Genetic Toxicology - Mammalian Cell Mutagenicity

Study Information
Study Attribute	Value
CEBS Accession Number:	002-02690-0009-0000-8
Chemical Name:	Phthalic anhydride
CASRN:	85-44-9
NTP Study Type:	Genetic Toxicology - Mammalian Cell Mutagenicity
NTP Study ID:	358037
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	Dimethyl Sulfoxide	0	68	102	40	20	28
			82	105	61	25
			64	97	64	33
			68	95	72	35
Test Chemical	Phthalic anhydride	12.5	69	89	58	28	26
			64	92	47	24	26
		25	71	89	62	29	32
			77	85	80	34	32
		50	50	65	61	41	44
			57	69	80	47	44
		100	62	40	93	50	39
			58	51	48	28	39
		200	51	14	122	80	71*
			55	12	104	63	71*
Positive Control	Methyl Methane Sulfonate	20	9r	3	107	420
			7r	3	101	470
	Methyl Methane Sulfonate	250	51	61	427	279	286*
			46	42	404	294	286*

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	62	93	78	42	54
			51	89	118	77
			70	115	109	52
			60	103	84	47
Test Chemical	Phthalic anhydride	25	76	115	50	22	41
			73	134	131	60	41
		50	75	93	116	51	58
			75	92	144	64	58
		100	59	73	99	56	60
			64	61	123	64	60
		150	66	30	168	85	78
			51	24	109	72	78
		200	40	6	219	183	218*
			32	5	239	253	218*
		250

Positive Control	Methyl Methane Sulfonate	15	16	14	329	693	684*
Positive Control			18	17	365	676	684*

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