Azo Acid Dyes of the Aromatic Azo and Benzidine-based substance grouping

What are they?

  • Fifty-two substances have been included in the assessment of Certain Azo Acid Dyes.
  • These Azo Acid Dyes are industrial chemicals. They are not expected to occur naturally in the environment.

How are they used?

  • The 52 Azo Acid Dyes are used primarily as colouring agents for dyeing textiles (i.e. nylon, wool and silk). They are also used in cosmetics, leather, drugs and natural health products, soaps and other cleaning compounds, paper and inks.
  • Two of the 52 Azo Acid Dyes, amaranth and tartrazine, are permitted food colouring agents used in Canada.
  • Based on the most recent data, these 52 Azo Acid Dyes are not manufactured in Canada; however, some are imported into the country.

Why did the Government of Canada assess them?

  • The 52 Azo Acid Dyes were identified as priorities for assessment based on the categorization of substances within the Domestic Substances List, and/or were considered as priority substances based on other human health concerns.
  • Furthermore, these Azo Acid Dyes were considered in the Chemicals Management Plan as part of the Substance Groupings Initiative. These substances were included for the screening assessment of potential risks to the environment and to human health.

How are Canadians exposed to them?

  • Exposure of the general population to these dyes from air, water or soil is expected to be negligible.
  • Canadians may be exposed to some of these substances during the use of certain products available to consumers, such as cosmetics, drugs and natural health products, textiles, and leather products.
  • Canadians may also be exposed to two of the 52 Azo Acid Dyes, amaranth and tartrazine, through consumption of certain foods.

How are they released into the environment?

  • The Azo Acid Dyes in this assessment may be released to the environment as a result of industrial processes.
  • Release may also occur through the use and disposal of products containing these substances.

What are the results of the assessment?

  • The Government of Canada has conducted a science-based evaluation of 52 Azo Acid 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 the 52 Azo Acid Dyes have the potential to remain in the environment for a long time, but they are not expected to accumulate in organisms.
  • Furthermore, the quantity of these substances that have the potential to be released to the environment is below the level expected to cause harm to organisms.
  • The Government of Canada has therefore concluded that the 52 Azo Acid Dyes are not entering the environment at levels that constitute a danger to the environment.
  • The Government of Canada has also concluded that the 52 Azo Acid Dyes are not harmful to human health at current levels of exposure.
  • However, given that some of these substances have health effects of concern based on potential carcinogenicity, there may be additional concern if levels were to increase in certain products available to consumers 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 Acid Dyes on June 18, 2016.
  • Based on the conclusion of the final screening assessment, the Government of Canada proposes that no further action be taken on the Azo Acid Dyes in this assessment.
  • The Government of Canada is working on developing proposed updates to the existing food additive provisions for amaranth that are set out in the List of Permitted Colouring Agents and which apply to foods sold in Canada. The updates will better align the food additive provisions with current food uses and ensure that intake of amaranth from its food additive uses remains within acceptable levels.
  • Although not a concern at current levels of exposure, given the health concerns for some of these substances in certain products available to consumers, 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 assessments for all of the Aromatic Azo and Benzidine-based Substance Grouping are completed.
  • In addition, Significant New Activity (SNAc) provisions were applied to 6 Azo Acid Dye substances, following their initial assessment (Canada 2008). These provisions require 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, as they are no longer considered to have health or ecological effects of concern.

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). The Azo Acid Dyes in this assessment are not a concern for the environment or human health at current levels of exposure.
  • Canadians who may be exposed to these substances in the workplace should consult with their employer and 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).
  • 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 Acid Dyes assessed by the Government of Canada (52 substances)
CAS RN DSL Name Colour Index name or common name
587-98-4 Benzenesulfonic acid, 3-[[4-(phenylamino)phenyl]azo]-, monosodium salt Metanil Yellow
633-96-5 Benzenesulfonic acid, 4-[(2-hydroxy-1-naphthalenyl)azo]-, monosodium salt Orange II
915-67-3 2,7-Naphthalenedisulfonic acid, 3-hydroxy-4-[(4-sulfo-1-naphthalenyl)azo]-, trisodium salt Amaranth
1934-21-0 1H-Pyrazole-3-carboxylic acid, 4,5-dihydro-5-oxo-1-(4-sulfophenyl)-4-[(4-sulfophenyl)azo]-, trisodium salt Tartrazine
2611-82-7 1,3-Naphthalenedisulfonic acid, 7-hydroxy-8-[(4-sulfo-1-naphthalenyl)azo]-, trisodium salt New Coccine
3071-73-6 1-Naphthalenesulfonic acid, 8-(phenylamino)-5-[[4-[(5-sulfo-1-naphthalenyl)azo]-1-naphthalenyl]azo]-, disodium salt Acid Black 24
3351-05-1 1-Naphthalenesulfonic acid, 8-(phenylamino)-5-[[4-[(3-sulfophenyl)azo]-1-naphthalenyl]azo]-, disodium salt Acid Blue 113
3761-53-3 2,7-Naphthalenedisulfonic acid, 4-[(2,4-dimethylphenyl)azo]-3-hydroxy-, disodium salt Ponceau MX
6262-07-3 2-Naphthalenesulfonic acid, 6-hydroxy-5-[[4-[[4-(phenylamino)-3-sulfophenyl]azo]-1-naphthalenyl]azo]-, disodium salt Acid Black 26
6507-77-3 1,3-Naphthalenedisulfonic acid, 7-hydroxy-8-[[4-[1-[4-[(4-hydroxyphenyl)azo]phenyl]cyclohexyl]phenyl]azo]-, disodium salt Acid Orange 33
15792-43-5 2,7-Naphthalenedisulfonic acid, 5-(acetylamino)-3-[(4-dodecylphenyl)azo]-4-hydroxy-, disodium salt Acid Red 138
25317-22-0 1-Naphthalenesulfonic acid, 3-[[4-(benzoylethylamino)-2-methylphenyl]azo]-4-hydroxy- Acid Red 6
29706-48-7 Benzenesulfonic acid, 3-[[[4-(2-benzothiazolylazo)-3-methylphenyl]ethylamino]methyl]- Not applicable
35342-16-6 7-Benzothiazolesulfonic acid, 2-[4-[(hexahydro-2,4,6-trioxo-5-pyrimidinyl)azo]phenyl]-6-methyl-, monolithium salt Not applicable
51988-24-0 Benzenesulfonic acid, 3-[[4-[(4-hydroxy-3-methylphenyl)azo]-3-methoxyphenyl]azo]-, monolithium salt Not applicable
52236-73-4 Benzenesulfonic acid, 4-[(5-amino-3-methyl-1-phenyl-1H-pyrazol-4-yl)azo]-2,5-dichloro-, monolithium salt Not applicable
62133-79-3 2-Naphthalenesulfonic acid, 5-[[4-[ethyl[(3-sulfophenyl)methyl]amino]phenyl]azo]-8-(phenylazo)-, disodium salt Not applicable
62133-80-6 2-Naphthalenesulfonic acid, 8-[[4-[ethyl[(3-sulfophenyl)methyl]amino]phenyl]azo]-5-(phenylazo)-, disodium salt Not applicable
67892-55-1 1-Naphthalenesulfonic acid, 5-[[4-[(2-chlorophenyl)azo]-6(or 7)-sulfo-1-naphthalenyl]azo]-8-(phenylamino)-, disodium salt Not applicable
68155-63-5 2,7-Naphthalenedisulfonic acid, 5-[[2,4-dihydroxy-5-[(4-nitrophenyl)azo]phenyl]azo]-4-hydroxy-3-[(2-hydroxy-3,5-dinitrophenyl)azo]-, disodium salt Not applicable
68555-86-2 Benzenesulfonic acid, 4-[[5-methoxy-4-[(4-methoxyphenyl)azo]-2-methylphenyl]azo]-, sodium salt Acid Orange 156
70210-05-8 2,7-Naphthalenedisulfonic acid, 3-[[2,4-bis(2-methylphenoxy)phenyl]azo]-4-hydroxy-5-[[(4-methylphenyl)sulfonyl]amino]-, disodium salt Not applicable
70210-06-9 Benzenesulfonic acid, 3-[[ethyl[4-[[4-[(3-sulfophenyl)azo]-1-naphthalenyl]azo]phenyl]amino]methyl]-, disodium salt Not applicable
70210-25-2 2,7-Naphthalenedisulfonic acid, 5-[[2,4-dihydroxy-5-[(2-hydroxy-3,5-dinitrophenyl)azo]phenyl]azo]-4-hydroxy-3-[(4-nitrophenyl)azo]-, disodium salt Not applicable
70210-34-3 2,7-Naphthalenedisulfonic acid, 5-[[2,4-dihydroxy-5-[[4-[(4-nitro-2-sulfophenyl)amino]phenyl]azo]phenyl]azo]-4-hydroxy-3-[[4-[(4-nitro-2-sulfophenyl)amino]phenyl]azo]-, tetrasodium salt Not applicable
71720-89-3 2-Naphthalenesulfonic acid, 5-[[4-(4-cyclohexylphenoxy)-2-sulfophenyl]azo]-6-[(2,6-dimethylphenyl)amino]-4-hydroxy-, disodium salt Not applicable
71873-51-3 Benzenesulfonic acid, 2,5-dichloro-4-[4-[[5-[[(dodecyloxy)carbonyl]amino]-2-sulfophenyl]azo]-4,5-dihydro-3-methyl-5-oxo-1H-pyrazol-1-yl]-, disodium salt Not applicable
72496-92-5 Naphthalenesulfonic acid, 5-[[2,4-dihydroxy-5-[[4-[(4-nitro-2-sulfophenyl)amino]phenyl]azo]phenyl]azo]-8-[[4-[(4-nitro-2-sulfophenyl)amino]phenyl]azo]-, trisodium salt Not applicable
72828-67-2 1,3-Naphthalenedisulfonic acid, 7-hydroxy-8-[[4-[1-[4-[(4-hydroxyphenyl)azo]phenyl]cyclohexyl]phenyl]azo]-, potassium sodium salt Not applicable
72828-83-2 2,7-Naphthalenedisulfonic acid, 5-(benzoylamino)-3-[[2-(2-cyclohexylphenoxy)phenyl]azo]-4-hydroxy-, disodium salt Not applicable
72968-80-0 2-Naphthalenesulfonic acid, 5-[[4-[[(4-methylphenyl)sulfonyl]oxy]phenyl]azo]-8-[[4-[(4-nitro-2-sulfophenyl)amino]phenyl]azo]-, disodium salt Not applicable
72968-81-1 2-Naphthalenesulfonic acid, 8-[[4-[[(4-methylphenyl)sulfonyl]oxy]phenyl]azo]-5-[[4-[(4-nitro-2-sulfophenyl)amino]phenyl]azo]-, disodium salt Not applicable
72986-60-8 2-Naphthalenesulfonic acid, 5-[[4-[(4-nitro-2-sulfophenyl)amino]phenyl]azo]-8-[[4-[(phenylsulfonyl)oxy]phenyl]azo]-, disodium salt Not applicable
72986-61-9 2-Naphthalenesulfonic acid, 8-[[4-[(4-nitro-2-sulfophenyl)amino]phenyl]azo]-5-[[4-[(phenylsulfonyl)oxy]phenyl]azo]-, disodium salt Not applicable
75949-73-4 Benzenesulfonic acid, 4,4'-[methylenebis[4,1-phenyleneazo(4,5-dihydro-3-methyl-5-oxo-1H-pyrazole-4,1-diyl)]]bis[3-methyl-, disodium salt Not applicable
79234-36-9 2,7-Naphthalenedisulfonic acid, 5-(benzoylamino)-3-[[2-(4-cyclohexylphenoxy)phenyl]azo]-4-hydroxy-, disodium salt Not applicable
83006-48-8 Benzenesulfonic acid, 4-[4-[[3-[(ethylphenylamino)sulfonyl]-4-methylphenyl]azo]-4,5-dihydro-3-methyl-5-oxo-1H-pyrazol-1-yl]- Not applicable
83006-74-0 1-Naphthalenesulfonic acid, 8-(phenylamino)-5-[[4-[(5-sulfo-1-naphthalenyl)azo]-1-naphthalenyl]azo]-, ammonium sodium salt Not applicable
83006-77-3 1-Naphthalenesulfonic acid, 8-(phenylamino)-5-[[4-[(3-sulfophenyl)azo]-1-naphthalenyl]azo]-, ammonium sodium salt Not applicable
83027-51-4 1,7-Naphthalenedisulfonic acid, 6-[[2-(4-cyclohexylphenoxy)phenyl]azo]-4-[[(2,4-dichlorophenoxy)acetyl]amino]-5-hydroxy-, disodium salt Not applicable
83027-52-5 1,7-Naphthalenedisulfonic acid, 6-[[2-(2-cyclohexylphenoxy)phenyl]azo]-4-[[(2,4-dichlorophenoxy)acetyl]amino]-5-hydroxy-, disodium salt Not applicable
83221-60-7 1,6-Naphthalenedisulfonic acid, 4-[[4-[[1-hydroxy-6-(phenylamino)-3-sulfo-2-naphthalenyl]azo]-1-naphthalenyl]azo]-, ammonium sodium salt Not applicable
84559-92-2 2,7-Naphthalenedisulfonic acid, 3,3'-[azoxybis[(2-methoxy-4,1-phenylene)azo]]bis[4,5-dihydroxy-, tetralithium salt Not applicable
84962-50-5 Benzenesulfonic acid, 2,5-dichloro-4-[[2-(dibutylamino)-4-methyl-6-[[2-(4-sulfophenyl)ethyl]amino]-5-pyrimidinyl]azo]-, sodium salt Not applicable
85030-31-5 2,7-Naphthalenedisulfonic acid, 3-hydroxy-4-[[4-[[4-[(2-hydroxy-6-sulfo-1-naphthalenyl)azo]-2-methylphenyl]methyl]-3-methylphenyl]azo]-, sodium salt Not applicable
85136-25-0 2,7-Naphthalenedisulfonic acid, 3,3'-[azoxybis[(2-methoxy-4,1-phenylene)azo]]bis[4,5-dihydroxy-, lithium sodium salt Not applicable
85223-35-4
102616-51-3
Benzoic acid, 3,3'-methylenebis[6-[[2,4-dihydroxy-5-[(4-sulfophenyl)azo]phenyl]azo]-, sodium salt Not applicable
90218-20-5 Benzenesulfonic acid, 5-amino-2,4-dimethyl-, diazotized, coupled with diazotized 2,4-, 2,5-and 2,6-xylidine and 4-[(2,4-dihydroxyphenyl)azo]benzenesulfonic acid, sodium salts Not applicable
90432-08-9 2,7-Naphthalenedisulfonic acid, 4-amino-5-hydroxy-, diazotized, coupled with diazotized 4-nitro-1,3-benzenediamine and resorcinol, potassium sodium salts Not applicable
90459-02-2 2,7-Naphthalenedisulfonic acid, 5-amino-4-hydroxy-3-[[6-sulfo-4-[(4-sulfo-1-naphthalenyl)azo]-1-naphthalenyl]azo]-, diazotized, coupled with diazotized 4-nitrobenzenamine and resorcinol, potassium sodium salts Not applicable
106028-58-4 2,7-Naphthalenedisulfonic acid, 6-amino-4-hydroxy-3-[[7-sulfo-4-[(4-sulfophenyl)azo]-1-naphtalenyl]azo]-, tetralithium salt Not applicable
114910-04-2 1-Naphthalenediazonium, 4-[[4-[(4-nitro-2-sulfophenyl)amino]phenyl]azo]-6-sulfo-, chloride, reaction products with formaldehyde and salicylic acid, ammonium sodium salts Not applicable
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