Genetic Toxicology - Mammalian Cell Mutagenicity

Study Information
Study Attribute	Value
CEBS Accession Number:	002-02934-0016-0000-7
Chemical Name:	Tribromomethane
CASRN:	75-25-2
NTP Study Type:	Genetic Toxicology - Mammalian Cell Mutagenicity
NTP Study ID:	701597
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: Inconclusive
		Conc. ug/mL	Cloning Efficiency	Relative Total Growth	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
Vehicle Control	Ethanol	0	61	82	95	52	53
			60	105	109	61
			66	110	111	56
			67	104	91	45
Test Chemical	Tribromomethane	50	87	140	65	25	25
			106	100	102	32
			86	160	49	19
		75	64	128	92	48	34
			93	110	77	28
			73	146	57	26
		100	100	113	101	34	39
			66	103	101	51
			115	109	114	33
		150	79	110	96	40	47
			88	77	118	45
			68	111	111	55
		200	82	80	124	50	43
			83	83	110	44
			95	72	102	36
		250	78	88	100	43	85*
			53	8	223	140
			70	46	149	71
Positive Control	Methyl Methane Sulfonate	5	90	100	717	265	274*
			90	82	685	255
			72	101	653	304

Nonactivation Trial: 2 Experiment Call: Positive
		Conc. ug/mL	Cloning Efficiency	Relative Total Growth	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
Vehicle Control	Ethanol	0	65	117	73	37	41
			82	117	109	44
			70	82	83	40
			64	84	79	41
Test Chemical	Tribromomethane	25	66	125	58	30	40
			73	108	82	37
			76	103	119	52
		50	67	144	89	44	43
			69	130	76	37
			68	94	100	49
		100	74	100	111	50	47
			71	100	102	48
			86	97	113	44
		175	57	22	168	99	101*
			69	43	234	114
			74	41	201	91
		200					79*
			88	52	189	71
			68	32	178	87
		250	60	21	174	97


		300


Positive Control	Methyl Methane Sulfonate	5	55	36	410	249	229*
			65	79	439	224
			68	85	437	213

Nonactivation Trial: 3 Experiment Call: Positive
		Conc. ug/mL	Cloning Efficiency	Relative Total Growth	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
Vehicle Control	Ethanol	0	86	99	76	30	26
			83	101	63	25
			74	90	62	28
			101	111	69	23
Test Chemical	Tribromomethane	100	90#	50	101	37	33
			100	58	84	28
			62	39	65	35
		150	87	36	36	14	25
			80	49	59	25
			84	39	90	36
		175	63	29	72	38	34
			124r	54	14	4
			63	17	57	30
		200	79	20	145	61	54*
			78	15	127	54
			91	17	129	47
		225	82	8	120	49	45*
			78	15	50	21
			74	14	146	66
		250					32
			80	9	126	52
			63	5	22	12
		300


Positive Control	Methyl Methane Sulfonate	5	46	48	250	181	196*
Positive Control			51	38	325	211	196*

Induced S9 Trial: 1 Experiment Call: Equivocal
		Conc. ug/mL	Cloning Efficiency	Relative Total Growth	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
Vehicle Control	Ethanol	0	72	103	196	91	98
			61	120	163	89
			51	116	155	102
			52	62	170	109
Test Chemical	Tribromomethane	6.25	52	52	194	125	126
			58	50	249	143
			59	60	197	112
		12.5	67	25	280	139	133
			49	29	218	147
			68	29	229	113
		25	49	10	249	171	149*
			46	9	191	138
			62	11	255	137
		50

		100


Positive Control	3-Methylcholanthrene	2.5	37	6	617	553	688*
Positive Control			18	2	436	823	688*

Induced S9 Trial: 2 Experiment Call: Negative
		Conc. ug/mL	Cloning Efficiency	Relative Total Growth	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
Vehicle Control	Ethanol	0	80	114	165	69	79
			89	92	210	79
			91	101	223	82
			81	93	215	88
Test Chemical	Tribromomethane	2.5	60	64	124	69	61
			72	85	106	49
			73	61	138	63
		5	69	45	187	90	68
			82	45	130	53
			66	53	121	62
		10	55	27	157	96	108
			64	30	256	134
			51	23	142	94
		25	47	5	234	165	122*
			64	10	213	111
			66	5	176	89
Positive Control	3-Methylcholanthrene	2.5	43	24	789	612	736*
			29	11	677	765
			44	13	1084	831

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