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Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

In a reliable in vitro genotoxicity study (Ames test) the substance was tested for mutagenicity in Salmonella typhimurium strains TA1535, TA1537, TA98 and TA100, and in Escherichia coli strain WP2 uvrA. Concentrations of up to 5000 μg/plate were tested. No evidence of mutagenic activity was seen at any concentration of the substance both in the presence and absence of a metabolic activation system. It was concluded that the substance showed no evidence of mutagenic activity in these bacterial systems under the test conditions employed.

Link to relevant study records
Reference
Endpoint:
in vitro gene mutation study in bacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
15 November 2017 - 04 December 2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Version / remarks:
July 21, 1997
Deviations:
no
GLP compliance:
yes
Type of assay:
bacterial reverse mutation assay
Specific details on test material used for the study:
Batch: 1013Q17761
Purity: 100%
Physical State / Appearance: Solid white powder
Expiry Date: 25 June 2018
Storage Conditions: At room temperature
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2
Details on mammalian cell type (if applicable):
The Salmonella typhimurium histidine (his) and the Escherichia coli tryptophan (trp) reversion system measures his- → his+ and trp- → trp+ reversions, respectively. The Salmonella typhimurium and Escherichia coli strains are constructed to differentiate between base pair (TA 1535, TA 100, and WP2 uvrA) and frameshift (TA 1537, TA 98) mutations.
Additional strain / cell type characteristics:
not specified
Metabolic activation:
with and without
Metabolic activation system:
Phenobarbital/β-naphthoflavone induced rat liver S9 were used as the metabolic activation system.
Test concentrations with justification for top dose:
Pre-Experiment/Experiment I: 3; 10; 33; 100; 333; 1000; 2500; and 5000 μg/plate
experiment II: 10; 33; 100; 333; 1000; 2500; and 5000 μg/plate
Vehicle / solvent:
Dimethyl Sulphoxide
Untreated negative controls:
yes
Remarks:
Untreated
Negative solvent / vehicle controls:
yes
Remarks:
DMSO
True negative controls:
no
Positive controls:
yes
Positive control substance:
sodium azide
methylmethanesulfonate
other: 4-nitro-o-phenylene-diamine; 2-aminoanthracene
Rationale for test conditions:
As per OCED Test Guideline
Evaluation criteria:
A substance is considered as a mutagen if a biologically relevant increase in the number of revertants exceeding the threshold of twice (strains TA 98, TA 100, and WP2 uvrA) or thrice (strains TA 1535 and TA 1537) the colony count of the corresponding solvent control is observed.
A dose dependent increase is considered biologically relevant if the threshold is exceeded at more than one concentration.
An increase exceeding the threshold at only one concentration is judged as biologically relevant if reproduced in an independent second experiment.
A dose dependent increase in the number of revertant colonies below the threshold is regarded as an indication of a mutagenic potential if reproduced in an independent second experiment. However, whenever the colony counts remain within the historical range of negative and solvent controls such an increase is not considered biologically relevant.
Statistics:
According to the OECD guideline 471, a statistical analysis of the data is not mandatory.
Key result
Species / strain:
S. typhimurium TA 1535
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity, but tested up to precipitating concentrations
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Key result
Species / strain:
S. typhimurium TA 1537
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity, but tested up to precipitating concentrations
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Key result
Species / strain:
S. typhimurium TA 98
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity, but tested up to precipitating concentrations
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Key result
Species / strain:
S. typhimurium TA 100
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity, but tested up to precipitating concentrations
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Key result
Species / strain:
E. coli WP2 uvr A
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity, but tested up to precipitating concentrations
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Additional information on results:
Precipitation of the substance in the overlay agar on the incubated agar plates was observed from 1000 to 5000 μg/plate. The undissolved particles had no influence on the data recording.
The plates incubated with the substance showed reduced background growth in experiment I in all strains with and without metabolic activation from 2500 to 5000 μg/plate. In experiment II normal background growth was observed in all strains used with and without S9 mix.
No toxic effects, evident as a reduction in the number of revertants (below the indication factor of 0.5), occurred in the test groups with and without metabolic activation.
Conclusions:
The substance showed no evidence of mutagenic activity in these bacterial systems under the test conditions employed.
Executive summary:

In the in vitro genotoxicity study (Ames test) the substance was tested for mutagenicity in Salmonella typhimurium strains TA1535, TA1537, TA98 and TA100, and in Escherichia coli strain WP2 uvrA. Concentrations of up to 5000 μg/plate were tested. No evidence of mutagenic activity was seen at any concentration of the substance both in the presence and absence of a metabolic activation system. It was concluded that the substance showed no evidence of mutagenic activity in these bacterial systems under the test conditions employed.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (negative)

Genetic toxicity in vivo

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

Justification for classification or non-classification

Based on the findings of a reliable in vitro genotoxicity study (Ames test) conducted on the substance, classification of the substance is not justified.