Genetic Toxicology - Mammalian Cell Mutagenicity

Study Information
Study Attribute	Value
CEBS Accession Number:	002-01342-0012-0000-5
Chemical Name:	2-Mercaptobenzothiazole
CASRN:	149-30-4
NTP Study Type:	Genetic Toxicology - Mammalian Cell Mutagenicity
NTP Study ID:	920542
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: Negative
		Conc. ug/mL	Cloning Efficiency	Relative Total Growth	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
Vehicle Control	Ethanol	0	93	110	69	25	23
			81	97	60	25
			95	95	52	18
			97	98	65	22
Test Chemical	2-Mercaptobenzothiazole	30	77	77	61	26	27
			81	87	75	31
			95	96	68	24
		40	72	70	66	31	28
			90	81	61	23
			66	72	59	30
		50	70#	52	83	39	32
			92	62	66	24	32
		60	91	60	44	16	21
			89	71	56	21
			77	59	62	27
		80	92	55	90	32	33
			79	40	90	38
			77	58	65	28
		100	70	33	93	44	34*
			78	33	66	28
			82	35	73	30
		150


Positive Control	Methyl Methane Sulfonate	5	44	25	222	168	197*
			35	19	281	266
			62	40	290	157

Nonactivation Trial: 2 Experiment Call: Rejected
		Conc. ug/mL	Cloning Efficiency	Relative Total Growth	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
Vehicle Control	Ethanol	0	101	116	36	12	14
			107	86	71	22
			73#	83	28	13
			117	115	32	9
Test Chemical	2-Mercaptobenzothiazole	40	57	33	70	41	34*
			64	48	66	34
			73	43	57	26
		50	85	37	76	30	26*
			67	43	46	23
			54	23	42	26
		60	59#	41	50	28	25*
			66	44	48	24
			88	15	62	24
		80	72	20	62	29	19
			78	22	27	12
			73	40	37	17
		100	40	5	59	49	26*
			84	15	35	14
			101	15	46	15
		120					25*
			52	5	53	34
			95	14	43	15
		160


Positive Control	Methyl Methane Sulfonate	5	100	94	130	43	40*
			86	83	94	36
			86	95	104	40

Nonactivation Trial: 3 Experiment Call: Negative
		Conc. ug/mL	Cloning Efficiency	Relative Total Growth	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
Vehicle Control	Ethanol	0	99	103	84	28	26
			117	105	91	26
			97	99	69	24
			101	94	78	26
Test Chemical	2-Mercaptobenzothiazole	40	101	30	59	20	26
			92	42	71	26
			59	7	60	34
		60	69	17	39	19	19
			98#	24	77	26
			107	13	39	12
		80	69	11	73	35	36
			113	13	157	46
			87	19	71	27
		100	66	6	69	35	34
			60	6	60	34

		120

		140


Positive Control	Methyl Methane Sulfonate	5	54	28	634	394	393*
			54	30	690	426
			62	35	664	359

Induced S9 Trial: 1 Experiment Call: Rejected
		Conc. ug/mL	Cloning Efficiency	Relative Total Growth	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
Vehicle Control	Ethanol	0	67	95	204	101	79
			100#	111	218	73
			83#	91	180	72
			87	103	184	70
Test Chemical	2-Mercaptobenzothiazole	1.25	72	65	147	68	66
			59	63	75	42
			73	68	190	87
		2.5	72	73	105	49	52
			72	66	114	53
			58	70	92	53
		5	113	49	134	40	38
			85	62	68	27
			72	59	101	47
		7.5	81	32	196	80	73
			92	38	201	73
			93	30	181	65
		10	85	22	244	95	87
			82	25	233	95
			93	25	203	73
		15	73	10	230	106	130*
			87	16	277	106
			77	10	415	179
Positive Control	3-Methylcholanthrene	2.5	22	8	411	632	537*
			29	10	509	588
			57	39	665	391

Induced S9 Trial: 2 Experiment Call: Positive
		Conc. ug/mL	Cloning Efficiency	Relative Total Growth	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
Vehicle Control	Ethanol	0	84	102	90	36	35
			123r	129	187	51
			75#	89	76	34
			84#	110	93	37
Test Chemical	2-Mercaptobenzothiazole	5	91	106	158	58	66*
			75	75	163	72
			71	74	146	68
		6	79	79	141	60	69*
			77	58	137	60
			64	42	169	89
		8	66#	52	125	63	58*
			81	40	123	51
			96	53	172	60
		10	101	40	255	84	104*
			67	33	263	132
			81	34	233	96
		12	76	33	188	82	100*
			90	34	234	87
			59#	20	233	131
		16	64	26	213	111	69*
			63	19	30	16
			78	19	189	81
Positive Control	3-Methylcholanthrene	2.5	97	64	696	240	277*
			52	36	510	325
			70	38	561	267

Induced S9 Trial: 3 Experiment Call: Inconclusive
		Conc. ug/mL	Cloning Efficiency	Relative Total Growth	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
Vehicle Control	Ethanol	0	115	118	143	41	45
			71	94	124	58
			61	94	79	43
			68	94	78	38
Test Chemical	2-Mercaptobenzothiazole	5	96	93	119	41	51
			79	76	161	68
			64	80	86	45
		6	84	63	131	52	52
			106	98	169	53
			94	94	147	52
		8	105	71	144	46	50
			101	84	163	54
			72	93	110	51
		10	94	96	122	43	55
			79	63	155	66
			123r	91	123	33
		12	100	76	192	64	47
			96	77	132	46
			110	104	105	32
		16	89	59	147	55	54
			105	78	162	51
			78	52	131	56
Positive Control	3-Methylcholanthrene	2.5	114	82	639	186	178*
			111	92	499	150
			87	74	519	198

Induced S9 Trial: 4 Experiment Call: Positive
		Conc. ug/mL	Cloning Efficiency	Relative Total Growth	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
Vehicle Control	Ethanol	0	106	100	112	35	39
			101	87	112	37
			90	105	115	42
			93	109	116	42
Test Chemical	2-Mercaptobenzothiazole	4	80	65	128	53	56
			87	82	148	57
			81	66	142	58
		8	73	51	106	48	54
			75	51	128	57
			114	75	188	55
		10	74	43	147	67	56
			108	57	178	55
			80	47	115	48
		12	69	32	163	79	67*
			78	35	157	67
			64	34	104	54
		16	77	26	159	69	75*
			80	32	183	77
			90	33	211	78
		20	77	18	157	68	72*
			104	24	213	68
			82	21	197	80
Positive Control	3-Methylcholanthrene	2.5	68	49	545	267	325*
			69	38	771	375
			81	40	804	332

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