Dichloro(methyl)silane

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Remarks:

Type of genotoxicity: gene mutation

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: The study was conducted under GLP according to an appropriate OECD test guideline, with acceptable restrictions. The restrictions were that only four strains or bacteria tested.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1988

Report date:

1988

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Principles of method if other than guideline:

Ames et al. (1973, 1975); Maron and Ames (1983)

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

Dichloro(methyl)silane

EC Number:

200-877-1

EC Name:

Dichloro(methyl)silane

Cas Number:

75-54-7

Molecular formula:

CH4Cl2Si

IUPAC Name:

dichloro(methyl)silane

Method

Species / strain

Species / strain / cell type:

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

Metabolic activation:

with and without

Metabolic activation system:

Rat liver; Induced by Aroclor 1254

Test concentrations with justification for top dose:

1st test: 20, 100, 500, 2500, 12500 µg/plate
2nd test: 75, 150, 300, 600, 1200, and 2400 µg/plate

Vehicle / solvent:

The solvent (negative control) for the test substance was ethylene glycoldimethylether anhydrous (EGDME), and for the positive controls, dimethylsulfoxide (DMSO). 

Controls

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Remarks:

See table 1

Details on test system and experimental conditions:

METHOD OF APPLICATION: in medium; in agar (plate incorporation); preincubation; in suspension; as impregnation on paper disk


DURATION

- Exposure duration: 48 h
- Expression time (cells in growth medium): 48 h


NUMBER OF REPLICATIONS: 4 plates per strain and dose


DETERMINATION OF CYTOTOXICITY
- Method: other: reduction in background lawn; reduction in mutant count relative to control; total bacterial count

Evaluation criteria:

Responses (number of revertants) to the test substance were compared to concurrent negative and positive controls, as well as to historical data.

Results and discussion

Test results

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:

100 μg/plate strain TA 98

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

COMPARISON WITH HISTORICAL CONTROL DATA: The positive and solvent control results were acceptable in comparison with historical contro data.

ADDITIONAL INFORMATION ON CYTOTOXICITY: At all tested doses, the test substance had a strong strain-specific bacteriotoxic effect, so that this range could only be used to a limited extent up to 2500 µg/plate for evaluation purposes.  

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

Any other information on results incl. tables

Table 3a Experiment 1- Mutagenicity Assay. Number of revertants per plate (mean of 3 plates). Strain   TA 1535 TA 100 Conc. (μg/plate) - MA + MA Cytotoxic (yes/no) -MA + MA Cytotoxic (yes/no) 0* 15 11 no 84 111 no 20 17 13 no 82 113 no 100 23 12 no 77 128 no 500 20 11 no 84 107 no 2500 17 15 no 67 145 no 12500 0 -- yes 0 --- yes Positive control 766 162 - 248 366 - * Solvent control EDGMA Table 3b Experiment 1- Mutagenicity Assay. Number of revertants per plate (mean of 3 plates). Strain   TA 1537 TA 98 Conc. () - MA + MA Cytotoxic (yes/no) -MA + MA Cytotoxic (yes/no) 0* 9 6 no 18 146 no 20 10 8 no 19 91 no 100 11 7 no 16 51 yes** 500 10 6 no 20 41 yes** 2500 7 3 no 7 64 yes** 12500 0 - yes 0 -- yes** Positive control 78 34 - 78 400 - * Solvent control EDGMA ** Reduction in mean number of revertants to <50% solvent control (reviewer's judgement) Table 4a Experiment 2- Mutagenicity Assay. Number of revertants per plate (mean of 3 plates). Strain   TA 1535 TA100 Conc. (μg/plate) - MA + MA Cytotoxic (yes/no) -MA + MA Cytotoxic (yes/no) 0* 20 24 149 206 75 21 19 no 136 199 no 150 18 23 no 148 195 no 300 19 18 no 150 170 no 600 22 18 no 140 185 no 1200 20 18 no 133 151 no 2400 18 12 no 88 87 yes** Positive control 799 386 - 451 1014 - * Solvent control EDGMA ** Reduction in mean number of revertants to <50% solvent control (reviewer's judgement) Table 4b Experiment 2- Mutagenicity Assay. Number of revertants per plate (mean of 3 plates). Strain   TA 1537 TA98 Conc. (μg/plate) - MA + MA Cytotoxic (yes/no) -MA + MA Cytotoxic (yes/no) 0* 11 11 23 35 75 10 15 no 25 31 no 150 9 11 no 22 25 no 300 9 13 no 24 33 no 600 10 9 no 16 36 no 1200 8 10 no 21 23 no 2400 6 6 no 14 24 no Positive control 96 83 - 122 627 - * Solvent control EDGMA

 

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information):
negative with metabolic activation
negative without metabolic activation

The test substance, dichloromethylsilane (CAS No. 75-54-7), did not demonstrate genetic activity in any of the tests conducted in this evaluation, both with and without metabolic activation. The results indicate that the test substance was not considered mutagenic under these test conditions.