ABSTRACT

4,4'-Thiobis(6-tert-butyl-m-cresol) was not mutagenic in Salmonella typhimurium TA100, TA98, TA1535, TA1537 and Escherichia coli WP2 uvrA, with or without an exogeneous metabolic activation system.

4,4'-Thiobis(6-tert-butyl-m-cresol) induced neither structural chromosomal aberrations nor polyploidy in CHL/IU cells up to concentrations (0.0009-0.02 mg/ml) causing more than 50% cell growth inhibition, in the absence or presence of an exogenous metabolic activation system.

SUMMARIZED DATA OF THE STUDIES

1. Repeat Dose Toxicity １）

Purity	:	98%
Test species/strain	:	Rat/Crj:CD (SD)
Test method	:	Guidelines for 28-Day Repeat Dose Toxicity Test of Chemicals (Japan)
Route	:	Oral (gavage)
Doses	:	0 (vehicle), 15, 60, 250 mg/kg/day
Number of animals/group	:	Males, 6; females, 6
Vehicle	:	0.5 % gum arabic solution
Administration period	:	Males and females, 28 days
Terminal kill	:	Days 29 or 43
GLP	:	Yes

　Test results:

A temporary decrease in food consumption was noted in both sexes given 250 mg/kg during the early administration period. Laboratory examinations revealed a decrease in pH in females given 60 mg/kg and in both sexes given 250 mg/kg, increases in protein and ketone bodies in females receiving 60 and 250 mg/kg, an increase in platelets in both sexes given 250 mg/kg, and an increase in segmented neutrophils with decreased lymphocytes in females given 250 mg/kg, an increase in inorganic phosphorus in females given 60 and 250 mg/kg, an increase in total cholesterol in both sexes receiving 250 mg/kg, and an increase in phospholipids and blood urea nitrogen and a decrease in glucose in females given 250 mg/kg. An increase in liver weight, macroscopical thickening of the wall of the small intestine and dilatation of the cecum were noted in both sexes given 250 mg/kg. Histopathologically, hypertrophy of centrilobular hepatocytes and villous hyperplasia in the ileum were noted in both sexes given 250 mg/kg. Vacuolation of the epithelial cells in the cecum and colon, and inflammatory cell infiltration in the cecum and/or colon were observed in both sexes given 60 or 250 mg/kg. In the mesenteric lymph nodes, a high incidence of tingible body macrophages was noted in females given 250 mg/kg. Almost all changes disappeared after a 14-day recovery period. The NOEL is considered to be 15 mg/kg/day for both males and females under the conditions of the present study.

2. Genetic Toxicity

2-1. Bacterial test ２）

Purity	:	above 98 %
Test species/strains	:	Salmonella typhimurium TA100, TA1535, TA98, TA1537, Escherichia coli WP2 uvrA
Test methods	:	Guidelines for Screening Mutagenicity Testing of Chemicals (Japan) and OECD (471 and 472)
Procedures	:	Plate incorporation method
Solvent	:	DMSO
Positive controls	:	-S9 mix, 2-(2-Furyl)-3-(5-nitro-2-furyl)acrylamide (TA100, WP2, TA98), Sodium azide (TA1535)and 9-Aminoacridine (TA1537), +S9 mix, 2-Aminoanthracene (five strains)
Doses	:	-S9 mix, 0, 0.781, 1.56, 3.13, 6.25, 12.5, 25 and 50 μg/plate (TA100, TA1535 and TA1537), 0, 3.13 - 200 μg/plate (WP2) and 0, 313 - 5000 μg/plate (WP2) +S9 mix, 0, 12.5, 25, 50, 100, 200, 400 and 800 μg/plate (TA100, TA1535, TA98 and TA1537) and 0, 313 - 5000 μg/plate (WP2)
S9	:	Rat liver, induced with phenobarbital and 5,6-benzoflavone
Plates/test	:	3
Number of replicates	:	2
GLP	:	Yes

　Test results:

This chemical did not induce gene mutations in the S. typhimurium and E. coli strains. Toxicity was observed at 12.5 μg/plate (TA100 and TA1537), 25 μg/plate (TA1535) and 100 μg/plate (TA98) without S9 mix, and 400 μg/plate (TA100, TA1535 and TA1537) and 500 μg/plate (TA98) with S9 mix. No toxicity was observed in WP2 either without S9 mix or with S9 mix.

Genetic effects:
Salmonella typhimurium TA100, TA1535, TA98, TA1537

	+	?	-
Without metabolic activation:	[ ]	[ ]	[*]
With metabolic activation:	[ ]	[ ]	[*]

Escherichia coli WP2 uvrA

	+	?	-
Without metabolic activation:	[ ]	[ ]	[*]
With metabolic activation:	[ ]	[ ]	[*]

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

Purity	:	more than 98%
Type of cell used	:	Chinese hamster lung (CHL/IU) cells
Test method	:	Guidelines for Screening Mutagenicity Testing of Chemicals (Japan)
Solvent	:	Dimethylsulfoxide
Positive controls	:	-S9 mix, Mitomycin C +S9 mix, Cyclophosphamide
Doses	:	-S9 mix (continuous treatment): 0, 0.00050, 0.0010,0.0020 mg/ml -S9 mix (short-term treatment): 0, 0.00023, 0.00045, 0.00090 mg/ml +S9 mix (short-term treatment): 0, 0.0050, 0.010,0.020 mg/ml
S-9	:	Rat liver, induced with phenobarbital and 5,6-benzoflavone
Plates/test	:	2
GLP	:	Yes

　Test results:

Cytogenetic effects were not seen under the conditions of this experiment.

Genotoxic effects:

	clastogenicity			polyploidy
	+	?	-	+	?	-
Without metabolic activation:	[ ]	[ ]	[*]	[ ]	[ ]	[*]
With metabolic activation:	[ ]	[ ]	[*]	[ ]	[ ]	[*]

1)	The tests were performed by Bozo Research Center Inc, 1284, Kamado, Gotemba-shi, Shizuoka, 412, Japan. Tel +81-550-82-2000 Fax +81-550-82-2379
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