Genetic Toxicology - Mammalian Cell Mutagenicity

Study Information
Study Attribute	Value
CEBS Accession Number:	002-01873-0009-0000-0
Chemical Name:	Chlorothalonil
CASRN:	1897-45-6
NTP Study Type:	Genetic Toxicology - Mammalian Cell Mutagenicity
NTP Study ID:	351015
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	Dimethyl Sulfoxide	0	76	97	165	73	77
			52	88	128	82
			74	107	173	78
			66	107	150	75
Test Chemical	Chlorothalonil	0.01	71	95	197	92	80
			64	98	131	68	80
		0.02	52	84	133	85	84
			46	74	113	83	84
		0.04	57	87	106	62	61
			70	91	128	61	61
		0.08	61	71	155	85	83
			62	78	148	80	83
		0.16	58	66	171	99	101
			44#	50	136.5	103	101
		0.32

Positive Control	Methyl Methane Sulfonate	15	18#	15	346.5	648	670*
Positive Control			19	14	388	693	670*

Nonactivation Trial: 2 Experiment Call: Positive
		Conc. ug/mL	Cloning Efficiency	Relative Total Growth	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
Vehicle Control	Dimethyl Sulfoxide	0	68	92	88	43	35
			83	107	69	28
			84	94	73	29
			83	107	104	42
Test Chemical	Chlorothalonil	0.0075	79	89	90	38	37
			92	91	98	36	37
		0.015	96	95	107	37	44
			70	77	105	50	44
		0.03	71	86	80	38	35
			101	88	98	32	35
		0.06	98	82	114	39	35
			91	97	84	31	35
		0.12	68	41	212	103	91*
			77	43	184	79	91*
		0.24

Positive Control	Methyl Methane Sulfonate	15	47	30	181	129	128*
Positive Control			45	32	170	126	128*

Nonactivation Trial: 3 Experiment Call: Positive
		Conc. ug/mL	Cloning Efficiency	Relative Total Growth	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
Vehicle Control	Dimethyl Sulfoxide	0	69	96	137	66	73
			65	91	147	75
			81	94	188	77
			81	118	179	73
Test Chemical	Chlorothalonil	0.025	70	97	158	76	78
			79	92	188	79	78
		0.05	65	88	176	90	93
			74	88	215	97	93
		0.1	68	95	152	75	77
			85	90	202	80	77
		0.15	86	76	223	86	102
			63	53	221	118	102
		0.2	67	30	361	179	187*
			69	37	406	195	187*
		0.25

Positive Control	Methyl Methane Sulfonate	15	53	39	258	161	160*
Positive Control			59	40	281	158	160*

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