Chronic Carcinogenicity Study of Gasoline Vapor Condensate (GVC) and GVC Containing Methyl Tertiary-Butyl Ether in F344 Rats

Figures & data

TABLE 1. Analytical Comparison of Test Materials

Compound	GVC lot API 02-08 (area percent) ^a	GVC lot API 99-01 (area percent) ^b	GMVC lot API 00-02 (area percent)
Isobutane	2.1	3.6	2.2
n-Butane	19.9	15.2	11.1
Isopentane	32.0	35.1	31.0
n-Pentane	5.4	13.2	9.1
Trans-2-pentene	2.4	2.5	2.0
2-Methyl-2-butene	3.3	3.8	2.9
MTBE	–	–	21.3
2,3-Dimethylbutane	6.2	1.6	0.9
2-Methylpentane	9.6	6.3	4.5
3-Methylpentane	6.8	3.6	2.6
n-Hexane	1.2	3.0	2.1
Methylcyclopentane	0.7	1.5	1.1
2,4-Dimethylpentane	0.6	1.0	0.9
Benzene	1.9	2.1	1.5
2-Methylhexane	1.6	1.1	1.0
2,3-Dimethylpentane	1.0	1.1	1.0
3-Methylhexane	2.2	1.3	1.1
Isooctane	0.7	1.3	1.2
Toluene	2.6	3.0	2.5
^aUsed from May 27, 2003–August 15, 2003.
^bUsed from August 13, 2001–May 23, 2003.

TABLE 2. Summary of Test Article Vapor Concentrations

	GVC		GMVC
Target (g/m^3)	Achieved concentrations	Percent of target	Achieved concentrations	Percent of target
0	<1 ^a	NA	NA ^b	NA
2	2.02 ± 0.07	101	2.02 ± 0.07	101
10	10.1 ± 0.34	101	10.0 ± 0.37	100
20	20.3 ± 0.74	101	20.3 ± 0.74	101
Note. Results are the mean ± SD of vapor concentrations obtained in 518 exposure days (combined days for males and females) for GVC and 520 exposure days for GMCV.
^aConcentrations of “zero” were obtained on all but 13 exposure days. On these 13 days, the readings were below the lowest concentration on the standard curve used to calibrate the control chamber Miran 1A (1 g GVC/m^3).
^bValues were below 1 g GMVC/m^3, lowest concentration on the standard curve used to calibrate the control chamber Miran 1A.

FIGURE 1. Survival curves: (a) Survival of GVC male animals. (b) Survival of GVC female animals. (c) Survival of GMVC male animals. (d) Survival of GMVC female animals.

TABLE 3. Mean Survival Days and Day of 25% Mortality for Male and Female Rats

	Male		Female
Group	Mean days of survival (SE)	Estimated day of 25% mortality	Mean Days of survival (SE)	Estimated day of 25% mortality
GVC
Control	660.5 (10.2)	613	686.8 (11.4)	680
Low	666.5 (12.1)	607	642.9 (24.1)	619
Mid	679.9 (11.6)	642	674.8 (12.2)	640
High	669.6 (8.4)	621	678.9 (12.6)	708
GMVC
Control	652.6 (14.4)	626	665.9 (11.5)	632
Low	651.6 (12.8)	633	685.5 (11.9)	680
Mid	675.3 (9.4)	633	680.9 (15.5)	660
High	674.1 (9.5)	645	697.3 (10.6)	715

FIGURE 2. Growth curves: (a) Growth curves for male and female rats exposed to air or GVC. (b) Growth curves for male and female rats exposed to air or GMVC.

TABLE 4. Terminal Body Weight and Selected Organ Weights

	Terminal body weight, mean ± SD (g) (n)		Kidney weight, mean ± SD (g) (n)		Testes/ovaries weight, mean ± SD (g)		Lung weight, mean ± SD (g)
Target (g/m^3)	Male	Female	Male	Female	Male	Female	Male	Female
GVC
0	377.5 ± 31.3 (18)	273.9 ± 20.5 (29)	3.284 ± 2.189 (18)	1.747 ± 0.104 (29)	4.889 ± 2.113 (18)	0.713 ± 3.246 (29)	2.191 ± 0.751 (18)	1.343 ± 0.125 (29)
2	388.3 ± 24.0 (22)	261.5 ± 24.1 (27)	2.761 ± 0.199 (22)	1.948 ± 0.780 (27)	6.133 ± 2.135 (21)	0.104 ± 0.018 (27)	1.958 ± 0.262 (22)	1.366 ± 0.203 (27)
10	357.8 ± 36.3 (26)	247.8 ± 22.4 ^b (27)	2.834 ± 0.534 (26)	1.853 ± 0.238 ^a (27)	5.649 ± 2.678 (25)	0.148 ± 0.158 (27)	2.115 ± 0.446 (26)	1.562 ± 0.740 (27)
20	341.9 ± 60.7 ^a (17)	251.0 ± 19.4 ^b (33)	2.857 ± 0.256 (17)	1.840 ± 0.122 ^a (33)	4.963 ± 2.626 (17)	0.323 ± 0.889 (33)	2.389 ± 0.674 (17)	1.351 ± 0.130 (32)
GMVC
0	390.0 ± 18.2 (14)	265.4 ± 33.3 (22)	2.906 ± 0.230 (14)	1.951 ± 0.348 (22)	5.183 ± 3.133 (14)	0.117 ± 0.099 (22)	1.917± 0.281 (14)	1.562 ± 0.503 (22)
2	375.5 ± 35.2 (16)	273.5 ± 20.4 (30)	3.053 ± 0.598 (16)	1.900 ± 0.171 (30)	5.378 ± 1.948 (16)	0.126 ± 0.062 (30)	2.237 ± 0.566 (16)	1.366 ± 0.145 (30)
10	368.7 ± 28.5 (20)	256.3 ± 21.9 (30)	2.960 ± 0.236 (20)	1.908 ± 0.171 (30)	5.996 ± 2.419 (20)	0.141 ± 0.174 (30)	2.103 ± 0.411 (20)	1.360 ± 0.305 (30)
20	357.0 ± 28.4 ^b (19)	243.6 ± 15.7 ^a (33)	3.054 ± 0.365 (19)	1.933 ± 0.155 (33)	6.324 ± 2.448 (19)	0.105 ± 0.022 (33)	2.128 ± 0.570 (19)	1.374 ± 0.278 (33)
^aMean significantly different from control; data nonhomogeneous by Bartlett's test. Means compared using a modified t-test.
^bMean significantly different from control; data homogeneous by Bartlett's test. Means compared using Dunnett's test of significance.

TABLE 5a. GVC: Summary of Select Proliferative Lesions in Male and Female Rats

Tissue	Diagnosis	Control (0 g/m^3)	Low (2 g/m^3)	Mid (10 g/m^3)	High (20 g/m^3)
Males
Kidney	Number examined	50	50	50	50
	Adenoma, renal tubule	1 (2%)	1 (2%)	4 (8%)	0 (0%)
	Carcinoma, renal tubule	0 (0%)	0 (0%)	3 (6%)	0 (0%)
	Renal tubule adenoma and carcinoma, combined	1 (2%)	1 (2%)	7 (14%)	0 (0%)
Nasal passages (Note that the same tumor may occur at more than one level.)	Turbinate level 2
	Number examined	50	50	50	50
	Carcinoma, squamous cell	0 (0%)	0 (0%)	0 (0%)	1 (2%)
	Turbinate level 3
	Number examined ^a	50	50	49	50
	Carcinoma, squamous cell ^b	0 (0%)	0 (0%)	0 (0%)	3 (6%)
	Turbinate level 4
	Number examined	50	50	49	50
	Carcinoma, squamous cell	0 (0%)	1 (2%)	0 (0%)	3 (6%)
Testes	Number examined	50	49	50	50
	Mesothelioma, malignant ^c	0 (0%)	0 (0%)	4 (8%)	0 (0%)
	Adenoma, interstitial cell	48 (96%)	46 (94%)	50 (100%)	49 (98%)
Thyroid	Number examined	50	29	27	50
	Hyperplasia, follicular cell ^d, ^e	1 (2%)	0 (0%)	2 (7%)	6 (12%)
	Average severity	0.0 ± 0.1	0.0 ± 0.0	0.1 ± 0.4	0.2 ± 0.5
	Adenoma, follicular cell	0 (0%)	2 (7%)	0 (0%)	2 (4%)
	Carcinoma, follicular cell^c	0 (0%)	0 (0%)	2 (7%)	0 (0%)
	Follicular cell adenoma and carcinoma, combined	0 (0%)	2 (7%)	2 (7%)	2 (4%)
Spleen	Number examined	50	34	38	50
	Leukemia, mononuclear cell	32 (64%)	23 (68%)	25 (66%)	32 (64%)
Tissue	Diagnosis	Control (0 g/m^3)	Low (2 g/m^3)	Mid (10 g/m^3)	High (20 g/m^3)
Females
Spleen	Number examined	50	25	32	50
	Leukemia, mononuclear cell ^c	13 (26%)	14 (56%)	18 (56%)	15 (30%)
^aMid-dose turbinate levels 3 and 4 for one animal were autolytic, resulting in an n of 49.
^bSignificant trend for increased incidence with increasing exposure concentration, Cochran–Armitage test.
^cSignificant trend for increased incidence with increasing exposure concentration, Fisher's exact test.
^dAverage ± SD of the severity score for all animals examined (both affected and unaffected). Unaffected animals were assigned a severity score of zero.
^eSignificant increasing trend with exposure concentration with the Cochran–Armitage and logistic tests.

TABLE 5b. GMVC: Incidences of Proliferative (Neoplastic and Hyperplastic) Lesions in Rats

		Control (0 g/m^3)	Low (2g/m^3)	Mid (10 g/m^3)	High (20 g/m^3)
Males
Kidney	Number examined	50	50	50	50
	Adenoma, renal tubule	0 (0%)	0 (0%)	6 (12%) ^a	2 (4%)
	Carcinoma, renal tubule	0(0%)	1(2%)	0(0%)	1(2%)
	Renal tubule adenoma and carcinoma, combined ^b	0(0%)	1(2%)	6(12%) ^c	3(6%)
Nasal sections (Note that the same tumor may appear in more than one level.)	Turbinate level 1
	Number examined	50	50	50	50
	Hyperplasia	3(6%)	0(0%)	3(6%)	4(8%)
	Average severity	0.2	0.0	0.1	0.2
	Turbinate level 2
	Number examined	50	50	50	50
	Hyperplasia	0(0%)	2(4%)	2(4%)	3(6%)
	Average severity	0.0	0.1	0.1	0.2
	Carcinoma, squamous cell	1(2%)	0(0%)	0(0%)	0(0%)
	Turbinate level 3
	Number examined	50	50	50	50
	Carcinoma, squamous cell	0(0%)	1(2%)	0(0%)	1(2%)
	Turbinate level 4
	Number examined	50	50	50	50
	Carcinoma, squamous cell	0(0%)	2(4%)	0(0%)	2(4%)
Thyroid	Number examined	50	35	31	50
	Hyperplasia, follicular cell	0(0%)	0(0%)	1(3%)	0(0%)
	Average severity	0.0 ± 0.0	0.0 ± 0.0	0.1 ± 0.5	0.0 ± 0.0
	Adenoma, follicular cell	2(4%)	0(0%)	0(0%)	3(6%)
	Carcinoma, follicular cell	1(2%)	0(0%)	1(3%)	3(6%)
	Follicular cell adenoma and carcinoma, combined	3(6%)	0(0%)	1(3%)	5(10%)
Testes	Number. examined	50	50	50	50
	Adenoma, interstitial cell ^d	43(86%)	47(94%)	48(96%)	50(100%) ^e
	Mesothelioma	0 (0%)	1(2%)	1(2%)	2(4%)
Spleen	Number examined	50	39	38	50
	Leukemia, mononuclear^f	27(54%)	31(79%)^e	31(82%)^e	31(62%)
Females
Spleen	Number examined	50	22	24	50
	Leukemia, mononuclear	27(54%)	12(55%)	11(46%)	23(46%)
Mammary Gland	Number examined	49	20	22	47
	Fibroadenoma ^f	0(0%)	3(15%)^e	2(9%)	5(11%) ^e
^aIncidence is significantly different from controls and from the 2-g/m^3 group, Fisher's exact test.
^bA positive trend toward increased incidence with increasing exposure concentration found with the Cochran–Armitage test.
^c Incidence is significantly different from controls, Fisher's exact test.
^dA positive trend with increasing exposure concentration found with the Fisher's exact, Cochran–Armitage and Logistic tests.
^eIncidence significantly different from controls, Fisher's exact test.
^fA positive trend with increasing exposure concentration found with the Fisher's exact test.

TABLE 6. Comparison of Chronic Progressive Nephropathy in Rats Inhaling GMVC and GVC for 2 Years

	0 g/m^3	2 g/m^3	10 g/m^3	20 g/m^3
GVC
Males
Incidence ^a	49/50 (98%)	49/50 (98%)	50/50 (100%)	50/50 (100%)
Average severity ^b	2.4 ± 0.85	2.5 ± 0.81	2.9 ± 0.79 ^c	2.9 ± 0.77 ^c
Females
Incidence	27/50 (54%)	12/24 (50%)	16/25 (64%)	32/50 (64%)
Average severity	0.66 ± 0.69	1.0 ± 1.2	0.92 ± 0.86	0.86 ± 0.78
GMVC
Males
Incidence	44/50 (88%)	47/50 (94%)	50/50 (100%)	46/50 (92%)
Average severity	1.9 ± 0.99	2.1 ± 0.92	2.6 ± 0.64 ^c	2.7 ± 0.94 ^c
Females
Incidence	42/50 (84%)	17/20 (85%)	15/21 (71%)	43/50 (86%)
Average severity	1.0 ± 0.64	1.0 ± 0.56	1.0 ± 0.80	1.5 ± 0.91 ^c
^aIncidence (percent).
^bAverage ± SD of severity score of the number of animals examined (both affected and unaffected). Unaffected animals were assigned a severity score of zero.
^cSignificantly different from controls (p < .05).

TABLE 7. Incidence and Severity of Respiratory Epithelial Degeneration

	GVC				GMVC
	0 g/m^3	2 g/m^3	10 g/m^3	20 g/m^3	0 g/m^3	2 g/m^3	10 g/m^3	20 g/m^3
Males
Turbinate level 2
Number examined	50	50	50	50	50	50	50	50
Number with lesions (%)	2 (4)	3 (6)	7 (14)	11 (22) ^a	0	1 (2)	2 (4)	3 (6)
Average severity ^b	0.0 ± 0.2	0.1 ± 0.2	0.2 ± 0.6	0.2 ± 0.5	–	0.0 ± 0.1	0.1 ± 0.4	0.1 ± 0.6
Turbinate level 3
Number examined	50	50	49	50	50	50	50	50
Number with lesions (%)	1 (2)	0 (0)	7 (14) ^c	2 (4)	0 (0)	0 (0)	0 (0)	0 (0)
Average severity	0.0 ± 0.3	–	0.2 ± 0.5	0.0 ± 0.2	–	–	–	–
Females
Turbinate level 2
Number examined	49	49	50	50	50	50	50	50
Number with lesions (%)	8 (16)	11 (22)	18 (36)	26 (52) ^a, ^d, ^e	0 (0)	1 (2)	7 (14)	6 (12) ^a, ^f
Average severity	0.2 ± 0.5	0.3 ± 0.6	0.5 ± 0.8	0.8 ± 0.8 ^c	–	0.0 ± 0.1	0.3 ± 0.7	0.2 ± 0.6
Turbinate level 3
Number examined	49	49	50	50	50	50	50	50
Number with lesions (%)	2 (4)	0 (0)	8 (16) ^g	12 (24) ^a, ^e	0 (0)	0 (0)	0 (0)	0 (0)
Average severity	0.0 ± 0.2	–	0.2 ± 0.5	0.4 ± 0.7	–	–	–	–
^aSignificant trend for increased incidence with increasing exposure level, Cochran–Armitage and logistic tests.
^bAverage ± SD of severity score of the number of animals examined (both affected and unaffected). Unaffected animals were assigned a severity score of zero.
^cSignificantly different from the low-level group, Fisher's exact test.
^dOverall severity/incidence is significantly greater than control, Kolmorogov–Smirnoff test.
^eSignificantly different from the control and low-level groups, Fisher's exact test.
^fSignificant trend for increased incidence with increasing exposure level, Fisher's exact test.
^gSignificantly different from the low-level group, Fisher's exact test.

TABLE 8. Incidence and Severity of Olfactory Epithelial Degeneration

	GVC				GMVC
	0 g/m^3	2 g/m^3	10 g/m^3	20 g/m^3	0 g/m^3	2 g/m^3	10 g/m^3	20 g/m^3
Males
Turbinate level 2
Number examined	50	50	50	50	50	50	50	50
Number with lesions (%)	0 (0)	0 (0)	2 (4)	2 (4)	0 (0)	5 (10)	7 (14)	6 (12) ^a
Average severity ^b	–	–	0.0 ± 0.2	0.0 ± 0.2	–	0.2 ± 0.5	0.2 ± 0.6	0.2 ± 0.7
Turbinate level 3
Number examined	50	50	49	50	50	50	50	50
Number with lesions (%)	15 (30)	3 (6)	7 (14) ^c	4 (8) ^a	2 (4)	1 (2)	7 (14)	7 (14) ^d
Average severity	0.3 ± 0.5	0.1 ± 0.4	0.2 ± 0.4	0.1 ± 0.3	0.0 ± 0.2	0.0 ± 0.3	0.2 ± 0.6	0.3 ± 0.8
Turbinate level 4
Number examined	50	50	49	50	50	50	50	50
Number with Lesions (%)	18 (36)	10 (20)	6 (12)	1 (2) ^e, ^f, ^g	0	0	1 (2)	1 (2)
Average Severity	0.4 ± 0.5	0.2 ± 0.4	0.2 ± 0.6	0.0 ± 0.1	–	–	0.0 ± 0.1	0.0 ± 0.1
Females
Turbinate level 2
Number examined	49	49	50	50	50	50	50	50
Number with Lesions (%)	0 (0)	0 (0)	7 (14)	2 (4)	4 (8)	5 (10)	6 (12)	10 (20)
Average severity	–	–	0.3 ± 0.7	0.0 ± 0.2	0.1 ± 0.4	0.2 ± 0.5	0.2 ± 0.6	0.3 ± 0.6
Turbinate level 3
Number examined	49	49	50	50	50	50	50	50
Number with lesions (%)	15 (31)	13 (27)	11 (22)	13 (26)	4 (8)	2 (4)	10 (20)	8 (16)
Average severity	0.3 ± 0.5	0.3 ± 0.5	0.3 ± 0.5	0.3 ± 0.5	0.1 ± 0.5	0.1 ± 0.3	0.4 ± 0.9	0.3 ± 0.8
Turbinate level 4
Number examined	49	49	50	49	50	50	50	50
Number with lesions (%)	21 (43)	10 (20)	7 (14) ^g	2 (4) ^e, ^f, ^g	3 (6)	0 (0)	0 (0)	3 (6)
Average severity	0.4 ± 0.5	0.2 ± 0.4	0.2 ± 0.4	0.0 ± 0.2	0.0 ± 0.3	–	–	0.1 ± 0.2
^aSignificant trend for increasing incidence with exposure concentration, Cochran–Armitage, logistic, and Fisher's exact tests.
^bAverage ± SD of severity score of the number of animals examined (both affected and unaffected). Unaffected animals were assigned a severity score of zero.
^cSignificantly greater than the low-level group, Fisher's exact test.
^dSignificant trend for increased incidence with increasing exposure level, Cochran–Armitage and logistic tests.
^eSignificant trend for decreased incidence with increasing exposure level, Cochran–Armitage, logistic, and Fisher's exact tests.
^fOverall severity/incidence is significantly less than control, Kolmorogov–Smirnoff test.
^gSignificantly less than control, Fisher's exact test.