3-(dimethoxymethylsilyl)propanethiol

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

01/09/2001 - 09/10/2001

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2001

Report date:

2001

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

no

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

3-trimethoxysilylpropane-1-thiol

EC Number:

224-588-5

EC Name:

3-trimethoxysilylpropane-1-thiol

Cas Number:

4420-74-0

IUPAC Name:

3-(trimethoxysilyl)propane-1-thiol

Test material form:

other: liquid

Method

Target gene:

Salmonella strains: histidine locus; E. coli: tryptophan locus

Species / strain

Species / strain 1

Species / strain / cell type:

E. coli WP2 uvr A

Species / strain 2

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98 and TA 100

Metabolic activation:

with and without

Metabolic activation system:

Aroclor induced rat liver S9

Test concentrations with justification for top dose:

Experiment 1: (TA98, TA 100, TA1537, WP2 uvrA) 100, 333, 1000, 3333, 5000 μg/plate; (TA1535, TA1537) 105, 348, 1045, 3485, 5000 μg/plate (+/-S9)
(TA98, TA100, TA105, TA1535, TA1537, WP2 uvrA) 75, 200, 600, 1800, 5000 μg/plate

Vehicle / solvent:

DMSO

Controls

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Remarks:

2-aminoanthracene, 2-nitrofluorone, sodium azide, 9-aminoacridine, methyl methanesulfonate

Remarks:

historical negative and positive control values included.

Details on test system and experimental conditions:

METHOD OF APPLICATION: preincubation, in agar

DURATION
- Preincubation period: 60 minutes
- Exposure duration: 48-72 hours

Top agar not used with S9 or Sham mix was supplemented with 25 mL of water for each 100 mL of animal top agar. Deionized water was used for the preparation of media and reagents. Bottom agar was 1.5% (w/v), nutrient bottom agar containing 1.5% agar and supplemented with 2.5% (w/v) nutrient broth. 0.5 ml S9 or sham mix, 100 μL of tester strain and 50 μL of vehicle or test article were added to 13x100 mm glass culture tubes pre-heated to 37°C. After vortexing, the mixtures were incubated for an hour in a shaker at 37°C. Following the preincubation, 2 mL of selective top agar was added to each tube and the mixture was vortexed and overlaid onto the surface of 25 mL of minimal bottom agar. When plating the positive controls, the test article aliquot was replaced by 50 μL aliquot of relevant positive control. After the overlay had solidified, the plates were inverted and incubated for approximately 48 to 72 hours at 37°C. Plates that were not counted immediately following the incubation were stored at 2-8°C until colony counting could be conducted.

ACTIVATION:
Bulk S9 was assayed for ability to metabolize 2-aminoanthracene and 7,12-dimethylbenz(a)anthracene to forms mutagenic to S. typhimurium TA 100. S9 mix contained 10% S9, 5mM glucose-6-phosphate, 4 mM NADP, 8mM MgCl2 and 33 mM KCl in 100 mM phosphate buffer pH 7.4. 0.5 ml S9 mix were added to a total volume of 2.65 ml giving a final concentration of approximately 2% S9 in the plates.


SELECTION AGENT (mutation assays): histidine/tryptophan deficient-agar


NUMBER OF REPLICATIONS: All dose levels of test article, vehicle controls and positive controls were plated in triplicate. The experiment was repeated.

DETERMINATION OF CYTOTOXICITY
- Method: condition of bacterial lawn/reduction in number of revertants

Evaluation criteria:

A result is positive if the number of revertants is significantly increased compared with the solvent control to at least 2-fold of the solvent control for TA 98, TA 100 and WP2 uvrA and 3-fold of the solvent control for TA 1535 and TA 1537. There must be a dose related increase in the mean
revertants per plate of at least one tester strain over a minimum of 2 increasing concentrations of test article.

Statistics:

Relevant statistics (standard deviation, mean) were calculated using software by BIOSYS.

Results and discussion

Test results

Test results 1

Species / strain:

E. coli WP2 uvr A

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

5000 μg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Test results 2

Species / strain:

S. typhimurium TA 1535, TA 1537, TA 98 and TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

3485 and 5000 μg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS

- Precipitation: No precipitate was observed.

ADDITIONAL INFORMATION ON CYTOTOXICITY: Cytotoxicity was evident at ≥3333 or 5000 μg/plate.

Remarks on result:

other: No mutagenic potential

Any other information on results incl. tables

Table 1. Experiment 1, preincubation. Number of revertants per plate (mean of 3 plates).

	TA98			TA100			WP2 uvrA
Conc. [μg/ plate]	- MA	+ MA	Cytotoxic (yes/no)	-MA	+ MA	Cytotoxic (yes/no)	- MA	+ MA	Cytotoxic (yes/no)
DMSO	20	21	no	92	116	no	10	12	no
100	19	26	no	99	115	no	13	10	no
333	22	29	no	87	119	no	14	12	no
1000	25	26	no	93	95	no	10	11	no
3333	18	25	no	63	79	no	11	10	no
5000	1	7	yes	4	60	yes	10	10	no
Nitrofluorene 1μg	567	-	-	-	-	-	-	-	-
2-aminoanthacene 1μg	-	608	-	-	488	-	-	162	-
Sodium azide 1μg	-	-	-	408	-	-	-	-	-
Methyl methanesulfonate 1000μg	-	-	-	-	-	-	368	-	-

 

Table 2. Experiment 1, preincubation. Number of revertants per plate (mean of 3 plates).

	TA1537			TA1535
Conc. [μg/ plate]	- MA	+ MA	Cytotoxic (yes/no)	- MA	+ MA	Cytotoxic (yes/no)
DMSO	5	7	no	12	9	no
100	-	7	no	-	13	no
105	6	-	no	10	-	no
333	-	5	no	-	10	no
348	6	-	no	12	-	no
1000	-	6	no	-	10	no
1045	4	-	no	10	-	no
3333	-	4	no	-	7	no
3485	3	-	yes	9	-	yes
5000	0	0	yes	0	1	yes
9-aminoacridine 75μg	580	-	-	-	-	-
2-aminoanthacene 1μg	-	40	-	-	35	-
Methyl methanesulfonate 1000μg	-	-	-	-	-	-
Sodium azide 1μg				231	-	-

 

Table 3: Experiment 2, preincubation. Number of revertants per plate (mean of 3 plates).

	TA98			TA100			TA1535
Conc. [μg/plate]	- MA	+ MA	Cytotoxic (yes/no)	- MA	+ MA	Cytotoxic (yes/no)	- MA	+ MA	Cytotoxic (yes/no)
DMSO	13	13	no	85	97	no	6	8	no
75	13	15	no	86	108	no	9	7	no
200	15	19	no	89	123	no	9	7	no
600	12	16	no	95	85	no	10	7	no
1800	10	16	no	78	100	no	3	9	no
5000	0	0	yes	0	0	yes	0	8	yes
Nitrofluorene 1μg	308
2-aminoanthracene 1μg		258			385			39
Sodium azide 1μg				311			94

  

Table 4. Experiment 2, preincubation. Number of revertants per plate (mean of 3 plates).

	[TA1537]			[WP2 uvrA]
Conc. [μg/plate]	— MA	+ MA	Cytotoxic (yes/no)	— MA	+ MA	Cytotoxic (yes/no)
DMSO	4	8	no	11	10	no
75	3	4	no	10	12	no
200	3	5	no	11	15	no
600	4	4	no	11	10	no
1800	3	4	no	9	11	no
5000	0	1	yes	7	10	yes
9- Aminoacridine  75μg	218
2-aminoanthracene 1μg		45			57
Methyl methanesulfonate 1000μg				266

Applicant's summary and conclusion

Conclusions:

3-trimethoxysilylpropane-1-thiol has been tested for mutagenicity to bacteria, in a study which was conducted according to OECD TG 471, and in compliance with GLP. No evidence of a test-substance related increase in the number of revertants was observed with or without metabolic activation in the initial or the repeat experiments up to limit concentrations in Salmonella typhimurium strains TA98, TA100, TA1535, TA1537 and E coli WP2 uvrA. Cytotoxicity was observed at the highest concentration tested. Appropriate positive and solvent controls were included and gave the expected results. It is concluded that the test substance is negative for mutagenicity to bacteria under the conditions of the test.