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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
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Justification for type of information:
Data is from peer reviewed publication

Data source

Reference
Reference Type:
publication
Title:
Mutagenicity of N,N’-dimethylurea and methylamine hydrochloride in the Ames Salmonella/microsome test: absence of mutagenic response
Author:
G.P. Meshram, R. Padma Maiini and Kola M. Rao
Year:
1992
Bibliographic source:
Mutation Research. 279 (l992) 275-280

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
other: as per mentioned below
Principles of method if other than guideline:
Gene mutation toxicity study was performed to determine the mutagenic nature of Methylamine hydrochloride (MAH)
GLP compliance:
no
Type of assay:
bacterial gene mutation assay

Test material

Constituent 1
Chemical structure
Reference substance name:
Methylammonium chloride
EC Number:
209-795-0
EC Name:
Methylammonium chloride
Cas Number:
593-51-1
Molecular formula:
CH5N.ClH
IUPAC Name:
methanamine
Constituent 2
Reference substance name:
Methylamine hydrochloride
IUPAC Name:
Methylamine hydrochloride
Details on test material:
Details on test material
- Name of test material (as cited in study report): MAH (Methylamine hydrochloride)
- Molecular formula (if other than submission substance): CH5N.Cl H
- Molecular weight (if other than submission substance): 67.5184 g/mol
- Substance type: Organic
- Physical state:
Purity-98%
- Impurities (identity and concentrations): 2%
Specific details on test material used for the study:
- Name of test material: Methylamine hydrochloride (MAH)
- IUPAC name: Methanaminium chloride
- Molecular formula: CH5NCl H
- Molecular weight: 67.5184 g/mol
- Substance type: Organic
- Physical state: No data
- Purity-98%
- Impurities (identity and concentrations): 2%

Method

Target gene:
Histidine
Species / strain
Species / strain / cell type:
S. typhimurium, other: TA98, TA100 and TA104
Details on mammalian cell type (if applicable):
Not applicable
Additional strain / cell type characteristics:
other: Histidine-deficient (His-) mutants
Cytokinesis block (if used):
No data
Metabolic activation:
with and without
Metabolic activation system:
S9 fraction was prepared from Aroclor 125-l-pretreated male Wistar rats
Test concentrations with justification for top dose:
0, 0.08, 0.8, 1.6, 16.0, 32.0, 64.0 mg/plate
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: DMSO
- Justification for choice of solvent/vehicle: The chemical was soluble in DMSO
Controls
Untreated negative controls:
yes
Remarks:
DMSO
Negative solvent / vehicle controls:
yes
Remarks:
DMSO
True negative controls:
not specified
Positive controls:
yes
Positive control substance:
4-nitroquinoline-N-oxide
other: 2-aminofiuorene (All strains; With S9); 2,4,7-Trinitro-9.fluorenone (TA98; Without S9); Methylglyoxal (TA104; WIth S9)
Details on test system and experimental conditions:
METHOD OF APPLICATION: Liquid preicubation assay

DURATION
- Preincubation period: 12 hour
- Exposure duration: 30 min
- Expression time (cells in growth medium): - Selection time (if incubation with a selection agent):
- Fixation time (start of exposure up to fixation or harvest of cells): 48 hour
METHOD OF APPLICATION: Liquid preincubation assay
- Cell density at seeding (if applicable): No data

DURATION
- Preincubation period: 30 mins
- Exposure duration: 48 hrs
- Expression time (cells in growth medium): 48 hrs
- Selection time (if incubation with a selection agent): No data
- Fixation time (start of exposure up to fixation or harvest of cells): No data

SELECTION AGENT (mutation assays): No data

SPINDLE INHIBITOR (cytogenetic assays): No data

STAIN (for cytogenetic assays): No data

NUMBER OF REPLICATIONS: Duplicate

METHODS OF SLIDE PREPARATION AND STAINING TECHNIQUE USED: No data

NUMBER OF CELLS EVALUATED: No data

NUMBER OF METAPHASE SPREADS ANALYSED PER DOSE (if in vitro cytogenicity study in mammalian cells): No data

CRITERIA FOR MICRONUCLEUS IDENTIFICATION: No data

DETERMINATION OF CYTOTOXICITY
- Method: mitotic index; cloning efficiency; relative total growth; other: Yes, number of surviving cells were counted
- Any supplementary information relevant to cytotoxicity: No data

OTHER EXAMINATIONS:
- Determination of polyploidy: No data
- Determination of endoreplication: No data
- Methods, such as kinetochore antibody binding, to characterize whether micronuclei contain whole or fragmented chromosomes (if applicable): No data

- OTHER: No data
Rationale for test conditions:
No data
Evaluation criteria:
Each plate was examined under the microscope for the presence of background lawn (His-, auxotrophs). The mutagenic response was considered to be positive if the mean number of His’ revertant colonies obtained was double the negative (solvent) control at any dose, either in the presence or in the absence of S9 mix.
Statistics:
Mean ± SD

Results and discussion

Test results
Species / strain:
S. typhimurium, other: TA98, TA100 and TA104
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
At 64 mg/plate
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Remarks:
Positive mutagens used resulted in a strongly positive mutagenic response by inducing a multiple-fold increase in the number of His’ revertant colonies over the negative control.
Additional information on results:
No data

Applicant's summary and conclusion

Conclusions:
Methylamine hydrochloride (MAH) failed to induce gene mutation in Salmonella typhimurium strain TA98, TA100 and TA104 both in the presence and absence of S9 metabolic activation system and hence is not likely to classify as a gene mutant in vitro.
Executive summary:

Gene mutation toxicity study was performed to determine the mutagenic nature of Methylamine hydrochloride (MAH; IUPAC name: Methanaminium chloride). Liquid preicubation assay was performed using Salmonella typhimurium strain TA98, TA100 and TA104 in the presence and absence of 5%, 15% and 30% S9 metabolic activation system. The test chemical dissolved in DMSO was used at dose levels of 0, 0.08, 0.8, 1.6, 16.0, 32.0 or 64.0 mg/plate. Duplicate plates were set at each dose level. DMSO was used as negative control and concurrent positive control chemicals were also included in the study. The mutagenic response was considered to be positive if the mean number of His- revertant colonies obtained was double the negative (solvent) control at any dose, either in the presence or in the absence of S9 mix. MAH at the highest dose of 64 mg/plate was toxic, reducing the surviving cells in comparison to DMSO. Positive mutagens used in the present study resulted in a strongly positive mutagenic response by inducing a multiple-fold increase in the number of His- revertant colonies over the negative control. Methylamine hydrochloride (MAH) failed to induce gene mutation in Salmonella typhimurium strain TA98, TA100 and TA104 both in the presence and absence of S9 metabolic activation system and hence is not likely to classify as a gene mutant in vitro.