Registration Dossier

Diss Factsheets

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
Study period:
15 April to 3 July 2019
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2019
Report date:
2019

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Version / remarks:
(1997)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Remarks:
Freie und Hansestadt Hamburg, Behörde für Gesundheit und Verbraucherschutz, 20539 Hamburg, Germany
Type of assay:
bacterial reverse mutation assay

Test material

Constituent 1
Chemical structure
Reference substance name:
(chloromethyl)diethoxymethylsilane
EC Number:
218-657-9
EC Name:
(chloromethyl)diethoxymethylsilane
Cas Number:
2212-10-4
Molecular formula:
C6H15ClO2Si
IUPAC Name:
(2-chloro-1,1-diethoxyethyl)silane
Test material form:
liquid
Details on test material:
Purity approx. 99% (GC)

Method

Target gene:
his operon
Species / strain
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and 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 phenobarbitale and ß-Naphthoflavone
Test concentrations with justification for top dose:

pre-experiment: 0.316, 1.0, 3.16, 10.0, 31.6, 100, 316, 1000, 3160, 5000 µg/plate (with and without metabolic avctivation)
experiments: 10.0, 31.6, 100, 316, 1000, 3160 µg/plate (without metabolic avctivation)
experiments: 31.6, 100, 316, 1000, 3160, 5000 µg/plate (with metabolic activation)
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: Dimethylsulphoxide (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:
not specified
Positive controls:
yes
Positive control substance:
mitomycin C
other: sodium azide (TA100, TA1535 10µg/plate, -S9); 2-nitrofluorene (TA98 10µg/plate, -S9); 9-aminoacidine (TA1537 100µg/plate; -S9); mitomycin C ; 2-aminoanthracene (2-AA, TA100, TA1535 2µg/plate, +S9); benzo[a]pyrene (TA98, TA102, TA1537 10µg/plate, +S9)
Details on test system and experimental conditions:
METHOD OF APPLICATION: The first experiment was carried out as the standard plate incorporation method whereas the second was carried out as the preincubation method.

DURATION
- Exposure duration: 48 hours

NUMBER OF REPLICATIONS: triplicates each in two independent experiments

DETERMINATION OF CYTOTOXICITY
- Method: cloning efficiency & relative total growth

Evaluation criteria:
A test item is considered to show a positive response if
- the number of revertants is significantly increased (p ≤ 0.05, U-test according to MANN and WHITNEY) compared to the solvent control to at least 2-fold of the solvent control for TA98, TA100, TA1535 and TA1537 and 1.5-fold of the solvent control for TA102 in both independent experiments.
- a concentration-related increase over the range tested in the number of the revertants per plate is observed. The Spearman's rank correlation coefficient may be applied.
Positive results from the bacterial reverse mutation test indicate that a substance induces point mutations by base substitutions or frameshifts in the genome of Salmonella typhimurium.
A test substance for which the results do not meet the above criteria is considered non-mutagenic in the tested species.

Results and discussion

Test resultsopen allclose all
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:
at the top concentration of 3160 μg test item/plate in the plate incorporation test and in the preincubation test, without S9, in all test strains and in the preincubation test with S9 at the top concentration of 5000 μg/plate in test strain TA1535
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 102
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
at the top concentration of 3160 μg (Chloromethyl)-diethoxymethylsilane/plate in the plate incorporation test and in the preincubation test, each carried out without metabolic activation
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Additional information on results:
RANGE-FINDING/SCREENING STUDIES:
(Chloromethyl)diethoxymethylsilane was examined in two preliminary cytotoxicity tests (plate incorporation test without and with metabolic activation) in the Salmonella typhimurium test strain TA100. Ten concentrations ranging from 0.316 to 5000 μg/plate were tested.
Pronounced cytotoxicity (scarce background lawn and reduction of the number of revertants by more than 50%) was noted at concentrations of 3160 μg/plate onwards in the test without metabolic activation.
Hence, 3160 μg (Chloromethyl)diethoxymethylsilane/plate were chosen as top concentration for the main study in the experiments without metabolic activation and 5000 μg/plate in the experiments with metabolic activation.

COMPARISON WITH HISTORICAL CONTROL DATA:
the resulted are in range with the historical control data

Applicant's summary and conclusion

Conclusions:
In conclusion, under the present test conditions, (Chloromethyl)diethoxymethylsilane tested up to the cytotoxic concentration of 3160 µg/plate (without activation) or the top concentration of 5000 µg/plate (with activation) caused no mutagenic effect in the Salmonella typhimurium strains TA 98; TA1 00, TA 1535, TA 1537 and TA 102, neither in the plate incorporation nor in the preincubation test, each carried out without and with metabolic activation.

Categories Display