Certain Azo Disperse Dyes - information sheet

Updated February 23, 2019:

The Final Screening Assessment of Certain Azo Disperse Dyes was published on as part of the Substance Grouping Initiative of the Chemicals Management Plan (CMP). The assessment is summarized in this information sheet (formerly public summary) and has not changed. The section in this information sheet entitled "Preventive actions and reducing risk" has been revised to communicate the following update:

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  • The Government of Canada conducted a science-based evaluation of Certain Azo Disperse Dyes, called a screening assessment, to address the potential for harm to Canadians and the environment.
  • Under the Canadian Environmental Protection Act, 1999 (CEPA 1999), the risk posed by a substance is determined by considering both its hazardous properties (its potential to cause adverse human health or ecological effects) and the amount of exposure there is to people or the environment. A substance may have hazardous properties; however, the risk to human health or to the environment may be low depending upon the level of exposure.
  • As a result of the screening assessment, it was concluded that 73 of the 74 Azo Disperse Dyes are not harmful to human health or the environment. Disperse Yellow 3 was concluded to be harmful to the environment.

About these substances

  • Seventy-four substances are included in this assessment of Certain Azo Disperse Dyes. These substances were considered in the Substance Groupings Initiative of the CMP.
  • Of the 74 substances included in this assessment of Certain Azo Disperse Dyes, 1 substance (Disperse Yellow 3, also known as Solvent Yellow 77 or CAS RN 2832-40-8) was also included in the assessment of Certain Azo Solvent Dyes.
  • Disperse Yellow 3 was evaluated in this assessment of Certain Disperse Dyes due to ecological concerns when used as a disperse dye in the dyeing of textiles. Disperse Yellow 3 was evaluated in the assessment of Certain Azo Solvent Dyes for human health concerns and other uses of this dye.
  • Twenty-four Azo Disperse Dye substances included in this grouping were previously assessed during the earlier Challenge Initiative of the CMP. At that time, these substances were found not to be harmful to the environment or human health, with the exception of the substance ANMOM, which was not concluded on in the Challenge Initiative.
  • Thirty-three Azo Disperse Dyes were previously assessed in April 2008 as part of an assessment of 145 PBiT (Persistent, Bioaccumulative and inherently Eco-Toxic) substances under CEPA 1999. That assessment identified a potential ecological concern with respect to new uses for these substances.
  • Azo Disperse Dyes are man-made chemicals. They are not expected to occur naturally in the environment.
  • Azo Disperse Dyes are used primarily in the dyeing of textiles (mainly synthetic fibres).
  • On the basis of recent data, the 74 Azo Disperse Dyes are not manufactured in Canada; however, some are imported into the country.

Exposure of Canadians and the environment

  • Canadians may be exposed to 12 of these Azo Disperse Dyes as well as to Disperse Yellow 3 from textiles containing these substances. Exposure to the other substances was not expected.
  • These substances may be released to the environment during textile dye formulation and textile dyeing.

Key health and ecological effects (hazard)

  • Carcinogenicity (the ability to cause cancer) and genotoxicity (ability to adversely affect genetic material) were the important or "critical" effects considered for characterizing the risk to human health in this assessment. These effects were considered due to the potential for azo bond cleavage and release of aromatic amines with effects of concern.
  • Non-cancer effects on the spleen were also used for characterizing the risk to human health.
  • Available aquatic toxicity data for Azo Disperse Dyes indicated variable effects on different organisms. Chronic studies showed that fish and aquatic invertebrates were sensitive to Azo Disperse Dyes, particularly smaller sized dyes.

Risk assessment outcomes

  • For the 13 substances for which exposure of Canadians was expected, a comparison of levels to which Canadians can be exposed and levels associated with health effects showed that the risk to human health is low.
  • Results of the final screening assessment indicate that these Azo Disperse Dyes are expected to remain in the environment for a long time, under certain conditions, but are not expected to accumulate in organisms.
  • These 74 substances were proposed to be harmful to the environment at the draft screening assessment stage for the subgroup. New hazard information received after that publication led to a change in the ecological conclusion in the final screening assessment.
  • Eight azo disperse dyes in the assessment and an additional 17 azo disperse dyes, all with molar weights below 360 g/mol, were identified as having potential ecological effects of concern.
  • The Government of Canada published the Final Screening Assessment for Certain Azo Disperse Dyes on .

Screening assessment conclusions

  • The Government concluded that these 74 Azo Disperse Dyes (including Disperse Yellow 3) are not harmful to human health at current levels of exposure.
  • The Government also concluded that 73 of the 74 Azo Disperse Dyes are not entering the environment at levels that are harmful to the environment. It was also concluded that the remaining substance, Disperse Yellow 3 (CAS RN 2832-40-8), is entering or may enter the environment at levels that are harmful to the environment.

Preventive actions and reducing risk

  • The Government of Canada published the Proposed Risk Management Approach for Disperse Yellow 3 on March 11, 2017. The proposed risk management approach was followed by a 60-day public comment period that ended on .
    • Disperse Yellow 3 was added to Schedule 1 of CEPA 1999, also called the List of Toxic Substances.
    • Given new information received on Disperse Yellow 3 usage in Canada, the proposed risk management approach is being revisited. The new information indicates that remaining facilities still using Disperse Yellow 3 plan to stop importing and using the substance.
    • The Risk Management Approach proposed to manage the risk of Disperse Yellow 3 through a Pollution Prevention (P2) planning notice. Given that the current reported uses of Disperse Yellow 3 are likely to be phased out in the short term, a P2 planning notice is no longer considered as an option, since the preparation and implementation of P2 plans are done over many years.
    • Release Guidelines have been selected as the optimal risk management instrument to address the toxicity of Disperse Yellow 3 and the environmental concerns associated with the 25 other azo disperse dyes with molar weights below 360 g/mol.
  • Although they are not a concern at current levels of exposure, some of these Azo Disperse Dyes as well as other substances of the Aromatic Azo and Benzidine-based Substance Grouping have health or ecological effects of concern. The Government has investigated options on how best to monitor changes in the use profile of these substances.
  • Therefore, a Consultation Document on the Options for Addressing Certain Aromatic Azo and Benzidine-based Substances with Effects of Concern was published concurrently with this assessment. The document describes potential options for information gathering or preventative actions for certain Aromatic Azo and Benzidine-based Substances. Stakeholders were asked to provide feedback on the document during the 60-day public comment period that ended on May 10, 2017.
  • Significant New Activity (SNAc) provisions were previously applied to 33 Azo Disperse Dye substances. Thirty-two of these 33 substances were included in the 2008 assessment of 145 PBiT substances, and 1 substance (Disperse Orange 5) was assessed in 2009 under Batch 5 of the Challenge. These provisions require that any proposed new manufacture, import or use of the substances be subject to further assessment to determine if any new activities require further risk management consideration.
  • As a result of the Final Screening Assessment of Certain Azo Disperse Dyes, the requirements under the SNAc provisions on these 33 substances were rescinded in July 2017, as the substances are no longer considered to have ecological effects of concern. Therefore, new activities involving these substances are no longer a concern.
  • Further information and updates on risk management actions can be found in the CMP risk management actions table and the risk management activities and consultations schedule.

Related information

  • Canadians should follow any safety warnings and directions on product labels and dispose of products responsibly.
  • Canadians who may be exposed to these substances in the workplace should consult with their employer and an occupational health and safety (OHS) representative about safe handling practices, applicable laws and requirements under OHS legislation and the Workplace Hazardous Materials Information System (WHMIS).
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