ABSTRACT

The single dose oral toxicity test revealed an LD50 of more than 2000 mg/kg.

In the repeat oral toxicity test, urinary examination revealed an increase in urine volume and a fall in specific gravity in both sexes of the 750 mg/kg group. Absolute or relative liver weights increased in males and females of the 750 mg/kg group and males of the 150 mg/kg group, absolute or relative kidney weights increased in males of the 150 and 750 mg/kg groups, and absolute and relative spleen weights decreased in females of the 750 mg/kg group. Macroscopically, enlargement of the liver was evident in males and females of the 750 mg/kg group, and enlargement and paleness of the kidneys were found in females of the 150 and 750 mg/kg groups. Histopathological examination revealed swelling of liver cells in both sexes of the 150 and 750 mg/kg groups and eosinophilic bodies in the renal tubules in males of the 150 and 750 mg/kg groups. These changes tended to recover with a 14 day recovery period. The NOEL for repeat dose toxicity is considered to be 30 mg/kg/day for both sexes.

Triisobutylene was not mutagenic in Salmonella typhimurium TA100, TA98, TA1535, TA1537 and Escherichia coli WP2 uvrA. Neither structural nor numerical chromosomal aberrations were induced in CHL/IU cells up to the concentration going 50% cell growth inhibition or the limit concentration of 10 mM, in the absence or presence of an exogenous metabolic activation system.

SUMMARIZED DATA FROM THE STUDIES

1.Single Dose Oral Toxicity 1)

Purity	:	99.13%
Test species/strain	:	Rat/Crj:CD (SD)
Test method	:	OECD Test Guideline 401
Dosage	:	2000 mg/kg
Number of animals	:	Male, 5; female, 5/group
Vehicle	:	Corn oil
GLP	:	Yes

　Test results:

During the course of the study, a decrease in spontaneous motor activity and diarrhea were observed in both males and females as well as an loose stool in one male rat, as clinical signs. However, no deaths occurred in either males or females. The test substance did not cause any changes in body weight. No macroscopic abnormalities were seen by pathological examination that could be attributed to treatment with the test substance.

LD50: Male > 2000 mg/kg, female > 2000 mg/kg.

2. Repeat Dose Toxicity 1)

Purity	:	99.13%
Test species/strain	:	Rat/Crj:CD (SD)
Test method	:	Guidelines for 28-day Repeat Dose Toxicity Testing of Chemicals (Japan)
Route	:	Oral
Dose	:	0 (vehicle), 30, 150, 750 mg/kg/day
Number of animals	:	Male, 5; female, 5 /group
Vehicle	:	Corn oil
Administration period	:	Male and female, 28 days
Terminal kill	:	Male and female, days 29 or 43
GLP	:	Yes

　Test results:

The test substance did not induce any toxic effects in terms of clinical signs, body weight or food consumption. On hematological and blood chemical analyses, red blood cell counts decreased slightly in females of the 150 and 750 mg/kg groups, and the prothrombin time was shortened slightly in females of the 750 mg/kg group. An increase in albumin was observed in males and females of the 750 mg/kg groups, an increase in creatinine was observed in males of the 750 mg/kg group and a decrease in GOT was observed in females of the 750 mg/kg group. Urine volume increased in males and females of the 750 mg/kg group and the specific gravity of the urine fell in males and females of the 750 mg/kg group. Absolute or relative liver weights increased in males of the 150 mg/kg group, and males and females of the 750 mg/kg groups. Additionally, absolute or relative kidney weights increased in males of the 150 and 750 mg/kg groups, and absolute and relative spleen weights decreased in females of the 750 mg/kg group. Macroscopically, enlargement of the liver was observed in males and females of the 750 mg/kg group, and enlargement and paleness of the kidneys were found in females of the 150 and 750 mg/kg groups. Histopathological examination revealed swelling of liver cells in both sexes of the 150 and 750 mg/kg groups, and eosinophilic bodies in renal tubules in males of the 150 and 750 mg/kg groups.

The NOEL is considered to be 30 mg/kg/day for both males and females under the conditions of the present study.

3. Genetic Toxicity

3-1 Bacterial test 2)

Purity	:	99.13%
Test species/strains	:	S.typhimurium TA100, TA1535, TA98, TA1537 E. coli WP2 uvrA
Test method	:	Guidelines for Screening Mutagenicity Testing of Chemicals (Japan)
Procedures	:	Plate incorporation method
Solvent	:	Acetone
Positive controls	:	-S9, AF-2 (TA100, WP2, TA98), sodium azide (TA1535) and 9-aminoacridine (TA1537) +S9, 2-aminoanthracene (all strains)
Dosage	:	0, 312.5, 625, 1250, 2500, 5000μg/plate
S-9	:	Rat liver, induced with phenobarbital and 5,6-benzoflavone
Plates/test	:	3
Number of replicates	:	2
GLP	:	Yes

　Test results:

Minimum concentration of test substance at which toxicity was observed:

No toxicity was observed up to a concentration of 5000 μg/plate with or without metabolic activation.

Genetic effects:
S. typhimurium TA100, TA1535, TA 98, TA1537

	+	?	-
with metabolic activation	[ ]	[ ]	[*]
without metabolic activation	[ ]	[ ]	[*]

E. coli WP2 uvrA

with metabolic activation	[ ]	[ ]	[*]
without metabolic activation	[ ]	[ ]	[*]

3-2. Non-bacterial in vitro test (chromosomal aberration test) 2)

Purity	:	99.13%
Type of cell used	:	Chinese hamster CHL/IU cells
Test method	:	Guidelines for Screening Mutagenicity Testing of Chemicals (Japan)
Solvent	:	Acetone
Positive controls	:	-S9, Mitomycin C +S9, Cyclophosphamide
Dosage	:	-S9 (continuous treatment): 0, 0.005, 0.011, 0.021 mg/ml -S9 (short-term treatment): 0, 0.0011, 0.0021, 0.0042 mg/ml +S9 (short-term treatment): 0, 0.43, 0.85, 1.70 mg/ml
S-9	:	Rat liver, induced with phenobarbital and 5,6-benzoflavone
Plates/test	:	2
GLP	:	Yes

　Test results:

Lowest concentration producing cytogenetic effects in vitro:

without metabolic activation (continuous treatment ): > 0.021 mg/ml

without metabolic activation (short-term treatment): > 0.0042 mg/ml

with metabolic activation (short-term treatment): > 1.70 mg/ml

Genotoxic effects:

	clastogenicity			polyploidy
	+	?	-	+	?	-
without metabolic activation:	[ ]	[ ]	[*]	[ ]	[ ]	[*]
with metabolic activation:	[ ]	[ ]	[*]	[ ]	[ ]	[*]

1)	The tests were performed by the Biosafety Research Center, Foods, Drugs and Pesticides (An-pyo Center), 582-2 Shioshinden Arahama, Fukude-cyo,Iwata-gun, Shizuoka 437-12, Japan. Tel +81-538-58-1266 Fax +81-538-58-1393
2)	The tests were performed by the Hatano Research Institute, Food and Drug Safety Center, 729-5 Ochiai, Hadano-shi, Kanagawa 257, Japan. Tel +81-463-82-4751 Fax +81-463-82-9627