The Canada/US Programs intend to use the classification scheme outlined in this document as a starting point to increase the utilization of analogue/read-across information in the assessment of new substances regulated under CEPA and TSCA. The Canada/US Programs will determine whether the proposed use of analogue/read-across information by notifiers is appropriate and valid. It is expected that as scientific knowledge increases, additional layers or tiers will be added to the proposed classification scheme, likely targeting more specific endpoints (e.g., tiers based on toxicological modes of action). As has been the practice under the RCC Nanotechnology Initiative, additions or changes to the nanomaterial classification scheme will be done in collaboration with stakeholders.
The Canada/US Programs intend to increase their understanding of hybrid nanomaterials (also called second and third generation nanomaterials) and of bionanomaterials which are increasingly being seen in the marketplace; although there have been notifications for hybrid nanomaterials, no notifications for bionanomaterials have yet emerged as noted in section 3.7. It is expected that within 3-5 years scientific knowledge will advance enough to support identification of the physiochemical parameters necessary to develop a class for these substances, as well as the potential usage of analogue/ read-across information within those classes.
Until that time, the Canada/US Programs will continue to evaluate hybrid nanomaterials on a case-by-case basis; additional discussions are needed between the Canada and US New Substances/Chemicals groups to further develop strategies to address hybrid nanomaterials.
The Canada/US Programs acknowledge that there is some uncertainty with the scientific foundation of this proposed classification scheme and the information necessary to validate this approach. However, it is expected that the proposed classification scheme, based on known science and endorsed and validated by stakeholders, will foster research on these nanomaterial classes to help to validate and further refine the physicochemical parameters and the boundaries proposed for them.
The research community is invited to help better the regulatory decision making of nanomaterials by generating data on this classification scheme so it can continue to be refined.
Towards Common Terminology and Definitions
Under the RCC Nanotechnology Work Plan deliverables, the Canada/US Programs were asked to consider approaches to develop common terminology and definitions for nanomaterials. It has been agreed that any terminology and nomenclature should not be developed in isolation within Canada and the US. After discussions with stakeholders at the March 20, 2013 RCC Nanotechnology Initiative Workshop7 it was concluded that the RCC should collaborate with the International Organization for Standardization (ISO) Technical Committee 229 Nanotechnologies which is developing international standards for various nanomaterial-specific functions including test methodologies, specifications for reference materials and terminology and nomenclature. The ISO has already developed and published several documents on terminology for nanomaterials, and both the Canadian and US Programs have actively participated in the ISO committee since its inception. Because of the formation of the RCC, additional mechanisms will be considered to ensure that Canada/US needs for terminology and definitions are provided to ISO. For nomenclature, the Canada/US Programs are also actively working within ISO as part of the ISO and International Union of Pure and Applied Chemistry (IUPAC) joint project on developing nomenclature for classes of nanomaterials. The two countries will consider how best to implement the outputs of these international standard committees into their respective regulatory frameworks.
Towards Nanomaterials of Potential Concern/No-Concern
As part of the RCC Work Element 2 deliverables, the Canada/US Programs were asked to determine whether they could move towards the development of classes of nanomaterials of potential concern/no-concern, as has been done for many traditional chemicals. By developing a classification scheme under the RCC, the Canada/US Programs have taken a first step towards identifying which nanomaterials they consider to be sufficiently different than their non-nano counterparts to be of concern, and which therefore may need a closer examination for environmental, human health, and safety endpoints; and, those nanomaterials which can be considered as traditional chemicals for regulatory purposes, or those of no-concern. Currently, this list is used only for sorting which nanomaterials need additional nano-specific consideration and which can be considered as traditional chemicals. There are, it should be noted, exceptions to this list which will continue to be considered on a case-by-case basis. To further inform the list, hazard classification must be taken into account, as is done when concern/no-concern lists are generated for traditional chemicals.
The Canada/US Programs believe it is still early to develop a hazard-specific list of nanomaterials of concern/no-concern because of the lack of appropriate scientific information; the approach will continue to evolve as relevant scientific information is generated.
The Canada/US Programs intend to foster research and regulatory capacity in Canada and the US to help to move toward understanding which nano-properties are relevant to hazard and exposure, and how those properties affect organisms. Dialogue and harmonization activities between the Canadian and US Programs will continue post-RCC (beyond 2014) to support further refinement of the approach outlined in this paper.
The Canadian New Substances Program and the US New Chemicals Program, using input from stakeholder consultations, are proposing a classification scheme for nanomaterials based on similarities in chemical composition to support the use of analogue/read-across information in regulatory risk assessments. This is the first time regulatory programs have considered the use of a classification scheme for nanomaterials in regulatory decision-making to increase the utilization of analogue/read-across information. The Canada/US Programs are currently exploring activities to determine how this classification scheme can be incorporated into their regulatory processes. Using a classification scheme supports the utilization of an analogue/read-across approach among similar nanomaterials and will provide increased transparency, consistency and alignment between the US and Canada regulatory approaches for stakeholders.
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