Carbamic acid, N-[(dimethoxymethylsilyl)methyl]-, methyl ester

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:

20 Nov 2003 - 07 Jan 2004

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2004

Report date:

2004

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Version / remarks:

adopted 1997

Deviations:

yes

Remarks:

2-aminoanthracene was used as the sole indicator of the efficacy of the S9-mix

GLP compliance:

yes (incl. QA statement)

Remarks:

Bayerisches Landesamt für Arbeitsschutz, Arbeitsmedizin und Sicherheitstechnik, München, Germany

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

methyl N-{[dimethoxy(methyl)silyl]methyl}carbamate

Cas Number:

23432-65-7

Molecular formula:

C6H15NO4Si

IUPAC Name:

methyl N-{[dimethoxy(methyl)silyl]methyl}carbamate

Test material form:

liquid

Method

Target gene:

His operon

Species / strain

Species / strain 1

Species / strain / cell type:

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

Species / strain 2

Species / strain / cell type:

S. typhimurium TA 102

Metabolic activation:

with and without

Metabolic activation system:

cofactor supplemented post-mitochondrial fraction (S9 mix), prepared from the livers of rats treated with Phenobarbital/beta-Naphtoflavone.

Test concentrations with justification for top dose:

31.6, 100, 316, 1000, 2500, 5000 µg/plate

Vehicle / solvent:

- Vehicle/solvent used: DMSO
- Justification for choice of solvent/vehicle: The solvent was compatible with the survival of the bacteria and the S9 activity.

Controls

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

sodium azide

methylmethanesulfonate

other: 4-nitro-o-phenylene-diamine (4-NOPD), 2-aminoanthracene (2-AA)

Remarks:

Without S9: sodium azide (10 µg/plate for TA 100 and TA 1535); 4-NOPD (10 and 40 µg/plate for TA 98 and TA 1537); MMS (1 µL/plate for TA 102); With S9: 2-AA (2.5 µg/plate for TA 98, TA 100, TA 1535, TA 1537; 10 µg/plate for TA 102)

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar (plate incorporation); preincubation

DURATION
- Preincubation period: 60 minutes
- Exposure duration: 48 h

NUMBER OF REPLICATIONS: 3 plates per concentration in two independent experiments (plate incorporation and preincubation)

DETERMINATION OF CYTOTOXICITY
- Method: reduced background lawn, reduction in the number of revertants, degree of survival of treated cultures

METABOLIC ACTIVATION
The S9 fraction was stored in liquid nitrogen. The S9 mix was freshly prepared on the day of the test according to AMES (1933): containing 15% S9 and the following components (final concentrations):
- 8 mM MgCl2
- 33 mM KCI-salt solution
- 5 mM glucose-6-phosphate
- 5 mM NADP
in 100 mM phosphate buffer, pH 7.4

Evaluation criteria:

A test item is considered as mutagenic if:
- a dose-related increase in the number of revertants occurs and/or
- a reproducible biologically relevant positive response for at least one of the dose groups occurs in at least one strain with or without metabolic activation
A biologically relevant increase is described as follows:
- if in strains TA 100 and TA 102 the number of reversions is at least twice as high
- if in strains TA 1535, TA 1537 and TA 98 the number of reversions is at least three times higher
as compared to the spontaneous reversion rate.

Statistics:

Mean values and standard deviation were calculated

Results and discussion

Test results

Test results 1

Key result

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity nor precipitates, but tested up to recommended limit concentrations

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Test results 2

Key result

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity nor precipitates, but tested up to recommended limit concentrations

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Test results 3

Key result

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity nor precipitates, but tested up to recommended limit concentrations

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Test results 4

Key result

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity nor precipitates, but tested up to recommended limit concentrations

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Test results 5

Key result

Species / strain:

S. typhimurium TA 102

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity nor precipitates, but tested up to recommended limit concentrations

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS
- Precipitation: no precipitation was reported

RANGE-FINDING/SCREENING STUDIES:
In a preliminary toxicity test TA 98 and TA 100 were treated with the test item up to 5000 µg/plate. No toxicity was observed up to 5000 µg/plate.

COMPARISON WITH HISTORICAL CONTROL DATA: no data given

Any other information on results incl. tables

Table 1: Test results of main test 1 (Plate incorporation test).

With or without S9-Mix	Test substance concentration	Mean number of revertant colonies per plate in the plate incorporation test
	(μg/plate)	(average of 3 plates±standard deviation)
		Base-pair substitution type			Frameshift type
		TA 100	TA 102	TA 1535	TA1537	TA98
–	A. dest.	124±8	327±6	27±4	12±7	31±3
–	Solvent control	99±11	273±16	28±7	11±6	33±2
–	31.6	106±19	286±16	24±5	14±6	36±2
–	100	109±4	279±11	22±6	15±5	27±8
–	316	104±9	301±7	23±5	15±2	33±6
–	1000	115±4	294±8	21±4	17±3	27±2
–	2500	103±14	319±26	19±4	12±3	28±8
–	5000	116±5	308±19	24±9	12±6	30±8
Positive controls, –S9	Name	sodium azide	MMS	sodium azide	4-NOPD	4-NOPD
	Concentrations (μg/plate)	10	1 µL/plate	10	40	10
	Average of 3 plates±sd	402±28	1724±129	1032±46	179±11	774±59
+	A. dest.	124±22	355±56	12±2	15±4	46±9
+	Solvent control	116±13	289±31	11±3	13±1	36±7
+	31.6	116±7	330±28	15±7	17±2	38±2
+	100	108±16	369±40	21±1	14±1	41±4
+	316	116±14	330±23	16±7	13±9	38±12
+	1000	113±17	360±19	16±4	19±3	35±1
+	2500	128±4	352±5	11±3	13±4	34±4
+	5000	130±9	375±23	15±6	13±3	38±6
Positive controls,+S9	Name	2-aminoanthracene	2-aminoanthracene	2-aminoanthracene	2-aminoanthracene	2-aminoanthracene
	Concentrations (μg/plate)	2.5	10	2.5	2.5	2.5
	Average of 3 plates±sd	1991±36	804±20	226±29	282±9	1207±142

 

Table 2: Test results of main test 2 (Pre-incubation test).

With or without S9-Mix	Test substance concentration	Mean number of revertant colonies per plate in the pre-incubation test
	(μg/plate)	(average of 3 plates±standard deviation)
		Base-pair substitution type			Frameshift type
		TA 100	TA 102	TA 1535	TA1537	TA98
–	A. dest.	113±11	192±19	21±4	17±6	35±5
–	Solvent control	99±5	141±8	17±4	11±	27±4
–	31.6	128±3	166±12	16±4	17±7	25±4
–	100	115±18	159±11	20±1	17±4	26±3
–	316	117±21	151±1	24±2	15±4	25±3
–	1000	114±1	154±20	17±4	17±1	25±3
–	2500	123±5	131±9	24±1	17±2	24±5
–	5000	123±10	166±6	23±3	17±1	31±4
Positive controls, –S9	Name	sodium azide	MMS	sodium azide	4-NOPD	4-NOPD
	Concentrations (μg/plate)	10	1 µL/plate	10	40	10
	Average of 3 plates±sd	540±49	2246±80	1168±84	152±15	848±29
+	A. dest.	143±12	304±32	16±6	24±8	45±5
+	Solvent control	128±9	211±39	11±2	11±0	39±11
+	31.6	132±10	258±15	18±2	13±3	38±10
+	100	127±12	246±1	13±6	18±8	43±12
+	316	120±8	223±17	15±3	14±2	33±4
+	1000	128±3	221±25	19±4	11±4	42±2
+	2500	122±25	209±12	12±6	15±4	38±8
+	5000	122±22	233±31	21±3	16±2	35±9
Positive controls,+S9	Name	2-aminoanthracene	2-aminoanthracene	2-aminoanthracene	2-aminoanthracene	2-aminoanthracene
	Concentrations (μg/plate)	2.5	10	2.5	2.5	2.5
	Average of 3 plates±sd	2373±144	839±197	178±31	204±44	2033±238

MMS - Methylmethanesulfonate

4 -NOPD - 4 -nitro-o-phenylene-diamine

Applicant's summary and conclusion

Conclusions:

Interpretation of results::
negative