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Aromatic Azo- and Benzidine-based Substance Grouping
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The 
Aromatic azo- and benzidine-based substances are among those identified as priorities for action through the categorization process based on concerns for ecological and/or human health. Some of the substances within this substance grouping may break down to certain aromatic amines or benzidines due to the potential cleavage of the azo bonds within the molecules. Those substances have been identified by other jurisdictions as a concern due to potential release of aromatic amines or benzidines that are known or are likely to be carcinogenic or genotoxic. Some of the substances in this substance grouping are known to be or may be found in imported consumer products in Canada (for example, clothing, leather products, cosmetic and personal care products).
Subgrouping Approach
To address substances in this grouping, the Government of Canada has developed a subgrouping approach for approximately 360 aromatic azo- and benzidine-based substances based on structural similarities, physical-chemical properties, common functional uses and applications. The subgrouping approach has undergone a series of consultations including external peer reviews and a multi-stakeholder technical consultation meeting held in March 2012 in Ottawa, Canada. A record of this meeting can be found in the Meeting Summary Report on Multi-stakeholder Consultation on the Proposed Subgrouping Approach of the Aromatic Azo- and Benzidine based Substances.
Chemical Categories
Under this subgrouping approach, the majority of the substances are first divided into two chemical categories based on the chemical structure of the substances: Chemical Category I: Aromatic azo-based substances and Chemical Category II: Benzidine-based substances.
Application Classes
Within each chemical category, substances are further divided based on their "application classes". Application classes of substances are considered to be highly related to their physical-chemical properties and potential commercial uses. Application classes identified for the substances in this substance grouping are: pigments, solvent dyes, disperse dyes, acid dyes, direct dyes, reactive dyes, basic dyes, mordant dyes, and food dyes. There are some substances which do not have identifiable application classes which are placed into the application class "unknowns".
Subgroups
In Chemical Category I: Aromatic azo-based substances, each application class is designated as a subgroup, while Chemical Category II: Benzidine-based substances is divided into two subgroups: Benzidine-based pigments and Benzidine-based dyes. Substances within each subgroup may further be divided based on more detailed structural similarities. Limited scientific information is available for many of the substances in this grouping and identification of structurally related substances supports use of structure-activity relationship approaches (in other words, read-across) when conducting screening assessments.
In addition, there are 23 aromatic amines including 5 benzidine derivatives in this substance grouping that do not belong to any subgroups. These substances will be addressed individually or with their corresponding aromatic azo- or benzidine-based substances.
| Subgroup (number of substances) |
Chemical Category | Application Class |
|---|---|---|
| Monoazo pigments (33) |
I. Aromatic azo-based substances | Pigments |
| Azo Solvent dyes (22) |
Solvent dyes | |
| Azo Disperse dyes (73) |
Disperse dyes | |
| Azo Acid dyes (52) |
Acid dyes | |
| Azo Direct dyes (61) |
Direct dyes | |
| Azo Reactive dyes (8) |
Reactive dyes | |
| Azo Basic dyes (33) |
Basic dyes | |
| Azo Mordant dyes (2) |
Mordant dyes | |
| Food dyes (1) |
Food dyes | |
| Unknowns (4) |
Unknowns | |
| Benzidine-based pigments (7) |
II. Benzidine-based substances | Pigments |
| Benzidine-based dyes (39) |
Acid dyes Direct dyes Basic dyes Unknowns |
Draft Technical Background Document
The Draft Technical Background Document outlines the subgrouping approach and summarizes overarching technical knowledge on this substance grouping. This technical information will inform conduct of screening assessments moving forward.
The Government of Canada is soliciting comments on this document during a 60-day public comment period, ending September 12, 2012. Interested parties are encouraged to provide comments and suggestions to the Substances Management Information Line, indicating on the envelope or subject line "Draft Technical Background Document on the Aromatic Azo- and Benzidine-based Substance Grouping". The comments received during the 60-day public comment period will be considered in the Final Technical Background Document, anticipated for release in winter 2012/2013.
Timelines
Publication of draft screening assessment reports have been scheduled in sequence while the publication of final screening assessment reports have been scheduled to occur by early 2015. Given the scope of the Aromatic Azo- and Benzidine-based Substance Grouping, aligned publication of the final screening assessment reports will be considered where appropriate to support consistent decision-making across subgroups and to ensure coordinated risk management, as required, across the substance grouping. Follow-up information-gathering to inform risk management actions may be conducted in 2014/2015 if it is determined to be required.
Background
As part of the Chemicals Management Plan (CMP), the Government of Canada has committed to addressing approximately 4,300 substances prioritized through the categorization process by 2020. To date, some of these substances have been or are being addressed through the Challenge, the Petroleum Sector Stream Approach and other initiatives.
Of the list of priorities from categorization, a number of substances still remain to be addressed. Therefore, in June 2010, the Government of Canada published a Notice of intent to address 360 Aromatic azo- and benzidine-based substances in the Canada Gazette, Part I: Vol. 144, No. 23 - June 5, 2010 ( PDF Version - 1,170 K).
The Notice of intent indicates that the Government of Canada plans to assess the potential health and ecological risks of these substances. If, through the assessment process, it is determined that any of these substances are considered harmful to human health or the environment, then management action would be considered for those substances where appropriate.
Public comments on the Notice of intent were received through the 60-day public comment period. The Government of Canada has considered the comments received and a Summary of the Main Public Comments Received on the Notice of Intent and Government Response is available.
In December 2011, a Notice was issued in the Canada Gazette, Part I: Vol.145, No.51 - December 17, 2011 ( PDF Version - 5 372 K) under section 71 of the Canadian Environmental Protection Act, 1999 (CEPA 1999). This Notice applies to a Subset of the Aromatic Azo- and Benzidine-based Substances covered in this initiative.
The information collected from this section 71 Notice will inform the risk assessment and, if necessary, risk management for these substances. Information provided to Environment Canada and Health Canada under previous initiatives will also be taken into consideration.
If you have questions or comments, please Contact us. Indicate on the envelope or subject line "CMP Aromatic Azo- and Benzidine-based Substance Grouping".
