Genetic Toxicology - Mammalian Cell Mutagenicity

Study Information
Study Attribute	Value
CEBS Accession Number:	002-02254-0006-0000-1
Chemical Name:	Hexamethylphosphoramide
CASRN:	680-31-9
NTP Study Type:	Genetic Toxicology - Mammalian Cell Mutagenicity
NTP Study ID:	304965
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 and Non-Toxic
		Conc. uL/mL	Cloning Efficiency	Relative Total Growth	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
Vehicle Control	Water	0	97	86	72	25	25
			86	91	48	19
			107	128	68	21
			81#	94	90	37
Test Chemical	Hexamethylphosphoramide	0.125	117#	110	45	13	18
			81#	101	54	22
			113	93	64	19
		0.25	71	88	38	18	21
			95#	147	71	25
			98	92	58	20
		0.5	79	102	61	26	23
			92	86	68	25
			89	81	46	17
		1	75	75	54	24	24
			104#	104	55	18
			93#	87	87	31
		3	79#	96	75	32	31
			95	88	71	25
			82	100	88	36
		5	81#	72	41	17	22
			83	89	59	24
			96	71	74	26
Positive Control	Ethyl Methane Sulfonate	250	80	38	1019	426	385*
			66	46	724	365
			69#	38	747	363

Nonactivation Trial: 2 Experiment Call: Negative and Non-Toxic
		Conc. uL/mL	Cloning Efficiency	Relative Total Growth	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
Vehicle Control	Water	0	85	105	82	32	37
			74	97	72	32
			84#	91	129	51
			105	107	103	33
Test Chemical	Hexamethylphosphoramide	0.125	102	93	97	32	33
			91#	95	86	32
			81	90	89	37
		0.25	64	75	48	25	28
			75	99	71	32
			73	94	63	29
		0.5	91	96	68	25	28
			81	87	73	30
			76	84	69	30
		1	72	79	74	34	34
			89	104	74	28
			76	77	89	39
		3	94#	103	130	46	42
			90	82	99	37
			76	89	99	43
		5	79	73	89	38	35
			79	86	75	32
			76	77	83	36
Positive Control	Methyl Methane Sulfonate	10	50	21	539	358	390*
			45#	22	529	396
			41	20	512	416

Induced S9 Trial: 1 Experiment Call: Positive
		Conc. uL/mL	Cloning Efficiency	Relative Total Growth	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
Vehicle Control	Water	0	118	130	112	32	32
			76	98	63	28
			99	88	113	38
			88	83	77	29
Test Chemical	Hexamethylphosphoramide	0.25	52	68	47	30	36
			67	97	67	33
			76	79	99	43
		0.5	74	72	65	29	32
			63	73	56	30
			62#	64	71	38
		1.5	56#	78	71	42	40
			66	69	68	34
			100#	76	132	44
		2	80	64	125	52	52*
			81	75	125	52	52*
		3	80	67	139	58	50*
			91	110	108	40
			85	69	134	53
		5	70	55	110	53	57*
			81	69	129	53
			74#	76	147	66
Positive Control	3-Methylcholanthrene	2.5	75	26	645	286	253*
			90	58	574	212
			62	54	480	259

Induced S9 Trial: 2 Experiment Call: Positive
		Conc. uL/mL	Cloning Efficiency	Relative Total Growth	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
Vehicle Control	Water	0	102	165	196	64	84
			58	43	166	96
			78	128	196	84
			66	64	179	90
Test Chemical	Hexamethylphosphoramide	0.25	54	39	447	274	248*
			56	71	444	267
			67	77	411	203
		0.5	62	73	469	254	256*
			58	88	405	235
			53	62	445	281
		1.5	46	11	591	428	396*
			59	24	587	331
			51#	20	657	428
		2	75	34	727	325	425*
			60	28	756	419
			41	26	651	531
		3	45	25	689	514	478*
			41	17	671	541
			54	36	610	380
		5	35	10	741	716	568*
			59	24	831	468
			47	25	734	519
Positive Control	3-Methylcholanthrene	2.5	36	16	664	615	660*
			25	6	517	703
			38	15	761	662

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