Does dispersant toxicity count? No toxicity standard limits EPA’s listing of oil spill dispersants

Richard Denison, Ph.D., is a Senior Scientist.  EDF’s Health Program Intern Shannon O’Shea provided valuable assistance in the research for this post.

The more I have looked into the question of how dispersants get listed and selected under the country’s National Oil and Hazardous Substances Pollution Contingency Plan (NCP), the more disturbing it gets.

It turns out EPA regulations impose no maximum toxicity limits on dispersants allowed to be listed on the NCP Product Schedule.  Nor is such a listing deemed by EPA to be an approval or authorization for use of a dispersant on a spill – it merely signifies (with one exception) that required data have been submitted to EPA.  Yet, once listed, a dispersant is effectively “pre-authorized” for use, and the guidance provided to officials charged with deciding whether to allow use of a dispersant, and if so which one and in what quantities and settings, makes scant mention of toxicity as a factor to be considered in the selection decision.

No wonder there’s little incentive to do the research needed to understand the full scope of impacts associated with dispersant use, let alone to develop and shift to safer and more effective dispersants.

This post examines the following questions:

  • How does a dispersant get listed on the NCP Product Schedule?
  • Is listing of a dispersant considered approval for use on a spill?
  • How is a dispersant approved for use in a spill?
  • How are decisions made about dispersant use?
  • How is toxicity information considered in making decisions about dispersant use?

How does a dispersant get listed on the NCP Product Schedule?

Two types of laboratory tests are required of dispersants:

  • effectiveness, and
  • acute aquatic toxicity (two tests, one on shrimp, the other on fish)

For details, see Section 300.915 of Subpart J of the NCP, which covers the use of dispersants.

For a dispersant to get listed, the test data must be submitted to EPA, which reviews it:

That’s it.

No standard applies to toxicity; that is, there is no specified level of toxicity above which a dispersant is ineligible for listing. 

EPA’s website on dispersants has the following Q&A, which notes the requirement to do toxicity tests but not to meet any toxicity standard:

Q:  Does EPA make a determination on the toxicity of dispersants before they are approved?

A:  EPA requires toxicology tests and reports for all dispersants that are approved on the National Contingency Plan (NCP) Product Schedule, the authorized list of dispersants. All determinations regarding the specific application or use of a dispersant are made by the Federal On-Scene Coordinator in charge of the response.

We further confirmed the lack of any toxicity standard via a call to the NCP Product Schedule Information Line on June 11.

So any consideration of the acceptable level of toxicity is not done by EPA, but rather by the FOSC.

The current EPA leadership appears to squarely acknowledge that the lack of a toxicity standard is a shortcoming in the NCP and EPA regulatory authority.  On May 27, EPA Administrator Jackson gave testimony before a subcommittee of the House Energy and Commerce Committee that addressed the issue of dispersant toxicity:

Mr. Chairman, we are in a position with no perfect solution. As we emerge from this response, I commit to revisiting the regulations surrounding EPA’s response, particularly regarding dispersant registration under the National Contingency Plan. I also commit to sharing the results with this committee and working with you to tighten the underlying laws, as necessary.

Is listing of a dispersant considered approval for use on a spill?

Despite frequent references on the dispersants page of EPA’s website to dispersants on the Product Schedule being “authorized” for use, elsewhere EPA makes clear that listing is not in fact authorization for use on a spill.  Indeed, EPA regulations even specify a disclaimer that dispersant makers are to use to dispel that notion:

Disclaimer Information

The listing of a product on the NCP Product Schedule does not constitute approval of the product. To avoid possible misinterpretation or misrepresentation, any label, advertisement, or technical literature that refers to the placement of the product on the NCP Product Schedule must either reproduce in its entirety EPA’s written statement that it will add the product to the NCP Product Schedule under Sec. 300.920(a)(2) or (b)(2), or include the disclaimer shown below. If the disclaimer is used, it must be conspicuous and must be fully reproduced. Failure to comply with these restrictions or any other improper attempt to demonstrate the approval of the product by any National Response Team (NRT) or other U.S. Government agency shall constitute grounds for removing the product from the NCP Product Schedule. [40 CFR 300.920(e)]


[PRODUCT NAME] is on the U.S. Environmental Protection Agency’s NCP Product Schedule. This listing does NOT mean that EPA approves, recommends, licenses, certifies, or authorizes the use of [PRODUCT NAME] on an oil discharge. This listing means only that data have been submitted to EPA as required by subpart J of the National Contingency Plan, Sec. 300.915. 


How, then, is a dispersant approved for use in a spill?

Administrator Jackson was asked about that in the same House hearing I referred to earlier:

They [BP’s proposed use of Corexit® dispersants at Deepwater Horizon] were approved, pre‐approved through the Federal on‐scene coordinator’s [FOSC] regional response plan that use of dispersants at the surface, as long as it was on the EPA product schedule, was allowable for surface applications. So that is yes. I believe you said, were they approved?  Yes, throughout the ‐‐ by the FOSC ultimately, but in conjunction with the RRT [Regional Response Team].

The FOSC for the Deepwater Horizon spill is now Rear Admiral James Watson of the U.S. Coast Guard, who recently replaced Rear Admiral Mary Landry, who returned to Gulf hurricane readiness duty (we can only pray that their paths don’t cross again this hurricane season!).

How are decisions made about dispersant use?

As noted before, EPA does not use the toxicity data to determine whether or not to list a dispersant on the Product Schedule.  Rather, as noted in EPA’s factsheet on the Product Schedule:

Q:  How does EPA decide whether to list a product?

A:  EPA’s NCP Product Schedule Manger [sic] conducts a review of the product data to confirm that the required information is complete and valid.  The data requirements are designed to provide sufficient information to Federal On-Scene Coordinators (FOSCs) and Regional Response Teams (RRTs) to determine whether, and in what quantities, a product may be used to control an oil discharge. (emphasis added)

I have found little information on government websites about how decisions are being made on dispersant choice and scale of use in the Deepwater Horizon incident.  EPA has indicated that the Coast Guard is in charge of such decisions.

As I discussed in an earlier post, a joint Directive from EPA and the Coast Guard issued on May 26 called on BP to significantly reduce dispersant use and to “eliminate the surface application of dispersants.”  However, it did provide that “in rare cases where there may have to be an exemption,” BP is to request and justify an exemption in writing, and the exemption shall be provided “only as specifically approved in writing by the USCG Federal On‐Scene Coordinator (FOSC).”

As I noted in that earlier post, surface application of dispersants has continued on virtually a daily basis since the Directive was issued (up to and including yesterday), albeit at volumes that are averaging about half of the pre-Directive average.

I have inquiries in to, but don’t yet have a response from, the Coast Guard, seeking more information about this continued use and requesting copies of the written exemption requests and approvals granted to BP by the FOSC.

How is toxicity information considered in making decisions about dispersant use?

So, under the status quo, what happens to the information on toxicity developed by dispersant makers and provided on the Product Schedule?

I have also found little information on whether, and if so how, toxicity information is to be explicitly considered in making decisions on dispersant choice and scale of use, whether in the Deepwater Horizon incident or more generally.

The National Oceanic and Atmospheric Administration (NOAA) plays a role in this and other spills in shaping both response and restoration activities.  Its website provides several guidance documents for responders that address the question of selection and use of materials and technologies for responding to a spill.  The most comprehensive one appears to be NOAA’s “Selection Guide for Oil Spill Applied Technologies,” dated January 2003.

The document has a FAQ specifically on the selection of products listed on the NCP Product Schedule.  The FAQ has these two interesting statements:

Being listed on the National Product Schedule does NOT mean that the product is recommended or endorsed by the USEPA for use on an oil spill.


[B]eing listed on the Product Schedule does not mean that the products have been proven effective or are considered non-toxic. In fact, listed products may be highly toxic to native plants and animals.

The document has a section to guide responders in dispersant selection.  It has no mention of toxicity at all.  Below is the entirety of that section’s health and environmental guidance for dispersants:

Health and Safety Concerns

  • Ensure that dispersants are not applied in areas where on-scene personnel could be sprayed or affected by overspray.
  • Deploy monitoring crews in vessels only under safe sea conditions.

Limiting Factors/Environmental Constraints

  • Effectiveness decreases with heavy, weathered, and emulsified oils.
  • Effectiveness of current formulations decreases significantly with decreasing salinity; essentially, there is no effective freshwater dispersant.
  • Most become ineffective when the viscosity reaches 20,000 cP. Corexit 9500 may be effective on oils with a viscosity up to 40,000 cP, extending the “window of opportunity” for dispersant application.
  • Most pre-approvals specify a minimum water depth (usually 30 feet), distance from shore, or a specific, sensitive resource such as coral reefs, and maximum time after release. Other constraints include separation distance from rafting birds and avoidance of spraying over marine mammals and sea turtles.
  • Not likely to be 100% effective; often requires mechanical recovery and/or shoreline cleanup.

Monitoring Requirements/Suggestions

  • Follow the Special Monitoring of Applied Response Technologies (SMART), which consists of a hierarchy of activities:
    • visual aerial observations by trained observers;
    • fluorometry sampling of the dispersed plume, tracked by drifters; and
    • water sampling to validate the quantitative fluorescence values and characterize the composition of the dispersed oil.
    • Monitoring should not be a prerequisite for dispersant approval in any specific incident.

Waste Generation and Disposal Issues

  • Effective use of dispersants should significantly reduce the amount of oily wastes generated.

Interestingly, the main references cited are reports on dispersant use from the American Petroleum Institute and Exxon USA.

There is a 22-page Appendix (E) titled “Understanding Toxicity, Exposure, and Effects Related to Spill Response Countermeasures.”  This appendix for the first time makes explicit mention of toxicity, and provides a basic primer on toxicity, exposure and adverse effects.  It is focused mainly on the toxicity of the oil itself.  It notes the need, but provides no further guidance on how, to “evaluate the toxicity of the spilled substance and how the toxicity may change when spill response countermeasures (products) are used to combat the spilled oil.”

There is one paragraph in the appendix specific to dispersants, but it makes no mention of dispersant toxicity.

The extent of guidance provided on the toxicity of the “countermeasures” is limited to these two sentences:

The reader is reminded that adverse effects can occur both from spilled oil and the countermeasures used to control the oil. To determine the options that result in the optimal environmental benefit, the toxicities of various control options must be compared to each other and the toxicity of the spilled oil.

Again, no further guidance is provided.  Most of the references provided in the Appendix are oil industry reports and publications.

Count me skeptical, but it’s hard for me to imagine how responders using this guidance document – most of whom are unlikely to have any training or expertise in toxicology – would have a clue as to how to weigh the limited data on dispersant toxicity required of listed products (which at least are provided in a table on page 101).

If readers believe I’ve missed guidance or other information that is available or being used to make such decisions, please bring them to my attention.

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  1. James Richard Tyrer
    Posted June 25, 2010 at 6:47 pm | Permalink

    Have you read the MSDS for Corexit® 9500? It is basically just kerosene and sulfonate detergent — similar to household spray cleaners. Not something that I would want to drink. However, a Million gallons of it in a cubic Mile of water is about 1 PPM. At that concentration, is it harmful to anything? Also, you did not mention that it is biodegradable and it hastens the biodegradation of the oil.

  2. Christian Roselund
    Posted July 2, 2010 at 5:01 pm | Permalink

    Thank you Mr. Denison for this very important information.

    Mr. Tryer – do you live in South Louisiana, and are you one of us who are getting poisoned?

    Cubic miles of water is an irrelevant measurement. BP has been spraying these dispersants from planes, as well as subsea injection. Furthermore, have you read the National Institue of Heallth data on Corexit EC9527A? It includes "strong positive evidence" of birth defects, testicular damage and reproductive harm. BP used hundreds of thousands of gallons of it.

    The people from Alaska who lived through Valdez do not see Corexit as harmless, either 9500 or 9527.

  3. James Richard Tyrer
    Posted July 3, 2010 at 1:27 am | Permalink

    I do not live in the Gulf area, but I live in reality. The symptoms being reported by those being poisoned are those of inhalation of aromatic hydrocarbons (Benzene, Xylene, Toluene, Naphthalene). These, and other, aromatics evaporate from the oil on the surface of the water. The use of dispersant results in the oil mixing with the water and prevents this evaporation.

    Do you understand that only the dose make the poison? If you are having trouble with the dimension of a cubic mile, it is 1,086,101.913 Million Gallons. (about 1 Trillion Gallons, 1.0e+12)

    Yes, I understand that Corexit 9527 contains 2-Butoxyethanol which is found in some liquid detergents as well as other common household products including Windex. It is only a suspected teratogen and cacenogen, but that would require prolonged exposure at higher concentrations. Wikipedia says that it is relatively "nonvolatile" so it appears unlikely that people are exposed to much of it compared to the highly volatile aromatics.

    You say that BP (and the US Coast Guard) have used hunderds of thousands of gallons of it. Wasn't that the less toxic Corexit 9500? Again, the dilution in cubic miles of water is relevant.

    Your straw man argument proves nothing. I did not say that Corexit was harmless. It is moderately toxic. If the ingredients were as toxic as you falsely believe, they would not be in common household products. Kerosene, Windex, liquid detergent and laundry detergent are toxic, ingesting or inhaling them in sufficient quantity will result in poisoning, but they are only moderately toxic.

  4. Christian Roselund
    Posted July 5, 2010 at 6:01 pm | Permalink

    Are you seriously using Wikipedia as a source?

    According to journalists who attended a conference call with the EPA in early May, hundreds of thousands of gallons of 9527 were used (see Grist Magazine May 13, 2010). 9527 contains 30-60% 2-Butoxyethanol. BP continued to use more 9527 "as more stores were found" according to testimony by chemist Wilma Subra on June 7, 2010 (

    The initial hundreds of thousands of gallons (EPA has been imprecise) of 9527 were sprayed by planes before subsea injection began, making dilution irrelevant. We who live here got gassed.

    To repeat: the NIH data (which you apparently did not take the time to read) states a "strong positive evidence" of birth defects, testicular damage and reproductive harm. That's pretty strong language for a government agency. What more do you want? A gold plated plaque that says "causes babies to be born funny?"

    2-Butoxyethanol was removed from an EPA list of hazardous substances in 1994 under pressure by chemical and soap companies. If you think that the chemical companies are watching out for your best interests, I invite you to take a bath in Corexit and tell me how it works for you. It remains on a list of hazardous substances in California.

    We already have the EPA downplaying the hazards to our health, they don't need your help. Please do your homework before spreading false information on the web.