40 CFR 721.1660 - Benzidine-based chemical substances.

Regulations last checked for updates: Feb 16, 2025

Title 40 - Protection of Environment last revised: Nov 16, 2025

View all text of Subpart E [§ 721.225 - § 721.11893]

§ 721.1660 - Benzidine-based chemical substances.

(a) Chemical substances and significant new uses subject to reporting. (1) The benzidine-based chemical substances listed in Table 1 and Table 2 of this section are subject to reporting under this section for the significant new uses described in paragraph (a)(2) of this section.

Table 1—Benzidine-Based Chemical Substances

CAS or accession No.	C.I. name	C.I. No.	Chemical name
117-33-9	Not available	Not available	1,3-Naphthalenedisulfonic acid, 7-hydroxy-8-[2-[4'-[2-(4-hydroxyphenyl)diazenyl][1,1'-biphenyl]-4-yl]diazenyl]-
65150-87-0	Not available	Not available	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)
68214-82-4	Direct Navy BH	22590	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)
72379-45-4	Not available	Not available	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)-
Accession No. 21808 CAS No. CBI (NA)	CBI	CBI	2,7-Naphthalenedisulfonic acid, 4-amino-5- hydroxy [[[(substituted phenylamino)] substituted phenylazo] diphenyl]azo-, phenylazo-, disodium salt. (generic name)
Accession No. 24921 CAS No.	CBI	CBI	4-(Substituted naphthalenyl )azo diphenylyl azo-substituted carbopolycycle azo benzenesulfonic acid, sodium salt. (generic name)
Accession No. 26256 CAS No. CBI (NA)	CBI	CBI	4-(Substituted phenyl)azo biphenylyl azo- substituted carbopolycycloazo benzenesulfonic acid, sodium salt. (generic name)
Accession No. 26267 CAS No. CBI (NA)	CBI	CBI	4-(Substituted phenyl)azo biphenylyl azo - substituted carbopolycycle azo benzenesulfonic acid, sodium salt. (generic name)
Accession No. 26701 CAS No. CBI (NA)	CBI	CBI	Phenylazoaminohydroxynaphthalenylazobiphenylazo substituted benzene sodium sulfonate. (generic name).

Table 2—Benzidine-Based Chemical Substances

CAS No.	C.I. name	C.I. No.	Chemical name
92-87-5	Benzidine	Not available	[1,1′-Biphenyl]-4,4′-diamine.
531-85-1	Benzidine · 2HCl	Not available	[1,1′-Biphenyl]-4,4′-diamine, dihydrochloride.
573-58-0	C.I. Direct Red 28	22120	1- Naphthalenesulfonic acid, 3,3′-[[1,1′-biphenyl]-4,4′-diylbis(azo)]bis[4-amino-, disodium salt.
1937-37-7	C.I. Direct Black 38	30235	2,7-Naphthalenedisulfonic acid, 4-amino-3-[[4′-[(2,4-diaminophenyl) azo][1,1′-biphenyl]-4- yl]azo]-5-hydroxy-6-(phenylazo)-, disodium salt.
2302-97-8	C.I. Direct Red 44	22500	1-Naphthalenesulfonic acid, 8,8′-[[1,1′-biphenyl]-4,4′-diylbis(azo)]bis[7-hydroxy-, disodium salt.
2429-73-4	C.I. Direct Blue 2	22590	2,7-Naphthalenedisulfonic acid, 5-amino-3-[[4′-[(7-amino-1-hydroxy-3-sulfo-2-naphthalenyl)azo][1,1′-biphenyl]-4-yl]azo]-4-hydroxy-, trisodium salt.
2429-79-0	C.I. Direct Orange 8	22130	Benzoic acid, 5-[[4′-[(1-amino-4-sulfo-2-naphthalenyl) azo][1,1′-biphenyl]-4-yl]azo]-2- hydroxy-, disodium salt.
2429-81-4	C.I. Direct Brown 31	35660	Benzoic acid, 5-[[4′-[[2,6-diamino-3-[[8-hydroxy-3,6-disulfo-7-[(4-sulfo-1-naphthalenyl)azo]-2- naphthalenyl]azo]-5-methylphenyl]azo][1,1′- biphenyl]-4-yl]azo]-2-hydroxy-, tetrasodium salt.
2429-82-5	C.I. Direct Brown 2	22311	Benzoic acid, 5-[[4′-[(7-amino-1-hydroxy-3-sulfo-2-naphthalenyl) azo][1,1′-biphenyl]-4-yl]azo]-2-hydroxy-, disodium salt.
2429-83-6	Direct Black 4	30245	2,7-Naphthalenedisulfonic acid, 4-amino-3-[[4′-[(2,4-diamino-5-methylphenyl)azo][1,1′-biphenyl]-4-yl]azo] -5-hydroxy-6-(phenylazo)-, disodium salt.
2429-84-7	C.I. Direct Red 1	22310	Benzoic acid, 5-[[4′-[(2-amino-8-hydroxy-6-sulfo-1-naphthalenyl)azo][1,1′-biphenyl]-4-yl]azo]-2-hydroxy-, disodium salt.
2586-58-5	C.I. Direct Brown 1:2	30110	Benzoic acid, 5-[[4′-[[2,6-diamino-3-methyl-5-[(4-sulfophenyl)azo]phenyl]azo][1,1′-biphenyl]-4- yl]azo]-2-hydroxy-, disodium salt.
2602-46-2	C.I. Direct Blue 6	22610	2,7-Naphthalenedisulfonic acid, 3,3′-[[1,1′-biphenyl]-4,4′-diylbis(azo)]bis[5-amino-4-hydroxy-, tetrasodium salt.
2893-80-3	C.I. Direct Brown 6	30140	Benzoic acid, 5-[[4′-[[2,4-dihydroxy-3-[(4-sulfophenyl) azo]phenyl]azo][1,1′-biphenyl]-4- yl]azo]-2-hydroxy-, disodium salt.
3530-19-6	C.I. Direct Red 37	22240	1,3-Naphthalenedisulfonic acid, 8-[[4′-[(4-ethoxyphenyl)azo][1,1′-biphenyl]-4-yl]azo]-7-hydroxy-, disodium salt
3567-65-5	C.I. Acid Red 85	22245	1,3-Naphthalenedisulfonic acid, 7-hydroxy-8-[[4′-[[4-[[(4-methylphenyl)sulfonyl]oxy]phenyl]azo][1,1′-biphenyl]-4-yl]azo]-, disodium salt.
3626-28-6	C.I. Direct Green 1	30280	2,7-Naphthalenedisulfonic acid, 4-amino-5-hydroxy-3-[[4′-[(4-hydroxyphenyl)azo][1,1′- biphenyl]-4- yl]azo]-6-(phenylazo)-, disodium salt.
3811-71-0	C.I. Direct Brown 1	30045	Benzoic acid, 5-[[4′-[[2,4-diamino-5-[(4-sulfophenyl) azo]phenyl]azo][1,1′ biphenyl]-4- yl]azo]-2-hydroxy-, disodium salt.
4335-09-5	C.I. Direct Green 6	30295	2,7-Naphthalenedisulfonic acid, 4-amino-5-hydroxy-6-[[4′-[(4-hydroxyphenyl)azo][1,1′-biphenyl]-4- yl]azo]-3-[(4-nitrophenyl)azo]-, disodium salt.
6358-80-1	C.I. Acid Black 94	30336	2,7-Naphthalenedisulfonic acid, 4-amino-5-hydroxy-3-[[4′-[[4-hydroxy-2-[(2- methylphenyl)amino]phenyl]azo] [1,1′- biphenyl]-4-yl]azo]-6-[(4-sulfophenyl) azo]-, trisodium salt.
6360-29-8	C.I. Direct Brown 27	31725	Benzoic acid, 5-[[4′-[[4-[(4-amino-7-sulfo-1-naphthalenyl)azo]-6-sulfo-1-naphthalenyl]azo][1,1′-biphenyl]-4-yl] azo]-2- hydroxy-, trisodium salt.
6360-54-9	C.I. Direct Brown 154	30120	Benzoic acid, 5-[[4′-[[2,6-diamino-3-methyl-5-[(4-sulfophenyl)azo]phenyl] azo][1,1′-biphenyl]-4-yl]azo]-2- hydroxy-3-methyl-, disodium salt.
8014-91-3	C.I. Direct Brown 74	36300	Benzoic acid, 3,3′-[(3,7-disulfo-1,5-naphthalenediyl)bis [azo(6-hydroxy-3,1-phenylene)azo[6(or7)-sulfo-4,1-naphthalenediyl]azo[1,1′-biphenyl]-4,4′-diylazo]]bis[6-hydroxy-, hexasodium salt.
16071-86-6	C.I. Direct Brown 95	30145	Cuprate(2-), [5-[[4′-[[2,6-dihydroxy-3-[(2-hydroxy-5-sulfophenyl)azo]phenyl] azo][1,1′- biphenyl]-4-yl]azo]-2-hydroxybenzoato(4-)]-, disodium salt.

(2) The significant new uses are:

(i) For each of the chemical substances listed in Table 2 of this section, any use other than 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, additionally for Colour Index (C.I.) Direct Red 28 (Congo Red) (CAS No. 573-58-0), an indicator dye.

(ii) For the chemical substances listed in Table 1 of this section: Any use.

(b) Specific requirements. The provisions of subpart A of this part apply to this section except as modified by this paragraph (b).

(1) Revocation of certain notification exemptions. The provisions of § 721.45(f) do not apply to this section. A person who imports or processes a chemical substance identified in paragraph (a)(1) of this section as part of an article for a significant new use described in paragraph (a)(2) of this section is not exempt from submitting a significant new use notice.

(2) [Reserved]

[79 FR 77909, Dec. 29, 2014]

authority: 15 U.S.C. 2604,2607,and

source: 49 FR 35018, Sept. 5, 1984, unless otherwise noted.

cite as: 40 CFR 721.1660