Genetic Toxicology - Micronucleus

Study Information
Study Attribute	Value
CEBS Accession Number:	002-02303-0003-0000-3
Chemical Name:	Isobutene
CASRN:	115-11-7
NTP Study Type:	Genetic Toxicology - Micronucleus
NTP Study ID:	A91962
Strain and Species:	B6C3F1 Mouse
Study Result:	Male: Negative; Female: Negative

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Blood

Start Date	Sample Collection Time	Sex	Methodology Used	Route	Dosing Regimen
1992-01-21	24 hour	Male	Slide Scoring	Inhalation	Inhalation x 67, 92 day

		Dose (ppm)	Animal Number	Normochromatic Erythrocytes Trend P: 0.086
		Dose (ppm)	Animal Number	No. Examined	Total MN Cells	Percent NCE	MN Cells per 1000
Vehicle Control	Air	0	XM0001	2000	2	3.4	1.0
		0	XM0002	2000	2	3.5	1.0
		0	XM0003	2000	1	3.1	0.5
		0	XM0004	2000	1	2.6	0.5
		0	XM0005	2000	5	1.4	2.5
Average ± SEM						2.800 ± 0.380	1.100 ± 0.370

Test Chemical	Isobutene	500	AM0201	2000	5	2.6	2.5
		500	AM0202	2000	3	2.4	1.5
		500	AM0203	2000	2	1.4	1.0
		500	AM0204	2000	1	2.7	0.5
		500	AM0205	2000	3	3.8	1.5
Average ± SEM						2.580 ± 0.380	1.400 ± 0.330
Pairwise P							0.274

Test Chemical	Isobutene	1000	BM0401	2000	3	4.0	1.5
		1000	BM0402	2000	4	2.6	2.0
		1000	BM0403	2000	4	2.9	2.0
		1000	BM0404	2000	3	2.5	1.5
		1000	BM0405	2000	3	2.0	1.5
Average ± SEM						2.800 ± 0.330	1.700 ± 0.120
Pairwise P							0.128

Test Chemical	Isobutene	2000	CM0601	2000	3	3.1	1.5
		2000	CM0602	2000	3	2.1	1.5
		2000	CM0603	2000	3	3.0	1.5
		2000	CM0604	2000	5	1.7	2.5
		2000	CM0605	2000	3	1.7	1.5
Average ± SEM						2.320 ± 0.310	1.700 ± 0.200
Pairwise P							0.128

Test Chemical	Isobutene	4000	DM0801	2000	1	1.3	0.5
		4000	DM0802	2000	3	3.6	1.5
		4000	DM0803	2000	3	1.2	1.5
		4000	DM0804	2000	4	2.6	2.0
		4000	DM0805	2000	5	3.4	2.5
Average ± SEM						2.420 ± 0.510	1.600 ± 0.330
Pairwise P							0.168

Test Chemical	Isobutene	8000	EM1001	2000	6	2.9	3.0
		8000	EM1002	2000	4	2.7	2.0
		8000	EM1003	2000	6	2.2	3.0
		8000	EM1004	2000	1	2.8	0.5
		8000	EM1005	2000	3	1.9	1.5
Average ± SEM						2.500 ± 0.190	2.000 ± 0.470
Pairwise P							0.053

Start Date	Sample Collection Time	Sex	Methodology Used	Route	Dosing Regimen
1992-01-22	24 hour	Female	Slide Scoring	Inhalation	Inhalation x 67, 92 day

		Dose (ppm)	Animal Number	Normochromatic Erythrocytes Trend P: 0.541
		Dose (ppm)	Animal Number	No. Examined	Total MN Cells	Percent NCE	MN Cells per 1000
Vehicle Control	Air	0	XF0101	2000	1	2.7	0.5
		0	XF0102	2000	2	3.1	1.0
		0	XF0103	2000	1	2.2	0.5
		0	XF0104	2000	1	2.6	0.5
		0	XF0105	2000	3	2.5	1.5
Average ± SEM						2.620 ± 0.150	0.800 ± 0.200

Test Chemical	Isobutene	500	AF0301	2000	1	3.1	0.5
		500	AF0302	2000	3	2.0	1.5
		500	AF0303	2000	3	3.0	1.5
		500	AF0304	2000	0	2.8	0.0
		500	AF0305	2000	3	2.0	1.5
Average ± SEM						2.580 ± 0.240	1.000 ± 0.320
Pairwise P							0.319

Test Chemical	Isobutene	1000	BF0501	2000	3	2.8	1.5
		1000	BF0502	2000	4	3.5	2.0
		1000	BF0503	2000	1	2.0	0.5
		1000	BF0504	2000	2	1.8	1.0
		1000	BF0505	2000	1	3.5	0.5
Average ± SEM						2.720 ± 0.360	1.100 ± 0.290
Pairwise P							0.246

Test Chemical	Isobutene	2000	CF0701	2000	1	3.8	0.5
		2000	CF0702	2000	2	4.1	1.0
		2000	CF0703	2000	1	3.8	0.5
		2000	CF0704	2000	1	3.2	0.5
		2000	CF0705	2000	1	3.2	0.5
Average ± SEM						3.620 ± 0.180	0.600 ± 0.100
Pairwise P							0.704

Test Chemical	Isobutene	4000	DF0901	2000	2	4.1	1.0
		4000	DF0902	2000	2	2.5	1.0
		4000	DF0903	2000	3	2.3	1.5
		4000	DF0904	2000	1	3.2	0.5
		4000	DF0905	2000	4	2.6	2.0
Average ± SEM						2.940 ± 0.330	1.200 ± 0.250
Pairwise P							0.185

Test Chemical	Isobutene	8000	EF1101	2000	3	3.0	1.5
		8000	EF1102	2000	0	2.8	0.0
		8000	EF1103	2000	1	4.4	0.5
		8000	EF1104	2000	2	3.7	1.0
		8000	EF1105	2000	2	2.5	1.0
Average ± SEM						3.280 ± 0.340	0.800 ± 0.250
Pairwise P							0.500