Genetic Toxicology - Mammalian Cell Mutagenicity

Study Information
Study Attribute	Value
CEBS Accession Number:	002-02340-0015-0000-7
Chemical Name:	L-Ascorbic acid
CASRN:	50-81-7
NTP Study Type:	Genetic Toxicology - Mammalian Cell Mutagenicity
NTP Study ID:	802020
Study Result:	Equivocal

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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	Water	0	117	98	127	36	29
			110	104	84	25
			114	89	110	32
			102	109	63	21
Test Chemical	L-Ascorbic acid	125	72	85	41	19	28
			85	101	92	36	28
		250	57	78	89	52	35
			54	72	46	28
			76	94	59	26
		500	58	67	87	50	39
			81	86	72	30
			65	66	71	36
		750	104	77	81	26	53*
			36	34	86	80	53*
		1000	64	49	83	44	38
			66	56	44	22
			83	61	120	48
		1500	77	47	120	52	34
			96	73	79	27
			90	59	65	24
		2000


Positive Control	Methyl Methane Sulfonate	5	86	54	489	190	118*
			103	70	126	41
			93	84	342	123

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	57	89	69	40	36
			73	101	80	36
			51	95	57	37
			60	115	57	32
Test Chemical	L-Ascorbic acid	125	96	98	127	44	46
			100	114	117	39
			83	80	135	55
		250	89	109	86	32	30
			71	99	60	28
			121r	116	93	26
		500	111	69	118	36	37
			87	82	108	41
			94	96	98	35
		750	39	19	102	88	65*
			88	86	97	37
			73	52	156	71
		1000	32	35	57	59	56*
			31	51	53	57
			31	50	48	51
		1500	74	67	152	69	67*
			73	71	157	72
			72	69	128	60
		2000


Positive Control	Methyl Methane Sulfonate	5	32	26	316	334	300*
			31	29	241	258
			34	23	318	309

Nonactivation Trial: 3 Experiment Call: Positive
		Conc. ug/mL	Cloning Efficiency	Relative Total Growth	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
Vehicle Control	Water	0	80	106	97	40	39
			66	95	59	30
			57	92	85	49
			53	107	59	37
Test Chemical	L-Ascorbic acid	125	92	139	64	23	31
			53	85	43	27
			60	78	75	42
		250	42	50	63	50	40
			54	68	69	43
			67	90	56	28
		500	47	58	45	32	40
			33	46	52	53
			58	72	63	36
		750	70	86	68	33	32
			89	99	93	35
			66	74	55	28
		1000	51	77	57	38	35
			62	96	48	26
			72	91	92	43
		1500	54	53	106	66	68*
			53	48	107	68
			79	55	167	70
		2000


Positive Control	Methyl Methane Sulfonate	5	28	18	452	545	532*
			31	23	512	548
			26	19	395	503

Nonactivation Trial: 4 Experiment Call: Negative
		Conc. ug/mL	Cloning Efficiency	Relative Total Growth	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
Vehicle Control	Water	0	110	111	81	25	25
			99#	98	82	28
			108	80	77	24
			106	111	82	26
Test Chemical	L-Ascorbic acid	25	114	149	44	13	18
			102	123	53	17
			97	107	70	24
		50	105	86	79	25	23
			108	90	68	21
			102	100	66	22
		100	83	84	67	27	24
			101	84	79	26
			112	113	69	20
		150	109	71	93	29	27
			101	51	98	32
			74	56	44	20
		200	106	26	94	29	34
			101	25	115	38

		300


Positive Control	Methyl Methane Sulfonate	5	85	58	387	151	183*
			82	51	462	188
			58	39	366	209

Nonactivation Trial: 5 Experiment Call:
		Conc. ug/mL	Cloning Efficiency	Relative Total Growth	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
Vehicle Control	Water	0	109	89	110	34	26
			104	105	72	23
			102	96	85	28
			119	110	68	19
Test Chemical	L-Ascorbic acid	125	97	47	55	19	19
			108	79	62	19
			113	78	66	20
		250	108	65	56	17	21
			97	78	58	20
			105	42	82	26
		500	111	62	74	22	22
			112	85	59	18
			103	67	82	26
		1000	114	63	87	25	27
			111	64	96	29

		1500	149r	17	173	39	28
			89	7	66	25
			84	8	81	32
		1800


Positive Control	Methyl Methane Sulfonate	5					205*
			90	50	454	169
			79	44	572	242

Induced S9 Trial: 1 Experiment Call: Negative
		Conc. ug/mL	Cloning Efficiency	Relative Total Growth	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
Vehicle Control	Water	0	103	105	126	41	44
			97	99	138	48
			82	87	114	46
			89	109	108	40
Test Chemical	L-Ascorbic acid	125	75	95	125	56	49
			71	92	83	39
			63	86	99	53
		250	101	96	104	34	39
			79	93	103	43
			74	115	84	38
		500	89	95	115	43	46
			88	126	119	45
			91	87	133	49
		750	93	93	101	36	38
			82	108	92	38
			99	92	123	42
		1000	79	79	114	48	46
			102	112	104	34
			93	77	157	56
		1500	107	94	157	49	56
			91	88	179	66
			87	82	142	55
Positive Control	3-Methylcholanthrene	2.5	81	40	543	223	196*
			83	61	483	195
			71	58	363	170

Induced S9 Trial: 2 Experiment Call: Equivocal
		Conc. ug/mL	Cloning Efficiency	Relative Total Growth	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
Vehicle Control	Water	0	114	116	76	22	25
			104	93	65	21
			99	99	82	28
			83	92	69	28
Test Chemical	L-Ascorbic acid	600	81	58	122	51	44*
			101	80	102	34
			81	66	116	48
		800	89	75	117	44	43*
			88	61	111	42
			78#	63	103	44
		1000	97	78	105	36	33
			83	65	81	33
			84	71	73	29
		1500	80	63	71	29	38*
			95	67	142	50
			94#	53	99	35
		1800	73	43	96	44	44*
			83	54	113	46
			103	50	129	42
		2000	63	33	87	46	46*
			83	45	102	41
			87	47	132	50
Positive Control	3-Methylcholanthrene	2.5	69	29	458	222	202*
			104#	76	622	200
			100	75	549	183

Induced S9 Trial: 3 Experiment Call:
		Conc. ug/mL	Cloning Efficiency	Relative Total Growth	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
Vehicle Control	Water	0	107	87	108	34	36
			111	127	106	32
			113	62	134	40
			105	124	121	38
Test Chemical	L-Ascorbic acid	250	104#	159	111	36	36
			101	106	101	33
			104	141	121	39
		500	106	177	151	48	50
			109	109	165	50
			113	147	177	52
		1500	115	65	382	111	93*
			101	100	213	70
			102	48	298	98
		1800	99	145	110	37	42
			109	126	144	44
			110	176	147	45
		2000	110	126	137	41	45
			102	116	139	46
			112	116	160	48
Positive Control	3-Methylcholanthrene	2.5	95	27	671	235	235*
			104	31	723	231
			109#	34	778	238

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