IN THE UNITED STATES
All dispersant products used in the US
must be listed on the US EPA National
Oil and Hazardous Substances Pollution
Contingency Plan (NCP) Schedule.
Approved dispersants must meet minimum
effectiveness requirements and the manufacturer
must report toxicity test results.
The US Regional Response Teams (RRT) may
preauthorize the use of dispersants in the waters of
their region. Most of the RRTs have established pre-
authorized zones for dispersant use.
During an incident, the Federal On-Scene
Coordinator (FOSC) has the authority to approve
dispersant use. This will often be considered in
consultation with an Incident-specific RRT, made up
of federal, state and local trustees.
Effectiveness monitoring is required during
Dispersants are approved as a response option in
many countries around the world.
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Dispersants are products used in oil spill response to enhance natural microbial
degradation, a naturally occurring process where microorganisms remove oil from the
environment. All environments contain naturally occurring microbes that feed on and
break down crude oil. Dispersants aid the microbial degradation by forming tiny oil
droplets, typically less than the size of a period on this page (<100 microns), making
them more available for microbial degradation. Wind, current, wave action, or other
forms of turbulence help both this process and the rapid dilution of the dispersed oil.
The increased surface area of these tiny oil droplets in relation to their volume makes
the oil much easier for the petroleum-degrading microorganisms to consume.
Dispersants can be used under a wide variety of conditions since they are generally
not subject to the same operational and sea state limitations as the other two
main response tools — mechanical recovery and burning in place (also known as
in-situ burning). While mechanical recovery may be the best option for small, near-
shore spills, which are by far the majority, it has only recovered a small fraction of
large offshore spills in the past and requires calm sea state conditions that are not
needed for dispersant application. When used appropriately, dispersants have low
environmental and human health risk and contain ingredients that are used safely in
a variety of consumer products, such as skin creams, cosmetics, and mouthwash
(Fingas, et al., 1991; 1995).
This fact sheet summarizes the process and decision-making required for dispersant
use approval in United States waters. It is intended to provide a clearer understanding
of dispersants, how their use is authorized, and their consideration in a decision-
making process based on a Net Environmental Benefit Analysis (NEBA). For more
information on NEBA, see
Fact Sheet #6 — Assessing Dispersant Use Trade Offs
Introduction to Dispersants
Fate of Oil and Weathering
Toxicity and Dispersants
Dispersant Use Approvals in the
Assessing Dispersant Use Trade-offs
Aerial and Vessel Dispersant Operations
Subsea and Point Source Dispersant
Dispersants Use and Regulation Timeline
Dispersant Use in the Arctic Environment
Fact Sheet Series
I Oil Spill Prevention
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APPROVALS IN THE UNITED STATES
When an oil spill occurs, some adverse impacts are inevitable
because the environment has been exposed to the spilled oil,
even if it is only at the microscopic level. One primary goal of
a spill response is to lessen any anticipated impacts using
knowledge gathered from years of experience and research.
For each spill, the available response options must be rapidly
evaluated using a Net Environmental Benefit Analysis approach
to determine which option or set of options, given incident-
specific conditions, will result in the best outcome for the
environment and which countermeasures will help minimize
any adverse effects. In general, the pre-designated lead
federal official, known as the Federal On-scene Coordinator
(FOSC), relies on the results of the incident specific NEBA that
will be performed by the responsible party in conjunction with
scientific advisors, in order to determine whether dispersant
use is appropriate.
The main categories of response options available for use in
a spill include: 1) on-water mechanical containment, recovery
and removal using booms, skimmers, etc.; 2) application of
dispersants; 3) controlled (in situ) burning of floating slicks; 4)
monitoring a slick for possible future action.
The objective of NEBA is to determine which option or
combination of options should be used to remove/recover
the spilled oil in order to mitigate the spilled oil’s overall, or
net, impact on resources and the environment. Because oil
spreads quickly, on-scene conditions (wind and water currents)
will determine the movement of the oil for large on-water spills.
The response options used must be considered in relation
to area-specific resources at risk, e.g., biological resources,
environmentally-sensitive habitats, and human-use areas such
as tourist beaches and marinas. Time-critical choices must
be made about which option or options can be implemented
immediately and effectively to manage potential impacts.
The collective worldwide spill response experience over the last
40 years has demonstrated that mechanical recovery alone is
generally not able to recover a majority of spilled oil especially in
large offshore spills. According to the US Office of Technology
Assessment and by actual experience during a spill, mechanical
methods typically recover no more than 10-15 percent of the oil
after a major spill in open water (OTA, 1990). In more contained
areas, e.g., a marina, a higher level of recovery may be achieved
especially in calm conditions.
Because the majority of the spilled oil offshore likely cannot be
recovered before spreading over a much larger area, decisions
need to be made about how to best manage floating oil using
a combination of response options for the incident-specific
conditions. A key goal of a spill response is to prevent an
oil slick from coming ashore. A decision to use dispersants
involves evaluating the potential trade-offs: decreasing the
expected risks to wildlife on the water surface and shoreline
habitats while increasing the potential risk to organisms in the
water column. Sometimes the use of dispersants is the only
viable response option.
The National Oil and Hazardous
Substance Pollution Contingency
The National Oil and Hazardous Substance Pollution
Contingency Plan (NCP) provides the “playbook” for oil spill
response in the U.S. The organizational framework of the U.S.
National Response System (NRS), as defined in the NCP is
Figure 1 (see next page).
The National Response System (NRS) is the mechanism for
coordinating response actions by all levels of government in
support of the Federal On-Scene Coordinator (FOSC) and
is divided into national, regional, and area levels. The NRS is
composed of the National Response Team (NRT), Regional
Response Teams (RRTs), FOSC, Area Committees (AC), Special
Teams, and related support entities. The basic framework for the
response management structure is a unified command system
that brings together the functions of the federal government,
the state government, and the responsible party (i.e., the spiller)
to achieve an effective and efficient response, where the FOSC
retains authority (
40 C.F.R. § 300
Furthermore, the NCP specifies the response actions and
and as well as the requirements for federal, regional, and area
contingency plans. One component of these responsibilities is
the development, selection, and implementation of response
actions for each region including the procedures for the use of
dispersants in spill response.
To address the needs for specific regional and area dispersant
use policy, each RRT and AC defines their minimum
requirements for the use of dispersants for an oil spill response.
It should be noted, however, that the FOSC can approve the
use of dispersants for safety reasons or in pre-approval areas
without the need for concurrence of the RRT. If appropriate, the
FOSC may include the use of products, including dispersants,
to help limit the spread of the oil and to lessen its impact on the
environment and potential resources at risk.
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The NCP Product Schedule
The Clean Water Act (CWA) Section 311(d)(2) and Section
4201(a)(G) of the Oil Pollution Act of 1990 requires that the
President maintain a schedule of chemical and biological spill
response countermeasures, including dispersants, that may be
used to respond to oil spills to ensure that the products are
used effectively and appropriately; the President has delegated
this authority to the U.S. EPA.
Approval to use dispersants on an incident begins with the
authorities laid out by the NCP. Subpart J (Use of Dispersants
and Other Chemicals;
40 C.F.R. § 300.910
) of the NCP is the
U.S. EPA’s Product Schedule for these regulated chemical and
biological countermeasures (EPA online, 2011a). The Product
Schedule is EPA’s listing of the chemical and biological agents
that have submitted the required information and, once listed,
may be considered for approval by the FOSC for use during
Dispersants and other response countermeasures are required
to be on this schedule if they are to be considered for use during
a response. For a dispersant or other chemical to be listed on
the Product Schedule, the manufacturer must submit specific
test results and supporting technical data on their product to
the U.S. EPA as defined in
40 C.F.R. C.F.R. § 300.915
effectiveness and toxicity.
To be listed as a dispersant, the product must demonstrate
a minimum effectiveness value as measured by a standard
dispersant effectiveness test using defined test oils. Specific
toxicity testing data, physical properties and other information
about the product must also be submitted. In the wake of
the response to the Macondo Well release the EPA now
Toxicity and Effectiveness Data Summaries
product categories on the Product Schedule, which facilitates
comparisons and evaluations of products and categories.
The National Response System (NRS) organization as dictated by the NCP.
National Response Team (NRT)
15 Federal Agencies
National Planning & Coordination for spills
Provide assistance & guidance for the
Regional Response Team (RRT)
Regional planning and coordination of
including use of dispersants
Includes state & local representation
Federal On Scene Coordinator
Pre-designated federal ofﬁcial assigned
the authority to coordinate and direct an
oil spill response
Decision-maker for dispersant use
Oversees development of the for
Develop area planning for response
use of dispersants
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NOTE: Inclusion on the Product Schedule does NOT
indicate a recommendation or endorsement of any listed
product by the EPA or other federal agencies; it only
means that the manufacturer has submitted the required
information for inclusion on the schedule and it may be used
during a response.
Authorizations for Dispersant
Use in the U.S.
The following sections outline the various responsibilities
imposed on various agencies and organizations by the
regulatory changes in U.S. policy.
The Oil Pollution Act (OPA 90)
The Oil Pollution Act (OPA 90) was signed into law in August
1990 and improved the nation’s ability to prevent and respond
to oil spills by establishing provisions that expanded the federal
government’s ability, and provided the money and resources
necessary to respond to oil spills. In addition, OPA 90 provided
new requirements for contingency planning both by government
The NCP was expanded in a three-tiered approach: 1)
the federal government is required to direct all public and
private response efforts for certain types of spill events; 2)
Area Committees, composed of federal, state, and local
government officials, must develop detailed, location-specific
Area Contingency Plans (ACP); and 3) owners or operators of
vessels, pipelines, and facilities that transport, handle, or store
oil in certain quantities must prepare their own Response Plans.
As a means to address the requirements of OPA 90, a three-
fold strategy was used nationally (with some location-specific
modifications) to determine the regional and area planning and
preparedness requirements for the use of dispersants in U.S.
waters. This included:
Pre-spill planning, including evaluating the potential use of
products listed on the NCP Product Schedule, was delegated
to the RRT and AC decision-making bodies under the direction
of OPA 90. The RRTs were charged with developing pre-
authorization plans (also called pre-approval agreements)
in advance of an incident to identify the following areas:
Pre-authorized zones — areas where dispersants can
Case-by-case basis zones — areas where the FOSC
e.g., EPA, Department of Commerce (DOC)/NOAA,
Department of the Interior (DOI), and states, to determine
whether dispersant use is appropriate.
Exclusion zones — areas where dispersants are not to
Many RRTs have limited dispersant applications in marine
waters to water depths greater than 30 feet (10 m) and in
most coastal areas there is an additional requirement that the
dispersants be used in areas more than 3 nautical miles (5.6
km) from shore which means use in near shore areas and
estuaries is generally excluded.
Because these products are used to treat oil spills in open
ocean waters, the FOSC is provided by the US Coast Guard
(USCG). At this time, there is no dispersant available that is
approved for use in United States freshwater environments.
Pre-authorization means that if agencies have signed a pre-
authorization agreement, and if a spill meets the conditions
outlined in the applicable Regional Contingency Plan (RCP),
then the FOSC can approve dispersant use within specified
zones as soon as he/she believes it will result in greater benefit
than if they are not used.
To develop the pre-authorizations for dispersants, the RRT
representatives from U.S. EPA and the states with jurisdiction
over the state waters for each region, along with U.S. DOC
and DOI natural resource trustees, conduct a NEBA review
of the risks and benefits associated with chemical dispersant
applications. This evaluation also requires an assessment of the
likely impacts to threatened and endangered species residing
or passing through the areas being considered by the RRT
Each RRT will approve or disapprove the pre-authorization
agreements which will be incorporated into the RCP and the
associated USCG ACPs. Most pre-authorization plans outline
zones where, or conditions under which, dispersants may be
used. These are generally based on geographic area, distance
from the shoreline, water depth, and/or season and may be
limited by the presence of specific environmentally sensitive
resources (e.g., a marine sanctuary).
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The designation of pre-authorization areas, and the discussions
that led to their establishment, can be very important steps
towards a timely and effective spill response.
NOTE: The pre-authorization status for each region is
on the RRT regional
links. Additional information on regional decision-making
relative to dispersant use can be obtained from the USCG
Vessel Response Plan Program under “
Maps and Photos –
Dispersant Usage Map
Approvals During an Incident — Case-by-Case
needs no approval for the use of dispersants as a protective
measure. Otherwise, when the FOSC determines that the use
of dispersants is required and there is no pre-authorization for
their use, he/she may only use them with the concurrence of the
EPA representative to the RRT and state RRT representatives in
consultation with the DOC and DOI natural resource trustees.
This group of state and federal agency decision-makers is also
known as the Incident-specific RRT.
In most instances where a spill occurs in areas where pre-
authorization is not in place, the USCG FOSC requests a
decision by the incident-specific RRT within four hours of his/
her initial request so that a dispersant decision is rendered
in time to execute a dispersant operation and effective
application, also known as the “window of opportunity”. For
more information on this topic refer to
Fact Sheet #3 — Fate
of Oil and Weathering
After the initial consultation, the incident-specific RRT can agree
defined use conditions, or they can veto their use.
As stated, many RRTs have established areas within their
region where dispersants may not be used. Many of these
exclusion zones are located within state waters, typically in
areas less than 3 nautical miles (5.6 km) from shore or with
water depths shallower than 30 feet (10 m). The primary
reason dispersants could be used in these areas is if human
health or public safety is at immediate risk from the incident.
As mentioned earlier, the FOSC needs no approval for the
use of dispersants as a protective safety measure.
Dispersants are considered a primary response option in
a number of countries and are approved for use in many
countries, including the U.K., South Korea, Australia, Egypt,
France, Greece, Indonesia, Italy, Japan, Malaysia, Norway,
Singapore, Spain, Thailand, and a number of coastal African,
South American, and Middle Eastern countries (ITOPF). The
requirements for application are country-specific and must
be verified prior to application.
In the U.S., dispersant approvals include operational monitoring
requirements to assist the Unified Command in determining
the effectiveness of dispersant application. This can include
a definition of when dispersant use should be discontinued,
e.g., definition of a threshold which if reached would result in
stopping the dispersant operation. Ideally, the decisions to use
and discontinue the use of dispersants are made based on
objective scientifically-based research and effectiveness testing
and involve the components associated with a relevant NEBA.
Periodic operational monitoring allows the individuals managing
the incident, i.e., the Unified Command (UC) to assess the
effectiveness of dispersant use and determine whether their
use should be continued.
In the U.S., monitoring of dispersant effectiveness and
gathering potential exposure data is performed according
to the Special Monitoring of Applied Response Technologies
(SMART) protocols, a methodology that involves the use of
three tiers of monitoring. In order of increased requirements:
Tier I — Visual observations by trained observers,
Tier II — On-water visual observations and fluorescence
spectrometry at a single depth to measure oil
concentrations under treated slicks; and
Tier III — On-water visual observations, fluorescence
sample collection to monitor horizontal and vertical
spreading of the dispersed oil.
Updated Regulatory Status
In 2010, during the response to the Macondo Well release in the
Gulf of Mexico, large volumes of dispersants were applied to
offshore surface oil by aircraft and vessel (National Commission,
2011). Following this use, the RRTs were instructed to review
their existing dispersant use policies and update their Regional
PAGE 6 OF 6
Contingency Plans (RCPs) to reflect the knowledge and
This was also the first instance where dispersants were injected
into the oil release site where it exited the seafloor. Although
this use of dispersants, known as subsea injection, had been
previously studied and considered for possible use, this was the
first documented successful application of the approach. As a
result, subsea injection of dispersants is now considered by the
coastal RRTs to be a potential option to mitigate the adverse
effects from subsea oil discharges offshore. The National
Response Team (NRT) has issued monitoring guidance for
subsea use of dispersants. For more information on the subsea
application, refer to
Fact Sheet #8 — Subsea and Point
Source Dispersant Operations
Testing the Effectiveness of Spill-Treating Agents: Laboratory Test
Development and Initial Results. In: Proc. 1991 International Oil Spill
Conference. API. Washington, DC.
Fingas, M. F., D. A. Kyle, N. D. Laroche, B. G. Fieldhouse, G. Sergy, and R.
G. Stoodley. 1995. “The Effectiveness of Spill Treating Agents.” The Use
of Chemicals in Oil Spill Response, ASTM STP1252, P. Lane, ed. ASTM,
National Commission on the BP Deepwater Horizon Oil Spill and Offshore
Drilling (National Commission). 2011. Deepwater: The Gulf Oil Disaster
and the Future of Offshore Drilling – Report to the President. 398
pages. Available from:
National Response Team Response Committee. 2002. NRT-RRT Fact
Spill Response? 4 pp.
Office of Technology Assessment (OTA), U.S. Congress. 1990. Coping
OTA-BP-O-63. 70 pp.
U.S. EPA. 2007. Subpart J: The National Oil and Hazardous Substances
Pollution Contingency Plan (NCP) Product Schedule. 2 pages.
Available online from:
U.S. EPA online. 2011a. “EPA Emergency Management – NCP Product
U.S. EPA online. 2011b. “Oil Pollution Act Overview.” Last modified
U.S. Coast Guard (USCG) online. 2011. USCG Homeport Vessel
2011. Available from:
International Tankers Owners Pollution Federation Limited (ITOPF),
Profiles. Available online at:
U.S. Department of the Interior (DOI). 1963. Federal Water Pollution
Floating Oils. July 5, 1963. 1 page.
The current version of the NCP Product Schedule can be viewed at: