Vol. 150, No. 12 — June 15, 2016


SOR/2016-108 May 25, 2016


Regulations Establishing a List of Spill-treating Agents (Canada Oil and Gas Operations Act)

The Minister of the Environment, pursuant to section 14.2 (see footnote a) of the Canada Oil and Gas Operations Act (see footnote b), establishes the annexed Regulations Establishing a List of Spill-treating Agents (Canada Oil and Gas Operations Act).

Gatineau, May 19, 2016

Catherine McKenna
Minister of the Environment

Regulations Establishing a List of Spill-treating Agents (Canada Oil and Gas Operations Act)


1 The list set out in the schedule is established for the purposes of the definition spill-treating agent in section 2 of the Canada Oil and Gas Operations Act.

Coming into Force

2 These Regulations come into force on the day on which they are registered.

(Section 1)

List of Spill-Treating Agents


(This statement is not part of the Regulations.)


Canada has committed to modernize its offshore oil and gas regime by implementing an enhanced regulatory system and strengthening environmental protections. These Regulations support this initiative by establishing a list of spill-treating agents (STAs) acceptable for use in the event of an oil spill from an offshore facility.


Offshore oil and gas production is regulated by the Canada-Nova Scotia Offshore Petroleum Board (CNSOPB), the Canada-Newfoundland and Labrador Offshore Petroleum Board (C-NLOPB) and the National Energy Board (NEB). These regulatory bodies, hereinafter referred to as the Boards, ensure that operators comply with the statutory and regulatory requirements of the Canada-Nova Scotia Offshore Petroleum Resources Accord Implementation Act, the Canada–Newfoundland and Labrador Atlantic Accord Implementation Act and the Canada Oil and Gas Operations Act (COGOA), respectively, for the purpose of preventing and responding to spills in Canada’s offshore waters covered under the acts.

Spill-treating agents are substances that can be applied following an oil spill to help control the path the spill takes and to mitigate the effects of the spill on the environment. “Spill-treating agent” is a generic term which includes dispersants, herding agents, emulsion treating agents, solidifiers, bioremediation agents, and surface-washing agents. The deposit of STAs into Canadian waters is prohibited under a number of federal environmental statutes, including the Migratory Birds Convention Act, 1994, the Fisheries Act and the ocean disposal provisions of the Canadian Environmental Protection Act, 1999 (CEPA).

The Energy Safety and Security Act, which received royal assent on February 26, 2015, aims to strengthen the safety and security of offshore oil exploration and production through improved oil spill prevention, response, accountability and transparency. The Act amends the Canada-Nova Scotia Offshore Petroleum Resources Accord Implementation Act, the Canada–Newfoundland and Labrador Atlantic Accord Implementation Act and COGOA to allow for the use of STAs in the offshore under five conditions. Specifically, in the event of an oil spill, the Act lifts the legal prohibitions that would otherwise prevent the use of an STA if

For the purpose of this regime, section 14.2 of COGOA authorizes the Minister of the Environment to make a ministerial regulation establishing a list of STAs acceptable for use in Canada’s offshore. The Minister of the Environment will also work with the federal ministers of Natural Resources and Aboriginal Affairs and Northern Development Canada to develop another set of regulations defining in greater detail the conditions of use of STAs within five years of the Act receiving royal assent.


The Minister of the Environment has determined that the STA products listed in these Regulations are acceptable for use in Canada’s offshore. As a result, the appropriate regulatory bodies (CNSOPB, C-NLOPB, NEB) will be able to approve the use of one or more of the STA products listed in these Regulations under the conditions described above to respond to an oil spill.


Approach for the selection of products for inclusion on the list

The selection of products for inclusion in the Regulations was based on an assessment of the classes of STAs and identifying those products that are known in the spill response community to offer high efficacy with low toxicity. The evaluations considered documented real spill experience and scientific studies by the Department of the Environment, other government departments and international agencies, academia and industry.

The STAs included on this list have been studied over a period of decades under a variety of conditions and test methods to evaluate the functionality of STAs for use on oil spills and to develop test methods for comparing the relative effectiveness of products within a STA class. The listed products have consistently demonstrated best-in-class performance, and are typically selected as the representative product within their respective class of STA by oil spill researchers throughout Canada and the United States (U.S.). The Department of the Environment also considered the results of laboratory test methods used in other jurisdictions and tests related to different conditions of use (temperature, dose rate or water salinity) or variation in oil type or scale (using wave tanks and test basins) to validate their conclusions. Finally, the evaluation also considered documented experiences from field studies and actual spill response activities.

Ecological risk from STA use was assessed using a set of acute toxicity reference methods developed by the Department of the Environment, including both lethal and sublethal effects. As well, the product ingredients were compared to the toxic substances list in Schedule 1 of CEPA to identify components of known concern. Given the potential for products to be used during offshore, cross-border oil spill incidents, the National Oil and Hazardous Substances Pollution Contingency Plan (NCP) of the U.S. Environmental Protection Agency’s (EPA) was also reviewed to determine the compatibility of listed products between Canada and the United States.

The Department of the Environment STA test criteria and test methods

The scientific testing conducted by the Department of the Environment to identify the STAs listed in the proposed Regulations focused on assessing toxicity and effectiveness.

Toxicity is the inherent potential or capacity for a material or substance to cause an adverse effect on a group of selected organisms of a single species under defined conditions. Acute toxicity refers to adverse effects resulting from a single exposure to a substance or material, or from multiple exposures in a short period of time. In examining acute toxicity, scientists consider lethal as well as sublethal effects, that is, changes related to physiological processes, growth, reproduction, behavior and development as a result of exposure to the substance or material. An acute aquatic toxicity test typically measures either the proportion of organisms affected, or the degree of effect shown, after exposure to a specific test material or substance. Since no single test method or test organism can be expected to comprehensively represent all environmental impacts, scientists perform a combination of toxicity tests on different types of organisms to assess toxicity.

The use of STAs will generally result in only short-term exposure to affected species. The Department of the Environment scientists tested the STA products using the following standard Canadian reference methods targeting a range of species:

These reference methods are used by laboratories that are accredited by the Standards Council of Canada or the Canadian Analytical Laboratories Association, conforming to International Organization for Standardization (ISO/IEC 17025:2005) requirements aimed at ensuring that they are technically and scientifically competent and that test results are reliable. In addition, the scientific literature has been consulted to understand the current state of knowledge for laboratory, and real world use. The U.S. EPA has done extensive work on dispersant toxicity both with and without oil, including endocrine disruption.

Effectiveness measures depend on the class of STA. An effective dispersant is one that rapidly and comprehensively transfers oil from a slick at the surface down into the water column as small droplets. An effective washing agent enhances the removal of oil adhering to hard surfaces, such as rocky shorelines and human-made structures.

Dispersant effectiveness varies depending on several factors, including oil type, oil weathering state, sea energy, salinity, temperature and dispersant dose. A standard test is necessary to establish a baseline performance parameter so that dispersant products can be compared. However, laboratory test results cannot be considered an absolute measure of performance at sea where spill and sea conditions will vary; they must be supplemented with evidence from actual oil spill responses.

The Department of the Environment uses the following tests to evaluate dispersant effectiveness:

The Department of the Environment developed the Inclined Trough Test (ITT) to determine the effectiveness of surface-washing agents. This test measures the ability of a product to move oil away from a test surface. Specifically, a bead of oil is applied at the crease of a stainless steel trough and treated with a surface-washing agent, then flushed with water. The cleaning effectiveness of the surface-washing agent is determined by measuring the difference in weight of the oil before and after treatment. The U.S. EPA has identified the ITT for effectiveness testing under proposed changes to their National Contingency Plan. Efforts are underway at the Department of the Environment to develop an improved effectiveness test using natural substrates.

The Department of the Environment’s approach for evaluating STAs is consistent with those of other jurisdictions, notably the U.S. EPA. Like the Department of the Environment, the U.S. EPA examines the toxicity and effectiveness of STAs. (see footnote 2) With respect to toxicity, the U.S. EPA considers acute toxicity, but does not currently measure sublethal effects. Their approach may be broadened in the future to be made more similar to Canada’s approach by adding consideration of acute sublethal effects. The U.S. EPA is also assessing chronic effects based on experience gained through the Deepwater Horizon incident. (see footnote 3) The tests used by the U.S. EPA to measure acute toxicity are similar to those used by the Department of the Environment, with differences related to the target test species. The Department of the Environment has evaluated the acute lethality of the STAs listed in the proposed Regulations on several aquatic test species, including vertebrates and invertebrates. It has also tested sublethal effects to fertilization on echinoids and microbial growth inhibition. The U.S. EPA currently evaluates the acute lethality of the STA alone and in combination with fuel oil, on two marine species: a vertebrate (fish) and an invertebrate (shrimp).

With regard to dispersant effectiveness, the U.S. EPA uses a modified Swirling Flask Test (SFT). The U.S. EPA recently indicated that it is considering changing its approach to use the Baffled Flask Test (see footnote 4) (BFT). The Department of the Environment does testing with both the SFT and BFT. As noted above, the Department of the Environment uses its ITT to measure the effectiveness of surface-washing agents. While the U.S. EPA does not currently measure surface-washing agent effectiveness, it has proposed the use of the ITT. (see footnote 5)

STA products for listing

For these Regulations, the Department of the Environment scientists have conducted scientific evaluation and have identified two products (one dispersant and one surface-washing agent) known to offer best-in-class characteristics based on extensive long-term study, and demonstrated success during actual oil spill responses in other jurisdictions. The evaluations concluded that these products possess favourable characteristics as oil spill countermeasures and offer the potential for high efficacy coupled with low toxicity to biota in the marine environment. Therefore, the following STAs are included in the Regulations:

Amendments to the list of spill-treating agents

The Minister of the Environment may amend these Regulations by adding other STAs in the future. Other STA products will be tested for toxicity and effectiveness on the basis of criteria to be established relative to the best-in-class products. The Department of the Environment will also evaluate data available from other sources, such as the U.S. EPA’s NCP. Should new information become available that indicates a listed product poses a greater risk to the environment than originally estimated, the product can be removed from the Regulations.

In evaluating other STA products for possible addition to these Regulations, the Department of the Environment may also conduct supplemental studies as warranted to ascertain risks and potential ecological impacts related to product use, such as amendment of oil mobility that may affect fate and transport of the treated oil, and the toxicity of degradation by-products. A significant weight will be given to lessons learned from experience gained during actual spill response, as available.

“One-for-One” Rule and small business lens

The Regulations will not impose an administrative or compliance burden on business, and as a result, neither the small business lens nor the “One-for-One” Rule apply.


The Regulations Establishing a List of Spill-treating Agents (Canada Oil and Gas Operations Act) fulfills the definition of a “spill-treating agent,” as contemplated in the Energy Safety and Security Act.

As required by the Cabinet Directive on the Environmental Assessment of Policy, Plan and Program Proposals, a preliminary scan was conducted which concluded there would be no expected important environmental effects, either positive or negative; accordingly, a strategic environmental assessment is not required.


The Regulations Establishing a List of Spill-treating Agents (Canada Oil and Gas Operations Act) sets out the spill-treating agent (STA) products that may be considered by regulators under the Canada Oil and Gas Operations Act and the corresponding accord acts for response to spills from offshore petroleum exploration and production. The Regulations do not in itself regulate the deposition of STAs. The Regulations also do not impose any costs or burden on stakeholders, as the STAs are not a compulsory element of a spill response plan, but are intended to provide options for spill response that must be permitted in an authorization by the relevant regulator prior to use. Therefore, a limited consultation approach was taken. Any regulation developed in the future for the purpose of authorizing deposits of STAs that could impose costs or burden on stakeholders would be subject to separate consultations.

The Regulations were prepublished in the Canada Gazette, Part I, on July 4, 2015, for a 30-day public comment period. In addition, 130 stakeholders, including provincial and municipal governments, Aboriginal groups, industry associations, and environmental groups, were notified in writing that the proposed Regulations were available for comment in the Canada Gazette.

A total of 3 553 submissions were received and taken into consideration during the 30-day public comment period. Parties who submitted comments included municipal governments, an Aboriginal group, an oil producer and an industry association, spill response product suppliers, environmental non-governmental organizations, and members of the public.

Of the total submissions received, 15 submissions were received from organizations and approximately 212 from private citizens which referred to many elements of the proposed Regulations as well as the Regulatory Impact Analysis Statement (RIAS) published with the proposed Regulations on July 4, 2015. The remaining submissions were generated through an online petition. A summary of the comments received during the above-mentioned public comment period and how they have been addressed are as follows:

Purpose of the Regulations

There were a number of comments received from the general public, environmental non-governmental organizations, and a municipal government related to the overall purpose of the Regulations Establishing a List of Spill-treating Agents (Canada Oil and Gas Operations Act). The comments question the rationale for creating a regulation to enable the use of spill-treating agents (STAs) in oil spill response, suggesting instead that the focus should be placed on recovery and remediation of the oil, or the complete halt of offshore oil production altogether. Some comments asserted that STAs do not offer an environmental benefit, while others expressed concern that access to STAs would lead to an overreliance on chemical products and diminish efforts to physically recover and naturally remediate the oil.

Response: The Minister of the Environment acknowledges that direct recovery of spilled oil is the preferred response option, as this usually reduces the environmental impact with the least risk. However, mechanical recovery is rarely sufficient to fully address a significant spill; this is especially true in remote and technically challenging offshore regions. The inclusion of STAs to expand the available response options is necessary to enable a spill to be addressed to the maximum possible extent in order to protect the overall integrity of the environment. As echoed by the comments received, this is not without risk. For this reason, the Regulations identify only those STA products that offer high efficacy and low toxicity for use under appropriate conditions as established under the Canada Oil and Gas Operations Act (COGOA). The actual use of STAs as part of a spill response operation falls under the oversight of the relevant regulator.

Process to select products to be included on the list

Comments were received from environmental non-governmental organizations and a municipal government questioning the approach taken to select products for the list. One comment raised concern that selecting the “best-in-class” is a relativistic approach that could lead to the inclusion of products that do not offer a net benefit to the environment, but included as the best option within a STA product class. The need was expressed for defined, absolute criteria and an explicit process to evaluate products for inclusion in the Regulations, and also for the removal of products from the Regulations. One comment requested that the product assessments be made public, while another requested disclosure defining the issues that would merit further study, to avoid arbitrary influence. There was also a suggestion that all STA products be evaluated prior to making a selection for those to be included in the Regulations.

Response: The Minister of the Environment is satisfied that the inclusion of the two products listed in the Regulations is appropriate. A best-in-class approach was selected to populate the Regulations, supported by the extensive weight of evidence currently available for the two listed products from laboratory tests, research studies and real-world experience. The evaluation of other products would not affect the inclusion of the two products named in the Regulations. Unnecessary delay to determine which of the other available products are appropriate for inclusion in the Regulations introduces its own risk, as STA use would remain unavailable to responders until the Regulations are published. The development of a formal evaluation process and criteria for identifying additional products to be included in, or removed from, future revisions of the Regulations is ongoing. In addition to any criteria to be established for selecting products, the Minister reserves the right to explore any additional aspects related to effectiveness or environmental risks that come to her attention that may impact the suitability of an STA for inclusion in the Regulations. The publication of future versions of the Regulations will be supported by a RIAS to publicly identify the basis for the inclusion of products in the revised Regulations.

Process to authorize use of products under the Regulations

There were a number of comments received from environmental non-governmental organizations, a municipal government, and the oil production industry raising concern regarding the authorization process to use products listed in the Regulations. Several comments raised concern that listing of a product in the Regulations will pre-authorize the use of an STA and reduce regulatory oversight or due consideration for the actual conditions present at the time of a spill. Other comments questioned the rationale for relying on decision-makers to determine appropriate use of an STA during the stress of an emergency, some suggesting that response plans be proven prior to a spill event with knowledge of all impacts from use. There was also concern that the requirement to consult with the Minister of the Environment would delay time-sensitive decisions and impede the optimal response. Other comments suggested that the regulation for conditions of use should be in place prior to the publication of the Regulations to list eligible products. Another comment suggested that the authorization of STAs should also include a protocol to terminate the use of an STA once authorized.

Response: The listing of a product in the Regulations Establishing a List of Spill-treating Agents (Canada Oil and Gas Operations Act) is only one element of the criteria required to allow use in a spill response. It does not imply pre-authorization for use, nor does it diminish regulatory oversight. The inclusion of an STA in an operator’s response plan must first be permitted by the relevant Board as part of the authorization to operate, and further granted approval from the Chief Conservation Officer at the time of a spill, contingent on meeting the criteria outlined above in the Background section. Although an assessment of general conditions may indicate the potential for a net environmental benefit from STA use during planning and preparation, it is necessary to validate a net environmental benefit exists in the context of prevailing conditions at the time of spill due to the variability of both the physical environment and the state of the biota within it. It is not possible for response plans to be proven in advance of a spill, or to have knowledge of all possible outcomes from use of an STA. Leaving the final approval of the use of an STA to the time of a spill retains flexibility to ensure prevailing conditions are the basis for the decision. It is for this reason that it is essential that the regulator consult with the Minister prior to approval of an STA during the transition period to ensure that the regulator has access to current information and expertise to determine if a net environmental benefit exists. The Minister provides coordination during environmental emergency events through the National Environmental Emergencies Centre (NEEC) to facilitate the timely delivery of information and expertise from the Department of the Environment and other government departments. The consultation available from the Minister is sufficient until formal regulations on conditions of use are created. Finally, the termination of STA use once approved is a responsibility of the relevant regulator, in consideration of the requirement to achieve a net environmental benefit.

Evaluation of risk

Comments were received from the general public, environmental non-governmental organizations, and a municipal government that expressed concern with the evaluation of the toxic effects of STAs. Commenters expressed concern that the toxicity tests performed on the products proposed for the Regulations are inadequate to provide an accurate assessment of the risk to the ecosystem. Comments suggested the need for chronic testing in addition to acute tests, and another indicated the value of toxicity testing of an STA product in combination with oil. Another comment questioned the use of the CEPA toxic substances list to assess risk.

Response: The Minister of the Environment is satisfied that the data available from acute and sublethal toxicity testing by EC reference methods on a range of taxa (vertebrates, invertebrates and microbes), and from studies on real-world experience and other international laboratory and field research, is sufficient to provide a relative assessment of the aquatic toxicity to determine suitability for inclusion in the Regulations. The broader impact of a STA to the ecosystem is also a function of the nature and scope of its use, which must be considered in the determination of net environmental benefit. As noted in the Description section above, additional EC test methods and potential alternatives are being evaluated to develop the final criteria for toxicity assessment, and include tests on mixtures of oil and dispersant. Chronic toxicity testing may also be considered in the future, however the anticipated exposure to STAs is short in duration, placing greater emphasis on sublethal effects from acute exposure. For the purposes of screening STA products, the CEPA toxic substances list is an effective means to quickly identify ingredients known to pose a significant environmental risk and to potentially eliminate them from further consideration; however, it does not in itself provide an assessment of toxicity.


An environmental non-governmental organization and a First Nations organization expressed the obligation to consult with potential stakeholders, specifically First Nations and coastal municipalities. One of the commenters asked if there would be consultation in the future related to the publication of future revisions of the Regulations.

Response: The Regulations do not impose a direct risk to the community, as the exclusive purpose is to identify products that may be considered for use in oil spill response. Consultation with stakeholders potentially impacted by the specifics of a spill should be conducted at the project application stage and through the spill response management process.

Impact on stakeholders

An environmental non-governmental organization suggested that the Regulations will impose a regulatory burden on stakeholders impacted by the use of a STA on an oil spill. The comment indicates an administrative or compliance burden on business and government stemming from the indirect consequences of STA use.

Response: The Regulations to identify products for oil spill response does not impose a direct regulatory burden. Oversight for the actual use of STAs is provided by the relevant regulator, and any consequential claims for damages related to an oil spill must be sought under the liability regime defined in the Canada Oil and Gas Operations Act.

Addition of products in the Regulations

A large number of comments were received from individuals, the oil production industry, spill-treating agent distributors and a non-governmental organization requesting the inclusion of additional products in the Regulations. These included additional dispersants, surface washing agents, herders, bioremediation products and sorbents. Some included the identity of specific products, while others referred to a class of STA generally.

Response: The composition of the initial Regulations is intended to provide low-risk options to operators in the most relevant STA classes while the process to evaluate and select products for future amendments of the Regulations is being developed. In the context of current and imminent offshore production activities, the STA class having the most potential for use is dispersants, with possible application for surface-washing agents. The other classes of STA are less developed for spill response, and in lower demand. The use of sorbents is not impacted by these Regulations, with the exception of solidifiers, which are a special type of sorbent.


There were several comments received from academics, scientists and concerned citizens under the umbrella of non-governmental organizations, as well as the general public, that have questioned the rationale for including dispersants in oil spill response. Many of the comments presented arguments regarding the inherent and potential risks of dispersant use to the environment and human health, and questioned the benefits to be derived from dispersant use, often providing references from the literature in support. In general, the comments asserted that the risks associated with dispersants, both known and unknown, are simply too great to justify the inclusion of any dispersant product in the Regulations.

Response: The Minister of the Environment is satisfied that there are conditions, specifically in regions of Canada’s offshore, under which the impact of a spill may be mitigated through the use of dispersants. The listing of dispersant products is necessary to enable responders to have access to all appropriate options to reduce the impact of a spill on the environment. The legislation authorizing these Regulations provides the necessary safeguards to ensure that dispersants are used only when a net environmental benefit will be achieved, balancing the risk associated with dispersant use against the anticipated impact from the spill if left untreated.

Threats to aquatic species and sensitive ecosystems following dispersant use

Several comments were received from the general public and environmental non-governmental organizations raising concern regarding the toxic threat to specific species, classes of organism, aquatic organisms in general, and to sensitive ecosystems, such as the Gulf of St. Lawrence and the Arctic. Some stakeholders suggest that dispersant use will increase the toxic burden imposed on the oceans from the oil spill, enhance the concentration of polycyclic aromatic hydrocarbons (PAHs) from the oil in the water column, and increase the distribution of oil in the environment.

Response: The potential for increased exposure to components of the oil by aquatic organisms following the use of dispersants is a known risk associated with their use. It is for this reason that the relevant Board’s Chief Conservation Officer must make a determination whether use of the STA is likely to achieve a net environmental benefit in the particular circumstances of the spill in order to approve dispersant use. The assessment of net environmental benefit must consider the risks posed by the spill to the environment as a whole for each of the available response options, including the risks of environmental harm should dispersants not be used. While the use of a dispersant may increase the extent of harm due to a spill to the aquatic environment, this is done to mitigate harm elsewhere and minimize the damage overall. This approach is suitable for the protection of all ecosystems.

Corexit products

The vast majority of comments were received from the general public responding to an online petition posted by an environmental group opposing the inclusion of “Corexit” in spill response. In addition, there were comments received from environmental non-governmental organizations, a municipal government, oil spill product manufacturers and distributors and a First Nation organization questioning the inclusion of Corexit products in the Regulations. Most referred simply to “Corexit” without specifying a product or STA class. This created ambiguity, as there are three common Corexit products in addition to other less well known formulations. Corexit EC9500A, a dispersant, and Corexit EC9580A, a surface-washing agent, are both named in the Regulations. The other well-known product is a dispersant known as Corexit EC9527A, which is not included in the Regulations. Based on the context of the comments received, the comments are understood to refer to either or both of the dispersants and not to the surface-washing agent Corexit EC9580A. The comments expressed objection to the inclusion of Corexit products in the Regulations generally, on the basis that Corexit is toxic to humans and marine life and there are safer alternatives. Many provided one or more select literary references to support their view. A few comments also noted that Corexit is banned in other jurisdictions and may soon be banned in the United States.

Response: The Minister of the Environment is satisfied, based on the current evidence considered, that Corexit EC9500A is a suitable dispersant appropriate for inclusion in the Regulations for use in Canadian offshore waters in response to an oil spill. A safer, more effective alternative which would have undergone the rigour of years of study and real-world response is not known. The decisions by other jurisdictions, based on their own conditions and requirements, do not preclude a decision by the Minister to address Canadian conditions and requirements. Corexit EC9500A is currently listed on the United States National Contingency Plan. The United States is a major partner in spill response with potential cross-border spill response implications, and the potential for changes in its status is only speculation at this time.

Human health

There were a number of comments received from the general public, several environmental non-governmental organizations, and a municipal government that expressed concern that dispersants pose a risk to human health, that the risk is greater than from the oil itself, and that prior to listing in the Regulations, the health risks must be better defined.

Response: The objective of the Regulations is to establish a list of spill-treating agents acceptable for spill response. The party responsible for responding to an oil spill is charged with ensuring the safety of its responders, and the general public, during response operations using appropriate safeguards and with the oversight of the relevant regulator. A major study has been undertaken by the United States National Institute of Health (NIH) to better determine the effects of large-scale dispersant use. The results of this study will be followed closely for the implications to occupational health and safety of responders and use near populated areas, but is not expected to preclude the appropriate use of dispersants to protect the environment.

Dispersant fate in the environment

Comments were received from the general public and an environmental non-governmental organization raising concern that dispersants do not degrade in the environment, and may inhibit the natural degradation of oil. The implicated concern is that dispersants may persist in the environment, and may extend the duration of the impact from an oil spill by delaying the natural degradation of the oil.

Response: The chemical ingredients found in Corexit EC9500A are additives commonly found in foods and household products that have not been identified as posing an elevated risk to the environment. The influence of the dispersant on the biodegradation of oil has not been established definitively; however, it is important to note that the core motivation for using dispersants is not to enhance oil degradation. The primary objective of treatment with dispersants is to shift the distribution of an oil spill from the water surface down into the water column to divert the oil from impacting more environmentally sensitive habitat, and allow dilution to reduce the impact to aquatic species exposed to the oil. A net environmental benefit may be determined for dispersant use regardless of a delay in oil degradation.

Testing for dispersant effectiveness

Environmental non-governmental organizations provided comments suggesting that the effectiveness tests indicated in the RIAS are insufficient for evaluating dispersants. One of the comments questioned the reliance on laboratory tests that are not representative of field conditions. Another comment suggested including testing at multiple temperatures to reflect the range of Canadian marine conditions, and favoured the use of the Swirling Flask Test (SFT) over the Baffled Flask Test (BFT) due to the perceived unrealistically high mixing energy imparted by the BFT.

Response: The use of laboratory tests to evaluate dispersant effectiveness is necessary to impose controlled conditions for legitimate comparison between products. Given the variability of environmental conditions, it is not practical to establish standard field conditions for testing. In general, the relative ranking of effectiveness for dispersant products is consistent between laboratory tests and with those obtained from wave tanks and at sea. Varying the temperature of the test provides guidance to establish a dispersant’s effective range to inform a determination of the net environmental benefit; this has been completed between 0 °C to 25 °C for the product listed in the Regulations. As indicated in the Description section above, both the SFT and BFT tests were used to provide varied mixing energies in the evaluation of effectiveness in the laboratory.

Monitoring of dispersant fate in the environment

A comment from a non-governmental environmental organization indicated the necessity of including environmental monitoring of the fate of dispersed oil in the environment following dispersant use. The group asked who is responsible for the monitoring, what are the protocols, and for how long?

Response: Environmental monitoring is an obligation of the party responsible for an oil spill, with oversight provided by the regulator to ensure appropriate measures are taken, both in process and duration. Expertise from the relevant federal departments is available to the regulator to assist in the determination of appropriate measures related to the circumstances of a particular spill, and also to provide independent monitoring activities as required.


A question was received from an individual regarding the meaning of the word “deleterious” used in Part I of the Canada Gazette.

Response: The term “deleterious” has a specific meaning in the Fisheries Act to indicate a substance that may cause harm, and was used to indicate those STAs that are prohibited from use. It is acknowledged that the use of this term is too narrow in scope, as there are potential prohibitions under a range of legislative acts. The use of the term has been removed in the present document.


Dr. Carl Brown
Emergencies Science and Technology
Science and Technology Branch
Department of the Environment
335 River Road
Ottawa, Ontario
K1A 0H3
Email: ec.sust-informations-ests-information.ec@ canada.ca