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Assessing and Managing Chemicals under TSCA

Fact Sheet: Benzidine-Based Chemical Substances

Q1. What are benzidine-based chemical substances?

Benzidine and its related chemical substances are used to manufacture dyes. Benzidine-based dyes are used in the production of textiles, paints, printing inks, paper, and pharmaceuticals. They are also used as reagents and biological stains in laboratories, and have more recent uses in laser, liquid crystal displays, ink-jet printers, and electro-optical devices.

Q2. What action is EPA taking?

EPA is issuing a Significant New Use Rule, also known as a SNUR, under the Toxic Substances Control Act (TSCA). This SNUR requires manufacturers (including importers) and processors of nine benzidene-based chemical substances to notify EPA at least 90 days before starting or resuming new uses of these chemicals in any products, except for use certain limited laboratory uses. This notification allows EPA the opportunity to evaluate the intended use and, if necessary, to prohibit or limit that activity.

This SNUR amends a preexisting SNUR by adding the following nine chemical substances:

  1. 1,3-Naphthalenedisulfonic acid, 7-hydroxy-8-[2-[4'-[2-(4-hydroxyphenyl)diazenyl][1,1'- biphenyl]-4-yl]diazenyl]-
  2. 1,3,6-Naphthalenetrisulfonic acid, 8-hydroxy-7-[2-[4'-[2-(2-hydroxy-1-naphthalenyl)diazenyl][1,1'-biphenyl]-4-yl]diazenyl]-, lithium salt (1:3)
  3. 2,7-Naphthalenedisulfonic acid, 5-amino-3- [2-[4'-[2-(7-amino-1-hydroxy-3-sulfo-2- naphthalenyl)diazenyl][1,1'-biphenyl]-4- yl]diazenyl]-4-hydroxy-, sodium salt (1:2)
  4. 2,7-Naphthalenedisulfonic acid, 4-amino-5-hydroxy-3-[2-[4'-[2-[2-hydroxy-4-[(2- methylphenyl)amino] phenyl]diazenyl][1,1'- biphenyl]-4-yl]diazenyl]-6-(2- phenyldiazenyl)-
  5. 2,7-Naphthalenedisulfonic acid, 4-amino-5- hydroxy [[[(substituted phenylamino)] substituted phenylazo] diphenyl]azo-, phenylazo-, disodium salt. (generic name)
  6. 4-(Substituted naphthalenyl)azo diphenylyl azo-substituted carbopolycycle azo benzenesulfonic acid, sodium salt. (generic name)
  7. 4-(Substituted phenyl)azo biphenylyl azo- substituted carbopolycycloazo benzenesulfonic acid, sodium salt. (generic name)
  8. 4-(Substituted phenyl)azo biphenylyl azo - substituted carbopolycycle azo benzenesulfonic acid, sodium salt. (generic name)
  9. Phenylazoaminohydroxynaphthalenylazobiphenylazo substituted benzene sodium sulfonate. (generic name)

Q3. Why is EPA issuing a SNUR for benzidine-based chemical substances?

Benzidine dyes can be metabolized to benzidine, which is classified as a known human carcinogen. EPA is concerned with the potential for exposure to these chemicals. This SNUR will provide EPA the opportunity to review and control, as appropriate, before any use of the nine benzidine based dyes could resume.

Q4. Why is EPA concerned about benzidine-based dyes?

Exposure to benzidine-based dyes are of concern to consumers, workers and children because benzidine dyes can be converted in the body into a chemical that is known to cause cancer. These dyes also have the potential to separate from textiles, such as clothing, that are in prolonged contact with human skin, increasing exposure risks.

Q5. How many chemicals are in the final SNUR?

The final SNUR is adding nine benzidine-based chemical substances to a preexisting SNUR. The previous SNUR already covers 24 benzidine-based chemical substances.

Q6. What products containing benzidine are available to consumers?

The nine benzidine substances covered under this SNUR are no longer in use.

There are limited ongoing uses of some benzidine substances not covered by this SNUR including use as a reagent to test for hydrogen peroxide in milk; a reagent to test for hydrogen sulfate, hydrogen cyanide and nicotine; a stain in microscopy; a reagent for detecting blood; an analytical standard; and an indicator dye.

Q7. Is there an easy way for consumers to avoid using products with benzidine based dyes?

EPA’s Safer Chemical Ingredients List (SCIL) can be helpful for consumers who want to become familiar with safer dyes and colorants. The dyes and colorants on SCIL may not be substitutes for all benzidine-based chemical substances. Product manufacturers can use the SCIL to find safer ingredients for products. Consumers can find products made without benzidine dyes on the list of DfE-labeled safer products. For more information:

Q8. What other actions is EPA taking on benzidine-based chemical substances?

EPA previously took action on 24 benzidine-based chemical substances. Read the benzidine dyes action plan (PDF).

Q9. Are importers and processors of these chemical substances as part of articles (manufactured goods) included in this SNUR?

Yes, EPA is amending the preexisting SNUR so that the notification requirement also applies to importers and processors of these chemical substance as part of articles, such as clothing.