Genetic Toxicology - Mammalian Cell Mutagenicity

Study Information
Study Attribute	Value
CEBS Accession Number:	002-01694-0014-0000-7
Chemical Name:	Benzidine dihydrochloride
CASRN:	531-85-1
NTP Study Type:	Genetic Toxicology - Mammalian Cell Mutagenicity
NTP Study ID:	018793
Study Result:	Positive

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Table Instructions and Notes:
Studies are indicated to be "Nontoxic" when the observed reductions in relative total growth did not indicate that the maximum tolerated dose was achieved.

Nonactivation Trial: 1 Experiment Call: Positive
		Conc. ug/mL	Cloning Efficiency	Relative Total Growth	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
Vehicle Control	Water	0	104	87	53	17	19
			106	115	65	20
			105	99	64	20
			124r	107	79	21
Test Chemical	Benzidine dihydrochloride	6.25	101	92	76	25	23
			99	101	61	21	23
		12.5	103	105	57	18	17
			96	107	43	15	17
		25	96	91	84	29	32*
			95	86	101	35	32*
		50	182r	119	186	34
			105#	90	147	47
		100	96	20	351	122	124*
			89	19	338	127	124*
		150

Positive Control	Ethyl Methane Sulfonate	500	92#	38	1286	468	622*
			73	27	1338	611
			50	22	1170	788

Nonactivation Trial: 2 Experiment Call: Positive
		Conc. ug/mL	Cloning Efficiency	Relative Total Growth	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
Vehicle Control	Water	0	99#	90	57	19	15
			102	116	45	15
			99	100	35	12
			101	94	39	13
Test Chemical	Benzidine dihydrochloride	12.5	103	115	41	13	16
			103	106	59	19	16
		25	100	102	54	18	17
			101	107	47	16	17
		50	87	72	75	29	30*
			102	92	96	31	30*
		75	88	46	141	53	60*
			79	38	121	51
			71	38	158	75
		100	64	4	170	89	83*
			53	4	116	73
			89	17	233	88
		125


Positive Control	Ethyl Methane Sulfonate	500	26	13	585	736	651*
			35	14	773	729
			51	30	740	488

Induced S9 Trial: 1 Experiment Call: Positive
		Conc. ug/mL	Cloning Efficiency	Relative Total Growth	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
Vehicle Control	Water	0	101	94	95	31	27
			93	94	73	26
			102	115	85	28
			99	97	73	24
Test Chemical	Benzidine dihydrochloride	6.25	102	92	80	26	30
			97#	92	96	33	30
		12.5	72	72	70	33	35
			63	71	69	37	35
		25	99#	79	120	40	37
			82	61	83	34	37
		50	79	46	185	79	75*
			62	46	134	72	75*
		100	68	29	285	139	152*
			75	29	367	164	152*
		150	69	14	579	278	261*
			72	18	526	244	261*
		200	48	5	620	429
Positive Control	3-Methylcholanthrene	5	50	16	495	333	355*
			54	22	500	309
			45#	11	565.5	424

Induced S9 Trial: 2 Experiment Call: Positive
		Conc. ug/mL	Cloning Efficiency	Relative Total Growth	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
Vehicle Control	Water	0	120r	149	265	74	75
			105	121	227	72
			86	69	218	85
			102	110	204	66
Test Chemical	Benzidine dihydrochloride	6.25	83	107	228	92
			137r	200	192	47
		12.5	111	120	246	74
			133r	175	157	39
		25	104	113	290	93	95
			107	77	316	98	95
		50	97	72	494	170	232*
			55	35	490	295	232*
		75	41	13	517	417	492*
			26	4	362	467
			26	3	470	591
Positive Control	3-Methylcholanthrene	5					250*
			16	2	104	212
			20	2	176	289

Footnotes:
Asterisks(*) indicate significant responses.
r = rejected value due to quality control criteria
# = reduced sample size because of the loss of one culture dish due to contamination