Summary of Public Comments Received on the Government of Canada’s Revised Risk Management Strategy for Polybrominated Diphenyl Ethers (PBDEs) and Draft Ecological State of the Science Report on Decabromodiphenyl Ether (decaBDE) (Bioaccumulation and Transformation)

The State of the Science Report for a Screening Health Assessment of PBDEs (also referred to as the human health screening assessment) did not identify a current risk to human health from PBDEs. The Government of Canada did, however, make additional information concerning PBDE flame retardants and human health available to the public on the “it’s your health” website: http://www.hc-sc.gc.ca/hl-vs/iyh-vsv/environ/pbde-eng.php

The human health screening assessment (Health Canada 2006) concluded that worst-case estimates of the exposure of Canadians to PBDEs are much lower than levels which caused adverse health effects in laboratory animals. Based on reported concentrations of PBDEs in ambient and indoor air, water, various foodstuffs, human breast milk and dust, along with standard reference values for six different age groups, including breast-fed infants, upper-bounding estimates of daily intake of total PBDEs (i.e., tetra- to decaBDE congeners) were calculated. Food (including breast milk) represented the principal source of exposure for the majority of the age groups (although dust was the principal source of exposure for the 0- to 6-month-old non-breast-fed age group). 

The control measures that the Government of Canada will be proposing to protect the environment from PBDEs are expected also to reduce human exposure.

PBDEs are sold and used in three commercial mixtures, PentaBDE, OctaBDE and DecaBDE, each containing two or more of the seven congener groups (see Figure 1 of the Revised Risk Management Strategy for composition of the commercial mixtures).  There are no known natural sources of PBDEs and the presence of these substances in the environment results primarily from human activity and the use of the commercial mixtures.   Accordingly, the assessments and the Revised Risk Management Strategy consider PBDEs found in the commercial mixtures, as effects associated with PBDEs are attributable to their use. 

All the documents mentioned in this response are found on the Management of Toxic Substances website at:
http://www.ec.gc.ca/toxiques-toxics/
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The contribution of dust to human PBDE exposure was included in the Human Health Screening Assessment published in 2006, which found that food (including breast milk) represented the principal source of exposure for the majority of the age groups (although dust was the principal source of exposure for the 0- to 6-month-old non-breast-fed age group).

The control measures included in the final Revised Risk Management Strategy, published jointly with this table, such as regulatory controls to restrict PBDEs in manufactured and imported products will reduce PBDE exposure from dust by restricting the amount of PBDEs that are incorporated into products. The Risk Management Strategy also includes biomonitoring to continue to monitor the exposure of Canadians to PBDEs from all sources, including vulnerable populations such as pregnant woman and northern communities.

The human health assessment (Health Canada 2006) concluded that worst-case estimates of the exposure of Canadians to PBDEs are much lower than levels which caused adverse health effects in laboratory animals.

However, the Government of Canada continues to monitor PBDEs in the environment and in humans. This data will be used as performance indicators of risk management actions, and to determine whether the Risk Management Strategy is meeting its objectives.  

Ongoing assessment and management of PBDEs in Canada and other jurisdictions, in concert with the December 2009 announcement by the three largest manufacturers of DecaBDE of their intention to phase out production and import of DecaBDE for the US market by 2013 is expected to significantly decrease the use of this commercial mixture in Canada in the next few years.

The Government of Canada is aware of the use of decaBDE in plastic pallets. In parallel with the findings of the State of Science Report on decaBDE, the phase-out of the decaBDE substance by industry in the United States, and the public comments received, the final Revised Risk Management Strategy for PBDEs (published jointly with this table) was revised to propose the inclusion of a broader range of control measures for PBDEs, including restrictions for decaBDE that apply to all products (not limited to electrical and electronic equipment as indicated in the March 2009 Risk Management Strategy).

A consultation document on the proposed regulatory controls for PBDEcontaining products is currently being prepared.  This document will provide a detailed outline of the proposed instrument, and will allow interested stakeholders to comment and provide feedback. This comment will be considered in the development of the proposed regulatory controls.

There is a need to ensure that toxic substances being regulated will not be replaced by equally hazardous ones.

Missing from the Revised Risk Management Strategy is a mechanism to ensure that decaBDE is replaced with a safer alternative.

The absence of DecaBDE from products in Canada conveys that in order to achieve the necessary level of fire resistance, other technologies and materials will be introduced, each with their own particular environmental footprint and potential risk.  The Revised Risk Management Strategy pays little attention to the inherent risk posed by chemical substitution.

Manufacturers should seek out their solutions, and if they find an alternative chemical, they should conduct studies to ensure it is safe.

The Government of Canada is in agreement with the points raised and the need for an orderly transition to safer products and technology. The Government of Canada is currently undertaking screening assessments of two important alternative flame retardants, tetrabromobisphenol A (TBBPA) and hexabromocyclododecane (HBCD). 

In addition, as part of the Categorization of the Domestic Substances List (DSL) that was completed in September 2006, approximately 4300 substances have been identified as requiring further action (e.g., through a process of risk assessment and risk management if needed).  This group includes substances which may have application as flame retardants.

The Government of Canada is currently considering ways to prioritize the assessment and management of substances remaining to be addressed. In this respect, approaches are being examined which would further consider the impacts of alternative substances.

The availability, cost and effectiveness of acceptable alternatives are considered as part of the risk management process in consultation with stakeholders. 

A consultation document on the proposed regulatory controls for PBDEcontaining products is currently being prepared.  This document will provide a detailed outline of the proposed instrument, and will allow interested stakeholders to comment and provide feedback. These comments will be considered in the development of the proposed regulatory controls, and any exemptions for critical uses will be considered.

Aligning Canada ’s Risk Management Strategy with the European Union RoHS (Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment) Directive 2002/95/EC is premature and unwarranted.

Aligning Canada ’s Risk Management Strategy with the European Union RoHS Directive is in agreement with the needs and capability of the many companies and suppliers in the Canadian electronics industry.

While the Government of Canada fully considers actions that are taking place in other jurisdictions, risk management actions are based on the findings of risk assessments undertaken by the Government of Canada. 

The final Revised Risk Management Strategy for PBDEs (published jointly with this table) proposes the inclusion of control measures for PBDEs in products, including restrictions for decaBDE that apply to products (not limited to electrical and electronic equipment as indicated in the March 2009 Risk Management Strategy). These revisions are broader than the restrictions currently in the European Union RoHS Directive, and were made following conclusions of the final State of Science Report on decaBDE (published jointly with this table), the public comments received during the consultation period and the voluntary phase-out by industry of the production of decaBDE substance, in the United States.

A consultation document on the proposed regulatory controls for PBDEcontaining products is being prepared.  This document will provide more details on the proposed instruments, and will allow interested stakeholders to comment and provide feedback.  These comments will be considered in the development of the proposed regulatory controls, and possible exemptions for critical uses will be considered.

As part of the proposed regulatory controls to restrict PBDEs in products, it seems unwise to allow for the re-use of non-compliant spare parts, given the environmental and health risks involved.  These products should be labelled as non-compliant. 

The provision allowing for spare parts should sunset after a fixed period of time (e.g. 5 years).  

This comment will be taken into consideration as part of the development of the proposed regulatory controls for PBDE containing products.  As above, a consultation document on these regulatory controls is currently being prepared. This document will provide further details on the proposed instrument, and will allow interested stakeholders to comment and provide their feedback.

As for health risks, the health assessment did not identify a current risk to human health from PBDEs.

The proposed Product Regulations will not provide adequate measures of protection to human health and the environment. 

It would be more protective for the Government of Canada to commit to a full ban on PBDEs in products (including in the textile sector).

A voluntary approach is the most responsible means to managing decaBDE.

The risk management objective for all seven groups of PBDEs that were added to Schedule 1 of CEPA 1999is to prevent the introduction of their manufacture in Canada and to minimize their release into the environment from all sources in Canada . The health assessment did not identify a current risk to human health from PBDEs.

In the final Revised Risk Management Strategy for PBDEs (published jointly with this table), the Government of Canada proposes stringent regulatory action for all sectors, including those covered by the Performance Agreement (plastics and textiles).  This revision from the March 2009 Risk Management Strategy is based on the conclusions of the State of Science Report on decaBDE regarding its potential to transform into forms slated for virtual elimination (tetraBDE, pentaBDE and hexaBDE congeners), the public comments listed in this table and the announcement of the voluntary phase-out of decaBDEby industry in the United States. As such, the proposed Performance Agreement ^[1] is no longer deemed an effective tool to manage the use of DecaBDE at manufacturing facilities in Canada , and will not be finalized for implementation.

If the restrictions become too stringent from the perspective of recyclers, they may stop accepting any materials containing PBDEs and this will create a disposal problem. 

The Revised Risk Management Strategy overlooks the risk for exposure from the waste recovery and reuse of products containing PentaBDE and OctaBDE.

The first comment will be taken into consideration while developing the regulatory controls to restrict PBDEs in products, in an effort to minimize adverse impacts of proposed controls on the recycling/refurbishment industry.   A consultation document on the proposed regulatory controls is currently being prepared.  This document will provide  more details of the proposed regulations and will provide interested stakeholders the opportunity to provide comments and feedback on any potential adverse impacts to the recycling industry.

Issues related to the recycling and reuse of products containing PBDEs are complex and are currently being examined at the international level under the Stockholm Convention on Persistent Organic Pollutants and the Convention on Long-range Transboundary Air Pollution (LRTAP) of the United Nations Economic Commission for Europe (UNECE). Canada is actively engaged in these discussions.  At the fourth Conference of the Parties (COP4) of the Stockholm Convention, the convention added provisions allowing the continued recycling and reuse of products containing the listed PBDEs (contained in the PentaBDE and OctaBDE commercial mixtures) until 2030. For more information on this listing decision, please consult the COP4 documents of the Stockholm Convention at: http://chm.pops.int/Convention/COP/hrMeetings/COP4/
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The Government of Canada is developing a risk management strategy for the waste sector (i.e., landfills, incinerators and recycling facilities) that will include PBDE-containing products and other toxics at end-of-life. This strategy will aim to minimize the quantities of PBDEs released to the Canadian environment through the disposal or recycling of products containing PBDEs.  As part of the development of one of these strategies, the Government of Canada is presently collecting information on waste and recyclable materials processing facilities in Canada .  PBDE's are also included in the Chemicals Management Plan (CMP) Environmental Monitoring Program and are being monitored across Canada in landfill leachate to determine the concentration of PBDEs released from these sites. Environment Canada plans to continue to monitor PBDEs and other toxics over the next few years, and will use the information collected as a performance measure of the risk management actions implemented.

Furthermore, as waste management also falls within provincial jurisdiction, many Canadian provinces have already passed province-wide legislation that requires manufacturers, importers and sellers to ensure take-back and recycling services for designated electronic products that they sell. Existing provincial programs are administered by: Electronics Stewardship Association of British Columbia (ESABC), Alberta Recycling Management Authority (ARMA), Saskatchewan Waste Electronic Equipment Program (SWEEP), Ontario Electronic Stewardship (OES), and Atlantic Canada Electronics Stewardship (ACES) for Nova Scotia. These programs continue to divert many tonnes of electronic waste from landfill to environmentally sound material recovery and recycling operations.

A multi-instrument approach for the risk management of PBDEs was selected to minimize releases of PBDEs from all sources to the environment.  The Performance Agreement was developed as an early action initiative of the Chemicals Management Plan and to complement regulatory instruments outlined in the Risk Management Strategy. 

Ongoing assessment and management of PBDEs in Canada and other jurisdictions, in concert with the December 2009 announcement by the three largest manufacturers of DecaBDE of their intention to phase out production and import of DecaBDE for the US market by 2013 is expected to significantly decrease the use of this commercial mixture in Canada in the next few years. The Risk Management Strategy for PBDEs has been further revised in response to these events as well as the public comments received on the March 2009 version of the Strategy.  The Risk Management Strategy now  proposes the inclusion of broader restrictions on PBDE containing products, including restrictions for decaBDE in a wide range of products (not limited to electrical and electronic equipment as indicated in the March 2009 Risk Management Strategy). As a result, the proposed Performance Agreement ^[2] is no longer deemed an effective tool to manage the use of DecaBDE at manufacturing facilities in Canada , and will not be finalized for implementation.

The findings of the draft Ecological State of the Science Report on decabromodiphenyl ether (decaBDE or BDE209) have been updated further for the final report since the time of its publication in March 2009, and are considered current.

The Risk Management Strategy originally published in 2006 was revised to take into consideration the results of the Ecological State of the Science Report. The final revised Strategy, published along with this table, was further revised to propose broadening the application of control measures restricting PBDEs in manufactured and imported products to include restrictions on decaBDE in a wide range of products (not limited to electrical and electronic equipment as indicated in the March 2009 Risk Management Strategy).

The timeline for risk management actions outlined in the final revised Strategy follows the  regulatory process under the Canadian Environmental Protection Act, 1999(CEPA 1999).

Conclusions within the State of the Science report are subjective, not based on strong and transparent scientific criteria, and unsubstantiated based on the weight of scientific evidence.  The subjective approach to risk management contained in the proposed State of the Science report contradicts Canada ’s well-respected process for chemical evaluation.

There is no scientific basis for proposing a ban on the use of decaBDE in electrical and electronic equipment.

There is not enough information linking decaBDE to increases in risk or impacts to the environment.

Further study on decaBDE is needed prior to taking action.

The conclusions of the Ecological State of the Science Report are based on published findings which are reviewed in the context of a weight of evidence evaluation.  The evaluation is not a risk assessment and does not provide a detailed critical review of all studies considered.  However, the quality of the included studies was reviewed and uncertainties were noted and considered in the production of the conclusions.

A weight-of-evidence approach is standard for chemical evaluations conducted under the Canadian Environmental Protection Act, 1999 (CEPA 1999). This approach accounts for multiple lines of evidence in the identification of issues in determining whether a substance may have harmful properties or pose a risk.

In the case of decaBDE an in-depth analysis relevant to bioaccumulation and transformation was conducted. The quality and quantity of available scientific evidence, determination of the adequacy and/or limitations of studies and a qualitative weighting of all relevant data, taking into account factors such as rigour, consistency and plausibility of observed outcomes, was applied. 

With regards to bioaccumulation, factors such as low assimilation efficiency and potentially metabolic transformation appear to be important determinants of accumulation of decaBDE in organisms.  Several studies indicate that decaBDE is clearly available for uptake and has potential to accumulate in biota to levels which we consider to be high, although uptake observed under laboratory settings  is generally shown to be low and subject to rapid excretion. As such, the available data do not show that decaBDE meets the numeric criteria for bioaccumulation as set out in the Persistence and Bioaccumulation Regulations under CEPA 1999.  The evaluation also shows that it is reasonable to conclude that decaBDE may contribute to the formation of lesser brominated PBDE products in organisms; potentially those which are bioaccumulative.  Laboratory studies relevant to environmental conditions also indicate that decaBDE may transform via processes of photolysis and biodegradation to products (both PBDE and other products) which may be bioaccumulative.

In the 2006 ecological screening assessment, PBDEs were assessed as a group, but consideration was also given to the commercial products and to the individual congeners. 

The rationale for conducting a class assessment for PBDEs  included:  that their constituents had an identical base structure; as commercial mixtures, there was overlap with respect to their constituents;  there was evidence suggesting that under some circumstances higher brominated PDBEs may debrominate to form lower brominated PDBEs in the environment and in biota; and that historically, these products were used concurrently, they  co-occur in the environment and any environmental risk would result from their combined presence in the environment.

The Ecological State of the Science Report on decaBDE, focused on decaBDE alone, in order to provide an in-depth analysis and clarify the status relevant to bioaccumulation and transformation of this specific congener.

The Ecological State of the Science Report summarizes the findings showing that decaBDE is extremely persistent without obvious transformation in environmental media such as sediments or soils over a span of several years. However, this does not preclude the potential for transformation in the environment. Laboratory studies confirm that biodegradation half-lives of decaBDE in sediments appear very slow and may range from approximately 6 -50 years.  However, a study examining historic levels of PBDEs in sediment cores taken from a Swiss Lake show that despite the high persistence observed in the levels of decaBDE, environmental debromination of decaBDE is a relevant issue, as shown by analyses of congener patterns, and the occurrence of PBDE congeners such as BDE202 which is usually not present in the commercial DecaBDE and OctaBDE products.  

Laboratory-based photolysis studies also demonstrate transformation to lower brominated PBDEs, as well as to other transformation products like polybrominated dibenzofurans (PBDFs) and unidentified substances.  As noted in the Ecological State of the Science report, one would expect only a very small proportion of the decaBDE reservoir in the environment to be susceptible to photolytic debromination, and that biodegradation appears possible but at a very slow rate. Thus, one may expect subtle indications of transformation of decaBDE in the environment which may be masked by the current congener patterns which are dominated from the use of the commercial Penta- and OctaBDE formulations. As well, the infrequent analysis of higher brominated PBDEs like octa- and nonaBDEs would make it difficult to detect or confirm transformation to these PBDEs. 

Recent Norway studies indicate declining levels of lower brominated PBDEs coinciding with continued commercial DecaBDE use.

Patterns of lower brominated congeners found in the environment are consistent with PentaBDE which is no longer in use, suggesting that degraded commercial DecaBDE is not the source of these lower congeners in the environment. 

A number of studies that are cited by EC as evidence for abiotic debromination used methodology that would be unlikely in a natural setting – e.g., photolysis in lab with solvent mixture, dust particulates not exposed to solvent, and no data to confirm photolysis of decaBDE in dust to the brominated BDEs found in biota, how photolysis applies to soil and sediment in natural environment etc.  What triggers decaBDE debromination in the lab may not apply to environment.

Data generated by laboratory studies, while important indicators for guiding future research, do not represent real world evidence and need to be substantiated by environmental field data.

The Ecological State of the Science evaluation also considers laboratory photolysis studies which expose decaBDE while dispersed in solvent to natural or artificial sunlight unrepresentative of conditions for transformation in the environment. This review and the final PBDEEcological Screening Assessment noted that a number of these studies showed transformation to the tetra-, penta-, and hexaBDEs.

However, laboratory-based photodegradation studies which expose decaBDE adsorbed to particulates in air, water or dispersed natural solvents like humic and fulvic acids (not concurrently in solvents) relevant to environmental conditions, provide a useful indication of the potential for transformation in the environment. Under natural conditions, it is expected that decaBDE will be found primarily bound to solids in air, on the surface of soils or other substrates, or in water.  Some of these studies also demonstrate transformation by photodegradation of hexaBDEs, as well as possible formation of tetra- and pentaBDEs at trace levels. The report recognizes that only a very small proportion of all decaBDE in the environment would be available for photolytic transformation.

Furthermore, studies showing biodegradation of decaBDE, for instance in activated sludge or soil, are considered to be relevant to the environment. The evaluation recognizes the uncertainty relevant to the extrapolation of laboratory results to the environment, but considers studies simulating environmentally relevant processes and conditions to be indicative of transformation in the environment.

Environment Canada is correct in concluding that decaBDE does not have significant potential to bioaccumulate / biomagnify, based on lab and field studies of decaBDE. 

Background levels of decaBDE in biological samples appear to be 2 ng/g lw.  The congener decaBDE has no particular affinity to lipids.

The conclusion that evidence has shown that decaBDE is bioaccumulative and/or biomagnifying in food chains, is not supported by the evidence presented in the report that decaBDE has limited bioaccumulation potential due to low dietary assimilation efficiency and metabolism.

Characterizing the levels of potential for accumulation in biota as “high” is purely subjective and considered inappropriate unless it is put into context.

Lab studies corroborate poor decaBDE uptake, circulation, systemic distribution and elimination mainly as the parent molecule.

Reports of extensive metabolism in rats are not based on structural identification of products of Phase 1 and Phase 2 metabolism, poor parent molecule recovery and/or lack of recognition of fecal binding.

Long term dose studies in rodents show a lack of toxicity.  Lifetime (2 year) studies show no evidence of toxic or bioaccumulative metabolites. Such studies should be added to the State of the Science Report.

Recent in vitro studies show no microsomal metabolism of decaBDE.

The Ecological State of the Science report describes typically low uptake of BDE209 and rapid elimination of the parent molecule. Where appropriate, the Report recognizes the uncertainty in rat studies showing extensive metabolic transformation.  For instance, with respect to Mörck et al. (2003) it notes that the analysis for hydroxyl- and hydroxymethoxyBDEs was qualitative and their identification was inferred. Nevertheless, one cannot discount that the metabolites could have been formed as reported in the subject study. The formation of such metabolites has also been shown in other studies reviewed in the report, adding support for their formation in mammalian systems.

An evaluation of decaBDE toxicity was considered beyond the scope of The Ecological State of the Science Report.  In July 2006, the Government of Canada published its final screening assessment on polybrominated diphenyl ethers (PBDEs). The environmental screening assessment examined various supporting information and developed conclusions based on a weight-of-evidence approach as required under subsection 76.1 of CEPA 1999and concluded that all assessed PBDEs (tetra- to decaBDEs) were entering the environment in a quantity or concentration or under conditions that have or may have an immediate or long-term harmful effect on the environment or its biological diversity and thus meet the criterion under paragraph 64(a) of CEPA 1999.

The Ecological State of the Science Report recognizes that there is variability and uncertainty in the findings of some metabolic transformation studies; however, the report also finds that some in vitro studies (e.g., utilizing fish liver microsomes) have shown rapid and substantial (e.g., up to 65% over 24 h) transformation of decaBDE to lower brominated PBDEs including hexaBDE. This is also considered evidence of microsomal metabolism of decaBDE in wildlife.

The Ecological State of the Science Report indicates that overall uptake of decaBDE in fish and mammals generally appears to be low

and the formation of lower brominated PBDEs also appears to be a fraction (typically on the order of a few percent) of the total amount of decaBDEadministered to the organism.  But, some rodent studies have made inferences respecting the formation of bound and/or hydroxylated and hydroxymethoxylated PBDEmetabolites which may account for a potentially larger proportion of decaBDE dosed to organisms (potentially up to approximately 45 – 65% of the total dose of decaBDE).

These findings are considered significant given the potential for the formation of bioaccumulative transformation products in vivo. Studies utilizing mixtures were considered appropriate to consider; however, uncertainties in the findings were noted where appropriate.

There is concern with the limited ability of the Persistence and Bioaccumulation Regulations and CEPA 1999to address substances, such as decaBDE, that biomagnify and bioaccumulate in terrestrial species and through terrestrial food chains.

There is concern that despite the report findings that decaBDE is bioavailable and may accumulate to potentially high levels in certain species, and contribute to the formation of bioaccumulative /potentially bioaccumulative transformation products, the report does not find that decaBDE meets the thresholds in the Persistence and Bioaccumulation Regulations.  This also highlights a more far-reaching problem with this CEPA regulation relying too heavily on out of date scientific criteria, which this commenter believes the Government of Canada has acknowledged (joint EC/HC response to 2008 Petition).

The bioaccumulation analysis of decaBDE has highlighted the limitations with CEPA’s provisions regarding bioaccumulation and the need for a thorough assessment of the thresholds and procedures used to analyze bioaccumulation under CEPA.

Although the Persistence and Bioaccumulation Regulations under the Canadian Environmental Protection Act, 1999 (CEPA 1999) do not explicitly refer to measures of biomagnification or measures of bioaccumulation in terrestrial species and food chains, concerns of very bioaccumulative substances, including those which biomagnify, are captured by the Toxic Substances Management Policy (TSMP), a Government of Canada policy.  Criteria in the Persistence and Bioaccumulation Regulations are based on those in the Policy that guide the Government of Canada in determining whether substances should be identified for virtual elimination, or life cycle management. In keeping with this policy direction, actions may be taken to control substances which are shown to biomagnify, or accumulate from sources other than those which are aquatic based. This policy also provides latitude for the federal government to take action on a substance should it be shown to transform in the environment to forms which are bioaccumulative.

The Ecological State of the Science Report finds that decaBDE does not specifically meet the criteria for bioaccumulation under the Persistence and Bioaccumulation Regulations and also does not find unequivocal evidence that the substance is subject to biomagnification in aquatic or terrestrial food chains. There is further supporting evidence indicating a limited potential for uptake and some metabolism of decaBDE in organisms; these attributes would limit bioaccumulation and biomagnification in wildlife. However, the report also concludes that decaBDE may transform in the environment (e.g., by processes of photodegradation, metabolic transformation and biodegradation) to products which may be bioaccumulative. Thus, the findings of the Ecological State of the Science report on decaBDE guided by the policy direction provided under the current provisions of the TSMPprovide justification for expanded risk management of decaBDE.

There is no regulatory obligation to base a decision on bioaccumulation using log K_ow determinations.  Professional judgment should be applied to evaluate the intrinsic properties of the substance and ecosystem under consideration.  While log K_ow is well known to be an indicator of the potential for bioaccumulation based on passive diffusion, its application requires substantial professional judgment due to various inherent limitations when used for this purpose.  Although a log K_ow value may meet the numeric criterion identified in the Persistence and Bioaccumulation Regulations, the substance may not bioaccumulate significantly due to such factors as metabolic transformation and/or poor uptake efficiency. This approach is consistent with guidance identified in the Toxic Substances Management Policy (Government of Canada 1995a, b) which provides discussion of the uncertainties relating to the use of K_ow for making conclusions on bioaccumulation. For decaBDE, the available science reviewed in the Ecological State of the Science Report on decaBDEdoes not support a conclusion that this substance meets the bioaccumulation criteria set out in the Persistence and Bioaccumulation Regulations.

Although a substance, such as decaBDE, may be measured in the tissues of wildlife at levels which we consider to be high, this does not necessarily mean that it should be considered bioaccumulative.  In fact, such concentrations may be reflective of high environmental exposure resulting in low ratios of exposure concentrations to tissue concentrations.  The intent of the Ecological State of the Science Report on decaBDE was to flag this issue since high substance concentrations in tissues could be problematic from other perspectives (e.g., greater availability of the substance for potential metabolic transformation to potentially bioaccumulative and persistent substances).

There is concern that the report’s bioaccumulation interpretation based on ratio analysis is not consistent with the original intent of the 1995 Toxic Substances Management Policy (TSMP) for bioaccumulation, which indicated the potential of a substance to bioaccumulate “can be expressed” by ratios, not that they are the only way to determine bioaccumulation.

The comment notes that EC documentation calls for “expert opinion” to be considered, in addition to bioaccumulation criteria.

The comment concludes that apparent uncertainties and measurement difficulties with decaBDE are not a reason to narrow the definition of bioaccumulation to a ratio based analysis – that this misconstrues the meaning of bioaccumulation under the TSMP.

There is recognition that other evidence may be used to make inferences respecting a substance’s potential for bioaccumulation, and for this reason, the Ecological State of the Science Report also considered biota concentrations as well as metabolism and uptake studies in addition to the ratio based analysis of bioaccumulation data. The Ecological State of the Science Report found that there are various attributes which support a decision that decaBDE does not meet the criteria for bioaccumulation in the Persistence and Bioaccumulation Regulations. For instance, the available evidence indicates that the substance is typically shown to have low uptake efficiency and may be metabolized to some extent in wildlife. Although some studies show that decaBDE may accumulate in wildlife to concentrations considered to be high, most available surveillance data indicate that decaBDE is found at much lower concentrations in organisms, and frequently at non-detectable levels.  Even tissues from the same species taken from similar locations do not consistently show that decaBDE is accumulating to higher concentrations.

In consideration of the weight of evidence, which is consistent with the interpretation of how to apply the TSMP and the Persistence and Bioaccumulation Regulations, it is concluded that decaBDE is not sufficiently bioaccumulative in wildlife to satisfy the criteria in the Persistence and Bioaccumulation Regulations.