Genetic Toxicology - Mammalian Cell Mutagenicity

Study Information
Study Attribute	Value
CEBS Accession Number:	002-01073-0007-0000-0
Chemical Name:	1,3-Dichloro-5,5-dimethylhydantoin
CASRN:	118-52-5
NTP Study Type:	Genetic Toxicology - Mammalian Cell Mutagenicity
NTP Study ID:	659873
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	Ethanol	0	67	88	49	24	24
			79	103	48	20
			70	103	75	36
			65	106	27	14
Test Chemical	1,3-Dichloro-5,5-dimethylhydantoin	6.25	58	85	47	27	25
			71	92	47	22	25
		12.5	68	70	73	36	42*
			57	72	82	48	42*
		25	67	72	86	43	33
			55	64	40	24	33
		50	60	47	90	50	46*
			53	51	67	42	46*
		100	36	9	435	403	391*
			36	9	409	379	391*
Positive Control	Methyl Methane Sulfonate	15	40	30	156	129	108*
			35	21	92	87	108*
	Methyl Methane Sulfonate	250	42	43	363	292	256*
			47	64	314	221	256*

Nonactivation Trial: 2 Experiment Call: Inconclusive
		Conc. ug/mL	Cloning Efficiency	Relative Total Growth	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
Vehicle Control	Ethanol	0	61	99	117	64	58
			66	86	132	67
			63	112	91	48
			59	104	93	53
Test Chemical	1,3-Dichloro-5,5-dimethylhydantoin	20	106	136	148	46	44
			104	131	127	41	44
		40	103	107	106	34	41
			94	84	133	47	41
		60	85	87	81	32
			123r	118	123	33
		80	100	95	116	39	36
			96	62	96	33	36
		100	87	69	109	42	36
			92	93	85	31	36
Positive Control	Methyl Methane Sulfonate	15	29	29	156	176	163*
			28	27	126	149	163*
	Methyl Methane Sulfonate	250	92	151	154	56	58
			90	160	162	60	58

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	77	103	100	43	43
			86	85	136	53
			79	103	88	37
			85	108	93	37
Test Chemical	1,3-Dichloro-5,5-dimethylhydantoin	10	76	93	92	41	41
			86	90	106	41	41
		20	78	66	102	43	46
			92	92	132	48	46
		40	75	61	97	43	48
			83	71	132	53	48
		60	63	67	125	66	61
			70	59	119	57	61
		80	75	48	134	59	61
			85	62	161	63	61
		100

Positive Control	Methyl Methane Sulfonate	20	24	12	223	316	314*
Positive Control			11	6	103	312	314*

Nonactivation Trial: 4 Experiment Call: Positive
		Conc. ug/mL	Cloning Efficiency	Relative Total Growth	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
Vehicle Control	Ethanol	0	86	96	87	34	29
			85	106	56	22
			93	101	74	27
			78	97	77	33
Test Chemical	1,3-Dichloro-5,5-dimethylhydantoin	45	107	53	78	24	28
			89	48	87	32	28
		55	71	36	59	28	34
			81	35	97	40	34
		65	73	28	85	39	37
			69	15	73	36	37
		75	69	21	108	52	51*
			71	21	109	51	51*
		85	43	3	265	207	162*
			78	6	274	117	162*
		95

Positive Control	Methyl Methane Sulfonate	15	43	34	297	233	224*
Positive Control			52	34	337	215	224*

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