Tetrasodium monosilicate hydrate was studied for oral toxicity in female rats in a single dose toxicity test at doses of 300 and 2000 mg/kg, and in a repeat dose and reproductive/developmental toxicity test in both sexes at doses of 0, 2, 10 and 50 mg/kg/day.

With regard to the single dose toxicity, no rats dosed at 300 mg/kg died, but diarrhea and/or soiling of fur were apparent, and autopsy findings revealed thickening of mucosa in the digestive tract. Rats dosed at 2000 mg/kg died with decrease in locomotor activity, vocalization and/or writhing. Autopsy findings revealed edematous appearance in mucosa of forestomach, dark red discoloration in mucosa of glandular stomach, dark red gelatinous contents of duodenum, jejunum and ileum, and dark red discoloration of liver.

Tetrasodium monosilicate hydrate was classified into category 4(>300-2000 mg/kg) of the GHS concerning acute toxicity.

With regard to repeat dose and reproductive/developmental toxicity, rale was observed in the administration period with 50 mg/kg/day. No effects were observed on reproductive performance of parents or on developmental performance of the pups.

The NOAELs for systemic toxicity for parents is considered to be 10 mg/kg/day for males and females, and for reproductive and for developmental toxicity is considered to be 50 mg/kg/day for parents and pups.

Tetrasodium monosilicate hydrate did not induce gene mutations in Salmonella typhimurium TA100, TA1535, TA98, TA1537 and Escherichia coli WP2 uvrA, with or without exogenous metabolic activation under the conditions of this study.

Tetrasodium monosilicate hydrate did not induce structural aberrations or polyploidy under the conditions of this study.

SUMMARIZED DATA FROM THE STUDIES

1. Single Dose Oral Toxicity 1)

Purity	:	90.4 %
Test species/strain	:	Rat/Crj:CD(SD)IGS
Test method	:	OECD Test Guideline 423
Route	:	Oral (gavage)
Dosage	:	300, 2000 mg/kg
Number of animals/group	:	Females, 3
Vehicle	:	Purified water
GLP	:	Yes

　Test results:

In the 300 mg/kg group (6 females), 2 females showed diarrhea and/or soiling of fur from 1 to 4 days after the administration and decrease in body weight on days 1 and 3. They did not show any symptoms 5 days after the administration, and survived through the observation period. At autopsy 14 days after the administration, thickening of the mucosa of the forestomach, glandular stomach and/or limiting ridge and adhesion of stomach to liver, pancreas and/or other surrounding tissues were apparent.

In the 2000 mg/kg group, all 3 females showed decrease in locomotor activity and vocalization and/or writhing within 30 minutes after the administration, and died within 4 hours. Autopsy findings revealed an edematous appearance of the mucosa of the forestomach, dark red discoloration of the mucosa of the glandular stomach, dark red gelatinous contents of the duodenum, jejunum and ileum, and dark red discoloration of the liver.

Tetrasodium monosilicate hydrate was thus classified into category 4(>300-2000 mg/kg) of the GHS regarding acute toxicity.

2. Repeated Dose and Reproduction/Developmental Toxicity 1)

Purity	:	90.4 %
Test species/strain	:	Rat/Crj:CD(SD)IGS
Test method	:	OECD Test Guideline 422
Route	:	Oral (gavage)
Dosage	:	0(vehicle), 2, 10, 50 mg/kg
Number of animals/group	:	Males, 12; females, 12 Recovery group; females, 5
Vehicle	:	Corn oil
Administration period		Males and females satellite group, 42 days Females, from 14 days before mating to day 5 of lactation
Terminal killing		Males and females satellite group, days 43 or 57 Females, day 6 of lactation
GLP	:	Yes

　Test results:

Rale was observed during administration period in 3 males and 3 females of the main group and 1 female of the recovery group given 50 mg/kg/day. No effects were observed on reproductive performance of parents or on developmental performance of the pups.

The NOAELs for systemic toxicity for parents is considered to be 10 mg/kg/day for males and females, and for reproduction and developmental toxicity is considered to be 50 mg/kg/day for parents and pups.

3. Genetic Toxicity

3-1. Bacterial test 1)

Purity	:	90.4 %
Test species/strains	:	Salmonella typhimurium TA100, TA1535, TA98, TA1537, Escherichia coli WP2 uvrA
Test method	:	Guidelines for Screening Mutagenicity Testing of Chemicals (Chemical Substances Control Law of Japan) and OECD Test Guideline 471
Procedures	:	Pre-incubation method
Vehicle	:	Water for injection
Positive controls	:	-S9 mix; 2-(2-Furyl)-3-(5-nitro-2-furyl)acrylamide (TA100, TA98, WP2 uvrA), sodium azide (TA1535) and 9-aminoacridine hydrochloride(TA1537) +S9 mix; 2-Aminoanthracene (all strains)
Dosage	:	[Dose-finding study] -S9 mix; 5, 15, 50, 150, 500, 1500, 5000 μg/plate (all strains) +S9 mix; 5, 15, 50, 150, 500, 1500, 5000 μg/plate (all strains) [Main study] -S9 mix; 62.5, 125, 250, 500, 1000, 2000 μg/plate (all strains) +S9 mix; 62.5, 125, 250, 500, 1000, 2000 μg/plate (all strains)
S9	:	Rat liver; induced with phenobarbital and 5,6-benzoflavone
Plates/test	:	3(1 for the dose-finding test)
Number of replicates		2(1 for the dose-finding test)
GLP	:	Yes

　Test results:

This chemical did not induce gene mutations in Salmonella typhimurium TA100, TA1535, TA98, TA1537 or Escherichia coli WP2 uvrA under the conditions of this study. Growth inhibition was observed at 1000 μg/plate and above in all strains, both with and without 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	[ ]	[ ]	[*]

3-2. Non-bacterial in vitro test(chromosomal aberration test)1)

Purity	:	90.4 %
Type of cell used	:	Chinese hamster lung (CHL/IU) cells
Test method	:	Guidelines for Screening Mutagenicity Testing of Chemicals (Chemical Substances Control Law of Japan) and OECD Test Guideline 473
Vehicle	:	Water for injection
Positive controls	:	-S9 mix; Mitomycin C +S9 mix; Benzo[a]pyrene
Dosage	:	-S9 mix (short-term treatment); 713, 950, 1267 μg/mL +S9 mix (short-term treatment); 1267, 1583, 1900 μg/mL -S9 mix (24 hr continuous treatment); 357, 475, 594, 713, 831, 950, μg/mL
S9	:	Rat liver, induced with phenobarbital and 5,6-benzoflavone
Plates/test	:	4(2: chromosome specimens, 2: measurement of growth rate)
GLP	:	Yes

　Test results:

This chemical did not induce structural aberrations or polyploidy under the conditions of this study.

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

1)	The tests were performed by the Safety Research Institute for Chemical Compounds Co., Ltd., 363-24 Shin-ei, Kiyota-ku, Sapporo-shi, Hokkaido, 004-0839, Japan. Tel +81-11-885-5031, Fax +81-11-885-5313