Committee report June 2-3, 2015 - Chemicals Management Plan Science Committee
Chemicals Management Plan Science Committee
The Science Committee (the Committee) was requested to prepare a response to the following Charge Question:
The Committee offers the following responses for consideration by the Departments, organized according to the following scheme:
1) Comments on the concept of the proposed Framework
Prior to the meeting, the Committee was provided with a detailed review (an "Objectives Paper") summarizing the proposed Framework. The paper did an excellent job of summarizing and explaining the proposed approach and was discussed extensively during the meeting. In addition, Louise Stedman, National Industrial Chemicals Notification and Assessment Scheme (Australia), an ad hoc Committee member, summarized the lessons learned by one competent authority (Australia), which is proceeding with a tiered approach to its mandate of assessing chemicals. Based on these inputs plus a detailed discussion during the meeting, the Committee concluded that the approach was innovative, conceptually sound and relevant to the Departments' mandate. The Departments recognized that the proposed CMP approach will have numerous challenges, including the following: inconsistent data availability, tight regulatory timelines, the need to maintain consistency across assessments and over time, and communication with internal and external stakeholders.
The Committee recognized that expediencies and economies of effort will be required to assess 1500 substances in the third phase of the CMP (2016-2020). The Committee reviewed the proposed framework with that in mind, but commented that expediency also needs to be balanced with the need to innovate. For example, new approaches are under development now that could have greater application in the future. As such, the Framework should provide guidance to assessors, but should not be overly prescriptive; maintaining flexibility was seen as a key aspect to successful implementation of the Framework.
2) Comments on potential challenges associated with the proposed five levels of complexity, plus suggestions on specific assessment approaches
For ease of reference, the proposed Framework is reproduced here:
The Committee reviewed the Framework and agreed that in the form in which it is currently presented it may not clearly communicate the idea of using the simplest suitable assessment approach (the use of arrows in the figure implies a movement through sequentially higher levels, where the higher levels represent increasing confidence in the conclusion). In their subsequent discussions, the Committee cautioned against the use of the word "levels" which has a built-in hierarchical meaning. They pictured the assignment of the initial "level" (subsequently referred to in this report as an "Approach") of assessment as a "highway", with various decision /stopping points to assign an assessment into a definite "bin". Each bin is expected to be an appropriate and fit-for-purpose assessment for that substance/group that is based on specific determinants/decision criteria (as per the bullet points in the commentary in the current Framework) with the knowledge that these determinants will be open to review, modification and update.
2.1) Comments on Approach 1 assessments
The Committee noted that even if it was deemed appropriate for another ("better-placed") program to conduct the assessment and subsequent management of the substance (for example, under different legislation such as the Pest Control Products Act, the Food and Drugs Act and the Canada Consumer Product Safety Act) the decision to adopt this program evaluation may not be applicable to both EC and HC, depending on the quantities in commercial use and the use patterns. (The Committee recognized that this potential difference between the Departments in assessment approach applies to all substances yet to be assessed in the CMP.)
The alternate program should be scheduled to report by 2020.
The Committee queried whether the process to reopen the assessment based on any new relevant exposure/hazard information exists if a previous decision has been made under the Canadian Environmental Protection Act, 1999 (CEPA 1999).
- Approach 1 decisions, that is, the basis for referring the decision to the alternative program, still need to be communicated even if the decisions are made outside of a CEPA context.
It is not anticipated that substances being assigned to this Approach 1 assessment would require any new data generation on either hazard or exposure.
2.2) Comments on Approach 2 assessments
Defining or providing guidelines for "low potential for exposure" is useful for both human health and environment assessments and needs to be justified and explained in a transparent manner. The Committee recognized that this is a challenge, but that it is essential if this Approach is to be useful.
The Committee queried whether environmental exposure would still be considered "low" if occupational exposure is high. In subsequent discussion with the Departments, it was confirmed that occupational exposures are not considered within the CMP; there are federal/provincial/territorial processes in place to ensure appropriate communication of occupational hazards when relevant.
- If all uses can be confirmed to be in "closed systems", that is, with no emissions, then an Approach 2 assessment may prove to be of much utility although a process is required to ensure that any proposed change in use/exposure pattern can be evaluated by the Departments. The Committee expects this to be manageable given the availability of current regulatory instruments (for example, Significant New Activity Control - a well-developed process under CEPA by which hazardous substances with currently well-contained exposure characteristics (or with no current uses in Canada) are identified by regulation to prevent new uses being introduced without the manufacturer/importer reporting the intention to the Departments), but this expectation needs to be monitored and confirmed by the Departments over time.
There is a possible dichotomy wherein the toxicity on the environmental side may be routinely predicted (for example, using OASIS, a model in widespread use to predict hazard to the environment) but on the human health side a decision could be made at Approach 2 on the basis only of low exposure. Human evaluations should generally also consider a modelled estimate of hazard. The development of approaches for polymers or based on international "low risk" criteria such as those used in Australia is suggested. The Committee noted that it could be argued that the Threshold of Toxicological Concern (TTC) does comprise a conservative estimate of hazard, but that this will require justification and documentation.
The Committee agreed that the TTC is a potentially valid approach (note that as part of their discussion on the TTC concept, the Committee noted that it incorporates a three-tier classification process by which substances are grouped according to their structural features and anticipated ease of metabolism into innocuous end products, with Class 1 being of least concern. See Cramer G. M., Ford R. A. and Hall R. L. (1978) Estimation of toxic hazard: A decision tree approach. Food and Cosmetics Toxicology 16, 255±276).
The TTC approach, as currently described in the literature, is used primarily in the absence of relevant hazard information. If, as proposed, the Government intends to extend the TTC approach to include substances where hazard data already exist, the Department should consider expert consultation prior to advancing the concept.
The Committee suggested that additional review may be required for those substances for which direct human exposure is low but environmental exposure is predicted to be high, to ensure that additional exposure via the food chain is accounted for appropriately.
In general, the Departments will need to carefully review the issue of transparency associated with communicating all decisions associated with this assessment approach (as for all other decisions made using this Framework), including the justification for specific cut-off values developed internally (for example, ratios of exposure levels to effects levels) and used in the rapid screening by the Departments to draw conclusions on CEPA toxicity.
2.3) Comments on Approach 3 assessments
Approach 3 represents risk assessments conducted where an aspect of the assessment does not result from a de novo hazard or exposure assessment. This would include assessments conducted based on:
The Committee suggests that this approach requires a pilot exercise to confirm the concept, using data-rich substances that have information available from multiple approaches (e.g. biomonitoring and "traditional" exposure data, or traditional hazard data and high throughput screening or other in vitro data) to compare the approaches as part of the assessment. Confidence in the approach will be obtained by using examples to demonstrate that this approach does not result in an imbalance between false negatives and false positives. The Committee prepared the following Table as a summary of the efficiencies and challenges.
|Hazard assessments and/or data summaries prepared by another international organization.||If the fundamental considerations in the previous assessment are not questioned, the effort requires primary review only of those studies which may have lower effect levels than those previously reported.||To be credible, hazard assessments reapplied from other jurisdictions will need to be updated to include key information produced since the international assessment was prepared. The process of updating the assessment may be challenging depending on the transparency of judgments applied in the original assessment. These assessments would necessarily rely on exposure assessment from the Canadian context.|
|Use of biomonitoring data to avoid the need to estimate exposures using a traditional exposure evaluation at the risk assessment stage.||Avoids the need to estimate exposures using a traditional exposure evaluation at the risk assessment stage.
In cases where multiple substances are assessed as a group, the biomonitoring information on some members of the class (for example, for data-rich substances) can be used to increase confidence in the strength of the overall assessment.
|Biomonitoring data do not provide source attribution for significant sources of exposure. In instances where risk management is needed, traditional exposure source information may still be necessary to allow for credible, appropriately targeted, risk management.
Use of Biomonitoring Equivalents (BE) for assessment will require significant additional high-tier information in the form of toxicokinetics and other data to complete the assessment. Substances which are rapidly metabolized or excreted may be particularly challenging in this regard. An analysis of the expected level of effort and an "accuracy" comparison between de novo exposure assessment and BEs should be conducted.
|Use of non-traditional endpoint data derived from HTS tests as a key (or only) component of the hazard assessment.||In instances where multiple substances are assessed as a group, the HTS data can be used to bridge and increase confidence in the strength of the group assessment.||Use of HTS information for assessment will require significant additional high-tier information in the form of toxicokinetics and other data to complete the assessment.
Substances which are rapidly metabolized or excreted may be particularly challenging in this regard.
2.4) Comments on Approach 4 assessments
It is expected this Approach would have been the standard "default" under previous phases of the CMP. However, under this Framework, an Approach 4 assessment would only be needed if the assessment could not be conducted using Approaches 1-3.
2.5) Comments on Approach 5 assessments
Approach 5 represents the most complex form of assessment and may include cumulative or additive considerations and probabilistic approaches. Comments made for Approach 4 assessments apply here; in addition, it is anticipated that many assessments identified within this approach will be unique, thus requiring an even more deliberate approach at the problem formulation phase (to ensure that the proposed approach is fit for purpose and viable) and at all subsequent steps. Some of the substances likely to be assessed at this level may have ubiquitous exposure; hence, consideration of potential substitution opportunities (for alternative substances with similar chemistry and functional use potential) could be considered during problem formulation.
3) Comments on how to best operationalize this Framework and its potential ongoing role post-2020
The Committee offers the following comments under a series of sections:
3.1) Operationalizing the Framework and building confidence in assessments
The Committee noted that building confidence in application of the streamlined approaches described in the Framework will require demonstration of multiple levels and approaches on data-rich compounds. In this next phase of the CMP, the Departments will continue to focus on using grouping of chemicals approach to provide required efficiency of assessment. Using data-rich chemicals in any given group to facilitate the analysis of data-poor chemicals in that group is a potential approach for building confidence in decisions across the group.
Operationalizing the Framework and building confidence in assessments will be further facilitated by systematic documentation of the approach level, assessment approach, and decisions to develop additional information. Information in the following table suggests possible elements for consideration for providing this type of systematic implementation.
|Element of Assessment||Key Considerations||Supporting Information and Documentation|
|Signal||Low versus high||Criteria based on exposure, hazard, human toxicity, ecotoxicity|
|Available information||Sparse versus rich||Exposure data, toxicity studies, mechanistic/other relevant data|
|Problem formulation||Simple versus complex||Low concern, individual compound, groups, mixtures, challenging substances|
|Analysis approach||Data driven versus mechanistic||Rapid screening, existing analysis, updated analysis, new analysis|
|Risk-based stop criteria||Low risk, high uncertainties versus high risk, low uncertainties||Examples:
|Product||Standard versus tailored||Standard language, standard tables summarizing evidence, quantified uncertainty|
|Value of information for action||Will more data, more analysis after a rapid screen change the decision?||More data after rapid screening for risk assessment; more analysis, more data after risk assessment for risk management|
3.2) Stopping criteria
The majority of the stopping criteria (discussed above) are continuations of existing processes to create a fit-for-purpose assessment that meets CEPA requirements. In addition some "process changes" may be used to build additional stopping criteria. For example, we suggest that when appropriate the Departments consider "de-connecting" their individual assessments in order to focus resources on substances of concern for each individual Department. It should be possible to design a "holding process" for publishing complete assessments from one Department (e.g. a State of Science report), with associated opportunities for external review, until such time as a consolidated assessment of all reports is finalized.
We expect that there will be additional focus on creating appropriate Problem Formulation packages as an initial step under the governance process that the Departments intend to set up. It is suggested that the Departments aim for maximum simplicity because, given the newness of this approach, assessors may tend to favour the more familiar type 4 or 5 Approach. Other major components of this process include: the capturing and sharing of specific learnings, conducting scenario-development exercises, and ensuring consistency across decisions. It is suggested that internal scientific evaluations be set up to assess consistency. Additional stopping criteria should be identified within a formal governance process.
3.3) Quantification of uncertainty
Characterizing and communicating uncertainty was previously addressed (in 2014) by the Committee; the concepts are unchanged. However, operationalizing the Framework is expected to require careful consideration of uncertainty for the selection on the appropriate approach as well as for providing confidence in the choice of stopping decisions.
3.4) Using the Value of Information (VOI) concept
The Value of Information (VOI) concept was previously discussed (in 2014) by the Committee as a potential best practice; its use should be more widely investigated as a test of whether additional information is required in order to justify a decision under CEPA section 64. The essential reasoning in the VOI approach is to determine, given what is currently known, how likely it is that additional information or analysis would change the decision outcome. For example, if existing information suggests that an section 64 "toxic" determination is a likely decision outcome, the most valuable information would be that which would potentially reverse this decision. The Committee recognizes that while the VOI concept would be difficult to operationalize, it will be more efficient than conventional approaches.
3.5) Assessment factors
The Departments may want to review their current use of Assessment Factors (Risk Quotients and Margins of Exposure, specific comparisons generally used by the Departments to compare hazard characteristics with potential exposure and thus draw conclusions on risk within a CEPA context), and determine whether some rules or guidelines can be developed for certain "non-standard assessments" and applied for future similar assessments.
3.6) New tools
The Committee highlighted the importance of maintaining flexibility in the Framework to allow for review, modification and update of assessment determinants.
The Departments described the potential use of the TTC concept. The Committee recognizes that this would constitute a new application of this approach in CEPA and considers it worthy of an extensive review because
The concept requires additional validation in the CEPA context.
Another potential new tool in the CEPA context would be to focus on creating standardized processes. These may take many forms, including standardized text, in addition to standardized assessment processes. The proposed Governance process would provide oversight and encouragement for standardization activities.
The Departments should actively seek out new tools for assessment under Approach 2 that incorporate both hazard and exposure for human health assessments.
3.7) Substance substitution activities
With the anticipated increase in more complex assessments, covering multiple substances with similar uses, it may be extremely helpful to anticipate potential substitute substances should the assessment of the initial substance result in a conclusion of CEPA-toxic. Enhanced communication between risk assessors and stakeholders may enable opportunities for such replacement substances to be identified and assessed as part of a larger assessment. The Committee understands that this approach requires additional planning. Consideration should be given as to where the evaluation of alternatives best fits into the Risk Assessment/Risk Management process.
3.8) Comments on post-2020 activities
The Committee did not address this question in detail but offered the observation that the proposed Framework appears to be sufficiently robust in concept that, provided the associated governance and learning processes remain built into the Framework, it will serve Canada well in the post-2020 period. An increased application of HTS data as a primary assessment tool may be expected post-2020 and the Departments are encouraged to continue to develop and test approaches to make the best use of emerging toxicological evaluation methods, including the ability to weigh data across multiple lines of evidence.
Respectfully submitted on behalf of the CMP Science Committee. The Committee wishes to thank two ad hoc members, Louise Stedman and Greg Paoli, for their valuable contributions.
Barbara Hales and Geoff Granville (Co-Chairs)
August 5, 2015
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