of the principal factors in a decision to use dispersants is whether the immediate harm in the immediate vicinity of the slick is better than having the oil go elsewhere to cause more wide­ spread damage. Dispersants are intended less as a solution and more as a defensive technique. "[T]he principal biological benefit of dispersant use is prevention of oil stranding on sensitive shorelines." states a National Academy of Sciences report on the technique. Decision-makers balance the potential harm of using dispersants against the harm of allowing oil to wash up on beaches, in marshes and in estuaries.

The effectiveness of dispersants, like other methods and technologies, depends on how well the chemicals are mixed and applied, what the conditions are at the site, and what the composition of the oil is at the time. Generally speaking, oil is more difficult to disperse as it weathers. The dispute over the approval and testing of dispersants on the Exxon Valdez spill quickly left the realm of technology and science and leaped into the world of politics, popular media, and legal maneuvering.

The charges and counter-charges received so much publicity that it is impossible to separate the technical information and field reports from the high-level, highly public arguments that included the Governor of Alaska, the U.S. Secretary of the Interior, and the chief executive officer of the Exxon Corp….

And from p. 69,
Corexit never got past the testing stage, for many of the same reasons that relegated hundreds of other products to the file cabinets during the Exxon Valdez response. It had not been tested, scientific data on its toxicity were either thin or incomplete, and it had operational problems. In addition, public acceptance of a new, Widespread chemical treatment was lacking. To landowners, fishing groups, and conservation public and the governments were uncomfortable with Corexit use because no one could prove that the chemical could be recovered Crews would have to be retrained, a monitoring program had to be developed and Implemented, and new concern about worker safety would enter the picture. To organizations, the idea of dumping chemicals on hundreds of miles of shorelines that had just been oiled seemed much too risky, especially when there were other alternatives. Like the earlier public flap over dispersants in April and May, the bitter arguments about Corexit were based, in part, on Exxon's insistence that it had an answer to the oil spill and the government was obstructing progress. A high-ranking Exxon executive bitterly complained to a US. Senate subcommittee in July that despite overwhelming evidence of Corexit's effectiveness, the State of Alaska would not allow the chemical to be sprayed. The executive said he wasn't sure Alaska even wanted the spill to be cleaned up quickly," since the DEC wouldn't grant approval to use Corexit. Again, like the dispersant debate, the issues and facts about Corexit were not as clear and easily defined as any side would have liked, Exxon's experts stated that the toxicity was low, the cleaning efficiency was high, and their ability to recover the chemical and oil was good. State and federal environmental scientists (including DEC, Fish and Game, and EPA) felt that the toxicity information was limited and incomplete, Both governments agreed that Corexit took oil off the rocks, but neither felt that Corexit was much more efficient or less disruptive than hot water, And most observers had serious questions about the ability of Exxon crews to contain and collect the oil-water-Corexit mixture that washed off the rocks into the water. [0 most of the 1989 tests, Exxon used more chemical- in at least one case, twice as much chemical- as it could actually recover.

Did Corexit get oil off the rocks? The answer, according to state and federal observers, was yes, although it worked better under dry conditions. Could Exxon recover the mix of water, oil and Corexit once it was in the water? Not so well, the government observers said. "There is little evidence to indicate that an appreciable amount of washed oil (let alone the applied Corexit) was recovered after the test applications," the EPA reported,4B State and federal observers reported that Corexit tests generated a reddish-brown plume that sneaked outside containment and absorbent booms and was difficult to recover, Federal and state agency staff, including EPA and the state Department of Fish and Game, were not satisfied with the limited information available on the toxicity of Corexit. The existing tests told regulators something about the acute effects of Corexit, but they were silent on the effects of longer-term exposure -a critical point if Corexit were to be used in large quantities covering hundreds of miles of various wildlife habitat. There was also little firm information about the longer-term effects of a mix of Corexit and oil on wildlife -again, a critical point, considering that Exxon had not demonstrated its ability to contain and recover what it washed off; the elusive reddish­ hrown plume was troubling.

In short, the public and the governments were uncomfortable with allowing a chemical dispersant to be sprayed throughout hundreds of miles of the spill area because no one could prove that the chemical could be recovered, Crews would have to be retrained, a monitoring program had to be developed and implemented, and a new concern about worker safety would enter the picture.

Finally, not CoRexit in this study, but all dispersants are similarly harmful, the authors state. Again with short term exposure only. Short and Long Term Toxicity of Crude Oil and Oil Dispersants to Two Representative Coral Species. Shafir, Shai; Van Rijn, Jaap; Rinkevich, Baruch. Environmental Science & Technology, 8/1/2007, Vol. 41 Issue 15, p5571-5574, 4p; DOI: 10.1021/es0704582; (AN 26152806)

Oil dispersants, the tool of choice for treating oil spills in tropical marine environments, is potentially harmful to marine life, including reef corals. In a previous study, we found that dispersed oil and oil dispersants are harmful to soft and hard coral species at early life stages. In this broader study, we employed a "nubbin assay" on more than 10 000 coral fragments to evaluate the short- and long-term impacts of dispersed oil fractions (DOFs) from six commercial dispersants, the dispersants and water-soluble-fractions (WSFs) of Egyptian crude oil, on two Indo Pacific branching coral species, Stylophora pistillata and Pocillopora damicornis. Survivorship and growth of nubbins were recorded for up to 50 days following a single, short (24 h) exposure to toxicants in various concentrations. Manufacturer-recommended dispersant concentrations proved to be highly toxic and resulted in mortality for all nubbins. The dispersed oil and the dispersants were significantly more toxic than crude oil WSFs. As corals are particularly susceptible to oil detergents and dispersed oil, the results of these assays rules out the use of any oil dispersant in coral reefs and in their vicinity. The ecotoxicological impacts of the various dispersants on the corals could be rated on a scale from the least to the most harmful agent, as follows: Slickgone > Petrotech > Inipol = Biorieco > Emulgal > Dispolen.

Isn’t this enough? The Final Report to the State of Alaska is the most damning indictment, with page after page of explanations why the Response Team opted not to use dispersants, due to dangers of toxicity. And somehow in the past two decades, the idea of not using dispersant unless you could recoup it has morphed into free license for a foreign corporation to pump almost 2 million gallons of dispersant into the GOM over 90 days. Are we insane? Research and a little history can emancipate us; my favorite weapon of choice. The link again:

Enhanced crude oil toxicity to coastal organisms due to the use of dispersants was one of my take-away messages from hanging around the fringes of the spill response community for the better part of two decades. The Canadian policy for dispersant use was once pretty similar to Alaska's but I'm out of the loop now.

The Sea Empress and similar cases are causing Europeans to re-evaluate the potential benefits of dispersants, and increase the pre-approvals for such use as this article describes:


From K3d59: A cursory examination of the history of dioxin use here and overseas will reveal the same issues and very nearly the same semantics. I would think the Marine Management studies would be the benchmark studies for dispersant to date-and not only does the Gulf paradigm fail to model tidal rinsing and duration of exposure, the geology of the habitat is grossly dissimilar.

Dioxin per se has never been used anywhere. This class of dangerous compounds are a trace contaminants present in a variety of synthetic and natural materials. They are by-products in the manufacture of organochlorides, or are formed in incineration of chlorine-containing substances such as PVC (polyvinyl chloride), in the chlorine bleaching of paper, and from natural sources such as volcanoes and forest fires.

I wondered how dioxins got into this discussion too and don't see how their environmental behaviour and fate has light to shed on oil spill effects. I guess they could be, probably are, an ultratrace component resulting from the low temperatures typical of in-situ burning. There's a lot of chloride in the ocean.

For the record, though, dioxins were an unintentional component of Agent Orange, were applied with it in Vietnam and Cambodia and were stored, spilled onto land and into water, and so on. Here's a link to the abstract of one of a series of papers by a Canadian consultant.

The discussion above is very good, it'll give people an excellent reference to argue based on facts and educated opinion.

Have you considered mailing it to Anderson Cooper and the other TV personalities who seem to apply hysteria rather than reasoning to their coverage?

Now I'd like to make a suggestion:

Maybe they should investigate the toxicity of biodegraded oil, rather than the oil itself? The information I have seen shows the light fractions evaporate, some dissolve in the water, and quite a bit is eaten. But there's a heavy fraction left over, and this fraction seems to stick around for a long time. So the question should be, once you biodegrade the oil, and the leftovers become mousse and tarballs, what is their size distribution (ie what's the size of the colloidal particles), what's their tendency to clump up, and so on? I imagine a tarball is a lot harder for a fish to swallow than a few cc of oil, if the oil is found in very low concentrations.

Also, since I'm an engineer, I have a tendency to think in "industrial strength" terms. For example, what do you think of the use of fire on the marsh near the coast to just burn the oil off? I've seen quite a few videos of the crude lapping the marshes in Louisiana - although I suspect CNN in particular likes to show the same clip over and over, because I'm starting to recognize the little leaves and individual plants by now.

But IF the oil is only penetrating a few feet at this time, wouldn't it be better to go by with a hot flame (say a propane fired flare) and burn the oiled marsh, the oil on the water, and anything that comes close to being hydrocarbons to a crisp? Evidently this has to consider erosion and so on, but I think it's better to burn the heck out of it now, rather than wait for a storm to pick up that mousse and drive it far inland. Is this a crazy idea?

I write in defense of Anderson Cooper and his alleged "hysteria." It is not that, but merely a speculation tinged by an entirely reasonable hermeneutic of suspicion directed against BP and the Federal Governmnent. The fact that there exists rampant and very confusing speculation about the spill and its effects is almost entirely the fault of these two entities. So, if there is "hysteria" about the spill in certain quarters, then please let's not blame those who speculate, but rather those who self-servingly keep the speculators in the dark about the truth.

Do you really think that full disclosure would stop the speculation? Look at the history. We have various national events like 9/11 that have been very carefully documented and yet the alternative theories are still rampant.

QUOTE---[-] Speaker To Animals on July 14, 2010 - 3:58pm Permalink | Subthread | Parent | Parent subthread | Comments top

Do you really think that full disclosure would stop the speculation? Look at the history. We have various national events like 9/11 that have been very carefully documented and yet the alternative theories are still rampant.----UNQUOTE

The official story says a few guys in turbans did this. Yeah, right.
Before you explain how Building 7 collapsed at 5pm......start here and good luck.
1225 architectural and engineering professionals....

Thank you for illustrating my point so vividly.

I'm not impresssed by his hysteria. I also found some of their comments to be distortions if not outright lies. That's his style, seems to be what CNN wants from the guy, and he dishes it. Since I'm an old timer, I find the current crop to have a much lower quality than the newscasters we used to have say in the 1960's. This applies to Mr Cooper, but also to Rachel Madow, Keith O. and to their Fox News counterparts, who are even worse.

For example, there are oil impact maps prepared and distributed at the DW Horizon response website. They COULD show those maps, then show us flyovers and close ups. There's no need for Cooper to whine like a 5 year old because they can't approach a boom within 60 feet - something also happen to know was a lie, because they COULD have the permit to approach the boom if they asked for it. I'm also sick and tired of watching them show the SAME shot of the same 50 square feet of oiled marsh. What's the matter, they don't have the money to go take a new shot?

I don't want to muddle this site with my overall impression of the lousy work being done by the US media in the last 20 years or so. Maybe they were always lousy, and I got smarter. Or maybe they HAVE been dumbing down their coverage to the point it seems to be disinformation 101 for 12 year olds. But it is really really bad, and Cooper deserves to be tar and feathered for his lack of professionalism. I forget who had that job before him, it was a black haired older fellow they fired during the Iraq war coverage. I thought he was a lot more professional.

fd: Right, it would be great if someone with a background in toxicology or the health professions would take a shot at summarizing what's known about toxicity of the mousse and tarballs.

Re burning weathered oil in place at the marsh edges: There's lots known about this. Many universities have experts the press could consult, such as Dr. Qianxin Lin at the LSU Wetlands Biogeochemistry Institute or Dr. Reza Pezeshki at the University of Memphis Biology Department. And coastal-state environmental agencies have excellent scientists on staff with experience in marsh ecology and management. Some states even have formal policies on saltmarsh management.

One reality about oil at the marsh edge is that some is quickly buried in the mud by burrowing invertebrates, which are constantly digging homes for themselves and emerging at the mud surface to feed, etc. Buried oil will persist for years or decades.

The primary methods for treating crude oil spills are mechanical removal, burning in place, chemical treatment, and bioremediation. Each involves tradeoffs between reducing the amount of oil (and its immediate damage) and the longer-term toxicity of the oil.

Mechanical removal has proven quite damaging to the vegetation, causing erosion of the substrate and enhanced penetration of oil into the mud.

In-place burning removes the vegetation, which takes several years to recover. Of course, the fouled plants may die anyway. Fire also can scorch roots and rhizomes in exposed mud and hence prevent plant recovery. Removal of the plants aboveground and/or subsoil can lead to erosion of the marsh. There's the potential for the numerous dead stems present to carry a fire across the whole marsh, exposing the whole system to destruction in subsequent hurricanes.

Dispersants have been applied to marsh and beach oil deposits too, but they are not as effective as when applied in open water because mixing with water is not as good in this situation and the oil has already been partly biodegraded before landing. This also is a consideration perhaps for adjacent bays/bayous/rivers.

Bioremediation is like what we've already considered in open water. On the marsh edge there are plenty of oil-eating microbes. In the one marsh study I know of (Nova Scotia), nutrients were limiting, so addition of fertilizer made a big difference in the amount of biodegradation that occurred. Once concern is that fertilizing the marsh edge could cause eutrophication of adjacent waters.

A final alternative is to take no action (the fancy term - natural attenuation - may sound better). This may be the best approach because the alternatives have known detrimental side effects or unknown effectiveness.

I'd like just to add that the exposure of nearby people to air-borne soot particles, the product of incomplete combustion at in-situ burning operations, is a serious concern for public and occupational health officials. These particles can be expected to contain small amounts of carcinogens.

Thanks very much for your post, Dr. Humphrey!

I was wondering if you have any comment on the BP dispersant letter, which describes its review of the available dispersants. It says:

COREXIT does not contain chemicals that degrade to NP [nonylphenol]. The manufacturer indicates that COREXIT reaches its maximum biodegradability within 28 days of application, and that it does not persist in the environment. These qualities make COREXIT a better choice [than Sea Brat #4] for subsea application, based on the information currently available. COREXIT appears to have fewer long term effects that the other dispersants evaluated.

The BP dispersant letter seems self-explanatory. There are two problems with interpreting it, however. One is the redactions, which might be noteworthy depending on what's redacted. The other is that it's difficult to understand aspects of the dispersants' behavior in the environment, beyond acute toxicity to the two test organisms, because of proprietary information on many of the dispersants and because few of their other behaviors in the environment appear to have been tested. I agree that a nonylphenol precursor in one of the dispersants adds a concern about endocrine-disrupting action for that product.

Certainly the subsequent EPA report on toxicity of dispersants, excerpted below by Bennett, provides additional and welcome insight on acute toxiticy.

The "elephant in the room" IMO remains the toxicity of oil and oil-plus-dispersants, to a wide variety of organisms. I'm really looking forward to seeing the EPA report on this subject in a couple of weeks.

Hoisted from the EPA report:

The U.S. Environmental Protection Agency released preliminary data Wednesday from its own toxicity testing for eight dispersants in a bid to corroborate potentially suspect industry-provided results. But questions remain about the safety of these chemicals that can be used to break up oil spills, including COREXIT 9500, which is being employed on a massive scale by BP in the Gulf of Mexico. The agency's results showed broadly similar impacts on silverside fish (Menidia beryllina) and mysid shrimp (Americamysis bahia) across a range of concentrations. And none of the dispersants showed significant capacity to disrupt the hormonal systems of animals, at least at the cellular level.

EPA dispersant tests show limited toxicity but questions remain

I'm a lot more interested in the toxicity of a combination of Corexit 9500 and Macondo crude than I am in the toxicity of the dispersant alone. I hope those data, too, will be in the report.

The sad part of all of this discussion is the study of Corexit's toxicity is being conducted now, in the Gulf, on a massive, real world scale, with the native fish and animals the test subjects. The early studies say the dispersants are "less toxic" than oil; that's a meaningless distinction, though. If the difference is less than 10% in toxicity, for example, is there really a difference?

It's a shame that the questions now being asked about the dispersant, combinations of dispersant and oil, etc, are only now being studied, rather than the answers found in a laboratory prior to this disaster taking place.

It's a shame that the questions now being asked about the dispersant, combinations of dispersant and oil, etc, are only now being studied, rather than the answers found in a laboratory prior to this disaster taking place.

You think?!

BP was getting a 250,000 dollar a day tax write off to cover 70% of the rent for the Deep Water Horizon. You think the F'n Oil Companies could afford to foot the bill for some independent scientific research now and then. I say take away all their damn incentives and tax breaks and give it all to Institutes doing marine science and oceanographic research in the Gulf!

When the Deepwater Horizon drilling platform set off the worst oil spill in American history, it was flying the flag of the Marshall Islands. Registering there allowed the rig's owner to significantly reduce its American taxes...

...Transocean, moved its corporate headquarters from Houston to the Cayman Islands in 1999 and then to Switzerland in 2008, maneuvers that also helped it avoid taxes.

At the same time, BP was reaping sizable tax benefits from leasing the rig. According to a letter sent in June to the Senate Finance Committee, the company used a tax break for the oil industry to write off 70 percent of the rent for Deepwater Horizon -- a deduction of more than $225,000 a day since the lease began...

...But an examination of the American tax code indicates that oil production is among the most heavily subsidized businesses, with tax breaks available at virtually every stage of the exploration and extraction process.

Yet there is no money for investing or giving tax breaks and incentives to renewables either.
I know we can't afford to invest in any of that stuff! I think it's past time for some very big heads to roll!

There are antitrust laws that prevent companies from operating together, and it is difficult for individual companies to fund these studies (except as grants to universities).

A better way, if we really want decent studies on subjects such is this is to have federal programs that do the research (with the actual research perhaps done in university programs). These could be funded by oil tax dollars.

I think the same thing is true for food issues. Everything we read says that a lot of the food we eat is not very good for us. Yet the hands-off approach leaves the buyer stuck with the status quo.

Gail, my comment was mostly intended as a rant about the fact that Oil companies get massive tax breaks and incentives. I at least would like to see changes at the Federal level towards eliminating many of those breaks and incentives. At the same time I would like to see much more Federal money in the form of research grants being funneled to various Universities and research institutions to do pure independent science.

Even if BP or other Oil companies were so inclined I would much prefer that they be out of the direct loop with regards providing grants to fund research that could conceivably come up with results that really might not be in their self interest.

In a similar vein I wouldn't be very comfortable with cigarette companies providing grant money to Universities to do research on the correlation between lung cancer and cigarette smoke unless very clear safeguards were put in place to avoid conflicts of interest. Even if they were there might still be ways for whoever is providing the funds to apply subtle forms of pressure...

Money may still talk but the threat of suddenly withholding it could just as easily be used to silence someone...

These could be funded by oil tax dollars.

oil taxed before or after it has payed dividends to the shareholders and big bonuses to the managers?

Get some big mea culpa no strings attached oil company grants for research now while the skillet is hot...down the road it will be much harder to do. The science foundations should be hitting up every big oil player they can right now, a little positive PR attaching the grantors to the research being or to be done might be very tempting bait at this moment.

If the difference is less than 10% in toxicity, for example, is there really a difference?

I don't think anyone can say Corexit is effectively more or less toxic than the BP spill contents. Corexit is mostly hydrocarbon, in this case kerosene. As such the toxicity profile is going to be similar (with variations based on the composition).

One thing to look at though is the relative proportions of the two. The ROV videos hold a clue. The little stream of white stuff is the Corexit. The billowing clouds of brown stuff is the oil. Any additive effects are clearly not going to be important given the discrepancy in volumes.

What is clearly much more important is the interactions. Corexit changes the physical form of the oil in water dispersion, and that has profound implications as to the effect of the oil in water on the environment.

There is a very fundamental principle of physical chemistry - once you get the surface area to be very large, surface effects, that is processes that depend on surface area become predominant. That's what Corexit is doing here - by dispersing the oil you are getting vastly increased surface area and that means the what is going on is dominated by that surface area. In general this means diffusion, that is interaction between the oil and the surroundings will occur much faster. So bio-degradation will go much faster (and consume oxygen more rapidly). It also means anything else in the vicinity of the oil drops will come to equilibrium more rapidly. That explains the increase in adsorption of toxic compounds like PAHs in organisms exposed to the dispersed oil. Eventually of course the concentration of toxics will reach the same level with non-dispersed oil, but it will take longer.

So like all things it's a balance. Unfortunately the literature in this field doesn't address the real complex systems and as a result decisions are being made with incomplete information. But that's life. If you could see the future with complete clarity you would not be human. You just have to muddle through. Personally I think the idea of keeping the oil off the surface is worth the attempt. After all that's where the life concentrates.

BP made the decision on what to do, not the EPA. The EPA just appears to be along for the ride. The EPA is just as incompetent as all the other federal agencies compromised by corporate influence. I would have never allowed the use of dispersants, but that's my opinion. A small spill dispersed disappears. A large spill dispersed will kill everything in a large volume of water till the concentration gets low enough. How big is the dead zone around the well? Also I believe the disperants make the chocolate blobs less likely to float nicely on the surface which makes skimming and booms ineffective. Instead of oil floating nicely on the surface the top portion of the ocean is a chocolate blob soup. This is a real time massive scale experiment. I just hope we get objective science instead of science tainted by BP funding pressures.

This is a remarkable site. I have no expertise...just a 'horrified' observer to the ongoing nightmare. But I am rather shocked at the view taken by the expert citing studies on Corexit when all of this has been publicly accessible:

In Gulf Spill, BP Using Dispersants Banned in U.K. - ProPublica
May 17, 2010 ... We learned about the U.K. ban from a mention on The New York Times' ... BP has defended its choice to use Corexit. A BP spokesman called the ...
Corexit: BP Using Dispersants In Gulf Banned In U.K. For Being ...
May 18, 2010 ... Dispersants: EPA Informs BP To Use Less Toxic Chemicals To Break Up Spill .... little as 2.6 parts per million has been banned for use in the UK since 1998 ... Coreexit is not banned in the UK except on rocky coastlines. ...
City Brights: Yobie Benjamin : UPDATED: BP oil spill Corexit ...
Jun 28, 2010 ... The UK's Marine Management Organization has banned Corexit so if ... fin tuna and shrimp, use the wetlands at some point in their lifetime. ...
BP Oil Spill Corexit Dispersants Suspected in Widespread Crop ...
BP has been banned from using Coreixit for leaks by Britain. ... signs point to BP's use of aerosolized Corexit brought inland by the ocean winds or rain. ...
BP Dispersant Banned in UK – Corexit 9500 : The Green Trash Can ...
Jun 28, 2010 ... The UK's Marine Management Organization has banned Corexit so if there was a spill in the UK's ... Five Ways to Use Eggshells in Your Garden ...
BP: We Have to Use Corexit Because No One Tests for Endocrine ...
May 24, 2010 ... Today on Democracy Now, Amy Goodman reported in her intro that Corexit has been banned for use in Britain. I see HuffPo cited the same thing ...
Post Carbon: EPA demands less-toxic dispersant - Juliet Eilperin
May 20, 2010 ... BP has been using two forms of dispersants, Corexit 9500A and ... Britain banned some formulations of the dispersant Corexit more than a decade ago. .... "Of 18 dispersants whose use EPA has approved, 12 were found to be ...
pas au-delà: Corexit: banned in the UK for a reason
May 27, 2010 ... Corexit: banned in the UK for a reason ... BP has defended its choice to use Corexit. A BP spokesman called the product [5] “pretty ...
Oil spill treatment products approved for use in the United Kingdom
File Format: PDF/Adobe Acrobat - Quick View
This list has been compiled by the Marine Management Organisation as a guide to the range of oil treatment products currently approved for use in the UK. ...
BP's Dispersant Corexit Banned in UK for 10 yrs. ? Info here ...
Welcome to a Facebook Page about BP's Dispersant Corexit Banned in UK for 10 yrs. ... BP has defended its use of Corexit, spokesman Jon Pack claiming it is ...

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Plus...the marine researcher from U Georgia (found her blog in Jeff Masters Weather Underground Blog) as well as other marine toxicologists and researchers have reported shockingly low levels of oxygen and huge dead zones. How this information was conveniently overlooked while discussing exactly that possible outcome is...rather shocking.

And then there is the perceived wisdom in Europe--and apparently the rest of world-- that getting the oil up rather than sinking it is the most efficacious way to collect it.

Even a lay person can comprehend the logic of this.

This information has been widely disseminated in many news stories. I apologize for not going back and providing all the links as I am sure everyone reading this is familiar with them.

I would like to ask WHY anyone would try to present an argument in favor of Corexit? Why? Why? Why?

This conundrum reminds me to haul out a most prescient observation by made years ago by RD Laing:

..."Science as it is practiced today, has no way of
dealing with consciousness, or with experience, values
ethics or anything referring to quality. This
situation derives from something that happened in
European consciousness at the time of Galileo and
Giordano Bruno. These two men epitimise two
paradigms--Bruno who was tortured and burned for
saying there were infinite worlds (and theoretical
physics has now come to the same conclusion); and
Galileo who said that the scientific method was to
study this world as if there were no consciousness and
no living creatures it it. Galileo made the statement
that only quantifiable phenomena were admitted to the
domain of science--he said whatever cannot be measured
and quantified is not scientific and in post Galilean
science this came to mean whatever cannot be
quantified is not real.

*****This has been the most profound
corruption from the Greek view of nature as physics;
which is alive, always in transformation and not
divorced from us. Galileo’s program offers us a dead
world: out go sight, sound, taste, touch and smell,
along with them have since gone aesthetic and ethical
sensibility, values, quality, soul, consciousness,
spirit. Experience as such is cast out of the realm of
scientific discourse.

Hardly anything has changed our world more during the
past 400 years than Galileo’s audacious program. We
had to destroy the world in theory before we could
destroy it in practice"*****

*****could be BP's corporate mission statement

Get all your horrifying oil spill news here: Desdemona Despair.

I think part of the problem with this oil is that being down so deep, and being the type of oil it is, it tends to mix with the water to form a "mousse" even without a dispersant. At least that is what I remember of the first reports of the oil that was being found. So this particular oil was hard to skim from the very beginning, even without adding dispersants. If the oil had been from shallower wells, as in Europe, it might have been easier to skim--and the general wisdom from Europe might have been right.

So the questions is--given the particular oil we have here, that it coming out of the well one mile down--what is the best thing to do. The experts are saying add dispersant, so the oil will tend to mix with the water even to a greater extent. According to the studies quoted in the post, it will biodegrade quite a bit more quickly, with the COREXIT added.

The result is clearly not great. The question is whether it would have been even worse without dispersant--and the general belief among the scientist who have looked at this is that it would have been worse without the dispersant.

Gail and Barrett are correct: Corexit 9500 failed the UK limpet test, because limpets couldn't cling to rocks when exposed to Corexit. The UK agency did no tests in the open ocean, so their dispersant approvals are not relevant to the open-ocean environment. The harm to limpets is meaningful where limpets live, and not allowing Corexit to be used on the UK rocky shores is the appropriate policy.

It's clearly important to know what specific harms occur. That's why I called attention to coral death from other dispersants, even though whether coral is killed by Corexit is apparently not known--we need research to find out.

The levels of oxygen found in the oil plume are not shockingly low. They are reduced somewhat by the metabolism of oil-eating microbes, not low enough to threaten animals that require oxygen. It's fine to be concerned about the possibility and look further to see if the concern is warranted. It's not fine to ignore what we know.

Please supply links to research information on dead zones. As far as I know there have been no such reports in any of the studies done so far.

Look up "dead zone in Gulf of Mexico" in Wikipedia. It's not related to oil, though...

It's not related to oil, though...

Obviously that is not what I am asking about.

Just because you can find a lot of hysterical dispersant letters doesn't mean they are necessarily right.

UK does not permit the use of Corexit on rocky shorelines because it may make rocks too slippery for snails to climb up. There is no general ban, according to the link I gave. I don't think rock shorelines are a particular problem along the Gulf of Mexico.

One of the issues that BP looked at was what products were actually available and their toxicity--see the BP letter to the EPA. When it looked through the EPA approved dispersants, it could not find any that were better, and actually available in quantity. The EPA apparently agreed.

Thank you for posting this and referencing the work that BP did in response to the EPA order- I was just about to start looking up the same.

If there's one thing I hope comes out of this episode, it will be a renewed respect for the infrastructure, experience, expertise, and wisdom that can be gathered from industry as opposed to the back of the napkin analysis and calculations of bureacrat scientist and policy wonks. When someone has spent much of their life addressing problems, they tend to understand the gotchas and unintended consequences of certain actions.

The government and wonks should spend their time dreaming up nightmare scenarios and then asking industry to explain how they're going to error-proof them- and then punishing those who make stuff up.

If there's one thing I hope comes out of this episode, it will be a renewed respect for the infrastructure, experience, expertise, and wisdom that can be gathered from industry as opposed to the back of the napkin analysis and calculations of bureacrat scientist and policy wonks. When someone has spent much of their life addressing problems, they tend to understand the gotchas and unintended consequences of certain actions.

While I may, actually, over time, develop an immense respect for the fox's accumulated expertise in raiding the chicken coop and while the fox probably does tend to understand the gotchas and unintended consequences of getting caught stealing the chickens, I'm not about to agree that that would make me want to hire said fox to be the actual guardian of the darn chicken coop.

I think I'd still very much like to have the independent expertise of my loyal hunting dog scientist with his back of the envelope barking to warn me that the fox is up to something and it may have a lot to do with why my finest birds keep disappearing. I'll also keep my trusty old shotgun loaded and ready to shoot as soon as my dog scares that fox out into the open...

Good info, Gail,

Also, while we're at it, the above post that suggests a "massive" reduction in oxygen ought to be corrected. As you'd expect, organisms that break down hydrocarbon are feasting away in the water column (hurray for them), and there is some oxygen attenuation that accompanies that. Looking at the graphs shown in the UG site:

the relative oxygen falls from a value of about 6 to a value of about 5.5, or less than 10%, in the presumptive plume. That's going to be stressful for high-rate consumers of oxygen (tuna, for example), but it isn't a dead zone as found elsewhere in the Gulf:

I suppose we'd all like to see a better world in which oil spills did not happen. Failing that, let's find the gumption to see the value of finding the least-worst circumstances. With dispersants oxygen levels fall in certain sectors of the water column. But, imagine if BP failed to use dispersant: much more oil on the ocean's surface (bad), slower degradation of the hydrocarbons (worse), and vastly greater devastation to the marshes (tragic). Who wants to go there?

UK does not permit the use of Corexit on rocky shorelines because it may make rocks too slippery for snails to climb up

Yeah, why would anyone care whether or not some stupid snails can climb up and down the rocks along the shore. Hey I have some limpets and snails in my salt water aquarium should I add a couple of drops of Corexit to keep them from climbing up the sides of the tank? I'm sure it wouldn't harm their tank mates, BP says they'd be must be so.

I hate to say this but what you have presented is a pile of media hysteria including links to sites known for sensational reporting. None of this rises the to the level of study presented by the article author.

Yep, providing sources like Natural Remedies and HuffPo(I don't know the rest) for any science related discussion tends to discredit the argument. Both of those site's integrity was surrendered long ago... if Natural Remedies ever had any...

Excellent coverage of the subject area, Dr. Humphrey - you've brought much light to an area we've only heard soundbites of. Thank you!

The June 14, 2010 issue of Chemical &Engineering News, the weekly magazine of the American Chemical Society has an article on page 15 by Jeff Johnson and Michael Torrice that includes information on the dispersants in Corexit 9500. It is a mixture of sodium dioctyl sulfosuccinate (an ionic detergent) and a combination of the nonionic detergents in the Span and Tween families. Tween 80 is a derivative of polyethylene glycol with a tetrahydrofuran core and an oleic acid ester on one OH group. I suspect both of these compounds would be tasty to the right microorganism. With a tetrahydrofuran (THF) core the Tween would be rapidly air oxidized to form first hydroperoxides and then a cascade of smaller, easy to metabolize fragments. The hydroperoxides, a cousin of hydrogen peroxide, would have some toxicity but the concentration would be so low (less than the active oxygen species you have in your backyard swimming pool) that the effect would be less than the toxicity of the oil. In short, the dispersants have lots of chemical handles that can lead to their breakdown. Oil has few handles and is far more persistent.

Years ago I was involved in unpublished experiments to look at the toxicity of several non-ionic and cationic surfactants (a dispersant is a surfactant) to fish. I remember being awestruck by the power of one of the non-ionic compounds, which caused massive mucous secretion on the gills and erosion of the gill tissue, effectively drowning the fish. The concentrations I remember were higher than would be found anywhere other than very close to the release point at Macondo, though, but the range of expected effects would be broad.

The full text of the Chemical & Engineering News article is available here:

My biggest problem is not the tradeoff between toxicity of the dispersant versus crude oil. It is the fact that the oil and dispersant is introduced to areas where there is no or little research as to what it does in these environments. Additionally, there are no known means to treat this mix sub-surface. At the surface there are at least some means to deal with the oil. My experience is that trading off a known effect to one there is very little known about , seldom turn out to by of any advantage.
BP's motivation is clear, by the time the effects might be understood, they are either no longer around or it will be difficult to link them to it. It will be at best circumstantial evidence.

I'm also interested in Humphrey's opinion about the effect of dispersant on our ability to remove oil from the ocean. I mean, Corexit might be less toxic than oil and enable faster bacterial degradation... but almost completely prevents us from scooping the oil from the sea.

With all of the oil floating to the surface birds would probably be more affected, hurricanes would probably be a bigger concern (not sure about this), and BP would be obliged to give breathing masks to all the people working there...

...but what about marine life?

Wouldn't it be better if the affected area was almost exclusively the sea surface? Wouldn't it be better if there was limited bacterial oxygen depletion? To my (layman) eyes, it's also much easier for a fish to be fooled and swim inside a foggy mixture of toxic oil and corexit (breathing it), rather than avoiding a big oil patch.

Does this make sense to anyone else?

PS: Sorry for my english.

The problem with this idea is the sea surface and the marshes and estuaries are where by far the majority of life in the Gulf resides. And skimming/collecting oil is not a very efficient process. Marshes are essentially impossible to clean in any meaningful way. Oil on the surface is exactly the place where it will do the most harm because that's where the density of life is the highest.

Plus if you read the Dispersant Working Group report you will see that the life living at the surfaces is more complex than in the deeper ocean which suggests that it will recover much more slowly. A generation of Brown Pelicans takes far longer to mature than a simpler organism as those that typically live in the deeper ocean.

Thanks Gail and Dr. Humphrey,

It is sincerely refreshing to note that there are people actively looking at the data on this issue (be it complete or no something is better than nothing)

I agree about the trading bad for bad however but at least the data doesn't look as bad as the fearmongering does.

It seems to me that one way of reading this keypost is: Dr. Humphrey has carefully and skillfully disguised his promotion of dispersant use in a post designed to read as an objective overview. IMHO, he has seized nearly every opportunity to do so since discussions about the subject started here.

He has concentrated his focus on physical degradation of oil, largely ignored studies suggesting significant additional harm to organisms exposed to dispersed oil (while citing one with contrary findings) and studies showing little to no difference in biomass recovery at 12 weeks in a Louisiana marsh exposed to WAF of crude vs. dispersed oil—despite repeated citations in these discussions.

I don't know if he has a particular bias, deliberate or otherwise, or if he has considered and dismissed, without explaining, the concerns I and others have raised and which seem potentially quite troubling. I do think his post should be read with some skepticism.

There is a physical reality of NG content: A barrel and a half of oil at the well head expands to 1 barrel of oil and 2000+ cu ft of natural gas at the surface. All of this happens as the gas expands while oil flows up free through water layers. So the high moleculare weight fractions might emulsify deep underwater and stay there thanks to higher density, and only lighter fractions (also not as stable emulsions) surface if left completely alone (i.e. float freely 5000 ft up). Addition of dispersant only helps process that happens anyway. Quite possibly Dawn would work well, too :-)

A side questions: Flow through riser keeps gas and oil pressure under control - I am wondering what is the pressure on top of the riser (sea level). I mean the oil gas mixture is entering degassing process at what kind of pressures.

A side-side question. Can flow during blow-up due to gas expansion become supersonic?

I'm generally cautious of any bureaucratic issuance, but I'm going to credit Paul Anastas for his caveat, which seems to be overlooked every time the EPA June 30, 2010 preliminary results are brought up. Of course I could be cynical and point out that this is an excellent CYA statement as well.
"...Let me be clear about another point as well: this first round of testing studied specific effects under specific conditions. These data provide information on only some of the variables that we must consider. We are going to need more testing to get a full picture of dispersant impacts, and make any determination as to whether one product ranks better or worse than another under all of the conditions of its use."

I think you have summed it up pretty well, Curious Canuck. (Sorry, I seemed to have missed the button that would have put my reply with yours.)

And...the issue of oil being naturally fragmented because of its release in a deep water environment is understood by this poster.

I am still just in wonder at the rationales that can be snapped out of the thin air in order to roll over reality. I suggest those that keep saying things like well...just because the limpet looses its grasping ability (and presumably all the physiological distress that aberration implies) doesn't mean it might kill my child or a baby dolphin-- might be persuaded to read the quote from RD Laing I offered up. He nails this 'rationalist/quanitifiable' pathology and shows it up for the symptom of a collective pathological condition that it is.

Some of the work is being done on Dr Humphrey's home turf. Hopefully he'll keep us posted.

I suspect that domoic acid has been eliminated already as a causative agent. If the humans who continue to eat seafood start dying, we can say eureka!
"...Much of the evidence in the turtle cases points, in fact, to shrimping or other commercial fishing, but other suspects include oil fumes, oiled food, the dispersants used to break up the oil or even disease...."

As far as I can tell by reading this article they don't have a clue at all as to what is causing these animals to die. The autopsies are completely inconclusive.

Certainly there is nothing here that could be used in court against BP. And nobody is talking about the baseline data - what the normal rates of dead sea creatures washing up to the beach are.

Without that information it's going to be very difficult to hold BP accountable for anything.

Please note: the EPA studies cited above were for short periods of time: up to 96 hours. We are looking at a situation closer to 96 days. Even they said

"Short-term acute toxicity tests using consistent methodologies and test organisms provide important and fundamental information on oil spill dispersants and other toxicants."

There have been reports of Corexit being sprayed at night, even over manned boats. If true the reason would likely be to NOT BE SEEN as spraying at night would make it harder to be sure you were spraying what you are supposed to be spraying (open ocean with actual oil on it vs humans on boats).

BP has done cover up after cover up. The Corexit hides surface oil, night spraying if proven to be true hides spraying. It becomes harder and harder for us to believe that any decision they make is not about BP's bottom line. Oil can be skimmed from the surface, if booming is done write we learned here on the oil drum, it can effectively collect oil near the shores, but out of sight out of mind. Whether or not Corexit is the best choice, we can be sure that it is BP's choice because it hides the oil from the public, just as surely as media and citizen bans on getting near the oil do. Danger here folks, don't come near, especially with a camera, we just want to keep you and your camera safe.

I cannot join the technical side of the debate on dispersants. But what is totally clear to me is that the decision to use them or not should have been made by a panel of scientists whose reputations were on the line, and whose incomes and grants were in no way dependent on BP or even the oil industry (hard to find maybe.) And the panel should have included some of the sharpest critics to make sure all voices were heard.

But I do not blame BP first and foremost, BP's actions are based on the bottom line, and nothing else, we know that. No, I first and foremost blame our gov't for not stepping in on day one and taking control and responsibility. It had a right and duty to commandeer all of BP's resources (and much else). And of course the buck does not stop even there. We know that our gov't is devoted exclusively to protecting and enhancing the bottom lines of the big corporation. So who ultimately is at fault?

To even think about allowing deep water drilling to continue is totally criminal. For what? To extend the oil age for a few more years? At what price?

I would like to see some calculation of the total possible costs of the spill, the economic devastation throughout the affected states, the ecological devastation. (It can't all be captured by numbers, I know). It certainly far exceeds the market capitalization of BP, never mind the $37bn that they are projected to be responsible for.

Counting damage to the environment, our ONLY ultimate resource, and the cost of wars and their attendant devastation, and oil has already become very, very expensive, way beyond what we are paying for at the pump. Net energy calculations. dismal though they are, do not nearly suffice to show the madness afflicting us.

EDIT: Of course, the worst and most criminal thing was the complete betrayal of openness by the gov't. Instead of openness, fines and jail terms threatened against reporters and others. Only now a feint in the direction openness because of outcry.

I'd agree with you, Dave, but important decisions are never made by panels of scientists. Politicians jealously guard that realm for themselves. It would be nice if more politicians were scientifically literate - Secretary Chu is a too-rare example - but I've pretty much given up hope that that will happen.

Only now a feint in the direction openness because of outcry.--unquote

Probably more like desperation as fewer and fewer people believe a word the corp(se), the gov, dot mil, or the "mainstream" media says.

Finally, someone says it! Another mindbender--why can't Rep. Markey get his hands on a geological survey of the well area? Who is keeping that from him? The Administration? Why? Why should we all not be privy to that information? It's state and consequence belong to all of us. This is OUR world.

I would like to see some calculation of the total possible costs of the spill, the economic devastation throughout the affected states, the ecological devastation. (It can't all be captured by numbers, I know). It certainly far exceeds the market capitalization of BP, never mind the $37bn that they are projected to be responsible for. Counting damage to the environment, our ONLY ultimate resource, and the cost of wars and their attendant devastation, and oil has already become very, very expensive, way beyond what we are paying for at the pump. Net energy calculations. dismal though they are, do not nearly suffice to show the madness afflicting us.

The calculations have been done for a previous oil spill, Dave. At the library this morning, my fingers wandered past this last report that I am thumbing now. Funded by the Cousteau Society, Emergy analysis perspectives of the EVOS in PWS, AK (Brown, Woithe, Montague, Odum, & Odum, 1993). Some parallels can be drawn between oil extraction in AK and the GOM, although the human economies of the Gulf Coast are much larger. From the summary:

Emergy analysis of the EVOS and cleanup revealed that the cleanup costs exceeded the natural resource and direct economic losses incurred by between 110% and 740%, depending on the magnitude of the actual natural resource losses. In other words, the cleanup costs were 1.1 to 7.4 times more costly than the natural resource and economic damages that actually resulted from the spill….

…The pipeline's emergy flow is enormous in comparison to other aspects of the Alaskan system. The emergy value of the oil flow delayed during the 8 day pipeline shutdown following the Valdez spill was greater than the oil spill damage. If political oower follows in some degree from emergy, it is not likely that wildlife interests can prevent further oil drilling on the North Slope. It also follows that with such extreme emergy wealth involved, there is no reason why some of the wealth cannot be used to prevent environmental damage on the North Slope and insure continued emergy contributions of the tundra.

The value of total impact of the oil spill and associated events was between 3.3 and 4.8 billion macroeconomic dollars, 56% to 80% of which was in the cleanup effort. When expressed in emergy, the annual losses associated with the spill and cleanup represented: 1.1-1.3% of AK's emergy budget, 87-130% of the oil spill region's emergy budget and 330--490% of the budget of the PWS region.

Emergy benefit-cost ratios were calculated for 10 alternative methods of oil spill prevention. The benefits were calculated as the damage that would not be incurred should the method be implemented. The macroeconomic value required to implement each of the alternative prevention measures varied from 288 million to 8.8 billion macroeconomic dollars. Many measures proposed for prevention were found to divert more resources than would be saved (emergy required for prevention was greater than the losses prevented). Implementing these methods would result in a net loss. Double-hulled oil tankers were one of the alternatives found to be inappropriate. Three proposed measures for spill prevention did have positive net emergy benefits….

An emergy analysis was conducted for the process of transforming images of environmental damage of the oil spill into the shared memory in millions of people. Based on several assumptions, the emergy of the shared information about the spill was 3.4 times that of the spill phenomena. The pressure of the unified public opinion caused Exxon to invest up to 7.4 times more emergy into Alaska (in the form of cash payments) that was in the shared information. Thus a great amplification was achieved by the information system in going from the image of disaster to the response that resulted, possibly because of the high emergy of information already in people sensitized to environmental issues. The investment of emergy created a social storm phenomenon analogous to other systems in which energy is dumped rapidly into a small area. Other high emergy storms are the frenzied, autocatalytic energy storms of hurricanes, volcanic eruptions, great floods, and wars.

The great waste and secondary disaster produced by the television information system in the present state of American culture appears to be pathological. As a newly organizing system, global television may require trial and error before developing a pattern that contributes maximum emergy and the most prosperous sustainable economy. If confirmed with additional study, the emergy analysis of the system of environmental response by the television industry may suggest better means for finding appropriate responses.

Of course, the relative human economy value of the Gulf Coast is far larger, as is the damage, and so the idea that BP can outspend the massively negative public opinion in this case as Exxon did in the EVOS will probably not hold true. Is the current BP TV/media information storm similar to the EVOS? Are we seeing the same here at TOD?

Quote from an interesting article

"Despite an obvious suspect, oil, the answer is far from clear. The vast majority of the dead animals that have been found — 1,866 birds, 463 turtles, 59 dolphins and one sperm whale — show no visible signs of oil contamination. Much of the evidence in the turtle cases points, in fact, to shrimping or other commercial fishing, but other suspects include oil fumes, oiled food, the dispersants used to break up the oil or even disease."

A BP funded study will probable find they died from old age.

The funding won't be nearly so transparent.

Industry-associated 501 (c)(3) groups with green names and lofty mission statements will provide funding to other, even greener-seeming organizations that will, in turn, provide grants to university-based researchers.

With a little luck, the Sierra Club will name Corexit 9500 the Green Dispersant of the Year:

Before the oil rig exploded there were reports of outsized numbers of dead sea turtles showing up on Texas beaches, which might indicate something out of the norm was killing sea turtles prior to the oil spill.

It might.

It also seems possible (likely?) that fisherfolk, in a hurry to haul in as large a catch as they could during a Macondo-shortened season in not-yet-closed parts of the Gulf, "forgot" to open the turtle excluders in their nets, thereby drowning an unusually large number.

If either (or any) of these things were true, would that constitute substantive evidence of the safety or efficacy of dispersants?

No. It would not.

Is the fact that we do not know the cause of death for the extraordinarily-large numbers of dead turtles found this year evidence of anything, at all. No.

Is the fact that unusually large numbers of dead turtles (representatives of endangered species), along with numerous examples of other species of wildlife, have been discovered in the wake of the DWH blowout and gusher a very good reason to carefully and thoroughly investigate a possible link, and to proceed cautiously in deciding which remediation measures to attempt, and how to attempt them? You bet it is.

Should the very disturbing work cited by Iaato and a number of others here over the past few weeks be considered before we declare dispersants "safe" or the "lesser of evils" or our best available option? I don't see how there can be any doubt.

Since I am still on a roll, I would like to respond to the OP's discussion on toxicity. From what I can tell from this brief scan of the literature, there are many studies on efficacy, and few on toxicity. The primary evidence in the OP regarding toxicity is a NAP publication--some of you may have read elsewhere my concerns regarding the focus and biases of the National Academy of Science. The report was requested by MMS, NOAA, CG, and American Petroleum Institute. The report prioritized their analysis as follows:

Key components of an effective and integrated research effort should include efforts to further improve understanding of dispersant effectiveness and the potential impact of dispersed oil at meaningful scales to support decisionmaking in a broader array of spill scenarios, especially those scenarios where potential impacts on one portion of the ecosystem (e.g., water column) must be weighed against benefits associated with reducing potential impact on another (e.g., coastal wetland). In an effort to provide some prioritization, the following research recommendations are presented in order of significance. The most pressing or widely relevant issues are listed first, with less pressing or narrowly relevant issues raised later.

With the proposed USCG regulations requiring the availability of dispersants in pre-approval zones, the issue of availability will no longer be a limiting factor; thus the main questions to be addressed by responders in the pre-approval zones are: (1) Will mechanical recovery be effective and sufficient? (2) If not, is the oil dispersible? (3) If so, are the environmental conditions conducive to the successful application of dispersant and its effectiveness? and (4) If so, will the effective use of dispersants reduce the impacts of the spill to shoreline and water-surface resources without significantly increasing impacts to water-column and benthic resources? Better information is needed to determine the window of opportunity and percent effectiveness of dispersant application for different oil types and environmental conditions.

As far as I can tell the priorities of this report were again, focusing on efficacy rather than toxicity. The NAS' idea of "integrated research" is 1) lack of efficacy of mechanical means, 2) efficacy of dispersants, 3) environmental efficacy of applying dispersants, and 4) efficacy of dispersants (oh, yeah, maybe we should mention the critters, too).

The other study in the OP was an EPA study published June 30, 2010. Methods: The LC50 is defined as the concentration of a substance causing mortality in 50% of test organisms for a specified time interval, in this case, 48-hours for the mysid test and 96-hours for the silverside test. That's it. No mention of longer periods of exposure, no mention of comparison with a control, either sea water or oil/seawater mix. Just a popularity contest for larvae dipped briefly in dispersants and then rinsed? Could there be a methodology more partial to industry?

Fuller et al. (2004) I couldn't access full text. The abstract claims to look at toxicity in declining and continuous exposure of unknown periods of time. Why aren't there specific methods and stats in the abstract? And the last sentence concluding the abstract is very strong language for a weakly designed study such as this one. I would love to see the methods, stats, and the acknowledgements on this study.

The data suggested that oil media prepared with a chemical dispersant was equal to or less toxic than the oil-only test medium. Data also indicated that continuous exposures to the test media were generally more toxic than declining exposures. The toxicity of unweathered crude oil with and without dispersant was also evaluated using Menidia beryllina under declining exposure conditions. Unweathered oil-only media were dominated by soluble hydrocarbon fractions and found to be more toxic than weathered oil-only media in which colloidal oil fractions dominated. Total concentrations of petroleum hydrocarbons in oil-plus-dispersant media prepared with weathered and unweathered crude oil were both dominated by colloidal oil and showed no significant difference in toxicity. Analysis of the toxicity data suggests that the observed toxicity was a function of the soluble crude oil components and not the colloidal oil.

Doesn't anybody read the fine print anymore? Or are we just suckers for headlines?

Hey, Iaato: If you'll send me your email address I'll send you a pdf of the Fuller article, so you can see the details. humphrey at ufl dot edu

I don't think that number of dead animals is worth the trouble for BP to lie. It'll be a really good PR coup for them if they agree to the number, and commit to put in hatcheries or otherwise help the animal population grow to replace the victims. Think about it, how much does it cost to get one sperm whale, 463 turtles, 59 dolphins and 1866 birds? It's peanuts, those drilling rigs they're using cost $500,000 per day, and they got several working to control the well.

They already committed to give the money they make from capturing the oil to a wildlife fund. That's at least $1 million a day. So there's going to be some happy turtle growers and pelican breeders getting funded by the BP oil spill cash flow.

"...happy turtle growers..."

I don't even know where to start. OK, here: Before the Macondo gusher, there were, perhaps, 1,000 sexually mature female Kemp's Ridleys on Earth. That's quite a bit better than the 200 that were counted in the mid 80's, but it follows decades of extremely difficult work and they are still the most endangered turtles on the planet.

Ask these people:

" much does it cost to get one sperm whale..."

One? Oh... since they are only "vulnerable," BP might even be able to "afford" a few. Of course, what they'd do with them is somewhat problematic. I don't think anyone has perfected captive breeding for the world's largest toothed animals, just yet.

In case you're interested in learning why threatening the habitat and food supply of sperm whales may be problematic, Google for the selective hunting of large males and then check out the reproductive strategy known as K selection.

Re GOM sperm whales, see also my post of core info:

Thanks. I remembered the post, but didn't find it. The Google/Drupal search facility...

As a learning newbie (around a month or more), I read lots of comments I disagree with, and out of humility, don't comment back. But yours is just beyond my comprehension. The turtle growers are going to benefit from this?

And where exactly are the turtles going to go to live?

The lack of respect for life itself around (by a few here) is truly astounding. We need our eco-systems to produce things we can eat and harvest. We will never be able to eat oil, coal, natural gas, gold, minerals, uranium, or anything else of high value that our developed societies seem to think more important to exploit right now, rather than think long-term (seven generations was the rule for Native Americans before we arrived).

Right now it appears that global corporations, with the support of their stock holders, are on an ruthless crusade to exploit any and every natural resource left, as fast as they can, because they know it's all going to come to an end in a rather short time frame. Every effort by long-term thinking people is being thwarted by the billion dollar budgets of these corporations to buy out politicians, while buying millions of dollars worth of media slots to show us how good they are for the planet (i.e. BP - Beyond Petroleum).

Your comment encapsulates the essence of that attitude. I hope that something in your life happens that will allow you to re-evaluate some basic concepts. We cannot live quality lives in destroyed environments. Nature is a gift to all of us, providing us with all we need, if we use it wisely. Greed and cruelty, be they material, mental, or physical, work against life itself - always.

I wish you well, but I had to gag when I read what you wrote.

"...happy turtle growers and pelican breeders..."

Wow. Just, wow. Talk about an uninformed opinion.

Sea turtles in general aren't "grown" or bred in captivity, not in any significant numbers anyway. The only groups that are associated with them try and care for the sick and injured ones and return them to their native habitat; perhaps they will benefit from BP's largesse but I'm sure they'd rather not have to in the first place. There has been an emergency program to relocate turtle eggs from Gulf beaches to the Atlantic, but everyone admits this is an extreme measure and there's a lot of concern about survival rates. Kemp's Ridley sea turtles, for example, nest on Mexican and Texan beaches, but their young head for the northern Gulf to feed after hatching, right where (you guessed it!) the oil is located. If there's no food for them to eat when they get there, we've just lost a generation of an endangered species, a possible fatal blow to them.

Ecotoxicol Environ Saf. 2004 Nov;59(3):300-8.
Oil dispersant increases PAH uptake by fish exposed to crude oil.

Ramachandran SD, Hodson PV, Khan CW, Lee K.

School of Environmental Studies, Queen's University, Kingston, Ont., Canada K7L 3N6.

The use of oil dispersants is a controversial countermeasure in the effort to minimize the impact of oil spills. The risk of ecological effects will depend on whether oil dispersion increases or decreases the exposure of aquatic species to the toxic components of oil. To evaluate whether fish would be exposed to more polycyclic aromatic hydrocarbon (PAH) in dispersed oil relative to equivalent amounts of the water-accommodated fraction (WAF), measurements were made of CYP1A induction in trout exposed to the dispersant (Corexit 9500), WAFs, and the chemically enhanced WAF (dispersant; CEWAF) of three crude oils. The crude oils comprised the higher viscosity Mesa and Terra Nova and the less viscous Scotian Light. Total petroleum hydrocarbon and PAH concentrations in the test media were determined to relate the observed CYP1A induction in trout to dissolved fractions of the crude oil. CYP1A induction was 6- to 1100-fold higher in CEWAF treatments than in WAF treatments, with Terra Nova having the greatest increase, followed by Mesa and Scotian Light. Mesa had the highest induction potential with the lowest EC50 values for both WAF and CEWAF. The dispersant Corexit was not an inducer and it did not appear to affect the permeability of the gill surface to known inducers such as beta-napthoflavone. These experiments suggest that the use of oil dispersants will increase the exposure of fish to hydrocarbons in crude oil.

PMID: 15388269 [PubMed - indexed for MEDLINE]

Emphasis added.

The problem with these studies is that they don't present a realistic picture of what is happening in the Gulf. In the Gulf we have oil consuming microorganisms eating the oil in conjunction with the fish being present in the system. These micro-organisms reduce the level of hydrocarbons in the system, potentially reducing the exposure of the fish.

This study completely ignores that process.

In addition the dispersal of the oil prevents it from reaching the surface where there is a lot more life than in the lower ocean. This life isn't exposed to the dispersed oil at all. And then should the oil get into the marshes things get even worse.

So while these reports are interesting it is pretty easy to anticipate the results, and they really don't give much insight as to whether or not the use of surfactant is actually harmful or beneficial.

Experts seem to have a range for the amount of the oil on or near the surface but I don't think any have said that surface life won't be exposed to the dispersed oil at all.

Also, don't forget that dispersants have been applied onto the sea surface by vessels and aircraft.

STA: In the Gulf we have oil consuming microorganisms eating the oil in conjunction with the fish being present in the system. These micro-organisms reduce the level of hydrocarbons in the system, potentially reducing the exposure of the fish.

And potentially reducing TDO concentrations to problematic levels, et cetera.

I'm only making the points I'm making...

While there is nothing on dispersant effects on humans in Pubmed (yet), there are many anecdotal reports of hydrocarbon pneumonias, neurotoxicity, and chemical sensitivity due to the spill. We've never had a massive exposure to humans such as this. Just be patient, Speaker. These things take time. And most of the lab tests do not reflect the complexity of the water column and ecosystems.

I tried searching for dispersant toxicity with Cuil insead of Google, and got a different perspective.

An estimated 25,000 birds died as a result of the Torrey Canyon spill because
the incident coincided with their northerly migration. The coasts of southern
England and Brittany are nesting beaches for a variety of seabirds such as
guillemots, razorbills, shags, puffins, and Great Northern divers. Thousands of
oiled birds were picked up from the beaches for treatment, but the survival rate
was only around one percent due to ingestion of oil, pneumonia, and improper
handling and cleaning.

The Torrey Canyon incident was the first incident to draw universal attention
to the dangers of dispersants. Extremely large quantities of dispersants were
used during the response, clearly for aesthetic and not ecological purposes.
Contamination by oil without dispersants resulted in less adverse biological
effect than where dispersants were used. Many herbivores, mainly limpets, and
some barnacles were killed due to the toxicity of the dispersant. Widespread
mortalities on the West Cornish coast set the stage for a large-scale experiment
on the development of a mature community, normally found on rocky shores, and
the influence of herbivores and predators on the ecosystem. However, the
resultant statistical comparisons may be somewhat inaccurate due to the small
amount of pre-spill data, the lack of control sites where the oil was left
totally untreated, and uncertainties of how much dispersant reached marginal
areas. Early estimates indicated rapid recovery of species along the beach,
while long term studies revealed extremely slow recovery. Wave-beaten rocky
areas that received only light oiling took approximately 5-8 years to return to
normal while areas receiving heavy and repeated dispersant applications took
9-10 years to recover. A 1978 study showed that a rare hermit crab species had
not re-appeared in the spill area.

The link below shows a list of current research from one company. Please note the sponsors listed for each study--very instructive. This is big business.

May 4, 2006The board of directors of the Prince William Sound Regional Citizens’ Advisory Council this week voted to oppose any use of chemical dispersants for responding to North Slope crude oil spills in Prince William Sound and other areas affected by the Exxon Valdez oil spill of 1989.

The action came May 3 in Valdez at a regular meeting of the board and was taken at the recommendation of its Scientific Advisory Committee and a project team set up to examine the issue.

Previously, the council position was that dispersants could be used on an oil spill as a last resort if mechanical recovery efforts with booms and skimmers proved ineffective.

With this week’s action, the council is now on record as opposing dispersant use in the Exxon oil-spill region under any circumstances.

In theory, chemical dispersants do as their name implies: they disperse surface oil into the water column, thereby diluting it, preventing it from fouling shorelines, and speeding up the process by which bacterial action renders it harmless.

But, the council concluded, years of research have failed to bear out the claims of dispersant proponents.

“Until such time as chemical dispersant effectiveness is demonstrated in our region and shown to minimize adverse effects on the environment, the council does not support dispersant use as an oil spill response option,” the new position states.

“This puts the responsibility back where it belongs,” said Connie Stephens, a board member from Valdez. “Until you can prove to me it works, I don’t want it in there.”

The ban comes after the council has spent years observing dispersant trials, reviewing dispersant research, and sponsoring independent research of its own. Most recently, the council commissioned a report called “Stability and Resurfacing of Dispersed Oil,” by Dr. Merv Fingas, a Canadian scientist and world-renowned authority on dispersants.

Dispersants require a considerable level of wave activity in order to work. Resurfacing refers to the fact that, if the waves subside, the oil may un-disperse and return to the surface in an oil-dispersant mixture that may be even harder to clean up than untreated oil.

After reviewing and analyzing the Fingas report, the council’s science committee concluded that resurfacing “has not been well-defined or studied. A common argument for the use of chemical dispersants is to keep oil off of environmentally sensitive areas. However, due to the potential of resurfacing, impacts cannot be so well defined. Oil may simply resurface and impact another environmentally sensitive area.”

From Google Scholar, Native impacts of the cleanup of EVOS:

And an honest man in Nigeria? Did he type this piece with a wry smile on his face?
The author is grateful to Shell Petroleum Development Company, Nigeria for providing crude oil and Dr L.O. Chukwu for providing the dispersant used for the study.

Edit to add, 7/16, something Tin Foil posted in the open thread, that really makes the chills run up my spine. We know this happens on the small scale already, and it illustrated my points about the current state of science in general and the NAS. But this is creepy; all-out highjacking on a large scale. If you haven't watched the documentary, The Corporation, I recommend it highly.

BP PLC attempted to hire the entire marine sciences department at one Alabama university, according to scientists involved in discussions with the company's lawyers. The university declined because of confidentiality restrictions that the company sought on any research. The Press-Register obtained a copy of a contract offered to scientists by BP. It prohibits the scientists from publishing their research, sharing it with other scientists or speaking about the data that they collect for at least the next three years....

Robert Wiygul, an Ocean Springs lawyer who specializes in environmental law, said that he sees ethical questions regarding the use of publicly owned laboratories and research vessels to conduct confidential work on behalf of a private company. Also, university officials who spoke with the newspaper expressed concern about the potential loss of federal research money tied to professors working for BP.

With its payments, BP buys more than the scientists' services, according to Wiygul. It also buys silence, he said, thanks to confidentiality clauses in the contracts. "It makes me feel like they were more interested in making sure we couldn't testify against them than in having us testify for them," said George Crozier, head of the Dauphin Island Sea Lab, who was approached by BP. "It makes me feel like they were more interested in making sure we couldn't testify against them than in having us testify for them," said George Crozier, head of the Dauphin Island Sea Lab, who was approached by BP....


Environ Pollut. 2009 Mar;157(3):1058-61. Epub 2008 Nov 22.
Preliminary investigation of the effects of dispersed Prudhoe Bay Crude Oil on developing topsmelt embryos, Atherinops affinis.

Anderson BS, Arenella-Parkerson D, Phillips BM, Tjeerdema RS, Crane D.

Department of Environmental Toxicology, University of California, Davis, CA 95616-8588, USA.

Static exposure experiments were conducted to assess the toxicity of dispersed Prudhoe Bay Crude Oil (PBCO) to embryos of the topsmelt (Atherinops affinis). Treatment with the dispersant COREXIT 9500 resulted in greater hydrocarbon concentrations in chemically enhanced water-accommodated fractions (CEWAFs) of oil, relative to the untreated water-accommodated fractions (WAFs). Topsmelt embryo development and survival to hatching was significantly inhibited in CEWAF tests while minimal effects on embryo-larval survival were observed in WAF tests. Increased hydrocarbon concentrations in the CEWAF tests caused cardiovascular and other abnormalities in developing topsmelt embryos.

PMID: 19028002 [PubMed - indexed for MEDLINE]

Emphasis added.

Just a few more and then I'll stop, for now.

Please, defenders of dispersants, note that I am not making any claim other than these:

1. It has not been clearly established that CEWAF is less harmful to organisms in the marine environment than WAF.

2. It has not been clearly established that the deepwater application of dispersants has any particular effects at all in a real-world scenario, much less that whatever effects such application may have are, overall, beneficial.

3. It has not even been established that the surface application of dispersants 40 miles offshore has any particular effect(s) on the amount of oil reaching sensitive shoreline environments, or that dispersed oil that does reach shore is any less harmful to the environment that WAF alone.

Comp Biochem Physiol C Toxicol Pharmacol. 2009 Aug;150(2):218-23. Epub 2009 May 3.
Biochemical changes in rockfish, Sebastes schlegeli, exposed to dispersed crude oil.

Jung JH, Yim UH, Han GM, Shim WJ.

Oil and POPs Research Group, KORDI, Geoje-shi, 656-834, Republic of Korea.

This paper describes the response of the ovoviviparous rockfish, Sebastes schlegeli, to hydrocarbons in the water-accommodated fraction (WAF) of crude oil, in the presence or absence of oil dispersants. Concentrations of cytochrome P-450 1A (CYP1A) and levels of its catalytic activity ethoxyresorufin O-de-ethylase (EROD) in rockfish exposed to WAF at concentrations of 0.1% and 1% were significantly increased by the addition of a dispersant, Corexit 9500 after 48 h exposure. After 72 h exposure, the levels of CYP1A and EROD activity were significantly increased in 0.1% and 0.01% chemically enhanced WAF (CEWAF) (Corexit 9500 and Hiclean II dispersant). Bile samples from fish exposed to WAF alone had low concentrations of hydrocarbon metabolites, exemplified by 1-hydroxypyrene. After 72 h exposure, hydrocarbon metabolites in bile from fish exposed to WAF in the presence of either Corexit 9500 or Hiclean II were significantly higher compared with fish exposed to WAF alone or control fish. These experiments confirm that the use of oil dispersants will increase the exposure of ovoviviparous fish to hydrocarbons in oil.

PMID: 19410657 [PubMed - indexed for MEDLINE]

Emphasis added.

Environ Toxicol Chem. 2005 Jun;24(6):1496-504.
Effect of dispersant on the composition of the water-accommodated fraction of crude oil and its toxicity to larval marine fish.

Couillard CM, Lee K, Légaré B, King TL.

Environmental Sciences Branch, Department of Fisheries and Oceans, Maurice Lamontagne Institute, P.O. Box 1000, Mont-Joli, Quebec G5H 3Z4, Canada.

Newly hatched mummichog (Fundulus heteroclitus) were exposed in a 96-h static renewal assay to water-accommodated fractions of dispersed crude oil (DWAF) or crude oil (WAF) to evaluate if the dispersant-induced changes in aqueous concentrations of polycyclic aromatic hydrocarbons (PAH) affected larval survival, body length, or ethoxyresorufin-O-deethylase (EROD) activity. Weathered Mesa light crude oil (0.05-1 g/L) and filtered seawater with or without the addition of Corexit 9500 were used to prepare DWAF and WAE At 0.2 g/L, the addition of dispersant caused a two- and fivefold increase in the concentrations of total PAH (sigmaPAH) and high-molecular-weight PAH (HMWPAH) with three or more benzene rings. Highest mortality rates (89%) were observed in larvae exposed to DWAF (0.5 g/L; sigmaPAH, 479 ng/ml). A reduction in body length was correlated with increased levels of sigmaPAH (r2 = 0.65, p = 0.02) and not with HMWPAH. The EROD activity increased linearly with HMWPAH (r2 = 0.99, p = 0.001) and not with sigmaPAH. Thus, chemical dispersion increased both the sigmaPAH concentrations and the proportion of HMWPAH in WAF. Dispersed HMWPAH were bioavailable, as indicated by a significantly increased EROD activity in exposed mummichog larvae, and this may represent a significant hazard for larval fish.

PMID: 16117127 [PubMed - indexed for MEDLINE]

Emphasis added.

Last one.

STA: You're correct that these studies were conducted in environments bearing little resemblance to the real-world situation in the Gulf today, and that no reliable conclusions can be drawn.

However, that is true of all studies relevant to these issues but, for some reason, many of you seem to be confident that "the science" supports your conclusions about the safety and efficacy of dispersant application to the oil from the Macondo gusher. I don't think that's reasonable.

Environ Pollut. 1988;55(3):221-38.
Evaluation of alternative oil spill cleanup techniques in a Spartina alterniflora salt marsh.

Kiesling RW, Alexander SK, Webb JW.

Department of Marine Biology, Texas A&M University at Galveston, Galveston, Texas 77553-1675, USA.

Three oil spill situations which cause long-term impact were simulated in 1 m(2) salt marsh plots to evaluate the effectiveness of alternative cleanup techniques at removing oil and reducing damage to Spartina alterniflora. Cleanup techniques, implemented 18-24 h after oiling, were not effective at removing oil after sediment penetration. When oil remained on the sediment surface, flushing techniques were most effective at removal, reducing levels of added oil by 73% to 83%. The addition of dispersant to the flushing stream only slightly enhanced oil removal. Clipping of vegetation followed by sorbent pad application to sediment was moderately effective, reducing added oil by 36% to 44%. In contrast to flushing and clipping, burning increased the amount of oil in sediment by 27% to 72%. Although flushing and clipping were effective at oil removal, neither technique reduced initial damage to plants or enhanced long-term recovery. While flushed plots sustained no additional plant damage due to cleanup, clipped and burned plots sustained additional initial plant damage. Based on these results, first considerations should be given to natural tidal flushing as the means to remove oil, especially in salt marshes subject to ample tidal inundation. Although our results do not support cleanup in salt marshes with ample tidal inundation, low pressure flushing may be warranted when fuel oils or large quantities of crude oil impact salt marshes subject to reduced tidal flushing. Flushing, when warranted, should be initiated prior to oil penetration into the substrate. Clipping may be considered as a cleanup response only when heavy oil cannot be effectively removed from vegetation by flushing. Burning is not recommended because it enhances oil penetration into sediment and causes substantial initial plant damage.

PMID: 15092503 [PubMed]

Emphasis added.

Indigo Girls

Galileo's head was on the block
the crime was looking up for truth
and as the bombshells of my daily fears explode
I try to trace them to my youth

And then you had to bring up reincarnation
over a couple of beers the other night
and now I'm serving time for mistakes
made by another in another lifetime

How long till my soul gets it right
can any human being ever reach that kind of light
I call on the resting soul of galileo
king of night vision, king of insight

And then I think about my fear of motion
which I never could explain
some other fool across the ocean years ago
must have crashed his little airplane

How long till my soul gets it right
can any human being ever reach that kind of light
I call on the resting soul of galileo
king of night vision, king of insight

I'm not making a joke, you know me
I take everything so seriously
if we wait for the time till all souls get it right
then at least I know there'll be no nuclear annihilation
in my lifetime I'm still not right

I offer thanks to those before me
that's all I've got to say
'cause maybe you squandered big bucks in your lifetime
now I have to pay
but then again it feels like some sort of inspiration
to let the next life off the hook
but she'll say "look what I had to overcome from my last life
I think I'll write a book"

How long till my soul gets it right
can any human being ever reach the highest light
except for Galileo God rest his soul
(except for the resting soul of Galileo)
king of night vision, king of insight

How long
(till my soul gets it right)
[til we reach the highest light]
how long
(till my soul gets it right)
[til we reach the highest light]
how long (Merchants of Doubt)

Waiting On The World To Change
John Mayer

Me and all my friends
We're all misunderstood
They say we stand for nothing and
There's no way we ever could

Now we see everything that's going wrong
With the world and those who lead it
We just feel like we don't have the means
To rise above and beat it

So we keep waiting
Waiting on the world to change
We keep on waiting
Waiting on the world to change

It's hard to beat the system
When we're standing at a distance
So we keep waiting
Waiting on the world to change

Now if we had the power
To bring our neighbors home from war
They would have never missed a Christmas
No more ribbons on their door
And when you trust your television
What you get is what you got
Cause when they own the information, oh
They can bend it all they want

That's why we're waiting
Waiting on the world to change
We keep on waiting
Waiting on the world to change

It's not that we don't care,
We just know that the fight ain't fair
So we keep on waiting
Waiting on the world to change

And we're still waiting
Waiting on the world to change
We keep on waiting waiting on the world to change
One day our generation
Is gonna rule the population
So we keep on waiting
Waiting on the world to change

We keep on waiting
Waiting on the world to change

Why Power is not a Dirty Word

Hey all, just a geologist, so could someone with the relevant knowledge respond why Corexit was chosen over Dispersit? Granted, my comprehension of chemistry is limited, and biology probably even less, but the toxicology of Dispersit appears to be much less detrimental than that of the dispersant being used...

What gives? Was it logistical?

EDIT: for clarity

Sol: Actually the opposite is the case. The LC50 measure is the Lethal Concentration at which 50% of the animals in an exposed sample die. So half the animals died when exposed to ~12 parts per million of Dispersit, whereas half the animals died when exposed to ~42 parts per million of Corexit. So Dispersit has a lower LC50 and a higher toxicity. (This is the confusion of terms that was mentioned in the BP letter.)

Note, however, that the toxicologists consider this difference to be not very substantial, so they classified both as "slightly toxic." The narrative term also reflects the degree of toxicity relative to other things to which animals are exposed in the environment.

This similarity is easy to doubt based simply on the numbers, but it's important IMO to recognize that these are toxicology specialists who are using their professional judgment to communicate to others who, while quite interested, are joining the discussion without much perspective. Some will be cynical about that, but I respect it and have to have really good reasons to judge otherwise. (The same goes for professionals working in any complex field where one's own knowledge/experience is limited.)

Thanks for the key post and the simple clarification above. Just a tad more narrative might have shed a lot of light on your blocks of graphs, a couple of the axis just didn't come into focus (mentally for me) even after I expanded them to a more readable size.

I really do have my doubts that we will have a good handle on the tradeoffs involved here even after the studies are in. We see the shore. The water column is mostly invisible to us but it is so huge in so many ways.

Thanks to kalliergo for the last few posts, starting down the trail of exploring the toxicology of oil and dispersants. This is helpful, and it shows how complex this is, how little we know, and especially how little we know about what we really need to know to decide what to do.

At the end of the day, a responsible person has to do more than simply show that use of a management practice is bad because it has some bad effects. One also has to decide whether the alternatives are worse. If you can't evaluate the tradeoffs and make the best decision under the circumstances, you're fired.

Now, here's a new opportunity to learn more about the toxicology question. Dr. Riki Ott, a marine toxicologist who has written two books on the Exxon Valdez oil spill, will be giving public lectures in Tallahassee FL on 21-Jul and 22-Jul, Crawfordville FL on 23-Jul, and Apalachicola FL on 24-Jul. For details, you can contact her here: complex this is, how little we know, and especially how little we know about what we really need to know to decide what to do.

Yes. We wouldn't be having discussions and disagreements like this, in the midst of a possible eco-disaster, if we as a society had done our homework in a timely manner, and if the people we entrusted with ensuring that our offshore exploration and production is as safe as reasonably achievable had done their jobs.

Let's try to get it right, moving forward.

One also has to decide whether the alternatives are worse.

Yes. Of course, that imperative is bidirectional. Our "when in doubt, do something" bias, all too often, leads us into a world of unintended consequences. In the case under discussion, I think that is at least as great a danger as the more restrained alternative.

OTOH, our (collective) piss-poor prior planning has left us with a paucity of good choices.

If you can't evaluate the tradeoffs and make the best decision under the circumstances, you're fired.

Sometimes. Often not until after we all suffer the consequences.

Thanks for the Riki Ott heads-up.

Generally speaking, discussions of dispersant toxicity -- e.g.. test reports by the EPA -- are dangerously misleading.
The dispersant does not need to be toxic at all to activate (or develop) the toxic effects of the crude oil itself.
When a dispersant is applied onto an oil slick in deep water, the effect is to disperse oil that until that time was of limited toxicity and had limited impact on wild life. Before that, it was a simple matter to collect the oil with skimmers, the only reasonable method in deep water. After this application, however, the oil can no longer be collected. The dispersant acts as a surfactant (detergent) and emulsifies the more volatile compounds in the oil. These are then essentially irreversibly dissolved in the water, fully developing the toxicity of the oil itself.
The less-volatile compounds such as tars settle to the bottom or agglomerate and develop their impact on mullusks, crustaceans and fish living deeper down. Once a certain level is reached, these living things can no longer be used as food. The time it takes the oil-eating bacteria to degrade these components will vary, but the process can take years. Vast areas of the Gulf can be effectively lost to fishing for a very long time.
That the EPA would even think of perpetrating this disastrous -- and completely unnecessary -- toxification process is beyond me.
Sure, in the shallows, dispersants can and should be used. But in deep water, there is absolutely no excuse for it.
I have contacted the EPA with these concerns and at this time, the EPA appears oblivous to any of the concepts I have laid out here. The only hope we have is that some foreign government or entity will bring this to the attention of the world press at some point and initiate an action forcing our government to take the appropriage steps. Dispersant use MUST be banned in deep water whenever skimmers are available.

Из худого кармана и последний грош валится.