Certain solvent dyes of the Aromatic Azo and Benzidine-based substance grouping

What are they?

  • Twenty-two substances are included in this subgroup screening assessment.
  • Certain Azo Solvent Dyes are industrial chemicals. They are not expected to occur naturally in the environment.

How are they used?

  • In general, Azo Solvent Dyes are used principally in lacquers and varnishes, printing inks and stains, plastics, as well as lawn and garden care products.
  • These substances are also used to colour plastics, waxes (for example, candles), soaps, fats, oils and gasoline.
  • Some of these substances were reported to be used as dyes or as an intermediate in dyes in the textile, leather and paper industries.
  • Based on the most recent data, none of these substances is manufactured in Canada, but five of the twenty-two substances are imported into Canada.

Why did the Government of Canada assess them?

  • Certain Azo Solvent Dyes were identified as priorities for assessment as they either met the categorization criteria of the Domestic Substances List (DSL) and/or were associated with environmental or human health concerns.
  • Certain Azo Solvent Dyes were considered in either the Chemicals Management Plan (CMP) Substance Groupings Initiative and/or the Challenge to Industry. These substances were included for the screening assessment of potential risks to the environment and to human health.
  • Five substances (Solvent Red 1, Solvent Red 3, Solvent Red 23, Solvent Yellow 18 and Solvent Orange 7) included in this subgroup were previously assessed in the earlier Challenge initiative of the CMP. Results of the Challenge assessment for these five substances found that one substance (Solvent Red 23) was found harmful to human health.
  • Except for the previous Challenge conclusions on human health for Solvent Red 23 and Solvent Orange 7, which have not been updated, these five substances are included in the current ecological assessment to consider significant new information that has been identified.

How are Canadians exposed to them?

  • Exposure of the general population of Canada to these certain Azo Solvent Dyes via environmental media is not expected.
  • Canadians may be exposed to these dyes during the use of certain products available to consumers, such as cosmetics, textiles, leathers, writing ink and paper products.

How are they released into the environment?

  • Certain Azo Solvent Dyes may be released to the environment from industrial processes.
  • They are incorporated in adhesives, and in lawn and garden care products which may result in environmental releases.

What are the results of the assessment?

  • The Government of Canada has conducted a science-based evaluation of certain Azo Solvent Dyes, called a screening assessment.
  • Screening assessments address the potential for harm to the general population of Canada and the environment.
  • Results of the final screening assessment indicate that while certain Azo Solvent Dyes are expected to remain in the environment for a long time, they are not expected to accumulate in organisms.
  • Furthermore, the quantity of these substances that may be released to the environment, are below the level expected to cause harm to organisms.
  • The conclusions for Solvent Yellow 77, also known as Disperse Yellow 3 CAS RN 2832-40-8), have been deferred to the final screening assessment for Certain Azo Disperse Dyes that will be published at a later date.
  • The Government of Canada has therefore concluded that none of the Azo Solvent Dyes assessed is entering the environment at levels that constitute a danger to the environment.
  • The Government of Canada has also concluded that the Azo Solvent Dyes assessed are not harmful to human health at current levels of exposure.
  • The previous Challenge conclusion that Solvent Red 23 is harmful to human health has not been updated, and therefore remains the same. Likewise, the previous conclusion on Solvent Orange 7, which was found not harmful to human health, has also not been updated.
  • However, given that some of these substances have health effects of concern, there may be concerns if exposures were to increase in Canada.
  • Hazards related to chemicals used in the workplace should be classified accordingly under the Workplace Hazardous Materials Information System (WHMIS).

What is the Government of Canada doing?

  • The Government of Canada published the Final Screening Assessment for Certain Azo Solvent Dyes on May 28, 2016.
  • Solvent Red 23, which was previously concluded to be harmful to human health and has not been updated in this assessment, has been added to Health Canada's Cosmetic Ingredient Hotlist. The Hotlist is used to keep the cosmetic industry aware of substances that are restricted or prohibited in cosmetics. Under Canadian legislation, cosmetics that contain substances that are harmful to the user cannot be sold.
  • Given the health concerns for some of these substances, the Government will investigate options on how best to monitor changes in the use profile of these substances. Stakeholders will have the opportunity to provide feedback on a consultation document, describing potential options for information gathering or preventative actions, to be published once the assessments for all of the Aromatic Azo and Benzidine-based Substance Grouping are completed.
  • The Significant New Activity (SNAc) provisions of the Canadian Environmental Protection Act, 1999 were applied to Solvent Red 3, Solvent Yellow 18, Solvent Red 4, CAS RN 73528-78-6, and CAS RN 85392-21-8, following their initial assessment, requiring that any proposed new manufacture, import or use be subject to further assessment to determine if any new activity required further risk management consideration. However, as a result of this new assessment, it is proposed to remove the SNAc provisions on these substances.

What can Canadians do?

  • The health risks associated with a chemical depend on the hazard (its potential to cause health effects) and the dose (the amount of chemical to which you are exposed). None of the Certain Azo Solvent Dyes assessed is presently a concern for the environment or human health at current levels of exposure.
  • Canadians who may be exposed to these Certain Azo Solvent Dyes in the workplace should consult with their employer and occupational health and safety (OHS) representative about safe handling practices, applicable laws and requirements under the OHS legislation and the Workplace Hazardous Materials Information System (WHMIS).
  • As a general precaution, Canadians are reminded when using any product to carefully follow any safety warnings and directions, and to dispose of the products appropriately.
Azo Solvent Dyes Assessed by the Government of Canada
CAS RN DSL Name Colour Index Name or Common Name
60-09-3 Benzenamine, 4-(phenylazo)- Solvent Yellow 1 or p‑Aminoazobenzene
60-11-7 Benzenamine, N,N-dimethyl-4-(phenylazo)- Solvent Yellow 2
97-56-3 Benzenamine, 2-methyl-4-[(2-methylphenyl)azo]- Solvent Yellow 3
103-33-3 Diazene, diphenyl- Azobenzene
495-54-5 1,3-Benzenediamine, 4-(phenylazo)- Solvent Orange 3
2832-40-8 Acetamide, N-[4-[(2-hydroxy-5-methylphenyl)azo]phenyl]- Solvent Yellow 77
101-75-7 Benzenamine, N-phenyl-4-(phenylazo)- 4-Anilinoazobenzene
842-07-9 2-Naphthalenol, 1-(phenylazo)- Solvent Yellow 14 or Sudan I
1229-55-6 2-Naphthalenol, 1-[(2-methoxyphenyl)azo]- Solvent Red 1
2646-17-5 2-Naphthalenol, 1-[(2-methylphenyl)azo]- Solvent Orange 2
or Oil Orange SS
3118-97-6 2-Naphthalenol, 1-[(2,4-dimethylphenyl)azo]- Solvent Orange 7
5290-62-0 1-Naphthalenol, 4-[(4-nitrophenyl)azo]- Magneson II
6535-42-8 1-Naphthalenol, 4-[(4-ethoxyphenyl)azo]- Solvent Red 3
2653-64-7 2-Naphthalenol, 1-(1-naphthalenylazo)- Solvent Red 4
6407-78-9 3H-Pyrazol-3-one, 4-[(2,4-dimethylphenyl)azo]-2,4-dihydro-5-methyl-2-phenyl- Solvent Yellow 18
85-83-6 2-Naphthalenol, 1-[[2-methyl-4-[(2-methylphenyl)azo]phenyl]azo]- Solvent
Red 24 or
Sudan IV
85-86-9 2-Naphthalenol, 1-[[4-(phenylazo)phenyl]azo]- Solvent
Red 23
6368-72-5 2-Naphthalenamine, N-ethyl-1-[[4-(phenylazo)phenyl]azo]- Solvent
Red 19
21519-06-2 3H-Pyrazol-3-one, 2,4-dihydro-2-(3-hydroxyphenyl)-5-methyl-4-[[4-(phenylazo)phenyl]azo]- NA
73528-78-6 3-Pyridinecarbonitrile, 5-[[4-[(2,6-dichloro-4-nitrophenyl)azo]-2,5-dimethoxyphenyl]azo]-2,6-bis[(2-methoxyethyl)amino]-4-methyl- NA
85392-21-8 3-Pyridinecarbonitrile, 5-[[2-chloro-4-(phenylazo)phenyl]azo]-2,6-bis[(3-methoxypropyl)amino]-4-methyl- NA
73507-36-5 2-Naphthalenesulfonic acid, 7-(benzoylamino)-4-hydroxy-3-[[4-[(4-sulfophenyl)azo]phenyl]azo]-, compounds with N,N’-bis (mixed Ph and tolyl and xylyl) guanidine monohydrochloride- NA

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